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Home My WebLink AboutLUA 09-099 & LUA-09-100_MiscCC:©JmWest = E@st: ~®[n)lt@m1/·~@~~M@~te King County, WA ' ¥ cei «= lhl llil a cca1 ~ JI llil i'f <Ol B" IJ'iTi) ai u: a (0) llil ~ cei IP (Q) irt .. ' Prepared for · , . . 1, Cam West Real Estate Development,·Inc. 1"' .·. J. ·".®.-.::~ 0 ti@':;o'i;' 'i .I' •• , '~ ., 1 .· ,,; I 2 i~i:,• .... · Al.JG .,,.,,' ~:· Triad Job No. 01-047 tc(tDD.~. . :., Cam West -East Triad Job No. 01-047 '' ,, ,,1·,1/' 1 •; • ',t •,I'," 11 ,•\1),,.'•'-,1'\1}, 11, 11'''( \1,,,,1 ,,' t) :f'. •:11 \,,')"'' \•\,' ,'/tfi:1 11 i:':.'1,;::. ~. l••!),,l,i:;1,' .'-r /, '1' ,;.' ,1 ,,., i; , ··' ;,-. 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' ,1, ,, •/' ;"1',.'1/1' ,'{ •,) \ ""I,, 1;/',n•1111,/I' ,r.,..,/,,1'.v• 'J'11•/1l,/."/f1 ''"1;,i1a•• if1'I ,,. ilf'11 {Jiii/~l/,11,J' ,,1,11•;,,.• ,//11,''1.',' ,Ii!'/ Renton/Rosemorite . ~ .: ;JR6ghni 1eaf. ;Ii~foii~~ti,6B\:,R~t::6~~ :·~ ~· ;·i~1/;,;:;i:: 1 ~?}:Jf ' ',• ·,;, i, •• ~ ',1•,,',t' , •. ,~.,/ .,,i;~··"1~·.i1.'11/W,11,1'f,1r.~; .. ;,1,,'a,',,1·,,; .. •1,Jl,.~.·'1 ,,1:6 1' 111,,,wl,11··:.'11,1,''/,',,,J I 'I/JI : ' ~ \ , • • ',, ", c ' , 1 11 •; ''!1 ,, ''('·t.: , '',ti ' " ';,~···\ 'f~f\ :, I'.', ':.'.l,.::~·i<:!\11 ,;Iii~,,: ',,,~ .,;,'1,:· 1i1l1,1,, :,IL·~~t~!·;,/;;t, :1, , 1-1 1~' ,i' ~\'.:,11,f~,::;~ 1.1/U,W , 'i' i' .~'I/ '. l~:,1ii.}~ .. ·:,(t'l1Ji , , "1, ' , • . . '' " .. •" ,, ' /, 'I \,Ii'·' I t 1 '. '"',' 1 ' ,/, 1,, /I• '/, ,, , ' /J '/ '1 ,,; ,,•11•,1 /,,! ' '.''! '')'~" ),'· .. ~ • ,,,, .'.:;1:i;;!;\}}:. :: ·ir?.:;\;/:i::}!?f i~t?1/f 1{;;;,f ;ir}J(';:t})!.;}.,tf ;;;;;;~;;;?:::t'.Ji:::i\~;Jf ff?: ' ) EAST RENTON/ROSEMONTE TECHNICAL INFORMATION REPORT City of Renton, Washington Prepared For: Cam West Real Estate Development, Inc. 9720 NE 120th Place, Suite 100 Kirkland, WA 98034 Issued August 14, 2007 Revised February 20, · 2008 Revised April 10, 2008 Revised August 7, 2008 Prepared By: Tyson Wentz, EIT Reviewed By: Sheri Murata, PE Job #01-047 (c:i:) [!) ~ = 1l!!!l ~ ll!!!J r@s • § UJ = u.f ""' "' q, 0 i::!) d = < ~ ) East Renton/Rosemonte -Technical Information Report TABLE OF CONTENTS I PROJECT OVERVIEW ......................................................................................................................... 1-1 2 CONDITIONS AND REQUIREMENTS SUMMARY ........................................................................ 2-I 2.1 HEARING CONDITIONS ............................................................................................ 2-1 2.2 CORE REQUIREMENTS ........................................................................................... 2-23 3 OFFSITE ANALYSIS ............................................................................................................................. 3-1 4 FLOW CONTROL AND WATER QUALITY DESIGN ..................................................................... 4-1 4.1 DETENTION FACILITY ............................................................................................. 4-2 5 CONVEYANCE SYSTEM ANALYSIS & DESIGN ............................................................................ 5-8 5.1 CONVEYANCE CONCEPT AND METHODOLOGY ........................................................ 5-8 5.2 FLOW USING THE RATIONAL METHOD & KCRTS-15 MINUTE TIME STEPS ............. 5-9 FREEBOARD TABLES ......................................................................................................... 5-12 6 SPECIAL REPORTS AND STUDIES ................................................................................................... 6-I 6.1 GEOTECHNICAL REPORTS ....................................................................................... 6-1 6.2 WETLAND DETERMINATION REPORT ...................................................................... 6-1 6.3 WETLAND RECHARGE ............................................................................................. 6-1 7 OTHER PERMITS .................................................................................................................................. 7-1 8 TESC ANALYSIS, DESIGN AND CONSTRUCTION STORMWATER POLUTION PREVENTION PLAN ...................................................................................................................................... 8-1 8.1 SEDIMENT BASINS .................................................................................................. 8-1 9 BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT ....... 9-1 9 .1 BOND QUANTITIES .................................................................................................. 9-1 9.2 FACILITY SUMMARIES ............................................................................................. 9-1 9.3 DECLARATION OF COVENANT ................................................................................. 9-1 10 OPERATIONS AND MAINTENANCE .............................................................................................. 10-I Job #01-047 August 7, 2008 Page i SECTION I TJR WORKSHEET SECTION2 East Renton/Rosemonte -Technical Information Report LIST OF SUPPLEMENTAL INFORMATION HEARING CONDITIONS, EAST RENTON, DA TED APRJL 5, 2007 HEARING CONDITIONS, ROSEMONTE, DATED APRJL 10, 2007 KC ROAD V ARJANCE AND DRAINAGE ADJUSTMENT SECTI0N3 LEVEL I DOWNSTREAM ANALYSIS REPORT SECTI0N4 EXISTING CONDITIONS EXHIBIT DEVELOPED CONDITIONS EXHIBIT FIGURE 3.2.2A RAINFALL REGIONS AND REGIONAL SCALE FACTORS TABLE 3.2.2B 2005 KCSWM SCS SOIL TYPES KING COUNTY SCS MAP KING COUNTY SCS LEGEND KCRTS PRJNTED DOCUMENTATION FIGURE 6.4.1.A PRECIPITATION FOR MEAN ANNUAL STORM POND VOLUME SPREADSHEET SECTIONS FIGURE 3.2.1.D I 00-YEAR 24-HOUR ISO PLUVIALS CATCH BASIN TRJBUT ARY AREA EXHIBIT KCBW DOCUMENTATION SECTION6 GEOTECHNICAL ENGINEERING REPORT FOR Rosemonte-East Renton Property, by ASSOCIATED EARTH SCIENCE, INC. dated November 12, 2007 WETLAND DETERMINATION FOR EAST RENTON by C. GARY SCHULZ dated September J 2. 2002 EXISTING WETLAND TRJBUTARY AREA EXHIBIT DEVELOPED WETLAND TRJBUTARY AREA EXHBIT SECTIONS TESC PLAN ANO EARLY GRADING TRJBUTARY AREA EXHIBIT SECTI0N9 STORMWATER FACILITY SUMMARY SHEET REDUCED SIZE ROAD AND STORM PONO SHEETS 18-20 Job#01-047 August 7, 2008 Page ii East Renton/Rosemonte -Technical Information Report 1 PROJECT OVERVIEW The project proposes to create 91 single-family lots in two phases including open space, sensitive areas, recreation and a detention tract on a 26.54 acre property. The site is bounded east by 148th Avenue Southeast and north by Southeast 118th Street (if extend to the west). The site is bounded by parcel 1023059017 to the west and parcel 1023059368 to the south. The project is generally located west of the intersection of 148th Avenue Southeast and Southeast 120th Street; Section IO, Township 23 north, Range 5 east, W.M., King County, Washington. The Vicinity Map below shows the general location of the site. This Technical Information Report follows the 1998 King County Surface Water Design Manual (KCSWDM). , !I ii )-•' ,1,-~ '\ , r: . I J--. , ---------------1T ______ l_\ ---------,J' ------; ---- 0 I _4Q.• L --, J_ i /..-,.1. . Ii ! 1------::-1--r -J , I ---"-1 '<.-·._ \ ----1 ',, I ,, ..., MAY V'-'1/1_[)"" -1, '· I II \ -/ -~OUNT'r /J,1HI( __ f\~\ .. ,-~ ',, I I Job #01-047 August?,2008 I ~ -L-1 -, ----. Jk, ' ! -1C---I '-'.,:ts:..:r., ·----- 1 I'S: _ __J 1-·,){,,-:,: . I 1 -,,.. ~. : r·--·1"'' \ __ >'_<_, \, -.:.:: SE ii6ti, ·~1 Vi<eill'ility Mai!P) NOTTO SCALE Page 1-1 East Renton/Rosemonte -Technical Information Report Currently the site consists of two existing single-family homes, a shop, a small covered storage building, and a gravel driveway (all to be removed). A wetland area exists along the western portion of the site that will not be disturbed and set aside in Tract F and G. The existing site has one drainage basin that drain into Honey Dew Creek which, according to the December 1990 King County Sensitive Areas Map Folio, is an unclassified stream in the May Creek Sub-Basin. Honey Dew Creek combines with May Creek greater than two miles downstream (north) of the site. May Creek is in the Cedar River Drainage basin and ultimately discharges into Lake Washington. Refer to the Level I Downstream Analysis in Section 3, which was submitted on November I 0, 2004, for a full description of the existing site and drainage patterns. Storrnwater management for the proposed development will require the construction of a detention and water quality pond. Wetland recharge will also be incorporated onsite. Job #01-047 August 7, 2008 Page 1-2 King County Department of Development and Environmental Services TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Project Owner: CamWest Real Estate Development. Inc. Address: 9720 NE 12d1' Place Suite 100 Kirkland. WA 98034 Phone: (425/ 825-1955 Project Engineer: Sheri Murata. P. E. Company: Triad Associates Address/Phone: 425 821-8448 X Subdivison D Short Subdivision D Grading D Commercial D Other Community: Renton Drainage Basin: Project Name: East Renton!Rosemonte Location: Township: 23 N Range: 5 E Section: 10 X DFWHPA D Shoreline Management D COE404 X Rockery D DOE Dam Safety D Structural Vaults D FEMA Floodplain D Other D COE Wetlands Lower Cedar River River Sub-basin of Cedar River Sub-basin D D D D D D River Stream Critical Stream Reach Depressions/Swales Lake Steep Slopes ,&c~I". 1,m~-, .. ,.,.,.~,::."iJ!i!l.;· " 1tS · · :if . ~'ttt1Q~~f.\&i:1 , .... ;1w ,: ·H r:f\ 1!)1~~.!l~~Jf~~~~~Mi\~.; Soil Type AqB AgC Slopes 0-6% 6-15% D Floodplain X Wetlands D Seeps/Springs D High Groundwater Table D Groundwater Recharge D Other Erosion Potential Slight Moderate Erosive Velcoties Slow Slow to Medium I REFERENCE D Ch. 3-Downstream Analysis D D D D D D Additional Sheets Attached MINIMUM ESC REQUIREMENTS DURING CONSTRUCTION X Sedimentation Facilities X Stabilized Construction Entrance X Perimeter Runoff Control X Clearing and Graing Restrictions X Cover Practices X Construction Sequence X Other I MINIMUM ESC REQUIREMENTS AFTER CONSTRUCTION X Stabilize Exposed Surface X Remove and Restore Temporary ESC Facilities X Clean and Remove All Silt and Debris X Ensure Operation of Permanent Facilities X Flag Limits of SAO and open space preservation areas D Other D Grass Lined D Tank D Infiltration Method of Analysis Channel D D KCRTS Level 1 Vault Depression X Pipe System D Compensation/Mitigation Energy X Flow Dispersal of Eliminated Site D Open Channel Dissapator D Storage Waiver D Dry Pond D Wetland D ' Regional X Wet Pond D Stream Detention Brief Description of System Operation: Level 1 KCRTS detention pond with basic water quality wetpond. Facility Related Site Limitations Reference Facility Limitation D Cast in Place Vault X Retaining Wall X Rockery> 4' High D Structural on Steep Slope D Other X Drainage Easement D Access Easement D Native Growth Protection Easement X Tract D Other I or a civil engineer under my supervision my supervision have visited the site. Actual site conditions as observed were incorporated into this worksheet and the attachments. To the best of my knowledge the information provided here is accurate. ) East Renton/Rosemonte -Technical Information Report 2 CONDITIONS ANID REQUIRIEMENTS SUMMARY 2.1 Hearing Conditions East Renton The proposed preliminary plat of East Renton, as revised and received on March 17, 2006, is approved, subject to the following conditions of final plat approval: I. Compliance with all platting provisions of Title 19A of the King County Code. Condition Noted. 2. All persons having an ownership interest in the subject property shall sign on the face of the final plat a dedication that includes the language set forth in King County Council Motion No. 5952. Condition Noted. 3. The plat shall comply with the base density and minimum density requirements of the R-4 zone classification. All lots shall meet the minimum dimensional requirements of the R-4 zone classification or shall be as shown on the face of the approved preliminary plat, whichever is larger, except that minor revisions to the plat which do not result in substantial changes may be approved at the discretion of the Department of Development and Environment Services. Condition Noted. Any/all plat boundary discrepancy(ies) shall be resolved to the satisfaction of DOES prior to the submittal of the final plat documents. As used in this condition, "discrepancy" is a boundary hiatus, an overlapping boundary or a physical appurtenance which indicates an encroachment, lines of possession or a conflict of title. · 4. The applicant must obtain final approval from the King County Health Department. Condition Noted. 5. All construction and upgrading of public and private roads shall be done in accordance with the King County Road Standards established and adopted by Ordinance No. 11187, as amended (1993 KCRS). (Also see conditions 8 and 24.) All roads have been designed per the 1993 KCRS. 6. The applicant must obtain the approval of the King County Fire Protection Engineer for the adequacy of the fire hydrant, water main, and fire flow standards of Chapter 17.08 of the King County Code. Plans have been submitted to the Fire Marshal. All future residences constructed within this subdivision are required to be sprinklered (NFPA !3D) unless the requirement is removed by the King County fire Marshal or his/her designee. The Fire Code requires all portions of the exterior walls of structures to be within 150 feet (as a person would walk via an approved route around the building) from a minimum 20-foot wide, unobstructed driving surface. To Job #01-047 August 7, 2008 Page 2-1 East Renton/Rosemonte -Technical Information Report qualify for removal of the sprinkler requirement, driving surfaces between curbs must be a minimum of 28 feet in width when parking is allowed on one side of the roadway, and at least 36 feet in width when parking is permitted on both sides. The road width requirement applies to both on-site access and roads accessing the subdivision. 7. Final plat approval shall require full compliance with the drainage provisions set forth in King County Code 9.04. Compliance may result in reducing the number and/or location of lots as shown on the preliminary approved plat. Preliminary review has identified the following conditions of approval, which represent portions of the drainage requirements. All other applicable requirements in KCC 9.04 and the Surface Water Design Manual (SWDM) must also be satisfied during engineering and final review. a. Drainage plans and analysis shall comply with the 1998 King County Surface Water Design Manual. DDES approval of the drainage and roadway plans is required prior to any construction. The drainage plans and analysis have been provided in compliance to the 1998 KCSWDM and applicable updates. b. Current standard plan notes and ESC notes, as established by DDES Engineering Review shall be shown on the engineering plans. The current standard plan notes and ESC notes have been provided on sheet 7. c. The following note shall be shown on the final recorded plat: "All building downspouts, footing drains, and drains from all impervious surfaces such as patios and driveways shall be connected to the permanent storm drain outlet as shown on the approved construction drawings # on file with DDES and/or the Department of Transportation. This plan shall be submitted with the application of any building permit. All connections of the drains must be constructed and approved prior to the final building inspection approval. For those lots that are designated for individual lot infiltration systems, the systems shall be constructed at the time of the building permit and shall comply with the plans on file." Condition Noted. d. Storm water· facilities shall be designed using the KCRTS level one flow control standard. Water quality facilities shall also be provided using the basic water quality protection menu. The size of the proposed drainage tracts may have to increase to accommodate the required detention volumes and water quality facilities. All runoff control facilities shall be located in a separate tract and dedicated to King County unless portions of the drainage tract are used for recreation space in accordance with KCC 21A.14.180. The stormwater facilities have been designed to a Level 1 flow control and basic water quality per the 1998 KCSWDM and are shown in dedicated tracts. Job #01-047 August 7, 2008 Page 2-2 East Renton/Rosemonte -Technical Information Report e. The applicant has received approval for two drainage adjustment applications regarding designs for the discharge of storm water and a shared facility detention pond. The adjustment decisions are contained within file numbers L02V0089 and L04VOJ03. During final review of the engineering plans, all applicable conditions of the adjustment approvals shall be satisfied including requirements for the shared facility located offsite within the plat of Rosemonte. Condition Noted. f. As stated in the drainage adjustment decision, the offsite drainage pond shall be designed using the Level I flow control standard. Basic water quality standards are also required for design of the facility. If a wet pond facility is provided for water quality, the design shall comply with the 3:1 flow length ratio as outlined on page 6-72 in the drainage manual. For evaluation of the onsite storm vault and the offsite detention pond, a soils report shall be prepared by a geotechnical engineer to evaluate the soils and groundwater conditions. See Section 6 of the TIR for applicable reports. g. For any proposed bypass of storm water from the flow control facility, the final drainage designs shall comply with applicable design requirements in the drainage manual as outlined on pages 1-36 and 3-52. Detention facilities meet design requirements at point of compliance. h. As required by Special Requirement No. 2 in the drainage manual, the I 00- year floodplain boundaries for the onsite wetlands shall be shown on the final engineering plans and recorded plat. Condition Noted. Access and Roads 8. The proposed subdivision shall comply with the 1993 King County Road Standards (KCRS) including the following requirements: a. During preliminary review the applicant submitted a road variance application (File No. L03V0049), regarding the crest vertical curve and substandard stopping sight distance along the plat frontage. In response to the variance application, the King County Road Engineer provided a decision letter dated October 20, 2004 which ap;roved the variance based upon specific design criteria for constructing 148 Ave SE. As noted in the variance decision, the crest curve on 148th Ave SE must be reconstructed to provide 455 feet of stopping sight distance based upon design criteria with a 2-foot target. The final road improvements and design plans for the project shall demonstrate compliance with all applicable conditions of approval as stated in the variance decision. The vertical re-alignment is shown on sheets 14 and 15. b. 148th Avenue SE shall be improved along the frontage as an urban collector arterial including all design criteria from the road variance decision. In accordance with KCRS 2.02, the curb location shall be designed at 22-feet from the road crown to provide full width travel lanes and a bike lane. The preliminary design plans for East Renton shows road grading extending Job #01-047 August7,2008 Page 2-3 East Renton/Rosemonte -Technical Information Report outside the right-of-way on the east side of 148 1h Ave SE. During final engineering review, the applicant shall acquire easements for any proposed construction on private property or provide an alternative design which is acceptable to King County for road construction within the existing right-of- way. Please see sheets 14 and 15 for 1481h Ave SE improvements. Easements are not required. c. The project entry road to 148th Ave SE shall be improved as an urban neighborhood collector. As shown on the preliminary plat, the required right- of-way width is 56 feet. The entry road has been designed to the urban neighborhood collector standards. d. The proposed roads within the subdivision shall be improved using urban design standards and in accordance with the street classifications shown on the preliminary plat map. See Road and Storm plans for plan and profile views as well as road sections. e. Tract D shall be improved as a private joint use driveway serving a maximum of two Jots. The Jots served shall have undivided ownership of the tract and be responsible for its maintenance. As specified in KCRS 3.0IC, improvements shall include an 18 foot paved surface and a minimum tract width of 20 feet. Drainage control shall include a curb or thickened edge on one side. Tract D has been designed to the private access standard. f. Street trees shall be included in the design of all road improvements and shall comply with Section 5.03 of the KCRS. Street trees have been depicted on the landscape plans. g. Street illumination shall be provided along the plat frontage and at intersections with arterials in accordance with KCRS 5.05. Illumination has been shown on sheet 23. h. The proposed road improvements shall address the requirements for road surfacing outlined in KCRS Chapter 4. As noted in section 4.0lF, full width pavement overlay is required where widening existing asphalt, unless otherwise approved by King County. A note has been provided on the plans. i. 148th Ave SE is classified as an arterial street which may require designs for bus zones and tum outs. As specified in KCRS 2.16, the designer shall contact Metro and the local school district to determine specific requirements. Metro and the school district have been contacted. j. Modifications to the above road conditions may be considered by King County pursuant to the variance procedures in KCRS 1.08. Condition Noted. 9. All utilities within proposed rights-of-way must be included within a franchise approved by the King County Council prior to final plat recording. Condition Noted. Job #01-047 August7,2008 Page 2-4 East Renton/Rosemonte -Technical Information Report 10. The site plans for East Renton show the northerly road stub for 145th Ave SE which may extend into the wetland buffer and associated setback within the Rosemont plat. During engineering review for East Renton, a revised road alignment and grading plan shall be provided which demonstrates that road construction within Rosemonte will comply with applicable sensitive area codes. The revised road design and grading plan may result in modification or loss of lots as shown on the preliminary plat. Alternatively, the applicant may seek approval to use buffer averaging as a means to revise the location of the buffer and BSLB to achieve code compliance within Rosemonte. Condition Noted. 11. There shall be no direct vehicular access to or from 148th Ave SE from those lots which abut it. A note to this effect shall appear on the engineering plans and the final plat. The note has been provided on the Road and Storm plans. 12. The applicant shall provide a safe walking access to Apollo Elementary School with urban improvements along the west side of 148 1h Ave NE to the existing crosswalk on the north side of SE I 17th St. This improvement includes urban frontage improvements along property frontage of the Plat of East Renton, urban improvements along frontage ofRosemonte and urban improvements north to the existing crosswalk on the north side of SE 11 ih ST. (It is noted that the adjoining plat of Rosemonte also will be subject to urban frontage requirements and urban improvements north to the existing crosswalk on the north side of SE I 17th ST.) Curb, gutter and sidewalk has been designed on the west side of 148 1h Ave NE. In the event it is not practical to. construct urban improvements on the west side of 148th Avenue Southeast extending to the existing crosswalk, a new crosswalk may be established south of Southeast I 17th Street and a safe walkway provided on the east side of 148th A venue Southeast from the new crosswalk to the north side of Southeast I 17th Street. This alternative may use a graded surface on the east side of 148th Ave SE to ensure that school-age pedestrians are provided an acceptable-width walkway surface behind the curbing. The walkway shall be designed to the satisfaction of the school district and DOES. A crosswalk has been shown on the south side of 1171h Street. Easements could not be obtained to provide otherwise. Mitigation/Impact Fees 13. The applicant or subsequent owner shall comply with King County Code 14.75, Mitigation Payment System (MPS), by paying the required MPS fee and administration fee as determined by the applicable fee ordinance. The applicant has the option to either: (I) pay the MPS fee at the final plat recording, or (2) pay the MPS fee at the time of building permit issuance. If the first option is chosen, the fee paid shall be the fee in effect at the time of plat application and a note shall be placed on the face of the plat that reads, "All fees required by King County Code 14.75, Mitigation Payment System (MPS), have been paid." If the second option is chosen, the fee paid shall be the amount in effect as of the date of building permit application. Condition Noted. Job #01-047 August7,2008 Page 2-5 East Renton/Rosemonte -Technical Information Report 14. Lots within this subdivision are subject to King County Code 21A.43, which imposes impact fees to fund school system improvements needed to serve new development. As a condition of final approval, fifty percent (50%) of the impact fees due for the plat shall be assessed and collected immediately prior to the recording, using the fee schedules in effect when the plat receives final approval. The balance of the assessed fee shall be allocated evenly to the dwelling units in the plat and shall be collected prior to building permit issuance. Condition Noted. Wetlands 15. Preliminary plat review has identified specific requirements which apply to this project as listed below. All other applicable requirements from K.C.C. 21A.24 shall also be addressed by the applicant. a. The Class 2 wetland shall have a minimum SO-foot buffer of undisturbed vegetation as measured from the wetland edge. Onsite wetlands have been provided with buffers. Tracts and building setbacks are shown on the engineering plans. b. Sensitive area tract(s) shall be used to delineate and protect sensitive areas and buffers in development proposals for subdivisions and shall be recorded on all documents of title of record for all affected lots. Condition Noted. c. Buffer width averaging may be allowed by King County if it will provide additional protection to the wetland/stream or enhance their functions, as long as the total area contained in the buffer on the development proposal site does not decrease. In no area shall the buffer be less than 65 percent of the required minimum distance. To ensure such functions are enhanced a mitigation plan will be required for the remaining on-site sensitive areas. An enhancement plan shall be submitted for review during engineering review. Buffer averaging has been shown on the plans as well as enhancement. Please see the Landscape plans for the enhancement plan. d. A 15-foot BSBL shall be established from the edge of buffer and/or the sensitive areas Tract(s) and shown on all affected lots. Onsite wetlands have been provided with buffers. Tracts and building setbacks are shown on the engineering plans. e. To ensure long term protection of the Sensitive Areas a split-railed fence ofno more than 4 feet in height shall be installed along the Sensitive Area Tract boundaries in the area of proposed lots. Sensitive Area signs shall be attached to the fence at no less than I 00 foot intervals. Sensitive Area signs have been shown on the landscape plans. f. If alterations of streams and/or wetlands are approved in conformance with K.C.C. 21A.24, then a detailed plan to mitigate for impacts from that alteration will be required to be reviewed and approved along with the plat Job #01-047 August 7, 2008 Page 2-6 East Renton/Rosemonte -Technical Information Report engineering plans. A perfonnance bond or other financial guarantee will be required at the time of plan approval to guarantee that the mitigation measures are installed according to the plan. Once the mitigation work is completed to a DDES Senior Ecologist's satisfaction, the performance bond may be replaced by a maintenance bond for the remainder of the five-year monitoring period to guarantee the success of the mitigation. The applicant shall be responsible for the installation, maintenance and monitoring of any approved mitigation. The mitigation plan must be installed prior to final inspection of the plat. Condition Noted. g. Prior to commencing construction activities on the site, the applicant shall temporarily mark sensitive areas tract(s) in a highly visible manner, and these areas must remain so marked until all development proposal activities in the vicinity of the sensitive areas are completed. Condition Noted. h. During engineering plan review the applicant shall provide a wetland hydrology analysis to demonstrate how the wetland hydrology will be maintained post-construction. See Section 6 of the TIR. i. Detention out-fall structures maybe pennitted within the wetland/stream buffers, however, structures shall be located in the outer edge of the buffer, if possible. All buffer impacts shall be mitigated. Condition Noted. 16. Development authorized by this approval may require other state and/or federal pennits or approvals. It is the applicant's responsibility to correspond with these agencies prior to beginning work on the site. Condition Noted. 17. During engineering review, the plan set shall be routed to the sensitive areas group to detennine if the above conditions have been met. Condition Noted. Geo technical 18. The applicant shall delineate all on-site erosion hazard areas on the final engineering plans ( erosion hazard areas are defined in KCC 21 A.06.415). The delineation of such areas shall be approved by a DOES geologist. The requirements found in KCC 21A.24.220 concerning erosion hazard areas shall be met, including seasonal restrictions on clearing and grading activities. Condition Noted. Sensitive Area 19. The following note shall be shown on the final engineering plan and recorded plat: RESTRICTIONS FOR SENSITIVE AREA TRACTS AND SENSITIVE AREAS AND BUFFERS Dedication of a sensitive area tract/sensitive area and buffer conveys to the public a beneficial interest in the land within the tract/sensitive area and buffer. This interest Job #01-047 August 7, 2008 Page 2-7 ) ) Other 20. East Renton/Rosemonte -Technical Information Report includes the preservation of native vegetation for all purposes that benefit the public health, safety and welfare, including control of surface water and erosion, maintenance of slope stability, and protection of plant and animal habitat. The sensitive area tract/sensitive area and buffer imposes upon all present and future owners and occupiers of the land subject to the tract/sensitive area and buffer the obligation, enforceable on behalf of the public by King County, to leave undisturbed all trees and other vegetation within the tract/sensitive area and buffer. The vegetation within the tract/sensitive area and buffer may not be cut, pruned, covered by fill, removed or damaged without approval in writing from the King County Department of Development and Environmental Services or its successor agency, unless otherwise provided by law. The common boundary between the tract/sensitive area and buffer and the area of development activity must be marked or otherwise flagged to the satisfaction of King County prior to any clearing, grading, building construction or other development activity on a lot subject to the sensitive area tract/sensitive area and buffer. The required marking or flagging shall remain in place until all development proposal activities in the vicinity of the sensitive area are completed. No building foundations are allowed beyond the required 15-foot building setback line, unless otherwise provided by law. Condition Noted. The plat design shall be revised to provide the minimum suitable recreation space consistent with the requirements ofK.C.C. 21A.14.180 and K.C.C. 21A. 14.190 (i.e., minimum area, as well as, sport court[s], children's play equipment, picnic table[s), benches, etc.), as shown on hearing exh. no. 26. Recreation plans, performance bond and homeowners' association will be provided. a. A detailed recreation space plan (i.e., location, area calculations, dimensions, landscape specs, equipment specs, etc.) shall be submitted for review and approval by DOES prior to or concurrent with the submittal of engineering plats. b. A performance bond for recreation space improvements shall be posted prior to recording of the plat. 21. Tract E shall be designated for recreational area, with an approved trail ( across wetland buffers) extending from the recreational Tract G and functioning as an extension ofrecreation from Tract G. Plans for the tract -designation and design, shall comply with codes and shall be to the satisfaction of ODES prior to engineering approval. Condition Noted. 22. A homeowners' association or other workable organization shall be established to the satisfaction of DOES which provides for the ownership and continued maintenance of the recreation, open space and/or sensitive area tract(s) which combines usage of recreation area within L03POOl8, the plat ofRosemonte, pursuant to hearing exh. no. Job #01-047 August 7, 2008 Page 2-8 ) ) ) 23. East Renton/Rosemonte -Technical Information Report 26. (See condition no. 25.) A homeowner's association or other workable organization will be established by the applicant. Street trees shall be provided as follows (per KCRS 5.03 and K.C.C. 21A.16.050): Street trees have been shown on the landscape plans as outlined below. a. Trees shall be planted at a rate of one tree for every 40 feet of frontage along all roads. Spacing may be modified to accommodate sight distance requirements for driveways and intersections. b. Trees shall be located within the street right-of-way and planted in accordance with Drawing No. 5-009 of the 1993 King County Road Standards, unless King County Department of Transportation determines that trees should not be located in the street right-of-way. c. If King County determines that the required street trees should not be located within the right-of-way, they shall be located no more than 20 feet from the street right-of-way line. d. The trees shall be owned and maintained by the abutting lot owners or the homeowners association or other workable organization unless the county has .. adopted a maintenance program. Ownership and maintenance shall be noted on the face of the final recorded plat. e. f. g. h. i. The species of trees shall be approved by DOES if located within the right-of- way, and shall not include poplar, cottonwood, soft maples, gum, any fruit- bearing trees, or any other tree or shrub whose roots are likely to obstruct sanitary or storm sewers, or that is not compatible with overhead utility lines. The applicant shall submit a street tree plan and bond quantity sheet for review and approval by ODES prior to engineering plan approval. The applicant shall contact Metro Service Plannin.!f at (206) 684-1622 to determine if 148th Ave SE is on a bus route. If 148 Ave SE is a bus route, the street tree plan shall also be reviewed by Metro. The street trees must be installed and inspected, or a performance bond posted prior to recording of the plat. If a performance bond is posted, the street trees must be installed and inspected within one year of recording of the plat. At the time of inspection, if the trees are found to be installed per the approved plan, a maintenance bond must be submitted or the performance bond replaced with a maintenance bond, and held for one year. After one year, the maintenance bond may be released after DOES has completed a second inspection and determined that the trees have been kept healthy and thriving. A landscape inspection fee shall also be submitted prior to plat recording. The inspection fee is subject to change based on the current county fees. Job #01-047 August 7, 2008 Page 2-9 ) East Renton/Rosemonte -Technical Information Report SEPA 24. The following have been established by SEPA as necessary requirements to mitigate the adverse environmental impacts of this development. The applicants shall demonstrate compliance with these items prior to final approval. (I.) To mitigate the significant adverse impact the plat of East Renton will have on the intersections of SR 9001148th Ave SE and SR 9001164th Ave SE, the applicant shall install, either individually or in conjunction with other development projects in this area, the following improvements at the SR 9001148th Ave intersection: o A traffic signal, and o Eastbound and westbound left turn lanes The design for the SR 900/148th Ave intersection improvements shall be approved by the Washington State Department of Transportation (and by King County to the extent such improvements are located in County right-of-way). In addition, at a minimum, the existing entering sight distance looking east for the north and south legs of the intersection (602 feet and 386 feet, respectively) shall not be reduced as part of the intersection improvements. Documentation shall be submitted to show this requirement is met. All construction work associated with the intersection improvements shall be completed between April J" and September 30 1h. This seasonal restriction shall be clearly shown on the final engineering plans. In lieu of the installation of the above-noted intersection improvements prior to final plat approval, the applicant may post a financial guarantee with WSDOT which assures the installation of these improvements within two years of the recording of East Renton. In this event, intersection improvement design must be approved by WSDOT prior to King County approval of the engineering plans for East Renton. If the above-noted intersection improvements have already been made by others prior to the recording of East Renton, or a financial guarantee has been posted by others which assures the installation of these improvements, then the applicant for East Renton shall pay a pro-rata share dollar amount to the developer who has made the improvements or "bonded" for the improvements, in an amount proportional to the impacts of East Renton. The pro-rata share dollar amount to be paid shall be set by WSDOT, and documentation shall be provided by the East Renton applicant to the King County Land Use Services Division to show this payment has been made, prior to final plat recording. The pro-rata dollar amount to be paid shall be based on the following: Job#01-047 August?,2008 o The final East Renton lot count o The trip distribution for East Renton o The total trips contributed to the intersection of SR 900.148th Ave by the plats of Aster Park (LOOP0024), Stone Ridge 9L99P3008), East Renton (L02P0005), Shamrock (L02POOJ4), Rosemonte (aka Ironwood- L03POOJ8), Martin (L05POOJ9) and any future land use applications Page2-10 East Renton/Rosemonte -Technical Information Report submitted to King County for which compliance with the King County Intersection Standards (KCC 14.80) is required at either the SR 900/l 48 1h Ave intersection, or the SR 9001164th Ave High Accident Location. In the event that either King County or WSDOT adopts a formal "latecomer's" system prior to final plat recording, that system may be followed in lieu of the approach described above, at the discretion of the applicant, as long as at a minimum there is a financial guarantee which assures the above-noted intersection improvements will be installed within two years of the date of recording of the plat of East Renton. [Comprehensive Plan Policy T-303 and King County Code 21A.28.060A] (2.) Documentation shall be provided to demonstrate to the satisfaction of WSDOT that stopping sight distance (360 feet) is available on the east leg of the SR 900/l 48th Ave intersection. The intersection shall be modified by the applicant, if necessary, so that this stopping sight distance requirement is met on the east leg. In addition, the applicant shall clear vegetation within the right-of-way along SR 900, east of 148th Ave., to maximize the entering sight distance for the north and south legs of the intersection. [Comprehensive Plan Policy T-303 and King County Comprehensive Policy T-303 and King County Code 21A.28.060A] This SEPA condition is under construction by others. 25. The recreation area may serve the adjacent plat of Rosemonte. If necessary, boundary line adjustments may be approved to establish a portion of the East Renton plat recreation area as a part of the Rosemonte Plat, or the two plats may be recorded as a single plat. Condition Noted. 26. Wetland buffer averaging or additional buffer are required to compensate for reduction of wetland buffers adjacent to 145th Avenue southeast, as proposed in the vicinity of the north property line, and to compensate for construction of the recreation tract trail through wetland buffer between Tracts E and G. Condition Noted. Rosemonte The proposed preliminary plat of Rosemonte as revised and revised and received on March 31, 2006 is approved, subject to the following conditions of final plat approval: I. Compliance with all platting provisions of Title 19 A of the King County Code. Actual final recording of the plat of Rosemonte/L03POOl 8 shall either occur subsequent to or concurrent with the recording of the Plat of East Renton/L02P0005. Condition Noted. Job #01-047 August 7, 2008 Page 2-11 East Renton/Rosemonte -Technical Information Report 2. All persons having an ownership interest in the subject property shall sign on the face of the final plat a dedication that includes the language set forth in King County Council Motion No. 5952. Condition Noted. 3. The plat shall comply with the base density and minimum density requirements of the R-4 zone classification. All lots shall meet the minimum dimensional requirements of the R-4 zone classification or shall be as shown on the face of the approved preliminary plat, whichever is larger, except that minor revisions to the plat which do not result in substantial changes may be approved at the discretion of the Department of Development and Environment Services. Condition Noted. Any/all plat boundary discrepancy(ies) shall be resolved to the satisfaction of DDES prior to the submittal of the final plat documents. As used in this condition, "discrepancy" is a boundary hiatus, an overlapping boundary or a physical appurtenance which indicates an encroachment, lines of possession or a conflict of title. 4. The applicant must obtain final approval from the King County Health Department. Condition Noted. 5. All construction and upgrading of public and private roads shall be done in accordance with the King County Road Standards established and adopted by Ordinance No. 11187, as amended (1993 KCRS). All roads have been designed per the 1993 KCRS. 6. The applicant must obtain the approval of the King County Fire Protection Engineer for the adequacy of the fire hydrant, water main, and fire flow standards of Chapter 17.08 of the King County Code. Plans have been submitted to the Fire Marshal. All future residences constructed within this subdivision are required to be sprinklered (NFPA 13D) unless the requirement is removed by the King County Fire Marshal or his/her designee. The Fire Code requires all portions of the exterior walls of structures to be within 150 feet (as a person would walk via an approved route . around the building) from a minimum 20-foot wide, unobstructed driving surface. To qualify for removal of the sprinkler requirement, driving surfaces between curbs must be a minimum of 28 feet in width when parking is allowed on one side of the roadway, and at least 36 feet in width when parking is permitted on both sides. The road width requirement applies to both on-site access and roads accessing the subdivision. Storm Drainage 7. Final plat approval shall require full compliance with the drainage provisions set forth in King County Code 9.04. Compliance may result in reducing the number and/or location of lots as shown on the preliminary approved plat. Preliminary review has identified the following conditions of approval, which represent portions of the drainage requirements. All other applicable requirements in KCC 9.04 and the Job #01-047 August 7, 2008 Page 2-12 East Renton/Rosemonte -Technical Information Report Surface Water Design Manual (SWDM) must also be satisfied during engineering and final review. a. Drainage plans and analysis shall comply with the 1998 King County Surface Water Design Manual. DDES approval of the drainage and roadway plans is required prior to any construction. The drainage plans and analysis have been provided in compliance to the 1998 KCSWDM and applicable updates. b. Current standard plan notes and ESC notes, as established by DDES Engineering Review shall be shown on the engineering plans. Current standard plan notes and ESC notes have been provided on sheet 7. c. The following note shall be shown on the final recorded plat: "All building downspouts, footing drains, and drains from all impervious surfaces such as patios and driveways shall be connected to the pennanent storm drain outlet as shown on the approved construction drawings # on file with DDES and/or the Department of Transportation. This plan shall be submitted with the application of any building permit. All connections of the drains must be constructed and approved prior to the final building inspection approval. For those lots that are designated for individual lot infiltration systems, the systems shall be constructed at the time of the building pennit and shall comply with the plans on file." Condition Noted. d. Stonn water facilities shall be designed using the KCRTS level one flow control standard. Water quality facilities shall also be provided using the basic water quality protection menu. The size of the proposed drainage tracts may have to increase to accommodate the required detention volumes and water quality facilities. All runoff control facilities shall be located in a separate tract and dedicated to King County unless portions of the drainage tract are used for recreation space in accordance with KCC 21A.14. l 80. The stormwater facilities have been designed to a Level 1 flow control and basic water quality per the 1998 KCSWDM and are shown in dedicated tracts. e. The applicant has received approval for a drainage adjustment application regarding the proposed shared facility detention pond. The adjustment decision is contained within file number L04VOI03. During final review of the engineering plans, all applicable conditions of the adjustment approvals shall be satisfied. Condition noted. Please refer to a copy of the adjustment within the TIR for conditions of approval. f. As stated in the drainage adjustment decision, the detention pond shall be designed using the Level I flow control standard and basic water quality standards are required for design of the drainage facility. If a wet pond facility is provided for water quality, the design shall comply with the 3: I Job #01-047 August 7, 2008 Page 2-13 ) East Renton/Rosemonte -Technical Information Report flow length ratio as outlined on page 6-72 in the drainage manual. The detention pond has been designed per the 1998 KCSWDM. g. As required by Special Requirement No. 2 in the drainage manual, the I 00- year floodplain boundaries for the onsite wetlands shall be shown on the final engineering plans and recorded plat. Condition Noted. Access/Roads 8. The proposed subdivision shall comply with the 1993 King County Road Standards (KCRS) including the following requirements: a. During preliminary review the applicant submitted a road variance application (File No. L06V0042), regarding the sag vertical curve and substandard stopping sight distance along the plat frontage. In response to the variance application, the King County Road Engineer provided a decision letter dated June 20, 2006 which approved the variance based upon required illumination for the sag curve on l 48'h Ave SE. The final road improvements and design plans for the project shall demonstrate compliance with all applicable conditions of approval as stated in the variance decision. The vertical re- alignment is shown on sheets 14 and 15. b. 148th Avenue SE shall be improved along the frontage as an urban collector arterial including all design criteria from the road variance decision. In accordance with KCRS 2.02, the curb location shall be designed at 22-feet from the road crown to provide full width travel lanes and a bike lane. The preliminary design plan for Rosemonte shows road grading extending outside the right-of-way on the east side of 148th Ave SE. During final engineering review, the applicant shall acquire easements for any proposed construction on private property or provide an alternative design which is acceptable to King County for road construction within the existing right-of-way. If desired by the applicant, the road frontage improvements for Rosemonte may be satisfied by development of the East Renton plat. Please see sheets 14 and 15 for 148 1h Ave SE improvements. Easements are not required. c. The proposed loop road within the subdivision (SE I 18th St.) shall be improved as an urban subaccess street. SE 118 1h Street has been designed as a minor access street. d. Tract A shall be improved as a private joint use driveway serving a maximum of two lots. The serving lots shall have undivided ownership of the tract and be responsible for its maintenance. As specified in KCRS 3.0IC, improvements shall include an 18 foot paved surface and a minimum tract width of 20 feet. Drainage control shall include a curb or thickened edge on one side. Tract A has been designated as open space and a curb, gutter and sidewalk to the south along SE 119th Street. Job #01-047 August 7, 2008 Page 2-14 East Renton/Rosemonte -Technical Information Report e. Street trees shall be included in the design of all road improvements and shall comply with Section 5.03 of the KCRS. Street trees have been depicted on the landscape plans. f. Street illumination shall be provided along the plat frontage for arterial streets in accordance with KCRS 5.05. Illumination has been shown on sheet 23. g. The proposed road improvements shall address the requirements for road surfacing outlined in KCRS Chapter 4. As noted in section 4.0IF, full width pavement overlay is required where widening existing asphalt, unless otherwise allowed by King County. A note has been provided on the plans. h. 148th Ave SE is classified an arterial street which may require designs for bus zones and turn outs. As specified in KCRS 2.16, the designer shall contact Metro and the local school district to determine specific requirements. Metro and the school district have been contacted. 1. Modifications to the above road conditions may be considered by King County pursuant to the variance procedures in KCRS 1.08. Condition Noted. 9. All utilities within proposed rights-of-way must be included within a franchise approved by the King County Council prior to final plat recording. Condition Noted. 10. The plat plan for Rosemonte shows a retaining wall associated with 145th Ave SE which extends into the BSBL for the wetland buffer. During engineering review for East Renton, a revised road alignment and grading plan shall be provided which demonstrates that road construction within Rosemonte will comply with applicable sensitive area codes. The revised road design and grading plan may result in modification or loss of lots as shown on the preliminary plat. Alternatively, the applicant may seek approval to use buffer averaging as a means to revise the location of the buffer and BSLB to achieve code compliance. Condition Noted. 11. There shall be no direct vehicular access to or from 148th Ave SE from those lots which abut it. A note to this effect shall appear on the engineering plans and the final plat. The note has been provided on the Road and Storm plans. 12. Off-site access to the subdivision shall be over a full-width, dedicated and improved road which has been accepted by King County for maintenance. If the proposed access road has not been accepted by King County at the time of recording, then said road shall be fully bonded by the applicant of this subdivision. Condition Noted. 13. The applicant shall provide a safe walking access to Apollo Elementary School with urban improvements along the west side of 148th Ave NE to the existing crosswalk on the north side of SE I 17th St. This improvement includes urban frontage improvements along property frontage of the Plat of East Renton, north of SE I 19th Street, as well as urban improvements along frontage of Rosemonte and urban Job #01-047 August 7, 2008 Page 2-15 ) East Renton/Rosemonte -Technical Information Report improvements north to the existing crosswalk on the north side of SE l l 7'h St. Curb, gutter and sidewalk has been design on the west side of 148 1h Ave NE. In the event it is not practical to construct urban improvements on the west side of 148th Avenue Southeast extending to the existing crosswalk, a new crosswalk may be established south of Southeast I 17th Street and a safe walkway provided on the east side of 148th Avenue Southeast from the new crosswalk to the north side of Southeast I 17th Street. This alternative may use a graded surface on the east side of 148th Ave SE to ensure that school-age pedestrians are provided an acceptable-width walkway surface behind the curbing. The walkway shall be designed to the satisfaction of the school district and ODES. A crosswalk has been shown on the south side of 11 ?1h Street. Easements could not be obtained to provide otherwise. Mitigation/Impact Fees 14. The applicant or subsequent owner shall comply with King County Code 14.75, Mitigation Payment System (MPS), by paying the required MPS fee and administration fee as determined by the applicable fee ordinance. The applicant has the option to either: (I) pay the MPS fee at the final plat recording, or (2) pay the MPS fee at the time of building permit issuance. If the first option is chosen, the fee paid shall be the fee in effect at the time of plat application and a note shall be placed on the face of the plat that reads, "All fees required by King County Code 14.75, Mitigation Payment System (MPS), have been paid." If the second option is chosen, the fee paid shall be the amount in effect as of the date of building permit application. Condition Noted. 15. Lots within this subdivision are subject to King County Code 21A.43, which imposes impact fees to fund school system improvements needed to serve new development. As a condition of final approval, fifty percent (50%) of the impact fees due for the plat shall be assessed and collected immediately prior to the recording, using the fee schedules in effect when the plat receives final approval. The balance of the assessed fee shall be allocated evenly to the dwelling units in the plat and shall be collected prior to building permit issuance. Condition Noted. Wetlands 16. Preliminary plat review has identified specific requirements which apply to this project as listed below. All other applicable requirements from K.C.C. 21A.24 shall also be addressed by the applicant. a. The Class 2 wetland shall have a minimum SO-foot buffer of undisturbed vegetation as measured from the wetland edge. Onsite wetlands have been provided with buffers. Tracts and building setbacks are shown on the engineering plans. Job #01-047 August 7, 2008 Page 2-16 East Renton/Rosemonte -Technical Information Report b. Sensitive area tract(s) shall be used to delineate and protect sensitive areas and buffers in development proposals for subdivisions and shall be recorded on all documents of title of record for all affected lots. Condition Noted. c. Buffer width averaging may be allowed by King County if it will provide additional protection to the wetland/stream or enhance there functions, as long as the total area contained in the buffer on the development proposal site does not decrease. In no area shall the buffer be less than 65 percent of the required minimum distance. To ensure such functions are enhanced a mitigation plan will be required for the remaining on-site sensitive areas. An enhancement plan shall be submitted for review during engineering review. Buffer averaging has been shown on the plans as well as enhancement. Please see the Landscape plans for the enhancement plan. d. A 15-foot BSBL shall be established from the edge of buffer and/or the sensitive areas Tract(s) and shown on all affected lots. Onsite wetlands have been provided with buffers. Tracts and building setbacks are shown on the engineering plans. e. To ensure long term protection of the Sensitive Areas a split-railed fence ofno more than 4 feet in height shall be installed along the Sensitive Area Tract boundaries in the area of proposed lots. Sensitive Area signs shall be attached to the fence at no less than I 00 foot intervals. Sensitive Area signs have been shown on the landscape plans. g. If alterations of streams and/or wetlands are approved in conformance with K.C.C. 21A.24, then a detailed plan to mitigate for impacts from that alteration will be required to be reviewed and approved along with the plat engineering plans. A performance bond or other financial guarantee will be required at the time of plan approval to guarantee that the mitigation measures are installed according to the plan. Once the mitigation work is completed to a DOES Senior Ecologist's satisfaction, the performance bond may be replaced by a maintenance bond for the remainder of the five-year monitoring period to guarantee the success of the mitigation. The applicant shall be responsible for the installation, maintenance and monitoring of any approved mitigation. The mitigation plan must be installed prior to final inspection of the plat. Condition Noted. g. Prior to commencing construction activities on the site, the applicant shall temporarily mark sensitive areas tract(s) in a highly visible manner, and these areas must remain so marked until all development proposal activities in the vicinity of the sensitive areas are completed. Condition Noted. h. Job #01-047 August7,2006 During engineering plat review the applicant shall provide a hydrology analysis to demonstrate how the wetland hydrology maintained post-construction. wetland will be Page 2-17 ) East Renton/Rosemonte -Technical Information Report 1. Detention out-fall structures maybe permitted within the wetland/stream buffers, however, structures shall be located in the outer edge of the buffer, if possible. All buffer impacts shall be mitigated. Condition Noted. 17. Development authorized by this approval may require other state and/or federal permits or approvals. It is the applicant's responsibility to correspond with these agencies prior to beginning work on the site. Condition Noted. 18. During engineering review, the plan set shall be routed to the sensitive areas group to determine if the above conditions have been met. Condition Noted. Geo technical 19. The applicant shall delineate all on-site erosion hazard areas on the final engineering plans (erosion hazard areas are defined in KCC 21A.06.415). The delineation of such areas shall be approved by a DOES geologist. The requirements found in KCC 21A.24.220 concerning erosion hazard areas shall be met, including seasonal restrictions on clearing and grading activities. Condition Noted. 20. The geotechnical work for this project shall be accomplished iri accordance with recommendations presented in the geotechnical engineering report dated April 23, 2003 by Associated Earth Sciences, Inc. a. Structural fill placement shall be continuously monitored and approved in writing by the project geotechnical engineer or engineering geologist. b. After excavation and prior to structural fill or foundation placement, all bearing soils shall be inspected and approved in writing by an experienced geotechnical engineer or engineering geologist. c. Structural fill placed for improved areas such as pavements or floor slabs shall be compacted to at least 95 percent of the maximum dry density by ASTM test designation D-1557 (Modified Proctor) or as recommended by the project geotechnical engineer or engineering geologist. d. All pile foundation installations shall be continuously monitored by a registered geotechnical engineer or a licensed engineering geologist for compliance with an approved plan and the geotechnical report. Compliance and approval of the pile foundation installation shall be documented in a report to the King County site or building inspector. e. The location and height of any proposed rockeries or retaining walls shall be shown on the engineering plans. f. Job #01-047 August 7, 2008 Any created fill slope that is 40 percent or steeper and IO feet or greater in vertical height shall be subject to a SO-foot wide buffer plus a 15-foot wide setback area from its top, toe and sides. This buffer may be reduced to IO feet with a satisfactory evaluation by a registered geotechnical engineer or licensed engineering geologist. Page 2-18 ) East Renton/Rosemonte -Technical Information Report g. The applicant shall delineate all on-site erosion hazard areas on the final engineering plans (erosion hazard areas are defined in KCC 21A.06.415). The delineation of such areas shall be approved by a DDES geologist. The requirements found in KCC 21A.24.220 concerning erosion hazard areas shall be met, including seasonal restrictions on clearing and grading activities. Sensitive Area 21. The following note shall be shown on the final engineering plan and recorded plat: RESTRICTIONS FOR SENSITIVE AREA TRACTS AND SENSITIVE AREAS AND BUFFERS Dedication of a sensitive area tract/sensitive area and buffer conveys to the public a beneficial interest in the land within the tract/sensitive area and buffer. This interest includes the preservation of native vegetation for all purposes that benefit the public health, safety and welfare, including control of surface water and erosion, maintenance of slope stability, and protection of plant and animal habitat. The sensitive area tract/sensitive area and buffer imposes upon all present and future owners and occupiers of the land subject to the tract/sensitive area and buffer the obligation, enforceable on behalf of the public by King County, to leave undisturbed all trees and other vegetation within the tract/sensitive area and buffer. The vegetation within the tract/sensitive area and buffer may not be cut, pruned, covered by fill, removed or damaged without approval in writing from the King County Department of Development and Environmental Services or its successor agency, unless otherwise provided by law. The common boundary between the tract/sensitive area and buffer and the area of development activity must be marked or otherwise flagged to the satisfaction of King County prior to any clearing, grading, building construction or other development activity on a lot subject to the sensitive area tract/sensitive area and buffer. The required marking or flagging shall remain in place until all development proposal activities in the vicinity of the sensitive area are completed. No building foundations are allowed beyond the required 15-foot building setback line, unless otherwise provided by law. Condition Noted. Recreational Area 22. The plat design shall be revised to provide the minimum suitable recreation space consistent with the requirements ofK.C.C. 21A.14.180 and K.C.C. 21A. 14.190 (i.e., minimum area, as well as, sport court[s], children's play equipment, picnic table[s], benches, etc.), as shown on hearing exh. no. 26. Recreation plans, performance bond and homeowner's association will be provided. a. Job #01-047 August 7, 2008 A detailed recreation space plan (i.e., location, area calculations, dimensions, landscape specs, equipment specs, etc.) shall be submitted for review and Page2-19 Other East Renton/Rosemonte -Technical Information Report approval by DOES prior to or concurrent with the submittal of engineering plats. b. A performance bond for recreation space improvements shall be posted prior to recording of the plat. c. Modify the plat, as needed to comply with KCC 21A.14.180.F, as shown in hearing exh. no. 26 for the plat of East Renton (ODES File No. L02P0005). 23. A homeowners' association or other workable organization shall be established to the satisfaction ofDDES which provides for the ownership and continued maintenance of the recreation, open space and/or sensitive area tract(s), which combine usage of the recreation area of the plat of East Renton (ODES File No. L02P0005) and this plat, as shown in hearing exh. no. 26 for the plat of East Renton. A homeowner's association or other workable organization will be established by the applicant. 24. Street trees shall be provided as follows (per KCRS 5.03 and K.C.C. 21A.16.050): Street trees have been shown on the landscape plans as outlined below. a. Trees shall be planted at a rate of one tree for every 40 feet of frontage along all roads. Spacing may be modified to accommodate sight distance requirements for driveways and intersections. b. Trees shall be located within the street right-of-way and planted in accordance with Drawing No. 5-009 of the 1993 King County Road Standards, unless King County Department of Transportation determines that trees should not be located in the street right-of-way. c. If King County determines that the required street trees should not be located within the right-of-way, they shall be located no more than 20 feet from the street right-of-way line. d. The trees shall be owned and maintained by the abutting lot owners or the homeowners association or other workable organization unless the county has adopted a maintenance program. Ownership and maintenance shall be noted on the face of the final recorded plat. e. The species of trees shall be approved by DOES if located within the right-of- way, and shall not include poplar, cottonwood, soft maples, gum, any fruit- bearing trees, or any other tree or shrub whose roots are likely to obstruct sanitary or storm sewers, or that is not compatible with overhead utility lines. f. The applicant shall submit a street tree plan and bond quantity sheet for review and approval by DOES prior to engineering plan approval. Job #01-047 August 7, 2008 Page 2-20 ) g. h. ii. East Renton/Rosemonte -Technical Information Report The applicant shall contact Metro Service Plannin& at (206) 684-1622 to determine if 148th Ave SE is on a bus route. If 148 Ave SE is a bus route, the street tree plan shall also be reviewed by Metro. The street trees must be installed and inspected, or a performance bond posted prior to recording of the plat. If a performance bond is posted, the street trees must be installed and inspected within one year of recording of the plat. At the time of inspection, if the trees are found to be installed per the approved plan, a maintenance bond must be submitted or the performance bond replaced with a maintenance bond, and held for one year. After one year, the . maintenance bond may be released after DOES has completed a second inspection and determined that the trees have been kept healthy and thriving. A landscape inspection fee shall also be submitted prior to plat recording. The inspection fee is subject to change based on the current county fees. 25. The engineering plans for this project shall identify the location of any wells on the site and provide notes which address the requirements for the contractor to abandon the well(s) pursuant to requirements outlined in the Washington Administrative Code (WAC 173-160). Condition Noted. SEPA 26. The following have been established by SEPA as necessary requirements to mitigate the adverse environmental impacts of this development. The applicants shall demonstrate compliance with these items prior to final approval. (!.) To mitigate the significant adverse impact the plat of Rosemonte will have on the intersections of SR 9001148th Ave SE and SR 9001164th Ave SE, the applicant shall install, either individually or in conjunction with other development projects in this area, the following improvements at the SR 9001148th Ave intersection: o A traffic signal, and o Eastbound and westbound left tum lanes The design for the SR 9001148th Ave intersection improvements shall be approved by the Washington State Department of Transportation (and by King County to the extent such improvements are located in County right-of-way). In addition, at a minimum, the existing entering sight distance looking east for the north and south legs of the intersection (602 feet and 386 feet, respectively) shall not be reduced as part of the intersection improvements. Documentation shall be submitted to show this requirement is met. All construction work associated with the intersection improvements shall be completed between April l" and September 30 1 h. This seasonal restriction shall be clearly shown on the final engineering plans. In lieu of the installation of the above-noted intersection improvements prior to final plat approval, the applicant may post a financial guarantee with WSDOT which Job #01-047 August 7, 2008 Page 2-21 '\ ) East Renton/Rosemonte -Technical Information Report assures the installation of these improvements within two years of the recording of Rosemonte. In this event, intersection improvement design must be approved by WSDOT prior to King County approval of the engineering plans for Rosemonte. If the above-noted intersection improvements have already been made by others prior to the recording of Rosemonte, or a financial guarantee has been posted by others which assures the installation of these improvements, then the applicant for Rosemonte shall pay a pro-rata share dollar amount to the developer who has made the improvements or "bonded" for the improvements, in an amount proportional to the impacts of Rosemonte. The pro-rata share dollar amount to be paid shall be set by WSDOT, and documentation shall be provided by the Rosemonte applicant to the King County Land Use Services Division to show this payment has been made, prior to final plat recording. The pro-rata dollar amount to be paid shall be based on the following: o The final Rosemonte lot count o The trip distribution for Rosemonte o The total trips contributed to the intersection of SR 900.1481h Ave by the plats of Aster Park (LOOP0024), Stone Ridge 9L99P3008), East Renton (L02P0005), Shamrock (L02POOl4), Rosemonte (aka Ironwood- L03P0018), Martin (L05P0019) and any future land use applications submitted to King County for which compliance with the King County Intersection Standards (KCC 14.80) is required at either the SR 900/l 48 1h Ave intersection, or the SR 9001164th Ave High Accident Location. In the event that either King County or WSDOT adopts a formal "latecomer's" system prior to final plat recording, that system may be followed in lieu of the approach described above, at the discretion of the applicant, as long as at a minimum there is a financial guarantee which assures the above-noted intersection improvements will be installed within two years of the date of recording of the plat of Rosemonte. [Comprehensive Plan Policy T-303 and King County Code 21A.28.060A) (2.) Documentation shall be provided to demonstrate to the satisfaction of WSDOT that stopping sight distance (360 feet) is available on the east leg of the SR 900/l 48th Ave intersection. The intersection shall be modified by the applicant, if necessary, so that this stopping sight distance requirement is met on the east leg. In addition, the applicant shall clear vegetation within the right-of-way along SR 900, east of 148th Ave., to maximize the entering sight distance for the north and south legs of the intersection. [Comprehensive Plan Policy T-303 and King County Comprehensive Policy T-303 and King County Code 21A.28.060A] The SEPA condition is under construction by others. Job #01-047 August7,2008 Page 2-22 ) East Renton/Rosemonte -Technical Information Report 2.2 Core Requirements 2.2.1 Core Requirement #1: Discharge at the Natural Location The site has two drainage basins, one that generally drains towards the northwest and the other that drains to the west. A wetland occupies the western portion of the site where the two basins combine then flows to the north through Honey Dew (Honey) Creek. The site generally slopes to the west from 148th Ave SE down towards Honey Dew Creek at approximately 5-15%. One drainage facility is proposed for the entire site. The pond is to be located in the northeast comer of the site. Please refer to the Level I Downstream Analysis in Section 3 for a complete description of the discharge points of the site. 2.2.2 Core Requirement #2: Offsite Analysis Please see Section 3 -Level I Downstream Analysis. 2.2.3 Core Requirement #3: Flow Control See Section 4 -Flow Control and Water Quality Facility Design. 2.2.4 Core Requirement #4: Conveyance System Please see Section 5 -Conveyance System Analysis and Design. 2.2.5 Core Requirement #5: Erosion and Sediment Control Please see Section 8 -TESC Analysis and Design. 2.2.6 Core Requirement #6: Operations and Maintenance The designed drainage systems and facilities will be publicly maintained. 2.2.7 Core Requirement #7: Bonds and Liability Bond Quantity Work Sheets and Liability insurance will be provided at the end of the review process. Job #01-047 August 7, 2008 Page 2-23 East Renton/Rosemonte -Technical Information Report 2.2.8 Special Requirement #1: Other Adopted Area-Specific Requirements 2.2.8.1 Critical Drainage Areas Maps from the King Country Sensitive Areas Folio show that the site is not in a sensitive drainage area with regard to aquifer protection zones, seismic hazards, coal mine hazards, erosion hazards, landslide hazards, or the I 00-year floodplains. The 1990 King County Wetland Inventory did not list the wetland on this property. The existing wetland is located along the western portion of the site and is not to be disturbed with a 32.50' buffer. The 1987 Basin Reconnaissance Program did not list Honey Dew Creek in any of its basin reconnaissance data. Please see Section 3 -Offsite Analysis for a copy of the King County Sensitive Area Maps. 2.2.8.2 Master Drainage Plan Not applicable. 2.2.8.3 Basin Plans According to the King County Basin Reconnaissance Program, the site is located within the May Creek Sub-basin of the Cedar River Drainage Basin. Please see Section 3 -Offsite Analysis for a copy of the King County Basin Map. 2.2.8.4 Lake Management Plans Not applicable. 2.2.8.5 Shared ]Facility Drainage Plans Not applicable. 2.2.9 Special Requirement #2: Floodplain/Floodway Delineation Not applicable. 2.2.10 Special Requirement #3: Flood Protection Facilities Not applicable. Job #01-047 August 7, 2008 Page 2-24 East Renton/Rosemonte -Technical Information Report 2.2.11 Special Requirement #4: Source Controls Not applicable. This project is not a commercial, industrial, multifamily or a redevelopment of a commercial, industrial or multifamily project. 2.2.12 Special Requirement #5: Oil Control Not applicable. This project is not a commercial or industrial site. Job#01-047 August 7, 2008 Page 2-25 • ~) ~-/ · .. , April 5, 2007 OFFICE OF TIIIE HEARING EXAMINER RlEPOJllT ANll> ]l)D!CllSRON I KING COUNTY, WASHINGTON 400 Yesler Way, Room 404 Seattle, Washington 98104 Telephone (206) 296-4660 FBCBimile (206) 296-l 6S4 Email: hearex@metrokc.gov SUBJECT: Department of Development and F.nvironmcntal Services File No. L021POOOS Pl"Op<llMld Onlinamle no. 2037-0010 Location: Applicant: lMBT JmN'll'ON Preliminary Plat Application West of 148th Avenue Southeast at approximately Southeast 120th StJeet, Renton Cam West Real Bstate Dev., Inc. repruented by~ Jolmo, Attorney Johna Monroe Mitsunap 1601 -114th Ave. SB,# 110 Bellevue, Washington 98004 Telephone: (42') 467-9960 Facaimile: ( 42') 4S 1-2818 King County: Depaltment of Development aud Enviromnental Services (DDES) represented by Konni Seborer 900 Oakesdale Avenue Southwest Renton, Waablngton 98055-1219 Telephone: (206) 296-7114 Facsimile: (206) 296-70S I SUMMARY OF RECOMMENDATIONS/DECISION: Department's Preliminary Recommendation: Department's Final Recommendation: Examiner's Decision: EXAMINER PROCEEDINGS: Approve subject to conditions Approve subject to conditions (modified) Approve subject to conditions (modified) Hearing Opened: March 22, 2007 Continued for Administrative Purposes: March 22, 2007 Hearing Closed: March 23, 2007 The public hearing on the proposed subdivision of East Renton was conducted concurrently with the L02P000S-East Renton 2 public hearing on the proposed subdivision ofRosemonte (DOES File No. L03P0018). Participants at the public hearing and the exhibits offered and entered are listed in the attached minutes. At 12:31 p.m. the hearing was continued for administrative purposes, to allow for the submission of proposed exh. no. 29, that would set forth the final recommendation of the department concerning revisions to recommended conditions #'s 6, 20, 21 and 22. Exhibit 29 was received by the Hearing Examiner on March 22, 2007, and the hearing was declared closed on March 23, 2007 A verbatim recording of the hearing is available in the office of the King County Hearing Examiner. ISSUES AND TOPICS ADDRESSED: • • • Futun, developmml tract Red-tailed hawks nest Safe walldlJ3 conditions SUMMARY: • • • Recreation area Wedl!nd buffin Surface water drainage Thepropoaed subdivision of 17.01 acres into 66 lots in the urban area is approved subject to conditions. FINDINGS, CONCLUSIONS & DECISION: Having reviewed the record in this matter, the Examiner now mabs and enters the following: {(_,1 FINDINGS: ' / 1. Gemell'lll Wormodon: Developer: Engineer: STR: Location: Zoning: Acreage: Number of Lots: Density: Lot Size: Proposed Use: Sewage Disposal: Camwaat Real Batato DGvolopment, Inc. 9720 NB 120° Place, Suite 100 Klrldaml, WA !III034 ContFct: San Slatten 425-825-19SS Triad Asaociates 12112 115111 Ave NE Klrldaud, WA !18034 Contact: Oerry Buck 425-821-8448 10-23-05 West of 148th Ave SE at approximately SE120'h St. Parcel-1023059023 R-4 17.01 acres 66 Approximately 3.9 units per acre Approximately 5,000 square feet in size Single Family Detached Dwellings City of Renton (L; . __ ::' I I~ L02P0005-East Renton 3 Water Supply: Fire District: School District: Water District # 90 .. City of Renton Issaquah School District Complete Application Date: April 17, 2002 2. Except as modified herein, the facts set forth in the King County Land Use Services Division's preliminary report to the King County Hearing Examiner for the March 22, 2007, public hearing are found to be correct and are incorporated herein by this reference. The LUSD staff recommends approval of this subdivision, subject to conditions. 3. Development of this subdivision may affect, and lead to the abandonment of, a red-tailed hawka neat on the subject property. The red-trail hawk is not an endangered or threatened species, and no protegtion of the red-tail hawk is afforded by law or the King County Code within the dealpted IJlban area of King Couoly. 4. The applicant bas proposed the establisbrnml of Tract E as a "filture development" tract. ODES d@kmniaed that there is no reasonable l!CCCS8 available to Tract E that would not croas wetland or wetlmld buffer. At the hearing the applicant abandoned its request to designate Tract E as a "fillme developmeot" tract, and proposes to establish that tract as recreation area, to be coonected by IJaiJ with the deaipted recreation/detention Tract O within this subdivision and adjacent to the proposed plat ofRosemuote. 5. Tho applicant bas submitted a revised recreation plan fur this subdivision and the adjacent plat of Rosemonte ( exh. 26). This plan provides adequate area within Tracts C, 0 and E and within the ptoposed recreation tract aml trail within Rosemonte to serve these plats jointly with well collCll!ved amenities for recreation aml open space, COD8ialent with the requlrementa of the King County Code. To the ctmt that a portion of the recreation area necessary to meet the requirements for the plat of Roeemonte is located on the East Renton property, that can be correeted by boundary line acljualment or recording the two plats as a single plat, if DOES determines that it is necesaary to do so. 6. Wetland buffers within this subdivision will need to be modified, utilizing the buffer averaging provisions of the critical areas code, to acc:omoxvlate the proposed alignment of 145th Avenue Southeast in the vicinity of the north property line, and adding buffer to mitigate the impacts of the proposed trail corridor within Tract F (between Tracts E and 0), in accordance with the provisions ofKCC 21A.24.045.D.47.b. 7. The proposed subdivision will provide for safe walking conditions for students who will walk to Apollo Elementary School on southeast 117th Street by constructing urban improvements to 148th A venue Southeast from the plat to Southeast 117th Street. A school crosswalk ( crossing 148th Avenue Southeast) is located on the north side of Southeast 117th Street, where an existing walkway is used by students to travel along the north side of Southeast 117th Street east from 148th Avenue Southeast to the school. This crosswalk also serves students walking from the area north of Southeast I 17th Street. Consequently, the crosswalk should be maintained on the north side of Southeast I 17th Street unless it is physically impractical to do so because of constraints resulting from the topography within the right-of-way for 148th Avenue Southeast, south of Southeast I 17th Street. If those constraints preclude extending curb, gutter and sidewalk from the l:J L02P0005-East Renton 4 plat of East Renton to the north side of Southeast I 17th Street, the crosswalk can be relocated to the south, and improvements made on the east side of 148th Avenue Southeast to Southeast I 17th Street. 8. The conceptual review of drainage plans has shown that there are no downstream impacts likely to occur from development of the subject property if Level I flow control and basic water quality treatment improvements are designed and constructed in accordance with the I 998 King Cowity Drainage Manual. The final drainage plan will include calculations to assure that the capacity of drainage facilities and discharge rates will be consistent with those flow control standards . • CONCLUSIONS: 1. If approved subject to the conditions recommaided below, the proposed subdivision will comply with the goals and objectives of the King County Compn,heasivo Plan, subdivision and zoning codes, and other official land use CO!llrola and policies of King County. 2. If approved subject to the conditions recommended below, this proposed subdivision will make lij)jliopliate provision for the public health, BBfety and general weliiire, and for open spaces, drainage ways, streeta, other public ways, transit stops, potable water supply, sanitary waste, parlm and recreatinn, playgsounda, schools and school grounds and safe walking conditions for mrdaits who only wallt to sc:hool; and it will serve the public use and interest. 3. The conditions for final plat approval recommended below are in the public interest and are reasonable and proportionate requiremeuta necessary to roitipte the impacts of the development upontbe~ 4. The dedications of land or Cl88fflllflllts within and IKljacent to the proposed plat, as required for fins) plat approval or as shown on the proposed pre1iroinary plat submitted by the Applicant on March 17, 2006 and the conceptual recreation plan submitted M-11 22, 2007 ( exh. 26), are reasonable and necesaary as a direct result of the development of this proposed plat, and are proportionate lo the impacts of the development. S. No provisions are requinxl to be made by this subdivision for the protection of the red-tail hawks nest(s) on the site. 6. The proposed future development designation for Tract E has been withdrawn by the applicant, and that tract shall be a portion of the designated recreation area for the currenl development. 7. 8. The proposed conceptual recreation plan submitted as exh. no. 26 is a reasonable and appropriate plan to serve the plats of East Renton and Rosemonte jointly. Minor alterations may be made in the final design and review by DOES, and boundary adjustments, if necessary, may be made to comply with provisions of KCC 21 A.14.180-200. Revisions to the wetland buffers will be necessary to comply with the provisions of the King County Critical Areas Code, to permit construction of 145th Avenue Southeast in the vicinity of the north property line and to mitigate the impacts of the trail coMecting Tracts E and 0. L02P0005-East Renton 5 9. In order to provide for safe walking conditions for students walking from this development to Apollo Elementary School, urban improvements must be made to 148th Avenue Southeast north from the proposed plat to the north side of Southeast I 17th Street. These improvements should be msde to the west side of 148th Avenue Southeast to the extent it is feasible to do so. In the event it is not practical to construct improvements extending to the existing crosswalk located at the north side of Southeast I 17th Street, a crosswalk msy be established south of Southeast I 17th Street and a safe walkway provided on the east side of 148th Avenue Southeast from the new crosswalk to the north side of Southeast I 17th Street. I 0. Calculations for surfilce water detention facilities shall assure that the n:lease of storm water from the site does not exceed the rates allowed by the 1998 King County Drainage Manual for achieving Level I flow control. DECISION: The proposed prellrnioary plat of East Renton, BB revised and received on March 17, 2006, is approved, subject to the following conditiona of final plat approval: I. Compliance with all platting provisions of Title 19A of the King County Code. r( / 2. All persona having BO ownership interest lo the subject property shall sign on the face of the final plat a dedication that includes the 1aoguage set forth lo King County Council Motion No. 5952. 3. The plat shall comply with the bBBe density and mioiroum density requirements of the R-4 zone clasaiflMtion. All lots shall meet the roini!Dllro dlmeoaioDBI requirement& of the R-4 zone classification or shall be BB shown on the lice of the approved pn,limioary plat, whichever is larger, except that minor reviaions to the plat which do not result io subsleotial changes may be approved at the discrelion of the Department of Development and Environment Services. Any/all plat boundary discrq,ancy(ies) shall be resolved to the satisfaction of DDES prior to the submittal of the final plat docwneots. As used lo this condition, "discrepancy" is a boundary hiatus, BO overlapping boundary or a physical appurtenance which indicates an encroachment, lines of possession or a conflict of title. 4. The applicant must obtain final approval from the King County Health Department. S. All construction and upgrading of public and private roads shall be done in accordance with the King County Road Standards established and adopted by Ordinance No. 11187, as amended (1993 KCRS). (Also see conditions 8 and 24.) .... ,. L02P0005-East Renton 6 6. The applicant must obtain the approval of the King County Fire Protection Engineer for the adequacy of the fire hydrant, water main, and fire flow standards of Chapter 17 .08 of the King County Code. All future residences constructed within this subdivision are required to be sprinklered (NFPA l3D) unless the requirement is removed by the King County fire Marshal or his/her designee. The Fire Code requires all portions of the exterior walls of structures to be within I 50 feet (.o.u person would walk yia an IIPJ)fOYed route around the buHdjmil from a minimum 20-foot wide, unobstructed driving surface. To qualify for removal of the sprinkler requirement, driving surfaces between curbs must be a minimum of 28 feet in width when pBlking is allowed on one side of the roadway, and at least 36 feet in width when parking is permitted on both sides. The road width requirement applies to both on-site access and roads aa:es•ing the subdivision. 7. Final plat approval ahall require full compliance with the drainage provisions set forth in King County Code 9.04. Compllaoco may result in ralucing the number and/or location of lots 88 shown on the prelimlDary approved plat. Pn,Jlminary review has identified the following conditiooa of approval. wbich represent portions of the drainage n,quirements. All other applicable requirements In KCC 9.04 and the Surface Water Design Manual (SWDM) must also be satisfied during engineering and final review. a. Drainage plans and analysis ahall comply with the 1998 King County Surface Water Design Manual: DDES approval of the drainage and roadway plans is required prior to any construction. b. Cumm1 standard plan notes and ESC notes, 88 established by DDBS Engineering Review ahall be shown on the engineering plans. c. The following note ahall be shown on the final recorded plat: d. • All building downspouts, footing drains, and drains from all impervious surfaces such as patios and driveways ahall be connected to the permanent storm drain outlet 88 shown on the approved construction drawings # on file with DDES and/or the Department of Transportation. This plan shall be submitted with the application of any building permit. All connections of the drains must be constructed and approved prior to the final building inspection approval. For those lots that are designated for individual lot infiltration systems, the systems shall be constructed at the time of the building permit and shall comply with the plans on file." Storm water facilities shall be designed using the KCRTS level one flow control standard. Water quality facilities shall also be provided using the basic water quality protection menu. The size of the proposed drainage tracts may have to increase to accommodate the required detention volumes and water quality facilities. All runoff control facilities shall be located in a separate tract and dedicated to King County unless portions of the drainage tract are used for recreation space in accordance with KCC 21A.14.180. L02P0005-East Renton 7 e. The applicant has received approval for two drainage adjustment applications regarding designs for the discharge of storm water and a shared facility detention pond. The adjustment decisions are contained within file numbers L02V0089 and L04VO 103. During final review of the engineering plans, all applicable conditions of the adjustment approvals shall be satisfied including requirements for the shared facility located offsite within the plat of Roaemonte. f. As stated in the drsinage adjustment decision, the offsite drainage pond shall be designed using the Level I flow control standard. Basic water quality standards are also required for design of the facility. If a wet pond facility is provided for water quality, the design shall comply with the 3: I flow length ratio as outlined on page 6-72 in the drsinage mam,al. For evahlation of the onsite storm vault and the offilite detention pond, a soils report sball be prepared by a geotocbnical enginccr to evaluate the soils and groundwater conditions. g. For any proposed bypass of storm water from the flow control facility, the final drainage designs shall comply with applicable design requirements in the drainage manual as outlined on pages 1-36 and 3-52. h. As required by Special Requirement No. 2 in the drainage manual, the I 00-year floodplain boundaries for the onsite wetlands sball be shown on the final engineering plans and recorded plat. Accesa and Roodo 8. The proposed subdivision shall comply with the 1993 King County Road Standards (KCRS) including the following Rqllirements: a. During preliminary review the applicant submitted a road variance application (File No. b. L03V0049), regarding the crest vertical curve and substandard stopping sight distance along tho plat frontage. In response to the variance application, the King County Road Engineer provided a decision letter dated October 20, 2004 which approved the variance based upon specific design criteria for constructing 148111 Ave SE. As noted in the variance decision, the crest curve on 148111 Ave SE must be reconstructed to provide 455 feet of stopping sight distance based upon design criteria with a 2-foot target. The final road improvements and design plans for the project sball demonstrate compliance with all applicable conditions of approval as stated in the variance decision. 1481h A venue SE shall be improved along the frontage as an urban collector arterial including all design criteria from the road variance decision. In accordance with KCRS 2.02, the curb location shall be designed at 22-feet from the road crown to provide full width travel lanes and a bike lane. The preliminary design plans for East Renton shows road grading extending outside the right-of-way on the east side of 14S'h Ave SE. During final engineering review, the applicant shall acquire easements for any proposed construction on private property or provide an alternative design which is acceptable to King County for road construction within the eidsting right-of-way. c. The project entry road to 148 1h Ave SE shall be improved as an urban neighborhood L02P0005-East Renton 8 collector. As shown on the preliminary plat, the required right-of-way width is 56 feet. · d. The proposed roads within the subdivision shall be improved using urban design standards and in accordance with the street classifications shown on the preliminary plat map. e. Tract D shall be improved as a private joint use driveway serving a maximum of two lots. The lots served shall have undivided ownership of the tract and be responsible for its maintenance. As specified in KCRS 3.0 IC, improvements shall include an 18 foot paved aurfiice and a minimum tract width of 20 feet. Drainage control shall include a curb or thickened edge on one side. f. Street lree8 shall be included in the design of all road improvements and shall comply with Section S.03 of the KCRS. g. Street illumination shall be provided along the plat frontage and at intenections with arteriaJa in accordance with KCRS S.OS. b. i. The proposed road improvements shall address the requircmcnls for road surfacing outlined in KCRS Chapter 4. As noted in section 4.0IF, full width pavement overlay is requin,d where widening existing asphalt, unless otherwise approved by King County. 148"' Ave SE is cla88ified as an arterial street which may require deaigns for bus zonea and tum outs. As specified in KCRS 2.16, the designer shall contact Metro and the local school district to determine specific requirements. j. Modifications to the above road conditions may be considered by King County purauant to the variance procedures in KCRS 1.08. 9. All utilities within proposed rights-of-way must be included within a franchise approved by the King County Council prior to 6naJ plat recording. JO. The site plans for East Renton show the northerly road stub for 1451t1 Ave SE which may extend into the wetland buffer and associated setback within the Rosemont plal During engineering review for East Renton, a revised road alignment and grading plan shall be provided which demonstrates that road construction within Roscmonte will comply with applicable sensitive area codea. The revised road design and grading plan may result in modification or loss of lots as shown on the preliminary plat. Alternatively, the applicant may seek approval to use buffer averaging as a means to revise the location of the buffer and BSLB to achieve code compliance within Roscmonte. 11. There shall be no direct vehicular access to or from 148 1h Ave SE from those lots which abut it. 12. A note to this effect shall appear on the engineering plans and the final plat. The applicant shall provide a safe walkinf access to Apollo Elementary School with urban improvements along the west side of 148 Ave NE to the existing crosswalk on the north side of SE I 17th St. This improvement includes urban frontage improvements along property frontage of the Plat of East Renton, urban improvements along frontage of Rosemonte and urban L02P0005-East Renton 9 13. improvements north to the existing crosswalk on the north side of SE 1171h ST. (It is noted that the adjoining plat of Rosemonte also will be subject to urban frontage requirements and urban improvements north to the existing crosswalk on the north side of SE 1171h ST.) In the event it is not practical to construct urban improvements on the west side of 148th Avenue Southeast extending to the existing crosswalk, a new crosswalk may be established south of Southeast I 17th Street and a safe walkway provided on the east side of 148th Avenue Southeast from the new crosswalk to the north side of Southeast I 17th Street. This alternative may use a graded surface on the east side of 148th Ave SE to ensure that school-age pedestrians are provided an acceptable-width walkway surface behind the curbing. The walkway shall be designed to the satisfaction of the school district and DOES. The applicant or subsequent owner shall comply with King County Code 14. 7S, Mitigation Payment System (MPS), by paying the requued MPS fee and administration fee as determined by the applicable fee ontimnce. The applicant baa the option to eilhcr. (I) pay the MPS fee at the final plat recording. or (2) pay the MPS fee at the time of building permit issuance. If the first option is chosen, the fee paid shall be the fee in effect at the lime of plat application and a note sbaJI be placed on the lace of the plat that reads, "All fees rcquifflCI by King County Code 14. 7S, Mitigation Payment System (MPS), have been paid." If the second option is chosen, the fee paid sbaJI be the amount in eff'cct as of the date of building permit application. 14. Lota within this subdivision are subject to King County Code 2 IA43, which imposes impact fees to tbnd school system improvements needed to serve new developmait. As a condition of final approval, fifty percen1 (SO%) of the impact fees due for the plat shall be assessed and collected immediately prior to the recording. llSUIIJ the fee schedules in effect when the plat receives final approval. The balance of the assessed fee shall be allocated evenly to the dwelling uni ta in the plat and shall be collected prior to building permit issuance. Wetlonda 15. Pteliminary plat review has identified specific rcquirements which apply to this project as listed below. All other applicable rcquiremonts from K.C.C. 21A.24 shall also be addressed by the applicant. a. The Class 2 wetland shall have a minimum SO-foot buffer of undisturbed vegetation as measured from the wetland edge. b. Sensitive area tract(s) shall be used to delineate and protect sensitive areas and buffers in development proposals for subdivisions and shall be recorded on all documents of title of record for all affected lots. (\ . J '--. ___ ,.. L02P0005-East Renton IO c. Buffer width averaging may be allowed by King County if it will provide additional protection to the wetland/stream or enhance their functions, as long as the total area contained in the buffer on the development proposal site does not decrease. In no area shall the buffer be less than 65 percent of the required minimum distance. To ensure such functions are enhanced a mitigation plan will be required for the remaining on-site sensitive areas. An enhancement plan shall be submitted for review during engineering review. d. A IS-foot BSBL shall be established from the edge of buffer and/or the sensitive areas Tract(s) and shown on all affected lots. e. To enaure long term protection of the Sensitive Areas a split-railed fence of no more than 4 feet in height shall be inatalled along the Sensitive Area Tract boundaries in the area of propoaed lots. Sllll8itive Area sip shall be attached to the fence at no less than 100 foot intervals. f. If alterationa of streams and/or wetlands are approved in conformance with K.C.C. 21 A24, then a detailed plan to mitigate for impacts from that alteration will be required to be reviewed and approved along with the plat engineering plana. A perfonuance bond or other financial guarantee will be required at the time of plan approval to guarantee that the mitigation measures are installed according to the plan. Once the mitigation work is completed to a DDBS Senior Ecologist's satisfaction, the performance bond may be replaced by a maintenance bond for the remainder of the fivo-year monitoring period to guarantee the 8IICCC8S of the mitigation. The applicant shall be responsible for the installation, maintenance and monitoring of any approved mitigation. The mitigation plan must be inatalled prior to final inspection of the plat. g. Prior to commencing COllstJUction activities on the site, the applicant sball temporarily mark sensitive areas tract(&) in a bighly visible manner, and these areas must remain so marked until all development proposal activities in the vicinity of the sensitive areas are completed. h. During engineering plan review the applicant shall provide a wetland hydrology analysis to demonatrate how the wetland hydrology will be maintained post-construction. i. Detention out-fall structures maybe permitted within the wetland/stream buffers, however, structures shall be located in the outer edge of the buffer, if possible. All buffer impacts shall be mitigated. ' 16. Development authorized by this approval may require other state and/or federal permits or approvals. It is the applicant's responsibility to correspond with these agencies prior to beginning work on the site. 17. During engineering review, the plan set shall be routed to the sensitive areas group to determine if the above conditions have been met. ,( / \ ,, -J L02P0005-East Renton n Geotecbnlcal 18. The applicant shall delineate all on-site erosion hazard areas on the final engineering plans (erosion hazard areas are defined in KCC 21A.06.415). The delineation of such areas shall be approved by a DOES geologist. The requirements found in KCC 21A.24.220 concerning erosion hazard areas shall be met, including seasonal restrictions on clearing and grading activities. Semltfve Area 19. The following note shall be shown on the final engineering plan and recorded plat: Other RESTRICTIONS FOR SENSITNE AREA TRACTS AND SENSITIVE AREAS AND BUFFERS Dedication of a sensitive area ttact/8CD8ltive area and buffer conveys to the public a beneficial interest in the land within the tract/sensitive area and buffer. This interest includes the preservation of native vegetation for all pwposes that benefit the public health, safety and · welfare, including control of surface water and erosion, maintenance of slope stability, and protection of plant and animal babitaL The scnsitive area tract/scnsitive area and buffer imposes upon.all pre8CIII and future owners and occupiers of the land subject to the tract/sensitive area and buffer the obligation, enfon:eable on behalf of the public by King County, to leave undisturbed all trees and other vegetation within the tract/sensitive area and buffer. The vegetation within the tract/sensitive area and buffer may not be cut, pnmcd, covered by fill, removed or damaged without approval in writing from the King County Department of Development and Environmental Services or its successor agency, unless otherwise provided by law. The common boundary between the tract/sensitive area and buffer and the area of development activity must be IDIUbd or otherwise Oagged to the satisfaction of King County prior to any clearing. grading, building construction or other development activity on a lot subject to the sensitive area ttact/aensitive area and buffer. The required marking or Oagging shall remain in place until all development proposal activities in the vicinity of the sensitive area are completed. No building foundations are allowed beyond the required 15-foot building setback line, unless otherwise provided by law. 20. The plat design shall be revised to provide the minimum suitable recreation space consistent with the requirements ofK.C.C. 21A.14.180 and K.C.C. 21A. 14.190 (i.e., minimum area, as well as, sport court(s], children's play equipment, picnic table[s], benches, etc.), as shown on hearing exh. no.26. a. b. A detailed recreation space plan (i.e., location, area calculations, dimensions, landscape specs, equipment specs, etc.) shall be submitted for review and approval by DOES prior to or concurrent with the submittal of engineering plats. A performance bond for recreation space improvements shall be posted prior to recording of the plat. ~) ( __ / L02P0005-East Renton 12 21. Tract E shall be designated for recreational area, with an approved trail (across wetland buffers) extending from the recreational Tract G and functioning as an extension of recreation from Tract G. Plans for the tract -designation and design, shall comply with codes and shall be to the satisfaction of ODES prior to engineering approval. 22. A homeowners' association or other workable organization shall be established to the satisfaction ofDDES which provides for the ownership and continued maintenance of the recreation, open space and/or sensitive area tract(s) which combines usage of recreation area within L03POOl 8, the plat of Rosemonte, pursuant to hearing exh. no. 26. (See condition no. 25.) 23. Street trees shall be provided as follows (per KCRS 5.03 and K.C.C. 21A.16.050): a. Trees shall be planted at a rate of one tree for every 40 feet of frontage along all roads. b. C. d. e. f. g. h. Spacing may be modified to accommodate sight distance requirements for driveways and intarsections. Trees shall be located within the street right-of-way and planted in accordance with Drawing No. S-009 of the 1993 King County Road Standards, unless King County Department of Transportation determines that trees should not be located in the ~ right-of-way. lfKing County determines that the required street trees should not be located within the right-of-way, they shall be located no more than 20 feet from the street right-of-way line. 1bc trees shall be owned and maintained by the abutting lot owners or the homeowners IIJl80Ciation or other worbble orpnization unless the county bas adopted a maintenance prounun. Ownership and maintenance shall be noted on the face of the final recorded plat. The species of trees shall be approved by ODES if located within the right-of-way, and shall not include poplar, cottonwood, soft maples, gum, any fruit-bearing trees, or any other tree or shrub whose roots are likely to obstruct sanitary or storm sewers, or that is not compatible with overhead utility lines. The applicant shall submit a street tree plan and bond quantity sheet for review and approval by DOES prior to engineering plan approval. The applicant shall contact Metro Service Planning at (206) 684-1622 to determine if 148th Ave SE is on a bus route. If 148th Ave SE is a bus route, the street tree plan shall also be reviewed by Metro. Toe street trees must be installed and inspected, or a performance bond posted prior to recording of the plat. If a performance bond is posted, the street trees must be installed and inspected within one year of recording of the plat. At the time of inspection, if the trees are found to be installed per the approved plan, a maintenance bond must be submitted or the performance bond replaced with a maintenance bond, and held for one year. After one year, the maintenance bond may be released after DOES has completed a L02P0005-East Renton 13 SIEPA secorid inspection and detennined that the trees have been kept healthy and thriving. i. A landscape inspection fee shall also be submitted prior to plat recording. The inspection fee is subject to change based on the current county fees. 24. The following have been established by SEPA as necessary requirements to mitigate the adverse envirorunental impacts of this development. The applicants shall demonstrate compliance with these itcma prior to final approval. (I.) To mitipte the sigmficant adverse impact the plat of East Renton will have on the inleraections of SR 900/148" Ave SE and SR 900/164 111 Ave SE, the applicant shall iDstall, either individually or in coqjunction with other development projects in this area, the following improvementa at the SR 900/148 111 Ave intersection: o A traffic signs), and o Eastbound and westbound left turn lanes The design for the SR 900/148 111 Ave intersection improvementa shall be approved by the Washington State Depaalmelll ofTnmsportation (and by King Cowuy to the cir.tent such improvements are located in County right-of-way). In addition, at a minimum, the Cltistlng enlering sight distance looking east for the north and south legs of the intersection (602 feet and 386 feet, respectively) shall not be reduced aa part of the intersection improvementa. Documentation shall be submitted to show this requirement is met. All construction work aaaociated with the intersection improvementa shall be completed between April I" and September 30'2'. Thia seasonal restriction shall be clearly shown on the final engineering plans. In lieu of the installation of the above-noted intersection improvcmcnta prior to final plat approval, the applicant may post a fiuancial guarantee with WSDOT which assures the inatallation of these improvcmenta within two years of the recordlng of East Renton. In this event, intenection improvement design must be approved by WSDOT prior to King County approval of the en11U1eering plans for East Renton. If the abov•noted intersection improvemcnta have already been made by othen prior to the recording of East Renton, or a financial guarantee has been posted by others which assures the Installation of these improvcmcnta, then the applicant for East Renton shall pay a pro-rata share dollar amount to the developer who has made the improvements or "bonded" for the improvcmenta, in an amount proportional to the impacts of East Renton. The pro-rata share dollar amount to be paid shall be set by WSDOT, and documentation shall be provided by the East Renton applicant to the King County Land Use Services Division to show this payment has been made, prior to final plat recording. The pro-rata dollar amount to be paid shall be based on the following: o The final East Renton lot count o The trip distribution for East Renton o The total trips contributed to the intersection of SR 900.148 1h Ave by the plats of Aster Park (LOOP0024), Stone Ridge 9L99P3008), East Renton (L02P0005), Shamrock (L02POOl 4), Rosemonte (aka Ironwood -L03POO 18), Martin (L05POO 19) and any future land use applications submitted to King County for which compliance .{ ' I, --. :i L02P0005-Easl Renton 14 with the King County Intersection Standards (KCC 14.80) is required at either the SR 900/148'h Ave intersection, or the SR 900/164'h Ave High Accident Location. In Ihe event that either King County or WSDOT adopts a formal "latecomer's" system prior to final plat recording, that system may be followed in lieu of the approach described above, at the discretion of the applicant, as long as at a minimum there is a financial guarantee which assures the above-noted intersection improvements will be installed within two years of the date of recording of the plat of East Renton. [Comprehensive Plan Policy T-303 and King County Code 21 A.28.060A] (2.) Documentation ahall be provided to demonstrate to the satisfaction ofWSDOT that stopping sight distance (360 feet) is available on the cast leg of the SR 900/148" Ave intenoction. The interaoction shall be modified by the applicant, if necessary, so that this stopplns sight dhitanco requirement is met on the cast leg. In addition, the applicant shall clear vegetation within the right-of-way along SR 900, east of 148111 Ave., to maximize the entering sight distance for the north and south legs of the inteniection. (Comptehensive Plan Policy T-303 and King County Comprehensive Policy T -303 and King County Code 21A.28.060A] 2S. Toe recreation area may serve the adjacent plat of Rosemonte. If necessary, boundary line acljustmcnts may be approved to establish a portion of the East Renton plat recreation area as a part of the Rosernonte Plat, or the two plats may be m:orded as a single plat. 26. Wetland buffer averaging or additional buffer are required to compensate for reduction of wetland buffers adjacent to 145th A venue southeast, as proposed in the vicinity of the north property line, and to compensate for conatruction of the recreation tract trail through wetland bulfer between Tracts E and 0. ORDERED this 5th day of April, 2007. James N. O'Connor King County Hearing Examiner pro tem TRANSMI'ITED this 5th day of April, 2007, to the parties and interested persons of record: Robert L. Anderson P0Box3S3 Maple Valley WA 98038 Cam West Devel., Inc. Attn: Sara Slatten 9720 NE I 20th Pl. # I 00 Kirkland WA 98034 Kristine & Keith Childs 12004 • 148th Ave. SE Renton WA 98059 ~) ~ ! \ •. 'I '" ... -· L02P0005-East Renton 15 Claudia Donnelly Renee & Mark Engbaum Jolm Graves 10415. 147th Ave. SE 5424 NE I 0th St. Lozier Homes Renton WA 98059 Renton WA 98059-4386 1203 I 14th Ave. SE Bellevue WA 98004 Ralph Hickman Robert D. Johns Rebecca Lind 9720 NE I 20th Pl. # I 00 Jolms Monroe Mitsunaga City of Renton, EDNSP Kirkland WA 98034 1601 -I 14th Ave. SE,# 110 I 055 S. Grady Way Bellevue WA 98004 Renton WA 98057 Seattle KC Health Dept. Triad Associates Kim Clausaen E. Dist. Environ. Health 12112 -115th Ave NE DDES/LUSD 143SO SE Eastpte Way Kirkland WA 98034 MS OAK-DE-0100 Bellevue WA 98007 Lisa Dinsmore Peter Dye Nick Gillen DDES/LUSD DDES/LUSD DDES/LUSD MS OAK-DE--0100 MS OAK-DE-0100 MS OAK-DE-0100 Shirley Goll Kristen Langley Karen Scharer DDESILUSD DDES/LUSD DDES/LUSD MS OAK-DE-0100 MS OAK-DE-0100 MS OAK-DE-0100 Steve Towmend Larry West Kelly Whiting DDES/LUSD DDES/LUSD KC DOT, Rd. Srvcs. Div. MS OAK-DE-0100 MS OAK-DE-0100 MS KSC-TR-0231 Bruce Wbittalter DDIB8.ILUSD MS OAK-DE-0100 NQTICE QE &l!JHI TO APPEAL In order to appeal the decision of the Examiner, written notice of appeal must be filed with the Cleric of the King County Council with a fee of $250.00 (check payable to King County Office of Finance) on or bofon AprO 19, 2007. If a notice of appeal is filed, the original and six (6) copies of a written appeal statement specifying the basis for the appeal and argument in support of the appeal must be filed with the Clerk of the King County Council on or be/on April 26, 2007. Appeal statements may refer only to facts containod in the hearing record; new facts may not be presented on appeal. Filing requires actual delivery to the Office of the Clerk of the Council, Room I 025, King County Courthouse, 516 3111 Avenue, Seattle, Washington 98104, prior to the close of business (4:30 p.m.) on the date due. Prior mailing is not sufficient if actual receipt by the Clerk does not occur within the applicable time period. The Examiner does not have authority Io extend the time period unless the Office of the Clerk is not open on the specified closing date, in which event delivery prior to the close of business on the next business day is sufficient to meet the filing requirement. ~/ L02P0005-East Renton 16 If a written notice of appeal and filing fee are not filed within fourteen ( 14) calendar days of the date of this report, or if a written appeal statement and argument are not filed within twenty-one (21) calendar days of the date of this report, the decision of the hearing examiner contained herein shall be the final decision of King County without the need for further action by the Council. MINUTES OF THE MARCH 22, 2007, PUBLIC HEARING ON DEPARTMENT OF DEVELOPMENT AND ENVIRONMENTAL SERVICES FILE NO. L02P000S James N. O'Connor was the Hearing Examiner in this matter. Participating in the hearing were Karen Schan:r, Pete Dye and Kristen Langley, representing the Department; Robert Johns representing the Applicant; and Renee Bngbaum. Bxlu'bit No. I DOES file L02POOOS Exhibit No. 2 DOES preliminary report for L02P000S, prepared 12/29/2006 with attachments as follow: Exhibit No. 3 Exhibit No. 4 Exhibit No. 5 Exhibit No. 6 Exhibit No. 7 Exhibit No. 8 Exhibit No. 9 Exhibit No. 10 Exhibit No. II Exhibit No. 12 Exhibit No. 13 Exhibit No. 14 2.1. Plat Map w/66 Lot Plat Design 2.2. City of Renton Sewer Availability 23. Road Variance/L03V0049 2.4. Surface Water Management Varianco'L02V0089 2.5 Surface Water Management Varianco'L04V0103 2.6. Density Calculations w/R-4 wning 2. 7 Recreation crosa section for Tract G (previously labeled Tract C) Application for land use permit no. AO 1 P007 I received 413/2002 Enviro!Ullffllal checltlist received 4/3/2002 Revised SBPA Mitigated Determination ofNonsignilicancc, date of revised issuance: 12/29/2006 Affidavit of posting of Notice of Application indicating posting date of 5/3/2002, received by DOES on S/312002 Revised Site plan (66 lot preliminary plat map) received 3/17/2006 Aaaeaaor's maps (2) SE 10-23-0S & SW 11-23-0S Revised Level 1 Downstream Analysis by Triad & Associates, received 11/24/2004 Traffic Impact Analysis by Gary Struthen Associates received 4/3/2002 Request for School Information fonn from the Issaquah School District, received 4/2S/2002 King County Certificate of Water Availability, received 4/03/2002 Vicinity Map for L0SP0019, L03POOl 8 & L02P000S, prepared by KC staff on 3/19/2007 DOES Field Report and ors Infonnation dated 5/1/2002 Exhibit No. 15 Revised Wetlands Determination and Habitat analysis by C. Gary Schulz dated 9/12/2002 Exhibit No. 16 Wat~rtype/stream Classification Survey comments from Washington Trout, dated I 0/15/2004 ~/ L02P0005-East Renton 17 Exhibit No. 17 Exhibit No. 18 Exhibit No. 19 Exhibit No. 20 Exhibit No. 21 Exhibit No. 22 Exhibit No. 23 Exhibit No. 24 Exhibit No. 2S Exhibit No. 26 Exhibit No. 27 Exhibit No. 28 Exhibit No. 29 JNOC:g,,o L02P0005 RPT Drainage outfall report by Associated Earth Sciences, Inc., dated 9/24/2002 Boundary line adjustment proposal with attached map, dated 5/3/2004 Not entered Response to East Renton Transportation Comments by Gary Struthers Associates, Inc., dated 1/23/2003 Washington State Department ofTranportation cQmments regarding Traffic Impact Analysis, dated 11/13/2002 Letter from Claudia Donnelly dated 6/13/2003 regarding basin plan, with 2 attachments Note from Claudia Donnelly with attached copy of 11/12/03 newspaper article regarding transportation model City of Renton comments, regarding sewer service, dated 3/28/2002 Revised language for Condition 6 Conceptual recreation plan by Triad Aasociates Revised preliminary plat received March 22, 2007 Letter from Renee and Mark Engbaum dated March 22, 2007, with attached map indicating the location of their property Revisions to Conditions 20, 21 and 22 April I 0, 2007 OFFICE OF THE HEARING EXAMINER REPORT AND DECISION KING COUNTY, WASHINGTON 400 Yesler Way, Room 404 Seattle, Washington 98104 Telephone (206) 296-4660 Facsimile (206) 296-1654 Email: hearex@metrokc.gov SUBJECT: Department of Development and Environmental Services File No. LOJP0018 Proposed Ordinance no. 2007-0011 Location: Applicant: ROSEMONTE Preliminary Plat Application West of 148th Avenue Southeast at approximately Southeast I 17th Street, Renton Cam West Real Estate Dev., Inc. represented by Robert Johns, Attorney Johns Monroe Mitsunaga 1601 -I 14th Ave. SE,# 110 Bellevue, Washington 98004 Telephone: (425) 467-9960 Facsimile: ( 425) 451-2818 King County: Department of Development and Environmental Services (DDES) represented by Karen Scharer 900 Oakesdale A venue Southwest Renton, Washington 98055-1219 Telephone: (206) 296-7114 Facsimile: (206) 296-7051 SUMMARY OF RECOMMENDATIONS/DECISION: Department's Preliminary Recommendation: Department's Final Recommendation: Examiner's Decision: EXAMINER PROCEEDINGS: Approve subject to conditions Approve subject to conditions (modified) Approve subject to conditions (modified) Hearing Opened: March 22, 2007 Continued for Administrative Purposes: March 22, 2007 Hearing Closed: March 23, 2007 The public hearing on the proposed subdivision of Rosemonte was conducted concurrently with the L03POO 18-Rosemonte 2 The public hearing on the proposed subdivision of Rosemonte was conducted concurrently with the public hearing on the proposed subdivision of East Renton (ODES File No. L02P0005). Participants at the public hearing and the exhibits offered and entered are listed in the attached minutes. At 12:31 p.m. the hearing was continued for administrative purposes, to allow for the submission of proposed exh. no. 29, providing proposed text for modifications to the department's recommended conditions. Exhibit 29 was received by the Hearing Examiner on March 22, 2007, and the hearing was declared closed on March 23, 2007. A verbatim recording of the hearing is available in the office of the King County Hearing Examiner. ISSUES AND TOPICS ADDRESSED: • • • Recreation area Wetland buffers Surlilce water drainage SUMMARY: • • Red-tailed hawks nest Safe walking conditions 'The proposed subdivision of 9 .3 S acres into 2S lots in the urban area is approved subject to conditions. FINDINGS, CONCLUSIONS & DECISION: Having reviewed the record in this matter, the Examiner now makes and enters the following: (\j FINDINGS: .. _/ I • Geneml Informntioa: Developer: Engineer: STR: Location: Parcel: Zoning: Acreage: Number of Lots: Density: Lot Size: Proposed Use: Camwest Real Estate Development, Inc. 9720 NB 120° Plllce, Suite 100 Kirldand, WA 98034 COJltl:iCt: Sara Slatten 425-825-1955 Triad Asaociates 12112 I ls* Ave NB Klrldand, WA 98034 Contact: Gerry Buck 425-821-8448 10-23-05 West of 148 111 Ave SE and south of SEI 17111 St., if extended 1023059395 R-4 9.35 acres 25 Approximately 2.6 units per acre Approximately 5,300 square feet in size Single Family Detached Dwellings LOJPOO I &-Rosemonte Sewage Disposal: City of Renton Water District # 90 City of Renton 3 Water Supply: Fire District: School District: Issaquah School District Complete Application Date: July 8, 2003 2. Except as modified herein, the facts sot forth in the King County Land Use Services Division's preliminary report to the King County Hearing Examiner for the March 22, 2007, public hearing are found to be comet and are incorporated herein by this reference. The LUSD staff -enda approval of this subdivision, subject to conditions. 3. Dsvelopment of this subdivision may affect, and lead to the abandonment of, a red-tailed hawks neat on the adjacent property to the south (propoaod subdivision of Bast Renton). The red-trailed hawk is not an endangered or threatened species, and no protection of the red-tailed hawk Is afforded by law or the King County Code within the designated urban area of King County. 4. s. 6. The applicant has submitted a nwiaed recreation plan for this subdivision and the lllljacent plat of East Renton ( exh. no. 26). Thia plan would provide adequate area within Tract B, a trail acljacent to proposed lot 11, and within Tracts C, G and E and a proposed trail in the acljacent plat of East Renton, to serve these plats jointly with well conceived amenities for recreation and open space, coaais1i,ot with the n,quilements of the King County Code. To the extent that a portion of the recreatloo area necessary to meet the requirements for this plat is located on the Bast Renton Plat property, that variation &om KCC 21 A.14.180 can be corrected by boundary line adjustment or recording the two plats as a single plat, if DDES detennines that it is necessary to do so. Wetland buffers within this subdivision will need to be modified, utilizing tho buffer averaging provisions of the critical anlB8 code, to accommodate tho proposed alignment of 145th A venue Southeast in the vicinity of the south property line. The proposed subdivision will provide for safe wallcing conditions for students who will walk to Apollo Elementary School on southeast I 17th Street by constructing urban improvements to 141hb Avenue Southeast from the plat to Southeast I 17th Street. A school crosswalk (crossing 148th A venue Southeast) is located on the north side of Southeast I 17th Street, where an existing walkway is used by students to travel along the north side of Southeast I 17th Street, east from l 41hb Avenue Southeast to the sohool. This crosswalk also serves students walking from the 11191 north of Southeast I 17th Street. Consequently, the crosswalk should be maintained north of Southeast I 17th Street, unless it is physically Impractical to do so because of constraints resulting from the topography within the right-of-way for 148th Avenue Southeast, south of Southetst I 17th Street. If those constraints preclude extending curb, gutter and sidewalk from this plat to the north side of Southeast I 17th Street, the crosswalk can be relocated to the south, and improvements made on the east side of 148th Avenue Southeast extending north from the relocated crosswalk to Southeast I 17th Street. The conceptual review of drainage plans has shown that there are no downstream impacts likely to occur from development of the subject property if Level I flow control and basic water quality tresbnent improvements are designed and constructed in accordance with the 1998 King County 0 / ·, .... ~- L03POO 18-Rosemonte 4 Drainage Manual. The final drainage plan will include calculations to assure that the capacity of drainage facilities and discharge rates will be consistent with those flow control standards. CONCLUSIONS I. If approved subject to the conditions recommended below, the proposed subdivision will comply with the goals and objectives of the King County Comprehensive Plan, subdivision and zoning codes, and other official land use controls and policies of King County. 2. If approved subject to the conditions recommended below, this proposed subdivision will make appropriate provision for the public health, safety and general welfare, and for open spacea, dnilnage ways, streets, other public ways, transit stops, potable water supply, sanitary waste, pa,1111 and recreation, playgrounds, schools and school grounds and safe walking conditions for Sludents who only wallt to school; and it wlll serve the public use and interest. 3. The condldons for final plat approval recommended below are in the public interest and are nllSOIIBble and proportionate requirements necessary to mitigate the impacts of the development upon the environment 4. The dedications of land or easements within and adjacent to the proposed plat, BS required for final plat approval or BS shown on the proposed preliminary plat submitted by the Applicant on Mardi 31, 2006 and the conceptual recreation plan submitted March 22, 2007 (exh. 26), are nllSOIIBble and noceasary BS a direct result of the development of th is proposed plat, and are proportionate to the impacts of the development. S. No provisions are required to be made by this subdivision for the protection of the red-tailed hawks nest(s) on the site. 6. The proposed conceptual recreatlon plan submitted BS exh. no. 26 is a reasonable and appropriate plan to serve the plats of Bast Renton and Rosemonte jointly. Minor alterations may be made in the final design and review by DOES, and boundary adjustments, if necessary, may be made to comply with provisions ofKCC 2 IA.14.180-200. 7. Revlalons to the wetland buffen will be necessary to comply with the provisions of the King County Critical Areas Code, to pennit construction of 145th Avenue Southeast in the vicinity of the south property line. 8. In order to provide for safe walking conditions for students walking from this development to Apollo Elementary School, urban Improvements must be made to 148th Avenue Southeast north from the proposed plat to the north side of Southeast I 17th Street. These improvements should be made to the west side of 148th Avenue Southeast to the extent it is feasible to do so. In the event it is not practical to construct improvements extending to the existing crosswalk located at the north side of Southeast I 17th Street, a crosswalk may be established south of Southeast I 17th Street and a safe walkway provided on the east side of 148th A venue Southeast from the new crosswalk to the north side of Southeast I 17th Street. L03 POO 18-Rosemonte 5 9. Calculations for surface water detention facilities shall assure that the release of stonn water from the site does not exceed the rates allowed by the 1998 King County Drainage Manual for achieving Level I flow control. DECISION The proposed preliminary plat of Rosemonte as revised and revised and received on March 31, 2006 is approved, subject to the following conditions of final plat approval: I. Compliance with all platting provisions of Title 19A of the King County Code. A~I final recording of the plat of Rosemonte/L03POO 18 shall either occur subsequent to or concurrent with the recording of the Plat of East Renton/L02P000S. 2. All persons having an ownerahip interest in the subject property shall sign on the face of the final plat a dedication that includes the lan1JU831' set forth in King County Council Motion No. S952. 3. The plat shall comply with the bese density and minimum density requirements of the R-4 zone classification. All lots shall meet the minimum dimensional requirements of the R-4 zone classification or shall be as shown on tho face of the approved preliminary plat, whichever is larger, except that minor revisions to the plat which do not result in substantial changes may be approved at the discretion of the Department of Development and Environment Services. Any/all plat bounduy discrepancy(ies) shall be resolved to the satisfaction of ODES prior to the submiaal of the fioa1 plat documents. As used in this condition, "discropancy" is a boundary hiatus, an overlapping boundary or a physical appurtenance which indicates an encroaclunent, lines of possession or a conflict of title. 4. The applicant must obtain final approval from the King County Health Department. 5. All construction and upgrading of public and private roads shall be done in accordance with the King County Road Standards established and adopted by Ordinance No. I 1187, as amended (1993 KCRS). 6. The applicant must obtain the approval of the King County Fire Protection Engineer for the adequacy of the fire hydrant, water main, and fire flow standards of Chapter 17.08 of the King County Code. All future residences constructed within this subdivision are required to be sprinklered (NFPA l3D) unless the requirement is removed by the King County Fire Marshal or his/her deslgnee. The Fire Code requires all portions of the exterior walls of structures to be within I SO feet (as a person would walk via an approved route around the building) from a minimum 20-foot wide, unobstructed driving surface. To quality for removal of the sprinkler requirement, driving surfaces between curbs must be a minimum of28 feet in width when parking Is allowed on one side of the roadway, and at least 36 feet in width when parking is permitted on both sides. The road width requirement applies to both on-site access and roads accessing the subdivision. LOJ POO 18-Rosemonte Storm Drainage 6 7. Final plat approval shall require full compliance with the drainage provisions set forth in King County Code 9.04. Compliance may result in reducing the number and/or location of lots as sbown on the preliminary approved plat. Preliminary review has identified the following conditions of approval, which represent portions of the drainage requirements. All other applicable requirements in KCC 9.04 and the Surface Water Design Manual (SWDM) must also be satisfied during engineering and final review. a. b. C. d. e. f. Drainage plans and analysis shall comply with the 1998 King County Surface Water Design Manual. DOES approval of the drainage and roadway plans is required prior to any construction. Current standard plan notea and BSC notes, as oatabliabed by DDBS Engineering Review shall be shown oo the engineering plans. The following note shall be shown on tho final recorded plat: • All building downspoulB, footing drains, and draina from all impervious surfaces such as patios and driveways shall be connected to the permanent stonn drain outlet as shown on the approved construction drawinlls # oo file with DDBS and/or the Depar1ment of Transportation. Thia plan shall be submitted with the application of any building permit. All connections of the draina must be constructed and approved prior to the final building inspection approval. For those lots that are designated for individual lot infiltration systems, the systems shall be constructed at the time of the building pennit and shall comply with the plans on file." Stonn water facilities shall be designed using the KCRTS level one flow control standard. Water quality facilities shall also be provided using the basic water quality ~tioo menu. The sl7.e of the proposed drainage tracts may have to incr11UO to accommodate the required detention volumes and water quality facilities. All nmoff control facilities shall be located in a separate tract and dedicated to Kins County unless portions of the drainage tract are used for recreation space in accordance with KCC 21 A.14.180. The applicant has received approval for a drainage adjustment application regarding the proposed shared facility detention pond. The adjustment decision is contained within file number L04Y0103. During fmal review of tho onglneering plans, all applicable conditions of the adjustment approvals shall be satisfied. As stated in the drainage adjustment decision, the detention pond shall be designed using the Level I flow control standard and basic water quality standards are required for design of the drainage facility. lfa wet pond facility is provided for water quality, the design shall comply with the 3: I flow length ratio as outlined on page 6-72 in the dralnage manual. '( I \ ' .. L03POO 18-Rosemonte 7 g. As required by Special Requirement No. 2 in the drainage manual, the IOO-year floodplain boundaries for the onsite wetlands shall be shown on the final engineering plans and recorded plat. Access/Roads 8. The proposed subdivision shall comply with the 1993 King County Road Standards (KCRS) including the following requirements: a. During preliminary review tho applicant submitted a road variance application (Filo No. b. L06V0042), regarding the aag vertical cwvo and substandard stopping sight distance along the plat frontage. In response to tho variance application, tho King County Road Engineer provided a decision letter dated Juno 20, 2006 which approved tho varianco based upon reqund illumination for tho aag curve on 148111 Ave SB. Tho final road Improvements and design plans for tho project shall domollSlrate compliance with all applicable conditions of approval as stated in the variance decision. 148111 Avenue SB shall be improved along tho frontage as an urban collector arterial including all design criteria from the road variance decision. In accordance with KCRS 2.02, the curb location shall be desiped at 22-feet from the road crown to provide full width travel lanes and a bike lane. The preliminary design plan for Rosomonte shows road grading extending outside the right-of-way on the cast side of 1411"' A vo SB. During final engineering review, the applicant shall acquire euements for any propoaod construction on private property or provide an altomative design which is acceptable to King County for road construction within the existing right-of-way. If desired by the applicant, the road frontage improvements for Rosemonte may be satisfied by development of the East Renton plat. c. The proposed loop road within the subdivision (SB I I Bib St.) shall be improved as an urban subacceas street. d. Tract A shall be improved as a private joint use driveway serving a maximum of two lots. The serving lots shall have undivided ownership of the tract and be responsible for its maintenance. As specified in KCRS 3.0IC, improvements shall include an 18 foot paved surface and a minimum tract width of 20 foot. Drainage control shall include a curb or thickened edge on one side. e. Street trees shall be included in the design of all road improvements and shall comply with Section 5.03 of the KCRS. f. Street illumination shall be provided along the plat frontage for arterial streets in accordance with KCRS 5.05. g. The proposed road improvements shall address the requirements for road surfacing outlined In KCRS Chapter 4. As noted in section 4.0IF, full width pavement overlay is required where widening existing asphalt, unless otherwise allowed by King County. t<:.::/ (~ I L03POO 18-Rosemonte 8 h. 1481h Ave SE is classified an arterial street which may require designs for bus zones and tum outs. As specified in KCRS 2.16, the designer shall contact Metro and the local school district to determine specific requirements. i. Modifications to the above road conditions may be considered by King County pursuant to the variance procedures in KCRS 1.08. 9. All utilities within proposed rights-of-way must be included within a franchise approved by the King County Council prior to final plat recording. 10. The plat plan for Rosemonte sbows a retaining wall associated with 14Slb Ave SE which extends into the BSBL for the wetland buffer. During engineering review for East Renton, a revised road alignment and grading plan shall be provided which demonstrates that road construction within Rosomonte will comply with applicable sensitive area codes. The revised road design and grading plan may result in modification or loaa of lots as shown on the preliminary plat. Allllmalively, the applicant may aoek approval to use buffer averaging as a means to revise the location of the buffer and BSLB to achieve code compliance. 11. There shall bo no dim:! vehicular acc:esa to or from 148,. Ave SE from those lots which abut IL A note to this effect shall appear on the engineering plans and the final plat. 12. 13. Off-site access to tho subdivision shall be over a full-width, dedicated and improved road which has been accopted by King County for maintenance. If tho proposed accoss road has not been accepted by King County at the limo of recording. then said road shall bo fully bonded by tho applicant of this subdivision. Tho applicant shall provide a safe walking access to Apollo Elementary School with urban improvements along the west side of 1411° Ave NE to the existing crosawallt on the north side of SE 11 rt' St. This improvement includes urban frontage improvements along property frontage of tho Plat of East Renton, north of SE I 19th Street, as well as urban improvements along frontage of Roeemonte and urban improvements north to the existing crosswalk on tho north side of SE 11 '16 St. In the event it is not practical to construct urban improvements on the west side of 148th Avenue Southeast extending to the existing crosswalk, a new crosswalk may be established south of Southeast I 17th Street and a safe walkway provided on the east side of 148th A venue Southeast from the new crosswalk to the north side of Southeast I 17th Street. This alternative may use a graded surface on the east side of 148th Ave SE to ensure that school-age pedestrians are provided an acceptable-width walkway surface behind the curbing. The walkway shall be designed to the satisfaction of the school district and DOES. Mitigation/Impact Fees 14. The applicant or subsequent owner shall comply with King County Code 14.75, Mitigation Payment System (MPS), by paying the required MPS fee and administration fee as detennined by the applicable fee ordinance. The applicant has the option to either: (I) pay the MPS fee at the final plat recording, or (2) pay the MPS fee at the time of building pennit issuance. If the first ~' ., ' L03POO I &-Rosemonte 9 option is chosen, the fee paid shall be the fee in effect at the time of plat application and a note shall be placed on the face o'fthe plat that reads, "All fees required by King County Code 14.75, Mitigation Payment System (MPS), have been paid." If the second option is chosen, the fee paid shall be the amount in effect as of the date of building pennit application. 15. Lots within this subdivision are subject to King County Code 21A.43, which imposes impact fees to fund school system improvements needed to serve new development. As a condition of final approval, fifty percent ( 50%) of the impact foes due for the plat shall be assessed and collected immediately prior to the recording, using the foe schedules in effect when the plat receives final approval. The balance of the assessed foe shall be allocated evenly to the dwelling units in the plat and shall be collected prior to building pennit isauance. WetlancDs 16. Preliminary plat review has identified specific requirements which apply to this project as listed below. All other applicable requirements from K.C.C. 21A.24 shall also be addressed by the applicant a. b. C. The Class 2 wetland shall have a minimum SO-foot buffer of undisturbed vegetation as measured from the wetland edge. Sensitive area tract(s) shall be used to delineate and prom:t Bell8itive areas and buffers in development proposals for subdivisions and shall be recorded on all documents of title of record for all affected lots. Buffer width averaging may be allowed by King County if it will provide additional protection to the wetland/stream or enhance there functions, as loog as the total area contained in the buffer on the development propoaal site does not dec,ease. In no area shall the buffer be less than 65 percent of the required minimum distance. To enS\ffll such functions are enhanced a mitigation plan will be required for the remaining on-site sensitive areas. An enhancement plan shall be submitted for review during engineering review. d. A I 5-foot BSBL shall be established from the edge of buffer and/or the sensitive areas Tracl(s) and shown on all affected lots. e. To ensure long tenn protection of the Sensitive Areas a split-railed fence ofno more than 4 feet in height shall be installed along the Sensitive Area Tract boundaries in the area of proposed lots. Sensitive Area signs shall be attached to the fence at no less than I 00 foot intervals. f. If alterations of streams and/or wetlands are approved in conformance with K.C.C. 21A.24, then a detailed plan to mitigate for impacts from that alteration will be required to be reviewed and approved along with the plat engineering plans. A performance bond or other financial guarantee will be required at the time of plan approval to guarantee that the mitigation measures are installed according to the plan. Once the mitigation work is completed to a ODES Senior Ecologist's satisfaction, the performance bond may be replaced by a maintenance bond for the remainder of the five-year monitoring period L03 POO 18-Rosemonte to guarantee the success of the mitigation. The applicant shall be responsible for the installation, maintenance and monitoring of any approved mitigation. The mitigation plan must be installed prior to final inspection of the plat. 10 g. Prior to commencing construction activities on the site, the applicant shall temporarily mark sensitive areas tract(s) in a highly visible manner, and these areas must remain so marked until all development proposal activities in the vicinity of the sensitive areas are completed. h. During engineering plat review the applicant shall provide a wetland hydrology analysis to demonstrate bow the wetland hydrology will be maintained poat-oonstruction. i. Detention out-fall strul:tures maybe permitted within the wetland/stream buffers, however, SU'Uctures shall be located in the outer edge of the buffer, if possible. All buffer impactS shall be mitigated. 17. Development authorized by this approval may require other state and/or federal permits or approvals. It is the applicant's responsibility to correspond with these agancies prior to beginning work on the site .. 18. During engineering review, the plan set shall be routed to the sensitive areas g,oup to determine if the above conditions have been met. Geotecbmical 19. The applicant shall delineate all on-site erosion hazard areas on the final engineering plans (erosion hazard areas are defined In KCC 21A.06.41S). The delineation of such areas shall be approved by a DOES geologist. The requiremenlB found In KCC 2 IA.24.220 concernlng erosion hazard areas shall be met, including seasonal restrictions on clearing and grading activities. 20. The geotechnical work for this project shall be accomplished In accordance with recommendations presented in the geotechnical engineering report dated April 23, 2003 by Associated Earth Sciences, Inc. a. Structural fill placement shall be continuously monitored and approved in writing by the project geotechnical engineer or engineering geologist. b. After excavation and prior to structural fill or foundation placement, all bearing soils shall be inspected and approved in writing by an experienced geotechnical engineer or engineering geologist. c. Structural fill placed for improved areas such as pavements or floor slabs shall be compacted to at least 95 percent of the maximum dry density by ASTM test designation D-i 557 (Modified Proctor) or as recommended by the project geotechnical engineer or engineering geologist. d. All pile foundation installations shall be continuously monitored by a registered geotechnical engineer or a licensed engineering geologist for compliance with an '{ ' ·, , __ LOJPOO 18-Rosemonte 11 approved plan and the geotechnical report. Compliance and approval of the pile foundation installation shall be documented in a report to the King County site or building inspector. e. The location and height of any proposed rockeries or retaining walls shall be shown on the engineering plans. \ f. Any created till slope that is 40 percent or steeper and IO feet or grgter in vertical height shall be subject to a SO-foot wido buffer plus a IS-foot wide setbaek area from its top, too and sidos. This buffer may be reduced to 10 feet with a satisfalltory evaluation by a registored geotechnical engineer or licensod engineorlng geologist. g. The applicant shall delineate all on-site erosion hazard areas on tho final ongineering plans (erosion hazard llN88 are defined in KCC 21A.06.41S). The delineation of such areaa shall be approved by a ODES geologist. The requirements found in KCC 21 A.24.220 concerning eroaion hazard areas shall be met, Including seasonal restrictions on clearing and grading activities. Sensitive Ann 21. The following note shall be shown on the fmal engineering plan and recorded plat: RESTRICTIONS FOR SENSITIVE AREA TRACTS AND SENSITIVE AREAS AND BUFPBRS Dedication of a sensitivo area tract/sensitive area and buffer conveys to the public a beneficial interest in the land within the tract/sensitive area and buffer. Thia Interest Includes the preservation of native vegetation for all purposes that benefit the public health, aofety and welf&R, including control of surface water and erosion, maintenance of slope atnblllty, and protection of plant and animal baliitat. The sensitive area tract/sensitive area and buffer Imposes upon all present and future owners and occupiers of the land subject to the tractl88Dllitlve area and buffer the obligation, enforceable on behalf of the public by King County, to leave undisturbed all trees and othor vogetation within the tract/sensitive area and buffer. The vegetation within the tract/sensitive area and buffer may not be cut, pruned, covered by fill, removed or damaged without approval in writing from the King County Department of Development and Environmental Services or Its successor agency, unloss otherwise provided by law. The common boundary between the tract/sensitive area and buffer and the area of development activity must be marked or otherwise flagged to the satisfaction of King County prior to any clearing, grading, building construction or other development activity on a lot subject to the sensitive area tract/sensitive area and buffer. The required marking or flagging shall remain in place until all development proposal activities in the vicinity of the sensitive area are completed. No building foundations are allowed beyond the required 15-foot building setback line, unless otherwise provided by law. r( \~- L03POO 18-Rosemonte Recreational Area 12 22. The plat design shall be revised to provide the minimum suitable recreation space consistent with the requirements ofK.C.C. 21A.14.180 and K.C.C. 21A. 14.190 (i.e., minimum area, as well as, sport court(s], children's play equipment, picnic tsble(s], benches, etc.), as shown on hearing exh. no.26. Other 23. 24. a. A detailed recreation space plan (i.e., location, area calculations, dimensions, landscape specs, equipment specs, etc.) shall be submitted for review and approval by DDBS prior to or concurrent with the submittal of engineering plats. b. A perfonnance bond for recreation space Improvements shall be posted prior to recording of the plaL c. Modify the plat, as needed to comply with KCC 21A.14.180.F, as shown in hearing oxh. no. 26 for the plat of East Renton (DDBS File No. L02P000S). A homeowners' association or other workable organization shall be established to the satisfaction ofDDES which provides for the ownership and continued maintenance of tho recreation, open space and/or sensitive area lract(s), which combine usage of the recreation area of the plat of Bast Renton (DDBS File No. L02POOOS) and this plat, as shown in hearing exh. no. 26 for tho plat of East Renton. Sueet trees shall be provided as follows (per KCRS 5.03 and K.C.C. 2 IA.16.050): a. Trees shall be planted at a rate of one \tee for every 40 feet of frontage along all roads. Spacing may be modified to accommodate sight distance requirements for driveways and intonections. b. Trees shall be located within tho street right-of-way and plantod in accordance with Drawing No. S-009 of the 1993 King County Road Standards, unless King County Department of Transportation determines that trees should not be located In the street right-of-way. c. If King County detennines that the required street trees should not be located within the right-of-way, they shall be located no more than 20 feet from the sueet right-of-way line. d. The trees shall be owned and maintained by the abutting lot owners or the homeowners association or other workable organization unless the county has adopted a maintenance program. Ownership and maintenance shall be noted on the face of the final recorded plat. e. The species of trees shall be approved by DOES if located within the right-of-way, and shall not include poplar, cottonwood, soft maples, gum, any fruit-bearing trees, or any other tree or shrub whose roots are likely to obstruct sanitary or storm sewers, or that is not compatible with overhead utility lines. L03POO 18-Rosemonte 13 f. g. h. i. The applicant shall submit a street tree plan and bond quantity sheet for review and approval by DOES prior to engineering plan approval. The applicant shall contact Metro Service Planning at (206) 684-1622 to determine if 14811, Ave SE is on a bus route. If 1481b Ave SE is a bus route, the street tree plan shall also be reviewed by Metro. The street trees must be installed and inspected, or a perfonnance bond posted prior to recording of the plat If a perfonnance bond is posted, the street trees must be installed and inspected within one year of recording of the plat At 1he time of inspection, if the trees are found to be installed per the approved plan, a maintenance bond must be submitted or the performance bond replaced with a maintenance bond, and hold for one year. After one year, the mslntenance bond may be releaaed after DDBS baa completed a second inapectlon and determined that the trees have been kept healthy and thriving. A landacape inspection fee shall also be submitted prior to plat recording. The inspection fee is subject to change based on the cummt county fees. 2S. The engineering plans for this project shall Identify the location of any wells on the site and provide notes which address the requirements for the con~ to abandon the well(s) pursuant to requirements oudined in the Washington Administrative Code (WAC 173-160). (( / SEPA 26. The following have been established by SEPA as necessary requirements to mitigate tho adverse environmental impacts of this development. The applicants shall demonstrale compliance with those items prior to final approval. (I.) To mitigate tho significant adverse impact the plat of Rosemonte will have on tbe intersections of SR 900/148"' Ave SE and SR 900/164"' Ave SE, tbe applicant shall install, either individually or in coqjunction with other development projects in this area, the following improvements at the SR 900/148"' Ave intersection: o A traffic signal, and o Eastbound and westbound left tum lanes The design for the SR 900/148 111 Ave intersection improvements shall be approved by the Washington State Department of Transportation (and by King County to the extent such improvements are located in County right-of-way). In addition, at a minimum, the existing entering sight distance looking east for the north and south legs of the intersection (602 feet and 386 feet, respectively) shall not be reduced as part of the intersection improvements. Documentation shall be submitted to show this requirement Is met. All construction work associated with the intersection improvements shall be completed between April I" and September 301h. This seasonal restriction shall be clearly shown on the final engineering plans. In lieu of the installation of the above-noted intersection improvements prior to final plat approval, the applicant may post a financial guarantee with WSDOT which assures the installation of these improvements within two years of the recording ofRosemonte. In this ~) LOJPOO I S-Rosemonte 14 event, intersection improvement design must be approved by WSDOT prior to King County approval of the engineering plans for Rosemonte. If the above-noted intersection improvements have already been made by others prior to the recording of Rosemonte, or a financial guarantee has been posted by others which assures the installation of these improvements, then the applicant for Rosemonte shall pay a pro-rata share dollar amount to the developer who has made the improvements or "bonded" for the improvements, in an amount proportional to tho impacts ofRosemonte. Tho pro-rata share dollar amount to be paid shall be sot by WSDOT, and documentation shall be provided by the Roaemonte applicant to tho King County Land Use Services Division to show this payment has been made, prior to final plat n,cording. Tho pro-rata dollar amount to be paid shall be based on the following: o The final Rosemonte lot count o The trip distribution for Ro.emonle o Tho total trips contributed to tho interseetlon of SR 900.J4gd' Ave by tho plats of Aster Park (LOOP0024). Stone Ridge 9L99P3008). Bast Rllllton {L02P0005). Shamrock (L02POO 14). Roaomon1e (aka Ironwood -L03POO 18). Martin (LOSPOO 19) and any future land use appllcaticns submitted to King County for which compliance with tho Kini County lntenlection Standards (KCC 14.80) Is required at either the SR 900/148 Ave intenectlon, or the SR 900/1646 Ave High Accident Location. In the event that either King County or WSDOT adopts a formal "la18C:Omer's" system prior to fmal plat recording. that system may be followod in lieu of the approadl described above, at the discretion of the applicant, as long as at a minimum there is a financial guarantee which assures the above-noted intersection improvements will be installed within two years of the date of recording of the plat ofRosemonto. (Comprehensive Plan Policy T-303 and King County Code 21A.28.060A] (2.) Documentation shall be provided to demonslratll to the setiafaotion of WSDOT that stopping sight distance (360 feet) is available on the east leg of the SR 900/1411 6 Ave intersection. The interseetlon shall be modified by the applicant, If necessary, so that this stopping sight distance requirement is met on the east leg. In addition, the applicant shall clear vegetation within the right-of-way along SR 900, east of 1411° Ave., to maximize the entering sight distance for the north and south legs of the intersection. [Comprehensive Plan Policy T-303 and King County Comprehensive Policy T-303 and King County Code 21A.28.060A) ORDERED this 10th day of April, 2007. James N. O'Connor King County Hearing Examiner pro tem (C_j { L03 POO 18-Rosemonte 15 TRANSMITIED this 9th day of April, 2007, to the parties and interested persons of record: Robert L. Anderson Cam West Devel., Inc. Kristine & Keith Childs PO Box 353 Attn: Sara Slatten 12004 -148th Ave. SE Maple Valley WA 98038 9720 NE 120th Pl. #100 Renton WA 98059 Kirkland WA 98034 Claudia DoMelly Renee & Mark Engbaum John Graves 1041S -147th Ave. SE 5424NE 10th St Lozier Homes Renton WA 98059 Renton WA 98059-4386 1203 114th Ave. SE Bellevue WA 98004 Ralph Hickman Robert D. Johna Rebecca Lind 9nONB 120th Pl. #100 Johns MOlll'Oll Mltaunaga City of Renton, EDNSP Kirkland WA 98034 1601 -114th Ave. SE,# 110 IOSS S. Grady Way Bellevue WA 98004 Renton WA 980S7 Seattle KC Health Dept. Triad Associates Kim Claussen E. Dist. Environ. Health 12112 • 11Sth Ave NE DDESILUSD 143SO SE &stgate Way Kirldand WA 98034 MS OAK-DE-CHOO Bellevue WA 98007 Lisa Dinsmore Peter Dye Nick011len DDES/LUSD DDESILUSD DDES/LUSD MS OAK-D&-0100 MS OAK-DE-0100 MS OAK-DE-0100 Shirley Goll Kristen Langley Karen Scharer DDES/LUSD DDESILUSD DDESILUSD MS OAK-D&-0100 MS OAK-DE-0100 MS OAK-DE-0100 Steve Townsend Larry West Kelly Whiting DDES/LUSD DDES/LUSD KC DOT, Rd. Srvcs. Div. MS OAK-DE-0 I 00 MS OAK-DE-0100 MS KSC· TR-6231 Bruce Whittaker DDES/LUSD MS OAK-DE-0100 NOTIQJ;,; QE RIGHI IQ Aefll.Y. In order to appeal the decision of the Examiner, written notice of appeal must be filed with the Clerk of the King County Council with a fee of $2SO.OO (check payable to King County Office of Finance) on or before April 24, 2007. Ifa notice ofappeal is flied, the original and six (6) copies ofa written appeal statement specifying the basis for the appeal and argument In support of the appeal must be filed with the Clerk of the King County_ Council on or before May 1, 2007. Appeal statements may refer only to facts contained in the hearing record; new facts may not be presented on appeal. Filing requires actual delivery to the Office of the Clerk of the Council, Room I 02S, King County Courthouse, 516 3rd Avenue, Seattle, Washington 98104, prior to the close of business (4:30 p.m.) on the date due. Prior mailing is not sufficient if actual receipt by the Clerk does not occur within the ~/ LOJPOOIS-Rosemonte 17 ( Exhibit No. 15 Exhibit No. 16 Exhibit No. 17 Exhibit No. 18 Exhibit No. 19 Exhibit No. 20 Exhibit No. 21 Exhibit No. 22 Exhibit No. 23 Exhibit No. 24 Exhibit No. 25 Exhibit No. 26 Exhibit No. 27 Exhibit No. 28 Revised Wetlands Determination and Habitat analysis by C. Gary Schulz dated 9/12/2002 Watertype/stream Classification Survey comments from Washington Trout, dated 10/1 S/2004 Drainage outfall report by Associated Earth Sciences, Inc., dated 9/24/2002 Boundary line adjustment proposal with attached map, dated S/3/2004 Not entered Response to East Renton Transportation Comments by Gary Struthers Associates, Inc., dated 1/23/2003 Washington State Department ofTranportation comments regarding Traffic impact Analysis, dated l l/l 3/200Z Letter ftom Claudia DoMelly dated 6113/2003 regarding basin plan, with 2 attachments Note ftom Claudia DoMelly with attached copy of 11/12/03 newspaper article regarding transportation model City of Renton comments, regarding sewer service, dated 3/28/2002 Revised language for Condition 6 Conceptual recreation plan by Triad Associates Revised preliminary plat received March 22, 2007 Letter ftom Renee and Marlt llnghamn dated March 22, 2007, with attached map indicating the location of their property Exhibit No. 29 Revisions to Conditions 20, 21 and 22 JNOC:gao L03POOl8 RPT @ ( King County Department of Development and Environmental Services 900 Oakesdale Avenue SW Renton, WA 98055-1219 copy ( ( March 24, 2005 Sara Slatten Cam West Development 9720 NE 120th Place # I 00 Kirkland, WA 98034 Rebecca S. Cushman, P.E. Triad Associates I 1814-115lh Avenue NE Kirkland, WA 98034 RE: East Renton Subdivision 1998 KCSWDM Shared Facility Plan: DDES Project File No. L02P0005 and Adjustment File No. L04VOl03 Dear Applicant and Engineer: The Land Use Services Division, Engineering Review Section, has completed review of the Shared Facility Plan request for the East Renton and adjoining Rosemonte subdivisions. This request addresses the 1998 King County Surface Water Design Manual (KCSWDM), Special Condition No. I, Section 1.3.1, Other Adopted Area-Specific Requirements and the Shared Facility Plan Guidelines published in a memo dated September 15, 1999 describing the Shared Facility Plan approval process. Our review of the preliminary plat plans provides the following findings: I. The East Renton subdivision is located on the east side of 148th Avenue SE at approximately SE 120th Street. The 66 lot, 19.6 acre, East Renton subdivision is undergoing preliminary review under LUSD file n\lffiber L02P0005. The East Renton subdivision had previously processed 1998 KCSWDM adjustment L02V0089 for a diversion to consolidate subbasin flows into a single, on-site facility. 2. The proposed Rosemonte subdivision is located adjacent to East Renton along the north property line. The 41 lot, 14.7 acre Rosemonte subdivision is also undergoing preliminary approval under LUSD file number L03P0018. At this time, Cam West (developer of East Renton) is in negotiation to purchase the eastern portion of Rosemonte. The developer ofRosemonte is also in negotiation with the City of Renton to annex the western portion of Rosemonte into the city. 3. The East Renton and Rosemonte subdivisions are located in the Honey Creek subbasin of the May Creek basin. Both sites are subJect to the Level One flow control and Basic water'quality requirements of the 1998 KCSWDM. 4. The proposal is to officially acknowledge the accommodation of the northeast portion of the East Renton subdivision that is naturally tributary to the north property line into ( \ ( East Renton/L02P0005 and Rosemonte/L03P00! 8 March 24, 2005 Page 2 of3 the shared facility design of the Rosemonte subdivision. This approach would abandon the diversion adjustment (L02V0089) previously processed that would have diverted flows from this area into the East Renton 's on-site drainage facility. 5. If Cam West purchases the eastern portion of Rosemonte, as previously indicated, then . these two projects could be designed and reviewed concurrently. Construction could then either occur concurrently or in phases with the understanding that the shared drainage facility would be constructed before the development of the two contributing portions of each site. If the two projects remain with separate applicants, the shared · drainage facility in the Rosemonte subdivision would still need to be constructed first to its final configuration. 6. A consolidation of facilities for the proposed subdivisions will be more economical in long term maintenance. Based on these findings, we hereby approve this request for a shared drainage facility with shared facility plan for the East Renton and Rosemonte subdivisions with the following conditions: I. The developer of the shared drainage facility is responsible for any cost sharing agreements that may need to be set up as part of the implementation of the shared facility plan. 2. Engineering plans for both the East Renton and Rosemonte subdivisions shall note this approved shared facility plan. 3. If the two projects are phased separately in time, the shared drainage facility must be constructed first and operational before any lots tributary to the facility can be recorded. 4. If there is a change of design standards or project design that requires modification of the shared facility design, an update to the shared facility plan shall be provided as part of the trailing project's engineering review submittal. If you have any further questions regarding this KCSWDM Shared Facility Plan approval or its conditions, please contact Mark Bergam at (206) 296-7270. Sincerely, James Sanders, P.E. Development Engineer Engineering Review Section Land Use Services Division · Jim Chan, P.E. Supervising Engineer Site Engineering and Planning Section Building Services Division ( J ( ( East Renton/L02P0005 and Rosemonte/L03POOl 8 March 24, 2005 Page 3 of3 cc: Curt Crawford, P.E., Supervising Engineer, Stonnwater Services, KCDNR Pete Dye, P.E., Engineer III, Engineering Review Section, LUSD Kim Claussen, Project/Program Manager Ill, Current Planning Section, LUSD Mark Bergam, P.E., Engineer III, Engineering Review Section, LUSD ( ( King County Department of Development and Environmental Services 900 Oakesdale Avenue Southwest Renton, Washington 98055·1219 Surface Water Design Manual Requirements/ Standards Adjustment* Request Project Name: ODES Projelll Fll'lfl9ll~' · ft) l O O ODES Eng!W1'JI!, e: -· e.Jl East Renton Peter Dye, Kim.Claussen K.C. Design Engineer: Project Address: 12013-149th Ave SE Renton, WA 99059. Rebecca S, Cushman AppllcanUAgenl: Phone: CamWeet Development 425-825-1955 Signature: Triad Associates Phone: Ad<lress: City, Stal<!, Zip e: 9720 NE 120th PL #100 KirlHand, 9903 Address: City, Slate, Zip Code: 11914 '115th Av~ NE kirkland O 4 INSTRUCTIONS TO APPLICANT/DESIGN ENGINEER: Please be sure to lndude aU plans CT .I.R., If available), sketches. photos and maps thal may asslsl In complete review and consideration of this adjustment request Failure lo provide an pertinent lnformatioo may result In delayed processing or denial of you, request. Please submit two oomolete COQtAA of this reauest aooHcatlon form and aooltcable fee to the DOES Intake Counter, at 900 Oakesdale Avenue Soulhwes~ Renton, Washington 98055-1219. For additlonal lnformattoo, phooe Randall Parsons, P.E., at (206) 296-7207. llBP'BR TO SBCTION 1. 4 IN CBAPTBR 1 OP TBB StJRPACB WATBR DBSIGH MANUAL FOR AI>JUSTMBNT:9 DESCRIPTION OF ADJUSTMENT REQUEST: c!l Standard D Complex D Experimental D Blanket a Pre-application Core Requirement #3 & Special Requirement #1 -Offsite shared facility. APPLICABLE VERSION KCSWDM: D 1990 (11/95)' GI 1998 (9/98) o.c-:--=-- • (Note: the term "variance· replaced by "adjustmenr) APPLICABLE SECTION(S) OF STANDARDS: 1998 KCSWDM 1.2.1 Core Requirement #3; Special Requirement #1 JUSTIFICATION PER KCSWDM SECTION 1.4.2 l.l See attachments listed below. Adjustment letter, Level 1 Downstream Analysis, Drainage Report for Ironwood (Qosemonte). AUTHORIZATION SIGNATURES: DETERMINATION: 0 Approval )( Cond/Uonal Approval (see below) Preliminary Plat Map, Preliminary D Denial o DNR/WLRD Approval Signed: --UI--J'f-:.,.,.-,jr--Date: ----- DOES Staff RecommendaUon Signed: Date: Condition• ol Approval: See attached Memo Dated: ODES, Bldg. Serv. Div., Site Engineering & Planning Supervisor: Signe · l,,tl~-71!:~~--- D F9 9/ ERS/ S\.IDM· ADJ. doc <'<>O:l<'l><>Jc,y ...... " __ •• ~~ ... __ ,· ( November 15, 2004 MarkBergam King County ODES 900 Oakesdale Ave MS LB Renton, WA 98055-1219 RE: East Renton KC Project# L02P0005 Triad Job No. 01-047 Dear Mark: 11814 IISthAvenueNE Kirkl<md. WA 98034-6923 4ZS.8Zl.8448 425.821.3481 fax 800.488.0750 toll free www.lriadassoc.com This request is to approve the following adjustments to the 1998 King County Surface Water Design Manual. 1. Adjustment to Core Requirement #3 -Allow stormwater quantity and water quality treatment controls to be provided in an offsite facility. 2. Adjustment to Special Requirement #1 -Allow the utilization of the offsite facility as a shared facility within the Preliminary Plat ofRosemonte, King County File No. L03P0018. To assist in the review of the adjustment request, please see the enclosed project description, Level I Downstream Analysis and the Preliminary Plat Map submittal for East Renton. In addition, copies of the Preliminary Storm Drainage Calculations for Rosemonte plat (Formerly known as Ironwood) are included. Project overview: The East Renton project proposes to create 66 single-family lots on a 19.6 acre property. 15.92 acres will be developed, with the remainder left as protected wetlands and associated buffers together with a future development tract with assigned density not to exceed two single-family lots. The site is west of 148th AVE. SE, north of SE 124th Street and south of SR 900 in King County, Washington. Two detention/water quality facilities are proposed; one located in the northwest comer of the site referred to as the East Renton Vault, and the other, located at the north east comer of the preliminary plat ofRosemonte (King County Project No. L03P0018), referred to as the Rosemonte Pond. ( I ( Page 2 MarkBergam King County ODES Nove.mber 15, 2004 Adjustment Discussion: The request for adjustment is to provide an offsite-shared facility utilizing the Rosemonte Pond. Core Requirement #3 states that all proposed projects must provide onsite flow control facilities to mitigate the impacts of increased storm and surface water runoff generated by the addition of new impervious surface and any related land cover conversion. Special Requirement #1 states that shared facility drainage plans shall be approved by King County to allow two or more projects to share drainage facilities required by this manual. In addition to serving Rosemonte, the shared facility will serve that portion of the East Renton project that currently sheetflows across its north property line onto Rosemonte. The Applicant for East Renton previously applied for and obtained an adjustment for diversion away from this parcel for the same tributary area (Activity No. L02V0089). Approval of this adjustment request will eliminate the need for a diversion. The assumed land cover for the design of the pond has been calculated based on maximum zoning impervious coverage and utilization ofa Level I Detention Standard. Water quality will be provided using a basic wetpond design. Benefits to the public are as follows: o Maintenance costs for a single facility are lower than maintaining two facilities. o In addition to savings in pond maintenance, the conveyance system maintenance will be streamlined since less pipe with appurtenances will be required. Please review and approve our request for a drainage adjustment. If you require any further information for your consideration, please give me a call. Sincerely, TES ebecca S. ushman, P.E. Project Engineer ; I ----~ \ I ; I I., ,OS -·-·-... , u •/ ~ f i I ·---·1···-··--.. 1·--·········-·-"1:1:: ·1 \ ·1 _J ,\!I' '--~-""" \ ~ J t ' I I ~ ~ \~ '. ';\i! i / ~---.... J\) .. • -.:. .. • ,(.} t . "S ',(> I ' ; • \ 0). ". o:i ·~(() ·woti· !! \;1: -· --1-,, ',,-1_, __ l_,_ .. \c1 I l~I /// I\ ( +. ', .. , k:. '.go,-~-. 'cf7 \ ·r-~\ ' \ I I ! :-e.,: I ', \ ' ' \ \ ! ·1 \1 -• • -i • -• ~ • • . • -1 , ; . ~ I \ .,..., \ \ i \ \ '1 \ \\ \ ·,\ c;;?·,=, ·, \• \i· ill\'.~ ~ '\ ... J t1\\\\'. ~~ \ "-> \ '' ; \ \ -\ \ \ \li;::::>· ~ ' ~\ ' 1\5 •. ~ · ; \ \ \ I :r. I ' I \ I r, 1 • ,. ; , ·, \ , \ ($IJ8ACC£S$)\ , \ \ \ \ \,' 1147 A VE S · '. \ \ , ..... ,, ·-------- i ' l ' . --.. . ' ~-" l -•. '-,---------. . ···-·--' , I ' ·, ----=-.:z____ -~------. ,,-. ', ·-~--.. , ' I \ \ \ \ --- ,, ( ct220408:lla Chris Bicket 360 668 1133 { I ·.:;·~':;-, : .r.-,!\J.:l'.,\\ ··::·;Jt; KlngCounty Road Services Division Dcpsrimml of'Transpor1atlon 201 SouthJacbon Street Scalllc, VIA 9Ut04-385'G October 20, 2004 CamW est Development C/0 Chris Bicket, P.E. P.O. Box 65254 Seattle, WA 9815 5 RE: Road Variance L03V0049 -East Renton Property Plat -Related Fi!e L02P0005 Dear Sir/Madam: Thank you for submitting your application for a road variance from the King County Road Standards (KCRS). You requested a variance from Section 2.12 of the KCRS concerning the stopping sight distance (SSD) along the plat frontage on 1481h Avenue SE. 148th Avenue SE is a collector arterial with posted speed limit of35 MPH. The original proposal to match the curb and sidewalk section to the existing vertical alignment has been revised to a 620-foot vertical crest curve that will lower the alignment by up to 3.5 feet and improve SSD. The revised design will utilize the two-foot target criteria in the American Association of State Highway and Tmnsportation Official's (AASHTO) manual. The proposal will provide 455 feet ofSSD along the crest curve that will meet KCRS with a downgrade correction for the average 6% grade. I approve a variance to allow the 620-1.bot vertical curve with 455 feet ofSSD, utilizing a two-foot target. The slight grade break (under 1%) at the north end of the vertical curve is also acceptable. No variance is required for the vertical crest curve 400 feet to the west of the site because the SSD meets KCRS approaching the west property line. A copy of the staff's analysis, findings and conclusions is enclosed. If you have any questions, please call Craig Comfort, Road Variance Engineer, Traffic Engineering Section, at 205-263-6] 09. ~erely ~ '"\ "-· "#f"i/1:6::,/U~~ Paulette Norman, P.E. County Road Engineer PN:CC:kc p.2 ( ct 22 04 08:lla Chris Bicket 360 668 1133 p.3 ( I \ ® KlnrCouniY ---l>msion Department o!Traosport.at.ion Tracr.11 En(Pneering Section MS KBC-TR·Clll:12 201 SoulhJ..i..on SLTHt Seattle, WA 98L04 October 20, 2004 TO: Variance File FM: Craig Comfort, P.E., Road Variance Engineer, Traffic Engineering Section RE: Road Variance L03 V0049 -!3•'1! Renton Pmperty Plitt -Related File L02P000S Applicant's Presentation: l. The proposed 66-lot plat is on the west side of 148th Avenue SE at SE 12olh Street. 148th Avenue SE is a collector arterial with a 35 MPH posted speed limit. The existing vertical alignment along the plat frontage is a long crest vertical curve that extends for hundreds of feet beyond the site in both directions. The crest curve has more severe curvature changes . beyond the site frontage that restrict the stopping sight distance (SSD) sightlines. 2. King County Department of Transportation (KCDOT) staff made a decision subsequent to a pre-design meeting on 4/19/01, and a memo dated 8/8/01, that the developer, CamWest would not be required to reconstruct 148 ... Avenue SE, and a variance would not be required. The decision was not in writing and the County subsequently changed their position and requests a road variance to leave the vertical alignment and be allowed to match to the alignment with the curb and sidewalk improvements. The applicant's opinion is that this variance is unnecessary because the SSD deficiency is pre-existing and unrelated to impacts of the proposed plat. The cost of installing frontage and offsite improvements to correct the condition is unreasonably high and unrelated to impacts of the East Renton Property Plat. The proposed plat did not create, or will not exacerbate the SSD condition on its frontage. Changing the grade of 14811, Avenue SE to provide 400 to 425 feet ofSSD along the entire frontage would require lowering the profile of 148th Avenue SB for at least 700 feet. Cuts of2.5 to 4 feet would be necessary for over 300 feet. Several hundred feet of· 12-inch water main would need to excavated and lowered. Two power poles would need to be relocated and water meters, utilities, ditches, culverts and driveways adjusted and reconstructed. Retaining walls and rockeries would probably be necessary for the deeper road cut sections. Easements would be necessary from the adjoining property owners. 3. There are pre-existing substandard SSD conditions at both the north and south ends of the East Renton Property. There is a grade break in the vertical alignment of 148th Avenue SE, 120 feet north of the site and the grade increases from 5 to 9 percent. All a result of the grade break, SSD at the north property line for north and southbound traffic is below King County Road Standards (KCRS). The SSD is 75 feet below KCRS for the northbound let 22 04 08: l la Chris Bicket 360 668 1133 p.4 ( ( ( '·· . Variance File October 20, 2004 Page2 direction, and 160 feet below KCRS for the southbound direction. At the south property line, there is adequate SSD that meets the KCRS minimum of 400 feet for a design speed of 45 MPH (10 over posted). 4. There are not any known traffic related safety issues associated with the present roadway. There have been any accidents on 1481h Avenue SE between SE 1171h Street and SEI24th Street during the latest three-year period, for which accident data is available. 5. The applicant revised the proposed design to a 620 foot crest curve that would result in a maximum of three foot of cut on 1481h Avenue SR just to the north of the site. The proposed vertical curve would provide 455 foot of SSD utilizing a two-foot target. 4SS feet of SSD is the minimum KCRS downgrade adjusted SSD for a design speed of 45 MPH (10 over posted). 6. The access point of the subdivision was also moved approximately 480 feet to the north where KCRS requisite 620 feet of entering sight distance (BSD) can be provided. 7. A speed study was performed Traffic Count Consultants, Inc. on S/8/01. The 851h percentile speed northbound was 43.6 MPH and the southbound was 40.4 MPH. Staff's Findings and Conclusions: I. The proposed entering sight distance in both directions for the new revised intersection location onto 148tt, Avenue SE meets KCRS minimum of620 feet for the design speed of 45 MPH (10 over posted speed limit). 2. The S~D along the frontage is limited by the sharper curvature of the horizontal curves to the west and east of the site. The SSD southbound as one approaches the south property line is around 400 feet, which meets KCRS. There is sufficient SSD at the south end of the 650-foot frontage. There is KCRS compliant SSD along the middle portion of the frontage. However, the northbound SSD is not adequate through the northerly 250 feet of frontage. The measured SSD northbound at the north property line is 230 feet and the KCRS requires a minimum of 455 feet of SSD fur the design speed of 45 MPH (with a downgrade correction). Even with a 2-foot target, the SSD only increases to 290 feet. The applicant's proposed re-grade with the 620-foot vertical curve should be acceptable. The entering sight distance (BSD) for the existing driveways along the road would meet a minimum of 545 feet, which exceeds American Association of State Highway and Transportation (AASHTO) minimums for the 45 MPH design speed. The SSD (6 inch target), approaching the new access from the south, would exceed SOO feet and from the north ex:ceed 360 feet. The 360 feet meets AASHTO SSD criteria for the 45 MPH design speed. The SSD beyond the new access intersection would meet a minimum of 455 feet utilizing a 2-foot target. East Renton/Rosemonte -Technical Information Report 3 OFFSITIE ANALYSIS Please refer to the "CamWest -East Renton Level I Downstream Analysis" by Triad Associates, dated November 10, 2004, as submitted to the City of Renton. Job #01-047 August 7, 2008 Page 3-1 :( () CAMWEST-EAST RENTON LEVEL I DOWNSTREAM ANALYSIS KD:NG COUNTY, WASHINGTON Date: 9/19/02 Revision Date(s) 11/10/04 Prepared lBy: GeoffE. Tamble, PE Tyson Wentz Reviewed JBy: Job# 01-047 Rebecca S. Cushman, PE ( , ( ( Prepared By: CAMWEST -EAST JRJENTON Level 1 Downstream Analysis King County, Washington Prepared For: Cam West Real Estate Development, Inc, Issued September 19, 2002 Revised November l 0, 2004 GeoffE, Tamble, PE Tyson Wentz Reviewed By: Rebecca Cushman, PE ( ( ( TABLE OF CONTENTS PROJECT OVERVIEW .............................................................................................................................. 3 GENERAL DESCRIPTION OF PROPOSAL ....................................................................................................... 4 PREDEVELOPED CONDITION OF SITE ...................... . . ..................................................................... 4 DEVELOPED CONDITION OF SITE ................ .. .. ....... 4 0FFSITE STORMWATER RUNOFF ................... . .. ...... 5 DRAINAGE BASIN, SUBBASINS AND SITE CHARACTERISTICS ....................................................................... 5 OFF-SITE AN AL YSIS ................................................................................................................................. 6 SruDY AREA .............................................................................................................................................. 6 TASK I, SlUDY AREA DEFINITION AND MAPS ............................................................................................ 6 OnsiteBasin ......................................................................................................................................... 6 Upstream Basin ..................................................................................................................................... 6 TASK2, REsOURCEREVIEW ....................................................................................................................... 7 TASK 3, FIELD INSPECTION ....................... :: ................................................................................................ 7 TASK4, DRAINAGE SYSTEM AND PROBLEM DESCRIPTION ......................................................................... 8 TASK 5, MITIGATION OF EXISTING AND POTENTIAL PROBLEMS .................................................................. 8 APPENDIX .................................................................................................................................................... 9 Preliminary Plat Map Existing Conditions Exhibit Developed Conditions Exhibit Soils Map Soils Legend Table 3.2.2B -Equivalence between SCS Soil Types and KCRTS Soil Types King County Drainage Basins (Figure 2) Study Area Maps (1990 King County Sensitive Areas Map Folio) Wetlands Streams and 100-Year Floodplains Erosion Hazard Areas Landslide Hazard Areas Seismic Hazard Areas Coal Mine Hazard Areas King County iMAP Drainage Complaints Maps Drainage Complaint List and Complaints Downstream Drainage Exhibit King County Off-Site Analysis Drainage Table TRIAD ASSOCIATES-LEVEL I REPORT FOR CAMWEST, EAST RENTON PAGE2 f ( PROJECT OVERVIEW This section gives an overview of the project site m both the pre-developed and developed condition. There is also a description of the runoff characteristic of the property and the existing soil classification. The proposed project consists of a Single Family Residential Development for 66-lots on 15.92 acres in an R-6 zone. The site consists of two existing lots that total approximately 19.6± acres, with approximately 8.2± acres of sensitive areas to remain undeveloped that include a wetland (please reference Preliminary Plat Exhibit in Appendix). The project is generally located west of the intersection of 148th Ave SE and SE 120 1h St. in King County; Section 10, Township 23 north, Range 5 east, W.M., Washington State. SITE bi \'< bi "< \'< " " I;, s :!: ~ TO 1-4 5 NE 4th ST I -!~ I Vicinity Map NOT TO SCALE SE 116th ST bi ~ "< s C) ~ bi Is' " PARK & RIDE 900 TRIAD ASSOCIATES -LEVEL I REPORT FOR CAMWEST, EAST RENTON PAGE3 ( ( GENERAL DESCRIPTION OF PROPOSAL In general, this project will replace one existing single-family home, a shop, a small covered storage building, and a gravel driveway with 66 single-family lots. Part of the major site improvements will include the installation of neighborhood access streets (sub- collector, sub access, and minor access). 148 1 h Ave SE will be improved with full half street improvements as required by the King County conditions of approval (To be determined). All runoff from the site and the frontage improvements will be collected in the proposed conveyance system. Detention and water quality will be provided according to King County Standards. Two drainage facilities are proposed, one for each drainage basin. A vault is proposed to be located in the northwest comer of the site and a pond at the northeast comer of the proposed project of Rosemonte, adjacent to the north of E. Renton. The dimensions of the proposed lots and roadways will require buffer averaging on the western portion of the site. PREDEVELOPED CONDITION OF SITE The site contains an existing house, a shop, a small covered storage building, and a gravel driveway. The remainder of the site is covered with a mixture of pasture, blackberries, and trees (See the "Existing Conditions Exhibit" located in the Appendix). The site has two drainage basins, one that generally drains towards the northwest and the other that drains to the west. A wetland occupies the western portion of the site where the two basins combine then flows to the north through Honey Dew (Honey) Creek. Overall, the site slopes from east to west at approximately 5-15%. The site generally slopes from 14s'h Ave SE down to the west towards Honey Dew Creek. DEVELOPED CONDITION OF SITE The developed site improvements will be located on the eastern 15.92 acres of the property (See the Developed Conditions Exhibit located in the Appendix). The preliminary plan shows 66 single-family lots with subcollector, sub-access and minor access roadway improvements. 1481h Ave SE will be improved with full half street improvements as required by the King County conditions of approval (To be determined). The detention/water quality facilities will be designed to meet the Level I Detention TRIAD ASSOCIATES -LEVEL I REPORT FOR CAMWEST, EAST RENTON PAGE4 ( ( Standards and the Basic Water Quality Menu from the 1998 King County Surface Water Design Manual. 0FFS1TE STORMW ATER RUNOFF Flows entering the site from the east come from the west half of 148 1h Ave SE. Runoff entering the site from the west and south adjacent to the wetland is collected in the wetland area. The wetland area will remain undeveloped. Runoff generally does not enter the site along the north and south property lines near the proposed lots since the site slopes from east to west. DRAINAGE lBASIN, SUBBASINS AND SITE CHARACTERISTICS The existing site has two drainage basins that drain into Honey Dew (Honey) Creek which, according to the December 1990 King County Sensitive Areas Map Folio, is an unclassified stream in the May Creek Sub-Basin. Honey Dew Creek combines with May Creek over two miles downstream (north) of the site. May Creek is in the Cedar River Drainage basin and ultimately discharges into Lake Washington. The site contains an existing house, a shop, a small covered storage building, and a gravel driveway. The remainder of the site is covered with a mixture of pasture, blackberries, and trees. Most of the trees are located in the western half of the site with the pasture area occupying the eastern portion. The blackberries are located throughout the property. According to the King County Soil Survey, refer to the Soils Map and Legend in the Appendix. The site is underlain with AgC (Alderwood gravelly sandy loam, 0 to 6 percent slopes) and AgB (Alderwood gravelly sandy loam, 6 to 15 percent slopes) soils belonging to the S.C.S. type 'C' hydrologic group or 'Till Soils'. Onsite topography is mild to moderate, sloping to the west at approximately 5% to 15%. Note: The 1990 King County Wetland Inventory did not list the wetland on this property. The 1987 Basin Reconnaissance Program did not list Honey Dew (Honey) Creek in any of its basin reconnaissance data. TRIAD ASSOCIATES-LEVEL I REPORT FOR CAMWEST, EAST RENTON PAGES ( ( OFF-SITE ANALYSIS This section outlines the drainage basin, within which this project is located, highlighting the downstream conditions one mile from the project site. STUDY AREA TASK 1, STUDY AREA DEFINITION AND MAPS This site is located within the May Creek Sub-Basin of the Cedar River Basin. Onsite Basin The site contains an existing house, a shop, a small covered storage building, and a gravel driveway. The remainder of the site is covered with a mixture of pasture, blackberries, and trees. Most of the trees are located in the western half of the site with the pasture area occupying the eastern portion. The blackberries are located throughout the property. According to the King County Soil Survey, refer to the Soils Map and Legend in the Appendix. The site is underlain with AgC (Alderwood gravelly sandy loam, 0 to 6 percent slopes) and AgB (Alderwood gravelly sandy loam, 6 to 15 percent slopes) soils belonging to the S.C.S. type 'C' hydrologic group or 'Till Soils'. Onsite topography is mild to moderate, sloping to the west at approximately 5% to 15%. Upstream Basin Approximately half of 148'h Ave SE along the entire site frontage currently sheet flows into the site. Flows from the frontage improvements will be collected and conveyed to the proposed detention/water quality facility. The area where flows enter the site from the south and west adjacent to the wetland will remain undeveloped. TRIAD ASSOCIATES-LEVEL I DOWNSTREAM ANALYSIS FOR CAMWEST, EAST RENTON PAGE6 ( \ ( ( \ TASK 2, RESOURCE REVIEW "1998 King County Surface Water Design Manual" "1990 King County Sensitive Areas Map Folio" "1973 King County Soil Survey'' There are no apparent problems associated with this project. TASK 3, lFIELD INSPECTION "Triad Associates" preformed a field visit on 4/03/01 to locate any potential problems upstream or downstream of the proposed development. The weather was overcast and approximately 55 degrees with small amounts of runoff in the drainage systems from the previous day's rainfall. See the "Downstream Drainage Exhibit and Table" located in the appendix for a complete definition of the Study Area. Drainage leaving this property is collected in an existing wetland (A) and conveyed offsite to the north through two 12" CMP culverts (BI & B2). The onsite wetland has a slight ridge separating the wetland on the north property line of the site. The runoff that leaves the through the two 12" CMP culverts combines in a drainage ditch adjacent to the north property line (C). Drainage also leaves the site on the north east side (C2) then drains west and intersects with the drainage from Cl. From here the runoff flows to the north through a natural drainage course called Honey Dew (Honey) Creek (D) for about 500' before entering a 24" CMP private driveway culvert (E). The property owner adjacent to the culvert stated that it has only flooded once, around 15-years ago, when a neighbor downstream of their property dammed up the creek to make a waterfall. The waterfall has been removed and the culvert has not flooded since that time. From this culvert, the natural drainage course continues to the north in a well-defined channel with heavy ground cover (F). The final observation of the downstream investigation was approximately 2000' downstream of the site (G). No evidence of flooding or major erosion was observed along the downstream drainage course during the site visit. From the last observed point in Honey Dew (Honey) Creek (G), runoff continues north then west before combining with May Creek and eventually reaching Lake Washington about 6 miles to the West. TRIAD ASSOCIATES-LEVEL I DOWNSTREAM ANALYSIS FOR CAMWEST, EAST RENTON · PAGE7 ( ( (_ TASK 4, DRAINAGE SYSTEM AND PROBLEM DESCRIPTION "King County Water and Land Resources (WLR) Division Drainage Complaints" King County suggests not following up on any complaints before 1990 due to their age and development that has occurred. Complaints Nos. 94-1000, 95-009, 96-0185 and 96-552 all pertain to one parcel (9353). The majority of the complaints pertain mostly with drainage runoff from 148th Ave SE. In particular, an existing ditch was discharging into this property and flooding the basement. King County performed a study of the situation under the Neighborhood Drainage Assistance Program (NDAP) and recommended the installation of a catch basin with a 12" conveyance system to direct the flows away from the home. This project was not completed by the County; however, the home owner installed a similar pipe system as recommended by the County prior to February of 1996. Therefore, the NDAP study was cancelled. Complaint #96-0552 was due to a broken fire hydrant (vandalism), not stormwater, and therefore closed. Additional complaints are within the I mile radius of the project site but are not in the downstream drainage path. The complaints are linked to a private home drainage system and a private road washout due to no drainage system rather than flooding, or erosion of the large drainage course that the site will discharge to. TASK 5, MITIGATION OF lEXISTING AND POTENTIAL PROBLEMS The developed site runoff will be detained to the Level I standard as outlined in the King County Surface Water Design Manual -1998. The KCRTS Level I detention standard requires maintaining the high flows at their pre-development levels for all flows greater than the 2-year peak flow up to the IO-year peak flow. The site is proposing to utilize two detention systems. The detention facility release rates will be based on the existing runoff from the area of the site that is being developed. The wetland area and associated buffers will remain undeveloped. One half of 148 1h A VE SE frontage will be picked up in the conveyance system along the site frontage reducing flooding discussed in the drainage complaints. TRIAD ASSOCIATES -LEVEL I DOWNSTREAM ANALYSIS FOR CAMWEST, EAST RENTON PAGE 8 ( ( ( APPENDIX TRIAD ASSOC! A TES -LEVEL I DOWNSTREAM A NA LYSIS FOR CAM WEST, EAST RENTON PAGE9 ~ Basin: Cedar River Symbol Drainage Component Type Na!l]e, Size Type: sheet, swale, see map stream, dlannel, pipe, pond; Size: diameter, surface area C1 Honey Oew (Honey) Creek C2 sheetflow D Honey Dew (Honey) Creek E 24" CMP Culvert F-G Honey Dew {Honey) Craek ,~, ... -~ OFF-SITE ANALYSIS DRAINAGE SYSTEM TABLE Surface Water Design Manual, Core Requirement #2 Subbasin Name: May Creek Drainage Component Slope Distance Existing Potential Description from site Problems Problems discharg11 -constrictions; under·capacity, ·ponding drainage basin, vegetation, % 1/4 mi= 1320 ft overtopping, flooding,habltat or organism cover, depth, type of sensitive destruction, scouring, bank sloughing, area,votume sedimentation, Incision, other-erosion 3-4' wide drainage·channel 0.5% 10 tt None None pasture 5-15% .14 mile none none 3-4' wide drainage channel 0.5% 480 ft None None 2-3' of cover under driveway 0.5% 500 ft None None 3-12' wide drainage channel 0.5% 500 -2000 tt None None Triad Associates - Subbasin Number: Obsefvations cit field inspector resource reviewer, or resident tributary area, likelihood of problem, overflow pathways, potential impacts. unobstructed natural and man altered drainage channel erosion unobstructed natural and man altered drainage channel if culvert overflows. it will cause no damage to private structures broad drainage channel with heavy vegetation on both sides of dlannel ~v \ ~~~i#l-!~=-~-=--=-:__-_-_: -. =,;;:.01 " -. -. -. --. :::;-::;-._ ~•i.\.o W-----·-... -------~ ~'1 =· ~ -'.SMT.: ·.· : ' " r~ ~ 1112$ John . Hansen 2.86 Ac. ~ -; ::: I , "' Ac. "' ------··· <ii_)•. -;; 1., / ..JN r ,. ,e ® --a:: "' ~!.118~ I~ Wrn. E Broyles I 91 Ac. ._. I ,,,@] r , -,,,~ :-· 0 ~I" George C Davis 2 18AC. ·----·-·-----·---··----·· ,:~• }.'I 1-hlkc H Jye r . ~I "I :s <t - 3 N ®"' .. · ~ @ ;: lv~r M , ,, . ,; @f ~ G (ii I he 1·t \, RENTON E.:. J0-23-! . 2 40!, Q @ C1t12en Fed.S.1 L. Assn . ®- :.:: 0 :: 6)1.4G Ill~~--··----"="-·---·----1· 12!!2."/7 !,O :, t:.J r------··- 1; ~Ftoyu w. sr,aff. ei ux 4.14 Ac. \ 0.16 Ac. >-~ <'..O ~::; "' Q~ :-: I~ ·> ,; .. ,.., :> "" ~~------·-IF ·--"''="''~-----®-l•J L-. .. , . ""·" Fraric·,s P. Brown 4.77 Ac. mfJ 2 s~.o ~ ::)._ __ '"_'_B ______________ ®_"-LI::; ·····---· Stanley J. Petersen (q~ ~I, . ·-------~~~,---ll.U.llA---r:::-=~ ... =---=,--...:::,,-~,--2 :;: I c_ .,.., @ff/o -~~ ::: ~ Henry Uro 4.77 Ac. ~,::: Lionel Lesh ~- <IJ LJI~ ~lg -~ ':; > 0 ·4 % Ac. 81J .. 0) .. -S.P. eazoog R 160 ~ "' ~ c@Ac ~ <@? Ac ~ /J . @) '® ,, '" '" ' ··no <SO :1 (I)~ • '· GJ, 0.SOAc. ~ 11 ~I @i Ii) w <J1 1\ l •1·• : : l.). :, '1 ®-:: :! I ""0 -.,:~11,~:-:-~--~-~.;C;~,;~-~-~-~-:-:--f~~~~~--------~ -6,,...,------...,+.-__:'"'"11-'·"'"!-.----·-':::._.::.:.:.:,;.,.;,,::;.:.....:.::.:.: ____ __:=-Ii "\ I -_@ ,. -· "" .,,. .,,,.,., • ~,.,, (.J..;f' ~ ,., '.[Be ;i · utm) '60J ~ 0 11,!EJ ~ ~.I 0 ~<:t-1- -0 ---1:-: g Robert l.. Stdrzman ~ o -~ "''OA ~-c., c. I~ 5 Ac John M. Pollock First Sav. & Loan Assn. 4.70 Ac :s,,~@] ' .•• I~ ® \ \ [C" ~ ·. · / The od o re'-_L _B_i _n_d_e,.,•:"''·::.'a.' ~----1 · _:.:-:-::=::::..-=:=-~--=--=::~--···-····-.·-·----····-~--------~---·-······--··· ; \1,-N __ _;iu,;11"1.,a-,,-{1) S. 34 Ac. ~ ' l. 24" CMP CULVERT ::: i ();' .· ID 11.--------~ ~ , S.P. 776111 I D ;,,' I 11 {21 @ 111 :,,.I r 3 ~oo.,, 330.':I~ 4/.J , C d'.l) . ·-: "'·" tf I!;,. 8"' I C~ ~ · · "k-· --~ I 12" CMP CULVERT J 12" CMP CULVERT ~-·· @]·.• ~ .l .l I I Donald R. Lar5en 4'jOAc. 632.07 \/,-.~nrP W (irihhlf" Pt 11Y ? :2.G D.r Henry W Owens 3.93 Ac. '. '. i . ) : '/t' "'. l ,. \ I -f ( Map Output Page I of I tll!i Legend TI1e BuHa, /,.,· i.!Yi1 • BtJrfered Setecikm LJ Parco ls . -County B,oundary D U1ku and Large Riven. i M·,\e !<a.di''-'S I-' Streets ;/ Slffl;Ul'l!i ~ 11q'M·b)' II Wt.RO Drainage Complal'lt& -l""') he information Included on this map has been compiled by King County s!aff from a variety of sources and is subjec! to change withoul notice. King County makes no representations or warranties. express or Implied, as to accuracy, completeness. timeliness. or rights to the use of such information. King County shalt not be liable for any general, special, Indirect, Incidental, or consequential damages including, but not limited to, lost revenues or losl profits resulting from the use or misuse of lhe information contained on this map. Any sale of this map or information on his ma is rohibited exce t b written ermission of Kin Coun! . !SID.9.QQ~D!Y I ()!~ .. ~in!~[ I )jg)\'!. I §~IY]!,ll§ I .C9mme.~j} I §.~~L,h By visiting this and other King County web pages, you expressly agree to be bound by terms and conditions of the site. The.Qfilail$., h I l p:/ iwww 5. metro kc. gov /serv I et/com. esri. esri ill ap. Es ri 111 a p 'JS erv i cc Nan 1c~oyer1••i ice1;i,,,_, ,~y',1_(.J'IL1i ,c_···---'-1 _,_1"'1c,.·1 '.ci,un-"n-"ACL...------ / f ( Map Output . -! _• Counly Boundary Stre8lt. ~ tl~~A\lj /'/ 11,b'h'ir. ....... all themes !,1011 ·t--1b<-\-. ><:f 9251 Legend Paroeb. lnootporated An:ia Lakes end Large RfV'ars Stmaim WLRO Drainage Cof'l"()lalnts 9023 Page I of 1 he information Included on this map has been compiled by King County staff from a variety of sources and is subject to change without notice. King County makes no representations or warranties, express or Implied. as to accuracy, comp!e1eness, timeliness. or rights to the use of such information. King County shall nol be liable for any general, special, indirect, incidental, or consequential damages including. but not limited to, lost revenues or lost proms resulting from the use or misuse of !he information contained on lhis map. Any sale of I his map or information on this ma is rohibited exce I b written ermission of Kin Count !Sln9 .. C:9JlD.tY. I 91S Cente1 I~ I §.ervicrui I Comments I Searct} By visiting this and other King County web pages, you expressly agree to be bound by terms and condilions of the site .. I/JQ.C!~ni!~, http ://www 5. metro kc. Q:OV /serv 1~1 /en 111 PC:.:ri ec1·i l"'ll~ln 1: C'l"; lWl n. ')QL~,-.. ; ,..,..1\.1.'"" ---.-.. -. ,1 ,..,,,. { Camwest --E.Renton Drainage Complaints r~:~~.~~;r:;at~:-r::oblem· 1~:p~ 1· Rec Oat~·-· ·· 1-~~1;A~:r·~~:~--1-T~~f1-··;i~-·-·r~~:-i ' I T_J ______ -· ~0552]CLOSED :1995~0009 ·rcLOSEDI EROSIO~J Tc . ·1 Thu 5 J~;,1995 00:00 oci"!35E41·,,;,o,T116THST-r··-·1;-023059357! 627A7\ !1995~0,-ss ·1ci:asE6 r;;coG · ········1 1 c ·· 1 ,ii~.a F;b ; 996 iio oo oo J:iso•fi ,s2si 146TH Avicl st· 11023osii:i"s•[iiisJ1·\ I I I I I I --··-·'"-FLOG C Fri, 23 Feb j 1996000000 rS03l11615f8THAVE SE r023059351626J6 -------···----\1996-0552 CLOSED FLOG R Thu, 14 M -1989-0776 CLOSED FLOG C Mon, 4 De 1999-0151 CLOSED DRAINAGE Cl~~F 00 00 00 __ ,_ _________________ ar 1996 00 00 00 3503 116151148TH AVE SE [ 1023059353F6J6 C 1989 00:00:00 3504 116441142ND AVE SE r060r626J7 --;;,;-,999--11162T2ND AVE SE 102305901626j,'I ·------------------------------------... ---·--.............. I I Complaint Status ;,obl~y~= Dal No I 1988-0790 CLOSED IDRNG ----z· Fn, 23 Dec 198 00 00 00 1989-0140 CLOSED EROSION C ~ 14Mar 19 0 00 11989-0150 "°""l'""="t l"" ,,.,;;; 11994-1000 00:00:00 CLOSED FLOODING C !Thu, 29 D~c 1 i 00:00:00 --- --NOV. 8. 200'1 10: 32AM KC WLRD · N0.339 .• P.'1/20 I "'===--> KING COUNTY .SURFACE WATER MANAGEMENT DIVISION DRAINAGE INVESTIGATION REPORT Page 1; INVESTIGATION'REQUEST Type __ (!,_ ·' --. ! .. Ge-r~ Date: /..?;2-:1~ 21-OK'~ b~: __ :#1 F~'.:f(-/0 ,:)~- Received frorn: (Please print plainly for sconn/ng). 'lAME: /<rm 4'/er:b 4 c;.72,, ~DDRESS:. / /6 / 5"" /#-/? dv'e-::s".< .acatlon of problem, W dlfferent: (Day) (Ev•) PHONE ££5"~ f'? ,j> S. ____ _ State Zip f/? OS-,:--- ----·-----------------------------------~eport8d Problem: 'lat name: Lot No: Block No: )!her agencies Involved; VC: .....fl:!_ .Zl.... ~ Paroel No. 10 ~ 3 etS 1 ,y:.:s 1/4 S T R Kroll __ _ Th.Bros: New @'2-7 & 1 Old .SS~~ ____ _:B:_:a:_el...:n::tlt::lf=::'(:_ _ _:c:_::o:_un:_:c:.::.11..::D.::is:.::t ==·--Ch_ar_g_e ~::; ====------ ESPONSE: Cltlzeri notified on 1-1 (:-?;S:"l)y .k phone_ letter· _ in person · ff~ µ.,7 p11t-e+~o-.% /,...fw.,._, #.,:s ~u <ft?Y kl f4.. ·AJf.vl. ~~-1.'~. ~~ ISPOSfflON: Turned to.lJ!._ on / • 10~,C[f by ::!ff _ Lead agenoy has been notified: ·, OR: No further action recommended because: _ Problem has been corrected. --...,N,...o-p-ro"'"b.,...le-m ... h_a_s .,...be-e-n"'"ld,....e""nt""'ttl-ed.,..., -------,P,_r.,...lo....,r i,-nv-e-st""lg-at""lo-n-a""d..,.dr-es-s-es-p-roblem: -s... Fil• # ' , 'mta problem -NDAP wf/1 nor consider because: ) ..:._ Water originates onslta and/or on neighboring parcel · _ Location Is o~slde SWM Servloe Area. _ Other (Specify): DATE CLOSBD: ~ '2-2...; .J!::L by: ~ l;:,le,4 • C..., NOV. 8. 2004 10: 33RM l(C l!LRD KING COUNTY SURFACE WATGR MANAGEMENT DIVISION DRAINAGE INVESTIGATION.REPORT Hs of fnvestlgatJbn: OMPLAIN'l' #94-1000 METZGER ,vestigated 1-6·95 by Doug Dobkins Page 2: FIELD INVESTIGATION [ect with :t-,{1$, Metzger onsite to discuss her drainage concerns that flooded the bw;mwnt of her house. N0.339 P.5/20 he basemeut WDB flooded and damaged three rooms an!! a bathroom. Mettger lives below road grade and recieves water from 148th ave El 1111d also a ditch to the north af her property th&t is aimed right at her Iiouse. She has a small yard drain in the norteast corner of her lot illt tric9 to band1c, tbis ilow lt 11ppears the small yard drain couldn't handle tho flow of water and overtopped ·lllJll flooded the basement. his roadside ditch has water contributed by three properties to the north of Metzger that drains into this ditch. Mrs. ]\,l_otzger wants to know ho Is responsible for this drainage and who can fix the problem. .( ··-· ·,. 148'MAW SB Investigated by ____________ _ Date. ______ _ . ; ' NOV. 8.2004 10:33AM KC WLRD N0.339 NDAP PRIORITY SCORING ·· . proj eot Na:me: • • J kiw, M.e.taa,~e,'e Project Number: . ~ ' **********·~·*-**************IMPACT CRITERIA************************"*.·•·,. fO;J;liT§~ADQ 0,2 ;iPROPE!;lTI~S Fur. BI~K J:MJ'ACT OB 4 FOR sEV]lBITY XMPACT)i;D (+0 1 2 OR 4) ., . ' Living st;ruotur'13,. finished floor (20 + ..!2._l X -I-+ ..-CL "' Aocess (8 + _) X + = septic/Well. (8 + __ .) X + = 0 Other structure or (4 + _) X + = Q crawlspaoe ~) _z.. _o_. 2 Landscaping/ya-rd/· (l· + X + = parJcing Other property/ (. 5 + -12..:_.) X _.Q_ + -1:L = 0 drainage system Natural resource 3 + ··+ = Q s~~AL = 4(,2 . *********************EVENT FREQUENCY FACTOR************************ Chronic (l+ times/year) ....• 20 2-5 years; indefinite but · o.ften; channel erosion. . . . 10 s-10 yaars ................. . 10-25 years .....•. ~········· 5 2 E.F.F. = . /0 SUBTOTAL X E. F. F. = . ~ ADD 20 POINTS IF IN A TAAGETED BASIN + 0 >2 5 years ••••••• , • . • . . . . . • • . 1 TOTAL IMPACT SCORE = Date: 3/J(il )f£ Rated by /te'N'J · ~-r. -J-ltA~ *************** ****** ** ** *COST-BENEFI'l' RATIO********?*'******"°*****· . 'COST OF SOLUTION ~ $ J~ ~ )P 11'1 AM TOTAL IMPACT SCORE X lOO / COST ~ N'PAl' l'RIOltI'rY SCORE c: fj "id Date: ,3. JJA J iWK I~. Rated by AEM * Not~: F ving &pec.ia from storms < 10 years receives ority. Yes. ------~~===-== .. =·· =-----" ,, ___ -----·----·····-·""•""-"''""-••·-··. :--i--:--. . \ ) mt: 33AM-..,j. --ire '/LRD • .:_+ + _ f .f·-'--+' _j -~~ ' . • I --· ··--••.••• : -···/-· .. ~ .......... -. ···-..---· ·I· .. 1 . , ... NEIGHBORHOOD DI\AINAGE ASSI.STANCE PROGRAM COMPLAINT EVALUATION MEMO DATE: 3-15-95 •\' TO: RANDY SNOW FROM: ALAN MEYERS BJ?• NDAP EVALUATION fOR COMPLAINT NO, 94-1000 KIM METZGER BACKGROUND; The original complaint waa called in on 12-29-94 and Doug D, completed the initial field investigation on 1-6-95. Randy Snow and I spoke to both Mse. Metzger and Schroeder during our f!eld evaluation ?n 3-6-95 on surface water from street•, pasture• and yards north and east of Matzger•s prope,cty which accumulate and flow into a very narrow drainage ditch within the 148th Avenue SI R/W flowing south along the west aide of 148th into the N"E corner of Metmger•e_yard which ie a low point below ·road grade in this neighborhood basin, The flow partially drains into a private OB at the NE corner of her yard which conveys some water through an 8 inch buried CPP pipe west aroµnd the north side of her house and discharges west into the S"hroeder·• s horsa pasture( see complaint 95- 0009) approximately 6 feet lower than l(etzger's beo~ yard level. A small pdnd forms at the Nl!l corner of Metzger'B yard and during recent heavy runoff flooded into her basement filling several bedrooms and a bathroom, damaging furniture, oarpete and walls, ~ha Schroeder's complaint inoludea reported erosion, sedimentation, and inoreaeed m.i.nor flooding aoros~ thei,, large eloping horse yard/paBture from NE to SW towards a low wooded area which develope into the upper channel of Honey creek which is tributary of May Creek, For this report, the horse paature area impacts are considered to impact a horae boarding co11U11eroial business, FINDINGSt Since the problem meeta all of the NOA? project criteria listed below, it qualifies for and haa been investigated under the NDAP program, 0 0 • 0 The problem site is within the SWM eervioe area and does not involve a King county (KO) code violation. The problem site ehowe evidence of or reiorted localized flooding, erosion and/or ee~l.mentation w thin the off road drainage system on private residential and/or commercial property due to later upetream developn1ent (Property other than KO or State roads, parks or eohools), ~hs problem is caused by surface water (not groundwater) from more than one adjoining property and creates impacts beyond the prope:rty owners' control. If there is only one affected property, that property contributes less l;han 75% of the proble~ runoff. ~ ~bis project bas top priority rating under the NillU' because flooding of livi~g apace has ooourred fro= e sto~ judged to be less than a 10 year atot'III event. :&'AGE l OF 3 . ! ( NOV. 8.2004 10'34RM KC WLRD N0.339 P,8/20 OPTIONS AND DISCUSSION Optiona considered to convey the excess surface storm water past both properties include the following, ~ . l. rnetall an underground 12 inch storm drain system from the NE corner of the Metzger•a yard near the existing CB 1 west approximately 130 lineal feet to just inside the Schroeder's property line. Two Type l CBe woula be installed, one at each end of this 12 pipe. From the outlet of the second CB tc be located near the NE corner of the Schroeder's horse yard on the south side of the CB, a scour protection rip rap outlet would convey the storm water safely into a grassed eai-then ewale about 8 feet wide which would run approximately 175 feet · south along the Schroeder's east property line where it would discharge .uito an e~ieting ditch line flowing east to weet down into what appears to be a natural drainage channel which flows weet-northwest. Thia etorm water ewale would include a scour protection structure/facility located at the outlet of the storm drain pipe in the SE corner of the horse yard in order to eafelr·convey the peak flows from the end Of the grassed ewale into the ex sting east-west man-made ditch, 2, Thie option is ei.milar to No. 1 described above, The ditferenoe ie that the conveyance facility from the NE corner of Metager•a yard west to the sohroed•r•e Ni corner would ooneiat of a grass lined ewale in place of the 12 inch storm drain pipe. Thia option would include a U ehaped dieoharge ohute made with several rook gabion/Reno mattresses set on a layer of heavy duty tilter fabric located at the end of the swale at the west aide of Metzger'• back yard. Thie chute would provide soil erosional protection where the storm runoff would discharge from the upper swale down into the awale to be located along the east aide of the Schroeder's horse yard. From this point, the storm water would be conveyed south approximately 175 feet as desorU,ed above in Option No. l. IMPAC~ SCORl!I ~ 220 PROPOSED SOLUTrqN, Si.nae the safe conveyance of the peak eto~ runoff through tbe Metggar•e yard is of primary importance, I recommend Option No. 1 be employed to safely oonvey the peak storm water flows paet the Metzger'e house. since a gi:aased ewa.le lllight erode or wash out and fail resulting in _another basement flooding event, the storm drain facility included in option No. 1 ie preferred based on reliability and aafaty. However, there is a question whether or not a Type l ca and 12 drain pipe would have the capacity to adequately protect the Metzger's yard and home, A small basin study was completed in order to verify the size of storm drain facility required. The results of the study using the SBUH computer model were as ehown below, Baeic Data From Maps and the Basin Area 2STit-2411lt Precip, To Soil Type Areas and ONe, KCSWM Design Manual: 3.6 Acres 3,5 Inches 24,0 Minutes Alderwood Group C Perviaue Area Impervious Area 25 \ of Area ON Area 75 in acres 2.7 86 PAGE 2 OF 3 0,9 98 I i ( NUY, ~.2004 10'34RM KC WLRD N0.339 RESUL!l!S OF !!!HE SBU!t METHOD BASIN ANALYSIS FOR 25 YEAR S!l!ORM: PEAK Q CFS !l!~PEAJC HRS VOI.t!MB CF l,70 7,83 31,065. P.9,20 Based on a design peak flow of 1,7 CFS, a 12 inch concrete storm drain pipe at a 2% elope would have an ample capacity of 5,5 CFS, However, ainca the ma~imum capacity of a norma:rType 1 CB .grate inlet equals only about 1 CFS, an expanded grate or cone type rebar inlet structure would be required along with a below g,,ade rim inlet set in a depression as well as a raised masonry type eemi-cirole wing wall around the CB inlet to help confine and d~eot the pank flows down into the CB inlet, A grassed earthen emergency overflow swale would also be required to convey peak flows exceeding the design peak flow of 1.7 CFS around the house. This project is eatilnatad to coat approximately$ 11,200, The feaeibility of this projeat inoludee the follow-ing· limitations, 1, The clearance on the north aide of the Metzger•e house is tight and will probably slow construotion work along the north property line, Access to the backyard will require temporarily removing a portion of a 4 foot high fence in two locations for equipment and installation of the storm drain along the north property line. 2, Utility conflicts along the north property line are unknown except the existing 6 or B inch OPP dra.l.n pipe shown on the field investigation report. Other utilities could be in the yard areas? 3, the horse sensitive owners as Construction in both yards may be limited by poor soils and yard operations inclµding breeding/foaling,eeason or other horse ieeuea. The project must be coordinated with both required PRIORI!l!Y SCORE= 1.96 FILE NDlll!IVA.t..Doo IN WORD 6,0 AEM 3-7~9. PAGE 3 01" 3 N0.339 P. H'l/20 KC WLRD No'/. 8. 2004 10: 34AM . ~..,,..-~~~~~~;;--·--······· ~ . i3 UNTY SURFACE WATER MANAGEMENT DIVISION DRAINAGE INVESTIGATION REPORT ·-i .._ OfJtail:; of Investigation: " COMPLAlNT #95.0009 schroeder Xnvestigm~d 1-<i·9S by Doug Dobkins f'eJ;li:> 2; FIELD INVESTIGATION . Meet with Mn. Metzger onslte to discuss her drainage concerns that flooded 1M basement ·o1 her ho1>se. . The basement was floocled and <laml\ged tlu'OO rooms and a. bathroom. Metzger lives below road grade 1111d rec!evcs water from 148th avQ SI! and also a ditch to the north of her property that is aimed right at her house, She has a small yard drnin In the norteast co Iller of her 101 that trieS to handle this flow.It appears the small yard drain rollldn' t handle th~ ilow o! water and <M>rtopped ill\d flooded the basement This roadside dltch has water conln'butcd by three properties to the north of Metzger that drains into this ditch. Mls. Metzger wants to kno• who is responsible for this drainage and who can fix the problem. This also affecting lhe down stream neighbor o!Meti,;ger, Raymond Schroeder. complaint mnnber 9S--0009. I called Mr, Schroeder and explained that this would be looked at under the NDA ri,yiew 011 Met2ger co111ple.lnt and we CIPSC bls file to Me12ger. { '-• . ~ I•• 116th ST I ()t} Q.,,$ ~ ~ r ! \Al It )I .:{. rt) IA YI J ~~--l,...liE;iwEl ~x t.1,f: C1:II: Investigated by Date ------- ' i NO'i.. 8. 2004 10: 35RM KC WLRD N0.339 P.11/20 --KING COUNTY SURFACE WATER MANAGEMENT DIVISION DRAINAGE INVESTIGATION REPORT Page 1; INVESTIGATION 'REQUEST Type ~ ' tleoelved by: J ;_ . Date: / / S /_ 9 S OKd by: =114 ~ Fife No. 95-09() ' -... , ~ (D•y) , "(k~~) ,. , Racaivsd from: (Please print plainly ~r scanning). NAME: .Schroeder, l?avmond ADDRESS: 1'170/ .5£ //67?1 Location of problsm, If different: PHONE 2..77-6 I .33-t>10rl-"J~ ~ City tf'e«ror/ State Zip~ Reported Problem: Plat name; Lot No: Block No: Other agencies Involve<;!: No Field I nvestlgation Needad ~ J:!£ .-12-~ .£_ Paroel No. loz.!,o.S 9357 1/4 S T R Kroll 805 E Th.Bros;~ 117 ; · Old 3~ I (Q Basin M B t Council Pl:.! 12. Charge No: WDNSE: C~IZen notified on f:9-,s: ,by L phone...:_ letter _ In person ----:--~ ~1 1 ~ ..(.a i"'.q,"""'. +ti is. LJ.; ,· 11 1."'-t.. lw;.,,J 1-o 't~ ·ttrx:, M~~ e,..JJ.. ~"" "-':u ~ pv-1-I "'--k, ~ JUDA-f rb~, e.fo~r:.,I .Jo '74-/()IDO · · t.. DISPOSITION: Turned to ___ on -----by --- Lead agenoy has been notified: -Problem has been oorraoted. -_-"'"N'"'o..,.p"°ro..,.blTe-:-m~h::-::a-:-s..-be""e-:-nTild"'en""tlii""e""'d,...., ----""P_rl,..o-r-.1;:::n:--:ve=s~tl-:::ga:::tl:-:::o-:::n-:::a-::-dd,..re-ss-~ -Sae File# · •vble, _ 'l'rlvate problem -NDAP w/11 nor oonslcler because: · Water originates onslte and/or on neighboring parcel = Location Is outside SWM~eIVJc Are . _ Other (Specify): . OATE CLOSEO: .Q.iJ i..51?5 by: -5~9~-/~tl(/ NUV . tJ. i:'.ldl'.14 10: 35RMQ O.KC WLRDJ l.L V v l.L;) Cl,/ ),1'1-.l, U. ,_, ' ~ ::::· _.:,...-;;.;;:;,'-,NO. 339 l,..lf"'\Jt""\I ... ,_.. •" ·-· KING COUNTY SURFACE WATER MANAGEMENT DIVISION DRAINAGE INVESTIGATION REPORT ,ns of tnvastlgatlon: X)MPLAJNT #95-0009 schroeder 11vestigati:d J-6-9S by Doug o.obkin.s Page 2: FIELD INVESTIGATION feet with Mm. Metzger onsite to disCUS& her drainage concerns tllat flooded the basement "of her house. . _ .'he basement was flooded Bnd damaged three rooms and a bathroom. Metzger Uvos below road grade and recieveswater from 148ih ave B and also a ditch to the north ·of her property that is aimed right at her house. She has a small yard drain in the norteast comer of her lot ·111t tries to handle this tlowJt 11ppears the small yard drain couldn't handle the flow of water and <mrtoppcd 11114 flollded the ba=nt; 'bis roadside ditch has water oontrlbuted by three properties to the north of Metzger that drains Into thls ditch. Mrs. Metzger wants to know rho is responsible for this dralnago and who can fix the problem. This also affecting the down stream nolghbor of Metzger, llHymond chroeder. complaint nwnber !15--0009. I called Mr ,Schroeder and explained that this would be looked at under Ibo NDA review on {e~ger complaint and we close his file to Metzger. ) ,h:· ,Y IIROEDER 0009 -- · .. •., ···-.:::;~--\ ·• •. -., ... \::~ ........ ', . ······--..·J·.:.·;·:·····"··-~ ! : '! j / i:: 1 •! 148THAVB SB Investigated by-------~----- !se 116th ST ! Date. ____ ~-~ ., ..... N0.339 P.13/20 ---KING COUNTY SURFACE WATER MANAGEMENT DIVISION DRAINAGE INVESTIGATION REPORT Page 1: INVES1!GATION "REOUEST. Type c... Received. by:. J. J.., .... --··· ....... ----·· ..•. Date; . .2-8 ~ <Jt__ ... :~K'd by: ... _~··-··File _No .. ~ (c -_6_.l_a~ Received from: (Ple~u prlnt plainly lor ~nnino). (Doy) ·NAME: Oa lie ::hhnson · RHONE 25"S-Zc/8f,_· __ _ . : ADDR:SS: . //62 5 .JL/tf,h·IJ/1'/;, .5i: Clty.·feo--m17 · Slat<; Zip9g,Q.; ·.--'"I:~·-:-·, .. ,-.-•,-':. •' "'· .. -. .' ··.··---·-.:..·~· ·-----.. ···-~--. . ' ' . . . . '.,Location of ~'.::'~le".'.i.~'.'or:~g /:.9._~~~~(-.17~$!.i ~qr':fa~-~&Af(' -&-~~?{g~ . Reported Ptoblqm: · ·· o..+ /161&" l~(J /'t()E .SG' l:>P , . . ~17~ -~n? . )/~;. ·.6.al"/l e:n /1/8.rt,Au /~ P/e1odt'n3 ·+he .. Joh'.ason:S and Plat ;-\2,r,,c;: · O~h~r ~gancl~s, involved: fnef--iKer 5 . ;7rtJp-/y, ?he (!ult1erl fC'n /l/-B--f--· AtJG. SF /Jfff).S 1V Bi: ., . tn larjed,,· . ; Lo: No: ::i1ock No:· : " !·lo riald investiga,lon N;;&ded __ _ Or\: No fu~her action recommended 9e1 ·ro· ~sad egency has bean n'oth1ed: :_£:.}.~:lll..,..,-~Uttt~.:......./4.Ll!:......!,Z......:::::._· -..,-,.--,--,--...;..--,--.,..,..-"-:;;:···.;.:_\_;;_·· _ P,oblern hu been corracted, _ Prior investlgatlo,, addresses pro S.e Fil•# · · ' \ _ Privzre problem -NDAP will not r::onsider beCe(!se; . . _ Water originates onshe and/or on neighboring percal . . , _ Location. 1~ outside SWM S~};;jea, . . _ Othllr (Spach')•): DATS Cl.OSED: -!:-1ll19 C. b\~ ___/'!:'(/ ~rDro/f.J)S' ·.NOV, 8.2004 ,.10:_;35AM KC WLRD · ·NO. 33;1 ~. 14/20 ~"" :.s:*''' ,j \ -,--~_.,.., .,i;u~..ir¥1t.l..:Ui~bl/!ljjlte'j!jjt'#W-· ...... -.n '=i" #=' ;,,·, 1'11.tNF""l•';"I""'· -----. ' ""'"' ,_,, ________ _ COMPLAINT 96-0185 JOHNSON, DAVE Investigated by Doug Dobkins on 2-21 ·96 Mr. John~q_n was not present at the time of investigation. I left a door hanger with card and phone#. Mr. Johnson Is eoncerned about the runoff from 148th . avenue SE flooding his property and the neighbor to the north of his property Metzgers. There is a catchbasln at the northeast comer of SE 118th and 148th Ave SE which backed up during the storm on February 8th. The pipe under 148th could not handle the capacity and backed up onto 148th and ran to the west onto Johnson's property and on Metzger's property. This problsm looks to be created by the Intense storm on February 8th. lwlll call Mr. Johnson to find out whether the water backed up from tlie catchbasln or bypassed the basin and ran·down the driveway. NOA proJeot'on the neighboring property of Metz.gar. Both live below road grade. LEFT MESSAGE WITH DAVE JOHNSON ON 2-26-96 SE 116TH ST OPEN DITCH . 148TH AVE SE NUV. !:i.clJ04 10: 35AM KC WLRD N0.339 KINC:i COUNJY's'URFACE WATER MANAGEMENT DIVISION DRAINAGE INVESTIGATION REPORT Page 1: INVESTIGATION REQU,EST Type G· Date: :2 • 2.3. q!, OK'd by: 1/d· FIie No. q (o-5 5 2-• le\ Reoeived from: · (Pleau print plainly for scanning). (Day) (e.ta) IAME: __ --'t-"a.O",y<-'m..:...:..:o::;_n..;..=d'-'-' __.L"-''-'-'rY]..,_._ ________ PHONE 23:i-9 7£!5:" ____ _ .DDRESS:.--'-'/ (c.,,6~(~5~_.,_l_,'-1'"""8"'--71-,---'-'!1c..c.V:..:c'£_.........cs;=c'~--City R errton State. __ Zip 1805'1 ocatlon of problem, If different: 'eported Problem: . lat name: ;::1de-cl rtJadwa.y, cla/rn. . ,·.-.. tjua.,,r-er r'9-o,..,.., . 6e ?:· 1 / r; .9 <"<- Lot No: Block No: ther a·gencles Involved: . No Field Investigation Needed __ _ · dnltltJ.s) · ---~~~ p.)~ ( 0 23 5_ Parcel No. /02 3 0!5 Cf 3 ~ .5 ~II .f'D5 e., Th.Br~s: NewW2/e ;:J'{g 1/4 s .. T A Old (t}2.1 Jj.(p Basin IY\/9( Council Dist /.p . Charge No: ~5.D,3) f::. 3 :SPoNSE: Citizen notified on Ji2-9(, by hone -letter -in person SPOSITION: Turned to~ on 3 ;tf1/p_ by~ OR: No further action recommended because; _ Laad agency has been notified: --------.,..:---...--=--,-----~~-,,.-er-....,.,.---, _ Probliam has been corrected. _ No problem has been Identified. Prior Investigation addresses problem: -Sae FIie # • . ( ~ · 'Ire problem -NOAP WIii not consider oacause: · . _ Water originates onslte and/or on neighboring parcel · _ Looatlon Is outside SWM Servlc~ Area. 1ATE Cl-0.SED: ~__!i;~ by:·~ . ---.. .15_ Other (Specify): ~b..1/k-Lc:qJ.-i-J-,;iv... .~~ .,_~~ .. NOV. 8.2004 P.15/20' •. ,,.,,.._., ..... ,i... •••.• ( \ i Date: Marcil 7, 1996 Date of ltl-vestigatiom March· 6, 1996 FM: Gary-Paul Relnko .Rll:1 Evaluation for Complaint#: 96-ll552 Tim Raymond fLynn Metzker 11615 148th Avenue SE Renton, WA, 98059 DI\YP 235-9785 Ms. Mc!Zker's home lies below the road olmitlon of 148th SI!. She stated that durltig the heayY .rainlalls otFebnwy, 1996, she experloiu:ed water Inside the house. Two basement living rooms were dlunagcd. The carpets had to be replaced 1111d the walls repainted. Ms. Metzker said the water is flowing il'om SE 116th Street., IIVIII' the propcrt;y to the north and also down a culvert in the front of the property to the north. The culvert water flaws Into a CB in tho nottheast com« of hor propetty and then outfalls next the the bedro!>m windoWII. Tllls has bappollOd at least once a y= .In tho four~ she has owned the property, Sho was not aware ofthe:water problems when she bought tho home. ' She fcela that water ls coming down the street (148th) ftom some recent development I recollllllend that this be mmed over tho the NDA Program fur 1iJther study, \~ 1 ... ~11.e. 1 -t .'.,/.!I ·,o; ·"'' Dnte: March .26, 1!196 Neillbborhood Drainage As1lsta11ce l'rograQl Complahtt Elvalnatlon Mllmo Date of Jnvcsdgitlon: March 2S, 1996 FM: Jeff Jacobson RE: NDAP Evaluadon for Compllllnt # 9G-OSS2 Tim Raymond/ Lynn Metzker · U615 148th Avenue SB Renton, WA 98059 Day P 235-9785 Comnlaln! Chrqnology Original: Field Invest: Fleld.Bval: Old Files: BBckgro)Uld 2-23-96 3--07•96 3-25-96; 4-02-96 !14-1000, 95-0009 Tim Raymond, the complainant, called February 23, 1996. The house silB 5 to 10 feet below the sutfaco of 148th Avenue SE. He·says runolffrom the roadway 120 feet to the north(SB 116th Street) ls flooding his baSClllC(lt. This road is not maintained by the county. This has been a re-occurring problem for him e'Vllr since he bought the house. Mc. Raymond Is the first owner of the house, ae claims this son of flooding occurs !bur or :five times a year. Lynn Metzker, the current~ oflhohouse, had oalledinacomplaint!Jwemberofl994. The investigation was tunted into a Nl>A review. The NDA re"Vlew wa, !lMll a top priority flC()Ie. However, be:fbni any coDStruction took place the owner of the house had installed a catch ba81q!conveyance SJ1i1eD1 of bis own. The system installed by the owner was very similar to tJie system ·recommended by the county. Therefore, the ooumy elected to cancel the construotion of the proposed NDA•funded conveyance system. Endings l>Uling my site iuvesli8lltion on April 3, 1!196 I held a conversation with Mc. Oerspaob. Mr. Gerspach is . the propet1y owner abutting Ms. Metzker/Mr. RIIYntond to the north. He clalms h~ e,c;perienced some minor flooding on February 22, 1996. Apparently, some vandals had destroyed a Jlre eydrant on the lntcrseot!on of 148th Avenue SB and SR116th Street. The fire hydrant Is located 1/2 blook uphill from lhll Metzker hott1e. Mr. Oerspach noted tho Metzker household eicporlencod damage ofthe living space hi the basement due to thls act of vandalism. · I called Ms. Penny Merrlll with King County Water/Sower l>Jstrlct No. 90 on April 3, 1996. She confirmed an Qot ofvlU!dallsm had o=ed involvlllg fire hydtants on FeblUllrY :22, 1996. Additionally, she had a teoorded complaint 1rom l 1615 148th A venue SE on this night • the night of the vandallsm. [Er~~· .. ~: ~~30: 37AM Of.1:·, ' ' ' . l<C WLRD N0.339 P .18/20 ' \. Tbjs address is Ms. MelZkers'. Ms. Metzker placed II call to SWM on the ibllowing date: February 23, 1996. This drainage, problem does not qualify under tho NDA :Program criteria. The problem was not pan of a natural stotm·,eVtlllt. The problem was caused by an isolated act ofVQildallsm and not a storm event This was the first floodlng compl!Ullt received since the comp!,unt logged ln December of 1994. Mr. Raymond did upgrade his storm conveyance i;ystetn since the original complaint My conversation with Mr. Raymond wbil,fon a site investigation, March 25, 1996 reviled the catch bnsln systllm located on the north~ pol'tion of the property was adequato :for the water received. At that tim0, Mr. R-l:yrnond's pri.mary concern was the sheet flaw coming off tht neighbor's propen;y. Thls sheet flow was obviously an Moated event caused by the dwnllged tire llydrant. Having recoiYed no addltio'llal cmµplaints :for the last two major storm =ts, November, 19'95 and February 8, 1996, respectively, SWM considers the file closed. rn: cf(RM--KC WLRD NO. 339 . KING COUNTY WATER~ RESOURCES DIVISION DRAJNAGE lNvESTIGATION REPORT .oBLEM:, boi1nN:)V £SC}i,MID BY: .0/N'f Page I: fiMsTIGATION REQUEST Type (2_ naie:2fzz OK'dby:~;No. qq~Ol:i/ Received from: (Day) rL}?? ) PHONE 254: -3gzg (Eve) ~< _ ___.) City /8;N,TVN St.ate. __ Zip @Qffj Location of problem, if different: __ Jt name: Lot No: Block No: Other agencies involved: No field investigation required...,...,.,-- ~ . ~ .,*,r_4ta1t~Wiita&iii\i-l¥iirlMM Y-i S . T R Parcel No. 10'2..ol>'? -4,r:i4 2-Kroll S'll5 E. Th.Bros; New ll'2.lo ::J '] . ' Old '3'5 1)4', B®Jn ,w:t{ CounC)IDistrfot& · · CbargeNo. ______ _ Rl!SPONSE: Citiz~ A~ on 3/r:r(!if. by: ~ phone lett11r ·-in person l..., "(f"'[: ,,A,fl;r-t:~/FI' 'T~"9-r-_ sf!",( ·CPc>UL-0 /V~.£> A-(i/e,?p.1~ fe;c /1 rr ro r.AJ ~ If/\ .,~ -e:.s7.)f 8 GA-I ,r ,i>A'.#.1;./A-.. ~ °"v.a,..o .+JI;.)µ 6-W'f' H ~,t ,r'/.r.f' ,J 1/111.d~ DISP·osrrroN: Turned to_ on by_ OR: No further action recommended because: _ Lead agency hM helll1 notill!!d: __ ·-------------------- .....:.__ Problem has been corrected. __ . No probl61ll has been idenililed. _ Prior investigation addresses problem: , SUl:Wt# , _ Private problem -N,DAP will not consider because: ( __ Water originates onsite and/or on neighborlng parcel. Location ls outside WI.RD s~.4ea. _Other (Speoify): DATE CLOSED: °J 1 7 I if By: _:_tfj_ . jtv{<:Jf/2.l't/f/)~ ·i ' ( •. Complaint 99·0151 Rutledge Investigated By Pat Simmons 03/01199 I met with Ms. Rutledge about the drainage that flows in the Rorse pasture behind her home. Tue water flows out of a pond/wetland and through a swale that Is about 50 feet from her South fence. The water is about 2 feet wide on the West edge of her property and 5-6 feet wide on the East side of the.parcel. This appears to be a natural drainage course that flows wh1111 lbe wetJ.and/pond get full enough. She would like to keep the stream narrow to allow more room for the horses. I stated that I would look into (!le DJl!:ur<l of this drainage to see how it Is protected under CU1Tont codes ll!ld provlr,le her with some information on the rostrlctiollll near the drainage. 142nd Ave SE r D Pond/Wetland 11642 Rlltlodge Pasture Drainage Swale -NOl!JNJHSVM ~~ i ·~ • I i ,, ,U/J3d0/Jd NYW/J/H:)S/IJ3'10)1311NI ' •• I !J J !MOJJ.fr!J3m/ J1.S~3 I 4::\ ! l ! 1N3Wd013A301S3MWY:) ! ... ;! 1 Y1d AIJYNIW/13/Jd ,E ~ . , . ' ,1:, ~~ e --· t ;x"..; . ' • tt~ • l ' C ~ "' 2 : ! " ' -i <Ii s . ~' . ,..,:,: ' ; ~ • ~-~ -·-• ~; "i I" t>' ~ ~ g! ~ ~ ~ = t\ ! ~;p niR • • • • • b~~ ~Ii;, § s ' ,, >h-g • i ~~~ : . ~ ! -'F~•, . • :: :: ... ~ :: =! ~ 0 0 <> ; ' • " .!! .. ~ ~ ~ !i • ::E :;:: w "' ui C, a: I z f ... i <") '1); N a: ! 3: I- I ' I I j ! I I '.uNnoa !JNJ:>1 -,~ ". " . ~u !} u,r t i!d! I- , I G!!,: IU'IUo ,_... ... --j>'M , ..... ,r,_ t::::;; .. _ .... """_ ... _ ,_ ..... , ........ ~~ ...... un 'ON .;-_::1; ri: . ;~ ' --·-It ~;i ;~: -,~e r-,/' -;--J . / . . ,) :; /._. ' • j V • • • -' "·' •• / < ···-·--·(-·· ........... : r--· ·-. + -·- ! !--~ --. --·-· --I ---- " j,;.;··,i e ... "' .= 0 .! ~-,~\·,, .; .l. .. ,~ .. j :s 0 ~-,.. ,,. ! .... "I " • s I • 6""'tdd(H1t\"-.-.w\•f1MQ\JH110\s..l~ -} . -~-~-"'- N019N/HS'1M 'J.lNnoa DNl>I .... = ~ .... Q= 0 a S!Q ..:. -·~ ~!! 0 !.~ ~§ g " ~ E I! ~ 118/HX3 SN0/1/GNOci 9NJ1SJX3 (/) w ' I • D >-- <( u 0 (/) (/) <( .:,>) 0 <( °' >--... 0 0 N Q ) I o~( b o" ,' ~ ., 0 ' i • ' .~-~·········· ···~ ·•·•· ........ . ...... o··· 0 N , .. 0 0 .... II .... ~ w ...J <( lil () Cl) 0 , ... --.,.,,·· ..-··::.:,.:;.:.:: . • 0 l \1on1 daouo:i\ s•J!J6"'0\L vo LO\Sl:J3rO!ld\ :3 . ,.. __ ........... ' ·-· --~ .. . ,- N01DNIHS'1M 'AlNnO:J fJNl!i I I \' 0.1N3H .1Stt3 .lS3M/lllttCJ . i . . . : . _, -··-.... ,_, ;~;='-t[' -!,--:· ··, ........ ,-_,..,:-'.T. •,. ·. ·1. ;:t .1 :·I.· I ...... 1 I 1.':· ' 1' C ' ....... ·, 1/8/HX:1 SN0/1/0NO;J 03d013A30 I ! 1 • ·.;;; ~t s: . ;;:.:.. 1·, ~> ·, -in t• ·•ll, ....... ;"(" .. PJ._ .t I .I I, ~ • I' ~ <lf . ~·':: ' ... ~k· ., I :; i I ~ i , . I f't'•• r ~ r !'(-··· I> I I I I . ,, : ii ··""J· C < 2' C C " (:;. \) .... n. ~ . . . ·. ~ AgC .. .,,_ ., ,. I I I I ---..-,1!:.. .. -:""··;,;Jf"""--· i I I I ,--.i,.,.,=,==~,"~1--..... ··' I I I I I I AgC " . ,,. " ,, ,, ,, ' AgC 14 ., .. ,! "' . " " _ _.i([ Akf "'"". ······ [>8 ... 3.2.2 KCRTS/RUNOFF FILES METHOD-GENERATING TIME SERIES TABLE 3.2.2.B EQUIVALENCE BETIVEEN SCS SOIL TYPES AND KCRTS SOIL TYPES SCS Soil Type scs KCRTS Soil Notes Hydrologic Group Soil Group Alderwood (AgB, AgC, AgD) C Till Arents, Alderwood Material (AmB, ArnC) C Till Arents, Everett Material (An) B Outwash 1 Beausite (BeC, BeD, BeF) C Till 2 Bellingham (Bh) D Till 3 Briscol (Br) D Till 3 Buckley (Bu) D Till 4 Earlmonl (Ea) D Till 3 Edgewick (Ed) C Till 3 Everett (EvB, Eve, EvD, EwC) A/B Outwash 1 Indianola (lnC; lnA, lnD) A Outwash 1 Kitsap (KpB, KpC, KpD) C Till Klaus (KsC) C Outwash 1 Neillon (NeC) A Outwash 1 Newberg (Ng) B Till 3 Nooksack (Nk) C Till 3 Norma (No) D Till 3 Orcas (Or) D J Wetland Oridia (Os) D Till 3 Ovall (OvC, OvD, OvF) C Till 2 Pilchuck (Pc) C Till 3 Puget (Pu) D Till 3 Puyallup (Py) B Till 3 Ragnar (RaC, RaD, RaC, RaE) B Outwash 1 Renton (Re) D Till 3 Salal (Sa) C Till 3 Sammamish (Sh) D Till 3 Seattle (Sk) D Wetland Shalcar (Sm) D Till 3 Si (Sn) C Till 3 Snohomish (So, Sr) D Till 3 Sultan (Su) C Till 3 Tukwila (Tu) D Till 3 Woodinville (Wo) D Till 3 Notes: 1. Where outwash soils are salurated or underlain at shallow depth (<5 feet) by glacial till, they should be treated as till soils. 2. These are bedrock soils, but calibration of HSPF by King County DNA shows bedrock soils to have similar hydrologic response lo till soils. 3. These are alluvial soils, some of which are underlain by glacial till or have a seasonally high waler table. In the absence of detailed study, these soils should be lrealed as !ill soils. 4. Buckley soils are formed on the low-permeability Osceola mudflow. Hydrologic response is assumed to be similar lo lhal of till soils. 1998 Surface Water Design Manuol 9/1/98 3-25 QJIDE TO MAPPING UNITS For. a .full description of a mapping unit, read both the description of the rnapping 1.D1it and that of the series to which the mapping unit belongs. See table 6, page 70, for descriptions of woodland groups. information is given in .tables as follows: soil Other I Acreage and extent, table l, page 9. Engineering uses of the soils, tables 2 and .3, pages 36 through 55. Town and country planning, table 4, page S7. · Recreational uses, table 5, page 64. Estimated Yields, table 7, page 79. Map synt>ol Mapping unit Described on page ·AgB-AJden.'ood gravelly sandy loam, 0 to 6 percent slopes---------- •AgC-AJderwood gravelly sandy loam, 6 to JS percent slopes--------- AgD AJderwood gravelly sandy loam, 15 to 30 percent slopes-------- AkF Alderwood and Kitsap soils, very steep------------------------ AmB Arents, Alderwood material, O to 6 percent slopes 1/---------- AmC Arents, Aldenrnod material, 6 to 15 percent slopes-1/-------~- AA A.rents, Everett material 1/-------------~----------=----------- BeC Beausite gravelly sandy 10am, 6 to 1S percent slopes---------- BeD Beausite gravelly sandy loam, 15 to 30 percent slopes--------- BeF Beausite gravelly sandy loam, 40 to 75 percent slopes--------- Bh Bellingham silt loam------------------------------------------ Br Briscot silt loam--------------------------------------------- Bu Buckley silt loam--------------------------------------------- 0, Coastal beaches----------------------------------------------- Ea Ed EvB Eve EvD EwC InA InC , .. r "l Kp'i, KsC Ma Nee Ng Nlt No Or Os OvC OvD OvF Pc Pk Pu Py Rae RaD RdC RdE \ Earlmont si-1 t loam-------------------------------------------- Edgewick fine sandy loam-------------------------------------- Everett gravelly sandy loam, Oto S percent slopes------------ Everett gravelly sandy loam. S to JS percent slopes---------·- Everett gravelly sandy loam, JS to 30 percent slopes---------- 'Everett-Alderwood graVelly sandy loams, 6 to lS percent s)opes------------------------------------------------------ Jndianola loairry fine sand. 0 to 4 percent slopes-------------- lndianola loamy fine sand, 4 to JS percent slopes.------------- Indi anola ]oany fine sand, 15 to 30 percent slopes------------ iitsap silt loam, 2 to 8 percent slopes----------------------- .,ICitsap silt loam, 8 to 15 percent .slopes---------------------- Kitsap silt loam, JS to 30 percent slopes--------------------- lCJaus gravelly loamy sand, 6 to 1S percent slopes------------- Mixed alluvial land------------------------------------------- Neilton "Very gravelly loamy sand, 2 to JS percent slopes------ Newberg silt loam--------------------------------------------- Nooksack silt loam-------------------------------------------- NoTma sandy loam---------------------------------------------- Ore as peat---------------------------------------------------- Ori di a si ]t loam---------------------------------------------- Oval] gravelly loam, 0 to JS percent sJopes------------------- OvalJ gravelly loam, JS to 2S percent slopes------------------ Ova)l gravelly loam, 40 to 7S percent slopes------------------ Pilchuck loamy fine sand-------------------------------------- Pilchud: fine sandy loam-------------------------------------- Puget silty clay loam----------------------------------------- Puyallup fine sandy Joam-------------------------------------- Ragnar fine sandy loam, 6 to IS percent slopes---------------- Ragnar fine SU1dy_ loam, 15 to 25 percent slopes--------------- Ragnar-lndi ~o~a association, sloping:}_/--------------------.:- Ragnar so1l---------------------------------------------- Jndianola soil------------------------------------------- Ragnar-Jndianola association, moderately steep: 1/------------ Ragnar soil--------------------------------~------------- Jndianola soil------------------------------------------- 10 8 JO JO JO 10 J J J 1 12 12 12 13 J 3 14 14 15 15 16 16 16 17 16 J 7 J 7 18 18 .] 8 18 19 19 20 20 21 2] 22 23 23 23 23 24 24 25 26 26 26 Capabi I ity unit Sy,,bol Page IVe-2 76 IVe-2 76 Vle-2 78 VI!e-1 78 IVe-2 76 IVe-2 76 IVs-1 77 IVe-2 76 VIe-2 78 VJJe-1 78 lllw-2 76 Ilw-2 75 I·J1w-2 76 Vlllw-1 78 Ilw-2 75 l Ilw-1 75 IVs-1 77 VJs -1 78 Vle-1 77 Vis-I 78 IVs -2 77 JVs-2 77 Vle-1 76 II I e-1 7S JVe-1 76 VJe-2 78 VI s-1 78 Vlw-2 78 Vis-I 78 llw-1 74 Ilw-1 74 11 lw-3 76 VI IJw-1 78 Ilw-2 7S JVe-2 76 Vle-2 78 VII e-1 78 Vlw-1 78 JVw-1 76 Illw-2 76 llw-1 74 JVe-3 77 VIe-2 78 -------- JVe-3 77 !Vs-2 77 -------- Vle-2 78 YI e-1 77 Woodland group Syri>ol 3d2 3dl 3d] 2dl 3d2 3d2 3f3 3d2 3dl 3dl 3w2 3wl 4wl 3w2 2ol 3f3 3f3 3f2 3f3 4s3 4sl 4s2 2d2 1d2 2d) 3fl 2ol 3f3 2ol 2ol 3w2 3wl 3dl 3dl 3d) 2sl 2SJ lw2 2ol 4sl 4sl 4sl 4sl 4Sl 4S2 V. S. GOVERNMENT PRIJ-ITING OFFICE ; U13 0 -468-U& , . I ·' ". ~ I ., n / I 1, I \! ' ·\ ) .·J;. 'I ·, ( ' .. ' •I ,.,. .J,· I', i. II I '. ,. f'·'·; I ·) I . 1•. ,I! I I,..;., ,, !/ 11 ' :i ,, I) ·->-1 \I )I ~·~··· .. !), i. II ~ a, ~ 'C C a, 'C ::, C s ::, s C I C ! ... 0 I .b. ::, (/') I • ~---.·· -•. ,., . f- l /" .:.1 : • <-•" ,• " E ·-. ·-C C. • C. .,,, ,. .. C'O ,c s~ <tl ~ 0~ .. ~ 5 ... It ,,.j._.·v· / -·' ' \ .,:n ! ·, ', ··~'.J.·" ' I, fi I '. i' I·, ' ' \i . <".J .(/~( . . I ··r. ,._. i • .. 0 ' I - / II . .;. . ( 1/2 0 6.m,/ MILE t N The bounda,in· ol lhe seni.ilive ,reas dis· Played on these maps are approximate. Addlllonal sensitive areas that tiave nol bnn mappM may be prnent on a deYtl· opment proposal site. Where dilferencu occur between wtial iS illustrated on lheie mapi and lhe site condilioni., the aclual pre- sencr or absence on the site ot !ht sensitlv, a,ea . as dtllned in lht seni.ili'Jt Arn Ordinance -is ll'lt legal control. Numbered wetlands, except 1hose wltn an "a" or "b" designation are lnduded in lht Kin£ Count)' Wetlands /n~·,ntor-y. The loutlons of wttlandi designated "•" have been verified on \ht site b;· a variety ol sources. Wetlands designi!ted "b'' ue map- ped in the U.S. Fhh and Wildlife Servicr Naliorrol Wrrlands ln~rr.tory, t111I H1eir l~ca- llons have nol been fif!d verilitd. Wetlands Open Water ==:=:;1 Basin Boundaries Issaquah I r,'-~'· ,<11~ & 9 " :f~t -. 0 ' / 0) • • • • • ·, .. i '\'", '· /:: ' ' " ' / 0 w _, :E ~ ::fj,'Y' ' '/·/ '.,_,):.;,. .. "' '-t ,, ' 0 \i't' !J / . . )· I ' . ,. ··{''"'\" '\:,,. 1 ··,:..~:· .. ·.··\ .·.1 It_ ·-~"'·: J 0 - w ..., :s' / East Renton/Rosemonte -Technical Information Report 4 FLOW CONTROL Al\lD WATER QUALITY DESIGN One detention facility is proposed to provide flow control and water quality treatment for this project: a combined wet pond located in the northeast comer of the site. Detention volumes are sized with King County Runoff Time Series (KCRTS) program. In accordance with the 1998 King County Surface Water Design Manual, the site will release water at the Level I Detention standards (Conveyance Protection) and the Basic Water Quality Menu. Dead storage in the pond will be used for water quality treatment. KCRTS was developed as a hydrologic modeling tool for King County. The runoff files have been pre-simulated for a range of land cover conditions and soil types for different regions of King County using the U.S. Environmental Protection Agency's HSPFIO model. The HSPFIO model was calibrated with regional parameters developed by the U.S. Geologic Survey and King County Basin. Planning. The KCRTS program simulates the project hydrology through the scaling, summing, lagging, and level-pool routing of runoff files. The KCRTS program includes a group of analytical tools to provide statistical data on the generated time series files. The KCRTS Level I standard requires the project to match peak flows for the 2-and I 0-year event from the developed site with the respective flows from the predeveloped site. The detention facility characteristics (facility dimensions, discharge structure configuration, etc.) are manipulated to adjust the facility outflow peaks until it approximately matches the 2-and I 0-year storm events. The drainage concept includes some areas that must bypass the proposed facility to recharge the wetland. Runoff from this bypass area is modeled and compensated for within the new facility. Refer to the Existing Conditions Exhibit and the Developed Conditions at the end of this section for the delineation of these areas. A portion of the wetland recharge area (lots 72-75 roof drainage area) is directed to a flow splitter (CB 6B). All flows below the 1.1 year storm event will discharge to a level spreader adjacent to the wetland and flows above the 1.1 year storm will be connected into the conveyance system directed to the pond. Job #01-047 August7,2008 Page 4-1 East Renton/Rosemonte -Technical Information Report A summary of the results from the detention calculations are included in the following pages. Actual KCRTS output (i.e. basin summaries, stage/storage/discharge table, inflow and outflow durations, etc.) is located at the end of this section. According to Table 3.2.2.A from the 1998 KCSWDM, the estimated Regional Scale Factor for the Rainfall Region is a SeaTac value of 1.00. The site is underlain with Alderwood soil, which is classified as hydrologic soils group "C" or till soils. (Please refer to the Soil Conservation Services (SCS) map and SCS legend located at the end of the section) 4. 1 Detention Facility The pond receives runoff from the northern and eastern portions of the site depicted in the Developed Conditions Exhibit, located at the end of this section. This also includes runoff from frontage improvements along the western half of 148th Avenue SE. This pond will provide live storage for detention above a permanent pool of dead storage for water quality treatment. Existing Conditions Basin The existing conditions has been modeled as till pasture based on the existing conditions of the site and existing impervious area includes 148th A venue SE. The existing ground cover characteristics are listed in the following table. Existing Impervious (148th Ave SE and houses) Till Forest 1.07 acres 2.35 acres 14.45 acres Till Pasture KCRTS Peak Existing Flows Flow Frequency Analysis Time Series File:ext.tsf Project Location:Sea-Tac ---Annual Flow Rate (CFS) 1.34 0.647 1. 31 Job #01-047 August7,2008 Peak Flow Rates--- Rank Time of Peak 2 2/09/01 15:00 7 1/05/02 16:00 3 2/28/03 3:00 Total 17.87 acres -----Flow Frequency Analysis------- --Peaks Rank Return Prob (CFS) Period 2.42 1 100.00 1.34 2 25.00 1.31 3 10.00 0. 990 0.960 0.900 Page 4-2 East Renton/Rosemonte -Technical Information Report 0.331 8 8/26/04 0.751 6 1/05/05 1. 25 4 1/18/06 1.18 5 11/24/06 2. 42 1 1/09/08 Computed Peaks Developed Basin to Pond 2:00 1. 25 8:00 1.18 16:00 0.751 4:00 0.647 6:00 0.331 2.06 Allowable Release Rates Q2 = 0.75 cfs Q10 = 1.31 cfs 4 5.00 5 3.00 6 2.00 7 1. 30 8 1.10 50.00 0.800 0. 667 0.500 0.231 0.091 0.980 The ground cover conditions for the lots in the developed conditions have been calculated with R-4 zoning which has a maximum of 55% impervious area. Total lot area is 11.49 acres. Additional areas include open space, frontage along 148'h A venue SE and the detention tract. The following table shows the breakdown of the developed site areas. Lots Open Space ROW ROW (148th Avenue SE, Offsite) Detention (Open Water) Total Pervious 4.48 acres 0.25 acres 0.86 acres 5.59 acres Total Developed Area to pond KCRTS Peak Developed Flows Flow Frequency Analysis Time Series File:dev.tsf Project Location:Sea-Tac Impervious 5.86 acres 2.91 acres 0.93 acres 0.37 acres 10.07 acres 15.66 acres ---Annual Peak Flow Rates--------Flow Frequency Analysis------- Flow Rate Rank (CFS) 2. 94 6 2. 41 8 3.54 3 2.61 7 3.14 4 3.12 5 3.80 2 5. 94 1 Computed Peaks Job #01-047 August 7, 2008 Time of Peak 2/09/01 2:00 1/05/02 16:00 2/27/03 7:00 8/26/04 2:00 10/28/04 16:00 1/18/06 16:00 10/26/06 0:00 1/09/08 6:00 --Peaks Rank Return Prob (CFS) Period 5.94 1 100.00 0.990 3.80 2 25.00 0.960 3.54 3 10.00 0.900 3.14 4 5.00 0.800 3.12 5 3.00 0. 667 2.94 6 2.00 0.500 2.61 7 1. 30 0.231 2. 41 8 1.10 0. 091 5.23 50.00 0. 980 Page 4-3 East Renton/Rosemonte -Technical Information Report Bypass Area A bypass area of2.21 acres is shown in the Developed Conditions Exhibit; most of this area is recharging the wetlands located in the western portion of the site, see Section 6.3 Wetland Recharge for further information. This area includes a portion of the detention pond, Lots 50-58, Lot 75, and Open Space Tracts Hand K. The following table shows the breakdown of the bypass site areas. Lots/ Open Space KCRTS Peak Bypass Flows Pervious 1.75 acres Impervious Total 0.46 acres 2.21 acres Flow Frequency Analysis Time Series File:bypass.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--------Flow Frequency Analysis------- Flow Rate Rank Time of Peak --Peaks Rank Return Prob (CFS} (CFS} Period 0. 268 4 2/09/01 2:00 0.588 1 100.00 0.990 0.178 7 1/05/02 16:00 0.331 2 25.00 0.960 0.331 2 2/27/03 7:00 0.280 3 10.00 0.900 0.147 8 8/26/04 2:00 0.268 4 5.00 0.800 0.188 6 10/28/04 16:00 0.258 5 3.00 0.667 0.280 3 1/18/06 16:00 0.188 6 2.00 0.500 0.258 5 11/24/06 3:00 0.178 7 1.30 0.231 0.588 1 1/09/08 6:00 0.147 8 1.10 0.091 Computed Peaks O. 502 50. 00 0. 980 The bypass area is added to the detention pond outflow to meet the discharge requirements at the point of compliance downstream of the pond. Facility Output The resulting summary of the Pond is shown below. Refer to the complete printout of the KCRTS summary at the end of this section. Retention/Detention Facility Type of Facility: Side Slope: Pond Bottom Length: Pond Bottom Width: Pond Bottom Area: Top Area at 1 ft. FB: Effective Storage Depth: Stage O Elevation: Storage Volume: Riser Head: Riser Diameter: Job #01-047 August 7, 2008 Detention Pond 3.00 H:lV 200.00 ft 86.00 ft 17200. sq. ft 27727. sq. ft 0.637 acres 4.50 ft 0.00 ft 95868. cu. ft 2.201 ac-ft 4.50 ft 18.00 inches Page 4-4 East Renton/Rosemonte -Technical Information Report Number of orifices: 2 Full Head Pipe Orifice # Height Diameter Discharge Diameter (ft) (in) (CFS) (in) 1 0.00 3.63 0.758 2 2.82 3.25 0. 371 6.0 Top Notch Weir: None Outflow Rating Curve: None Flow Frequency Analysis Time Series File:poc.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--------Flow Frequency Analysis------- Flow Rate Rank Time of Peak -Peaks Rank Return Prob (CFS) (CFS) Period 1. 99 2 2/09/01 19:00 4.23 1 100.00 0.990 0. 567 7 1/06/02 3:00 1. 99 2 25.00 0. 960 1.10 5 2/28/03 4:00 1.30 3 10.00 0.900 0. 4 90 8 8/23/04 23:00 1. 24 4 5.00 0.800 0.748 6 1/05/05 14:00 1.10 5 3.00 0.667 1. 24 4 1/18/06 21:00 0. 748 6 2.00 0.500 1. 30 3 11/24/06 4:00 0.567 7 1. 30 0.231 4.23 1 1/09/08 10:00 0. 490 8 1.10 0.091 Computed Peaks 3. 48 50.00 0. 980 Note that the POC peak values for the 2-and I 0-year storm events (0. 75 cfs and 1.30 cfs accordingly) match or are less than the existing peak flows rates (0.75 cfs and 1.31 cfs). The required detention volume for the pond is 95,868 cf. The volume provided is I 05,292 cf with a design water surface elevation of 453.00 feet and a total live storage depth of 4.50 feet. The provided volume contains a 9.8% safety factor. Control Structure Required Volume= 95,868 cubic feet Provided Volume= 105,292 cubic feet The control structure has 2 orifices on an 18 inch diameter riser. The first orifice is 3 5/8 inches in diameter and is located at the bottom of the riser. The second orifice is 3 1/4 inches in diameter and is located 2.82 feet above the live/dead elevation. Overflow Riser In the event that the orifices plug, the control structure has an overflow riser as a back-up device to ensure the pond discharge direction is controlled. The riser is designed to have enough freeboard above it to pass safely the developed undetained I 00-year peak flow of 5.94 cfs. The riser has been analyzed as a weir using the equation from 5.3.5.H of the Job #01-047 August 7, 2008 Page 4-5 East Renton/Rosemonte -Technical Information Report KCSWDM and the KC Riser Inflow Curve sheet is at the end of this section. A graphical representation of the equation has been shown below. Transition ,.,, ,j ,', ,,,.·)';i~]>\)t-t'-::: > ··:,• H 4.00 • , ,!,, •'.,"''":~..:'-'"~;:.;.1.,. __ '' '''t / .t : .. . . "'·r~ ·r\.J ,._j. t, 3.50 ''?·~~r-;•inl • ,., 11t. ,,.'.,l .1-"' V :; '( ; > ·, · .. · _' r:~?; ~'.~t : '.·'. ·;: ~ 3.00 / I • .. ~ ... J(t:~.t't 1,-f 250 I ' ·' '.,' •, o, fice IC' ..• ; , . ., .. .,, . .,. ff 2.00 :!! V Input Output 1.50 .ff (7 Wei Q (cfs) 5.94 5.94 1.00 . 1,¢-" D (In) 18 18.00 0.50 H (ft) 0.55 " 0.00 Flow: Weir Flow 0 10 20 30 40 50 60 70 BO 90 100 110 120 Diameter (in) 130 From the Overflow Riser calculations, the height of water over the riser is 0.55 feet. A 18 inch riser is provided with 0.60 feet of head to pass the 100-year storm event of 5.94 cfs. Available freeboard is 0.60 feet (453.60-453.00). Jailhouse A jailhouse entrance into the control structure is provided in the event that the inlet pipe becomes obstructed. The jailhouse is sized according to equation 5-6 of the 1998 KCSWDM using the I 00-year developed flow. Q = C(L-0.2H)HY, Q L = --i; + 0.2H CH" Where: Q = I 00-year developed flow 5.94(cfs) C = 3.27 + 0.4 HIP (ft), P =5.6 H = head above weir (ft)-+ 0.7 feet (assumed) L = length (ft) of portion of riser circumference D = inside riser diameter (ft) Job #01-047 August7,2008 L = 5 ·94 Y, + 0.2(0.7) = 3.20 feet+ 12 bars@ 5/8" = 3.83' 3.32(0.7) 2 Jailhouse L required = 3.83 feet L provided = 4.00 feet Page 4-6 East Renton/Rosemonte -Technical Information Report Overflow Spillway Calculations An emergency overflow spillway is provided in the event that the overflow structure becomes obstructed. The spillway is sized according to equation 5-1 of the 1998 KCSWDM using the 100-year developed flow. The spillway is to be 8 feet wide, bottom is set at 453.60 (0.60' above the design water surface), the height is set at 0.40' (454.00 -453.60) and paved with side slopes of 10 percent. Equation 5-1, Section 5.3.1.2 of the 1998 KCSWDM: Q100 = C(2g)Yi[iLHY, + I~ (TanB)HY,] Where: Q100 = Peak flow for the I 00-yr runoff event ( cfs) C = Discharge coefficient (0.60) g = Gravity (32.2 ft/sec 2) L = Length of Weir Q100= C= g= L= H= H = Height of water over weir (ft) --> 0.4 min TANB= Angle of side slopes TAN0= Emergency Overflow Spillway L required= 7.26 feet L provided = 8.00 feet Water Quality Facility Sizing (Pond) 5.94 0.6 32.2 0.4 10 The basic wet pond volume is sized per Chapter 6.4 of the 1998 KCSWDM. The wet pond will utilize dead storage for water quality treatment. The wet-pool volume (Vb) is calculated from finding the volume of runoff (V ,) from the mean annual storm and multiplying it by a wet-pool volume factor (j) of 3.0. V, = (0.9A; + 0.25A1g + O.IOA,r+ O.O!Ao) • R • 43560 (Equation 6-13) where V, = volume of runoff from mean annual storm (cf) A;= area of impervious surface (6.32 acres) A,g= area of till soil covered with grass (3.74 acres) A,r= area of till soil covered with forest (acres) Ao = area of outwash soil covered with grass or forest (acres) R = rainfall from mean annual storm (0.039 feet) [Figure 6.4.1.A] V, = (0.9(10.07) + 0.25(5.59)) • 0.039 • 43560 = 17,771 cf vb~ (17,771)(3) = 53,312 cf Job #01-047 August 7, 2008 Required Water Quality Volume= 53,312 cubic feet Provided Water Quality Volume= 59,267 cubic feet Page 4-7 SECDON 3.2 RUNOFF COMPUTATION AND ANALYSIS ME'Ill0DS FIGURE 3.2.2.A RAINFALL REGIONS AND REGIONAL SCALE FACTORS ST 1.1 ST1.1 ST 1.0 Rainfall Regions and Regional Scale !Factors e'Ll Incorporated Area -e:s River/Lake Major Road 9/1/98 1998 Surface Water Design Manual 3-22 ( ! ( '~ ....... ,. 0 •·. I • .. . .. . . . \) • . : .:,J I.. w,_,.. : . . .... S~TEtCW .... -·, i' I I I =e=-~--;.,,..-1 I I I I I .......... : I I I I I I I I I I .. . . ,. ' ' ' • ·' A1C . '• .. : . --i-.;1 : . ' • ~: AcC 9! 14 .:··!~ .·~ ... • ... ---·= •• , ·.,; Eve . .;. .. 3.2.2 KCRTS/RUNOFF FILES METHOD~ GENERATING TIME SERIES TABLE J.2.2.D EQUIVALENCE DETIVEEN SCS SO\LTYPES AND KCRTS SOIL TYPES SCS Soil Type scs KCRTS Soll Noles Hydrologlc Soll Group Group Alderwood (AgB, AgC, AgD) ·c Till Arents, Alderwood Material (ArnB, AmC) C Till Arenls, Everett Material (An) 8 Outwash 1 Beauslte (BeC, BeD, Bef) C Till 2 Belllnoham (Bh) D Till 3 Brisco! (Br) D TIii 3 Buddev Bu) D Till 4 Earlmont (Ea) D Till 3 E<l<lewlck (Em C Till 3 Everett EvB, EvC, EvD, EwC) NB Outwash 1 Indianola (lnC, lnA, lnD) A Outwash 1 KilsaDIKPB,KpC,KpD) C TIii Klaus{KsC) C Outwash 1 Nelhon {NeC) A Oulwash 1 Newbern (Nal B Till 3 Nooksack (Nk) c· Till 3 Norma No) D Till 3 Orcas Or) D Welland Oridia {Os) D Till 3 Ovaff (OvC, OvD, OvF) C Till 2 I I ('J Pllchuck {Pc) C Till 3 P....,l{Pu) D Till 3 Pwallup (Py} B Till 3 Raanar RaC,RaD,RaC,RaE) B Outwash 1 Renton Rel D Till 3 Salal (Sal C Till 3 Sammamish (Sh) D TIii 3 Seattle(Sk) D Wetland Shalcar (Sm) D Till 3 Si (Sn) C TIii 3 Snohomish (So, Sr) D nu 3 Sultan Sul C TIii 3 Tukwila (TUI D Till 3 Woodinville (Wo) D Till 3 Notes: 1 . Where outwash soils are saturated or underlain at shallow depth (<5 feet) by glacial till, they should be treated as till soils. 2. These are bedrock soils, but calibration of HSPF by King County DNA shows bedrock soils to have similar hydrologlc response to 1111 soils. 3. These are alluvial soils, some of which are underlain by glacial 1111 or have a seasonally high waler table. In the absence of detailed study, these soils should be treated as till soils. 4. Buckley soils are formed on the low-permeability Osceola mudflow. Hydrologic response Is assumed to be similar to that of 1111 soils. 1998 Surface Wa1er Design Manual 911198 GUIDE TO MAPPING UNITS foT.a.ful1 description of a mapping unit, read both the description of the mapping mit and that of the soil series to which the mapping unit belongs. See table 6, page 70, for descriptions of woodland groups. Other ,ncJtion is given in table~ as follows: ( / (~~) Acreage and extent, table 1, page 9. Engineering uses of the soils, tables 2 and 3, pages 36 through SS. Town and country planning, table 4, page 57. Recreational uses, table S, page 64. Estimated Yields, table 7, page 79. Map syri>ol Mapping unit "gB-AJderwood gravelly sandy loam, O to 6 percent slopes---------- "aC-AJder,,ood gravelly sandy loa.JJt, 6 to JS percent slopes--------- 'aD AJdentood gravelly sandy 10am, 15 to 30 percent slopes-------- ~f Alderwood and Kitsap soiJs, very steep------------------------ timB Arents, Alde:rwood material, O to 6 percent slopes 1/---------- '1,C Arents, Alderwood material, 6 to 15 percent slopes-1/--------- '" Arents Everett material 1/------------------------=----------- JeC B"eawi;e gravelly sandy 10am, 6 to 15 pe~cent slopes---------- JeD Beausi te rravelly sandy loam, JS to 30 percent slopes--------- lef Baawite iravelly sandy loam, 40 to 75 .percent sJopes--------- lh BeJltnet,aa silt loa11------------------------------------------ 1r Briscot silt loml--------------------------------------------- lu Buc~ley silt loa:D--------------------------------------------- h Co&S tel beaches-·--------------------------------------------- :a EarlDOnt sl·lt loUl-------------------------------------------- 'cl Edgewick fine sandy Jomo-------------------------------------- !vB Everett 1rave1Jy sandy loam, O to 5 percent slopes------------ :VC Everett cravelly sandy loaJD, 5 to 15 percent slopes----------- :vo Everett 1ravelly sandy loalll, JS to 30 percent slopes---------- WC 'Everett-Aldnwood ,ravel ly sandy loam.s, 6 to IS percent s J opes------------------------------------------------------ nA Indianola Joany fine sand, Oto 4 percent slc,pes-------------- nC" ~'!di anola loamy fine sand, 4 to IS percent s)opes--------------.. i 1di anola loany fine sand, IS to 30 percent slopes------------ ~ ,"itsap silt loasca, 2 to 8 percent slopes----------------------- /'-·_.f.Xitsap silt loam, 8 to JS percent s)opes---------------------- ~--'Kitsap silt 10111, JS to JO percent slopes--------------------- sC klaus ,rave])y loamy sand, 6 to JS percent slopes------------· D Mixed alluvial Jand-------------------------------------·----- aC Neil ton very craveJJy loamy sand, 2 to 15 percent slopes-----· I Newbera silt loao---------------·------·----------------------llooksock silt Jom>-------------------------------------------- :, Noma sandy Joa---------------------------------------------- r Orcns peat------------·-----------------------------• --------· , Orldia silt lolJlt---------------------------------------------· ,c Ovall gravelly Joan, Oto JS percent slopes------------------· ,D Ovall eravellr Jom, JS to 2S percent slopes------------------ rf Oval] eravellr )01111, 40 to 7S percent slopes------------------ Plldiuck 10111111 fine sand--• -----• ------• --------• --• -• -------• Pilchuct fine sandy loam-------------------------------------· Puaet silty clay Joam-------------------------·--------------- Puya llup fl ne sandy J omn------------------------• • --• • ---·---• Described on page IO 8 JO 10 10 JO II JI 12 12 12 13 13 14 14 JS JS 16 16 ,c P..a,nar fine sandy tom, 6 to 15 percent slopes---------------- 1.D Raenar fine sU1dy loDIII, 15 to 2S percent slopes--------------- lC Ragnar-Indianola association, slopine: 1/·-------------------:.. R•sn•r·,011--------------------------------------------- Jndlm,ola soil------------------------------------------· 16 17 )6 J7 J7 18 18 .)8 18 19 19 20 20 21 21 22 23 23 23 23 24 24 25 26 26 IE Ragnar-Indianola association, 1110derately steep: Y-------·--·· Rasnar soll---------------------------------------------- Jndianola sol I-----------------------------------------• • 26 Woodland Capability unit group Synool Page SyDi>ol !Ve-2 76 3d2 IVo-2 76 3d) Vlo-2 78 3d) Vile-I 78 2d) IVe-2 76 3d2 IVe-2 76 3d2 IVs-I 77 3f3 IVe-2 76 3d2. Vlo-2 78 3d) Vile-I 78 3d) JIJw-2 76 3"2 llw-2 75 3w) 1-1 Jw-2 76 · 4wl Vlllw-1 78 llw-2 75 3"2 lllw-1 75 2ol IVs-I 77 3f3 Vis-I 78 3f3 Vle-1 77 3f2 Yls-1 78 3f3 IVs-2 77 4s3 IYs-2 77 4s3 Vle-1 76 4s2 II Je-1 75 2d2 IVe-1 76 1d2 Vle-2 78 2d) Vis-I 78 3fJ Vlw-2 78 2ol Vis-I 78 3f3 IJw-1 74 2ol llw-1 74 2ol I llw-3 76 3w2 VJllw-1 78 llw-2 75 3Wl IVe-2 76 3d) Vle-2 78 3d) Vile-I 78 3d) Vlw-1 78 2,1 J'llf-1 76 2,1 lllw-2 76 3w2 llw-1 74 2ol IVo-3 77 4sl Vlo-2 78 4sJ ·---·--- !Vo-3 77 4sJ !Vs-2 77 4s3 ----·--- Vle-2 78 4sl Vie-I 77 452 u. "· C0VERNMEH1' PREPfTINC orFIC'!: u,, O. 01-IH Retention/Detention Facility Type of Facility: Detention Pond Side Slope: 3.00 H: lV Pond Bottom Length: 200.00 ft Pond Bottom Width: 86.00 ft Pond Bottom Area: 17200. sq. ft Top Area at 1 ft. FB: 27727. sq. ft 0.637 acres Effective Storage Depth: 4.50 ft Stage O Elevation: 0.00 ft Storage Volume: 95868. cu. ft 2.201 ac-ft Riser Head: 4.50 ft Riser Diameter: 18.00 inches Number of orifices: 2 Full Head Pipe Orifice # Height (ft) 0.00 2.82 Diameter (in) 3.63 3.25 Discharge (CFS) Diameter (in) 1 2 Top Notch Weir: None Outflow Rating Curve: None 0. 7 58 0.371 6.0 Stage Elevation Storage Discharge (ft) (ft) (cu. ft) (ac-ft) (cfs) 0.00 0.00 0. 0.000 0.000 0.04 0.04 68 9. 0.016 0.070 0.08 0.08 1382. 0.032 0.098 0.11 0.11 1902. 0.044 0.120 0.15 0.15 2599. 0.060 0.139 0.19 0.19 3299. 0.076 0.155 0.23 0.23 4002. 0.092 0.170 0.26 0.26 4530. 0.104 0.184 0.30 0.30 5238. 0.120 0. 197 0.40 0.40 7018. 0.161 0.227 0.50 0.50 8816. 0.202 0.253 0. 60 0.60 10631. 0.244 0.277 0.70 0.70 12465. 0.286 0.300 0.80 0. 80 14315. 0.329 0.320 0.90 0.90 16184. 0. 372 0. 34 0 1. 00 1. 00 18070. 0.415 0.358 1.10 1.10 19974. 0. 459 0.375 1. 20 1. 20 21896. 0.503 0.392 1. 30 1. 30 23836. 0.547 0. 4 08 1. 40 1. 4 0 25795. 0. 592 0.423 1. 50 1. 50 27771. 0.638 0. 4 38 1. 60 1. 60 29766. 0.683 0. 452 1. 70 1. 70 31779. 0.730 0.466 1. 80 1. 80 33810. 0.776 0.480 1. 90 1. 90 35860. 0.823 0.493 2.00 2.00 37928. 0.871 0.506 2.10 2.10 40015. 0.919 0.518 2.20 2.20 42120. 0. 967 0.530 2.30 2.30 44245. 1. 016 0.542 2.40 2. 4 0 46388. 1. 065 0.554 2.50 2.50 48550. 1.115 0.565 2. 60 2.60 507 31. 1.165 0. 577 Percolation (cfs) 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Surf Area (sq. ft) 17200. 17269. 17 338. 17389. 17458. 17527. 17597. 17 64 9. 17718. 17892. 18067. 18243. 18419. 18596. 18774. 18952. 19131. 19311. 194 92. 19673. 19855. 20038. 20221. 20405. 20590. 20776. 20962. 21149. 21337. 21526. 21715. 21905. 2.70 2.70 52931. 1. 215 0.588 0.00 22096. 2.80 2.80 55150. 1. 266 0.598 0.00 22287. 2.82 2.82 55596. 1. 276 0.600 0.00 22325. 2.85 2.85 56267. 1. 292 0. 606 0.00 22383. 2.89 2.89 57164. 1. 312 0.618 0.00 22460. 2. 92 2.92 57838. 1. 328 0.635 0.00 22518. 2.96 2. 96 58741. 1. 34 9 0.656 0.00 22595. 2.99 2.99 59419. 1. 364 0. 683 0.00 22653. 3.02 3.02 60100. 1. 380 0. 714 0.00 22711. 3.06 3.06 61010. 1. 401 0.747 0.00 22788. 3.09 3.09 61694. 1. 416 0. 777 0.00 22846. 3.19 3 .19 63989. 1. 4 69 0. 813 0.00 23040. 3.29 3.29 66302. 1. 522 0.845 0.00 23235. 3.39 3.39 68636. 1. 576 0.875 0.00 23431. 3.49 3. 4 9 70989. 1. 630 0.902 0.00 23627. 3.59 3.59 73361. 1. 684 0.929 0.00 23824. 3.69 3.69 75754. 1.739 0.954 0.00 24022. 3. 79 3.79 78166. 1. 794 0. 978 0.00 24221. 3.89 3.89 80598. 1. 850 1.000 0.00 24420. 3.99 3.99 83050. 1. 907 1.020 0.00 24620. 4.09 4.09 85522. 1. 963 1.050 0.00 24821. 4.19 4.19 88014. 2.021 1. 070 0.00 25022. 4.29 4.29 90526. 2.078 1. 090 0.00 25224. 4.39 4.39 93059. 2 .136 1.110 0.00 25427. 4.49 4.49 95612. 2.195 1.130 0.00 25631. 4.50 4.50 958 68. 2.201 1.130 0.00 25651. 4.60 4. 60 984 4 3. 2.260 1. 610 0.00 25855. 4.70 4.70 101039. 2.320 2.470 0.00 26060. 4.80 4.80 103655. 2.380 3.590 0.00 26266. 4.90 4. 90 106292. 2.440 4.900 0.00 26473. 5.00 5.00 108950. 2.501 6.390 0.00 26680. 5.10 5.10 111628. 2.563 7.830 0.00 26888. 5.20 5.20 114328. 2. 625 8.380 0.00 27097. 5.30 5.30 117048. 2.687 8.890 0.00 27306. 5.40 5. 40 119789. 2.750 9.360 0.00 27516. 5.50 5.50 122551. 2.813 9.820 0.00 27727. 5.60 5.60 125334. 2.877 10.250 0.00 27939. 5.70 5. 70 128139. 2.942 10.660 0.00 28151. 5.80 5.80 130964. 3.007 11. 060 0.00 28364. 5.90 5.90 133812. 3. 072 11.440 0.00 28578. 6.00 6.00 136680. 3.138 11.810 0.00 287 92. 6.10 6.10 139570. 3.204 12.170 0.00 29007. 6.20 6.20 142481. 3. 271 12.510 0.00 29223. 6.30 6.30 145415. 3.338 12.850 0.00 29440. 6.40 6. 4 0 148369. 3.406 13 .180 0.00 29657. 6.50 6.50 151346. 3.474 13. 500 0.00 29875. Hyd Inflow Outflow Peak Storage Stage Elev (Cu-Ft) (Ac-Ft) 1 5.94 4.03 4.83 4.83 104538. 2.400 2 2.94 1. 81 4.62 4. 62 99059. 2.274 3 3.80 1.13 4.50 4.50 95848. 2.200 4 3.12 1. 08 4.24 4.24 89392. 2.052 5 3.54 0. 97 3.77 3. 77 77580. 1. 781 6 3.14 0.66 2. 97 2. 97 58871. 1.351 ) 7 2.41 0. 4 9 1. 87 1. 87 35172. 0.807 8 2.61 0. 4 6 1. 66 1. 66 31057. 0. 713 Hyd R/0 Facility Tributary Reservoir POC Outflow Outflow Inflow Inflow Target Cale 1 4.03 0.59 ******** **"'**** 4.17 * ) 2 1. 81 0. 27 ****"**** 3 1.13 0.26 ******** 4 1. 08 0.28 ******** 5 0. 97 0.33 ******** 6 0.66 0 .19 ******** 7 0. 4 9 0.18 ******** 8 0. 4 6 0.15 ******** R/D Facility lagged: 0.50 hours ---------------------------------- Route Time Series through Facility Inflow Time Series File:dev.tsf Outflow Time Series File:pondout POC Time Series File:poc Inflow/Outflow Analysis Peak Inflow Discharge: 5. 94 Peak Outflow Discharge: 4.03 Peak Reservoir Stage: 4.83 Peak Reservoir Elev: 4.83 CFS CFS Ft Ft "**·!<**** 1. 31 ******* ******* 0. 75 ******* ******* at 6:00 at 10:00 Peak Reservoir Storage: 104538. Cu-Ft 2. 400 Ac-Ft Add Time Series:bypass.tsf 1. 94 * 1. 23 * 1.18 * 1. 06 * 0.74 * 0.55 * 0.47 * on Jan 9 in Year 8 on Jan 9 in Year 8 Peak Summed Discharge: 4.23 CFS at 10:00 on Jan 9 in Year 8 Point of Compliance File:poc.tsf Flow Frequency Analysis Time Series File:pondout.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--------Flow Frequency Analysis------- Flow Rate Rank Time of Peak --Peaks --Rank Return Prob (CFS) (CFS) (ft) Period 1. 81 2 2/09/01 19:00 4.03 4.83 1 100.00 0.990 0. 489 7 12/28/01 17:00 1. 81 4. 62 2 25.00 0. 960 0. 972 5 2/28/03 7:00 1. 13 4.50 3 10.00 0.900 0. 4 61 8 8/24/04 0:00 1. 08 4.24 4 5.00 0. 800 0.661 6 1/05/05 14:00 0. 972 3.77 5 3.00 0. 667 1. 08 4 1/18/06 22:00 0.661 2.97 6 2.00 0.500 1.13 3 11/24/06 7:00 0. 4 8 9 1. 87 7 1. 30 0.231 4.03 1 1/09/08 10:00 0. 4 61 1. 66 8 1.10 0.091 Computed Peaks 3. 2 9 4.77 50.00 0.980 Flow Frequency Analysis Time Series File:poc.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--------Flow Frequency Analysis------- Flow Rate Rank Time of Peak -Peaks Rank Return Prob (CFS) (CFS) Period 1. 99 2 2/09/01 19:00 4.23 1 100.00 0.990 0.567 7 1/06/02 3:00 1.99 2 25.00 0. 960 1.10 5 2/28/03 4:00 1.30 3 10.00 0.900 0. 4 90 8 8/23/04 23:00 1.24 4 5.00 0.800 0.748 6 1/05/05 14:00 1.10 5 3.00 0.667 1. 24 4 1/18/06 21:00 0.748 6 2.00 0.500 1. 30 3 11/24/06 4:00 0.567 7 1. 30 0.231 4.23 1 1/09/08 10:00 0. 490 8 1.10 0.091 Computed Peaks 3.48 50.00 0.980 6.4.1 WBTPONDS -BASIC AND LA.RGB-MKTHODS OF ANALYSIS FIGURE 6,4,J,A PRECIPlTA TION FOR MEAN ANNUAL STORM IN INCHES (FEET) ! . ' 0.54· (0.045') ( -:-: Jnootpallltod AIOO ....c,Q --MojorRoad 0.47" (0.039') 0,47• (0 . .039') NOTO: Ania• oaal of tho 0001ommoa1 looplUVlol aho\11<1 uao o.ea lnolloa unloaa mlnf!ID dota lo ovalloble lor lho looallon ol lllloreat N lho moan tnnUd ctonn II a ciano:,ptuo,l ttonn found by cHOlg: Cho tM&:t PNrAllltlliot by lho total f'IMQI oi IIIOffl'I ovontl por yoar LA, LA 1.0 LA 1.2 0 , 9 •••t.•~• ,·.w•u Q .... ~--.. () (0.047') result, generates large amounl.l of runoff. For this application, till soil types Include Buckley and bedrock solls, and alluvial and outwash soils that have a seasonally high water table or are underlain at a shallow depth (lea than S feet) by glacial tlll. U.S. Soll Conservation Service (SCS) hydrologlc soll groups that are clasalfled as 1111 soils lntlude a few B, most C, and all D soils. See Chap1er 3 for classlflcatlon of speclf1c SCS soil types. 1998 Surface Water Do,lgn Manual 9/1/98 6°69 Pond Volume Calculation Table East Renton I Rosemonte 10APR 08 Live Storage Stage Area Average Area Volume (ft) (square feet) (square feet) (cubic feet) DWS 453.00 28,855 452.00 26,350 27,603 27,603 450.00 21,588 23,969 47,938 UD 448.50 18,080 19,834 29,751 Total 105,292 D dS Cll1 ea torage e Stage Area Average Area Volume (ft) (sauare feet) (square feet) (cubic feet) UD 448.50 6.423 448.00 6.139 6,281 3,141 446.00 4,008 5,074 10,147 444.00 2.422 3,215 6,430 top of sed. Storage 443.50 2,090 2,256 1,128 442.50 1,425 Total 20,845 Dead Storage Cell 2 Stage Area Average Area Volume (ft) (square feet) (square feet) (cubic feet) UD 448.50 11,657 448.00 10,812 11,235 5,617 446.00 7 465 9,139 18,277 444.00 4,800 6,133 12,265 too of sed. Storaae 443.50 4,251 4,526 2,263 443.00 Total 38,422 Required Provided % extra Live 95,868 105,292 9.83 Dead 53,312 59,267 11.17 Cell 1 % of total 25 to 35 35 East Renton/Rosemonte -Technical Information Report 5 CONVEYANCE SYSTEM ANALYSIS & DESIGN Core Requirement No. 4 of the 1998 KCSWDM requires onsite conveyance systems to be designed to pass peak flows generated from the 25-year storm event. All pipes and curb sections associated with the development convey the 100-year peak flow rate as to not create or aggravate a severe flooding problem onsite. Backwater analysis was performed using the King County Backwater (KCBW) program. The conveyance system consists of curb and gutter road sections with catch basins collecting runoff into tight-lined drainage systems. Roof, yard, rockery and footing drains will also be connected to the tight-lined system. 5.1 Conveyance Concept and Methodology The onsite and offsite conveyance systems will be analyzed using the KCBW program. Refer to the Catch Basin Tributary Area Exhibit and KCBW print out reports located at the end of this section to aid in the following discussion. The conveyance system has been designed in accordance with the 1998 King County Surface Water Design Manual (KCSWDM) to provide sufficient capacity to convey and contain, at minimum, the 25-year peak flow assuming developed conditions for onsite tributary areas and existing conditions for any offsite tributary areas. The system has been analyzed during the 100-year design storm event to show that overtopping will not create or aggravate a "severe flooding problem" or "severe erosion problem". The King County Back Water program is used to calculate the hydraulic grade line at each catch basin. The KCBW program sums the flows tributary to each reach (pipe) and then performs a standard step backwater analysis on the network. The steady state energy equation (Bernoulli's equation) is used along each reach in the network. The friction slope is calculated by averaging Manning's equation at the upstream and downstream ends of the pipe. The hydraulic grade line is calculated from downstream to upstream. Job#01-047 August 7, 2008 Page 5-8 East Renton/Rosemonte -Technical Information Report 5.2 Flow using the Rational Method & KCRTS-15 minute Time steps All flows with areas less than 10 acres were obtained using the rational method and were analyzed using the KCBW program for conveyance analysis. Catch Basin 4 incorporates I 0 acres of the site and, therefore, is a transition point for the methodology used to determine catch basin tributary flows. Areas tributary to the conveyance system downstream of Catch Basin 4 will use KCRTS with 15-minute time step. The analysis begins at the upstream point of the conveyance system until IO tributary acres are accounted for. Estimated flows for the I 00-year, 24-hour storm is calculated using the rational method as described in Section 3.2.1 of the KCSWDM and is summarized below. Fundamentally, the Modified Rational Method equation is QR= peak flow (cfs) for a storm of return frequency R C = estimated runoff coefficient (ratio of rainfall that becomes runoff) IR = peak rainfall intensity A = drainage sub-basin area (acres) This method requires tributary delineation for each catch basin. Each tributary area was obtained by reviewing finish grade contours and the proposed conveyance system. The runoff coefficient for each tributary was weighted individually within the system using the equation shown below (Section 3.2.1 KCSWDM). When two branches of a system meet, the longest travel time of the two branches was selected and utilized along the downstream system and the runoff coefficients for each run are weighted. Cc= C1A1 + C2A2 + ... CnAn)/A, where A, = total area (acres) A1,2, .. ·n = areas of land cover types (acres) C 1,2, ... n = runoff coefficients for each area land cover type Cgrass = 0.25 C;mpervious = 0.90 Cjorest = 0 .15 Total Grass area to pond= 5.59 acres Total Impervious area to pond = 10.07 acres Job #01-047 August7,2008 C . 5.59(0.25) + 10.07(0.90) _ 0 68 weighted J S. 66 -· Page 5-9 East Renton/Rosemonte -Technical Information Report Each catch basin area is delineated and applied a constant flow per acre for that basin for areas greater than IO acres. The total amount of impervious and pervious area being collected in the conveyance system is determined by using the developed conditions from Section 4. The peak flow is calculated using the KCRTS program with 15-minute time steps. Parameters used for the analysis were SeaTac Rainfall Region and Scale Factor of 1.0. The I 00-year KCTRS 15-minute time step flow rate. Flow Frequency Analysis Time Series File:15mindev.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--------Flow Frequency Analysis------- Flow Rate Rank Time of Peak --Peaks Rank Return (CFS) (CFS) Period 4.79 6 8/27/01 18:00 14.70 l 100.00 3. 40 8 1/05/02 15:00 10.28 2 25.00 10.28 2 12/08/02 17:15 6.69 3 10.00 3.86 7 8/23/04 14 :30 5.85 4 5.00 5. 85 . 4 11/17 /04 5:00 5. 73 5 3.00 5.73 5 10/27 /05 10: 45 4.79 6 2.00 6.69 3 10/25/06 22:45 3. 86 7 1. 30 14.70 1 1/09/08 6:30 3. 40 8 1.10 Computed Peaks 13.23 50.00 The following is the flow per acre calculation for the I 00 year storm event. Job #01-047 August 7, 2008 Flow per acre, Q100 14 ·70 = 0.93 cfs/acre 15.77 Prob 0.990 o. 960 0.900 0.800 0.667 0.500 0.231 0. 091 0. 980 Page 5-10 CB I Area lac\ 3 0.26 4A 0.59 4 0.12 5 0.35 6A 0.44 6B 0.18 6 0.09 7A 0.07 7 0.00 8 0.81 9 0.08 10 0.23 11 0.04 12 0.08 13A 0.31 13 0.10 14A 0.56 14 0.18 15 0.03 16A 0.81 16 0.15 17A 0.08 17 0.94 18 0.00 19A 0.50 19 0.08 20A 0.43 20 0.08 21A 0.25 Job #01-047 August 7, 2008 East Renton/Rosemonte -Technical Information Report Runoff Computations Spreadsheet and Q ratios Flow lcfsl Flow lcfsl Additional I Sum Q ratio CB T Area Addltlonal I Sum Q lac) ratio 0.24 11.78 0.021 21 0.13 0.27 2.11 0.615 0.55 22 0.59 1.24 1.31 20.308 0.11 11.54 23 0.03 0.06 0.06 0.53 14.45 0.038 24A 0.09 0.20 0.20 0.69 24 0.10 0.21 0.41 1.016 0.29 25A 0.16 0.25 0.14 13.92 0.087 25 0.04 0.07 7.06 0.046 0.11 26 0.03 0.05 6.99 0.008 0.00 12.80 0.009 27 0.66 1.08 6.94 0.185 1.28 12.69 0.112 28 0.30 0.49 5.85 0.092 0.13 11.41 0.012 29 0.00 0.00 5.36 0.043 0.38 11.28 1.473 30A 0.49 0.96 0.06 4.56 0.014 30 0.45 0.83 5.14 0.534 0.14 4.50 0.033 31A 0.57 1.21 0.57 31 0.57 1.11 3.35 2.243 0.18 4.36 0.210 32 0.00 0.00 1.03 0.000 1.13 33 0.02 0.04 1.03 0.044 0.34 3.60 0.687 34 0.03 0.07 0.99 0.072 0.06 2.13 0.029 35 0.43 0.92 0.92 1.76 1.76 36 0.05 0.11 0.22 0.991 0.31 2.07 0.177 37 0.05 0.11 0.11 0.14 38 0.20 0.22 1.29 0.204 1.58 6.34 0.372 39 0.10 0.13 1.07 0.140 0.00 4.62 0.098 40 0.11 0.15 0.94 0.193 0.93 41 0.09 0.13 0.79 0.193 0.14 4.21 0.341 42 0.13 0.21 0.66 0.472 0.88 43 0.12 0.22 0.45 0.929 0.16 3.14 0.490 44 0.11 0.23 0.23 0.53 Page 5-11 East Renton/Rosemonte -Technical Information Report Freeboard Tables The following tables provide total system flows, ground elevations, HGL elevations, and the amount of freeboard in each catch basin structure. Refer to the KCBW Outputs at the end of this section for details. All pipe systems will provide capacity to convey the I 00-year peak flow without overtopping. The tailwater elevation used for the system was assumed to be 353.00 (the JOO-year design water surface of the pond). Freeboard Table (100-year design surface) ~ ". · ' . · ' . · ;'. ,t,t~draull~,: , ; ,, · ,,, · '·:~;., ... ··!.,. Ground , . , G---··d· , .. ,_ , ·~-'b', -..:r. l{;iibe( "El vi.ff ., . ., ,,: . ra !!•.<,•, !r,ree. oa,~'; ,c,' ';, .. & Oll; [,•l!Jne',ln ,1 ({>C f(ft)!'.f.' '.: . . : · . ,(ft) ' ' ; ,; '. ,(ftf" .'. I f ;; ,, ,~\_:; 1 455.00 453.17 1.83 2 455.00 3 459.00 4 461.10 5 457.60 6 457.22 7 458.57 8 458.29 9 459.02 10 459.52 11 460.89 12 460.89 13 463.21 14 466.06 15 469.48 16 466.39 16A 466.39 17 468.57 18 480.23 19 481.40 20 489.71 21 499.38 22 501.51 Job#01-047 August 7, 2008 453.31 1.69 453.59 5.41 453.69 7.41 454.45 3.15 455.02 2.20 456.01 2.56 457.66 0.63 455.60 3.42 457.23 2.29 458.56 2.33 458.92 1.97 459.47 3.74 461.53 4.53 462.25 7.23 463.09 3.30 463.16 3.23 468.14 0.43 478.68 1.55 479.31 2.09 486.69 3.02 495.70 3.68 495.97 5.54 ;~;\!t;i;)~-',: '.i~J.,tiF 0) ~T ';;_ ' ... . ·-,··., //~~."., .. ·' 23 24 24A 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 ~-:·· _~,'.-·: t' ·:.""'.., r :Hydtaullci • .,.,.,u;-~:~~'J_.?1.ti;J I ,, ~~~n~·~, ./,;, .,_, 1~·'" ,-', .. GhidiL;,.i ~F,?e.;b'oaril~ 'Elev,atlon , : I:ihe1n :: ·',, .... ,:,ft. •11'.~ ,, . ,(~) ' ' . '·•'( ) '•"'' . ., ./ti ... ·.--;: -~;_,.:~_-;~~ '. :. -~ ... _ ' .',_" ft '· ·:-·"' '.\.,.,;. 499.04 495.98 3.06 485.41 482.43 2.98 485.41 482.61 2.80 478.31 473.71 4.60 482.06 477.61 4.45 484.25 480.36 3.89 484.51 484.35 0.16 497.15 495.12 2.03 497.63 496.99 0.64 505.95 503.63 2.32 512.09 507.76 4.33 511.70 507.99 3.71 511.70 508.16 3.54 512.38 508.16 4.22 499.30 496.29 3.01 499.38 496.54 2.84 462.19 457.96 4.23 486.31 483.59 2.72 496.01 493.33 2.68 503.79 500.74 3.05 508.18 505.10 3.08 512.77 509.67 3.10 516.09 511.20 4.89 Page 5-12 .~··· FIGURE 3.2.1.D 100-YEAR 24-HOUR ISO PLUVIALS WIESTERN ~ING COUNTY 1oo~vear 24-Hour Precipitation In Inches 1998 Surface Water Design Manual O 2 4 Miles 3-17 3.2.1 RATIONAL METilOD 9/1/98 Runoff Computations Spreadsheet and Q ratios Area CB sf ac 37 2,227 0.05 36 2,250 0.05 29 0.10 35 18,532 0.43 34 1,346 0.03 33 897 0.02 32 0 0.00 31A 24,681 0.57 31 24,876 0.57 30A 21,386 0.49 30 19,795 0.45 29 0.10 29 0 0.00 26 12,663 0.30 27 28,706 0.66 26 1,466 0.03 25A 6,830 0.16 25 1,885 0.04 4 3.85 24A 4,094 0.09 24 4,225 0.10 18 0.19 23 1,229 0.03 22 25,551 0.59 21A 10,927 0.25 21 5,769 0.13 20A 18,702 0.43 20 3,603 0.08 19A 21,583 0.50 19 3,376 0.08 18 0.19 18 0 0.00 17A 3,481 0.08 17 41,088 0.94 10 3.30 16A 35,358 0.81 16 6,345 0.15 15 1,321 0.03 14A 24,520 0.56 14 8,022 0.18 13A 13,677 0.31 13 4,542 0.10 12 3,645 0.08 11 1,576 0.04 10 3.30 10 9,932 0.23 9 3,557 0.08 8 35,131 0.81 7A 3,010 0.07 7 0 0.00 68 8,000 0.18 SA 19,210 0.44 6 3,901 0.09 5 15,437 0.35 4 7.82 C 0.68 0.68 0.68 0.68 0.68 0.68 0.68 0.68 0.68 0.68 0.68 0.68 0.68 0.68 0.68 0.68 0.68 0.68 0.68 0.68 0.68 0.68 0.68 0.68 0.68 0.68 0.68 0.68 0.68 0.68 0.68 0.68 0.68 0.68 0.68 0.68 0.68 0.68 0.68 0.68 0.68 0.68 0.68 0.68 0.68 0.68 0.68 L 0 35 62 9 28 37 173 143 67 178 26 44 54 238 28 57 43 70 172 160 24 109 95 28 123 204 97 79 28 32 57 72 14 122 58 143 Tc min 0.2 0.1 0.2 0.2 0.0 1.0 0.0 0.8 0.4 1.0 0.2 0.2 0.0 0.3 0.2 0.2 0.0 0.4 0.0 1.0 0.0 0.9 0.1 0.0 0.6 0.2 0.7 0.0 1.1 0.0 0.5 0.4 0.2 0.2 0.3 0.4 0.0 0.1 0.0 0.0 0.7 0.3 min 6.3 6.5 6.5 6.3 6.4 6.5 6.7 6.5 7.5 7.5 8.3 8.6 9.6 9.8 10.0 10.0 10.3 10.3 6.3 6.5 8.5 6.3 6.5 6.5 6.9 6.9 7.9 7.9 8.8 8.9 8.9 9.5 9.5 6.3 6.5 7.1 7.1 8.3 8.3 6.8 9.3 9.4 9.5 9.7 10.0 10.4 10 .. 4 10.5 10.5 10.5 11.2 11.5 ' I 3.19 3.13 3.19 3.18 3.13 3.07 3.13 2.87 2.87 2.69 2.62 2.44 2.42 2.38 2.38 2.34 3.19 3.14 3.19 3.12 3.12 3.01 3.01 2.77 2.77 2.59 2.57 2.57 2.46 3.19 3.14 2.95 2.95 2.69 2.69 2.58 2.51 2.48 2.43 2.39 2.33 2.33 2.32 2.32 2.32 2.23 2.19 Additional 0.11 0.11 0.92 0,07 0.04 0.00 1.21 1.11 0.96 0.83 0.22 0.00 0.49 1.06 0.05 0.25 0.07 0.20 0.21 0.06 1.24 0.53 0.27 0.88 0.16 0.93 0.14 0.41 0.00 0.14 1.58 1.76 0.31 0.06 1.13 0.34 0.57 0.18 0.14 0.06 6.34 0.38 0.13 1.28 0.11 0.00 0.29 0.69 0.14 0.53 Flow(Q) Sum 0.11 0.22 0.22 0.92 0.99 1.03 1.03 3.35 5.14 5.36 5.65 6.94 6.99 7.06 7.06 0.20 0.41 0.41 0.06 1.31 2.11 3.14 4.21 4.62 6.34 6.34 1.76 2.07 2.13 3.60 4.36 4.50 4.56 11.28 11.41 12.69 12.80 13.92 14.45 14.45 Ratio 0.991 · 0.072 0.044 0.000 2.243 0.534 0.043 0.092 0.165 0.006 0.046 1.016 20.308 0.615 0.490 0.341 0.098 0.372 0.177 0.029 0.687 0.210 0.033 0.014 1.473 0.012 0.112 0.009 0.087 0.036 4A 25,802 0.59 0.55 4 7.82 4 3.85 flow/ ac 11.43 4 5,045 0.12 0.93 0. 11 11.54 3 11,174 0.26 0.93 0.24 11.78 0.021 POND 11.78 44 4,651 0. 11 0.68 0 6.3 3.19 0.23 0.23 43 5,099 0.12 0.68 170 1.9 8.2 2.71 0.22 0.45 0.929 42 5,788 0.13 0.68 193 4.0 10.3 2.34 0.21 0.66 0.472 41 3,769 0.09 0.68 125 5.4 11.7 2.16 0.13 0.79 0.193 40 4,913 0.11 0.68 157 7.2 13.5 1.98 0.15 0.94 0.193 39 4,560 0.10 0.68 149 8.8 15.1 1.84 0.13 1.07 0.140 38 8,566 0.20 0.68 290 12.0 18.3 1.63 0.22 1.29 0.204 POND 88 1.29 BACKWATER COMPUTER PROGRAM FOR PIPES Pipe data from file:POND-4.bwp Surcharge condition at intermediate junctions Tailwater Elevation:453. feet Discharge Range:11.78 to 11.78 Step of 1. [cfs] Overflow Elevation:461.1 feet Weir:NONE Upstream Velocity:3. feet/sec PIPE NO. 1: 77 LF -30"CP @ OVERFLOW-EL: 455.00 2.87% OUTLET: 445.00 INLET: 447.21 INTYP: 5 JUNC NO. 1: BEND: 65 DEG DIA/WIDTH: 4.0 Q-RATIO: 0.00 Q(CFS) HW(FT) HW ELEV. * N-FAC. DC DN TW DO DE HWO HWI ******************************************************************************* 11. 7 8 PIPE NO. 2: JUNC NO. 2: 5.96 453.17 * 0.012 1.16 0.67 8.00 8.00 5.85 5.96 1. 59 88 LF -30"CP @ OVERFLOW-EL: 455.00 0.60% OUTLET: 447.21 INLET: 447.74 INTYP: 5 BEND: 35 DEG DIA/WIDTH: 4.0 Q-RATIO: 0.00 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 11. 7 8 5.57 453.31 * 0.012 1.16 1.01 5.96 5.96 5.50 5.57 1. 58 PIPE NO. 3: JUNC NO. 3: 220 LF -30"CP @ OVERFLOW-EL: 459.00 0.60% OUTLET: 447.74 INLET: 449.06 INTYP: 5 BEND: 70 DEG DIA/WIDTH: 4.0 Q-RATIO: 0.02 Q (CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 11. 7 8 4. 53 453.59 * 0.012 1.16 1.01 5.57 5.57 4.41 4.53 1. 63 PIPE NO. 4: 140 LF -30"CP @ 0.60% OUTLET: 449.06 INLET: 449.90 INTYP: 5 Q(CFS) HW (FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 11. 54 3.79 453.69 * 0.012 1.14 1.00 4.53 4.53 3.79 3.78 1. 4 8 BACKWATER COMPUTER PROGRAM FOR PIPES Pipe data from file:4-16A.bwp Surcharge condition at intermediate junctions Tailwater Elevation:453.69 feet Discharge Range:14.45 to 14.45 Step of 1. [cfs] Overflow Elevation:466.39 feet Weir:NONE Upstream Velocity:3. feet/sec PIPE NO. 1: 143 LF -24"CP @ OVERFLOW-EL: 457.60 0.56% OUTLET: 450.40 INLET: 451.20 INTYP: 5 JUNC NO. 1: BEND: 30 DEG DIA/WIDTH: 4.0 Q-RATIO: 0.04 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 14.45 PIPE NO. 2: JUNC NO. 2: 3.25 454.45 * 0.012 1.37 1.34 3.29 3.29 2.99 3.25 1. 96 58 LF -24"CP @ OVERFLOW-EL: 457.22 0.57% OUTLET: 451.20 INLET: 451.53 INTYP: 5 BEND: 60 DEG DIA/WIDTH: 4.0 Q-RATIO: 0.09 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 13. 92 PIPE NO. 3: JUNC NO. 3: 3. 49 455.02 * 0.012 1.35 1.30 3.25 3.25 3.11 3.49 2.05 122 LF -24"CP @ OVERFLOW-EL: 458.57 0.60% OUTLET: 451.53 INLET: 452.26 INTYP: 5 BEND: 90 DEG DIA/WIDTH: 4.0 Q-RATIO: 0.01 Q(CFSI HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 12.81 PIPE NO. 4: JUNC NO. 4: 3. 75 456.01 * 0.012 1.29 1.21 3.49 3.49 3.10 3.75 2.27 14 LF -18"CP @ OVERFLOW-EL: 458.29 2.00% OUTLET: 452.50 INLET: 452. 78 INTYP: 5 BEND: 90 DEG DIA/WIDTH: 2.5 Q-RATIO: 0.11 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 12.69 PIPE NO. 5: JUNC NO. 5: 4.88 457.66 * 0.012 1.35 1.01 3.51 3.51 3.41 4.88 3.31 72 LF -18"CP @ OVERFLOW-EL: 459.02 1.00% OUTLET: 452.78 INLET: 453.50 INTYP: 5 BEND: 20 DEG DIA/WIDTH: 4.0 Q-RATIO: 0.01 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 11. 41 PIPE NO. 6: JUNC NO. 6: 2.10 455.60 * 0.012 1.29 1.24 4.88 4.88 1.50 1.92 2.10 57 LF -18"CP @ OVERFLOW-EL: 459.52 1.00% OUTLET: 453.50 INLET: 454.07 INTYP: 5 BEND: 68 DEG DIA/WIDTH: 4.0 Q-RATIO: 1.47 Q (CFS) HW (FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI 11.28 3.16 457.23 * 0.012 1.29 1.22 2.10 2.10 2.10 3.16 2.73 PIPE NO. 7: 32 LF -15"CP. @ 7.09% OUTLET: 455.06 INLET: 457.33 INTYP: 5 JUNC NO. 7: OVERFLOW-EL: 460.89 BEND: 45 DEG DIA/WIDTH: 2.0 Q-RATIO: 0.01 Q(CFS) HW (FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 4.56 PIPE NO. 8: JUNC NO. 8: 1. 23 458.56 * 0.012 0.87 0.43 2.17 2.17 0.87 ***** 1. 23 28 LF -15"CP @ OVERFLOW-EL: 460.89 1.00% OUTLET: 457.33 INLET: 457.61 INTYP: 5 BEND: 45 DEG DIA/WIDTH: 2.0 Q-RATIO: 0.03 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 4.50 PIPE NO. 9: JUNC NO. 9: 1. 31 458.92 * 0.012 0.86 0.73 1.23 1.23 0.98 1. 31 1. 26 79 LF -15"CP @ OVERFLOW-EL: 463.21 1.00% BEND: OUTLET: 457.61 INLET: 458.40 INTYP: 5 0 DEG DIA/WIDTH: 2.0 Q-RATIO: 0.21 Q (CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 4.35 PIPE N0.10: JUNC N0.10: 1. 07 459.47 * 0.012 0.85 0.72 1.31 1.31 0.85 ***** 1. 07 97 LF -12"CP @ 1.48% OVERFLOW-EL: 466.06 BEND: OUTLET: 458.65 INLET: 460.09 INTYP: 5 5 DEG DIA/WIDTH: 4.0 Q-RATIO: 0.69 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 3.60 PIPE N0.11: JUNC N0.11: 1. 44 461.53 * 0.012 0.81 0.66 0.82 0.82 0.81 ***** 1. 4 4 204 LF -12"CP @ OVERFLOW-EL: 469.48 0.60% OUTLET: 460.09 INLET: 461.31 INTYP: 5 BEND: 15 DEG DIA/WIDTH: 4.0 Q-RATIO: 0.03 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 2.13 PIPE N0.12: JUNC N0.12: 0.94 462.25 * 0.012 0.63 0.63 1.44 1.44 0.81 0. 94 0.86 123 LF -12"CP @ OVERFLOW-EL: 466.39 0.65% OUTLET: 461.31 INLET: 462.11 INTYP: 5 BEND: 90 DEG DIA/WIDTH: 2.0 Q-RATIO: 0.18 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 2.07 0.98 463.09 * 0.012 0.62 0.60 0.94 0.94 0.62 ***** 0.98 PIPE N0.13: 28 LF -12"CP @ 1.00% OUTLET: 462.11 INLET: 462.39 INTYP: 5 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 1. 76 0.77 463.16 * 0.012 0.57 0.48 0.98 0.98 0.71 0.77 0.70 BACKWATER COMPUTER PROGRAM FOR PIPES Pipe data from file:10-23.bwp Surcharge condition at intermediate junctions Tailwater Elevation:457.23 feet Discharge Range: 6. 34 to 6. 34 Step of 1. [cfs J Overflow Elevation:499.04 feet Weir:NONE Upstream Velocity:3. feet/sec PIPE NO. 1: JUNC NO. 1: 95 LF -12"CP @ 10.78% OVERFLOW-EL: 468.57 BEND: OUTLET: 455.06 INLET: 465.30 INTYP: 5 0 DEG DIA/WIDTH: 2.0 Q-RATIO: 0.39 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 6.34 PIPE NO. 2: JUNC NO. 2: 2.84 468.14 * 0.012 0.97 0.51 2.17 2.17 0.97 ***** 2.84 109 LF -12"CP @ 10.37% OUTLET: 465.30 INLET: 476.60 INTYP: 5 OVERFLOW-EL: 480.23 BEND: 85 DEG DIA/WIDTH: 2.0 Q-RATIO: 0.08 Q (CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 4. 56 PIPE NO. 3: JUNC NO. 3: 2.08 478.68 * 0.012 0.90 0.42 2.84 2.84 0.90 ***** 2.08 24 LF -12"CP @ OVERFLOW-EL: 481.40 4. 67% BEND: OUTLET: 476.60 INLET: 477.72 INTYP: 5 0 DEG DIA/WIDTH: 2.0 Q-RATIO: 0.29 Q (CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 4. 22 PIPE NO. 4: JUNC NO. 4: 1. 59 479.31 * 0.012 0.87 0.51 2.08 2.08 0.87 ***** 1. 59 160 LF -12"CP @ OVERFLOW-EL: 489.71 4.82% BEND: OUTLET: 477.72 INLET: 485.43 INTYP: 5 0 DEG DIA/WIDTH: 2.0 Q-RATIO: 0.49 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 3.27 PIPE NO. 5: JUNC NO. 5: 1. 26 486.69 * 0.012 0.78 0.44 1.59 1.59 0.78 ***** 1. 26 172 LF -12"CP @ 5.43% OVERFLOW-EL: 499.38 BEND: OUTLET: 485.43 INLET: 494.77 INTYP: 5 0 DEG DIA/WIDTH: 2.0 Q-RATIO: 0.62 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 2.19 PIPE NO. 6: JUNC NO. 6: 0.93 495.70 * 0.012 0.64 0.34 1.26 1.26 0.64. ***** 0.93 70 LF -12"CP @ 0.61% OVERFLOW-EL: 501.51 BEND: OUTLET: 494.77 INLET: 495.20 INTYP: 5 6 DEG DIA/WIDTH: 4.0 Q-RATI0:20.31 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 1. 36 0. 77 495.97 * 0.012 0.50 0.47 0.93 0.93 0.57 0. 77 0.71 PIPE NO. 7: 43 LF -12"CP @ 0.86% OUTLET: 495.20 INLET: 495.57 INTYP: 5 Q (CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 0.06 0.41 4 95. 98 * 0.012 0.11 0.10 0.77 0.77 0.41 0.27 0.10 BACKWATER COMPUTER PROGRAM FOR PIPES Pipe data from file:18-24A.bwp Surcharge condition at intermediate junctions Tailwater Elevation:478.68 feet Discharge Range:0.41 to 0.41 Step of 1. [cfs] Overflow Elevation:485.41 feet Weir:NONE Upstream Velocity:3. feet/sec PIPE NO. 1: 57 LF -12"CP @ 9.68% OVERFLOW-EL: 485.41 BEND: OUTLET: 476.60 INLET: 482.12 INTYP: 5 JUNC NO. 1: 0 DEG DIA/WIDTH: 2.0 Q-RATIO: 1.02 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 0.41 0.31 482.43 * 0.012 0.27 0.13 2.08 2.08 0.27 ***** 0.31 PIPE NO. 2: 86 LF -12"CP @ 0.33% OUTLET: 482.12 INLET: 482.40 INTYP: 5 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 0.20 0.21 482.61 * 0.012 0.19 0.21 0.31 0.31 0.21 0.14 0.11 BACKWATER COMPUTER PROGRAM FOR PIPES Pipe data from file:4-35.bwp Surcharge condition at intermediate junctions Tailwater Elevation:453.69 feet Discharge Range:7.06 to 7.06 Step of 1. [cfs] Overflow Elevation:512.15 feet Weir:NONE Upstream Velocity:3. feet/sec PIPE NO. 1: 238 LF -15"CP @ 8.78% OVERFLOW-EL: 478.31 BEND: OUTLET: 451.15 INLET: 472.05 INTYP: 5 JUNC NO. 1: 0 DEG DIA/WIDTH: 4.0 Q-RATIO: 0.05 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 7.06 PIPE NO. 2: JUNC NO. 2: 1. 66 473.71 * 0.012 1.07 0.51 2.54 2.54 1.07 ***** 1. 66 54 LF -15"CP @ OVERFLOW-EL: 482.06 6.91% OUTLET: 472.05 INLET: 475.78 INTYP: 5 BEND: 60 DEG DIA/WIDTH: 4.0 Q-RATIO: 0.01 Q(CFS) HW (FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 6.75 PIPE NO. 3: JUNC NO. 3: 1. 83 477.61 * 0.012 1.05 0.53 1.66 1.66 1.05 ***** 1. 83 44 LF -15"CP @ OVERFLOW-EL: 484.25 5.05% OUTLET: 475.78 INLET: 478.00 INTYP: 5 BEND: 90 DEG DIA/WIDTH: 4.0 Q-RATIO: 0.19 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 6. 70 2.36 480.36 * 0.012 1.05 0.57 1.83 1.83 1.05 ***** 2.36 PIPE NO. 4: 28 LF -12"CP @ 12.50% OUTLET: 478.00 INLET: 481.50 INTYP: 5 JUNC NO. 4: OVERFLOW-EL: 484.51 BEND: 85 DEG DIA/WIDTH: 2.5 Q-RATIO: 0.09 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 5.65 PIPE NO. 5: JUNC NO. 5: 2.85 484.35 * 0.012 0.95 0.45 2.36 2.36 0.95 ***** 2.85 178 LF -12"CP @ 6.65% OVERFLOW-EL: 497.15 BEND: OUTLET: 481.50 INLET: 493.34 INTYP: 5 0 DEG DIA/WIDTH: 2.0 Q-RATIO: 0.04 Q(CFS) HW (FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 5.17 PIPE NO. 6: JUNC NO. 6: 1. 78 495.12 * 0.012 0.93 0.52 2.85 2.85 0.93 ***** 1. 78 67 LF -12"CP @ 1.00% OVERFLOW-EL: 497.63 BEND: OUTLET: 493.34 INLET: 494.01 INTYP: 5 0 DEG DIA/WIDTH: 2.0 Q-RATIO: 0.53 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 4.96 2.98 496.99 * 0.012 0.92 1.00 1.78 1.78 2.22 2.98 2.09 PIPE NO. 7: 143 LF -12"CP @ 5.81% OUTLET: 494.01 INLET: 502.32 INTYP: 5 JUNC NO. 7: OVERFLOW-EL: 505.95 BEND: 0 DEG DIA/WIDTH: 2.0 Q-RATIO: 2.24 Q (CFS) HW(FT) HW ELEV. * N-FAC DC ON TW DO DE HWO HWI ******************************************************************************* 3.23 PIPE NO. 8: JUNC NO. 8: 1. 31 503.63 * 0.012 0.78 0.41 2.98 2.98 0.78 ***** 1. 31 173 LF -12"CP @ OVERFLOW-EL: 512.09 2.82% OUTLET: 502.32 INLET: 507.20 INTYP: 5 BEND: 15 DEG DIA/WIDTH: 2.0 Q-RATIO: 0.00 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 1. 00 PIPE NO. 9: JUNC NO. 9: 0.56 507.76 * 0.012 0.42 0.27 1.31 1.31 0.42 ***** 0.56 37 LF -12"CP @ OVERFLOW-EL: 511.70 0.54% OUTLET: 507.20 INLET: 507.40 INTYP: 5 BEND: 80 DEG DIA/WIDTH: 2.0 Q-RATIO: 0.04 Q(CFS) HW (FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 1. 00 PIPE N0.10: JUNC N0.10: 0.59 507.99 * 0.012 0.42 0.41 0.56 0.56 0.42 ***** 0.59 28 LF -12"CP @ 0.71% OVERFLOW-EL: 511.70 BEND: OUTLET: 507.40 INLET: 507.60 INTYP: 5 0 DEG DIA/WIDTH: 2.0 Q-RATIO: 0.07 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 0.96 0.56 508.16 * 0.012 0.42 0.38 0.59 0.59 0.42 ***** 0.56 PIPE N0.11: 9 LF -12"CP @ 1.00% OUTLET: 507.60 INLET: 507.69 INTYP: 5 Q(CFS) HW(FT) HW ELEV. * N-FAC DC ON TW DO DE' HWO HWI ******************************************************************************* 0.89 0.47 508.16 * 0.012 0.40 0.33 0.56 0.56 0.44 0. 47 0. 41 BACKWATER COMPUTER PROGRAM FOR PIPES Pipe data from file:29-37.bwp Surcharge condition at intermediate junctions Tailwater Elevation:495.12 feet Discharge Range:0.22 to 0.22 Step of 1. [cfs) Overflow Elevation:499.38 feet Weir:NONE Upstream Velocity:3. feet/sec PIPE NO. 1: 62 LF -12"CP @ OVERFLOW-EL: 499.30 4.37% OUTLET: 493.34 INLET: 496.05 INTYP: 5 JUNC NO. 1: BEND: 90 DEG DIA/WIDTH: 2.0 Q-RATIO: 0.99 Q(CFS) HW (FT) HW ELEV. * N-FAC DC ON TW DO DE HWO HWI ******************************************************************************* 0.22 0.24 496.29 * 0.012 0.20 0.12 1.78 1.78 0.20 ***** 0.24 PIPE NO. 2: 35 LF -12"CP @ 1.00% OUTLET: 496.05 INLET: 496.40 INTYP: 5 Q(CFS) HW(FT) HW ELEV. * N-FAC DC ON TW DO DE HWO HWI ******************************************************************************* 0.11 0.14 496.54 * 0.012 0.14 0.12 0.24 0.24 0.14 ***** 0.12 BACKWATER COMPUTER PROGRAM FOR PIPES Pipe data from file:POND-44.bwp Surcharge condition at intermediate junctions Tailwater Elevation:453. feet Discharge Range:1.29 to 1.29 Step of 1. (cfs) Overflow Elevation:516.09 feet Weir:NONE Upstream Velocity:3. feet/sec PIPE NO. 1: 83 LF -12"CP @ 10.24% OUTLET: 448.80 INLET: 457.30 INTYP: 5 JUNC NO. 1: OVERFLOW-EL: 462.16 BEND: 90 DEG DIA/WIDTH: 2.0 Q-RATIO: 0.20 Q(CFSJ HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 1. 29 PIPE NO. 2: JUNC NO. 2: 0.66 457.96 * 0.012 0.48 0.22 4.20 4.20 0.48 ***** 0.66 290 LF -12"CP @ OVERFLOW-EL: 486.31 8.87% BEND: OUTLET: 457.30 INLET: 483.03 INTYP: 5 0 DEG DIA/WIDTH: 2.0 Q-RATIO: 0.14 Q(CFSJ HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 1. 07 PIPE NO. 3: JUNC NO. 3: 0.56 483.59 * 0.012 0.44 0.21 0.66 0.66 0.44 ***** 0.56 149 LF -12"CP @ OVERFLOW-EL: 496.01 6.56% BEND: OUTLET: 483.03 INLET: 492.80 INTYP: 5 0 DEG DIA/WIDTH: 2.0 Q-RATIO: 0.19 Q(CFSJ HW(FTJ HW ELEV. * N-FAC DC DN TW DO DE HWO HWI *****************************************************************************~* 0.94 PIPE NO. 4: JUNC NO. 4: 0.53 493.33 * 0.012 0.41 0.21 0.56 0.56 0.41 ***** 0.53 157 LF -12"CP @ OVERFLOW-EL: 503.79 4.75% BEND: OUTLET: 492.80 INLET: 500.25 INTYP: 5 0 DEG DIA/WIDTH: 2.0 Q-RATIO: 0.19 Q(CFSJ HW(FTJ HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 0.79 PIPE NO. 5: JUNC NO. 5: 0.49 500.74 * 0.012 0.38 0.21 0.53 0.53 0.38 ***** 0. 4 9 125 LF -12"CP @ 3.52% OVERFLOW-EL: 508.18 BEND: OUTLET: 500.25 INLET: 504.65 INTYP: 5 0 DEG DIA/WIDTH:. 2. 0 Q-RATIO: 0. 4 7 Q(CFSJ HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 0.66 PIPE NO. 6: JUNC NO. 6: 0. 45 505.10 * 0.012 0.34 0.21 0.49 0.49 0.34 ***** 0.45 193 LF -12"CP @ 2.41% OVERFLOW-EL: 512.77· BEND: OUTLET: 504.65 INLET: 509.30 INTYP: 5 0 DEG DIA/WIDTH: 2.0 Q-RATIO: 0.93 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 0. 4 5 0.37 509.67 * 0.012 0.28 0.19 0.45 0.45 0.28 ***** 0.37 PIPE NO. 7: 170 LF -12"CP @ 1.00% OUTLET: 509.30 INLET: 511.00 INTYP: 5 Q (CFS) HW (FT) HW ELEV. * N-FAC DC ON TW DO DE HWO HWI ******************************************************************************* 0.23 0.20 511. 20 * 0.012 0.20 0.17 0.37 0.37 0.20 ***** 0.17 .J East Renton/Rosemonte -Technical Information Report 6 SPECIAL REPORTS AND STUDIES 6.1 Geotechnical Reports Please refer to the report Rosemonte-East Renton Property, by Associated Earth Science, Inc. dated November 12, 2007 located at the end of this section. 6.2 Wetland Determination Report Please refer to the report Wetland Determination for East Renton Property, by C. Gary Shulz dated September 12, 2002. 6.3 Wetland Recharge There are approximately 9.5 acres of wetlands and associated buffers (wetland complex) occupying the western portions of the two plats of East Renton/Rosemonte. On the attached Existing Wetland Tributary Area Exhibit these wetlands are identified as B, C, E and F. Wetlands B and C are located within the East Renton site and Wetland E and F are located within the Rosemonte site. This complex receives sheet flow runoff from the remaining upland portions of both sites. With development, it is proposed that both projects will be served by one detention facility (large combined detention/WQ treatment pond), located in a tract in the northeast corner of Rosemonte. This pond will be sized to provide Level One flow control -discharge from the pond will provide recharge to wetland F. In order to maintain hydrology to the remainder of the wetland complex, the yearly volume of runoff from the upslope area draining to it was calculated utilizing King County Runoff Time Series (KCRTS) methodology. Using KCRTS, the existing basin's I.I-year storm peak was determined to occur on 3/24/04. This date was then bracketed (6-months before and 6- months after) and the time series analyzed to determine the total annual runoff volume during that I-year period. The I. I year storm was selected because it is the lowest intensity and highest frequency storm that KCRTS can model. Under developed conditions, the goal is to maintain hydrology by recharging the wetland complex with runoff from the roofs and backyards of selected lots. The number of lots Job#01-047 August 7, 2008 Page 6-1 East Renton/Rosemonte -Technical Information Report (together with some open space tract area) needed to provide recharge equivalent to the existing conditions annual I. I-year volume was determined by time series iteration. These lots are situated adjacent to or near the wetland complex, with runoff distributed to each wetland via discharge from individual lot splash blocks. (See Developed Wetland Recharge Area Exhibit] For those recharge roof areas with tight line systems high enough in elevation to physically drain to the detention pond (lots 72-75), a flow splitter will be used to divert flows exceeding the I. I-year peak flow to the pond. Recharge roof and yard area runoff that does not get routed to the pond (portions of Lots 9 -19, 76 -78, Tracts Hand K) will be treated as "bypass" area, and will be compensated for during detention pond sizing. 6.3.1 Predeveloped Land Cover WETLANDB&C In the existing condition, 6.53 acres of the site is tributary to wetland B and C located near the western property line. This area is to be diverted away from the wetland after development. The following is a breakdown of the pre developed land cover. I. 96 acres Fore st 0.09 acres Impervious (driveways and roofs with 50% impervious multiplier) 4.48 acres Till Pasture 6.53 acres Total KCRTS Existing Peak B and C Flows Flow Frequency Analysis Time Series File:ext b ,& c.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- Flow Rate Rank (CFS) 0.453 2 0.169 7 0. 403 3 0.045 8 0.229 6 0.379 4 0.361 5 0. 724 1 Computed Peaks Job #01-047 August 7, 2008 Time of Peak 2/09/01 18:00 1/05/02 16:00 2/28/03 3:00 3/24/04 19:00 1/05/05 8:00 1/18/06 16:00 11/24/06 4:00 1/09/08 6:00 -----Flow Frequency Analysis------- --Peaks Rank Return Prob (CFS) Period 0. 724 1 100.00 0.990 0. 453 2 25.00 0.960 0. 403 3 10.00 0.900 0.379 4 5.00 0.800 0.361 5 3.00 0.667 0.229 6 2.00 0.500 0.169 7 1. 30 0.231 0.045 8 1.10 0.091 0.634 50.00 0.980 Page 6-2 East Renton/Rosemonte -Technical Information Report KCRTS Existinl( Band C Volume Discharge Volume from Time Series ext b & c.tsf between 09/24/03 00:00 and 09/23/04 23:59 39072. CU-Ft or 0.897 Ac-Ft in 365.0 days WETLANDE&F In the existing condition, 2.50 acres of the site is tributary to wetland E and F located near the northwest comer of the site. This area is to be diverted away from the wetland after development. The following is a breakdown of the pre developed land cover. 2.50 acres Till Pasture 2.50 acres Total KCRTS Existing Peak E and F Flows Flow Frequency Analysis Time Series File:ext e & f.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--------Flow Frequency Analysis------- Flow Rate Rank Time of Peak --Peaks (CFS) (CFS) 0.176 2 2/09/01 18:00 0.302 0.066 7 1/05/02 16:00 0.176 0.161 3 2/28/03 3:00 0.161 0.017 8 3/24/04 19:00 0 .150 0.090 6 1/05/05 8:00 0.145 0.150 4 1/18/06 16:00 0.090 0.145 5 11/24/06 4:00 0.066 0.302 1 1/09/08 6:00 0.017 Computed Peaks 0. 260 KCRTS Existing E and F Volume Discharge Volume from Time Series ext e & f. tsf between 09/24/03 00:00 and 09/23/04 23:59 Rank 1 2 3 4 5 6 7 8 18318. CU-Ft or 0.421 Ac-Ft in 365.0 days Job #01-047 August?,2008 Return Prob Period 100.00 0.990 25.00 o. 960 10.00 0.900 5.00 0.800 3.00 0. 667 2.00 0.500 1. 30 0.231 1.10 0.091 50.00 0.980 Page 6-3 East Renton/Rosemonte -Technical Information Report 6.3.2 Developed Land Cover WETLANDB&C In the developed condition, 1.32 acres of the site will be directed to wetland B and C located near the western property line. This area consisted of lots 9-19 (rear yards, side yards, and roofs) and Recreation Tract H. The following is a breakdown of the developed land cover. 0.41 acres Impervious 0.91 acres Till Grass 1.32 acres Total KCRTS Develooed Peak B and C Flows Flow Frequency Analysis Time Series File:dev b & c.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--------Flow Frequency Analysis------- Flow Rate Rank Time of Peak (CFS) 0.180 4 2/09/01 2:00 0.129 7 1/05/02 16:00 0.221 2 2/27/03 7:00 0.119 8 8/26/04 2:00 0.148 6 10/28/04 16:00 0.190 3 1/18/06 16:00 0.177 5 11/24/06 3:00 0.386 1 1/09/08 6:00 Computed Peaks KCRTS Develoned Band C Volume Discharge Volume from Time Series dev b & c.tsf --Peaks (CFS) 0.386 0.221 0.190 0.180 0.177 0 .148 0.129 0.119 0.331 between 09/24/03 00:00 and 09/23/04 23:59 Rank 1 2 3 4 5 6 7 8 38117. Cu-Ft or 0.875 Ac-Ft in 365.0 days Job #01-047 August 7, 2008 Basin Band C Existing Volume= Q 1.1 = 39,072 cu-ft Developed Volume= Q1.1 = 38,117 cu-ft Return Prob Period 100.00 0.990 25.00 0. 960 10.00 0.900 5.00 0. 800 3.00 0. 667 2.00 0.500 1. 30 0.231 1.10 0.091 50.00 0.980 Page 6-4 East Renton/Rosemonte -Technical Information Report 6.3.3 Developed Land Cover WETLANDE&F In the developed condition, 0.60 acres of the site will be directed to wetland E and F located near the northwest corner of the developed site. This area consisted of lots 72-75 (roofs), and Open Space Tract H and K. The pond outflow is also tributary to wetland E but is not considered in this analysis. The pond outflow is located below wetland E and a portion of wetland F. The following is a breakdown of the developed land cover. 0.4 I acres Impervious 0. 91 acres Till Grass 1.32 acres Total KCRTS Developed Peak E and F Flows Flow Frequency Analysis Time Series File:dev e & f.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--------Flow Frequency Analysis------- Flow Rate Rank Time of Peak --Peaks Rank Return Prob (CFS) 0.089 5 0.066 7 0.108 2 0.064 8 0.079 6 o. 094 3 0.093 4 0.187 1 Computed Peaks 2/09/01 2:00 1/05/02 16:00 2/27/03 7:00 8/26/04 2:00 10/28/04 16:00 1/18 /06 16:00 10/26/06 0:00 1/09/08 6:00 I CFS) Period 0.187 1 100.00 0.108 2 25.00 0.094 3 10.00 0.093 4 5.00 0.089 5 3.00 0.079 0.066 0.064 0.161 6 7 8 2.00 1. 30 1.10 50.00 KCRTS Developed E and F Volume Discharge Volume from Time Series dev e & f.tsf between 09/24/03 00:00 and 09/23/04 23:59 19384. CU-Ft or 0.445 Ac-Ft in 365.0 days Job #01-047 August?,2008 Basin E and F Existing Volume= Q 1.1 = 18,318 cu-ft Developed Volume= Qu = 19,384 cu-ft 0.990 0.960 0.900 0.800 0. 667 0.500 0.231 0.091 0. 980 Page 6-5 ,. ~. / East Renton/Rosemonte -Technical Information Report 6.3.4 Wetland Flow Splitter The flow-splitter is sized to direct up to the I. I-year peak runoff of the roof area from lots 72-75 to a lever spreader located adjacent to wetland E. The roof area is based on 2,000 square feet per lot. The flow-splitter is located west of the lots, adjacent to 145th Avenue SE. The following is a breakdown of the developed land cover. 0.18 acres Impervious ( 4 x 2,000 sq-ft) 0.18 acres Total KCRTS Develo ed Peak Lots 71-74 Flows Flow Frequency Analysis Time Series File:lots71-74.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--------Flow Frequency Analysis------- Flow Rate Rank Time of Peak --Peaks Rank Retur:n Prob (CFS) (CFS) Period 0.044 7 2/09/01 2:00 0.085 1 100.00 0.990 0.038 8 1/05/02 16:00 0.065 2 25.00 0.960 0.053 4 12/08/02 18:00 0.053 3 10.00 0.900 0.045 6 8/26/04 2:00 0.053 4 5.00 0.800 0.053 3 10/28/04 16:00 0.047 5 3.00 0.667 0.047 5 1/18/06 16:00 0.045 6 2.00 0.500 0.065 2 10/26/06 0:00 0.044 7 1.30 0.231 0.085 1 1/09/08 6:00 0.038 8 1.10 0.091 Computed Peaks 0.079 50.00 0.980 All flows below 0.038 (I. I year flow rate) cfs will be routed to the wetland. The flow-splitter will be comprised of a stand-pipe with a single bottom orifice and an outlet pipe directed to the wetland, along with another outlet pipe designed to be connected to the site's conveyance system. The flow-splitter is designed using the orifice equation. Orifice Equation: Q = CA(2gh)05 Where Job#01-047 August7,2008 Q = flow rate (cfs) = 0.038 cfs C = coefficient of discharge= 0.62 (plate orifice) A = area of orifice (sf) Where A= Il(d/24)2 d = diameter (in) = 1.25" ( chosen) A =,0.0085 sf Page 6-6 East Renton/Rosemonte -Technical lnformati;m Report g = gravity (ft/sec2) = 32.2 ft/sec 2 h = hydraulic head above outlet pipe (ft) Rearranged for h: h = (Q/CA)2/2g h = (0.038/(0.62*0.0085))2/2(32.2) = 0.80ft The flow-splitter will be designed with a 6" stand-pipe along with a bottom plate orifice of I 1/4 (1.25) inches. Job #01-047 August 7, 2008 srA AND VAM STfPS 6" RES1RJCr()R OUllfr OF Tr CTION SHAL Bf Sll007HCD WALL IIErAL PIPC MITH OUT'SJOC D1Ail£TCR 1/f" LESS mAN INS10£ 0/AJl(r(R OF CONNECnNG P/Pf PLAN VIEW CB 68, TYPE 11-48" FL OW SPL!TTEP ROUND SOt.lD UX:XING LIO MARl<W 'DRAIN 'M'f'H LOCKING 8Gl7S; TOP Cl.E'I. 451.00 SCALC: I" • 2' STANDARO 571:PS OR LAOOCR 6" STAND PIPE ~ . . . ' ' SECTION VIEW CB 68, TYPE 11-48" FLOW SPLITTER SCALE: I" • 2' N Page 6-7 .... {::{/iti ;:-<~ ,·~iJ Geotechnical Engineering Water Resources Environmental Assessments and Remediation Sustainable Development Services Geologic Assessments Associated Earth Sciences, Inc. C6ilrr::111'!f .ij ~r::tr.r o/J}m1c6 Subsurface Exploration, Geologic Hazard, and Geotechnical Engineering Report ROSEMONT-EAST RENTON PROPERTY King County, Washington Prepared for CamWest Development, Inc . Project No. KE040766B November 12, 2007 , Associated Earth Sciences, Inc. ~~~~ ~~~~ Cefe6rafiYIJ Over 2.J 1/Mrs of.Service November 12, 2007 Project No. KE040766B Cam West Development, Inc. 9720 NE 120~ Place, Suite JOO Kirkland, Washington 98034 Attention: Ms. Jennifer Reiner Subject: Subsurface Exploration, Geologic Hazard, and Geotechnical Engineering Report Rosemont-East Renton Property King County, Washington Dear Ms. Reiner: We are pleased to present the enclosed copies of the above-referenced report. This report summarizes the results of our subsurface exploration, geologic hazard, and geotechnical engineering study, and offers recommendations for design and development of the proposed project. This report is intended to replace our April 23, 2003 geotechnical report completed for the "Ironwood Property" for Northward Homes. We have enjoyed working with you on this study and are confident that the recommendations presented in this report will aid in the successful completion of your project. Should you have any questions, or if we can be of additional help to you, please do not hesitate to call. Sincerely, ASSOCIATED EARTH SCIENCES, INC. Kirkland, Washington ~Q.\M· Kurt D. Merriman, P.E. Principal Engineer KDM!ts KE04766Bl ProJects\20040766\KE\WP --- Kirkland 425-827-770 I a Everett a Tacoma 425-259-0522 253-722-2992 www.aesgeo.com r SUBSURJFACE EXJl>LORATION, GEOLOGIC HAZARD, AND GEOTECHNICAL ENGINEERING REPORT RO§JEMON1r -JEA§1r RJENTON PROPJERTY King County, Washington Prepared for: CamWest Development, Inc. 9720 NE I 20'h Place, Suite JOO Kirkland, Washington 98034 Prepared by: Associated Earth Sciences, Inc. 911 5m Avenue, Suite JOO Kirkland, Washington 98033 425-827-7701 Fax: 425-827-5424 November 12, 2007 Project No. KE040766B Rosemont-East Renton Property King Cowrty, Washington Subswface Exploration, Geologic Hazard, and Geotechnical Engineering Repon Project and Site Conditions I. PROJECT AND SITE CONDITIONS 1.0 INTRODUCTION This report presents the results of our subsurface exploration, geologic hazard, and geotechnical engineering study for the Rosemont-East Renton Property located east of 148"' Avenue SE, roughly between SE I 17'" and SE 120'" Streets in King County, Washington. This report is intended to replace our previous report dated April 23, 2003 for the "Ironwood Property" prepared at that time for Northward Homes. CamWest Development, Inc. (CamWest) has subsequently purchased the property and combined it with the "East Renton" (southern portion of the site) and re-named the northern portion of the site "Rosemont." The site location is shown on Figure 1, "Vicinity Map." The recently completed site and grading plan and approximate locations of the explorations accomplished for this study are presented on the "Site and Exploration Plan," Figure 2. The explorations were completed in the general areas of the proposed lots, detention facilities, and streets. If development plans change, the conclusions and recommendations contained in this report should be reviewed and modified, or verified, if necessary. 1. I Purpose and Scope The purpose of this study was to provide subsurface soil and ground water data to be utilized in the design and development of the above-referenced project. Our study included a review of available geologic literature including soils data from the referenced 2003 report and supplemental exploration pits excavated within proposed detention tracts in 2004 and excavation of 12 new exploration pits. We also performed geologic studies to assess the type, thickness, distribution, and physical properties of the subsurface sediments and ground water 'conditions. Limited geologic hazard evaluations and engineering studies were also conducted to determine suitable geologic hazard mitigation techniques, the type of suitable foundations for new structures, allowable soil foundation bearing pressures, anticipated settlements, retaining wall lateral pressures, floor support recommendations, and drainage considerations. This report summarizes our current fieldwork and offers hazard mitigation and development recommendations based on our present understanding of the project. 1.2 Authorization Authorization to proceed with this study was granted by Cam West. This report has been prepared for the exclusive use of CamWest and their agents for specific application to this project. Within the limitations of scope, schedule, and budget, our services have been performed in accordance with generally accepted geotechnical engineering and engineering geology practices in effect in this area at the time our report was prepared. No other warranty, express or implied, is made. November 12, 2007 ASSOCIATED EARTH SCIENCES, INC. SG8hs-XE04766BI -Projtcls\10040166IKE\WP Page 4 Rosemnnt-East Renton Property King County, Washington 2.0 PROJECT AND SITE DESCRIPTION Subsurface Exploration, Geologic Hazard, and Geoteclmical Engineering Report Project and Site Conditions This report was completed with an understanding of the project based on conversations with Ms. Rebecca Cushman of Triad Associates, review of proposed lot and street layout and grading plans, review of King County Preliminary Plat Application review comments dated April JO, 2007, and familiarity with our previous geotechnical work performed in the site area. Present plans call for demolition of two existing houses and several outbuildings and the construction of 91 single-family units, new streets, two storm water detention facilities, and associated development improvements. Access to the new development will be from I 48'h A venue SE via a new residential collector designated on the referenced plans as SE 119"' Street. The site is located west of 148"' Avenue SE and east of the Renton city limits, approximately 14 mile south of SR 900 in King County, Washington. Wood-framed, single-family homes occupy the northeast and southeast corners of the property. Several large outbuildings are located west of both houses. A domestic water well is located near the northern homesite. The site slopes moderately down to the west to a wetland that occupies the western one-third of the property. The wetland contained both standing and flowing surface water at the time of our site visits. Total<§aluatio'!,:hange across the property is on the order of 100 feet. The east side of the site is predominately developed with pasture overgrown with blackberries and Scotch broom with scattered trees and grass within the areas surrounding the existing houses. The west side of the site is covered with wetland vegetation and mature trees. The area near the northwest site corner has been developed under a different CamWest plat. The site is surrounded by large tracts of rural and densely-spaced, new residential tracts. 3.0 SUBSURFACE EXPLORATION Our field study included advancing 19 exploration pits on April 8, 2003 within the Rosemont tract (formerly Ironwood Property), two exploration pits in 2004 within the proposed detention tracts, and 12 new exploration pits within the East Renton tract (formerly Rosemont). We completed three exploration borings on October 4, 2007 within the proposed detention facility footprints. We also performed a geologic reconnaissance to gain information about the site. The various types of sediments, as well as the depths where characteristics of the sediments changed, are indicated on the exploration logs presented in Appendix A. The depths indicated on the logs where conditions changed may represent gradational variations between sediment types. Our explorations were approximately located in the field by measuring from known site features shown on the "Site and Exploration Plan" and their locations and elevations should be considered approximate. November 12, 2007 ASSOCIATED EARTH SCIENCES, INC. SGB~s-KE04766BJ -Projem\200407661K£1WP Page 5 Rosemont-East Renton Property King Counl)I, Washington Subswface Exploration, Geologic Hazard, and Geoteclmical Engineering Report Project and Site Conditions The conclusions and recommendations presented in this report are based on the explorations completed for this and previous studies. The number, locations, and depths of the explorations were completed within site, time, and budgetary constraints. Because of the nature of exploratory work below ground, extrapolation of subsurface conditions between field explorations is necessary. It should be noted that differing subsurface conditions may sometimes be present due to the random nature of deposition and the alteration of topography by past grading and/or filling. The nature and extent of any variations between the field explorations may not become fully evident until construction. If variations are observed at that time, it may be necessary to re-evaluate specific recommendations in this report and make appropriate changes. 3 .1 Exploration Pits All exploration pits were excavated with a trackhoe either under subcontract to Associated Earth Sciences, Inc. (AES!) or CamWest. The pits permitted direct, visual observation of subsurface conditions. Materials encountered in the exploration pits were studied and classified in the field by an engineering geologist or geotechnical engineer from our firm. All exploration pits were backfilled immediately after examination and logging. Selected samples were then transported to our laboratory for further visual classification and testing, as necessary. Laboratory testing was only performed on the samples collected during our most recent subsurface exploration from the East Renton property. 3.2 Exploration Borings The exploration borings were completed by advancing a 33/a-inch, inside-diameter, hollow- stem auger with a track-mounted drill rig to depths ranging from 11.5 to 36.5 feet. During the drilling process, samples were obtained at generally 2.5-or 5-foot-depth intervals. The borings were continuously observed and logged by a geotechnical engineer from our firm. The exploration logs presented in Appendix A are based on the field logs, drilling action, and inspection of the samples secured. Disturbed but representative samples were obtained by using the Standard Penetration Test (SPT) procedure in accordance with American Society for Testing and Materials (ASTM):D 1586. This test and sampling method consists of driving a standard, 2-inch, outside-diameter, split-barrel sampler a distance of 18 inches into the soil with a 140-pound hammer free-falling a distance of 30 inches. The number of blows for each 6-inch interval is recorded and the number of blows required to drive the sampler the final 12 inches is known as the Standard Penetration Resistance ("N") or blow count. If a total of 50 is recorded within one 6-inch interval, the blow count is recorded as the number of blows for the corresponding number of inches of penetration. The resistance, or N-value, provides a measure of the relative density of granular soils or the relative consistency of cohesive soils; these values are plotted on the attached boring log. November 12, 2007 ASSOCIATED EARTH SCIENCES, INC. SGB/ls -KE04766Bl -Projtcrs\200407661 KE\ WP Page 6 -~ Rosemont-East Renton Property King County, Washington Subswjace Exploration, Geologic Hazard, and Geotechnical Engineering Repon Project and Site Conditions The samples obtained from the split-barrel sampler were classified in the field and representative portions placed in watertight containers. The samples were then transported to our laboratory for further visual classification and laboratory testing, as necessary. Laboratory testing data is summarized below and included in Appendix A. 4.0 SUBSURFACE CONDITIONS Subsurface conditions at the project site were inferred from the field explorations accomplished for this study and visual reconnaissance of the site. As shown on the field logs, the exploration pits generally encountered fill materials of various thickness and composition near the northwest and southeast corners of the proposed development area overlying various glacially derived sediments. In one exploration pit near the southwestern corner of the proposed development area, we identified colluvium over glacial recessional outwash sediments overlying pre-Vashon sedimentary deposits consisting of stiff to hard peat and silt. Although isolated areas of outwash were encountered near the ground surface, till was the predominant soil encountered throughout the site, as mapped on Figure 2. At this site there appears to be a somewhat thin till cap along the upper elevations of the property that thickens to the southeast. The site slopes down to the west and northwest into a large, eroded (during the Pleistocene), roughly north-south trending valley. Where recessional outwash was encountered and not underlain by till, the till was likely eroded during formation of this valley. The recessional outwash was then likely deposited directly upon the underlying sediments identified within the northern explorations as advance outwash or pre-Fraser (interglacial) sedimentary deposits at the southwest development area. Figure 3 presents a cross section through the proposed storm water detention pond (Section A-A' on Figure 2). Review of the Geologic Map of King County, Washington, by Derek Booth, et al. (2006) indicates that the area of the subject site is underlain by Vashon lodgement till with advance outwash and wetland deposits mapped to the west. Our interpretations of the sediments encountered during our study are in general agreement with this regional geologic map. The following section presents more detailed subsurface information organized from the shallowest (youngest) to the deepest (oldest) sediment types. 4.1 Stratigraphy Brush/Forest Duff/Topsoil/Colluvium A layer of organic-rich soil classified as sod or brush, forest duff, topsoil, and/or colluvium was encountered at the surface in all of the exploration pits. The organic-rich soil was between 0.5 and 1.5 feet thick. In EP-4 (2007) a layer of colluvium approximately 4 feet thick was encountered. Colluvium is soil that has moved downslope by the forces of gravity. These November 12, 2007 ASSOCIATED EARTH SCIENCES, INC. SGB//t-KE04766BI -Projectsl20040766IKE\WP Page 7 Rosemont-East Renton Property King Cou11ty, Washington Subswface Exploration, Geologic Hazard, and Geotechnical Engineering Repo11 Project and Site Conditions soils are not considered suitable for structural, roadway, or fill slope support due to its compressive and unstable nature. Fill Approximately 1.5 to JO feet of fill was encountered in the exploration pits located primarily in the northwest and southeast corners of the proposed development area (See Figure 2). The fill was encountered in recent exploration pits EP-1 and EP-2, and in the 2003 exploration pits EP-11, EP-12, EP-13, EP-17, and EP-18. Fill is also expected around the existing homes, outbuildings, septic systems, and other existing underground utilities. The fill generally consisted of loose, moist to wet, fine to coarse sand with variable amounts of silt, gravel, organic material, and debris such as concrete and asphalt chunks. The fill is not considered suitable for foundation, fill slope, roadway, or utility support due to its loose and variable condition and organic and debris content. Vashon Recessional Outwash A recessional outwash deposit consisting of medium dense, stratified sand and silty sand with variable amounts of gravel was encountered in exploration pit EP-4 and exploration boring EB-2 (2007) and exploration pits EP-12, EP-13, EP-14, and EP-16 (2003), primarily in explorations completed nearest the on-site wetland. Meltwater streams flowing off of the retreating Vashon-age ice sheet that once occupied the Puget Sound area deposited the recessional outwash sand. The recessional outwash is suitable for building support, though some preparation and compaction may be needed prior to placement of structures on this material. The recessional outwash is estimated to have a high permeability rate, but is somewhat stratified which will limit its permeability. Within the proposed detention pond area, the recessional outwash is composed primarily of low-permeability silt. Vashon Lodgment Till Vashon Lodgment till was encountered in all 2007 explorations except EP-4, and in EP-2 and EP-3 (2004), and EP-16, EP-18, and EP-21 (2003). The till consisted of medium dense grading to very dense, silty fine to coarse sand containing fine to coarse gravel and cobbles and occasional boulders. The medium dense to very dense till is suitable for structural support, and is considered moisture-sensitive. The lodgment till was deposited at the base of the Vashon-age glacial ice sheet and was subsequently overridden by several thousand feet of ice. Consequently, these materials are generally dense to very dense, possess high shear strength, low compressibility characteristics, and are relatively impermeable. The upper portions of the till are generally weathered and less dense, oxidized brown, and siltier than the lower, unweathered portions of the deposit. The site can be considered a "till" site hydrologically, given that till covers the majority of the development area. November 12, 2007 ASSOCIATED EARTH SCIENCES, INC. SGBhJ -KE04766B/ -Projec1s\200407661K£\WP Page 8 Rosemont-East Renton Property King County, Washington Vashon Advance Outwash Snbsutface Exploration, Geologic Hazard, and Geotechnical Engineering Report Project and Site Conditions An advance outwash deposit consisting of medium dense to dense sand and gravel to hard sandy silt was encountered below the till in EP-6, EB-I, EB-2, and EB-3 (2007). Advance outwash was also encountered in exploration pits EP-15 through EP-22 (2003) either beneath the till or overlying fill, recessional outwash, or topsoil. Meltwater streams flowing off of the advancing Vashon-age glacial ice sheet.that once occupied the Puget Sound area deposited the outwash ahead of the glacial front and were subsequently overridden by several thousand feet of ice. The advance outwash deposit is suitable for building support. The advance outwash is estimated to have a wide range of permeability rates as it is highly stratified and over- consolidated. Pre-Fraser Sedimentary Deposits In EP-4 (2007), we encountered stiff to hard, interbedded, dark brown, organic peat and silt. These sediments were likely deposited in a wetland setting during the last inter-glacial period prior to the glacial ice sheet occupying this area of the Puget Sound. The depth and aerial extent of this interbedded peat/silt deposit is currently unknown. However, given the over- consolidated narure of this deposit, it is unlikely that significant settlement of fill or strucrures placed over these sediments will occur during the life of the project. 4.2 Hydrology Varying amounts of shallow ground water seepage, ranging from very heavy to very slight, were encountered in most of the exploration pits excavated in April of 2003. Ground water seepage was encountered in EP-4, EB-I, and EB-3 during our recent exploration program. Advance outwash soils identified in EP-6 and EB-2 were also wet and/or mottled indicating that seasonal ground water likely occurs to supply water to the nearby wetlands. The ground water seepage encountered in our exploration pits is interpreted to be perched in the looser soils or coarser-grained soils, such as the fill, the recessional outwash, the weathered till, and the advance outwash. The quantity and duration of seepage of the perched ground water was quite variable and depends on topography, soil grain size, on-and off-site land usage, and seasonal variations in the amount of precipitation. 4.3 KCRTS Soil Group Considerations Based on the site-specific explorations completed for this srudy, it is our opinion site soils should generally be considered till for purposes of King County Runoff Time Series (KCRTS) modeling. As illustrated on Figure 2, most of the proposed development area is underlain by till. Isolated areas of recessional or advance outwash have a limited distribution on the site. November 12, 2007 ASSOCIATED EARTH SCIENCES, INC. SGBhs -KEJ)4766BJ -Projursl20040766IKE\WP Page 9 Rosemont-East Renton Property King County, Washington 4.4 Laboratory Test Results Subsurface Exploration, Geologic Hazard, and Geotechnical Engineering Report Project and Site Conditions Laboratory testing on selected soil samples from explorations was completed in accordance with the requirements set forth in the request for proposal issued by Cam West. Laboratory testing results are also included in Appendix A. Moisture contents were tested in accordance with ASTM:D 2216. Grain size analysis was performed in accordance with ASTM:D 422 and D 1140. The maximum dry density of three soil samples was determined using the modified Proctor test procedure (ASTM:D 1557). The results are as follows in Table I. Other · laboratory test results are included in Appendix A. Table 1 Maximum Dry Density Optimum Moisture Content Samole Location SamoleTvne (ocf)"' (nercent)'" EP-1@3-4' Till (south oarcel) 121.0 12.5 EP-2@ 1.5 -4' Weathered Till (south) 118.0 14.5 EP-15@ 6' Till (north parcel) 137.0 9.5 (l) pd = pounds per cubic foot. (l> Reported results are not corrected for gravel content. November 12, 2007 ASSOCIATED EARTH SCIENCES, INC. SGB/11 -K£04766Bl -Projtcu12D040766] KE\ WP Page 10 Rosemont-East Renton Property King County. Washington S11bs111face Exploration, GeologicHazard, and Geotechnical Engineering Report Geologic Hazards and Mitigations II. GEOLOGIC HAZARDS AND MITIGATIONS The following discussion of potential geologic hazards is based on the geologic conditions as observed and discussed herein. The King County Sensitive Areas Folio was reviewed and no Landslide Areas or Erosion Hazard areas were shown for the site. 5.0 SLOPE STABILITY HAZARDS AND RECOMMENDED MITIGATION The site contains moderate slopes, especially along the western edge of the proposed development area. However. none of the slopes appear to exceed the King County criteria for steep slopes of greater than 40 percent inclination. Where these slopes contain fill, colluvium and recessional outwash, the risk of landsliding, especially during seismic shaking, is generally moderate. However, provided loose soil and colluvium are removed during site grading and our recommendations for keying and benching any new fill into the existing slopes are followed, it is our opinion that the risk of slope instability will be mitigated. Where till or advance outwash underlie the moderately inclined slopes, the risk of landsliding is considered low. 6.0 SEISMIC HAZARDS AND RECOMMENDED MITIGATION Earthquakes occur in the Puget Lowland with great regularity. Most of the seismic events are small and are usually not felt by people. However, large earthquakes do occur as evidenced by the 1949, 7.2-magnitude event, the 1965, 6.5-magnitude event, and the 2001, 6.8-magnitude event. The 1949 earthquake appears to have been the largest in this region during recorded history and was centered in the Olympia area. Evaluation of earthquake return rates indicates that an earthquake of the magnitude between 5.5 and 6.0 is every 25 to 40 years in the Puget Sound Basin. Generally, there are four types of potential geologic hazards associated with large seismic events: 1) surficial ground rupture; 2) seismically induced landslides; 3) liquefaction; and 4) ground motion. The potential for each of these hazards to adversely impact the proposed project is discussed below. 6.1 Surficial Ground Rupture The nearest known fault trace to the project site is the Seattle Fault. The southern edge of this fault zone is located approximately 5 miles to the north. Recent studies by the U.S. Geological Survey (USGS) (e.g., Johnson et al., 1994, Origin and Evolution of the Seattle Fault and Seattle Basin, Washington, Geology, v. 22, pp. 71-74; and Johnson et al., 1999, Active November I 2, 2007 ASSOCIATED EARTH SCIENCES, INC. SGBIIJ -KE04766BI -Projtas\20040766IKE\WP Page 11 Rosemont-East Renton Property King County, Washington Subswface Exploration, Geologic Hazard, and Geotechnical Engineering Report Geologic Hazards and Mitigations Tectonics of the Seattle Fault and Central Puget Sound Washington -Implications for Eanhquake Hazards, Geological Society of America Bulletin, July 1999, v. Ill, n. 7, pp. 1042-1053) have provided evidence of surficial ground rupture along a northern splay of the Seattle Fault. The recognition of this fault splay is relatively new and data pertaining to it are limited with the studies still ongoing. According to the USGS studies, the latest movement of this fault was about 1, 100 years ago when about 20 feet of surficial displacement took place. This displacement can presently be seen in the form of raised, wave-cut beach terraces along Alki Point in West Seattle and Restoration Point at the south end of Bainbridge Island. The recurrence interval of movement along these fault systems is still unknown, although it is hypothesized to be in excess of several thousand years. Due to the suspected long recurrence interval and distance from the site, the potential for surficial ground rupture is considered to be low during the expected life of the proposed structures. 6.2 Seismically Induced Landslides The site contains moderate slopes, especially along the western edge of the proposed development area. However, none of the slopes appear to exceed the King County criteria for steep slopes of greater than 40 percent inclination. Where these slopes contain fill, colluvium, and recessional outwash, the risk of landsliding, especially during seismic shaking, is generally moderate. However, provided loose soil and colluvium are removed during site grading and our recommendations for keying and benching any new fill into the existing slopes are followed, it is our opinion that the risk of slope instability will be mitigated. Where till or advance outwash underlie the moderately inclined slopes, the risk of landsliding is considered low. 6.3 Liquefaction The till and advance outwash generally have a low potential for liquefaction due to the dense state of the material. However, where saturated recessional outwash or loose fill occur, the liquefaction hazard is higher. These areas of the site are limited in aerial extent and thickness. In order to mitigate this hazard, the existing fill should be removed from the proposed construction area and new slope or detention pond berm fill should be properly keyed and benched into suitable native bearing soils. 6.4 Ground Motion The guidelines presented in the 2006 International Building Code (IBC) Section 1613 should be used in the seismic design of the project. The USGS Earthquake Hazards Program web site (http://earthquake.usgs.gov/hazmaps/) was used to determine interpolated probabilistic ground motion values in percent of gravity (g) for an event with a return period of 2 percent exceedance in 50 years. Using the web site, the prqject area was submitted using latitude and longitude for mapped spectral accelerations of S, = 1.22 for short periods (0.2 seconds) and S 1 November 12, 2007 ASSOCIATED EARTH SCIENCES, INC. SGBhs -KEJJ4766BI -Project1\20040766IKE\WP Page 12 Rosemom-East Remon Propeny King County, Washington Subsurface Exploration, Geologic Hazard, and Geotechnical Engineering Repon Geologic Hazards and Mitigations = 0.47 for a I-second period. Based on the results of our subsurface exploration and our estimation of soil properties at depth utilizing available geologic data, Site Class "C" in conformance with Table 1613.5.2 of the IBC may be used. 7.0 EROSION HAZARDS AND MITIGATIONS As of October I, 2006, the Washington State Department of Ecology (Ecology) Construction Storm Water General Permit (also known as the National Pollutant Discharge Elimination System [NPDES] permit) requires weekly Temporary Erosion and Sedimentation Control (TESC) inspections for all sites I or more acres in size that discharge storm water to surface waters of the state. The TESC inspections must be completed by a Certified Erosion and Sediment Control Lead (CESCL) for the duration of the construction. TESC reports do not need to be sent to Ecology, but should be logged into the project Storm Water Pollution Prevention Plan (SWPPP). If the project does not require a SWPPP, the TESC reports should be kept in a file on-site, or by the permit holder if there is no facility on-site. Ecology also requires weekly turbidity monitoring by a CESCL of storm water leaving a site for all sites 5 acres or greater. Ecology requires a monthly summary report of the turbidity monitoring results (if performed) signed by the NPDES permit holder. If the monitored turbidity equals or exceeds 25 nephelometric turbidity units (NTU) (Ecology benchmark standard), the project best management practices (BMPs) should be modified to decrease the turbidity of storm water leaving the site. Changes and upgrades to the BMPs should be continued until the weekly turbidity reading is 25 NTU or lower. If the monitored turbidity exceeds 250 NTU, the results must be reported to Ecology within 24 hours and corrective action taken. Daily turbidity monitoring is continued until the corrective action lowers the turbidity to below 25 NTU. In order to meet the current Ecology requirements, a properly developed, constructed, and maintained erosion control plan consistent with the local King County standards and best management erosion control practices will be required for this project. AES! is available to / assist the project civil engineer in developing site-specific erosion control plans. Based on past experience, it will be necessary to make adjustments and provide additional measures to the TESC plan in order to optimize its effectiveness. Ultimately, the success of the TESC plan depends on a proactive approach to project planning and contractor implementation and maintenance. The erosion hazard of the site soils is high. The most effective erosion control measure is the maintenance of adequate ground cover. Maintaining cover measures atop disturbed ground provides the greatest reduction to the potential generation of turbid runoff and sediment transport. During the local wet season (October I" through March 31 "), exposed soil should not remain uncovered for more than 2 days unless it is actively being worked. Ground cover measures can include erosion control matting, plastic sheeting, straw mulch, crushed rock or recycled concrete, or mature hydroseed. November 12, 2007 ASSOCIATED EARTH SCIENCES, INC. SGBIIJ -KE04766BJ -Projects\20040766IKE1WP Page 13 Rosemont-East Renton Property King Cowity, Washington Subswface Exploration, Geologic Hazard, and Geotechnical Engineering Repon Geologic Hazards and Mitigations Flow control measures are also essential for collecting and controlling the site runoff. Flow paths across slopes should be kept to less than 50 feet in order to reduce the erosion and sediment transport potential of concentrated flow. Ditch/swale spacing will need to be shortened with increasing slope gradient. Ditches and swales that exceed a gradient of about 7 to 10 percent, depending on their flow length, should have properly constructed check dams installed to reduce the flow velocity of the runoff and reduce the erosion potential within the ditch. Flow paths that are required to be constructed on gradients between 10 to 15 percent should be placed in a riprap-lined swale with the riprap properly sized for the flow conditions. Flow paths constructed on slope gradients steeper than 15 percent should be placed in a pipe slope drain. AESI is available to assist the project civil engineer in developing a suitable erosion control plan with proper flow control. Some fine-grained surface soils are the result of natural weathering processes that have broken down parent materials into their mineral components. These mineral components can have an inherent electrical charge. Electrically charged mineral fines will attract oppositely charged particles and can combine (flocculate) to form larger particles that will settle out of suspension. The sediments produced during the recent glaciation of Puget Sound are, however, most commonly the suspended soils that are carried by site storm water. The fine-grained fraction of the glacially derived soil is referred to as "rock flour," which is primarily a silt-sized particle with no electrical charge. These particles, once suspended in water, may have settling times in periods of months, not hours. Therefore, the flow length within a temporary sediment control trap or pond has virtually no effect on the water quality of the discharge since it is not going to settle out of suspension in the time it takes to flow from one end of the pond to the other. Reduction of turbidity from a construction site is almost entirely a function of cover measures and flow control. Temporary sediment traps and ponds are necessary to control the release rate of the runoff and to provide a catchment for sand-sized and larger soil particles, but are very ineffective at reducing the turbidity of the runoff Silt fencing should be utilized as buffer protection and not as a flow-control measure. Silt fencing is meant to be placed parallel with topographic contours to prevent sediment-laden runoff from leaving a work area or entering a sensitive area. Silt fences should not be placed to cross contour lines without having separate flow control in front of the silt fence. A swale/berm combination should be constructed to provide flow control rather than let the runoff build up behind the silt fence and utilize the silt fence as the flow-control measure. Runoff flowing in front of a silt fence will cause additional erosion and usually will cause a failure of the silt fence. Improperly installed silt fencing has the potential to cause a much larger erosion hazard than if the silt fence was not installed at all. The use of silt fencing should be limited to protect sensitive areas, and swales should be used to provide flow control. November I 2, 2007 ASSOCIATED EARTH SCIENCES, INC. SGBIIS-KE04766BJ -Projeml200407661KE1WP Page 14 ) Rosemont-East Renton Property King County, Washington 7. I Erosion Hazard Mitigation Subsurface Exploration, Geologic Hazard, and Geotechnical Engineering Repon Geologic Hazards and Mitigations To mitigate the erosion hazards and potential for off-site sediment transport, we would recommend the following: 1. The winter performance of a site is dependent on a well-conceived plan for control of site erosion and storm water runoff. It is easier to keep the soil on the ground than to remove it from storm water. The owner and the design team should include adequate ground cover measures, access roads, and staging areas in the project bid to give the selected contractor a workable site. The selected contractor needs to be prepared to implement and maintain the required measures to reduce the amount of exposed ground. A site maintenance plan should be in place in the event storm water turbidity measurements are greater than the Ecology standards. 2. All TESC measures for a given area to be graded or otherwise worked should be installed prior to any activity within an area other than installing the TESC features or timber harvesting. The recommended sequence of construction within a given area after timber harvesting would be to install sediment traps and/or ponds and establish perimeter flow control prior to starting mass grading. 3. During the wetter months of the year, or when large storm events are predicted during the summer months, each work area should be stabilized so that if showers occur, the work area can receive the rainfall without excessive erosion or sediment transport. The required measures for an area to be "buttoned-up" will depend on the time of year and the duration the area will be left unworked. During the winter months, areas that are to be left unworked for more than 2 days should be mulched or covered with plastic. During the summer months, stabilization will usually consist of seal-rolling the subgrade. Such measures will aid in the contractor's ability to get back into a work area after a storm event. The stabilization process also includes establishing temporary storm water conveyance channels through work areas to route runoff to the approved treatment facilities. 4. All disturbed areas should be revegetated as soon as possible. If it is outside of the growing season, the disturbed areas should be covered with mulch, as recommended in the erosion control plan. Straw mulch provides the most cost-effective cover measure and can be made wind-resistant with the application of a tackifier after it is placed. 5. Surface runoff and discharge should be controlled during and following development. Uncontrolled discharge may promote erosion and sediment transport. Under no circumstances should concentrated discharges be allowed to flow over the top of steep slopes. November 12, 2007 ASSOCIATED EARTH SCIENCES, INC. SGBlls -KE04766BI -Projtctsl20040166IKE\WP Page 15 Rosemont-East Renton Property King County, Washington Subsu,tace Exploration, Geologic Hazard, and Geotechnical Engineering Repon Geologic Hazards and Mitigations 6. Soils that are to be reused around the site should be stored in such a manner as to reduce erosion from the stockpile. Protective measures may include, but are not limited to, covering with plastic sheeting, the use of low stockpiles in flat areas, or the use of straw bales/silt fences around pile perimeters. During the period between October I" and March 31", these measures are required. 7. On-site erosion control inspections and turbidity monitoring (if required) should be performed in accordance with the Ecology requirements. Weekly and monthly reporting to Ecology should be performed on a regularly scheduled basis. TESC monitoring should be part of the weekly construction team meetings. Temporary and permanent erosion control and drainage measures should be adjusted and maintained, as necessary, at the time of construction. It is our opinion that with the proper implementation of the TESC plans and by field-adjusting appropriate mitigation elements (BMPs) during construction, as recommended by the erosion control inspector, the potential adverse impacts from erosion hazards on the project may be mitigated. November 12, 2007 ASSOCIATED EARTH SCIENCES, INC. SGB/u -KE047668/ -Projectsl200407661KElWP Page 16 Rosemont-East Renton Propeny King Co111Uy, Washington 8.0 INTRODUCTION Subsurface Exploration, Geologic Hazard, and Geotechnical Engineering Report Design Recommendations III. DESIGN RECOMMENDATIONS Our explorations indicate that, from a geotechnical standpoint, the parcel is suitable for the proposed development provided that the recommendations contained herein are properly followed. The bearing strata ranges from approximately 2 to 10 feet in depth below the ground surface across a portion of the site generally located in the northwest corner of the development area, east of the wetlands. The depth to bearing soils across the rest of the site was between about 0.5 and approximately 2 feet below existing site grades. The site soils were generally above their optimum moisture content for compaction, thus their reuse as fill during all but the driest times of the year will be difficult. In addition, many of the exploration pits encountered significant amounts of shallow ground water. The current grading plan shows new fill is to be placed above the area shown on Figure 2 containing thick, existing, uncontrolled fill soils. Since the existing fill is loose and unstable in its current condition, we recommend that the existing fill be removed within the area where new fill will be placed. As an alternative to removing and replacing the existing fill within these building lots, some type of deep foundation, such as small-diameter pipe piles (4-to 6- inch-diameter) and/or rock trenches bearing on the lower, dense, natural soils is recommended for building support throughout the previously filled portion of the site. If the deep foundation option is chosen and the new buildings will have slab-on-grade floors, we recommend that the upper 2 feet of soil below the slab subgrade elevation consist of new, compacted, free-draining structural fill. If the slabs are settlement sensitive then the floor slabs should also be pile supported. No new structural fill would be required under the floors if the buildings utilize crawl space construction techniques. In addition we recommend that the new street and driveway sections in this fill area be placed' on at least 2 feet of new. compacte.c! •. struc!.\!raUill to limit settlement differential. Conventional shallow spread footings are anticipated for the remainder of the site. Ground water was encountered in many of the explorations, especially on the north and west portions of the site. Some of the excavations for ponds, underground utilities, and general site grading are expected to encounter this ground water. The use of interceptor trenches, swales, sumps, and other methods of ground water control will therefore be necessary in areas where seepage is encountered. November 12, 2007 ASSOCIATED EARTH SCIENCES, INC. SGBIIS -KE04766BJ -Projecls\200407661KElWP Page 17 Rosemont-East Renton Property King County, Washington 9.0 SITE PREPARATION Subswface Exploration, Geologic Hazard, and Geotechnical Engineering Report Design Recommendations Any existing structures presently on the site, which are located under new construction areas, should be removed. Any buried utilities should be removed or relocated if they are also under new construction areas. The resulting depressions should be backfilled with structural fill as discussed under tbe "Structural Fill" section if they are located below new foundation or pavement areas. As noted previously, a domestic well is located on the property. If the well will not be used in the future, it should be properly abandoned. Specific standards for abandonment of wells depend on the type of well in question. Ecology presents this information in a publication entitled Minimum Standards for Construction and Maintenance of Water Wells. The water well most likely will need to be legally abandoned by a Washington State Licensed Water Well Driller. Local health district and King County regulations may also apply. Site preparation should also include removal of all vegetation. Additionally, the upper organic sod, forest duff, topsoil, and colluvium should be removed from areas to receive new fill or other improvements, and the remaining roots grubbed. Areas where loose, surficial soils exist due to grubbing and demolition operations should be considered as fill to the depth of disturbance and treated as subsequently recommended for structural fill placement. Existing deep fill within the new building footprints could be left in place provided a deep foundation system is used to support the structure and no highly organic areas, areas of demolition waste, or other adverse materials or conditions are encountered when topsoil stripping is completed. Removal of shallow obstacles to facilitate pile driving is expected to be possible with a backhoe. 9. I Temporary Cut Slopes In our opinion, stable construction slopes should be the responsibility of the contractor and should be determined during construction. For estimating purposes, however, temporary, unsupported cut slopes can be planned at lH:IV (Horizontal:Vertical) or flatter in the lodgement till and I. SH: IV in the unsaturated advance and recessional outwash deposits and existing fill. Where loose, saturated soil is present, shoring or flatter slope angles may be necessary These slope angles are for areas where ground water seepage is not encountered, and assume that surface water is not allowed to flow across the temporary slope faces. If ground or surface water is present when the temporary excavation slopes are exposed, flatter slope angles will be required. As is typical with earthwork operations, some sloughing and raveling may occur and cut slopes may have to be adjusted in the field. In addition, WISHA/OSHA regulations should be followed at all times. November 12, 2007 ASSOCIATED EARTH SCIENCES, INC. SGBIU -KE1)4!66BI -Projtcts\200407661 KE\ WP Page 18 Rosemom-East Re111011 Propeny King Cowtty, Washington Subsu,jace Exploration, Geologic Hazard, and Geotechnical Engineering Report Design Recommendations Permanent cut or fill slopes should not be steeper than 2H: IV. where they are not exposed to surface water. Where slopes are exposed to surface water, such as within the detention pond, they should not be steeper than 3H: IV. -- 9.2 Site Disturbance Most of the on-site soils contain substantial fine-grained material, which makes them moisture- sensitive and subject to disturbance when wet. The contractor must use care during site preparation and excavation operations so that the underlying soils are not softened. If disturbance occurs, the softened soils should be removed and the area brought to grade with structural fill. 9. 3 Winter Construction Due to the high in situ moisture content of most of the site soils determined by laboratory testing completed for this study, it will be necessary to dry some of the site soils during favorable dry weather conditions to allow reuse in structural fill applications. If construction takes place in winter, drying is not expected to be feasible, and we anticipate that most of the lodgement till soils and potentially some of the outwash soils will be unsuitable for structural fill applications. Even during dry weather, site soils excavated for installation of buried utilities might not be suitable for utility backfill under paving or other structures. We recommend budgeting for backfill of buried utility trenches in structural areas with imported select structural fill. For summer construction, significant but unavoidable effort may be needed to scarify, aerate, and dry site soils that are above optimum moisture content to reduce moisture content prior to compaction in structural fill applications. Care should be taken to seal all earthwork areas during mass grading at the end of each workday by grading all surfaces to drain and sealing them with a smooth-drum roller. Stockpiled soils that will be reused in structural fill applications should be covered whenever rain is possible. If winter construction is expected, crushed rock fill could be used to provide construction staging areas. The stripped subgrade should be observed by the geotechnical engineer and should then be covered with a geotextile fabric such as Mirafi 500X or equivalent Once the fabric is placed, we recommend using a crushed rock fill layer at least 10 inches thick in areas where construction equipment will be used. If desired, planned roadways can be paved with asphalt treated base (ATB) for construction staging as described in the "Pavement Recommendations" section of this report. November 12, 2007 ASSOCIATED EARTH SCIENCES, INC. SGBHs -KE04766Bl -Projeml20040766[KE\WP Page 19 Soi( frop•~rh~s ( s+~(,(~~J Rosemont-East Remon Property King County, Washington 10.0 STRUCTURAL FILL Subsurface Exploration, Geologic Hazard, and Geotechnical Engineering Report Design Recommendations Significant structural fills are currently planned for this site. All references to structural fill in this report refer to subgrade preparation, fill type, placement, and compaction of materials as discussed in this section. If a percentage of compaction is specified under another section of this report, the value given in that section should be used. All structural fill placed on slopes steeper than 5H: IV should be keyed and benched into suitable underlying native soils. Hillside benches should be 3 feet or less in height, and are usually about the width of the bulldozer used to cut them (about 6 to 8 feet). The shear key at the toe should be at least 8 feet wide and 3 feet deep. Keying and benching should be done in accordance with Washington State Department of Transportation (WSDOT) Standard Specification Section 2-03. 3. Site soils consisting of lodgement till or advance outwash or imported granular fill approved by the geotechnical engineer should be used for construction of fill slopes. The existing, uncontrolled fill soils identified near the northwest corner of the proposed development area should be completely removed prior to constructing any new structural fills or permanent cut slopes steeper than 3H:IV. After stripping, planned excavation, and any required overexcavation have been performed to the satisfaction of the geotechnical engineer/engineering geologist, the upper 12 inches of exposed ground should be recompacted to 90 percent of ASTM:D 1557. If the subgrade contains too much moisture, adequate recompaction may be difficult or impossible to obtain and should probably not be attempted. In lieu of recompaction, the area to receive fill should be blanketed with washed rock or quarry spalls to act as a capillary break between the new fill and the wet subgrade. Where the exposed ground remains soft and further overexcavation is impractical, placement of an engineering stabilization fabric may be necessary to prevent contamination of the free-draining layer by silt migration from below. After recompaction of the exposed ground is tested and approved, or a free-draining rock course is laid, structural fill may be placed to attain desired grades. Structural fill is defined as non-organic soil, acceptable to the geotechnical engineer, placed in maximum 8-inch loose lifts with each lift being compacted to 95 percent of ASTM:D 1557. In the case of roadway and utility trench filling, the backfill should be placed and compacted in accordance with King County codes and standards. The top of the compacted fill should extend horizontally outward a minimum distance of 3 feet beyond the location of the perimeter footings or roadway edges before sloping down at a maximum angle of 2H: l V. The contractor should note that any proposed fill soils must be evaluated by AES! prior to their use in fills. This would require that we have a sample of the material at least 72 hours in advance to perform a Proctor test and determine its field compaction standard. We have completed three such tests on representative samples of the site soils and the results are included in this report. Soils in which the amount of fine-grained material (smaller than the November 12, 2007 ASSOCJATED EARTH SCIENCES, INC. SGB!u-KE.0476681 -Projtcts\20040766IKEIWP Page 20 Rosemont-East Renton Property King Coumy, Washington Subsuiface Exploration, Geologic Hazard, and Geotechnical Engineering Report Design Recommendations No. 200 sieve) is greater than approximately 5 percent (measured on the minus No. 4 sieve size) should be considered moisture-sensitive. Each of the three main soil types observed on- site, the recessional outwash, lodgment till, and advance outwash, all are estimated to contain more than 5 percent fine-grained material. Use of moisture-sensitive soil in structural fills should be limited to favorable dry weather and dry subgrade conditions. The on-site advance and recessional outwash deposits contain smaller amounts of silt and are considered suitable for use as fill material under a wider range of site and soil moisture conditions. The on-site lodgment till contains substantial amounts of silt and are considered highly moisture-sensitive when excavated and used as fill materials. At the time of our exploration program, soil moisture content tests indicated that some till soils encountered were at moisture conditions above optimum for structural fill use. We anticipate that most excavated lodgment till soils will require aeration and drying prior to compaction in structural fill applications. However, the outwash materials may be adequate for use as structural fill during summer months without significant aeration. Construction equipment traversing the site when the soils are wet can cause considerable disturbance. If fill is placed during wet weather or if proper compaction cannot be obtained, a select import material consisting of a clean, free-draining gravel and/or sand should be used. Free-draining fill consists of non-organic soil with the amount of fine-grained material limited to 5 percent by weight when measured on the minus No. 4 sieve fraction and at least 25 percent retained on the No. 4 sieve. 11.0 FOUNDATIONS Due to the presence of loose fill soil below the proposed buildings in portions of the site, we recommend that they be supported on a deep foundation system that bears on suitable, native soils at depth if the fill will not be removed during grading. We anticipate that deep foundation systems may be required in the vicinity of proposed Lots 75 through 80 or other areas when the existing fill is too deep to extend footings and stem wells and will not be removed. Conventional spread footings are anticipated for the remainder of the site, where existing fills are not present or are thin enough that foundations can be excavated to suitable bearing soil through the fill. It should be understood that unless all of the loose, existing fill is removed, the risk of slope instability and liquefaction (lateral spreading) will not be completely mitigated. However, the risk of these hazards affecting the new buildings is low if they are founded in accordance with our recommendations. Table 2 presents depths to bearing soils for all explorations completed. We did not provide the bearing soil elevation because the locations of our exploration pits were not surveyed and assumed elevations may not be accurate. November 12, 2007 ASSOCIATED EARTH SCIENCES. INC. SGBlls-KE0476681 -Pro}tcts\200407661KE\WP Page 21 Rosemont-East Renton Property King County, Washington 11.1 Deep Foundations Table 2 Subswface Exploration, Geologic Hazard, and Geoteclmical Engineering Repon Design Recommendations Depth to Exploration Bearing Soil Pit (feet) Year -2007 EB-I 5.0 EB-2 5.0 EB-3 2.5 EP-1 2.0 EP-2 1.5 EP-3 3.0 EP-4 4.0 EP-5 3.0 EP-6 2.5 EP-7 2.5 EP-8 1.0 EP-9 1.0 EP-10 1.0 EP-11 1.0 EP-12 0.5 Year -2004 EP-2 I 2.5 EP-3 I 3.0 Year -2003 EP-11 8.0 EP-12 10.0 EP-13 4.0 EP-14 1.0 EP-15 3.0 EP-16 0.5 EP-17 4.0 EP-18 2.0 EP-19 1.0 EP-20 1.0 EP-21 1.0 EP-22 1.0 Two alternatives for deep foundation systems are recommended. Rock trenches could be used in areas where existing fills are no greater than 8 feet deep. Pipe piles could be used where fills are deeper than 8 feet. November 12, 2007 ASSOCIATED EARTH SCIENCES, INC. SGBhr-KE04766BI -Projtcts1200407661KE\WP Page 22 Rosemont-East Renton Property King Counl)I, Washington Pipe (Pin Piles) Subsu,face Exploration, Geologic Hazard, and Geotechnical Engineering Report Design Recommendations Small-diameter pipe (pin) piles consisting of thick walled, 4-inch-diameter, steel pipe driven by a hydraulic impact hammer mounted on an excavator or similar equipment are recommended. The 4-inch-diameter is recommended to add a degree of lateral support to the foundation system as piles will be located in moderately sloping fill soils. Pipes are typically provided in 10-foot sections and joined as needed with slip-or swage-fit couplers that are suitable for transmission of vertical compressive loads. Pipe type and schedule should be determined by the structural engineer for the project. Schedule 80 is typical for these piles. The pipe piles are driven until a suitable refusal criteria or penetration rate is achieved. The pipe piles are then incorporated into a system of pile caps and/or grade beams, which together act as the foundation system. The acceptable penetration rate (refusal criteria) depends on the driving equipment used. Four-inch nominal diameter, Schedule 80, galvanized-steel pipe piles driven to refusal at least 5 feet into the bearing soils should be capable of supporting loads on the order of 10 tons pet pile. A refusal criteria of 16 seconds per inch is appropriate during sustained driving with a 850 foot-pound hydraulic hammer for 4-inch-diameter piles. Different hammer sizes/types may have different driving characteristics and refusal criteria. If an alternate hammer is used, AESI should be notified prior to pile driving activities. We estimate the specified refusal criteria will be reached within 10 to 20 feet below existing ground surface based on our explorations and reconnaissance completed for the project. Resistance to lateral loads for a pipe pile-supported foundation would be provided by passive soil resistance against the grade beams, and, if necessary, using batter piles. A passive equivalent fluid equal to 150 pounds per cubic foot (pct) can be used for passive resistance to lateral loads on grade beams. Alternatively, if batter piles are used to resist lateral loads, the lateral resistance would be equal to the horizontal component of the axial pile load. The maximum recommended batter is 1H:4V. A structural engineer should determine the minimum spacing, location, and number of piles to be used. Pile Inspections The actual total length of each pile may be adjusted in the field based on required capacity and conditions encountered during driving and may be different than estimated above. Since completion of the pile takes place below ground, the judgment and experience of the geotechnical engineer or his field representative must be used as a basis for determining the required penetration and acceptability of each pile. Consequently, use of the presented capacities in the design requires that all piles be inspected by a qualified geotechnical engineering or engineering geologist from our firm who can interpret and collect the installation data and examine the contractor's operations. AES!, acting as the owner's field November 12, 2007 ASSOCIATED EARTH SCJENCES, INC. SGB!u. KE047r,681 -Proj~e1s\20040766)KE\WP Page 23 RosemonJ-East Renton Property King Counl)', Washington Subsurface Exploration, Geologic Hazard, and Geotechnical Engineering Report Design Recommendations representative, would determine the required lengths of the piles and keep records of pertinent installation data. A final summary report would then be distributed following completion of pier or pile installation. As part of the foundation system design, a qualified structural engineer would determine the number of piles required and the minimum spacing between adjacent piles. We recommend that 10 percent of the piles, selected at random, be load tested to verify that the selected refusal criteria are appropriate, and that the assumed axial compressive capacity has been achieved. A dial gauge or other suitable instrument that is capable of measuring pile head displacements to 0.001 inch of accuracy should be used during load tests. Loads should be applied in increments of 25 percent of design load, beginning with 25 percent and increasing to 150 percent. Each load should be held for at least 5 minutes, or until pile movement has stopped, at the discretion of the geotechnical engineer. The maximum load should be held for at least 15 minutes. Excessive displacement or creep of the pile during load testing are grounds for rejection of the pile. Rejected piles may be spliced and re-driven, replaced, or assigned a lower allowable capacity. Pile installation and load tests should be performed by the contractor, and observed by AES! to record pile lengths, driving resistance, and load test performance. Rock Trenches In areas where the fill soils are considered too deep to economically extend the footings down to suitable bearing, but are less than 8 feet deep, rock trenches extended down to the medium dense to dense, natural soils can be used for foundation support. The trenches should have a minimum width of 4 feet (or as determined by the geotechnical engineer or his representative) and be excavated down to the medium dense to dense, narural soils. Because of the potential for caving, the acrual trench width may be greater than specified. It would be appropriate to backfill the trenches as the excavation proceeds to reduce caving. The use of a larger, track-mounted backhoe will greatly speed trench excavation over the use of a conventional rubber-tired backhoe. In order to reduce disturbance of the bearing soils exposed in the trench, we recommend that the teeth of the backhoe bucket be covered with a digging plate. To determine when suitable bearing has been achieved and to verify proper rock placement, the AES! representative must be present on a full-time basis during rock trench excavation and backfill. A pump may be required to control seepage so that the bearing level can be visually determined. Seepage entering the excavation on an overnight basis must be removed prior to commencing trench excavation the following day. November 12, 2007 ASSOCIATED EARTH SCIENCES, INC. SGB//s -KE0476681-Projw1\20040766]K£\WP Page 24 Rosemont-East Renton Property King County, Washington Subswface Exploration, Geologic Hazard, and Georechnical Engineering Report Design Recommendations After the bearing stratum has been reached, the trench should be immediately backfilled. We recommend the use of quarry spalls or 2-to 4-inch size crushed rock for backfill. The crushed rock must be tamped into place to achieve a tightly packed mass; this may be done with either a "Hoepac" type compactor mounted on the excavator or more typically, with the bucket of the excavator itself. Staging areas should be maintained so that that rock is not contaminated by mud prior to placement in the trench. Equipment access to trench locations should also be maintained. Spread footings may then be used for building support when placed over properly constructed rock trenches that bear on medium dense to dense, natural soils. Footings which bear on approved rock trenches may be designed for an allowable bearing pressure of 3,000 pounds per square foot (psf) including both dead and live loads. An increase of one-third may be used for short-term wind or seismic loading. However, all rock trenches must penetrate to the prescribed bearing stratum and no trenches should be founded in or above loose, organic, or existing fill soils. In addition, all footings must centered over the trenches and have a minimum of 14 inches for one-story structures, 16 inches for two-story structures, and 18 inches for three-story structures. Anticipated settlement of footings founded on approved rock trenches should be on the order of 1 inch. However, disturbed material not removed from footing trenches prior to footing placement could result in increased settlements. All footing areas should be inspected by AESI prior to placing concrete to verify that the rock trenches are undisturbed and construction conforms with the recommendations contained in this report. Such inspections may be required by the governing municipality. Perimeter footing drains should be provided as discussed und_er the section on "Drainage Considerations." 11.2 Shallow Foundations In areas where existing fill is thin or absent, or where ex1stmg fill is removed and new structural fill pads are properly constructed, shallow spread footings may be utilized for building support when founded either directly on the medium dense to very dense, natural glacial sediments, or on structural fill placed over these materials. Natural sediments suitable for foundation support were generally encountered in our explorations at depths of approximately 0.5 to 2 feet, except in those areas described above where existing fill occurred. F9r footings founded either directly upon the medium dense to dense, natural sediments or on structural fill placed over these materials, we recommend that an allowable foundation soil bearing pressure of 3,000 psf be utilized for design purposes, including both dead and live loads. An increase of one-third may be used for short-term wind or seismic loading. Perimeter footings for the proposed buildings should be buried a minimum of 18 inches into the surrounding soil for frost protection. Interior footings should be buried a minimum of 12 inches. All footings must penetrate to the prescribed stratum and no footings should be November 12, 2007 ASSOCIATED EARTH SCIENCES, INC. SGBlts -KE0476681 -Proj,cu\20Q40766IK£1WP Page 25 Rosemont-East Re11ton Property King County, Washington S11bs111face Exploration, Geologic Hazard, and Geotechnical Engineering Repon Design Recommendations founded in or above loose or organic soils. All footings should have a minimum width of 14 inches for one-story structures, 16 inches for two-story structures, or 18 inches for three-story structures. It should be noted that the area bounded by lines extending downward at IH:IV from any footing must not intersect another footing or intersect a filled area that has not been compacted to at least 95 percent of ASTM:D 1557. In addition, a l.5H:JV line extending down from any footing must not daylight because sloughing or raveling may eventually undermine the footing. Thus, footings should not be placed near the edge of steps or cuts in the bearing soils. Anticipated settlement of footings founded as . described above should be on the order of l4 inch. However, disturbed soil not removed from footing excavations prior to footing placement could result in increased settlements. All footing areas should be inspected by AES! prior to placing concrete to verify that the design bearing capacity of the soils has been attained and that construction conforms to the recommendations contained in this report. Such inspections may be required by King County. Perimeter footing drains should be provided as discussed under the section on "Drainage Considerations." 12.0 LATERAL WALL PRESSURES All backfill behind walls or around foundation units should be placed as per our recommendations for structural fill and as described in this section of the report. Horizontally backfilled walls that are free to yield laterally at least 0.1 percent of their height may be designed using an equivalent fluid equal to 35 pcf. Fully restrained, horizontally backfilled rigid walls that cannot yield should be designed for an equivalent fluid of 50 pcf. If roadways, parking areas, or other areas subject to vehicular traffic are adjacent to walls, a surcharge equivalent to 2 feet of soil should be added to the wall height in determining lateral design forces. Walls that retain sloping backfill at a maximum angle of 2H:IV should be designed using an equivalent fluid pressure of 55 pcf for yielding conditions or 75 pcf for fully restrained conditions. As required by the 2006 !BC, retaining wall design should include a seismic surcharge pressure in addition to the equivalent fluid pressures presented above. Considering the site soils and the recommended wall backfill materials, we recommend a seismic surcharge pressure of 4H and SH psf where H is the wall height in feet, for the "active" and "at-rest" loading conditions, respectfully. The seismic surcharge should be modeled as a rectangular distribution with the resultant applied at the mid-point of the wall. November J 2, 2007 ASSOCIATED EARTH SCIENCES, INC. SGBIII -KE047668/ -ProjeCISl20040766)KE\WP Page 26 Rosemon1-East Renton Property King County, Washington Subswface Exploration, Geologic Hazard, and Geotechnical Engineering Repon Design Recommendations The lateral pressures presented above are based on the conditions of a uniform horizontal backfill consisting of the on-site, natural glacial sediments, or imported sand and gravel compacted to 90 percent of ASTM:D 1557. A higher degree cif compaction is not recommended as this will increase the pressure acting on the wall. It is imperative that proper drainage be provided so that hydrostatic pressures do not develop against the walls. This would involve installation of a minimum I-foot-wide blanket drain to within 1 foot of finish grade for the full wall height using imported washed gravel against the walls. A prefabricated drainage mat is not an acceptable substitute for the gravel blanket drain. 12.1 Passive Resistance and Friction Factors Lateral loads can be resisted by friction between the foundation and the natural glacial soils or supporting structural fill soils, or by passive earth pressure acting on the buried portions of the foundations. The foundations must be backfilled with structural fill and compacted to at least 95 percent of the maximum dry density to achieve the passive resistance provided below. We recommend the following design parameters: o Passive equivalent fluid = 250 pcf o Coefficient of friction = 0.35 The above values are allowable and include a safely factor of at least 1.5. 13.0 FLOOR SUPPORT Concrete, slab-on-grade floors may be used for the new buildings where the slabs are underlain by dense, natural soils or structural fill. We recommend crawl spaces and structural floors be used where foundations are supported on piles or rock trenches. If crawl space floors are used, an impervious moisture barrier should be provided above the soil surface within the crawl space. Slab-on-grade floors should be cast atop a minimum of 4 inches of pea gravel or washed crushed rock to act as a capillary break. The floors should also be protected from dampness by covering the capillary break layer with an impervious moisture barrier at least 10 mils in thickness. Floor slabs that are supported by site soils prepared in accordance with the "Site Preparation" section of this report or by structural fill should experience V2 inch or less of settlement. November 12, 2007 ASSOCJATED EARTH SCJENCES, JNC. SOB/ls -KEIJ4766BJ -Projulll20040766IKE\WP Page 27 Rosemolll-East Rell/011 Property King County, Washi11gto11 14.0 DRAINAGE CONSIDERATIONS Subswface Exploratio11, Geologic Hazard, a11d Geotec/mical Engineering Repon Design Recommendations All footing walls, basement walls, and retaining walls should be provided with a drain at the footing elevation. Drains should consist of rigid, perforated, polyvinyl chloride (PVC) pipe surrounded by washed pea gravel. The level of the perforations in the pipe should be set at the bottom of the footing at all locations and the drain collectors should be constructed with sufficient gradient to allow gravity discharge away from the buildings. In addition, all foundation walls taller than 3 feet should be lined with a minimum, 12-inch-thick, washed gravel blanket provided to within 1 foot of finish grade that ties into the footing drain. Roof and surface runoff should not discharge into the footing drain system, but should be handled by a separate, rigid, tightline drain. In planning, exterior grades adjacent to foundations should be sloped downward away from the structures to achieve surface drainage. 15.0 PAVEMENT RECOMMENDATIONS Undocumented fill materials underlie portions of the proposed improvement area. The quality of these materials was variable and observed to be relatively loose. As such, some remedial measures will be necessary for support of pavement in fill areas. We recommend that new pavement sections (including gravel base and top courses) in existing fill areas be underlain by at least 2 feet of structural fill compacted to at least 95 percent of ASTM: D 1557. The King County standard paving section for residential access streets is 2 inches of Class B asphalt concrete paving (ACP) above 4 inches of ATB. Although it is not required by King County, we recommend that A TB be placed above a 2-inch-thick layer of crushed surfacing top course (WSDOT Standard Specification 9-03.9[3)). An alternative section is 2 inches of ACP above 1.5 inches of crushed surfacing top course above 5 inches of crushed surfacing base course (WSDOT 9-03. 9[3]). All depths given are compacted depths. All paving materials, base course materials, and placement procedures should comply with suitable standard specifications, such as the Washington State Department of Transportation (WSDOI) Standard Specifications for Road, Bridge, and Municipal Construction or other suitable specifications. We understand that a pavement analysis is required for frontage improvements to 148'h Avenue SE. Soil conditions on this site are virtually identical to those documented to the south on CamWest's Shamrock Nursery development, at least adjacent to 148'" Avenue SE. Therefore, in our opinion, the pavement analysis AES! completed in 2004 is adequate for design of the new frontage improvements associated with this project. The 2004 pavement analysis and design pavement sections are included as Appendix B to this report. November 12, 2007 ASSOCIATE/] EARTH SCIENCES, INC. SGBhs-KE047668! -Projecu\20040766IKE\WP Page 28 Rosemo111-Easr Renron Property King County, Waslting1011 16.0 INFILTRATION POTENTIAL Subsurface Explormion, Geologic Hazard, and Geotechnical Engineering Report Design Recommendations The site's infiltration potential is considered to be low due the presence of a shallow ground water table and rather widespread, underlying, relatively impermeable lodgement till soils. There are small deposits of highly permeable recessional outwash and advance outwash on the site, but these deposits often contained considerable ground water and were limited in extent. Therefore, in our opinion, storm water detention is the most appropriate storm water inanagement strategy for the site. 17.0 DETENTION FACILITIES Two detention facilities are planned for the site. A detention pond is planned for the northeast corner of the northern parcel and a vault is planned near the northwest corner of the southern parcel. The current grading plan shows the base of the detention vault at Elevation 446.0. Since the location of EB-I was not surveyed, we are unsure if the base of the vault will be excavated into till or advance outwash. If outwash is encountered, the vault should be lined as discussed below for the detention pond. There appears to be at least 8 feet of separation between the proposed vault bottom elevation and current ground water elevation. However, the contractor should be prepared to de-water the excavation, if necessary. The vault foundations can be designed for an allowable foundation soil bearing pressure of 5,000 psf, including both dead and live loads. An increase of one-third may be used for short- term wind or seismic loading. The "Lateral Wall Pressures" section of this report should be referred to for detention pond cast-in-place retaining wall design. Based on the current grading plans, the construction of the pond will entail excavation to the desired pond bottom elevation and construction of perimeter fill berms along the northwest portions of the pond, transitioning to cut slopes along the southwest pond walls. Fill berm heights are expected to be on the order of 15 feet. With pond berm heights greater than 6 feet, the impoundment facility must comply with requirements for dam safety (WAC 173-175) if the storage capacity is greater than 10 acre-feet above natural ground level. The pond will be excavated into till on the east and advance outwash sand on the west, based on the soils encountered in EB-2 and EB-3. Ground water is expected to occur approximately 10 feet below the proposed base of pond elevation, as shown on Figure 3. Water stored in the pond without any form of liner would most likely migrate through the soil into the wetlands west of the pond location. A soil liner meeting the below-mentioned fill embankment specifications or a geosynthetic liner is recommended to reduce the amount of water migration through the underlying advance outwash sand. At this location, advance outwash exposed in excavations may be prone to raveling and as such the inner pond sidewalls should be graded to no steeper than 3H: l V. Exterior sides of the pond embankments November 12, 2007 ASSOCIATED EARTH SCIENCES, INC. SGBlls ¥ KE.0476681 -Prnjtm\10040766JKEIWP Page 29 Rosemoll/-East Rell/on Property King County, Washington Subswface Exploration, Geologic Hazard, and Geotechnical Engineering Repon Design Recommendations may be graded no steeper than 2H: IV unless existing fill soils are encountered within the external pond berm area. Berm construction should be entirely of properly compacted structural fill. Liner type, size, and installation should conform to the manufacturer's recommendations. Preparation for placement of structural fill for detention pond berm construction will entail excavation of the proposed fill area to firm, stable subsoil, as described in the "Site Preparation" section of this report. Perimeter pond berms should have a minimum top width of 6 feet if the berm will not be used as a perimeter roadway. Berms that will be used as access roadways should be 12 feet wide along straight sections and 15 feet wide at curves, at a minimum. A key equal to the berm width and a minimum of 3 feet deep (and extending down to medium dense, native soils) should extend below the base of the pond berm. The pond should also be equipped with an emergency overflow system that is connected to a suitable storm water disposal facility. The pond should be designed and constructed in accordance with the current KCSWDM. Fill soils for detention pond berm construction should contain a maximum of 60 percent sand, with a minimum of 30 percent silt, and nominal gravel and cobble content. The on-site till soils encountered in EB-3 meet this gradation requirement based on one sieve analysis we performed on this material. Additional sieve analyses of the proposed berm and liner fill will be required prior to construction. The fill should be placed as structural fill with a moisture content at or up to 2 percent above the optimum moisture content for compaction. The fill should be compacted by a sheepsfoot roller to a minimum of 95 percent of the ASTM:D 1557 maximum dry density, as described in the "Structural Fill" and "Site Preparation" sections of this report. Due to their high silt content, compaction of fill soils meeting the stated specification may be difficult to achieve during wet weather. In addition, persistent ground water seepage associated with flow to the adjacent wetland to the west may be encountered during berm keyway construction. Therefore, the keyway excavation may require specialized stabilization techniques in this location depending on the time of year and quantity of ground water encountered. The gradation of all detention pond berm and soil liner fill should be verified by AES! prior to its use, using appropriate laboratory testing. Keyway and berm construction and compaction should be observed and tested by the geotechnical engineer's representative. 18.0 ROCKERIES At least two short rockeries are planned along the south property line to complete grade transitions. Rockeries may be used to prevent erosion of cut slopes, however, they are not engineered structures and we strongly suggest that they not be used in place of retaining walls, especially where important facilities are adjacent to them. Buildings should be set back from rockeries so that a lH: IV line extending up from the rear base of the rockery does not intersect November /2, 2007 ASSOCIATED EARTH SCIENCES, INC. SGBhs -KE04766BI -ProjectJ\.Z00407661 KE\ WP Page 30 Rosemont-East Renton Property King County, Washington Subswface Exploration, Geologic Hazard, and Geoteclinical Engineering Repon Design Recommendations the footing. Rockery construction is an art that depends largely on the skill of the builder. We would like to point out that although rockeries are commonly used, they occasionally have difficulties and should be considered a long-term maintenance item. Care must be exercised in selecting a rock source since some of the material presently being supplied is soft and disintegrates in' a relatively short period of time. Samples of rock can be tested by AES! prior to their use in rockeries. If a rockery is specified, 4 feet high or less, it usually will not require a permit. Rockeries should not face fill soils greater than 3' feet in height. The following notes present rockery considerations. In addition, the contractor should confirm that his configuration conforms to current King County specifications. A. The base of the rockery should be started by excavating a trench to a minimum depth of 36 inches below subgrade into firm, undisturbed ground. This trench should extend a minimum of 2 feet in each direction beyond the base rocks. The trench should be backfilled to a depth of 12 inches below existing site grade with free-draining sand and gravel or crushed rock. If loose, soft, or disturbed materials exist at the base of the trench, they should be removed and replaced with free- draining sand and gravel or crushed rock. This backfill material should be placed in lifts not exceeding 8 inches in loose thickness and compacted to a minimum of 95 percent of the modified Proctor maximum density using ASTM:D 1557 as the standard. The gradation of the sand and gravel should be such that of the material passing the No. 4 sieve, not more than 5 percent by weight should be finer than the No. 200 sieve. B. The base rock should have a mm1mum width (perpendicular to the line of the rockery) of 40 percent of the height of the rockery and should be centered upon the zone of compacted structural fill. All rocks should also meet the following weight requirements: Height of Rockery Above 5 feet 5 feet or less Minimum Weight of Rock 500/2,200 pounds, graded, top/bottom rocks 500/1,000 pounds, graded, top/bottom rocks C. The rock material should all be as nearly rectangular as possible. No stone should be used which does not extend through the wall. The rock material should be hard, sound, durable, and free from weathered portions, seams, cracks or other defects. The rock density should be a minimum of 160 pcf. D. Rock selection and placement should be such that there will be minimum voids and, in the exposed face of the wall, no open voids over 8 inches across in any direction. The rocks should be placed in a manner such that the longitudinal axis of the rock will be at right angles or perpendicular to the rockery face. Each rock should be November 12, 2007 ASSOCIATED EARTH SCIENCES, INC. SGBIU -KF.0476681-Projects\1004Q7661KC\WP Page 31 Rosemont-East Renton Property King Counry, Washington Subswface Exploration, Geologic Hazard, and Geotechnical Engineering Report Design Recommendations placed so as to lock into two rocks in the lower tier. After setting each rock course, all voids between the rocks should be chinked on the back with quarry rock to eliminate any void sufficient to pass a 2-inch square probe. The rockery should be limited to 8 feet in height. E. A drain consisting of rigid, perforated, PVC pipe enclosed in a 12-inch-wide, pea gravel trench should be placed behind the lower course of rock to remove water and prevent the build up of hydrostatic pressure behind the wall. The remainder of the wall backfill should consist of quarry spalls with a maximum size of 4 inches and a minimum size of 2 inches. This material should be placed to a 12-inch minimum thickness between the entire wall and the cut material. The backfill material should be placed in lifts to an elevation approximately 6 inches below the top of each course of rocks as they are placed, until the uppermost course is placed. Any backfill material falling onto the bearing surface of a rock course should be removed before the setting of the next course. F. Any asphalt paving should be sloped to drain away from the rockery. In addition, the areas above rockeries should be planted with grass as soon as possible after rockery construction to reduce erosion. 19.0 PROJECT DESIGN AND CONSTRUCTION MONITORING We are available to provide geotechnical consultation as the project design develops. We recommend that AES! perform a geotechnical review of the plans prior to final design completion. In this way, our earthwork and foundation recommendations may be properly interpreted and implemented in the design. This review is not included in our current scope of work and budget. We are also available to provide geotechnical engineering and monitoring services during construction. The integrity of the foundation depends on proper site preparation and construction procedures. In addition, engineering decisions may have to be made in the field in the event that variations in subsurface conditions become apparent. Construction monitoring services are not part of this current scope of work. If these services are desired, please let us know and we will prepare a proposal. November 12, 2007 ASSOCIATED EARTH SCIENCES, INC. SGBhs -ICE0'76681 -Projtcrs\20040766IK£\WP Page 32 Rosemont-East Renton Property King County, Washington Subsurface Exploration, Geologic Hazard, and Geotechnica/ Engineering Repon Design Recommendations We have enjoyed working with you on this study and are confident that these recommendations will aid in the successful completion of your project. If you should have any questions, or require further assistance, please do not hesitate to call. Sincerely, ASSOCIATED EARTH SCIENCES, INC. Kirkland, Washington -,<-&:atw JJ Ou-lclztwr-- susan G. Beckham, P.E. Senior Project Engineer Curtis J. Koger Curtis J. Koger, P.G., P.E.G, P.Hg. Principal Geologist/Hydrogeologist Attachments: Figure 1: Figure 2: Figure 3: Vicinity Map Site and Exploration Plan Geologic Cross Section A-A' Kurt D. Merriman, P.E. Principal Engineer Appendix A: Appendix B: Exploration Logs and Laboratory Testing Results Pavement Section Reconunendations for 148"' A venue SE November 12, 2007 ASSOCIATED EARTH SCIENCES, INC. SGBlts -KE04766BJ -Projem\200407661 KE\WP Page 33 ii f ~ i fim~"""",.;~'ili""~~~:lli™t<'~i:t',ll,Ji'.~"E§""'"~~WJ}JliiJlF\!lii/1~:"""''li!!.')<!!;;W'• ,{~ ~ll]~j :~ , , .j . ' ~ . '~·\ ""'~,~\) :·,,;:, ' : t. ~2~~',s ' ·,S:i ':.~ H~-Ii rl :;n, !:; ·1~' j : I :: ,., , '-"'--'' ,,. t:-s:<'(<";-'% .ss ':{'.~-1 13, ___ ~''" t;:: 1~,r, •·L . · r ~. ":' 51. · ... _ . .1 i -- 1~;" ;~~,!~~ ··.·'\ '· \if.)t ,/:. " •'-;.,~:II n. ~"',.·· J,J;t;}r -t:·j· .. ~ji ~,/ •.;_l I I ~~, __ ,, ~i i/ -, ,-,, '"Ld . f I< ~ ~~--1 ~£ ::n ~-; ---·---~---_____ .:_:__:..:._~-------:.!.. .. ,...::.. _j___::1 ~i ~;! ;~,! ~f':1··· ~ i \,. ":_s:__:_•..!, ::: ,-l .. .)}-·-·-·- ·;-· f: Ji, ~-·,--. -"" ~ u,~ ~ : =;I \... -.~_,;_~:: ~l -;.-e I ~= ! 'J II ~i:_--::-r~_::..,~~I! .":,. '•,;·· ~-. \.... f'.-'. ~-u. l!;,,:'.~)r \ f: ::·· ":·::/ " -··'ff~L \. )!{./-!! fJ. ,'./)' i-----·':d "":) 1 I: •.,. I •• ,., \ •::,•' ". : :a.I \~~-Ji •I>'}..';· .,/::,,./ -\," l)!:1.-.... -...... ~" ,,' :C-,, ·.!~!~.'~.:.·,•:~\/····· .. i\~i;;·jl;. >;;/•:it_:.~~l1;.f1:, \t~:,~-.. ····f·> :.•.:.; ____ L __ ... -:.c .•. ~:,n N --~·-------------~·,-_____;.:..U1.1: 1.:,,11 k-·:..-•,,.-r.~ .•. 1'\=.)i·1 --~ • r·~ 1 1 ·-....:., A ;( ]ii l;; ;: /.·"I ~t : \! ,. !-:, :~~~:~~!CL .. ::~ ..... __ :.;~~!!1. __ ::\'.'..:'.c.~ .. :J :c . ..'·:'~" ' "---.,,,, l ft _=_~ •. ,...:::a: J J :-=-, .. ![< k i'~•:·. ..... . .. : ,_):i :.:.;·i1 ;-~ ©2004Thomas8ros.Nl~_ps:.tt NO SCALE ~m;.j\,~iffflf##@'~~~g;.j4ID~iiW§i¥@$i1i~tr~~f~~~':i™},lt~~~~1*¥0.t~~itr~~~,™J:~~:M!W~~ri1~4~~r j ASsocratea r.ann :,c1ences, me. VICINITY MAP Associated Earth Sciences. • FIGURE 1 [?§ ~''. ~-'"' ~--~,.·· ROSEMONT EAST RENTON PROJECTS DATE 11/07 w -~· .. ~· ., ~ :·...:.J:o '··• " · .,. ,• '·~. KING COUNTY, WASHINGTON PROJ. NO. KED407668 I i ! l ! ! i \J--,/-. ,I 1. . __ _,----~--l .. [~~-,,-:+~~~,;"~"v-;-;i!i, __ +::~~,~~:,l:·.~-,.-~l;: • I \ \ • l / · ,/ ... .. ____ , . . I . '· \ \ I r/ --- : ,/ ... ) ! / ...... ) ':( .''.) ~-~ __ ... ___ ... ,~ : _.:: : : \ > I : ' I . I -.· / ' : / \ .', I I I I I --s-•---;--;,.1..-, : :, ) I •: L,,---~• / _,_ :.:1 /. :..--,., ·r-- . ' I · I I / ,~ _!_J / I :,..-ic ROSEMONT PROPE_Kll /. "-,. - (FORIIERLYIRONWOOb) ,a· : : . _.,. ... , ·,,: I ·1 ; ·, : 1 --f. ,-. ' , : 'f: .1/. ;,-r . ' ,-·---, ' ',:f , .. , ' ' ,./ EAST RENTON PROPERTY 1 ,. ' ' 1...,.. ... ... 'if_/ ..... '-,./ (FORMERLY ROSEMOKT) ' ' .. d . ' ,, '', ... , I 1-·l-0 -·---- r''< : t>·l,, II f---~-.,·::::!_.) ' ' ' !:" ; \ ... '· ' , \;, ,-f--.L~ '\t . ' ' c·, ~ ... _ ' / ·1:.....r-rl~:t::?:teu 1!,!;!,:-:·r, L ~: l ·!-c~'-t. ' / : •;I•' ). ' "'-• ' ' • • • =.c<a • ' ' ' ' -----------------------------------+--------------------------------------- Reference: Triad ' ' ' ' ' i Associated Eart_ h Sciences, Inc. SITE AND EXPLORATION PLAN :'1• " '\ ·'··'·'· LEGEND: 0 APPROXIMATE LOCATION OF BORING BY AESI 10/1007 TYP 0 APPROXIMATE LOCATION OF EXPLORATION PIT BY AESI 812007 TYP .6. APPROXJMA TE LOCATION OF EXPLORATION PIT BY AESI 12/2004 TYP D APPROXIMATE LOCATION OF EXPLORATION PIT BY AESI 412003 c:::J EXISTING FILL WITH APP RO XI MA TE DEPTH c:J Qva ADVANCE OUTWASH c::::l Qvr RECESSIONAL OUTWASH = Qvt TILL N A ~ ~ = FIGURE 2 OATE 11/07 i ~ (e ~ ~ ~ ROSEMONT EAST RENTON PROJECTS i ~ gs; m LE y KING couNTY, wAsH1NGTON PROJECT NO. KE040766B ·---==--==--==--==--==----------------------------------------------- I l i I ,::- w w ~ z 0 ;:: <( > w _J w A 490 470J PROPOSED GRADE 450 430J Recessional outwash (silt) v,JETLJ>J-lO 410-j -;:;;-RIN~ ] - KEY AT DEPTH 5' 390 al HORIZONTAL DISTANCE (FEET) VERTICAL EXAGGERATION= 2x - Advance outwash(sand/ al ~ ~ "' INTERIOR POND BERMS FLATTEN TO 3H: 1V MAX --------- -,-,-'Silt . -~ .=- g al .... .... A' 490 470 450 430 410 390 Associated Earth Sciences, Inc. GEOLOGIC SECTION A -A' FIGURE 3 ~ I '*'H ~ IQ! m ROSEMONT EAST RENTON PROJECTS DATE 11,07 ~ _ ~ . . KING COUNTY, WASHINGTON PROJECT NO. KE040766B B "" . ., ... "' ... PROPOSED FINISH GRAD£ (TrP) \ i \\ GRAW:l ACCE55 1 --1--Ro,wA:icm.1 ·· 60 MIL PVC TEXTURED LINER \Mni 12" SOIL COVER CXIS7lNG GROf.JNO NEW SLOPE ALL KEYWA.YAND BENCHES· iYP (irP) -~ • "'--· ~ ... ~ ... \ ow B 500 I I I-,., s a ~ I-... ~ i w cr==f"' "' ... ( ~ ~ ARMOUR EXTERIOR POND BERMS WITH 1 r OF 2x,4" QUARRY SPAU. RlPRAP ~ s:2:' ~ -----___ fl.!l'S .El: ~3 Qg_.,.... --.-:-:: --=-=-~ ~~-, :JY~,fUfi ,!4floo •. i . -~-·-----<-=-----------,'----------__,, - \ IN ITRNAL SIDE SLOPES SHALL 8£ 3: 1 BELOW £LEI/ -ISB.O (EXCEPT FOR n-1£ BF.R!J BEll'lffN CF.LLS). "" ... "' "' I ~ ,~ II HORIZCltfTAL DISTANCE (FEET) VERT1CAL EXAGGERATION,. b: ~: ,- '1 ffi li 2 Ow VASHON RECESSIONAL OUTWASH-SILT "" VASHON LODGMENT TILL-LOW PERMEABIUTY ""' VASHON ADVANCE OUTWASH • SAND ~ ---BO/ El.,___J_J_2.0 ""' NEW SLOPE FILL KEYWAY ANO BfNQiES LOW PERMEABILITY BTRUCTlJRAl. ALL • lYP SEE GEOTECHNICAL REPORT ! ~ § PONO SECT/OJ\! B-8 § ~ I : I I ; -··-ASSUMED BEARING 60IL-ELEVATION BASED ON EXPLORATION BORINGS q APPROXIMATE GROUND'NATER DEPTH AT TIME OF DRIWNG -1-1-GEOLOGICCONTACT ! Associated Earth Sciences, Inc. i !iil~~~m ·------- GEOLOGIC CROSS-SECTION B -B ROSEMONT-EAST RENTON PROPERTY KING COUNTY, WASHINGTON ~ ! ~ ~ ... q I "' .,, ,-------J ~ ElCPltES 11/'J!JID! F!GllU; 1 DATE 2108 PROJECT NO. ICE040766B MIN 4" DIA PERFORATED RIGID PVC PIPE WITH PERFORATIONS SET DOWN PROVIDE MIN 1% CONTINUOUS SLOPE TO APPROVED OUTLET 12" MINIMUM I --,, r-_1_, ORIGINAL GROUND SURFACE WASHED DRAIN ROCK FILTER FABRIC MIRAFl-140N OR EQUIVALENT WRAf' ENTIRE DRAIN WASHED DRAIN ROCK Fill I Weathered Till Gray. Non-Weathered Till Associated Earth Sciences, Inc. TYPICAL INTERCEPTOR TRENCH DETAIL FIGURE 2 & ~ ~ !\ii:] ~ li7iiffilil ROSEMONT-EAST RENTON PROPERTY DATE 2/08 i t:mJ rn ~ IE lffl KING COUNTY, WASHINGTON PROJ. NO. KE040766 A ~--------------------------------- APPENJl)KX A lExploiratiorrn Logs arrnol Lalboiratoiry Testirrng Results .i "' g N ci z • ~ • • rn Q. ~ ::, J; Well-graded gravel and GW gravel with sand, little to no fines Silty gravel and silty GM gravel with sand Clayey gravel and GC clayey gravel with sand Well-graded sand and sw sand with gravel. little to no rines Poorly-graded sand SP and sand with gravel, little to no fines Silty sand and SM silty sand with gravel SC Clayey sand and clayey sand with gravel Silt. sandy silt. gravelly silt. ML silt with sand or gravel CL Clay of low to medium plasticity; silty, sandy, or gravelly clay, lean clay Organic clay or silt of low OL plasticity Terms Describing Relative Density and Consistency Coarse· Grained Soils Density SPT12lblows/foot Very Loose O to 4 Loose 4 lo 10 Medium Dense 10 to 30· Dense 30 to 50 Very Dense > SO Test Symbols G = Grain Size Consistency SPT1'iblows/foot M = Moisture Content A = Atterberg Limits C ~ Chemical Fine· Grained Solis Very Soft O to 2 Soft 2to4 Medium Stiff 4 to B Stiff B to 15 Very Stiff 15 lo 30 Hard >30 DD -Dry Density K = Permeability Descriptive Term Boulders Component Definitions Size Range and Sieve Number Larger lhan 1T Cobbles Gravel Coarse Gravel Fine Gravel Sand Coarse Sand Medium Sand Fine Sand SUI and Clay 3" lo 12" 3' to No. 4 (4. 75 mm) 3" to 3/4' 3/4" lo No. 4 (4.75 mm} No. 4 (4.75 mm) to No. 200 (0.075 mm} No. 4 (4.75 mm) to No. 10 (2.00 mm) No. 10 (2.00 mm) to No. 40 (0.425 mm) No 40 (0.425 mm) to No. 200 (O 075 mm) Smaller lhan No. 200 (0.075 mm) <3 ) Estimated Percentage Moisture Content Ory -Absence of moisture, dusty, dry to the touch Slightly Moist -Perceptible moisture Trace Few Little With Sampler Type Percentage by Weight <5 5 to 10 15to25 • Non-primary coarse constituents: ~ 15% -Fines conlent between 5%and 15% Moist -Damp bul no visible water Very Moist -WalB! visible but not free draining Wet -Visible free water, usually from below waler table Symbols Btows/6" or portion of 6" Cement grOul surface seal Elastic silt, clayey si , silt 2.0" 00 MH with micaceous or I • • • Sampler Type Description Benlonite sear Split-Spoon diatomaceous fine sand or Sampler 3.0' OD Split-Spoon Sampler --+2sillilt _______ --J (SPT) Clay of high plasticity, sandy or gravelly clay, fat clay wilh sand or gravel 3 25' 00 Split-Spoon Ring Sampler ·._ FIiier pack with :':· blank casin{;I :-· section Bulk sample CH 3.0' OD Thin-Wall Tube Sampler Oncludlng Shelby tube) :.-Screened casing . -· or Hydrotlp ·.-wllh fitter pack ·. Endcap ,f---,1----------1 Grab Sample Organic clay or silt ot O Portion no! recovered OH medium 10 high 111 Percentage by dry weight £-:f---1-p-la_s_tic_i_ty ______ -l (21 (SPT) Standard Penetration Test (ASTM D-1586) Peat, muck and other (Jl ln General Accordance with PT highly organic soils Standard Practice far Description and ldenlification al Soils (ASTM 0~2488) 141 Depth of ground water :'g. ATD -Al time of drilling ~ Static water level (date) (5) Combined USCS symbols used for fines between 5% and 15% ! Classifications of sells In lhls report are based on vlsual field and/or laboratory observaUons, which lndude density/consistency, moisture condition, grain size, and plasticity eslimates and should not be construed lo imply field or laboratory testing unless presenled herein. Vlsual-manual and/or laboratory classificallon ~ methods of ASTM D-2487 and 0-2488 were used as an identification guide for lhe Unified Soil Classification System. n ~ Associated Earth Sciences, Inc. i•~lililli EXPLORATION LOG KEY FIGURE A1 1 - 2 3 - 4 5 - 6 7 8 - 9 - 10 - 11 - 12 - 13 - 14 - 15 - 16 - 17 · 18 · 19 · LOG OF EXPLORATION PIT NO. EP-1 This log Is part of the report prepared by Associated Earth Sciences, Inc. (AESI) for the named project and should be read together with that report for complete interpretation. This summary applies only to the location of lhis trench at the time of excavation. Subsurface condilions may change at this location with the passage of time. The data presented are a simplflcation of actual conditions encountered. DESCRIPTION Brush and Topsoil Organic FIii Moist to dry, dark brown, silty fine to medium SAND, with gravel and roots and organics. (SM) Vashon Lodgement Till Medium dense grading to dense at 3 feet, moist, mottled brown-gray, silty fine to medium SAND, with gravel and cobbles; gray and very dense with no mottling below 3.5 feet. (SM) Bottom of exploration pit at depth 4 feet No ground water. No caving. ij _______________________________ _ o/ I Rosemont-East Renton Property King County, WA- ~ Associated Earth Sciences, Inc. Project No. KE040766B ! Logged by: SGB Approved by 1:~j I 'r"il f\iJ ~ ~"';3 7/15/07 ~----------------~-------------------------- g i Cl 1 - 2 - 3 - 4 - LOG OF EXPLORATION PIT NO. EP-2 This log is part of the report prepared by Associated Earth Sciences, Inc. (AESI) for the named project and should be read together with that report for complete Interpretation. This summary applies only to the location of this trench at the time of excavation. Subsurface conditions may change at this location with the passage of time. The data presented are a slmplfication of actual conditions encountered. DESCRIPTION Brush and Topsoil Fill Medium dense, dry, dark brown, silty SAND, with organics and roots. (SM) Weathered Vashon Lodgment TIii Medium dense, moist to dry, brown, silty fine SAND, with gravel, cobbles, few roots, little cohesion. Vashon Lodgement Till 5 -Very dense, moist, gray, silty fine to medium SAND, with gravel and cobbles. (SM) 6 7 - 8 - 9 - 10 - 11 - 12 - 13 - 14 - 15 - 16 - 17 - 18 - 19 - Bottom of exploration pit at depth 6 feet No ground water-No caving ~---------------------------------" I i Rosemont-East Renton Property King County, WA Associated Earth Sciences, Inc. I Logged by: SGB Project No. KE040766B ~ Approvedby ~ I ',7,~1 ~ ~ m 7/16/07 ~------------------------------------------- LOG OF EXPLORATION PIT NO. EP-3 This log is part of the report prepared by Associated Earth Sciences, Inc. (AES!) for the named project and should be read together with that report for complete interpretation. This summary applles only to the location of this trench at the lime of excavation. Subsurface condltlons may change at this location with the passage of time. The data presented are a slmplficatlon of actual conditions encountered. DESCRIPTION Brush and Topsoil 1 -Weathered Vashon Lodgement Till Loose, moist, dry, brown, silty fine SAND, with gravel, cobbles, and roots. (SM) 2 - 3 Vashon Lodgement Till Dense to very dense, moist, gray, silty fine to medium SAND, with gravel and cobbles. (SM) 4 - 5 - 6 7 - 8 - 9 - 10 - 11 - 12 - 13 - 14 - 15 - 16 - 17 - 18 - 19 - Bollom of exploration pit at depth 6 feel No ground water. No caving. ~ .,------------------------------------------- ~z·.i Rosemont-East Renton Property ~ I M ~ Logged by: SGB Approved by: King County, WA Associated Earth Sciences, Inc. Project No. KE0407668 7/15/07 ---------------------------------- LOG OF EXPLORATION PIT NO. EP-4 §: This log Is part of the report,rrepared by Associated Earth Sciences, Inc. (AESJ) for the named ftroject and should be £ read together with that repo for comftlete Interpretation. This summary agplies only to the loca ion of this trench at the C. time of excavation. Subsurface condl Ions may change at thls location wit the passage of time. The data presenled are • 0 a simplfication of actual conditions encountered DESCRIPTION Brush and Topsoil 1 -Colluvlum Loose to medium dense, dry, brown, silty fine to medium SAND, with gravel, cobbles, roots, trace 2 -boulders. (SM) 3 - 4 Recessional Outwash 5 Medium dense, moist to dry, stratified SAND, with gravel and abundant roots. (SP) 6 -Medium dense, moist, fine to medium SAND, with silt and gravel and interbeds of silty medium to coarse SAND. (SP-SM) 7 - 8 - 9 - 10 -Becomes wet at 1 O feet. 11 - 12 Medium dense, wet, gray, medium to coarse SAND, with silt, cobbles, and gravel. (SP-SM) 13 Pre-Fraser Sedimentary Deposits (Qpf) 14 Stiff to hard, dark brown, PEAT, with gray and brown, hard silt interbeds. (PT/ML) 15 -Bottom of exploration pit at depth 14 feet Very slow ground water seepage at 10 feel. Moderate caving 5 to 13 feet. 16 - 17 - 18 - 19 - ~----------------------------------" I ~ Rosemont-East Renton Property King County, WA Associated Earth Sciences, Inc. I Logged by: 5GB Project No. KE0407668 M Approved by l:~'IJ I f';,I ~I ~ M 7/15/07 ~------------------------------------------- 1 - 2 - 3 4 - 5 - LOG OF EXPLORATION PIT NO. EP-5 This log Is part of the report prepared by Associated Earth Sciences, Inc. (AESl) for the named project and should be read together with that report for complete Interpretation. This summary applies only to the location of this trench at the time of excavation. Subsurface condilions may change at this location with the passage of lime. The data presented are a simplflcatlon of actual conditions encountered. DESCRIPTION Brush and Topsoil Weathered Vashon Lodgement TIii Loose to medium dense at 2.5 feet, dry, brown, silty fine SAND, with gravel and roots to 1 foot. (SM) Vashon Lodgement TIii Dense, moist, gray, silty fine to medium SAND, with gravel, cobbles, and few boulders. Very dense below 4 feet; mottled 3 to 4 feet. (SM) 6+------------------------------- 7 - 8 - 9 - 10 - 11 - 12 - 13 - 14 - 15 - 16 - 17 - 18 - 19 - Bottom of exploralion pit at depth 6 feet No ground water. No c9:ving. ~-------------------------"' I Rosemont-East Renton Property King County, WA ;~-Associated Earth Sciences, Inc. Project No. KE040766B !" Logged by: SGS Approvedby: Ill 1-fl'cl ~ a Ill 7/15/07 ~------------------------------------------- g ,; 0. i!l 1 - 2 - 3 . 4 - 5 - 6 - 7 a - 9 - 10 - 11 - 12 13 14 - 15 16 - 17 - 18 - 19 - LOG OF EXPLORATION PIT NO. EP-6 This log Is part of the report rfrepared by Associated Earth Sciences, Inc. (AESI) for the named ftroject and should be read togettier with that repo for com~lete Interpretation. This summary a~plles only to the loca ion of this trench at the time of excavation. Subsurface condi Ions may change at this location wit the passage of time. The data presented are a slmplflcatlon of actual conditions encountered. DESCRIPTION Brush and Topsoil Weathered Soll Loose, dry, brown, silty fine to medium SAND, with gravel, cobbles, and roots. (SM) TIii/Advance Outwash Transition Dense, moist, gray-brown, silty fine to medium SAND to SAND, with silt, little gravel. Advance Outwash Grades to very dense, wet, stratified, brown, fine SAND, wilh silt and very lhin silt, laminae to 1 mm thick spaced at approximately 1/2-inch intervals, little mottling. (SP/SM) Very dense, very moist, gray-brown, interbedded SILT and silty fine SAND, with gravel, little mottling. (MUSM) Bottom of exploration pit at depth 15 feet No ground water, but mottled throughout Rosemont-East Renton Property King County, WA 1 - 2 - 3 LOG OF EXPLORATION PIT NO. EP-7 This log ls part of the report prepared by Associated Earth Sciences, Inc. (AESI) for the named project and should be read together with that report for complete interpretation. This summary applies only lo the location of this trench at the time of excavation. Subsurface conditions may change at this location with the passage of time. The data presented are a simplflcatlon of actual conditions encountered. DESCRIPTION Brush and Topsoil Weathered Vashon Lodgement TIii Loose, dry, brown, silty fine SAND, with gravel, roots, and cobbles. (SM) Medium dense at 2.5 feet. Vashon Lodgement TIii Dense, dry, gray-brown, silty fine to medium SAND,'wlth gravel and cobbles. (SM) 4 - 5 - 6 - 7 - 8 9 - 10 - 11 - 12 - 13 - 14 - 15 - 16 - 17 - 18 - 19 - Very dense and gray below 5 feet. Bottom of exploration pit at depth 8 feet No ground water. No caving. ~---------~--------------------" I Rosemont-East Renton Property King County, WA ! Associated Earth Sciences, Inc. Project No. KE040766B : Logged by: SGB Approved by Iii I ·fhl lliiJ iii IBI 7 /15/07 ~-------------------------- 1 - 2 - 3 LOG OF EXPLORATION PIT NO. EP-8 This log Is part of the report prepared by.Associated Earth Sciences, Inc. (AESI) for the named project and should be read together with that report for complete interpretation. This summary applies only to the location of this trench at the time of excavation. Subsurface conditions may change at this location with the passage of time. The data presented are a slmp!fication of actual conditions encountered. DESCRIPTION Brush and Topsoil Weathered Vashon Lodgement TIii Loose grading to medium dense at 1 foot, dry, brown, silty fine SAND, with gravel and cobbles. (SM) Vashon Lodgement Till Dense, dry, gray-brown, silty fine to medium SAND, with gravel and cobbles. (SM) 4 - 5 6 - 7 - B - 9 - 10 - 11 - 12 - 13 - 14 - 15 - 16 - 17 - 18 - 19 - Bottom of exploration pit at depth 5 feet No ground water. No caving. ~-------------------------------------------"' ! Rosemont-East Renton Property King County, WA :;,,;: Associated Earth Sciences, Inc. Project No. KE040766B " Logged by: SGB Approved by VII I ~I ~ a 1111 7/15/07 ~------------------------ LOG OF EXPLORATION PIT NO. EP-9 This log ls part of the report prepared by Associated Earth Sciences, Inc. (AESI) for the named project and should be read together with that report for complete Interpretation. This summary applies only to the location of this trench at the time of excavation. Subsurface conditions may change at this location with the passage of time. The data presented are a slmplficatlon of actual conditions encountered. DESCRIPTION Brush and Topsoil 1 -Weathered Vashon Lodgement Till Loose grading to medium dense at 1 foot, dry to moist, brown, silty fine SAND, with gravel and 2 -roots. (SM) Vashon Lodgement Till 3 -"\Dense, gray mottled, silty fine to medium SAND, with gravel, few cobbles. (SM) 4 - 5 6 - 7 - 8 - 9 - 10 - 11 - 12 - 13 - 14 - 15 - 16 17 - 18 - 19 - Bottom of exploration pit at depth 3 feel No ground water. No caving. r ~--------------------------------" I Rosemont-East Renton Property King County, WA ~ ~ Associated Earth Sciences, Inc. § Logged by: SGB Project No. KE0407668 ~ Approvedby Iii I ·~:I Iii,;! i'il Ill 7/15/07 ~------------------------------------------ LOG OF EXPLORATION PIT NO. EP-10 This log is part of the report prepared by Associated Earth Sciences, Inc. (AESI) for the named project and should be read together with that report for complete Interpretation. This summary applies only to the location of this trench at the time of excavation. Subsurface conditions may change at this location with the passage of time. The data presented are a slmplfication of actual conditions encountered. DESCRIPTION Brush and Topsoil 1 -Weathered Vashon Lodgement Till Loose grading to medium dense at 1 foot, dry, brown, silty fine to medium SAND, with gravel, 2 -cobbles, and few roots to 1 foot. (SM) Vashon Lodgement Till 3 • Dense, moist, gray-brown mottled, silty fine to medium SAND, wilh gravel and cobbles. (SM) 4 - 5 - 6 - 7 - 8 - 9 - 10 - 11 - 12 - 13 - 14 - 15 - 16 - 17 - 18 - 19 - Bottom of exploration pit at depth 3.5 feet No ground water. No caving. ij _______________________________ _ Rosemont-East Renton Property King County, WA ii · Associated Earth Sciences, Inc. I Logged by: SGB Project No. KE0407668 ~--Ap-pr-ov_ed_b_Y' ________ 11 ___ 1~_· _.·;J_~_"_"_f&_i_iJ_· _m_:_"_··---------7-/1-5/-07- 1 - 2 - LOG OF EXPLORATION PIT NO. EP-11 This log Is part of the report prepared by Associated Earth Sciences, Inc. (AESI) for the named project and should be read togelher wilh that report for complete interpretation. This summary applies only to the tocaflon of this trench at the time of excavation. Subsurface conditions may change at this location with the passage of time. The data presented are a slmplficatlon of actual conditions encountered. DESCRIPTION Brush and Topsoil Weathered Vashon Lodgement TIii Loose grading to medium dense at 1 foot, dry, brown, silty fine to medium SAND, with gravel, cobbles, and few roots to 1 foot. (SM) Vashon Lodgement TIii 3 -Dense, moist, gray-brown mottled, silty fine to medium SAND, with gravel and cobbles. 4 - 5 - 6 - 7 - 8 - 9 - 10 - 11 - 12 - 13 - 14 - 15 - 16 - 17 - 18 - 19 - Bottom of exploration pit at depth 3.5 feet No ground water. No caving. i ______________________________ _ "' 1 Rosemont-East Renton Property King County, WA § Associated Earth Sciences, Inc, ; Logged by: SGB Project No. KE040766B Approvedby 11111,~1 hi a El 7/15/07 ~------------------------ LOG OF EXPLORATION PIT NO. EP-12 This log Is part of the report prepared by Associated Earth Science?, Inc, (AES!) for the named project and should be read together with that report for complete interpretation. This summary applies only to the location of this trench at the time of excavation. Subsurface conditions may change at this location with the passage of time. The data presented are a simplfication of actual conditions encountered. · DESCRIPTION Brush and Topsoil 1 -Weathered Vashon Lodgement T111 Medium dense, moist, gray-brown, silty fine to medium SAND, with gravel and cobbles mottled. 2 - 3+-----------~~-~~-~~------------Vashon Lodgement T111 Dense to very dense, moist, gray, silty fine to medium SAND, with gravel and cobbles. 4 +-------'--'-'--'--'-'-'---'--''----'"------'-----------'----~------------ 5 - 6 - 7 - 8 - 9 - 10 - 11 - 12 - 13 - 14 - 15 - 16 - 17 - 18 - 19 - Bottom of exploration pit at depth 4 feet No ground water. No caving. ~------------------------"' I Rosemont-East Renton Property King County, WA ! Associated Earth Sciences, Inc. Project No. KE040766B ! Logged by: SGB Approvedby: IBJ 11"1 ~ la 18 7/16/07 ~---------------------------------------- LOG OF EXPLORATION PIT NO. EP-1 This log is part of the report prepared by Associated Earth Sciences, Inc. (AES/) for the named project and should be read together with that report for complete interpretation. This summary applles only to the location of this trench at the time of excavation. Subsurface condilions may change at this location with the passage of lime. The data presented are a slmplfication of actual conditions encountered. DESCRIPTION Forest Duff Weathered Vashon Recessional Outwash 1 -Loose, moist, reddish-brown, silty fine SAND (SM); abundant roots 2 - r 3 +--------------,,v-as'h,-o-n--..R-e-ce_s_s'lo_n_a-,1·o'""u-,tw_a_s:-h------------- 4 -Medium dense, very moist, tan, silty fine SAND (SM). 5 - Vashon Advance Outwash 6 - 7 -Very dense, very moist, light brown, silty SAND with gravel (SM); scattered cobbles and boulders; 8 - 9 - 10 - 11 - 12 - 13 - · becomes wet at 11 '; contains abundant cobbles and little silt below 1 O'; increased gravel content arid moisture below 1 O'. 14 -Becomes wet again below 14'. 15 16 - 17 - 18 - 19 - Very dense, wet, light brown GRAVEL with sand, little silt (GM). ij ________________________ _ " i Rosemont-East Renton Property King County, WA § Associated Earth Sciences, Inc. I Logged by: T JP Project No. KE04766A Approved by: Im L~I ~ ~ m December 2004 ~----------------------- 21 - 22 23 - 24 - 25 - 26 27 · 28 - 29 - 30 - 31 - 32 - 33 - 34 - 35 - 36 - 37 - 38 - 39 - LOG OF EXPLORATION PIT NO. EP-1 This log is part of the report prepared by Associated Earth Sciences, Inc. (AESI) for the named project and should be read togetlier with that report for complete interpretation. This summary applies only to the location of this trench at the time of excavation. Subsuliace conditions may change at this location w!th the passage of tlma. The data presented are a slmplflcalion of actual conditions encountered. . DESCRIPTION Bottom of exploration pit at depth 22 feet Minor sloughlng below 14'. Slow, spotty seepage at 11' Moderately rapid seeping below 14'. ~---------------------------j I Logged by: T JP g Approved by: Rosemont-East Renton Property King County, WA Associated Earth Sciences, Inc. Project No. KE04766A December 2004 ~--------------------------'--------------- 1 - 2 - LOG OF EXPLORATION PIT NO. EP-2 This log Is part of the report prepared by Associated Earth Sciences, Inc (AESI) for the named projecl and should be read togetlier with that report for complete interpretation. This summary applies only to the location of this trench at the time of excavation. Subsurface conditions may change at this location wilh the passage of time. The data presented are a slmplflcation of actual conditions encountered. · DESCRIPTION Sod/ Topsoil Weathered Vashon Lodgement TIii Loose to medium dense, moist to very moist, reddish-brown, silty SAND with gravel, scattered cobbles. (SM) Becomes medium dense, very moist and tan below 2.5'. 3 - 4 - 5 - Vashon Lodgement Till 6 -Dense to very dense, very moist, grayish-tan, silty SAND with gravel, scattered cobbles. 7 - 8 - 9 - 10 - 11 - 12 - 13 - 14 - 15 - 16 - 17 - 18 - 19 - Bottom of exploration pit at depth 8.5 feet No seepage. No caving. ~--------------------------- 1 Rosemont-East Renton Property King County, WA i Associated Earth Sciences, Inc. ! ~:~:::ybyTJP llil 1 ·~1 ~ a E Project::~e::::72:: ~---------------------- LOG OF EXPLORATION PIT NO. EP-3 This log Is part of the report,prepared by Associated Earth Sciences, lnc. (AESI) for the named project and should be read together with that repo for complete interpretation. This summary applies only to the location of this trench at the time of excavation. Subsurface conditions may change at this location with the passage of time. The data presented are a stmplflcatlon of actual conditions encountered. DESCRIPTION l------l-----------------------------·----------1--1 Topsoil 1 - 2 - 3 - Weathered Vashon Lodgement TIii Loose, moist, reddish-brown, silty SAND, with gravel (SM); becomes very moist below 1.5'; becomes medium dense and tan below 3'. Vashon Lodgement TIii 4 -Very dense, very moist, grayish-tan, silty SAND with gravel, scattered cobbles. (SM) 5 - 6-1---------------~--~----------------Advance Outwash 7 -Very dense, very moist, grayish-tan, SAND with gravel, little silt. (SP) 8 - 9 - 10 - 11 - 12 -+--------------------------------- 13 - 14 - 15 - 16 - 17 - 18 - 19 - Bottom of exploration plt at depth 12 feet No seepage. No caving ~-------------------------,-; j Rosemont-East Renton Property King County, WA ; Logged by: T JP Associated Earth Sciences, Inc. Project No. KE0 4766 A § Approved by: i. ! 'f,\,! ~ aJ ffl December 2004 ~------------------------ LOG OF EXPLORATION PIT NO. EP-11 This tog is part of the report prepared by Associated Earth Sciences, 1nc. (AESI) for the named project and should be read together with that report for complete Interpretation. This summary applies only to the locallon of this trench at the time of excavation. Subsurface condlflons may change at this location with the passage of time. The data presented are a simplflcation of actual conditions encountered. DESCRIPTION t\ Sod and Topsoil 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 9 - 10 - 11 - 12 13 - 14 - 15 - 16 - 17 - 18 - 19 - FIii Loose, wet to saturated, olive-gray, dark brown, and dark gray, nonstratified, silty, fine to coarse SAND, few fine to coarse, subrounded to subangular gravel, few scattered concrete rubble and boulders to 30" in diameter, few organics. (SM) Recessional Outwash Medium dense, saturated to wet, mottled, light olive-brown, nonstratified, fine to coarse SAND, little silt, few subrounded, fine to coarse gravel, trace subrounded cobbles. (SP-SM) Bottom of exploration pit at depth 12 feet Heavy caving throughout moderate (-2 to 3 gpm) seepage below 3'. r ij _____________________________ _ • ~ Ironwood King County, WA ~ Associated Earth Sciences, Inc. ~ Logged by: JDC Project No. KE03173B § Approved by: 1B I -f~:I llt,;J IMil II April 2003 ~----------------------- LOG OF EXPLORATION PIT NO. EP-12 This log Is part of the report prepared by Associated Earth Sciences, Inc. (AES1) for the named project and should be read tqgettier wlth that report for complete lnlerpretatinn. This summary applies only to the locallon of this trench al the llme of excavation. Subsurface condilions may change at this tocat!on with the passage of time. The data presented are a slmplflcatlon of actual conditions encountered. DESCRIPTION ,"Sc,o,sdc,ae,n_,_,d,_T-"o"'m"':sc,o"'il'-------------~---c-----------------__/r FIii 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 - 10 Loose, wet to saturated, olive-gray, dark brown, and dark gray, nonstratified, silty, fine to coarse SAND, few fine to coarse, subrounded to subangular gravel, few scattered concrete rubble and boulders to 30" in diameter, few organics. (SM) Recessional Outwash Medium dense, wet, tan, weakly stratified, fine to medium SAND, trace silt. (SP) 11 - 12 13 - Bollom of exploration plrat depth 12 feet Moderate caving throughout. Very sllghl (-1gpm) seepage below 6'. 14 - 15 - 16 - 17 - 18 - 19 - 2------------------------lronwood '/! ) ? ~ ~ a ~ Logged by: JDC Approved by: King County, WA Associated Earth Sciences, Inc. ~~~~fa] Project No. KE03173B April 2003 ---------------------------------- 1 . 2 • 3 • 4 5 . 6 . 7 . 8 - 9 - 10 11 - 12 - 13 - 14 - 15 - 16 - 17 - 18 - 19 - .. LOG OF EXPLORATION PIT NO. EP-13 This log is part of the report prepared by Associated Earth Sciences, Inc. (AESIJ for the named project and should be read tqgetlier with that report for complete Interpretation. This summary applies only lo the location of this trench at the time of excavation. Subsurface condlflons may change al this locallon with the passage of time. The data presented are a slmplflcaUon of actual conditions encountered. DESCRIPTION ,,Sod and Toosoil FIii Loose, wet to saturated, olive-gray, dark brown, and dark gray, nonstratified, silty, fine to coarse SAND, few fine to coarse, subrounded to subangular gravel, few scattered concrete rubble and boulders to 30" in diameter, few organics. (SM) Recessional Outwash Medium dense, wet, tan, weakly stratified, fine to coarse SAND, little fine to coarse, subrounded to rounded gravel, trace slit. (SW) Bottom of exploratlon ptt at depth 10 feel Minor caving throughout. Slight (1 to 2 gpm) seepage below 1'. ~------------------------- Ironwood l King County, WA ~ ~ Associated Earth Sciences, Inc. Project Na. KE031 73 s S Logged by: JDC m ~ ~ ~ ~. Approved by: ~ ~ ED.'Sl L:Y41 ~ April 2003 ~-------------------- 1 - 2 . 3 - 4 - 5 - 6 - 7 - 8 - 9 - 11 12 - 13 - 14 15 - 16 - 17 - 18 - 19 - LOG OF EXPLORATION PIT NO. EP-14 This ·109 Is part of the report prepared by Associated Earth Sciences, Inc. (AESJ) for lhe named project and should be read together with that report for complete Interpretation. This summary applies only to the locaOon of this trench at the time of excavaUon. Subsurface conditions may change at this locatlon with the passage of time. The data presented are a slmplficalion of actual conditions encountered. DESCRIPTION Sod and Topsoil Recessional Outwash Medium dense, moist, Ian, weakly stratified, fine to coarse SAND, few fine lo coarse, subrounded to rounded gravel, trace roots in the upper 4'. (SW) Bottom of exploration pit at depth 10 feet Minor caving throughout. Sllght ( 1 to 2 gpm) seepage at 10'. i ______________ ,,;,,_ ______________ _ Ironwood King County, WA I ~ ~ iii g Logged by: JDC Approved by: Associated Earth Sciences, Inc. mJe~~~ Project No. KE03173B April 2003 \! __________________________________________ _ 2 - 3 4 - 5 - 6 - 7 - 8 - 9 - 11 - 12 - 13 - 14 - 15 - 16 - 17 - 18 - 19 - LOG OF EXPLORATION PIT NO. EP-15 This log ls part of the report prepared by Associated Earth Sciences, Inc. (AESI) for the named project and should be read together with that report for complete interpretation. This summary applies only to the location of this trench at the lime of excavation. Subsurface conditions may change at this location with the passage of time. The data presented are a simplfication of actual conditions encountered. DESCRIPTION Sod and Topsoil . Recessional Outwash Loose to medium dense, wet, tan, weakly stratified, sandy, fine to coarse, subrounded to rounded gravel, trace silt. (GW) Advance· Outwash Medium dense to dense, wet, mottled tan, stratified, silty, fine to medium SAND grading to hard, tan, sandy SILT. (SM/ML) Bottom of exploration pit at depth 10 feel Moderate caving throughout Heavy (5 to 10 gpm) seepage at 3' to 5'. ~-------------------------ii t 6 Ironwood King County, WA ~ Logged by: JDC Associated Earth Sciences, Inc. Project No. KE 031738 8 Approved by Id I ~I ~ iii Ill] April 2003 ~------------------------------""""------------ 1 - 2 3 LOG OF EXPLORATION PIT NO. EP-16 This log Is part of the report prepared by Associated Earth Sciences, Inc. (AESI) for the named project and should be read togeltier with that report for complete interpretation. This summary applies only to the location of this trench al the time of excavation. Subsurface conditions may change al this location with the passage of time. The data presented are a s!mplficatlon of actual conditions encountered. DESCRIPTION Sod and Topsoil Weathered TIii Dense to very dense, moist, light olive-brown, nonstratified, fine to coarse SAND, little silt, few fine to coarse, subrounded gravel, trace roots, trace subrounded cobbles. (SM) Transition to Advance Outwash Very dense, moist, light olive-gray, fine to coarse SAND, little silt, few fine to coarse, subrounded 4 · gravel, trace subrounded cobbles. (SP-SM) 5 . 6 - 7 8..1..------------------------------------- 9 10 · 11 · 12 · 13 · 14 · 15 · 16 · 17 - 18 · 19 - Bottom of exploration pit at depth 8 feet No caving. No seepage. ~---------------------------------ii } § Ironwood King County, WA ~ Logged by: JDC Associated Earth Sciences, Inc. Project No. KE0 31738 ~ Approved by: IBI I f;\I liJ Iii! M April 2003 !;! _______________________________________ _ 1 - 2 - 3 - LOG OF EXPLORATION PIT NO. EP-17 This Jog Is part of the report prepared by Associated Earth Sciences, Inc. (AESI) for the named project and should be read together with that report for complete interpretation. This summary applies only to the location of this trench al the time of excavation. Subsurface conditions may change at this location with the passage of time. The data presented are a simplfication of actual conditions encountered. DESCRIPTION r\Sod and Topsoil FIii Loose, wet, olive-gray, dark brown, and dark gray, nonstratified, silty, fine to coarse SAND, few fine to coarse, subrounded to subangular gravel, few scattered concrete rubble and boulders to 30" in diameter, few organics. (SM) r 4 +---------------,Ac:d;:-v:::a-=n-=-c-=-e·o""u"'tw=as:.hc---------~------ Dense to very dense, wet, weakly stratified, fine to coarse SAND, little fine to coarse, subrounded to rounded gravel, few silt. (SP-SM) 5 - 6 - 7 - 8 - 9 - 11 - 12 - 13 - 14 - 15 - 16 - 17 - 18 - 19 - Bottom of exploratlon pit al depth 1 O feet Minor caving in the upper 5'. Heavy (5 gpm) seepage below 4'. ~---.,-----------------------------1'! I & Ironwood King County, WA ~ Associated Earth Sciences, Inc. J N KE03173B ~ Logged by: JDC Pro ect o. jj Approved by: II I f}:I ~ Iii! • April 2003 ~----------------------- LOG OF EXPLORATION PIT NO. EP-18 g . This log Is part of the report Jrepared by Associated Earth Sciences, Inc. (AESI) for the named nroject and should be ,; read together with that repo for comnlete interpretation. This summary a~plles only to the loca Ion of lhis trench at the C. time of excavation. Subsurface condi Ions may change at this location wit the passage of time. The data presented are • Cl a slmplflcatlon of actual conditions encountered. DESCRIPTION Sod and Topsoil 1 -Fill Loose, wet, olive-gray, dark brown, and dark gray, nonstratlfied, silty, fine to coarse SAND, few fine 2 -to coarse, subrounded to subangular gravel, few scattered concrete rubble and boulders to 30" in "\diameter, few organics. (SM) r 3 -Weathered Till Dense to very dense, moist, light olive-brown, nonstratified, fine to coarse SAND, little silt, few fine 4 - to coarse, subrounded gravel, trace roots, trace subrounded cobbles. (SP-SM) 5 TIii 6 -Very dense, moist, light olive-gray, fine to coarse SAND, little silt, few fine to coarse, subrounded gravel, trace subrounded cobbles. (SP-SM} 7 - 8 -Advance Outwash Very dense, moist, light olive-gray, gravelly, fine to·coarse SAND, trace silt. (SW} 9 - 10 11 - Bottom of exploration pit al depth 10 feet No caving. No seepage. 12 - 13 - 14 - 15 - 16 - 17 - 18 - 19 · ~---------------------------11° l ~ ~ ii ~ Logged by: JDC Approved by: Ironwood King County, WA Associated Earth Sciences, Inc. Project No. KE03173B Aprll 2003 ---------------------------------- 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 - 11 - 12 - 13 - 14 - 15 - 16 - 17 - 18 - 19 - LOG OF EXPLORATION PIT NO. EP-19 This log is part of the report prepared by Associated Earth Sciences, Inc. (AESI) for the nSmed project and should be read togettier with that report for complete Interpretation. This summary applies only to the location of this trench at the time of excavation. Subsurface conditions may change at this location with the passage of time. The data presented are a simplflcation of actual conditions encountered. DESCRIPTION Sod and Topsoil Advance Outwash Dense to very dense, moist, weakly stratified, fine to coarse SAND, little fine to coarse, subrounded to rounded gravel, few silt. (SP) Bottom of exploration pit at depth 1 0 feet No caving. No seepage. ~-w-----------------------o1--------------...;., ___________________________ _ I ~ ~ Ironwood King County, WA ~ Associated Earth Sciences, Inc. ~ Logged by: JDC Project No. KED3173B jj Approved by IMI I ~I [Iii a till April 2003 ~----------------------- 1 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 - 10 11 - 12 - 13 - 14 - 15 - 16 - 17 - 18 - 19 - LOG OF EXPLORATION PIT NO. EP-20 This log is part of the report prepared by Associated Earth Sciences, Inc. (AESI) for the named project and should be read together with that report for complete Interpretation. This summary appltes only to the location of this trench at the time of excavation. Subsurface conditions may change at this location with the passage of time. The data presented are a simplficatlon of aclual conditions encountered. . DESCRIPTION Sod and Topsoil Advance Outwash Dense to very dense, wet, weakly stratified, fine to coarse SAND, little fine to coarse, subrounded to rounded gravel, few silt. (SP-SM) Bollom of exploration pit at depth 10 feet Moderate caving. Heavy seepage below -5'. ij-z!:l---------------------- l'l° J ~ Ironwood King County, WA ~ Associated Earth Sciences, Inc. Project No. KE03173B ~ Logged by: JDC ~ Approved by !Bl I '.fi'.\ ~ iii m April 2003 ~------------------------------ 1 LOG OF EXPLORATION PIT NO. EP-21 This log is part of the report prepared by Associated Earth Sciences, Inc. (AESI) for the named project and should be read together with that report for complete Interpretation. This summary applies only to the localion of this trench at the time of excavation. Subsurface conditions may change at this location with the passage of time. The data presented are a simplfication of actual conditions encountered. DESCRIPTION Sod and Topsoil Weathered TIii Medium dense, moist to wet, light olive-brown, nonstratified, silty, fine to coarse SAND, few fine to 2 -coarse, subrounded gravel, few organics as roots. (SM) 3 - 4 - 5 Transition to Advance Outwash Very dense, moist, light olive-gray, fine to coarse SAND, little silt, few fine to coarse, subrounded 6 -gravel, trace subrounded cobbles. (SP-SM) 7 - 8 9 - 10 - 11 - 12 - 13 - 14 - 15 - 16 - 17 - 18 - 19 - Bottom of exploration pit at depth a feet No caving. No seepage. ij __________________________ _ ii J ~ Ironwood King County, WA ~ Associated Earth Sciences, Inc. ~ Logged by: JDC l"-~J I ·.i'ii:.,· .. , ~ .. ,... Ce'.1J ~.-.· · .. ·... Project No. KE03173B ~ Approved by: -L" ~ IIBI ~ April 2003 ~--------------------------------------------- 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 - 11 - 12 13 14 - 15 - 16 - 17 - 18 - 19 - LOG OF EXPLORATION PIT NO. EP-22 This log ls part of the report prepared by Associated Earth Sciences, Inc. (AESI) for the named project and should be read togettier with that report for complete Interpretation. This summary applies only to the location of this trench at the time of excavation. Subsurface conditions may change al this locatlon with the pass'\ge of lime. The data presented are a simplfication of actual conditions encountered. DESCRIPTION Sod and Topsoil Advance Outwash Dense to very dense, moist, light-olive brown, weakly stratified, sandy, fine to coarse, subrounded GRAVEL, grades to light olive-gray, fine to coarse SAND, few subrounded to rounded gravel, trace silt. (SW/SW) Bottom of exploration pit at depth 1 o feet No caving. No seepage. ij--26--------------------------.., ____________________________________________ _ I Pi Ironwood King County, WA ~ Associated Earth Sciences, Inc. I'! Logged by: JDC Project No. KE03173B ~ -Approved by 1111 ! 'fit! Iii! aJ 1111 April 2003 ~--------------------------------------------- Associated Earth Sciences, Inc. Exnloration Loa ~ ~ ~ ~ ffl Project Number 1 Exploration Number I Sheet . . KE04766B EB-1 1 of 1 Project Name BQ§!llilQDl-Ea~t B1an\Qn i:[QQ!ll:t~ Ground Surface Elevation (fl) -4:iQ !!let Location !Sing QQua!)( WA Datum ~,, ... Driller/Equipment Date Start/Finish lOMlOZ lOMlOZ Hammer Weight/Drop l~Qlf I 30" Hole Diameter (in) g • u-~ !~ ii! ! :c.8 Blows/Foot ~ §_ lH. ~~ s ~ s:~ " ~ " • 0 • T c., (I) ~iii • a (/) 0 6 DESCRIPTION " 10 20 30 40 -Forest Duff and Toesoll r Colluvlum Moist, dark brown, silty SAND, with organics, gravel, and wood . . S-1 Weathered Vashon Lod\ement TIii 2 A 2 \ Moist to very moist, mottled gray and yellow-rown, silty fine SAND,~ 5 -5 gravel. ___ Vashon Lodgement TIii 13 S-2 Moist, gray, silty fine to medium SAND, wilh gravel, few cobbles. 30 74 " -10 Advance Outwash S-3 13 Moist, brown, fine to medium SANO, trace silt and gravel, unstratified 20 A43 23 ,_ 15 Moist, brown, fine SAND gradin~ to fine to medium SAND, trace silt, S-4 14 A33 unstratified with slightly more sil at 16.5 feet. 18 15 ~ 20 "' S-5 Wet, brown and yellow mottled, lamlnated, SILT, with fine sand, liltJe gravel 7 .. ., grading to saturated fine SAND, with silt, little fine gravel, weak 22 --.. stratification. .. -23 Bottom of exploraUon boring at 21 5 feet Ground water at 20 feet L 25 L 30 L. 35 ~ "' i ~ ~ i Sampler Type (Sn: 1! [Il 2" OD Split Spoon Sampler (SPT) 0 No Recovery M -Moisture Logged by: SGB ~ [Il 3" OD Split Spoon Sampler (D & M) II] Ring Semple 'SJ. Water Level () Approved by: m I\,] 0 Shelby Tube Sample-'l a; Grab Sample Water Level at time of drilling (ATD) ~ Associated Earth Sciences, Inc. Exploration Lon ~ [13 iiJ 1'il ffi Project Number I Exploration Number l Sheet . KE04766B EB-2 1 of 1 Project Name Bgsemcat-East Beatca ecc12ect)i Ground Surface Elevation (ft) -435 feet Location ~iog Q12uat~ '11.8 · Datum • ••A Driller/Equipment Date StarVFinish 1 Ol4lOZ, 1 Ol4LOZ Hammer WeighVOrop 140#/30" Hole Diameter (in) g C l~ j • u-_.g ·-0 .3 ~ ! ~.a Blows/Foot £ ~[ ~i ~ s E ~ ~ ~ • T • """ 2 0 0 U) 0 ~co £ DESCRIPTION u 20 0 10 30 40 -' . Grass and To~soll r Recasslonal Outwash S-1 Very moist, brown, fine to medium SAND, with silt to silty fine to medium • ... SAND, little gravel and organics. 2 • ~ 5 Very moist, brown, SILT, with fine sand, little gravel. S-2 4 .. ,, • 6 ~ 10 S-3 Advance Outwash 4 Wet, gray-brown, SILT, with fine sand, lillle gravel 10 11>30 --·-~-------20 Bottom of oxploratlon boring al 11.5 foot Saturated but no free ground water on drill rods or in hole ~ 15 ~ 20 ' ~ 25 I-30 ~ 35 ~ ,; ~ J ;;: G ~ Sampler Type (ST): ~ [!] 2' OD Split Spoon Sampler (SPT) D No Recovery M -Moisture Logged by: SGB ~ rn 3' OD Split Spoon Sampler (D & M) ill Ring Sample 'fl. Water Level () Approved by: 0 e ~ l!'J Shelby Tube Sample.V. Waler Level at time of dnlllng (ATD) 0 Grab Sample ~ Associated Earth Sciences, Inc. Exoloration Lon @I) LE] ~~ m Project Number I Exploration Number Sheet ·:·' KE04766B EB-3 1 of 1 . Project Name BQS!!aJQOH;ast Beo\QO P[QQ!!i:l~ Ground Surface Elevation (ft) -165 !~~! Location !Siog QQuot~ Wt, Datum ~,,A Driller/Equipment Date Start/Finish j Ol~lOZ j OMlO:Z Hammer Weight/Drop HO#/JQ" Hole Diameter (in) € C .; . -l,l • .!,! i5 =i ~ !!2 j! .c .0 Blows/Foot ~ a 0. o. E ..., . ~--3 s E E,, ,: e $ .2 ~ ~ T • (!) (/) " <J) 0 ~ 0) £ DESCRIPTION <) 10 20 0 30 40 "\ Grass and Toesoll r Weathered Vashon Lodgement TIii S·1 Moist, gray-brown, silty fine to medium SAND, with gravel. 3 "12 3 • -5 S-2 Moist, gray-brown, silty fine to medium SAND, little gravel. 10 .. ,, 11 12 L-10 S-3 Vashon Lodgement TIii 25 Moist, gray, silty fine to medium SAND, with gravel and cobbles 22 ' " 17 ~ 15 .. S-4 Advance Outwash 22 Gray, SILT, with sand and gravel grading to medium SAND, with silt and 14 .. 2 gravel, no stratification. 11 L. 20 Moist, brown, fine to medium SANO, with coarse sand, gravel, few sill, no S-5 11 stratification. 14 "" 16 ' 25 Moist to vei moist, brown, fine to medium SAND, trace silt, little oxidation S·6 13 .. , at 26 to 26. feet, non to very weakly stratified. 16 16 L 30 Saturated, brown, stratified, fine to medium SAND, with silt and gravel. S-7 15 A42 20 22 11'. L. 35 ij S-8 Saturated, brown, weakly stratified, medium SAND, trace silt, tittle gravel. 9 "'" 16 " -~ 23 ! Bollom of elCplorallon boring al 36.5 feel I H ground waler likely 30 feet ~ i Sampler Type (ST): [Il 2" OD Split Spoon Sampler (SPT) 0 No Recoveiy M -Moisture Logged by: SGB ~ rn 3" OD Spill Spoon Sampler (D & M) DJ Ring Sample 'ii. Water Level () Approved by: 0 l!I !iii lZI Shelby Tube Sample .i. Water Level at time of drilling (ATD) ~ Grab Sample ~ Associated Earth Sciences, Inc. Proctor Analysis ASTM D1557, D698 Date Sampled Project Project No. Soll Description 16-Aug-07 Rosemont East Renton KE040766B Tested Bi Collected By Location EB/EP No. I Depth Sand w/ grave, few sill MS till EP-1 3'-4' !Percent passinQ 3/4" sieve-94% ASTM D 1557 Method C Automatic Tamper A Mold Number 1 2 3 Remarks B Water Added field wet dry C Wt. of Wet Soll+ 22.445 22.480 22.570 Mold lib\ D Wt. of Mold (lb) 12.405 12.405 12.955 E Wt. of Wet Soil (lb) 10.040 10.075 9.615 F Wet Density, (pct) 133.867 134.333 128.200 G Wt. of Pan (lb) 0.495 0.485 0.485 H Wt. of Wet Soil+ 2.390 2.615 2.935 Pan 'lb\ J Wt. of Dry Soil + 2.195 2.345 2.720 Pan llb\ K Wt. of Water (lb) 0.195 0.270 0.215 M Wt. of Dry Soil (lb) 1.700 1.860 2.235 N Moisture Content 11.5 14.5 9.6 %\ 0 Dry Density (pcf) 120.1 117.3 116.9 z For a 6 Inch mold: Z = 0.075 For a 4" mold: Z = 0.0333 140.0 Test Results: 135.0 Optimum Moisture Percentage: 12.5 130.0 Maximum Drv Densitv: 121.0 - f 125.0 Correction for oversize: ASTM D4716 51120.0 .~ "" Corrected Moisture Percentage: 11.8 '1:J 115.0 Corrected Maximum Drv Densitv: 123.1 i:' ,, 110.0 .105.0 Assumed Specific Gravity: 2.7 100.0 0.0 5.0 10.0 15.0 20.0 25.0 moisture content, % ASSOCIATED EARTH SCIENCES, INC. 911 Fifth Ave., Sulle 100 Kirkland, WA 98033 425-827-7701 FAX 425-827-5424 Associated. Earth Sciences, Inc. Proctor Analysis ASTM D1557 1 D698 Date Sampled Project Project No. Soll Description 16-Aua-07 Rosemont East Renton KE040766B Tested Bi Collected By Location EB/EP No. I Depth 1 SIity Sand w/ gravel MS Brown SM EP-2 G'-4' l ,S' ,< Percent oassina 3/4" sieve: 89% ASTM D1557 Method C Automatic Tamper A Mold Number 1 2 3 Remarks B Water Added field wet wet C Wt. of Wet Soil+ 21.670 22.630 22.620 Mold lib' D WI. of Mold (lb) 12.405 12.955 12.405 E Wt. of Wet Soil (lb) 9.265 9.675 10.215 F Wet Density, (pcf) 123.533 129.000 136.200 G Wt. of Pan (lb) 0.490 0.500 0.495 H Wt. of Wet Soil + 2.515 2.605 2.410 Pan 'lb' J Wt. of Dry Soil + 2.310 2.375 2.150 •, Pan lib\ K WI. of Water (lb) 0.205 0.230 0.260 M Wt. of Dry Soil (lb) 1.820 1.875 1.655 N Moisture Content 11.3 12.3 15.7 ''%\ 0 Dry Density (pcf) 111.0 114.9 117.7 z For a 6 inch mold: Z = 0.075 For a 4" mold: Z = 0.0333 140.0 Test Results: 135.0 Optimum Moisture Percentage: 14.5 130.0 Maximum DN Densitv: 118.0 i 125.0 Correcllon for oversize: ASTM D4 718 ii &: 120.0 Corrected Moisture Percentage: 12.9 , . .., -115.0 Corrected Maximum Drv Densltv: 122.0 i!' ,r .., 110.0 105.0 Assumed Specific Gravity: 2.7 100.0 0.0 5.0 10.0 15.0 20.0 25.0 moisture content,% ASSOCIATED EARTH SCIENCES, INC. 811 Flnh Ave., Suite 100 Kirkland, WA 88033 425-a27,7701 FAX 425-827-5424 Associated Earth Sciences, Inc. Proctor Analysis ASTM D1557, D698 Date Sampled Project Project No. Soll Description 4-0ct-07 East Renton/Rosemonte Pro KE040766B Tested B: Collected By Location EB/EP No. I Depth Brown Silty Sand. trace gravel KME EB-3 Upper till I Percent passing 3/4" sieve-100% ASTM 01557 Method C Automatic Tamper A Mold Number 1 2 3 Remarks B Water Added field dry dry C Wt. of Wet Soil + 23.205 23.040 22.190 Mold /lb\ D WI. of Mold (lb) 12.760 12.180 12.180 E Wt. of Wet Soil (lb) 10.445 10.860 10.010 F Wet Density, (pcf) 139.267 144.800 133.467 G Wt. of Pan (lb) 0.500 0.500 0.500 H Wt. of Wet Soil + 2.055 2.035 2 430 Pan /lb\ J Wt. of Dry Soil + 1.880 1.920 2.310 Pan /lb\ K Wt. of Water (lb) 0.175 0.115 0.120 M Wt. of Dry Soil (lb) 1.380 1.420 1.810 N Moisture Content 12.7 8.1 6.6 '%) 0 Dry Density (pcf) 123.6 134.0 125.2 z For a 6 inch mold: Z: 0.075 For a 4" mold: Z: 0.0333 140.0 Test Results: -Optimum Moisture Percentage: 9.5 135.0 ---------- 130.0 ------"\. ·-· -·-Maximum Orv Densitv: 137.0 -·-\ f 125.0 0 Correction for oversize: ASTM 04718 ~ jj 120.0 Corrected Moisture Percentage: 9.5 ,8 .9: 115.0 r;, Corrected Maximum Orv Densitv: 137.0 " 110.0 -- 105.0 ---·-------Assumed Specific Gravity: 2.7 100.0 0.0 5.0 10.0 15.0 20.0 25.0 moisture content,% ASSOCIATED EARTH SCIENCES, INC. 911 Fifth A.ve., Suite 100 Kirkland, WA {16033 425-827-7701 FAX 425-827-5424 Associated • ..I Date Sampled 10/4/2007 Tested By Austin Sample ID Wet Weight+ Pan Dry Weight+ Pan Weight of Pan Weight of Moisture Dry Weight of Soil % Moisture Sample ID Wet Weight+ Pan Dry Weight+ Pan 'ght of Pan ;Jht of Moisture Dry Weight of Soll % Moisture Sample ID Wet Weight + Pan Dry Weight+ Pan Weight of Pan Weight of Moisture Dry Weight of Soll % Moisture Sample ID Wet Weight+ Pan Dry Weight+ Pan Weight of Pan Weight of Moisture Dry Weight of Soll % Moisture ) Earth Sciences, Inc. Project Project No. East Renton/Rosemonte Proi KE0407668 Location EB/EP No. EB-1 2.5' 510.9 415.9 101.8 95.0 314.1 30.3 EB-115' 331.1 309.6 101.9 21.5 207.7 10.4 EB-2 5' 303.8 275.2 95.2 28.7 180.0 15.9 EB-3 5' 273.0 267.9 94.0 5.1 173.9 2.9 I Depth EB-1 5' 408.5 367.3 101.0 41.2 266.3 15.5 EB-1 20' 380.1 339.1 94.1 41.0 245.0 16.7 EB-2 10' 430.9 404.8 93.·t 26.1 3117 8.4 EB-3 10' 375.4 366.6 93.5 8.8 273.1 3.2 Moisture Content ASTM D 2216 Soll Description ASSOC/A TED EARTH SCIENCES, INC. 911 51h Ave .• Suite 100 Kirkland, WA 98033 425-827-7701 FAX 420·827-5424 EB-11 O' 347.1 326.3 98.6 20.8 227.7 9.1 EB-2 2.5' 252.7 241.5 91.1 11.2 150.4 7.5 EB-3 2.5' 209.7 203.2 97.4 6.5 105.8 6.2 EB-315' 414.1 411.7 94.1 2.4 317.6 0.8 Associated 1 J Date Sampled 10/4/2007 Tested By Austin Sample ID Wet Weight+ Pan Dry Weight + Pan Weight of Pan Weight of Moisture Dry Weight of Soll % Moisture Sample ID Wet Weight+ Pan Dry Weight + Pan •·· •1ght of Pan Jht of Moisture Dry Weight of Soil % Moisture Earth Sciences, Inc. Project Project No. East Renton/Rosemonte Proi KE040766B Location EB/EP No. EB-3 20' 297.4 295.7 91.7 1.7 204.0 0.8 EB-3 35' 602.4 557 6 214.4 44.8 343.2 13.1 I Depth EB-3 25' 375.0 364.1 93.2 10.9 270.9 4.0 Moisture Content ASTM D 2216 Soil Description ASSOC/A TED EARTH SCIENCES, INC. 911 5th Ave., Sult& 100 Kfrtland, WA 96033 425-627-7701 FAX 425·827-5424 EB-3 30' 490.0 451.4 94.5 38.6 356.9 10.8 Associated Date Sampled 8/17/2007 Tested By MS Sample ID Wet Weight + Pan Dry Weight + Pan Weight of Pan Weight of Moisture Dry Weight of Soll % Moisture Sample ID Wet Weight+ Pan Dry Weight + Pan iht of Pan Jht of Moisture Dry Weight of Soil %Moisture Sample ID Wet Weight + Pan Dry Weight + Pan Weight of Pan Weight of Moisture Dry Weight of Soll % Moisture Sample ID Wet Weight + Pan Dry Weight + Pan Weight of Pan Weight of Moisture Dry Weight of Soll % Moisture Earth Sciences, Inc. Project Project No. RosemonUEast Renton KE040766B Location EB/EP No. Exoloration Pits EP-1 thru 12 EP-3 6' 1.925 1.820 0.745 0.105 1.075 9.767 EP-4 14' 2.805 2.100 0.690 0.705 1.410 50.000 EP-4 4' 2.920 2.840 0.875 0.080 1.965 4.071 EP-2 6' 2.495 2.385 1.125 0.110 1.260 8.730 'Depth EP-4 6' 2.200 2.160 0.865 0.040 1.295 3.089 EP-4 10' 3.335 3.020 0.690 0.315 2.330 13.519 EP-3 4' 1.235 1.185 0.655 0.050 0.530 9.434 EP-3 2' 1.945 1.875 1.125 0.070 0.750 9.333 Moisture Content ASTM D 2216 Soil Description ASSOC/A TED EARTH SCIENCES, INC. 911 5th Ave., Suite 100 Klrkland, WA 88033 425--827-7701 FAX 425-827-6424 EP-5 6' 1.600 1.530 0.735 0.070 0.795 8.805 EP-6 4' 1.695 1.600 0.695 0.095 0.905 10.497 EP-5 2' 2.165 2.065 1.150 0.100 0.915 10.929 EP-2 3' 2.440 2.245 0.655 0.195 1.590 12.264 Associated Date Sampled 8/17/2007 Tested By MS Sample ID Wet Weight+ Pan Dry Weight + Pan Weight of Pan Weight of Moisture Dry Weight of Soll % Moisture Sample ID Wet Weight+ Pan Dry Weight+ Pan ·1ht of Pan ,iht of Moisture Dry Weight of Soll % Moisture Sample ID Wet Weight+ Pan Dry Weight + Pan Weight of Pan Weight of Moisture Dry Weight of Soll % Moisture Sample ID Wet Weight + Pan Dry Weight + Pan Weight of Pan Weight of Moisture Dry Weight of Soll % Moisture Earth Sciences, Inc. Project · Project No. Rosemont/East Renton KE040766B Location EB/EP No. Exoloratlon Pits EP-1 thru 12 EP-10 3" 1.290 1.225 0.660 0.065 0.565 11.504 EP-7 4' 1.750 1.705 1.150 0.045 0.555 8.108 EP-5 4' 1.185 1.135 0.655 0.050 0.480 10.417 EP-6 12' 4.265 3.710 1.145 0.555 2.565 21.637 I Depth EP-9 3' 1.735 1.630 0.650 0.105 0.980 10.714 EP-6 6' 1.960 1.760 0.725 0.200 1.035 19.324 EP-6 2' 1.545 1.465 0.655 0.080 0.810 9.877 EP-6 15' 3.905 3.425 0.870 0.480 2.555 18.787 Moisture Content ASTM D 2216 Soll Description ASSOCIATED EARTH SCIENCES, INC. 911 5th Ave., Suite 100 Kirkland, WA 98033 425-827-7701 FAX 425-827-5424 EP-9 2' 1.665 1.600 1.150 0.065 0.450 14.444 EP-8 5' 3.605 3.405 0.735 0.200 2.670 7.491 EP-6 9' 3.245 2.940 1.015 0.305 1.925 15.844 EP-8 3' 1.655 1.610 0.905 0.045 0.705 6.383 Associated Date Sampled 8/17/2007 Tested By MS Sample ID Wet Weight+ Pan Dry Weight + Pan Weight of Pan Weight of Moisture Dry Weight of Soll 'lo Moisture Sample ID Wet Weight+ Pan Dry Weight+ Pan 1ht of Pan Jht of Moisture Dry Weight of Soll 'lo Moisture Sample ID Wet Weight + Pan Dry Weight + Pan Weight of Pan Weight of Moisture Dry Weight of Soll 'lo Moisture Sample ID Wet Weight+ Pan Dry Weight+ Pan Weight of Pan Weight of Moisture Dry Weight of Soll 'lo Moisture Earth Sciences, Inc. Project Project No. Rosemont/East Renton KE040766B Location EB/EP No. Exnloration Pits EP-1 thru 12 EP-7 7' 1.885 1.835 1.105 0.050 0.730 6.849 EP-4 O' 0.000 0.000 0.000 0.000 0.000 #DIV/OI EP-7 O' 0.000 0.000 0.000 0.000 0.000 #DIV/OJ EP-10 O' 0.000 0.000 0.000 0.000 0.000 #DIV/01 I Depth EP-10 2' 1.385 1.270 0.740 0.115 0.530 21.698 EP-5 O' 0.000 0.000 0.000 0.000 0.000 #DIV/01 EP-8 O' 0.000 0.000 0.000 0.000 0.000 #DIV/OJ EP-11 O' 0.000 0.000 0.000 0.000 0.000 #DIV/01 Moisture Content ASTM D 2216 Soll Description ASSOC/A TED EARTH SCIENCES, INC. 911 Slh Ave., Suite 100 Kirkland, WA 98033 425-827-7701 FAX425-827-6424 EP-3 O' 0.000 0.000 0.000 0.000 0.000 #DIV/01 EP-6 O' 0.000 0.000 0.000 0.000 0.000 #DIV/OJ EP-9 O' 0.000 0.000 0.000 0.000 0.000 #DIV/OJ EP-12 O' 0.000 0.000 0.000 0.000 0.000 #DIV/01 Date 10/4/2007 Sieve No. 3.5 3 2.5 2 1.5 1 3/4 3/8 #4 #8 #10 #20 #40 #60 #100 #200 100 BO " • C 60 u: ,! '·U 40 .~ o,· 20 0 100 "" 3• GRAIN SIZE ANALYSIS · MECHANICAL er Till 2236 2080.B 490 1590.B 1476 55 Project No. KE040766B EB/EP No Depth Soil Description Moisture% 9.8 Soeclficalion Reaulrements Diam. /mml Wt. Retained 1n1 % Retained % Passinn Minimum Maximum 90 0 0.0 100.0 76.1 0 0.0 100.0 64 0 0.0 100.0 50.6 0 0.0 100.0 38.1 0 0.0 100.0 25.4 0 0.0 100.0 19 33.5 2.1 97.9 9.51 97.1 6.1 93.9 4.76 192.7 12.1 87.9 2.38 257.9 16.2 83.8 2 276 17.3 62.7 0.85 347.9 21.9 78.1 0.42 456.6 26.7 71.3 0.25 673.2 42.3 57.7 0.149 855.2 53.8 46.2 0.074 954.8 60.0 40.0 US STANDARD SIEVE NOS. 3/4" N04 NO 15 N040 NO 200 ,0 0.1 0.01 Grain Size, mm ASSOC/A TED EARTH SCIENCES, INC. 911 5lh Ave., Suite 100 Kirkland, WA 96033 425-827-7701 FAX 425-827-5424 Date 8/17/2007 Tested By MS Sieve No. 3.5 3 2.5 2 1.5 1 314 318 #4 #8 #10 #20 #40 #60 #100 #200 100 80 -" C 60 3" u: 'E 11; " ~ " 0. 40 -ti 20 0 100 " GRAIN SIZE ANALYSIS -MECHANICAL Project Rosemont Location East Renton 1808.56 1668.56 311.69 1356.87 1464 53 Project No. KE040766B EB/EP No EP-1 Depth 3.4• Soil Description Moisture % 10.3 Snecification Reauirements Diam. lmml WI. Retained % Retained % Passino Minimum Maximum 90 0 0.0 100.0 76.1 0 0.0 100.0 64 0 0.0 100.0 50.8 0 0.0 100.0 38.1 0 0.0 100.0 25.4 96.42 7.1 92.9 19 113.17 8.3 91.7 9.51 265.22 19.5 80.5 4.76 414.53 30.6 69.4 2.38 515.4 38.0 62.0 2 533.1 39.3 60.7 0.85 621.5 45.8 54.2 0.42 756.4 55.7 44.3 0.25 917.5 67.6 32.4 0.149 1049.0 77.3 22.7 0.074 1139.9 84.0 16.0 US STANDARD SIEVE NOS. 3/4" N04 N0.16 N0.40 N0.200 : - 1--i-1---- ~ ~ -+-~11-1~ ~ -~--t-~- --: -i-!= -1-- -\- H--1--1 - - -~-----1-- , -!-Cl--l--!--+--l-!ll--1--1---i-"I-S'-l--'1-1-- 10 0.1 0.01 Grain Size, mm ASSOCIATED EARTH SCIENCES, INC. g 11 5th Ave, Suite 100 Kirkland, WA 96033 425--827•7701 FAX425-327-6424 Date 8/17/2007 Tested By MS Sieve No. 3.5 3 2.5 2 1.5 1 3/4 3/8 #4 #8 #10 #20 #40 #60 #100 #200 100 BO " ~ 60 .. 1: ~ 40 • .. 20 0 100 3• GRAIN SIZE ANALYSIS · MECHANICAL 1720.89 1619.65 311.89 1307.76 1370 8 Project No. KE040766B EB/EP No EP-2 Depth 0-3' Soil Description Moisture % 7. 7 Sneclflcation Reauirements Diam. Imm' Wt. Retained 1n1 % Retained % PassJnn Minimum Maximum 90 0 0.0 100.0 78.1 0 0.0 100.0 64 0 0.0 100.0 50.8 0 0.0 100.0 38.1 0 0.0 100.0 25.4 0 0.0 100.0 19 139.09 10.8 89.4 9.51 281.8 21.5 78.5 4.76 396.63 30.3 69.7 2.38 493.0 37.7 62.3 2 508.9 38.9 61.1 0.85 579.3 44.3 55.7 0.42 677.0 51.8 48.2 0.25 816.0 62.4 37.6 0.149 944.2 72.2 27.8 0.074 1046.3 80.0 20.0 US STANDARD SIEVE NOS. 3/4" N0.4 N0.16 N0.40 N0.200 ' ~ y-- ---;- I• •: ,, --11-- ;---1! ~ i~ --~ - 10 0.1 0.01 Grain Size, mm ASSOC/A TED EARTH SCIENCES, INC. 911 5th Ave, Suite 100 Klrkland, WA 98033 426-827-7701 FAX 425-827-5424 APPENDIXB JP>avemell1lt Sectioilll Recommendations for 148th A veilllue §]E Associated Earth Sciences, Inc. ~ ~ Jli.IT:"l ~ [;(al ~ .~~:~, ~ ~ ~ ee,6rafing Over 231fears of Service August 19, 2004 Project No. KE01508G CamWest Development, Inc. 9720 NE !20th Place, Suite 100 Kirkland, Washington 98034 Attention: Ms. Sara Slatten Subject: Subsurface Investigation, Supplementary Geotechnical and Pavement Section Recommendations for 1481h A venue SE Street Improvements Shamrock Nursery Project King County, Washington Dear Ms. Slatten: This letter presents pavement section design and construction recommendations for planned improvements along the west shoulder of 148th Avenue SE fronting the subject property. Specifically, we understand King County requires a site-specific pavement design for improvements to extend to the fog line of the southbound lane of 148th Avenue SE. The County has classified 1481h Avenue SE as a Collector Arterial. This letter represents a continuation of our work on the project, which has included completion of subsurface explorations, laboratory testing, preparation of several geotechnical engineering reports and letters, and ongoing construction monitoring for the project. This study was completed in response to an e-mail from Ms. Slatten received on August 3, 2004. We were subsequently authorized to proceed by means of a CamWest purchase order. This work has been completed in accordance with local geotechnical engineering standards of practice at the time it was completed. No other warranty, express or implied, is made. Subsurface Investigation and Conditions We performed a limited subsurface investigation on August 6, 2004, consisting of three exploration pits at the locations shown on Figure I, attached. The exploration pits were completed to expose the native subgrade along the proposed improvement area. A Dutch Cone Penetrometer was used to classify the density of the subgrade within all three explorations based on published correlation charts with Standard Penetration Resistance (N) Values. As shown in the exploration pit logs, attached, we encountered from 6 inches to 3.5 feet of structural fill overlying a native weathered till subgrade. The subgrade ranged in density from Kirkland 425-827-7701 a Everett a· Tacoma 425-259-0522 253-722-2992 www.aesgeo.com I~ loose to medium dense. The overlying structural fill appeared to have been compacted to a medium dense to dense condition, although no in-situ density tests were performed on the fill. A composite sample of both the native material and of the structural fill was collected and delivered to Mayes Testing Engineers for California Bearing Ratio (ASTM:D 1883) with Moisture Density Relationship . (ASTM: D 1557), and Mechanical Grain Size Analysis (ASTM:D 2487-98) testing. Testing results are included with the calculations at the end of this report. These tests were used to arrive at design parameters used in our analysis. Pavement Section Recommendations We have completed an analysis of the pavement section for the planned southbound lane of 148"' Avenue SE fronting the project site. The analysis was completed using data provided to us, laboratory testing data, assumed traffic data, data presented in Section 4.03 of the King County design standards, and American Association of State Highway and Transportation Officials (AASHTO) design methods (1993). Copies of our calculations are attached with this letter. Traffic inputs were based in part on information provided by Transportation Engineering Northwest, LLC including year 2003 ADT (average daily trip) values for two directional traffic on 148"' Avenue SE, south of May Valley Road. No breakdown of vehicle classes was available. The "East Renton Traffic Study" by Garry Struthers Associates, Inc. documents the average growth rate in the area as 2.57 percent. In order to calculate an ESAL (18 kip Equivalent Single Axle Load) value for use in the design, we were forced to make assumptions regarding the class distribution of heavy and light vehicles. We used the City of Auburn Pavement Design Manual as a guide to formulate our assumptions regarding the heavy vehicle distribution. The heavy vehicle distribution assumptions and the calculated ESAL are shown in the calculations. Based on our analysis, we recommend a minimum pavement section consisting of 4 inches of asphalt concrete paving (ACP), underlain by 6.5 inches of crushed rock base (CRB). Alternatively, a paving section using asphalt treated base (ATB) could consist of 2.5 inches ACP, above 3.5 inches of ATB, above 4 inches of CRB. These thicknesses should be considered compacted thicknesses. The pavement section must be placed over a minimum of 22.5 inches of existing structural fill or an equivalent amount of new structural fill compacted to 95 percent of ASTM:D 1557. The fill must be placed on properly prepared native soils compacted to 95 percent of the modified Proctor maximum dry density. Alternatively, unweathered, undisturbed dense till soils can be used below the CRB to replace some or all of the 22.5 inches of structural fill. Paving materials and procedures should be consistent with current Washington State Department of Transportation (WSDOT) design standards. We understand that King County will require the new southbound lane paving section to be equal' to or better than the existing paving section on 148"' A venue SE, regardless of the results of our analysis. Therefore, we recommend that the existing paving section be measured at the time of construction. If the existing paving section is more substantial (with a higher 2 Structural Number) than paving recommended in this letter, the new paving section should be revised to match the existing paving. Shoulder Areas Where paving will be widened to form new turn lanes, we recommend that existing shoulder areas be excavated to expose suitable underlying native soils, and that the planned paving subgrade be restored with structural fill placed in accordance with the recommendations contained in our earlier final geotechnical engineering report for the project. The existing shoulder areas should not be used to support paving. Fill material placed to raise grade below paving should consist of native materials, or imported materials that will provide pavement support characteristics similar to native soils. We should be allowed to offer situation-specific recommendations if materials other than native or on-site soils will be used as structural fill beneath paving areas. CLOSURE We have enjoyed working with you on this study and are confident that these recommendations will aid in the successful completion of your project. If you should have any questions, or require further assistance, please do not hesitate to call. ) Sincerely, I ASSOCIATED EARTH SCIENCES, INC. Kirkland, Washington . ~a/IA .»-p'c!Zl~Jt.,w---' Sfaan G. Beckham, P.E. Project Geotechnical Engineer Attachments: Figure 1: Site and Exploration Plan Kurt D. Merriman, P.E. Principal Engineer Copy of Exploration Pit Logs EP-1 through EP-3 Pavement Design Calculations Laboratory Test Results SOB/Id· KP.OISOBGIO · Projects\2001508,KE\WP · W2K 3 ~~ f ( "'7\ \ ' "' ,:i' ··-I / ~~ } --- ~ j___;_ LJ "0 --" crrYr:r...,.itN --" LEGEND EP-1 D Approximate location of exploration pit N A ~ m. i /~ .. ~ct1Ji. i 4:::±::±-: I J) I _y'-'--\'lk=cc~--~·1.1 D i ,,-,:::::::::=jl 11 :.--,--~ • =:,:-~-:_ 11 1 ~==;:::=::;::;::;';:::;;:~;::'r=~ ••;:':':::::: '=f--===~=============;~m~~ll~":i;;;'~n~~~~:,=============:R=EF=ffi:E=N=~=•:T:RIAD=::A=~:~~~:~:S:.I:~~· j Associated Earth Sciences, Inc. SITE AND EXPLORATION PLAN FIGURE , i m ii ~ ~ la 148THAVE~~~~~~~~VcMENTS .;: KING COUNTY, WASHINGTON PROJECT NO. KE01SOBG OATE M>4 ) .i (J) 0 ~ ~ C 0 J 0 -~ Well-graded gravel and GW gravel wilh sand, little to no fines ';~;,;;;i--+:c--c---,---,----- Poorly-graded gravel and gravel with sand, little to no fines Silty gravel and silty GM gravel with" sand Clayey gravel and GC clayey gravel with sand Well-graded sand and SW sand wilh gravel, little to no fines Poorly-graded sand and sand with gravel, lillle to no fines Silly sand and SM silty sand with gravel Clayey sand and clayey sand with gravel r--+----------1 Sill, sandy sill, gravelly silt, ML slit with sand or gravel Clay of low to medium plasticity; silty, sandy, or gravelly clay, lean clay Organic clay or silt of low plasticity Terms Describing Relative Density and Consistency Coarse- Grained Soils Fine- Grained Soils Density SPT 121 blows/foot Very Loose O Lo 4 Loose 4 to 10 Medium Dense 10 to 30 Dense Very Dense Consistency Very SoN SoN Medium Stitt Stitt Very Stiff Hard 30 to 50 >50 S PT 121blows/foot 0102 2 to 4 4108 8 to 15 151030 >30 Test Symbols G = Grain Size M = Moislure Content A = Atterberg Limits C = Chemical DD = Dry Density K = Permeability Descriptive Term Boulders Component Definitions Size Range and Sieve Number Larger than 12" Cobbles Gravel Coarse Gravel Fine Gravel Sand Coarse Sand Medium Sand Fine Sand Silt and Clay 3" lo 12" 3• 10 No. 4 {4.75 mm) 3" lo 314• 3/4" lo No. 4 (4.75 mm) No. 4 (4. 75 mm) lo No. 200 (0075 mm) No. 4 {4.75 mm) to No. 10 (2.00 mm) No 1 O (2.00 mm) to No. 40 (0.425 mm) No 40 (0.425 mm) lo No. 200 (0 075 mm) Smaller than No. 200 (0.075 mm) C3 ) Estimated Percentage Moisture Content Dry -Absence of moisture, dusly, dry to the touch Slighlly Moisl -Perceptible moisture Percentage by Component Weight Trace Few Little With <5 5 to 10 15 to 25 • Non-primary coarse constituents: ~ 15% · Fines conlenl bet-Neen 5% and 15% Moist · Damp but no visible water Very Moist -Waler visible but not free draining Wet -Visible free water, usualty from below water table Symbols Blows/6" or portion of 6" Sampler Type Elastic silt, c ayey s It, sill 2_0,,00 MH with micaceous or Split-Spoon I • " • Sampler Type Description Cement groul surface seal \ Bentoni!e ,, seal diatomaceous fine sand or Sampler --1-"si"-lt _______ -1 (SPT) Clay of high plasticity, CH sandy or gravelly clay, fat clay with sand or gravel Bulk sample 3.0" OD Split-Spoon Sampler 3.25" OD Split-Spoon Ring Sampler •• Filter peck with :: blank casing ::-section ·•• Screened casing :.· or Hydrollp --+-----------, Grab Sample 3.0" OD Thin-Wall Tube Sampler (including Shelby tube) ·: with fitter pack •. Endcap o Portion not recovered Organic clay or silt of OH medium to high plasticity (ll Percentage by dry weight (2) {SPT) Standard Penetration Test a--+-------~ (ASTM 0-1586) Peat. muck and other (3) In General Accocdance with PT highly organic soils Standard Practice for Descriplion and Identification of Soils (ASTM D-2488) t4l Depth of ground water ~ ATD = Al time of drilling Jl_ StaUc water level (date) t5l Combined USCS symbols used ror fines between 5% and 15% Class!ncatlons of &Oils In this report are based on visual field end/or laboratory observations, which Include denslly/eonslslency, moisture condition, grain size, end plastlclty estimates and should not be construed to Imply field or laboratory tesUng unless presented herein. Vfsual-manuel and/or laboratory classlflcaUon ; meUiods of ASTM D-2487 and 0-2468 were used as an Identification guide for the Unined SoU Classrncatlon System. Associated Earth Sciences, Inc. ~~~~[Q] I ----------------------------------- FIGURE A-11 LOG OF EXPLORATION PIT NO. EP-1 g This log Is part of the report rrepared by Associated Earth Sciences, Inc. (AESI) for the named ftroject and should be £ read together with that repor for comRlete Interpretation. This summary iplies only to the loca ion of thls trench at the a. time of excavaUon. Subsurface condl ions may change at this location wi the passage of time. The data presented are • Q a slmplfication of actual conditions encountered. DESCRIPTION Toosoll . 5/8" minus crushed rock road base. 1 Tvne 17 oit run structural fill. - Weathered Till 2 -Medium dense, slightly moist, brown, SIL TY SAND with gravel, trace organics. Standard Penetration Resistance INl Value' of weathered till = 18. 'N-Vaiue based on correlation charts 3 -u1sed with Dutch cone oenetrometer. 4 -Bottom of exploratron pit at depth 2 feet No ground water or caving. 5 - 6 - 7 - 8 - 9 - 10 - 11 - 12 - 13 - 14 - 15 - 16 - 17 - 18 - 19 - Shamrock Nursery -148th Avenue SE i Renton, WA 2 ,_ - . ~ Associated Earth Sciences, Inc. Project No. KE01508G ~ Logged by: SGB m ~ ~ ~.. ~ Approved by: ~ ~ ~ ~ ~ August 2004 ~------------------------ ) LOG OF EXPLORATION PIT NO. EP-2 Thls Jog is part of the report prepared by Associated Earth Sciences, Inc. (AESI) for the named project and should be read together with that report for complete Interpretation. This summary applles only to the location of this trench at the time of excavation. Subsurface conditions may change at this location with the passage of time. The data presented are a slmplficallon of actual condltlons encountered. DESCRIPTION r\ccT.=Oc.PS=.cOc,cilc__~-~~-~-----------------------~r t\5/8" minus crushed rock road base. r 1 -Structural FIii 2 - Medium dense to dense, moist, brown, SIL TY SAND with gravel. 3 - Weathered TIii 4 -[\Loose to medium dense slinhtlv moist brown. SIL TY SAND with nravel. N-Value =10. 5 - 6 - 7 - 8 - 9 - 10 - 11 - 12 - 13 - 14 - 15 - 16 - 17 - 18 - 19 - Bottom of exploration pit at depth 4 feet No ground water or caving. r ~---2 1' -Shamrock Nursery • 148th Avenue SE J ! Renton, WA ~ Associated Earth Sciences, Inc. Project No. KE0150BG !! Logged by: SGS ~ ~ ~ ~ fi:SI i __ A-pp_,o_v_•d_b_Y' _________ ~ ___ m;;i ___ t'OO_· _LE_'' __ ~_. _________ A_u_g_u_s_t 2_0_0_4_ LOG OF EXPLORATION PIT NO. EP-3 g This log Is part of the report J,repared by Associated Earth Sciences, Inc. (AESI) for the named Rroject and should be . 5 read together with that repo for comnlete lnterpretalion. This summary a~plles only to the loca Jon of this trench al the C. lime of excavation. Subsurface condl ions may change al this location wit the passage of time. The data presented are 8 a slrnplficatlon of actual conditions encountered. DESCRIPTION 1Tonsoil r -5/8" minus crushed rock road base. -1 -Structural FIii 2 Medium dense to dense, moist, brown, SIL TY SAND with gravel. 3 Weathered TIii Medium dense slinhtlv moist, brown SIL TY SAND with nravel. N-Value = 16. 4 -Bottom of exploration pit at depth 3.5 feet No ground water or caving. 5 - 6 - 7 - 8 - J 9 - 10 - 11 - 12 - 13 - 14 - 15 .. 16 - 17 - 18 - 19 · ~---------------------------~ I Shamrock Nursery • 148th Avenue SE Renton, WA § i Associated Earth Sciences, Inc. Project No. KEo 1508G ~ Logged by: SGB ~ ~ l"fflilil ~ ~ ~~~Ap_p_rov_•_db_y_'~~~~~~~~-~~~~~~-~~~L:Jlt~·~lf:,t!ll-·~~~~~~~~~A-u-gu_s_t_20_~~ Associated Earth Sciences, Inc. JobFlle D Phone Log D Calculation ·~:, Memo D 9 I I Fifth Avenue, Suite I 00 Kirkland.WA 98033 DISTRIBUTION: 425 827-7701 FAX 425 827,5424 Incoming Call O Outgoing Call D FIie 0 Conference 0 Info D Date -~o,_/.c-'1?'-+-'!o~V~---r I Project No. Project ~J~li_=M"l~,,t-"'!J-"C-"-'/c__~. -------~-- Subject_~~/) _______________ _ Person/Company ----------------- Phone No. ---------Page __L of 7_ I '6 Lf 0 2-v.JO_'( ...... r (;_ .. ! -"-:z..02-3 3fS-,-b '! :,7'i) ( 5,)) ~dJcJ$+·e+-;,, 2.... <:·-) ,:/...J...F'°'JJ.;:,:{-,~,c-.. 0_. ~-·J"c...£·f-1 '-· ,:-_,;\.J.?;::.. 2....,. 'l /.5(,,,;h/·?.-.~1:::i-{c.) 51'/z..:;:. 2 · f./ ). ( .-)''?.!'°(. i.··::.? ,~()/( Or.J '·. ' , .·.·.c, /'/! -:: .. I. 7S (C.-'-'-'-·'-"'·,.':.1:,-) ··n ,.·i'c "'' ·· · '-·~·· . '/; ···'•, .. -, .) ) 5oL-V[.. Foll f»./.1 e.11. '-'/{,_t.£,,,f_.,f,JJ..-4..-D C15;1tcce/f £=-o, If 'I ~ a1 ,4 ,8 ~ !) ' 30 ;:. Cl.z_. owaltRJ t;n,,oc.,c.(.-7,J L 0, I '-I -;;: Ot :, 1'1 Clh c ( bo r f't?"/,v ;;; O , I I ::c <'1 'i /J,1 111 , h1 u""' / a.-y e,, c//?ru-l::...ru'?..<J4. /" -,.-,-i 1) L 4 . · II 'j".Y'/ c I .c>j/P'di .. , '!:" "'° 4,, .5°' a.79 , tBa-te -:. 11 -'/ (,e,!f f, 1,~ ,4/.SHlc! ' VI ct.t. I 9 7 3) ( oe/6' (111 ,_:'-M,,,) -· 0, ff (.r;,;,_ lvj;>2S), -<Mi:,_,r,::/1,-, •• ) (Ta.-£../J..t 2-1 t../ ,4 ,"J.-;H.7.:~ i??.s') Reviewed By------ Associated Earth Sciences, Inc. JobFile 0 Calculallon J2:f7 911 Fifth Avenue.Suite 100 Kirkland, WA 98033 DISTRIBUTION: 425 827-7701 FAX 425 827-5424 Incoming Call D Outgoing Call D FIie 0 / , 7 &. ~ . G ·1-2... -· 2, L/ 3 Phone Log O Memo 0 Conference 0 lnlo 0 Date f /; [1 /o I/ I , Project ""2 (A f/#'(Y(J'(/c .. SubJect_-J_.JL ________________ _ Person/Company ----------------- Phone No. ---------Pege '2-of 2_ /, 7 .f, (/'.52. ?.-.._\· ,,. C.rv:5;:.,_.:!,/ /CCJt:!c.. ·--------·-------·------· 5f'J 3 -(SN,"'+-S/J,_") ;• "/ /YI 3 X 7 ·· ./. IS 2, 7 -( 2, 'i&' -/, 7(:,) 1.' 0 '/ •, //} (?) . .-j l'"' . D ~ • J.. ( ·• _I L; II .. rfif ,,_-ri,. ?··· -=---------..... </ _,.-· ,._. _/ . /' ) /~ < ....... ···--· ",>/r ., -Ip·' ) (.' F~-'"'; / ..,,,ji ' / /,J(:,, <;) /, I ~-(, 3)(D2:-) (,1#f.) ~ r-/ = 2. 7 ~ 2,7 ? i) -) 2--,, (0 Signature -~.;#,i'..P,.s<"'<... 2'.'lLL'------Reviewed By _____ _ \"._ '~'cl ''\\ '"--....,_ ~ total ADT* = percent of traffic truck composition 0.98 passenger cars 0.0028 bosses 336895 0.0114 pickups (8,000# gross) 0.0028 2 axle, 6 tire (12,000# gross) 0.0009 Concrete trucks 0.0011 Dump trucks 0.0002 10-wheel trucks (46,000# gross) 0.0002 10-wheel trucks (80,000# gross) 0.0002 5-axle, dual trailer (82,000# gross) 2% heavy vehicles, distribution not available ADI equivalency factor EAL US-kip, daily) 330157 0.0006 198.09 943.306 11.52 10866.89 3840.6 0.0203 77.96 943.306 0.1203 113.48 303.206 4 1212.82 370.585 1.89 700.40 67.379 2.12 142.84 67.379 2.45 165.08 67.379 4.12 m..fill. 1.00 TOTAL EAL tB-kl• 13755.17 Note: Traffic breakdown per "Pavement Thickness Design Manual", October 18, 1990, by City of Auburn, Department of Public Works: Rural/Local Residential Roads & Residential Collector Arterial Roads, p.5. *Projected Growth Rate per year (i) for design life 20 2.57% Projected Growth: (TOTAL EAL)[(l+i)0 -1/i]=G 353858 0.35 EAL for design in millions * Traffic data provided by Curtis Chin, P.E. of Transportation Engineering Northwest, ILC (\ .. l CIVIL ENGINEERING REFERENCE MANUAL Appendix B: Revised Soil Support Correlations "-90 L 90 L L 10 "-80 '-80 '- '- -9 --,u -- 'o• { ' ' '-l! '-60 '-60 [._ - '- '-7 50 '-50 .. '2 '-'-0 ·e L So C 0 ~ '-40 '-6--~ ~ '-40 ~ a: m mL fl '- , , ..,. '- ..,. > > a: a: L 30 '-6 '-30 L '-L L 20 L... 4 20 '- '-'-'-10 LM L3 L ,_ '-0 L2 I-0 C. Ll ,-.,_'>··- ':: 100 -90 .:: BO 1-70 I- 1-60 L... 50 r-f t.,L-- 40 M1 (1,.·! '- -- .... '-20 L Lo _ 10 t::: 9 '-8 .... '-7 I-5 I- I-a -'-s X '-m ,, '-4 .E L-10 C. , e L3 "' '-L 15 L2 L L 20 Ll ... - 'ii .s a: :. e a , ... a: 0 .... w , :i .... 'O 0 :. .... L .... .... - 40,000 30,000 20,000 10,000 9000 8000 7000 6000 5000 4000 3000 2000 "- ~ \, \,, ' ~ !!.. a: i5 :.; .5? .; a: [ om1 ] loglO[ 4.2 -1.5 J log1f 18 = Za"S0+ 9.36*l09i0 CSN+1l -0.20 + + 2.32*log1o"a -8.07 1094 ~Slllll£S, 0.40 +--5 19 (SNtl) • l ]l "":; ~ Design Serviceability Loss. APSI -: c.!. , -.. . ~~ .J 10: ·5 -~ /"' = j -40 o..: o-~ :;; 0 U) ~ -' .!! " ::; ~20 !!1: ~ .c .; v ~~ i: " ~ . 0 -6 = "" .5· ~ C, ~o~ V V, '! ~ ::; / :· .. ~ 'E t-. -· I/ v/. o-g~ L.. .,, .!l .:! :::= ' .: .!! Wm IP. Lf , , ~ ,,., "' V / .!: U) loo' / 10, l,,/ 1/j,i r,t Elomple: ,.,, ~ 2.0 ' ' ' ' . ' ' . ' • W10 = !5 • JO 0.35 ...... ,l(,r." • •-:2 • .., 2 9 8 7 I 5 o.v•, Oesion Structural Number, SN :: s ~R • 95 % ~s0 , o.35 -*Mo• 5000psl .,,~ l O, [JC{) p s1 (1h_ .f.,v! cv..,J .5!-,..vc.f., . ..,,.,J: '·' ,; 5'.lbh?' . .t,c. _) $ r~,r./(., r. -l"APSI • 1.9 ! ' 5' Solution, SN • 5.0 ~ • 7 Figure 3.1. Design Chart for Flexible Pavements Based on Using Mean Values for Each Input -¥:-I( 1 V\(., (n /-)( ;,cv1-~ :J ?-ci.t-r\.lv• r.\A () __ ;:1 '\ V' r I:}, \/ ,:, ... V.1,...,z_-6 '1 --( ) ~ l- ,Q, ? i a 5'> ~ I /',. \~ "' '.'.'. "" s;\-_ ·, ;e !a- "' ~ :a 2 • er ~ SOD7ES: log11f1a = ZR*So+ 9.36*logl0(SN+1) r A PSI 1 loglO[ 4.2 -1.5] -0.20 + + 2.J2*109ich -8.07 1094 0.40 +--5 19 (SN+l) • lj_ ]l Design Serviceability Loss, 6PS1 -~ -40 dP( oc_ ,:ffl "' .!f C .c .,; i-2 ='o 0 ~ ~ ~j~ I/ ,I Z' -~ ,:; ~ . / '/,.1, 1W ~~ ~ w"' ..!!:! -· , , {1 V , 115/ /, ~ u/ ~ ~ ,~. 2.0 w. ' ' ' ' . . W10 = s x 10' --=-, 3S-1: o {, 9 8 7 fi S • • 2-<fS 2 R=95o/0 ..,. 'f,':·\ Desion Structural Number, SN $0 ' 0.35 C O . , MR * 5000 psi :::. JqD-.:, D C-;-,'a ,..,-( /,,,t:" r 1-1':., ' 6PS1 , 1.9 , • . < Solution, SN ' 5.0 " .2.. '"f 5 Figure 3.1. Design Chart for Flexible Pavements Based on Using Mean Values for Each Input - ,; :::: ~ f. ~ ;:p ~ ~ ~ ~ ~ ~ ~ i's_ ~ ~ " "'-- i=,,m swm;, r • PSI 1 10910[ 4.2 -1.5] log1 ~\8 = Za"S0 + 9.36*109i0 (SN+ll -0.20 + + 2.32•1og1 o"a -s.01 1094 . .,. r,f> ~8;ff -~,! a: 0 • l>-~ .g = § :a ;;; ~ 90 : 80 70 go "° \. "° ,o .00 1~ c! ~ !! > ,; -... IU C Q..g ~j .,-il -~! i-;-·'·" !~ in~ "' C .; 0.40 + (SN+l)S.19 Examplo: " =a~ "' . -0 ::; m • .c 0 -o a i::i a: "8 m::; :E:: C: ~~ w m a: W -5 x 10 6 · ;..;,:y /'' t~ IG --' --r...,- R.::i95°/o ,tr;· i. S 0 : 0.35 C (), (,_... MR: 5000 psi , :Jg, Q(''.~~/ ~PSI : 1.9 " , . < Solution: SN ;. 5.0 Design Serviceability Loss, APSI Air ~ /v / ~ w , , , , I'/. / '/ ,,./ /1 ~ ,.,I /I, ~ 1."'.'. 2.0 ~ .. ' ' ' 9 8 1 6 5 • 3 • Oesl9n Structural Number, SN {(Y·,1 1 , /.; S• :...•, fr:.c.,:.. • ,, ) Flgure 3.1. Design Chart for Flexible Pavements Based on Using Mean Values for Each Input . ,, ~ .,. ~ f. .,a, ;p ~ ~ I ~ ~ "1i ,, -· :· ""(!(1 ... 1 :•:, · MAYES TEST! HG EHG lt·IEERS MAYES TESTING IEMGINIEIEIRS, Di\fC. l;\tA·#IME i : '.\Tl·.· ;~, 181 ~1)0.-1 '------- ( L [El':T: A~sociatt!d Earth Sciences .. Inc. Pi·!1).i l·1·.· T: K.EO l50f:G -----· :-:•)JH, I" ,1: _Q-10.18 I Ii '' W/.10 REPORT STATUS; Original 0 Amended 0 SAMPLE DESCRIPTION: 425 7'-15 17.37 Evemll Off/,:;o 917-134th Street ~W Sul1e A·1 Everett, WA 98204 ph 425,742.9360 fax 425.745.1737 1scoms Offlce 10029 S. T8COfTlfl Way Suite E-2 Tacoma. WA 98499 ph 253.584.3720 fax 253.504.3707 Portland Qtflcs 7911 NE 33rd Drive Suit~ 190 Portland, OR 97211 ph 503.261.7515 lax 503.281.7579 Brown Silt w/gravel (Native Shamr~c::k:L) ____________ _ TEST RESULTS: California Bearing Ratio ( ASTM DI 883) .. .... ~~.implc. ft 8740 Brown Silt w/gravel ,vl;,;~irnnni Dry I >cnsity (lb/cu.ft.) 129.3 (ip1in\l.~~-~J.:i.(~!~~!~~c';:.:1t:.en::r:..":..fo:._ ______________ _.._:8:.:·:.8 _________________ _ ••• '.1~::orl111)t":--.ur,:]u1r_t~'.' __ lb--s _______________ _;;1,-'o ... oc_ _____________ _ . __ ·\1 :.;\'.'ell ill ivl.ix Dr.v :..:L>.ce;.:11.;;.s;.:ity"---------------O:..:._l.:_'X:..:•--------------- ;;,i~ .,_i:r•,1:Jxi111u1n Di:: l icnsity .1" · 1c'.1; :n inn (>u<1bxl f 82.0 ·--·-----·-·---··· -------------------------------- ... --··-'"·-····--------------- Reviewed By:ea__.6Q~~;2.'.',L'.....~===---. J;,1,.111,~ti;iu 1n 1hi, r1:p,:,r1 ,1pplic:. only to the iii;\ual samples t,rncd and shall nol beteproduccd cxccpl in full~ lnc. illl ,· CJ .;:i 0 ~ ::, "' ~ ~ ti' " C ;.";! -· ,,, _, 0 ~IAYES TEST!HC, EflG!flEERS CBRValue ~ 425 7£15 1737 "' 0 iTt~ re--~TTTl1"'Tr -,-i -:-srl-, T"T-C1rr+-r-.-rr-t--rr-,--;--t--,--,-.,..~. I . 1 ! 1 · ! r++: ++1-+1-+1-ll+P--. H-H-+++ .... --·-1 .l --1-I : ·+-H-+-+-+-+-t-+-Hrl-+-1-+-+-+-+-+--H-· • i I~· ' i I I I -H--H-++t-H-+-c++-H ,.. 1_, I ·-'H--iic-HH-ii-H++++++-+-+l++-1~· I ---, .:..L ..l\ . i 1-1--t! ..,1-+-++-tl--t-++--t-t+-H--t-ri! ... l .. --,-,....,..-,--,-, ~ ~1-i ·H·-t.-1:-++t+H+H--H+tt++ --·1--t-++-+-t -· ... ·: ! i ,1--f-. .1.H,_1-+++-+-t++-H-+++-t--t-+t-+-f+-! -I J -'-,-+ .............. -+-+-1-,1--. ·ri-+-++-t+-H-+-t--crt-+-+-+-r-H _, TH : ·t·+-~+++-+-YIH-1-+-++++-+-c-H-+-++ -·i--1--t---I--I--H ~; -, l I . -/ I --·1-++-lrr-t-1-+-+-+--t-rr+-1-+-+-+-+-t++-I--H I L.(. -·-f 1,--J I i i ·-t-1-+-+-+-tl-H-+-++-:-;:-+-i----··t-i--i--i--H -:---i_--;__-t-i---tt--t;-_,1:_;_-i -+·+-l-+-+-+4+-+--+--i-H-t---· -··ri--t-t-i---1--t+i--t--t-+-t-t- · f-r-i I I I I -· -l, l-H-,-,....,-,....i-,-i---i .. I I I I \: I i i i ~-+-;-++-r+l'--l-+-+-:--+-t--'-1-··;-' ·,· 1' \ ! ! . i i 1 I . • ---· · J • \ • --/-j--j-lc-'--,--j--t--j--i,-j ' i ' : I I H--~ ! I I I ' I ' I • I i : I I . I i i !-l.·1 I '.I I L' i i i ! : : i i I i I j 1· 1 . I ; I +--+ -.L.L_, __ L --I -: : 1·--__ , __ ;_.I,-+-;-' --t--,-+-H,t--;-,-;-t+-;-;-'ri '1-c'--t--t' -i ,::~ 1 .._LL· I I i 1 , 1 1 · _; 1' 1· , i J L-·H·+:~+-'' +' +ir++i...,'-+-i ~! +-H ;.J ' j I ! .l l ~ : I I : : ! L ! I __ J. ·I -1 ! I - I 1--I -" c, ,. ' ,. ., >J o, ; i : I : .r 1\--J--r-I 1 J -!--i-·;r'. +-t-+-t--t-tl--t-1 t-1 -tl-+-'-++-t+-H -' · , ' U-J.~---! I 1-1 1 r:'I--Mr-:'--HH 1 .-4~~+.i , , 1 :\l r , 1 : • , 1 ·-· }l: ,_ ! ,-cr_tt,-~,1\-+I ~/ _s-,~1,=:._:1 :::.: ~, ~=::::::~:;~;+;-,-.,.-+- , ... L~c+-· 11 '-f-' : . , , I ! I ' I I . : ! H-' ' i . ·-·I-"\-' +' +-H-+-+-IH-+-t-+-+-++-1-++-tf- l l ; : , .i: : + I\ ,1-i--t--t-_-r_ -+_--t. --HI--I--H-+-t--Hrrt-+++-i 1--· ~J_i_J_. u! ~ i i : ,, I u ' . i ' " ,, i i i I I f--+-H-+-+++-t-+-+++-t-+-+-+-H l"j +-t' I I-,! I I Ji : : ·1• ~·H-, -H!'++.l.-+i+H_'<f.,~+H+H-1 +-t+H--j I 1 • ! 0 I I ! I ! I I I '·--,-I ,. 1--t'-t--l-;>+-:-, +-t-+-H-++, ++--t·"'rrl . . . ! . ··I··-++I -t-t--t--t,--Hc-1 -~. -!--i i !. ' I 11' : ' I !-, ---i....;+ I I i I " ' ' I I ' ' '! ' ' -1--t-+-t-+-t-++-t--t-t-7+-t .. J I i.f--~H-: ' ' j I I -I LU ' ! i ' I : ! i I ' I ' ' ' ' I I ' ' ' --·- I : H-' ' .. ' j i ! I '·+-1-l ! ! I I .. ! I i ·,- I I i -· -i i ' -- i I I '. · : : OT 1 ] /-·+Tr-1H-+ !. +-t.c+• 1 ~,-'11-, 1 -+- 1 +-t-f-:1 + ;: +-t 1 H-+1~1-1 . ----' -I . h--f-i;-,..-,-,-,-.,-r . f ! I / ··i·-1\l·H---t-t--t---t-,-,..-H &1 -J.J I , , , , , r t,..·+-1 'i-+-+-·.,. 11 -+-t++-t1-+-.,.., i--t--t-Mrr-t --1 i I : , I ·1 , ' , ... -1.t-+-t-+-t--t-+-e,; .. t-t: '.l1.t-__+·I' -i,r-t-: -i--,,1 ~ '" ,, "' "' · :1~1 : I > ,-· , rj+,-,-,-,--f-j ++ __ +~:.:....~~-;_-;_-;_-;..-;...:j-•T"TT 11-j---H r+-+-r+-+-1-+i +++I +++++-r-t-~ .... ' I I l[~ ! ! i .. _L./ ... i I : ' I I I --' . I I I ; -·'· I : ' ; I I : I i~:; i k-i i . r- I i .. I 1f :1, I ' !·-·· .. I · ·1·, , , , I ~ ,H--:·J ·1 i . ~-J-.L. ' I i ' i I I I i l I I ! i i ! H · ·,-'+-,, +-1-t-+' +-IH--t-,-t-+: -+i-i +-t-+-1-++-1-+-1-++-+--t+I H--I I MAYES TEST lt·IG E,IG 1,IEERS .::!25 7,:15 1737 Moisture Density Relationship Test As::;oi;1akJ fauih Sciences Inc. Date 8/18/2004 c·ii,.:m !11y,je1:I Tiu ~'kthc,rl 1)u a I ity <~.o:':'ntrc=-ol;.,....,..-,-::,-,-:-:=~ =,..,-,,-,.,,,-,-,,,e- A ST M 1'.155i. Method Cl ASTJv! C: 127 / D4716 (if needed) Project Number Lab Number 04029 (KEOI508 Qi_ 8740 " d :•.·;:11;1r.1hon [ l Hai1d Tamper r,,.,, Prcp:;rn1ioP [JL·~ Mechanical t\vc fi.c'.i:O.':ivcd R,•J:2004 ·.::.:..:c,--~--,.-,1;r(<: ,_11·:)::11upic.> ~-lh!Lvt Shamrock f 1,_:~,cril-'1 i-. )f! ol S;irnµle: ~ ~1wn r.ilt with gravel : /vri"> \'iiid !jnr. plnr1r:d .it SpG 2.75 ! [\1:i:<. T)ensiry Ur.rmrret'.tcd 129.0 -., :·.-'.\ 1! 1 I- -I I! i ' 1: ' I :1 • ·1•: '' I i·I· 11 " l· -! J •.. ,. Ir -· I .I. .. i" -· · II I 8.8 129.3 Sieve Si2e Percent Retained ·I· -I i I " ' .. :j ! 11-' , . : :ii+t --l ! I· j ·I I I J. · ' , , ,-;-! I 1· I· ' ' I , --~ , +· .1. ' ·-· H i: -I t -. 1-H- 3/4 18 3/8 32 #4 44 H ! 1 : -: ; : .. I I---+ ' -! I I I:. . I ' 1-· -: : ; I I t 1-++1 I -' i ·I- " •1 1-·.' . i I ·;--i .,.., . '. . -!--LI '' ' _, i i·j-' i- 1-, f· .. j.' rr-ii-:r.~ '; I· l-:-1 :.i + +' ' -'-1 ! /--4--,-, .. ' " ·-·1:-ffi .. . •' --:-. I ; .. ' --,-,-·· -1 ' I I •-- ' ' ' ' I . ' -r·l··r-. rt . ~li :11 :+: ! ' i --. .:...+-t -.., .. : ! t +I -·Hi i -:·!·i + + ) l I 0.0 :~.n 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0 Water Content. % of dry Weight ~-·----··-···-···------------• '1"(4'1';. !n/<11u1;1tio11 in 11li} Iep,Jri ~pnlies only Lo !he ectuat samples tested and shall not be reproduced except i Enginecs, htc. MAYES TESTING ENGINEERS 'We Make a Difference" --< 0 --< p. v :3 ·1111 ,=~ I ______ .,--.. ,--.,~.,._ .. ,·,·-------~-_________ ·:,-.. ·r-:,-~ .. :-h·c:·.r·:.,~;-.:.:~:-:r..1-.. !;,, "" ~ .~. :~r_ l 1·~ I: .J-r-:-,. ~ .. ,.. • ·-· : ; -· ·-i: I ..... r· I .1---, , , " , ' j· ' 'j. , I . ! -. j -_, _ -. '"'·Pfl: r1----i·:_1::..,~.:.·1· , ___ -,, ,.-.: .l:-1--, ! I '.. : f -:_-::, 1 :·--: ~--~ i --!-i --'.·· ' I ! _!__: --•---- " 1-_, -, ' TI , -,--1--, ---1 i----~-13-~~J-:- : ~::-:: : •=!ta~= _c:::~ Jr-~ '~ C ' ;c ~' --, -• .. :~ . I-~~ ~: . -=--=-! ---·! j "~ -· ·= -=:;=~nt=m~-------=---::-~ ----.----_____ -_-:-·-·:_ -= , "'1-1= ·---~'·· . __ :.::: "' ·i---1·-' ·l-1-+--·t-·--I---·i- "' -+--t-1="=t.:.+ 1-k --- ------ \I~ I---+-+-- -1---+ . t=+=J=+l+l=l-=R=EEf--E-···--i=f--=t---t=F--~~ &=§~£.... - •••1 : Sk·vr Am~!vsis , -=.;.c..;__ ___ s-_-, ____. ... Sr.:·,•;; .:::1,,: I ~-;. ?1.-;sink_~ ).:);;·· '.:; ... -·-'" 2.Jo•· t-u~-... 314"' 5/8'"' Ill" 3/8" J/4'' 114 #8 #iO •16 #30 1/40 #50 #100 1/200 lllO 9~: 97 '" " n 87 SJ 80 15 69 62 57 49 47 42 35 30 26 18 12.4 H..-::. 10,000 :5M Sr:,:: 1 .. , mm. m.;;.."t j :~~ ~ Ul --< m ul --< 7 Cl cp E'i ffi m Ji too to ,., O.UL Cr.ala Siu (mm) • C~riis i>f &:oi:,.,c~r1 lfllifcn111Sall CL:uslfinti1111 ,th (ft CIDssification NuL W.C. IL.L. P.I. 8740 ;:; .. ~.c ·.;:G0:.\.1 Matena): Brov.'Tl Salld}'. silt with ~,..cl Source: Nath.·e Shamrock Project: ualit Control Pro·ect ff: Q4029 (ICE01508 G) Date Rec'd: ~ ~ Revicwt:O by: / /.1....,..?, _,;:r ..?'--,... MAYES 7tSTING ENGJNEiERS ·...-~, ,...,,,;. .. ~ S'iii•1•<f"<:'"'"• L "' Vl -J L 'Jl --J Ld -J .,, C, .,:, ' ·7-• :' ii,· MAYES TEST I HG Ef!G I flEERS MAYE$ TOTING ENGINIEIERS, BMC. l>,\'l'I'. 8/18/2004 ...c___:..:;,._;:_:_;c.:.._ ______ _ :"'I ll :~.Jr: As:,rn:iJkd Earth SclencesJ Inc. nro:FC'I': KFOJ5();)G ·---------------- !'l!O!E• T # (>402fi ------------ ; /.l~ /~ :{/ll ! --------··------- REPORT STATUS: Original 0 Amended 0 SAMPLE DESCRIPTION: 425 7~5 1'737 Everett ON/cs 917•1.l41h Street SV/ Su~e A-1 Everen, WA 90204 ph 425.742.9360 fax 425.745.1737 Ta~tima Office 10029 S. Tacoma W<.iy S1,1rte E-2 Tacoma, WA 98499 ph 253.584.3720 fax 253.584.3707 Ptittla'1d Office 7911 NE 33rd Drive Suite 190 Pi:irlland, OR 97211 ph 503.261 .7515 lru,: 503281.7579 Gray Sand w/grovel (Shamrock Fill) --------· -----. -----="'"'-==--"'-'=c.:::->e===-=.:c2---------- -------· ·-·------------------------------------ TEST RESULTS: California Bearing Ratio ( ASTM D 1883 ) ________________ _;:c_;:,;:_,;.:.;.:;.cc.::_:.=:==-'-"==.:.:.:c::..,_ _________ _ _ __;:S ___ a.c_m,pk Ii 8727 [1c~•crip1ion Gray Sand w/gravel H:,:<~1~1<n !)1)' Drnc:s.::ity,_,(l.::bc./c.:.u:.:·.:.ft:o.)c_ __________ l:.:3:::6c..4;_ ______________ _ '. __ lpl 1n1t1111 tvloi::lln e C,_1J_:1l::e:.:nt:.0.::Y":._ ____________ _;7c..9:._ ____________ _ ·-···--\·Veiglir 01 Su1char:,,r,e_' _Ih_•---------------'-10.;_._0 _______________ _ ____ .2.:i_·sdi nt Ma . ..: Dty D.:nsity 0.1% J 1.R ·1\ /VIm:it1:l m l)1y !.,ensity .1 11 r·.;:ni:-_, 1 :1 ii ·~·:1 __ ~ :, ~'.~~~-~·:!). . . -----------------·------- 64.0 ··---.. --------------------------------------- Reviewed By: _. -".:::::~:::;~;,::!:::..--- h, k 1w:1u, ,11 m ll\13 r,~p,:,rt o.pph·;~ 1 mly to 1hc '"rual snmplcs tcslcd :ind shnll not be reproduced cx,;cpt~, Inc. t "P,l,' R.~t;IJl!t; :~·74 l /'.i/ ! .~/2004 ?: :··") C, "- ['-,,, ['- ~ C) " ['- KJ " U) O' w w z ~ w ~ f- LO w f- U) w >- (I ,: California Bearing Ratio (ASTM D1883) Soaked Sample. Laboratory #8741 70 I I f-f-~ 111 : I I l±±t111 ~j I~ i ltSf~ffl 1111111~w::t:=di±t±t • .::{~:,j~ Z=='=-- 65 ~ 1111 I~ ti , I~ j 1 , , 1 ---.... : , ·H--: I.I-: ; .. +_'._ __ · __ I ___ : ... ,-J __ J__ . --,,i/ / : I : I ' --.... ---~ I I : I I ' · / . ' ' ' --J--j=t1--' . j . ' ' -t : VI I : I I I r ' . -+--i-t-!---1-------i : -1_---r--r:::: 1 I y' 60 '" ::, iii > 55 0:: m f.) ;.... I I/ EfH I 111E~~1--+~=tf1tl=f-tr=l~1;1-Hffl 1+H+n1-· · T- 50 I I -, .. :. 1-.~_..:·-J---LJ ____ , __ -_r--- r. -!--~--; -r---· J=t±· tti4+-+ ... l.~:~ 45 r=-, I I I i 1 : -+----f:-. -= _:_ _ -:--r --= -~rj_J -~' -,----i I :··: ~-I ·; ! -·-I : -, ; I ·1l ' 1-----~--~-·-·-··-···· __ • 1 • __ i _ J !, . . ---------···. , 1 : ,-t·-,,· -----.11. +---..... I_ 1 · f ' I I I . ·-' ... , -~-' ' . . -,----i--.... o . : ' ! ; -' I ·-·--·; i ·---~t .! l :___ : . : . 1 1 i ! ; . I I L_J -i : -,---r---I -I i ·-1 126 -,29 1.:.~1 1 ~~-!32 133 1;:4 12-S :35 137 !Jry Density (lb/cu.ft.) :'.t;,.-s:: ·-·~ :~::.:··,,~2. ·~;- n ;c,-, ~r--_, Qi ~, 100 r- r'1 c::; ,. ' If) 1--" ['-••!= If) o, " ' 70 "' ! so ~ ' ~ t-.. ,_ l ! Ul I ,.. Cl'. w ~ ,. CJ 1--1-1-z w ~ .. ~--tL ---f-- .. r:,. --+-- r---- 5ien Ama.lJsb Siu Qflcning IU bldin H~ of Mesh per !rich. US Sbadant .. .. "' •• M . " .. .. .. ~ ·~ ,~ i-------=I= ·--+--·-- ------- -f=f--E t---~ ·---:-· _--··-· .----------·-r---r--· ·---- --t----1-= ----H-'d-1--;-+ ---1-1=:r~-__ j ____ _ ==J ______ _ l=-1-===t,---- ------H'---------=i:-__ :j:: ··-t---·-·---· ---- -----1--t:_'1------1---1--- --- -----t--1-- ···--- ---1--·---· , __ _ -----······ 1---1-1-=1= --- :~t=:r.--1=: ---+--1-=---i=--==--===:i ---+--1---1--- ---- I-, __ a::~~:J-=p I ----I -- ---·-+- --+-r-· ·------r---' ·=J::====i-~=t=J-mc_ ----~~_:___ ::-~:;::; ~ ~ = ==== ;t::-: J __ J_ _ ----·-·-- r-----i- I- r-----~--1 ··:=-f=f--r-----,-_1-1--1-1-l=J------<-,--,---___ _,_ H-··-t·---·--·--.. r---i-·. --- I 01cvc Analysis 1' ' I I Specs' Sieve Size % Passfu~ min_ ma,x. 2.so· !00 2.00" 99 1.50" 96 l I/4 94 j 90 3/4" 85 518" 82 112'' 76 318" 67 1/4" 56 114 50 #8 42 #JO 39 #16 )] #30 23 1140 18 #50 15 #100 JO #200 6.7 H11. ~Io, 000 en " w ... f-- wl g; ~ I···--·-·-··· Gni11~ (ll>lll)-t:orps er EQgl11tt"' Urim,m, Sol1C1~Jjnu11.,., ; j~~~ --,- •• 0.1 Materinl: Gray sand and gravel Source: Shamrock Fill 3ample NurnberlDepth (ft~ Classification !Na1. w.c. ILL I ! P.1. !fI.<:jc.-c:: Quality Comrol ---~~;~iL~'.d· ~?41 ?_W•?M. ! I I ' -=---I ! -- fi_~ ,L';,·:--' : ___ 9:p~E o: 5i)Sy-t"' ,.,:.::YGlfJ4 : -<{~ __ --~---- . ·? / .• / / /;/ ?2L--' ,-/A/_,, ~' •-~--·c-:~--).~-~- / .. ;._ ;·:... ;.-. . ~~-, ;:';'o;, ,.;,~k11..-{,;,;;;. ;, ·• ·:.;; :~:..: ~-, •. 1t,, 1 (.•,f.'.',!"O>:· I'•, MAYES TEST I HG Et,tG I NEERS 425 '/45 17:37 Moisture Density Relationship Test ( !i;:n: /l.s~:;oc1,1t,::d Earth SClences Inc. !)~1~1.f7(:·ootrol r; Pjt,·: !,·-,r_'.,,i",·.111,xJ ASTM r., 1557 Method CI ASTM C 127 I D4718 (if needed) ·-,-,.,----· .. ·-·· .. 7,:;;:) \"1iid liur: 1.doticd .ti SpG 2.75 \·!;1~· ! lr·:~·;.ilJ' C"uc,1m.>ct,~d 136.3 -~..,,...,... -·= ·--,~·-=·-----~ ---=<----'', ,, t~·:. ' .. ' ' , ,-j I; ' ' -' I_ I -.-Ll I I ' 1-,, • , •I• I I ) -r=-· .. ":°,-1-• -' I ---· rr._ ___ --' -: ! -. .t·:~-_._ :}.-_ .. ;.;._ ·:; • ; -j-1 i ;.;;: ,J ++ ! t <:·_;_~ ~~--.--:('rt; t I !· ! ·---'--.• I •" • I I ! --: --i-· '._c...: : --Maxir L), ·" :---· ~-· I : ~-I -r- · -..r:.. ---ro..!. :c_ i !~{::}; 1 ; :~ 1-. .-; • . I .. ::.:..+-J+ ! i !-I ! j t [ . I ,_ ·! I ! -- ~_JJ __ . :.~.~:;_:~I •. ~_:._._:;_ '. -; i~~, : i -L . . ' : I \ .I · · ········::_+::::.,, ·h l·i-'· • ·i:. ') 6H • H-·j i·-- --i ' ., ' ' 1-;- . J _, ! I : lJl I . ·:· .·'. _·_ +s __ 1-',-+-r-. +-'--,.-;-e,-<.-,c+++,+-+-t· ,,.: ;r ·: ~ .:! I : ' .· I !--1 : ' , ,.. i-!1 I i .. r-11- 1lO ... , .. , I 11·-·t , ··:. --~-,,_H- ···1·-r: . ,_·_--. --.1.·.1~_"""7)._ ' ; I I !-..... ··] I I-;-;--· ·i ' ' tl + ' . 1-1 . + -1-+-. ' -'--.l ---. . '!'i -' . -!-1' -·+· --1··· ... ·+- ., I ' -I ' ' ' ' --+., _ I I . -I - ··I ,, :~.o 4.0 6.0 8.0 Dare Project Ntn11ber Lab Number 8118/2004 Q4029 (KB O 1508G) 8741 Test Results '' I '' ' ' I '' +I i ' -1- ' ' ,_ ' ' I- ... / . -t--r - . - 10.0 ' -I Percent Retained IS 34 51 ' 1-1-!· 1 1 H--( t· -·:--~ --!-·! . '' I' r·i-1-! :·· '' \ I I I . j· j .. -; ·J : ' I I : : , ··! 11=1-· ': I ! ' '' '!-- ''' ---;· ' i- I-- '' ' '' '' '' '' H- j_-+ W-- '' 1 -f-·1.--H-- . -{.:I-••.. ' ,--~, I; I I I -\ j I ! I - 1\1: I I : \j-'-1- ' I 11 ·-h- ' '' . ' --'-" 1\ • . I 1 ' ----· -1· -H+-.,. 12.0 Water Content, % of clry Weight ,4.0 I 111:,,11111:inn in ll1is r,ipNl .ir!,hes only 10 the octunl snmples lesttd and shall not be r~roduccd except i Engineers, lne s Testing MA YES TESTING ENGINEERS "Wo Mako a l)lllerencaH WETLAND DETERMINATION FOR EAST RENTON PROPERTY Residential Subdivision King County, Washington Prepared for: Ms. Sara Slatten CamWest Development, Inc. 9720 NE 120th Pl. Suite #100 Kirkland, Washington 98034 425-825-1955 Prepared by: C. Gary Schulz Wetland/Forest Ecologist 7700 S. Lakeridge Dr. Seattle, Washington 98178 206-772-6!!14 (April 3, 2001) Revision September 12, 2002 /11troduction Sensitive Area Review Status Project/Site Description Purpose Methodology Wetland Determination Soils Hydrology Wetland Description * Wetland Classification/Connectivity* Wetland Buffer Averaging* Wildlife Habitat Presumption of Salmonid Use* Red-Tail Hawk Nest* Appendix A Data Plot Fonns List of Figures TABLE OF CONTEN1:5 Preliminary Plat -EAST RENTON lntlekofer / Schinnan Property Aerial Photograph -enlarged copy ( I 0-7-00) Boundary/ Topographic Survey map for East Renton (Attached) INTRODUCTION Sensitive Areu Review Stutus This report is a revised version of the preliminary report (Preliminary Wetland Detem1ination for East Renton Property, Schulz 4/3/01) that was submitted with the subdivision application in April, 2002. Most of the first submittal report contents have been retained with no changes to delineated wetland area. King County issued technical review comments (Plat Screening Transmittal, L~nny Henoch 7/1/fYl) for this project and requested additional infonnation that pertains to wetland/wildlife protection and regulations. Responses with additional infonnation and field data are included in this report to be more complete related to the proposed site plan. Wetland data sheets are included with the report. Spcciflc responses to the Screening Transmittal are noted (*) in the Table of Contents and within the written report. Project/Site Deseription The East Renton Property is comprised of 2 parcels with a total size of approximately 19.6 acres situated east of Renton in unincorporated King County. The property is located on the west side of 148th Avenue S.E. near S.E. 120th Street, King County (Section 10, Township 23 N., Range 5 E., WM). The subject property is situated in an area that is zoned for single-family development. The southern parcel (Schinnan property) has been developed for a single-family residence and includes a house and garage/shed. The north parcel (lntlekofer property) has been used for pasture land but includes no improvements except a small shed. The current, project site design has a total of 66 single-family lots clustered on the eastern, upland portion of the property. The project roadway is proposed as a circular access tl!at fronts all of the Jots. Surface water runoff from new development would be conveyed to a detention and water quality facility to be located west of the development. Site plan layout has avoided significant impacts in order to preserve existing wetland areas and associated functions. Please refer to Figure l taken from the Preliminary Plat East Renton (lntlekofer/Schim1an Property-Triad Associates, Inc. 413/fYl). The upper, eastern half of the site is proposed for new, single-family development. This area has flat to gentle sloping topography. Slopes steepen as the site falls to a basin area on the west half of the site. A natural drainage system is present within this basin. Although wetland hydrology is present on-site as groundwater discharge, some surface water flow originates off-site from the south. Seasonal surface water flows through the property to the north boundary where it has been observed to be a seasonal drainage feature. ' (' The majority of the eastern, upland portion of both parcels is pasture land that has not been recently maintained orused. The area includes old apple trees and few, scattered individuals of native bigleaf maple ( Acer macrophyllum), Douglas fir ( Pseudot.rngci memies ii), and western hemlock (T.rnga hererophylla) trees. There is extensive shmb cover of clumps of Himalayan blackberry (Rubus discolor) including one area dominated by Scot's broom (Cyri.rns scopari11s). Waste areas include small trees -crabapple ( Melius sp.) and Douglas' hawthorn (Crataegt,s douglasii). The groundcover is dominated by common pasture grasses and includes areas of bracken fern ( Pteridium aquilim1m). ~· .. · Purpose The purpose of this report is to provide the applicant a complete wetland determination study and respond to requests for additional information. Professional observations are included to assist with detennining natural resource classifications and fuiictions. Wildlife observations, related to red-tail hawk and salmonid fish use, are included in this study. Methodology Typically defined, wetlands are ... 'those areas that are inundated or saturated by surface or groundwater at a frequency and d11ra1ion to support, and that under normal circumstances do support, a prevalence of vegetmion typically adapted for life in saturated soil conditions. Wetlands generally include swamps, marshes, bogs, and similar areas'. Through the State Environmental Policy Act (SEPA) and the Growth Management Act (GMA), the County reviews proposals which may potentially impact wetland and other sensitive areas. Because of observed site conditions, combined with jurisdictional wetland regulations. wetland presence and extent must be determined for the permitting process. The methodology used for wetland detennination was based on the presence of dominant hydrophytic vegetation (i.e .. plant species adapted to, or tolerant of, growing in saturated soil conditions), hydric soils, and observed wetland hydrology as described in the Corps of Engineers Wetlands Delineation Manual (Environmental Laboratory 1987). The Washington State Wetlands Identification and Delineation Manual (Dept. of Ecology Pub. #96-94, 1997) was used, for consistent regional wetland determinations. The State manual was developed to address regional conditions and is consistent with the 1987 Corps Manual methodology. The three technical criteria for vegetation, soils, and hydrology are mandatory under nonnal conditions and must all be met for an area to be identified as wetland. Because the site has relatively distinct wetland plant communities, the Routine On-site Detennination Method was used in this investigation. The current wetland boundaries were professionally land surveyed by Triad Associates, Inc. and mapped onto a base topographic map / i r \ i (lntlekofer/Schirman Property 3/9/0 l). Wetland data plots (9), approximately 0.01 acres 111 size, were installed within wetland and upland areas as a relative sampling of the property's existing conditions. The associated data plot forms are included in Appendix A. ' ,1 I ) WETLAND DETERMINATION Wetland investigations were conducted during middle to late February of 200 I to clelineiite the portions of wetland areas existing on the East Renton Property. Three wetlands (A, B, & C) are identified on the west side of the property and are within the natural drainage corridor that runs from south to north through the property. A total of nine wetland data plots were installed on the project site and this information is found in Appendix A. The Boundary / Topographic Survey map for East Renton (Triad Associates, 3/9/01) includes wetland boundaries and related wetland data plot locations and is attached to this report. To supplement the first submitted wetland study (Schulz 4/3/01), additional investigations of the project site and surrounding drainage basin area were conducted in August, 2002. Several site visits in the immediate area, related to the adjacent Shamrock subdivision proposal, also occurred this summer. Additional information collected from recent site investigations and research is provided in the following sections of this report(*). Soils The SCS (USDA 1973) Soil Survey -J(jng County Area has mapped two soil series on the subject property. The soil map units are Alderwood gravelly sandy loam -0 to 6 percent slopes (AgB) and Alderwood gravelly sandy loam -6 to 15 percent slopes (AgC). The Alderwood series is comprised of moderately, well-drained soils associated with a glacial till at depths of 20 to 40 inches. These soils are on uplands but have inclusions of other soils that are not large enough to map. Some included soils are Norma, Bellingham, Seattle, Tukwila, and Shalcar series. Investigation of portions of the site's upland area confirmed soil that closely resembles the Alderwood series. The soil inclusions mentioned above are poorly drained and found in depression areas and drainage ways on till and outwash plains. These soil map units are listed in the Hydric Soils of Washington (1985). Hydric soils are generally associated with wetland habitats. Hydric mineral soils observed in soil pits excavated within the wetland areas appeared to be the Norma series. Organic soils present in ponded areas could be the Seattle, Tukwila, or Shalcar series. Hydrology King County's Map Folio includes one wetland on the East Renton Property. This wetland is identified as May Creek #24b. The Jetter "b" indicates the wetland was mapped in the US Fish & Wildlife Service National Wetlands Inventory but is not included in the King County Wetlands Inventory (1983). This wetland drains to an off-site "Unclassified" stream identified northwest of the subject property at a distance or more than one mile. This stream appears to be Honey Creek, a tributary to May Creek. Observed hydrology on the site appears directly influenced by local, shallow groundwater that is moving through the area from south to north. There is strong near-surface hydrology within this lowland basin and much or the water may originate on the site. However, contiguous wetland area appears to be present on both south and north sides. Old fann roads, crossing the wetland drainage basin, have caused blockage. As a result, a small and shallow pond has forn1ed on the southwest side of the site. Stream-like channels are present within Wetlands A & B and convey seasonal flows. The concentrated, surface water observed flowing in both of these channels leaves the subject property in two separate culverts placed under an old farn1 road along the north boundary. Wetland Description * Wetlands A, B, and C Wetlands A. B. and C are described together as part of a headwaters wetland system due to their close proximity and similar habitats. On-site wetland drainages have been crossed and separated by fill from old fann roads built on the south and north portions. They are no longer connected by hydric soils but are supported by the same groundwater hydrology through culverts and groundwater seepage. Wetland B is not directly connected to Wetlands A and C on the site; however, surface flows from A and B join just north of the site boundary. The wetland system is within a distinct basin and also receives surface runoff from adjacent slopes. Overall, the wetland areas are characterized as forested habitat dominated by red alder ( A/nus rubra) and black cottonwood ( Populus balsamifera) trees. Several small groves of western red cedar are present along the wetland edge. Big leaf maple and black cottonwood dominate the forest cover in uplands surrounding the wetland drainages. Douglas fir and western hemlock individuals are scattered throughout the basin area. The southern most portion of wetland (Schinnan property) has standing red alder trees throughout; however, the majority are dead and dying and do not constitute significant cover for a forested wetland classification. The shrub cover in the wetland is dominated by salmonberry ( Ru bus spectabilis) and Himalayan blackberry. Past land clearing activities have caused Himalayan blackberry to thrive and dominate in the southern portion of the wetland drainages. Most of Wetland C is affected by blackberry cover. Vine maple (Acer circinatum). red elderberry(Sambucus racemosa), Douglas' spirea (Spiraea doug/asii). and prickly currant (Ribes /acustre) shrubs were also observed in wetland areas. The adjacent upland has dominant shrub cover of Indian plum (Oemleria cerasi/ormis), vine maple, and western hazelnut (Cory/us cornuta) shrubs, Associated upland groundcover is dominated by sword fern ( Polystichum munitum) and Pacific blackberry ( Ru bus ursinus). Creek. Due lo potential wetland connection lo the south, the photos were used to review wetland area to N.E. 4th Street in Renton. Figure 2 is a copy of a photograph used and is included only to display the scale ( l" = 500'), and the watershed area. The results of the aerial photography interpretation arc that no areas of permanent open water exist in the wetland system either on-site or off-site. As mentioned in the wetland description, a small area of standing water was observed on the southwest side of the site. This wetland area has dominant cover of emergent vegetation and is a blocked drainage situation. Also, a small wetland pond exists on the west side of the Shamrock site located to the south. Both of these wetland areas have shallow and seasonal inundation. Recent site visits confim1ed these areas are currently dry. Although the wetland system may exceed lO acres in total size, no pennanent open water is identified and plant associations of infrequent occurrence are not evident. Therefore, because habitat features required for a Class 1 rating do not appear present, this investigation identifies the on-site wetland ratings as Class 2. Wetland Buffer Averaging * The Preliminary Plat site plan proposes a limited amount of buffer reduction along the edge of Wetlands A & B. Per the County's sensitive area standards (KCC 21A.24.320B & Public Rules 21A-24-016), buffer averaging is being proposed in one location on the project site (Figure l). The written analysis to support the buffer averaging is presented as follows. Total Buffer Encroachment 2,575 SQ, ft. Total Buffer Added 4.683 sq. ft. The existing site conditions are relevant to this buffer averaging proposal. The Preliminary Plat Map (Figure I) shows the proposed buffer reductions and additions. Lots 53, 54, & 55 are proposed for buffer reduction. The additional buffer area (4,683 sq. ft.) would be added to Lots 48 thru 52 and adjacent to Tract C. The proposed buffer reduction area is comprised of open forest with dense blackberry understory. This area bas few trees most of which are dead and dying red alder trees. More significant tree cover including mature bigleaf maple is present upslope but outside of the 50-foot buffer zone. The reduced buffer area is relatively small and would not cause a loss of many trees or native shrub vegetation. In addition, the adjacent wetland area was cleared and possibly used as pasture. Currently, it is also an area dominated by Himalayan blackberry. / I f ( The majority of buffer replacement is located within forested areas adjacent to Wetland C. This buffer area is a uniform stand of young to medium age red alder and black cottonwood trees. The added area adjacent to fhe lots provides a higher level of buffer function with potential to increase at maturity. Many trees are present ranging from 4 to 8 inches in diameter that were not surveyed on the topographic map. The buffer averaging, for 2,575 square feet of area reduction, would provide an increase in buffer area that exceeds a ratio of l.5 : I. As a requirement, the buffer averaging would maintain the minimum buffer setback distance of 32.5 feet or 65 percent of the standard buffer width (50 feet). The additional buffer areas are contiguous to the standard buffer. The minimum building setback would be maintained between any strncturc and the reduced buffer (Public Rule 21A-24-016 C). The intent of the proposed buffer averaging is to allow various site design features to occur and meet the code criteria. After site conditions are verified by the County, the buffer averaging demonstrates that total area of buffer does not decrease, some additional wetland protection would be provided, and wetland functions would be enhanced (Public Rule 21A-24-016 A). As part of the buffer averaging analysis, the criteria issues listed in Public Ruic 21A-24-0!6 B were reviewed and are being addressed as follows: I. Preserving the functions of the existing buffer on the parcel and adjoining parcels; 2. Not impacting the stability of a stream bank, if any; 3. Not creating a risk of hazardous trees as a result of development; 4. Providing the opportunity for additional protection or enhancement to the wetlands; 5. Not impacting the location of a floodway and lOO-year floodplain; 6. Not impacting the presence of any migrating river channel; 7. Preserving on-site natural resources (wetlands) and not impacting their functions and values; 8. Health Department requirements for on-site sewage disposal are not applicable to this proposal; 9. Will provide other in.formation to be reasonably necessary to analyze the proposal. In summary, the proposed buffer averaging would provide more buffer area than required by code. Portions of increased buffer area would provide the same or higher function due to existing habitat conditions. No wetland impact is anticipated from the limited reduction of buffer distance m proposed location. .( WILDLIFE HABITAT The projecl site has four distinct plant comm11ni1ies 1ha1 could be i111portan110 wildlife for providing food and cover. These are grassland, shrub, wetland emergent, and forest. The majority of fores! area on the project site will not be impacted by the proposed development. King County has identified protection measures for red-tail hawk use and recenlly requested infonnation regarding the potential presence of salmonids wi1hin the welland / stream system. Red-tail hawk (RTH) use has been identified as a nesting pair using an active nest silc within the wetland system (Schulz 4/3/01). Red-Toil Hawk Nest* The preliminary site investigations located two RTI-I nests (Schulz 4/3/01 ). These have been surveyed and will be shown on the revised Preliminary Plat map. The nests are referred to as the "central' nest and "north" nest. The central nest is in the larges! black cotlonwood tree on the project site but appears to be old and not an active nest (possibly abandoned). During April, 2001 the observations confim1ed the RTI-I were using the north nest. In July, 2002 a site visit verified the RTI-I pair were using the north nest tree. No activity was observed around the central nest. Upon approach to the north nest tree, at a distance of about 200 feet, both RTH were exhibiting defensive and excited behavior. Fledglings were not observed but it could be assumed that at least one offspring was present. Presumption of Salmonld Use * Field observation in early August, 2002 found both wetland channels on the site to be dry. These channels are seasonal drainages, vegetated, and lack gravel habitat and significant erosion features. Although these channels are vegetated with emergent and shrub species, the width of the channels and water influence are greater at the north boundary of the site. It appears that blockage from the old fann road and small culverts causes water to back up at the points of discharge and bas widened the channels. Wetland B's channel is very shallow and has evidence of sheet flow rather than a well-defined stream channel. A limited investigation just north of the project site boundary found an artificial channel to divert and combine wetland surface water flows. The off-site channel is approximately 2 feet wide but at about 30 feet downstream is not evident and becomes wetland pasture. Further investigation observed an shallow swale that is not continuously connected and is disturbed by livestock use. It is not known if barriers to fish movement exist on downstream, private properties. However, this .( area is the uppennost part of the watershed and lacks typical stream features such as perennial hydrology, a gravel bottom, and adequate refuge area, that even resident trout species normally occupy for survival. I' ,I f ( Downstreani at the crossing of 142th Avenue S.E., a forested shrub wetland habitat is present in the depression at about 120 feet wide. A 24" concrete culvert conveys water flow but no distinct channel was observed. This wetland area was also dry in August, 2002. The Stale Department of Fish and Wildlife was contacted on 8/12/02 (Telephone Communication -Larry Fisher. Habitat Biologist) and i'ndicated that it is likely there are no fish in upper Honey Creek but this time of year is not appropriate for an instream fish survey. There is a significant fish barrier downstrearn at 138th Avenue S.E. In summary, using the Public Rules section of the code pertaining lo Salmonid use -Presumption and rebuttal of presumption (KCC 21-24-013) portions of the wetlru1d drainage meet the criteria related to channel width and gradient. Under Public Rules KCC 21-24-013, B., a waiver to the presumption applies using criteria 8.3., 13.4., & 8.5.. In summary, these criteria state there is sufficient information about the geographical region frorn Dept. of Fish & Wildlife to support a departure from the presumption characteristics related to channel width and gradient, and that there is evidence of a cornplete fish banier particularly when the stream has intennitlent or ephemeral flows. Additionally, there may be record of an issued HPA permit from the Dept. of Fish & Wildlife that would confirm the stream area is not used by salmonids. t 0 ( --------------------------------------------------- VEGETATION lndir:ator Dominant Plant~· Slalus Slratum Dominant Plant Spec,es 'ii i~A~/iw.< rm~c;L, .~fi!c-Y;:~ ~~ -k 3. ~~ /. t.dt 13: --- s-i ~: 0£ &i i~ ?.Jcu ,, ~~: ===============· "9¢!=Zf=,$W!!---- 10. 20. Percent of dominant spedas thal are OBL FACW. and/0 ~C /e;t)M ls the hydrophytic vegetation crnerion 'mal? Yes _V_ N N;o __ lndlcalor Status Stratum Aallonale: --------------------------------- la the wetland hydrolO!)y criterion met? Yes No Rllllonale: · JURISDICTIONAL DETERMINATI_9/{AND RATIONALE Is the plant community a wetland? Yes No __ V_ Rationale for'Jurlsdldlonal declslo • !'=-+.-r.d:-..!....:--:;,,--;''-1--,---At,:c:--:,..,---,-f------ 1 This data form can be used tor the Hydric Assessment Procedun,. 2 ClassKlcatlon according to 'Soll Taxonomy." ) ' . ,( ---------------------------------------------- VEGETATION lndk.alor Domlnan~-==n1 Specie+ Statu• Stratum Dominant Plant Specie• ;d 1. ,/ICF,ii,[.~~td fllc_,~1.------ . 2. ~ L../..1 I ~ .j. ./12. ~ ~j !: ~ t( ·-t~.Trihitr ~ tht'lk~!: ;ois. ~~-~~1L ~.' ~U4, 71 1s. ==============· 6. .•. 16,--------- 7. 17. --------- 8. 18. --------- 9. 19. --------- 10. 20. ----~---- Porcent of dominant ,pecio> that an, OBL FACW, and/.e(FAC /a? J, Is tho hydrophytlc vegetation crnerlon met? Yos _V_ N •o __ Indicator Status Stratum Rationale:------------------------------- . Sorie&'phase: . A:~ }'Vz,() L SOILS_< Subgr~up:2 _._. --------- la tho ooll_.on tho nydrlc soils list? Yes __L No V Undetern,lnl>d / IGthq ooll a·Hlstosol? Yos':' No .K_l:l!siic eplpedon pn,aent? YH ,-,.,,::_ No--'::::_ la tho aoll: Mottled?--Yoo,--No ~Gleyed? Yos __ No~ , Matrtx.P,olor: •.. .'~ • Mottle P,,lo Othe.r hydrlc soi · · latho,hydrlc·~n· Ration .... . lo tho ground ourface lnundaz.7':.. a__ No Surface water depth: ---------- lo tho eon saturated? Yos. No ;;J}' Depth to lreo-otandlng water I pit/soil prQbe hole:----==-------------- Uot athor llold ellldonco o1 surface Inundation or sou satu lo tho WC111and hydrolo!IY cnterlon1me1? Aallonalo: 1 This data form c;an be-used for the Hydrlc Soil Assessment Procedure and the Plant Community Aasoaament Prcicedur,,: · 2CCaaaHlcatlon according 10 "Soll Taxonomy." -~- • I ( ' DATA FORM ONSITE DETERMINATION METHOD1 Field lnvostlgator(s): 7/J D t ~ ae: Proj&e1/Sito: State: _ Co ~ un ApplicanVOwnor: Plant Communrty #/Name: Note: tt a more detailed stte description Is nocassary, use tho bad< of data form or a Ii old no Do norll\al.J><1Vironmental conditions exist at the plant community? J_;/. fk I f7 .,. - Yea _JC__ No __ (tt no, explain on back) r//.f__ 7a, 0/ I:? Hes the vegetalion,pl!s, and/or h~drology been significantly dlsturood? ~ /_ ~°£#" 5'/ Yes __ No K_ (tt yes, explain on bad<) Tr I 0 ---------------------------------------·----------- VEGETATION lndlr.ator Indicator Dom~an_! Plant~• Status Stratum DomlnantJtant ~cies , . ~ ~ , 0 9 -)(. ~i 1.~( fiJihl, {'/Iv if.1.p __ 11. ,<Zraw.r.1.JJ:::s:.1tw :< f-PLJ4::,J'ILldi.l J4 ;':~ t~ft: ~;f!r ~ ~ l!: _____ . Jo}~: $&;,hMC!!.5 bicaHlRkl fACJl 11 ~~: _______ _ /~ :: i'2wi .i;;-Z,;c a. FAr u " ~:: ______ _ 10. 20. Porcenl al dominant species Iha! are OBL. FACW~;,{AC &0 ]j b the hydrophytic vegetation criterion met? Yes£ No __ Rationale:------------------------------- Serles/phase: Ycu--; ~ SOILS Subgroup:2 __ _,/::__ ______ _ lo tho aoU on lhe nydrlc soils list? Yes ___,!'lo__ Undetonmln&d tZ / 1G tho ooll a Hlstosol? Yes_·__ No _kZ'Hjpi: eplpedon pruent? Ye& ___L' No _].2' la tho soil: Mottled? Yoo__ No ~!eyed? Yes__ No~ Matrbr .. Co!or: · Mottle P.,lors: --------------- Othor hydrlc so& U)llic1>tors: · la tho hydrlc soR etlter n "}')17 Ration : - HYDRo;.oav lo tho ground aurlace lnunda~? . ••--No i:::::_ Surface water depth: lo tho aoll aaturated? Vos No__ II Depth to troo-atandlng water n pit/soil probe hole:---~,__ _____________ _ Lill! other field ovklen<XI of surface Inundation or soil saturation. le the wed and hydrology crflerlon· met? Yea ....JI'' No __ Rationale: __________ _.:.-'------------------- JURISDICTIONAL J)ETERMINA TION AND RATIONALE la the plant communhy a wetland? Yes _Y_ tJ Nno __ Ratlonalo rorJurlsdk:llonal decision: ----------------------- 1 Thie data form can be uaed tor the Hydrlc Soll Assessment Pr0<:11dure and Iha Plant Community Aa&Gasment ProceduRI. · 2 Claa&Nlcatlon according to "Soll Taxonomy: :> --------------------------------------------------- ill the ground surface Inundated? )'.ri __ ill the soil saturated? Yes _t,c' No __ VEGETATION lndk:.alor S1atus ~ fJ/Cu SMJLJz. 1 VJtu_ 'd>d? JJ HYDROL9(1Y No~ Surface waler depth: ---------- 1 / Depth to free-standing waler In p\Vsoll probe hole: ----..L..--------------- Ust crther field evidence of surface Inundation or soil saturation. la the we!land hydrology criterion me!? Yes V Rationale: t This data form can be used for the Assessment Procedure. 2 ClassK\calion according to "Soil Taxonomy." / ant PrOC9dure and the Plan! Community ---------------------------------------------- VEGETATION Series/phase: Afd~'l'@ql SOILS< Subgroup:2 --------- Is the soil on the nydric soils list? Yes ~o £ Undetermined -..I--/ ls tho soil a Histosol? Yes__ No JL._ fjistic epipedon present? Yes ___£No~ Yes No ---.tL13klyed? Yes__ No~ ------------Mottle Colors:----------~------ HY~R~QY $i Is the ground surface Inundated,? ~--Nol-" __ ~ Surface water depth: ----------- la the sol\ saturated? Yes~ No__ Ji,.// Deplh to free-standing water In.pit/soil probe hole: ----'L'------------------ Ust other field evidence of surface Inundation or soil saturation. la the wetland hydrology crtterlon met? Yes No Rationale: ___ _;;. ____________________________ _ t This data form can be used for the Hydric Soil Assessment Procedure and the Plant Community Assessment Procedure. 2ctassHlcatlon according to "Soil Taxonomy." ,( I --------------------------------- Do norf1)al)'<i'vironmental condttions exist at the plant communtty? Yea _JL._ No __ ( o, explain on back) Has the v9<,1etalion, s , and/or hydrology been si,;inificanlly disturti.>d? Yes No (tt yes, explain on back) ------------. -------------------------------------- VEGETATION . . , HYDROl,OOY Is the ground surface Inundated? )I(.__ No-~--Su ""rface water depth: Is the soil saturated? Yea _IL No__ _ Depth to free-standing water In pit/soil probe hole:-------------------- List other lleld evidlence of surface Inundation or soil saturation. / Is the wetland hydrology criterion met? Yes :..Z No __ Rationale:--------------------------------- t This data form can be used for the Hydrlc: Soil Assessment Procedure and the Plant Community Assessment Procedurn. 2 ClassHlc:atlon according to "Soil Taxonomy." ( ) ,( I --------------------------------------------------- VEGETATION If HYDROL90Y la the ground surlace Inundated? Yes ~_..,.,..,_ "S•u•rface water depth: ---------- lo tho soil saturated? Yes__ No~ - Depth to free-standing water In pil/soll probe hole:-------------------- List other field evidence of surlace Inundation or soil saturation. la the wetland hydrology criterion met? Yes No Rationale: ______________________________ _ · JURISDICTIONAL DETERMIN9CN AND RATIONALE la the plant community a wetland? Yea__ No _t..,,/ __ Rationale foljurlsdlc!lonal decision: · 1 This data form can be used for the Hydrlc Soil Assessment Procedure and the Plant Community Aseeasment Procedure. 2 ClassHlcallon according to "Soil Taxonomy." ( ( , ·r. ... ·-_.~, ·-. --~···--. . -------------------------- VEGETATION. lndk-.ator Domln!'ll_ Plant~· Sia)uo Stralum Dominant Plant Specie• ex 1 "/0 1. /JIJx>.d lifu. d , tA c.-we 11. ------- * fS'oi ~j'iik,:< di?c.d;w-f)Oil ~~;: ------ 4. ... . .. · 14. --------- 5. 15. --------- 8. 16. --------- 7. 17. --------- 8. 16. --------- 9. 19. --------- 10. . ' 20. ~ Porcent ol dominant species that are OBL. FACW, and/or FA9L~Y'-'C)"-",0=----- 1$ tho hydrophytlc vegetation criterion mot? Yea __ . No L_ . Indicator Status Stratum Rationale:-------------------------------.. ,, ... ·· ... •· ... • • C .,,, HYDRO~Y . ,'· . lo tho ground aurlacx, inundated?\ ~-· --. No JL. Sur111CO water depth;,,_. --------- lo tho uoH aatura1ed?'.:'Yoa----'.::"' No__ /e; 11 DopCh to froo·utandlng.water rn pltisoll probe hole: ---~-<...:'--------------- list Olhor flold evldenco·ot surface Inundation or soH a'9'tlon. lo 1ho woUand hydrology'crtterlon• met? Yea V No -,,.. ~ ... h r Rldlonalo: • ~~~('I,.,, I This data form can bo used for the Hydrtc Soll Assessment Procedure and lho Plant Community Auaoaoinent Proc:oouro. · 2 Claaafflcotlon according to 0 SoH·Taxonomy." ( ' • .. ,, ! ' } -------------------------------------------------- Do_norm,al j!Wlronmental condttlons exist at the plant community? Yeo·~ No __ (tf·no, explain on back) Hu the-vegetatlon,JSl!s, and/or hydrology been significantly disturbed? Yes __ No _V_ CH (ti yes, explain on back) --------------------------------------------------- VEGETATION- Indicator Indicator . ). Do~~tP\ant :7+ Status Stratum Dominant Plant Species /&';J 1,/l[W5 kb,.J:o', fi{c.. ffe t ti.------ Slatua Stratum . · 2; -'------,-----12. ---------* µ):~A0¥u, rLi cohk-: f,bi. <fiN.b ~~ __ __:__~ 5 ------------15. --------- ··L··-;..;· ------~--18. --------- 7. ,_, ... _ 17. ---------a.·_________ 18. --------- 9. ---------19. --------- 10. --------20. --~-~9---- Porcent of dominant species that are OBL FACW. and/or FAC k (/IO la the hydrophytlc vegetation criterion mot? Yea_· _ No -1Z.. _ _._ Rationale:------------------------------- . --.-,.;· .... ,-~ .. :_'~= ~~u;:';,:~ln~~~i=== =-~-0 __ ;u]a~ ;a:er:;~/ _________ _ Oopth to troo·olandlng wator In pit/soil probe hole: __ ..,././aJ.""-'~t'.}:..i.:,':{;../«... ___________ _ Uot athor flak! evldonco o1 surface Inundation or soil saturation. bl tho weUand hydrolo!IY criterion• met? Yes JZ.. < No __ l~~ Ratlonalo: · · · . ct / JURISDICTIONAL DETERMINATION AND RATIONALE -} lo tho,plant ~mmunlty a weUand? Yoa __ No V- Ratlonolo to,:Jurladlcllonal deelslon: -------.ICl1.'..J!.A--l:¥-,:.ldi~~A!o~~c::.r:.i::>.L...!,:JL./ t TIiis data form can bG uaed tor the Hydrlc SoU Asseaament Procedure and tho Plant Community Aauoment Procodulll. · · · 2 ClaaaKlcatlon according to "Soft Taxonomy." ·-~ f ( I I 1 /'. ~· t -~" . / ' I '·· '< l ,/ ' l / "' 7' ~,,r, l I / ~ \ t ! Figure 1 -I /' "'.;, ' RICK M & DEBRA L CRUU ~ ! s . t p I l 1-----·-····-·--··---·--·--·------·----· 1· CY'. ' 11813 148TH AVE SE r, :1 1 e an I I . 1%, \ RENTON. WA 98059 ~,=,£ .,,yJ: .... _ i I ~~~ \\ r,rn='l "t1-t:f 11 I ) n r l I ~H E & TINA M KIGER )26 142ND A VE SE RENTON, WA 98059 l I ! ' ' 4!'" ,.,, ID & · }(> r,-4 ! / ~ Lu.,,.cllL<f:l I 1.,, ~VJ I/ Fi 'N, 1 2· REBAR If CAP ~ \ jl.·.· ... :) ! IN C BENT TD £AST -1< rn,,, .~JJc.' 1; 1 Ls /5524 ~ • _ r ~ , < ·.·.·.·. J. •jt s. o.p' &: £ .. 0.06' ~ EX JO COTTONWOOD \l LOt I '<,,,"'";! .le,£. I >. ·.·.[;[ ;' I .. 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' ',/-' ·. ,.., .. : 1 • 12~ • -• • : • .· • ,iio-_ , · iiJ ~ 36 sij 25 .. Sl ·5 :l;x: I .. ,_1 ,:;~: __ \_, __ ._.·· ·'-" ·t .. ··.-J~:--/-·_,.. 1 // .. ,; 0:.····_.·",,·. ~.-·.-.. 4J, .. ····.··ift!/"' ~.·-100 _ ·I,;; _ ··,-,-IQL. ,:~ I i . : , ~!;~ . . . :__ \ \ ,,, . '_).-. ~ I. • 48_ . ~ ~\ . ~ . . .· . ., .· : . . b ~. ~ j5 ~-26 ~ 4 ~ .. ( .;/(· ··~.·,:·.. _·.· 4' ..... ,,---·-f ,•11· •01, .·o,"' .46 ': J8 "' .... ·_wo-I wo --.. ~:· .,1· I• ............. ·-__ ,.. ~ . ( . . . . . . -~ . ·. . • .. ,.· ·------"--........ : ......... ',,, .... , •/• • ~.;1 ·,9 : . .:.....;,fil_, .• . • • ,p·· !. , . ., \ • • ~d.::, .,.. _V, , -Cl J J 0. C> ••, '1' . . , '· -: · :r 1 ·-• . ., .,. "' 27 "' ;,, .., ; 1 . . , 50 .Well.AND , .,. 0 . . . • I I , ( , \. ·.. ~-( :U'~t _!Q,_ 45 . ,sl 3g 14:. _100-,9o .. tr:· . ~:_. ~ ! /· , " , , .,-·[® I . 112 '1 . !O K . I ·1·· ,"'-· ·, : \ ~\1\;t,, '50 ·-.-... . 10, i· o i:, i:, ·o , . " • • . '\ : , . . . . . .:{{,' 0 1-' • . . . . • . . 0 JJ ,,. 28 "' '0 2 ·. ..· ·._ -; .. , : \ . -1'n:-. ~ 4#-• . . , .4() • -1 ,po· I lpG' . 105-.. .-·-. . • ~ • ~ ""''° ~ : ,i -J P.:W (t} . ; ~9-' ' : : , i ,06· \ . . · . -. -.. -. -· '2 • · · • · : ' ' '"'\ I~ 120' ' -4· ,· • · · ' ) .. .:" / · TJr;t,1\fj()J:,,,[.:· .. t ~)·' / f'm, ~:~, 51_ ;8~, , ss·n---· , io 32 . ~' 29 ~ ~ 1 . .,, I : , "1l.' l,'w;,q . ..1iU..,_ , : ; ; ' • ; • • ; "' IPO' ' I ... 1pG' -1.&_ __ll,I.Y '\ , • . • ; ·tey. \ . . . ~·T. ':., ; 2· -;_ : 41 ~ I I "> , . '\, · ~ · ·. ·· +; ,J · 1',"'\ 2 ;~, ;o,: ,4 0i· : · IQ • • o I f"I --·---=.::· . ...:__~--· .... f~q-JTW),__:_,-+--.... ·-. -~.......:-_~t;.~--~ --'; . ' . : ~ ;1 . ; . "l: Jt .' ~ JO • .--·--···~---·· ·.·--,··-·----·· ······--·-- M & KATHRYN M JO/INSDN 12006 142ND A VE SE !ENTDN, IYA 98059 ----... , ................ _..,......"""' :1< M & KATHRiiv M ."ll/NSON 12onfi 142ND A VE SE RENTON, WA 98059 ,. <..\· (."> - ,;. '.? \" • ,J• ...i • •• • ,J ~ ,• 121' ,. .• ...;.-.:....,... ·-···~ -. -:·--;. ··-. .· ·-·:·--· --~~ ---.. < -.,._ . L ~ :. ' ~ ': •... ) ,J• .. ,F• /,{\, -. . ;lJ . , · SS' ; 7': i.0_' ; '-1,; 16'. : ;4. -~~- . ' ,,, ' --~· 5 ' 1'1£/LAND ·: . ·. . L , :S~-. SJ . _ li : ·• : , ; '-" ._._, . ; , , . . ·. ·. , • I !J5.20Q'. _ ' , /f-, ., ·. BUFFER T'rP : ,, ' , ;'.,Ii. , . ',j, -.-,---:c . ~ 12 0 -81 -, -,,. , --.___.;1::: , 1 . .,. --/il :". • : \ '1··· -J •j· • .'. -:.-.~:., C> . : ':' l . . l . . R=20{!. I <:_..; ·. \. .,.WE:TLANO A ' : ·., -. WE:TLAND C ._·._l ,· ~.\';\ • '. ,' ·:' ·. , . .. ·. §·. '· ~5·. 50; i so' 5o' 50' .,o· . so· I so --50· -I 50'1 _1_s "'j' ,- . ,. (TYPE II) ·. • • (t'YPE II) · /J .· ·54 ·. ·, ~ , · · · -' -, 1 1 1 , ., , I • • .::f··'l; •":I. 0"!~,r<-;-,i;:·,:·>:,; • ,f:'.':: .. -{' : ' • , ' , • , .' ~ , -I \ -,CQ l . '-... I . ''.''lih'·" ,,,wf ',, ), ; ... .,\ 1. too . . . . . . '"' .. ·<> '" '"9" 0 0 '.c. . ,., -~, ('F;;\IO ,I + 1 ' : r-P\J\, \P},,, · : ,1;, . · '." · · .· : ' , ' 56. •'2· '57 'i!.· 58 '2 -. ;;, '2-60 '2 61 2 62 "-6~ ls 64 '/!, -55-'2 WIO / / ~ y I . " '4) 55 '. /,' ~. -!I · j ' 1 ·· LlL.1 -~--l--'.~-----, ,_..,.: ' I -·~--· j9£" . t ·~·-t ; ', J• r-.• i 2.. ·. ·.·9.Z..... ' . ' ··. ' J·.;..1.. ,o'' so',._ . _J,G' .. so-: 0 . l, /-~j~---. ; --------II N88'2004.--W 1294;39' ' ' · • , · · · · .. ···· · "' -~ 50 sci. 5V' I 6J' \ ' ,:)'.,. . . 6 . 6 "' . . . I i I I I '• <J to t-, C'D 1.,) \) c, I \ I\ ·1' ~-,:: \):i t:.. ,.: I ~-~ ir1 , \ ,, , 1 BUFFER IMPACT AREA C) ;, I, \ \ • I THERESA HELEN GACEK. ET Al. APPROXIMATE LOCATION OF )---, ~ I'··-l . TI f I 2823 16TH S EXIS77NG STRUCTURE (TYP) I ) I__ I r· I · ·::< ·• 1 · .,·. ! I SP.1M'f.R R-',1 .QR14d ---~ -~ 1 I ,, .,. ~-.. I -,, t I ., ) ' /, East Renton/Rosemonte -Technical Information Report 7 OTHER PERMITS o FPA o NPDES Job #01-047 August?,2008 /r.IDAP. ---- Page7-1 East Renton/Rosemonte -Technical Information Report 8 TESC ANALYSIS, DESIGN AND CONSTRUCTION STORMWATER POLUTION PREVENTION PLAN Temporary erosion and sediment control (TESC) measures such as Clearing Limits, Cover Measures, Perimeter Protection, Traffic Area Stabilization, Sediment Retention, Surface Water Controls, and Dust Control will be implemented according to Best Management Practices (BMPs). The clearing limits will be flagged prior to beginning any construction activities. The downhill perimeters of clearing will be protected with double filter fabric fencing, and other perimeter protection methods as required. Cleared areas will be stabilized with various cover measures as required ( e.g. temporary/permanent seeding and mulching,). Stabilized construction entrance will be provided at the construction accesses to the site. Interceptor swales will be installed to collect and route runoff from the disturbed areas to a sediment pond or to sediment basins that recharge the wetlands. The sediment basins will act like and are sized according to sediment traps. Dust control measures will be implemented if there is a need (i.e., if there is a particularly dry period during construction). The permanent pond with control structure is to be installed during the early start grading phase and no temporary sediment pond riser is to be installed. Peak runoff rates used to size sediment control facilities were determined using the KCRTS program. Parameters used for the program were a Scale Factor of 1.0 Seatac, till soils, and hourly time steps. TESC Measures were designed per Section D.4.5 -Sediment Retention of the 1998 KCSWDM. 8.1 Sediment Basins The sediment basins have been sized for the area draining to them with cleared and graded conditions. The required surface area for a sediment trap has been used for sizing the basins and was computed using the JO-year developed peak flow rate considering cleared conditions. A summary of the erosion control calculations for the sediment pond is provided below. See the end of this section for TESC PLAN AND EARLY GRADING TRIBUTARY AREA EXHIBIT. Job #01-047 August 7, 2008 Page 8-1 East Renton/Rosemonte -Technical Information Report Basin B Till Grass Impervious KCRTS Peak Flow Flow Frequency Analysis Time Series File:trapb.tsf Project Location:Sea-Tac 0.79 acres 0.03 acres ---Annual Peak Flow Rates--------Flow Frequency Analysis------- Flow Rate Rank Time of Peak --Peaks Rank Return Prob (CFS) (CFS) Period 0.078 4 2/09/01 2:00 0.181 1 100.00 0.990 0.042 7 1/05/02 16:00 0.098 2 25.00 0. 960 0.098 2 2/27/03 7:00 0.080 3 10.00 0. 900 0.022 8 8/26/04 2:00 0.078 4 5.00 0.800 0.044 6 1/05/05 8:00 0.073 5 3.00 0. 667 0.080 3 1/18/06 16:00 0.044 6 2.00 0.500 0.073 5 11/24/06 3:00 0.042 7 1. 30 0.231 0.181 1 1/09/08 6:00 0.022 8 1.10 0. 091 Computed Peaks 0. 154 50.00 0. 980 Surface Area (SA} The peak flow used to size the surface area of the sediment pond was conservatively chosen to be that of the I 0-year storm event instead of the 2-year storm event. Required Pond Surface Area = 2 x (Q10/0.00096) = 2 X (0.080/0.00096) = 167 sf TIie Required Sediment Trap Surface Area is 167 sf. Basin C Till Grass KCRTS Peak Flow Flow Frequency Analysis Time Series File:trapc.tsf Project Location:Sea-Tac 0.44 acres ---Annual Peak Flow Rates--------Flow Frequency Analysis------- Flow Rate Rank (CFS) 0.039 4 0.020 7 0.050 2 0.008 8 0.021 6 0.040 3 0.036 5 0.093 1 Computed Peaks Job #01-047 August 7, 2008 Time of Peak 2/09/01 2:00 1/05/02 16: 00 2/27/03 7:00 3/24/04 19:00 1/05/05 8:00 1/18/06 16:00 11/24/06 3:00 1/09/08 6:00 --Peaks Rank Return Prob (CFS) Period 0.093 1 100.00 0.050 2 25.00 0.040 3 10.00 0.039 4 5.00 0.036 5 3.00 0.021 6 2.00 0.020 7 1.30 0.008 8 1.10 0.079 50.00 0.990 0. 960 0.900 0. 800 0. 667 0.500 0.231 0.091 0.980 Page 8-2 East Renton/Rosemonte -Technical Information Report Surface Area (SA) The peak flow used to size the surface area of the sediment pond was conservatively chosen to be that of the I 0-year storm event instead of the 2-year storm event. Required Pond Surface Area = 2 x (Q,o/0.00096) = 2 X (0.040/0.00096) =83 sf The Required Sediment Trap Surface Area is 83 sf. Basin D Till Grass KCRTS Peak Flow Flow Frequency Analysis Time Series File:trapd.tsf Project Location:Sea-Tac 1.91 acres ---Annual Peak Flow Rates--------Flow Frequency Analysis------- Flow Rate Rank Time of Peak --Peaks Rank Return Prob (CFS) (CFS) Period 0.171 4 2/09/01 2:00 0. 4 04 l 100.00 0.990 0.087 7 1/05/02 16:00 0.217 2 25.00 0. 960 0. 217 2 2/27/03 7:00 0.175 3 10.00 0. 900 0.036 8 8/26/04 2:00 0.171 4 5.00 0.800 0.094 6 1/05/05 8:00 0.157 5 3.00 0. 667 0.175 3 1/18/06 16:00 0. 094 6 2.00 0.500 o. 157 5 11/24/06 3:00 0.087 7 1. 30 0.231 0. 4 04 1 1/09/08 6:00 0.036 8 1.10 0.091 Computed Peaks 0.342 50.00 0.980 Surface Area {SA) The peak flow used to size the surface area of the sediment pond was conservatively chosen to be that of the I 0-year storm event instead of the 2-year storm event. Required Pond Surface Area = 2 x (Q,o/0.00096) Job #01-047 August7,2008 = 2 X (0. J 75/0.00096) = 365 sf The Required Sediment Trap Surface Area is 365 sf. Page 8-3 East Renton/Rosemonte -Technical Information Report ) 9 BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT 9. 1 Bond Quantities A Site Improvement Bond Quantity Worksheet will be provided at the end of the engineering review process. 9.2 Facility Summaries Enclosed at the end of this section with reduced size pond sheets. 9.3 Declaration of Covenant Not applicable. Job #01-047 August7,2008 Page 9-1 KING COUNTY. WASHINGTON, SURFACE WATER DESIGN MANUAL STORMWATER FACILITY SUMMARY SHEET Development East Renton/Rosemonte Date August 5, 2008 Location West of 148 111 Ave SE between SE 118'11 St and SE 120'11 St. ENGINEER DEVELOPER Name Sheri Murata, PE Name Jennifer Reiner Firm Triad Associates Firm Cam West Real Estate Development Inc Address 12112 115th Avenue NE Address 9720 NE I 20th Place, # I 00 Kirkland, WA 98034 Kirkland, WA 98034 Phone ( 425) 821-8448 Phone(425)825-1955 Developed Site: Acres 17.87 Number of lots 21. Number of detention facilities on site: Number of infiltration facilities on site: l ponds Q ponds Q vaults Q vaults Q tanks Q tanks Flow control provided in regional facility (give location) ___________ _ No flow control required Exemption number __________ _ I) ownstream D . rainage B asms Immediate Major Basin Honey Dew (Honey Creek) Cedar River Number & type of water quality facilities on site: ___ biofiltration swale (regular/wet/ or continuous inflow?) l Basic combined detention/WQ pond (WQ portion basic or large?) combined detention/wetvault --- ---compost filter ---filter strip ~'=3 __ flow dispersion ___ farm management plan ---landscape management plan ___ sand filter (basic or large?) ---sand filter, linear (basic or large?) ___ sand filter vault (basic or large?) stormwater wetland --- ---wetpond (basic or large?) wetvault --- Storm Filter Manhole --- ---oil/water separator (baffle or coalescing plate?) catch basin inserts: Manufacturer --------------------- ___ pre-settling pond ___ pre-settling structure: Manufacturer ________________ _ --'----flow-splitter catchbasin 1998 Surface Water Design Manual 1 9/l /98 KING COUNTY. WASHINGTON. SURFACE WATER DESIGN MANUAL I DESIGN INFORMATION Water Quality design flow n/a Water Quality treated volume or 59,267 cf wetpond Vr DESIGN INFORMATION, TOTAL cont'd Drainage basin(s) Area/ Flow Bypass Released Onsite area 16.94 14. 73 2.21 Offsite area 0.93 0.93 Tvoe of Storage Facilitv Pond Live Storage Volume 105.292 cf Predeveloped Runoff Rate 2-year 0. 751 10-year 1.31 JOO-year 242 Developed runoff rate 2-year 2.94 0.188 0.748 10-vear 3.54 0.280 1.30 I 00-year 5.94 0.588 4.23 Type of rcstrictor Riser Diam. of orifice/restriction No. I 3.63 No. 2 3.25 No. 3 9/1/98 1998 Surface Water Design Manual ?. KING COUNTY, WASHINGTON. SURFACE WATER DESIGN MANUAL FLOW CONTROL & WATER QUALITY FACILITY SUMMARY SHEET SKETCH All detention, infiltration and water quality facilities must include a sketch per the following criteria: I. Heading for the drawings should be located at the top of the sketch (top right-hand corner). The heading should contain: o North arrow (point up or to left) • 09# o Plat name or short plat number o Address (nearest) • Date drawn ( or updated) • Thomas Brothers page, grid number 2. Label CBs and MHs with the plan and profile designation. Label the control structure in writing or abbreviate with C.S. Indicate which structures provide spill control. 3. Pipes--indicate: Pipe size Pipe length Flow direction Uses single heavyweight line 4. Tanks--use a double, heavyweight line and indicate size (diameter) 5. Access roads • Outline the limits of the road o Fill the outline with dots if the road is gravel. Label in writing ii'anothcr surfocc. 6. Other Standard Symbols: • Bollards: o o o o c c c c • Rip rap 000000 000000 Fences --x---x---x---x---x---x--- • Ditches -o-CD-Co--CD 7. Label trash racks in writing. 8. Label all streets with the actual street sign designation. If you don't know the actual street name, consult the plat map. 9. Include easements and lot lines or tract limits when possible. I 0. Arrange all the labeling or writing to read from left to right or from bottom to top with reference to a properly oriented heading. · 11. Indicate driveways or features that may impact access, maintenance or replacement. 1998 Surface Water Design Manual 9/1/98 NOl!JN/HSVM iUNno::i 9Nl)I i 1 ~~ I ' ; I ~\ ~JJ.IMO!ll:73$J()jjj / IMOJ1/M3/Sil J1S~3/ u.i "' w <., a: (.) w U) ;; ..J ..J < w z w :c ... u. 0 .. ;:, w U) w :c ... "' "' ;:, w U) w :c ... u. 0 .. ;:, w z w :c ... u. 0 a: 0 Q. l ! I ' -€tP-" N ,_ w ~ 1J ' "' ------- ·--..... __ -_-=--.:..-=----~ -------------- ,.---- ----·' -,/_,-,----. .... , _,,:_-+ ,' ,,,' \ ----,---\. //,, I I ' ,' I / ,. ,--- \-> ; -~ .LN3Wd013!130 .LS3MW1t::> \~ ·~ ', ,' ' ' \' ' Nlt1d ONOd I ' \ .' ·' /\. '.' \ ·\ ' ' ,. ' ' ' ' ' I I ' .\ \ \ '\ \ \ \ iJ if '! I '/ I' .I i,\ tii$ Ii~ .. ;; .. }, b':a:: '' .r ' ' I " ' ' ' ' ' ' ' ' ' : \~-~- :·-:. 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Job #01-047 August?,2008 Page 10-1 Q-~STONE ·,·1~ "'7nETAININGWALLSYSTEMS RETAINING WALL DESIGN Version 3.5.1 Build 124 SEISMIC DESIGN, Div!, Chap 5 Layer 2 I Projed: Rosemunte -East Renton Project No: KE040766B Case: Case I Design Method: AASHT0-96 (modified soil illte,face) Design Parameters Soil Parameters: Reinforced Fill Retained Zone Foundation Soil Reinforced Fill Type: j_ 32 36 32 Silts & sands _f_ 0 0 0 1...1!£! 120 135 120 Date: 8/712008 Designer: SGB Unit Fill: Crushed Stone, I inch minus .. I Peak Acceleration= 0.2 Jg Vertical Acceleration= 0.00 g Factol's ofSafety (seismic are 75% of static) sliding: I.SO/LI 3 pullout: I.SO/LI 3 tmce1tainties: 1-50/1.13 J.50/1.13 LOO/NA overturning: bearing: 2.0011.50 2.00/1.50 shear: bending: 1.50 1.50 Reinforcing Parameters: Strata-Grid Geogrids SG350 Tult 4350 RFcr 1.61 RFd uo RFid 1.05 LTDS 2339 A11alysis,Wa/l No. IA 5' with 2:1 slope above for 8/eel Ullit Type: Stalldard 21.5"/ 120.00pcf leveling Pad: Crushed Stone Wall Ht: 5.00ft BackS/ope: 26. 00 deg. slope, Surcharge: LL: 0 p.:,funiform surcharge Load Width: I 00.00 ft Results: Sliding Overtuming Factors of Safety: 2.5411.48 5.3//2.78 Calculated Bearing Pressure: 7291729/940 psf Eccentricity at base: 0.16 ft/0.66 ft Reinforcing: (ft & lbs/ft) Height 3.33 1.33 Length 50 5.0 Cale. Tension 160 /366 397 1725 Reinf. Type SG350 SG350 Reinforcing Quantities (110 waste included): SG350 1.11 sy/ft connection: Serviceability: FS Tai Ci 1.50 1560/3348 0.90 Case: Case 1 Cds 0.90 Wall Batter: 4.40 deg. embedment: I. 00 ft 8.00 ft long DL O psf uniform surcharge Load Width: 100. 00 ft Beariug 15.44110.07 Allow Ten Tai 1560/3348 ok I 560/3348 ok Shear 12.75 /6.80 Pk, Conn Tel 1160/1547 ok 1265/1686 ok Bemliug 9.91 /1.85 Serv Conn Tse 12,72/.NIA ok 1~461 NIA ok NOTE: THESE CALCULATIONS ARE FOR PREl/MlNARY DESIGN ONLY AND SHOULD NOT BE USED FOR CONSTRUCTION WITHOUT REVIEW BY A QUAl/FIED ENGll'(EER Date 8f7/2008 / ~- _·..; ' £ Pullout FS 4.57/1.60 ok 4.37/1.92 ok Page 1 \l~STONE ~ ~R'aAJNINGWALLSYSTEMS RETAINING WALL DESIGN Version 3.5.1 Build 124 SEISMIC DESIGN, Div!, Chap 5 Project: Rosemonte -East Renton Project No: KE040766B Date: 8/7/2008 Designer: SOB Case: Case I Design Method: AASHT0-96 (modified soil inte,face) Design Parameters Soil Parameters: Reinforced Fill Retained Zone Foundation Soil Reinforced Fill Type: j_ 32 36 32 Silts & sands ..£.. 0 0 0 Unit Fill: Crushed Stone, I inch minus ..Lil£f 120 135 120 Peak Acceleration= 0.21 g Vertical Acceleration= 0.00 g Factors of Safety (seismic are 75% of static) sliding: l.50/1.13 pullout: overtwning: 2.00/1.50 shear: bearing: 2.00/1.50 bending: Reinforcing Parameters: Strata-Grid Geogrids SG350 Tuft 4350 RFcr 1.61 RFd I.JO RFid 1.05 A11alysisiVal/ No. JB 5.67' with 110 surcharge l.50/1.13 1.50 1.50 LTDS 2339 Unit Type: Standard 21.5" I /2000 pcf Leveling Pad: Crnshed Stone Wall Ht: 5.67 ft Level Backfill Offset: 0.00 uncertainties: connection: Serviceability: l.50/1.13 l.50/1.13 1.00 /NA FS Tai Ci 1.50 I 560/3348 0.90 Cds 0.90 Case: Case 1 Wall Batter: 4.40 deg. embedment: I. 00 ft Surcharge: LL: 0 psf uniform surcharge load Width: 100.00ft DL: 0 psf uniform surcharge Load Width: I 00. 00 ft Results: Sliding Ovel't11mi11g Factors of Safety: 4.8912.07 /2.87/4.09 Calculated Bearing Pressure: 686 I 686/838 psj Eccentricity at base: 0.13 ft/0.65 ft Reinforcing: (ft & lbs/ft) Cale. Layer Height Length Tension 2 4.00 6.0 119 /350 2.00 6.0 4/81745 Reinf. Type SG350 SG350 Reinforcing Quantities (no waste included): SG350 1.33 sy/ft Beal'i11g /9.20/13.49 Allow Ten Tai 1560/3348 ok 1560/3348 ok Shem· 16.95 /8.69 Pk Conn Tel 1160/1547 ok /265/1686 ok Be11di11g 13.28 12.46 Serv Conn Tse 1272/ NIA ok 1346/ NIA ok NOTE: THESE CALCULATIONS ARE FOR PRELIMINARY DESIGN ONLY AND SHOULD NOT BE USED FOR CONSTRUCT/ON WITHOUT REVIEW BY A QUALIFIED ENGINEER Date 8/7/2008 Pullout FS 435/1./8 ok 3.8511.73 ok Page 1 i~STONE th.. ~IITTAINING WALL SYSTEMS RETAINING WALL DESIGN Layer 4 3 2 Version 3.5.l Build 124 SEISMIC DESIGN, Div!, Chap 5 Project: Rosemonte -East Renton Project No: KE040766B Date: 8/7/2008 Designer: SGB Case: Case I Design Method: AASHT0-96 (modified soil inte,face) Design Parameters Soil Parameters: Reinforced Fi/I j_ 32 36 32 ..£. 0 0 0 ..Y....J!£[ /20 /35 /20 Retained Zone Foundation Soil Reinforced Fill Type: Silts & sands I L• 9.SOl'I I IQ ~ I Unit Fill: Crushed Stone, I inch minus Peak Acceleration= 0.21 g Vertical Acceleration= 0.00 g Factors of Safety (seismic are 75% ofstatic) sliding: l.50/1.13 pullout: overturning: 2.00/1.50 shear: bearing: 2.00/1.50 bending: Reinforcing Parameters: Strata-Grid Geogrids Tull RFcr RFd RFid SG350 4350 l.6/ 1.10 1.05 l.50/1.13 1.50 1.50 LTDS 2339 A11alysis.Wa/l No. 2 12.33' with traffic s11rcharge Unit Type: Standard 21.5" I 120.00 pcf Leveling Pad: Crushed Stone Wall Ht. 12.33 ft level Backfill Offset: 5.00 uncertainties: connection: Serviceability: l.50/1.13 l.50/1.13 1.00 /NA FS Tai Ci 1.50 1560/3348 0.90 Cds 0.90 Case: Case 1 Wall Batter: 4.40 deg. embedment: 3.00ft Surcharge: LL: 150 psfw1iform surcharge Load Width: 100.00ft DL: 100 p.!.f uniform surcharge load Width: 100.00ft Results: Sliding Overturning FactorsofSafety: 2.7611.45 4.86/2./2 Calculated Bearing Pressure: /69/ I /697/2549 psf Eccentricity at base: 0.60 ft/2.08 ft Reinforcing: (ft & lbs/ft) Cale. Height Length Tension Rcinf. Tyl!e /0.67 9.5 /50/414 SG350 8.00 9.5 386 I 778 SG350 5.33 9.5 624 I 1144 SG350 2.67 9.5 /4/9/2021 SG350 Reinforcing Quantities (110 waste included): SG350 4.22 sy/ft Bearing 13.83/7.07 Allow Ten Tai 1560/3348 ok I 560/3348 ok 1560/3348 ok J 560/3348 ok Shear 5.3913.48 Pk Conn I£! 1/60/1547 ok /299/1732 ok /438119/8 ok 1577/2/03 ok Betiding 8.45 12.47 Serv Conn Tse 1272/ NIA ok 1371/ NIA ok 1470/ NIA ok 1569/ NIA ok NOTE: THESE CALCULATIONS ARE FOR PRELIMINARY DESIGN ONLY AND SHOULD NOT BE USED FOR CONSTRUCT/ON WITHOUT REVIEW BY A QUALIFIED ENGINEER Date 8/7/2008 Pullout FS 5.84//.70 ok 6.98/2. 77 ok 8.6913.79 ok 6. 3813. 58 ok Pagel Layer I RETAINING WALL DESIGN Version 3.5.1 Build 124 SEISMIC DESIGN, Div!, Chap 5 Project: Rosemonte East Renton Project No: KE040766B Date: 817/2008 Designer: SOB Case: Case 1 . Design Method: AASHT0-96 (modified soil interface) Design Parameters Soil Parameters: Reinforced Fill Retained Zone Foundation Soil Reinforced Fill Type: _l 32 36 32 Silts & sands s.. 0 0 0 Unit Fill: Crushed Stone, I inch minus ..LJl£f 120 135 120 Peak Acceleration= 0.2 I g Vertical Acceleration= 0.00 g Factors ofSaf'ety (seismic are 75% of static) sliding: l.50/1.13 pullout: ove,tuming: 2.0011.50 shear: bearing: 2.00/1.50 bending: Reinforcing Parameters: Strata-Grid Geogrids Tuft RFcr RFd RFid SG350 4350 1.61 I. /0 1.05 l.50/1.13 1.50 1.50 LTDS 2339 uncertainties: connection: Serviceability: l.50/1.13 l.50/1.13 1.00 /NA FS Tai Ci 1.50 1560/3348 0.90 Cds 0.90 Analysis.Wall No. 3A max 3.67 feet /tigl, 17 degree slope surcharge Case: Case 1 U11it Type: Standard 21.5" I 120.00 pcf Leveling Pad: Crushed Stone Wall Ht: 3.67 ft BackSlope: I 7. 00 deg. slope, Wall Batter: 4. 40 deg. embedment: 1. 00 ft 10.00 ft long Surcharge: LL: 0 psf uniform surchmge load Width: 100.00ft DL: 0 psf unifomt surcluuge load Width: 100.00ft Results: Sliding Overturuiug: Beal'ing ~ Bending Facto,~ of Safety: 4.3512.32 13.2216.34 25.83/22.54 32.6616.58 12.17 IJ.61 Calculated Bearing Pressure: 4941494/536 psf Eccentricity at base: 0.00 ft/0.19 ft Reinforcing: (ft & lbs/ft) Cale. Allow Ten Pk Conn Serv Conn Height Length Tension Reinf. Tyne Tai Tel Tse 200 5.5 2461572 SG350 1560/3348 ok 1160/154 7 ok 1272/N/A ok Reinforcing Quantities (no waste included): S0350 0.61 sylft NOTE. THESE CALCULATIONS ARE FOR PRELIMINARY DESIGN ONLY AND SHOULD NOT BE USED FOR CONSTRUCT/ON WITHOUT REVIEW BY A QUAllFJED ENGINEER Date 8/7/2008 Pullout FS 4.0811.40 ok Pagel ij ~STONE ~ ~R'rrAININGWALLSYSTEMS RETAINING WALL DESIGN Layer 2 I Version 3.5.1 Build 124 SEISMIC DESIGN, Div!, Chap 5 Project: Rosemonte East Renton Project No: KE040766B Date: 8/7/2008 Designer: SGB Case: Case I Design Method: AASHT0-96 (modified soi/ inte1face) Design Parameters Soil Parameters: Reinforced Fill Retained Zone Foundation Soil Reinforced Fill Type: A. 32 36 32 Silts & sands ..£_ 0 0 0 Unit Fill: O·ushed Stone, 1 inch minus .LI!£f 120 135 120 Peak Acceleration= 0.2/ g Vertical Acceleration= 0.00 g Factors ofSafety (::,eismic are 75% of static) sliding: l.50/1.13 pullout: overturning: 2.00/1.50 shear: bearing: 2.00/1.50 bending: Reinforcing Parameters: Strata-Grid Geogrids l.50/1.13 I.SO I.SO 7ltlt RFcr RFd RFid LTDS SG350 4350 1.61 I.JO 1.05 2339 uncertainties: connection: Serviceability: 1.50/1.l 3 1.50/1.l 3 1.00 /NA FS Tai Ci 1.50 1560/3348 0.90 Cds 0.90 A11alysis:Wa// No. 3A max 3.67 feet high 17 degree slope s111·c/,arge Case: Case 1 Unit Type: Standard 21.5" I I 20.00 pcf Wall Batter: 4.40 deg. Leveling Pad: Crnshed Stone Wall Ht: 3.67 ft embedment: 1.00ft BackS/ope: 17.00 deg. slope, I 0. 00 ftlong Surcharge: LL: 0 psf uniform surcharge Load Width: 100.00ft DL: 0 psf uniform surcharge load Width: 100.00ft Results: Slfrlim! Ovel'IHr11iug: Bearing @!f.!!! Be11diug Faclurs ufSafety: 4.3512.32 13.2216. 34 25.83122.54 26.9716.58 12.17 /1.61 Calculated Bearing Pressure: 4941494/536 psf Eccentricity at base: 0.00 ft/0.19 ft Reinforcing: (ft & lbs/ft) Cale. Allow Ten Pk Conn Serv Conn Height Length Tension Relnf. Tyge Tai Tel Tse 2.00 5.5 100/246 SG350 1560/3 348 ok //6011547 ok 1272/ NIA ok 067 5.5 1461326 SG350 1560/3348 ok 1230//640ok 13221 NIA ok Reinforcing Qua11tities (110 waste included): SG350 1.22 sylft NOTE: THESE CALCULATIONS ARE FOR PRELJMINARY DESIGN ONLY AND SHOULD NOT BE USED FOR CONSTRUCT/ON WITHOUT REVIEW BY A QUALIFIED ENGINEER Date sm2oos Pullout FS > /0/3.27 ok >/0/4.37 ok P11ge I ~~STONE ~ ~R'gAININGWALLSYSTEMS RETAINING WALL DESIGN Version 3.5.1 Build 124 SEISMIC DESIGN, Div 1, Chap 5 Layer 3 2i I Project: Rosemonte East Renton Project No: KE040766B Case: Case 2 Design Method: AASHT0-96 (modified soil bzte,face) Design Parameters Soil Parameters: Reinforced Fill Retained Zone Foundation Soil Reinforced Fill Type: _.m_ 32 36 32 Silts & sa11ds £_ 0 0 0 j'__J1£f 120 135 120 Date: 817/2008 Designer: SOB L • S iOfl Unit Fill: Crushed Stone, I inch minus I • .. 1 Peak Acceleration= 0.21 g Vertical Acceleration= 0.00 g Factors of Safety (seismic are 75% of static) sliding: 1.50/l.l 3 pullout: overturning: 2.00/1.SO shear: bearing: 2.00/1.SO bending: Reinforcing Parameters: Strata-Grid Geogrids l.50/1.13 1.50 1.50 SGJ50 Tuft 4350 RFcr 1.61 RFd I.JO RFid LTDS 1.05 2339 A11alysis:Wall No. 3A 5.67' with 17 degree slope su,-cl,a,·ge Unit Type: Standard 21.5" 1120.00 pcf leveling Pad: Crushed Stone Wall Ht: 5.67 ft BackS/ope: 17. 00 deg. slope, uncertainties: connection: Serviceability: l.50/l.l 3 l.50/1.13 1.00 /NA FS Tai Ci 1.50 1560/3348 0.90 Case: Case 2 Cds 0.90 Wall Batter: 4.40 deg. embedment: I .00 fl I 0. 00 ft long Surcharge: LL: 0 psf uniform surcharge load Width: 100.00ft DL: 0 plf uniform surcharge Load Width: 100.00ft Res11lts: Slitliug Ovel'fllnti11g FactorsoJSafety: 3.1811.53 6.84/2.72 Calculated Bearing Pressure: 7671767/1053 psf Eccentricity at base: 0. 14 ft/0.82 ft Reinforcing: (fl & lbs/fl) Height 4.00 2.67 1.33 Length 5.5 5.5 5.5 Cale. Tension 1671390 4271808 Reinf. Type SG350 SG350 SG350 Reinforcing Quantities (1w waste included): SG350 1.83 sy(ft Beat'i11g 15.98/9.30 Allow Ten Tai I 560/3348 ok 1560/3348 1560/3348 ok Shear 16.0217.47 Pk Conn Tel 1/6011547 ok 2530/3373 ok Be11di11g 12.0211.87 Serv Conn Tse 12721 NIA ok 2693/NIA ok NOTE: THESE CALCULA710NS ARE FOR PRELIMINARY DESIGN ONLY AND SHOULD NOT BE USED FOR CONSTRUCTION WITHOUT REVIEW BY A QUALIFIED ENGINEER Date sn12oos Pullout FS 4.1811.43 ok NIA 5.0912.15 ok Page I ~~STONE ~ ~iElAINING WALL SYSTEMS RETAINING WALL DESIGN Version3.5.l Build 124 SEISMIC DESIGN, Div!, Chap 5 Layer 2 I Project: Rosemonte East Renton Project No: KE040766B Case: Case 2 Design Method: AASHT0-96 (modified soil i11te1face) Design Parameters Soll Parameters: Reinforced Fill Retained Zone Foundation Soil Reinforced Fill Type: .A. 32 36 32 Silts & sands .£.. 0 a a ..Ll!£f /20 /35 120 Date: 8/712008 Designer: SGB Unit Fill: Crushed Stone, 1 inch minus Peak Acceleration= 0.21 g Vertical Acceleration= 0.00 g Factors of Safety (seismic are 75% ofstatic) sliding: l.50/1.13 pullout: overturning: 2.00/1.50 shear: bearing: 2.00/1.50 bending: Reinforcing Parameters: Strata-Grid Geogl'ids Tu/t RFcr RFd RFid SG350 4350 1.61 /.JO 1.05 A11alysis.Wal/ No. 3B 5.67' with 110 surc/1arge l.50/1.13 1.50 1.50 LTDS 2339 Unit Type.· Standard 21.5" 1120.00 pcf leveling Pad: Crushed Stone Wall Ht: 5.67 ft level Backfill Offset, I 0. 00 uncertainties: connection: Serviceability: l.50/1.13 l.50/1.13 1.00 /NA FS Tai Ci 1.50 /560/3348 0.90 Cds 0.90 Case: Case 2 Wall Batter: 4. 40 deg. embedment: 1.00 ft Surcharge: LL: 0 psf u/liform surcharge load Width: /00.00ft DL: 0 psf unifinw surcharge load Width: I 00. 00 ft Results: Sliding Ovel't11n1iug Factors of Safety: 5.3112.25 15.11/4.81 Calculated Bearing Pressure: 682 I 6821804 p,f Eccentricity at base: 0.11 ft/0.59 ft Reinforcing: ( ft & lbs/ft) Height 4.00 2.00 Length 6.5 6.5 Cale. Tension 1191357 4/81737 Rcinf. Type SG350 SG350 Reinforcing Quantities (no waste included): SG350 1.44 sy/ft Beal'i11g 20.76115.46 Allow Ten Tai 1560/3348 ok 1560/3348 ok Shear 16.96/8.7/ Pk Conn Tel 1/60/1547 ok /265/1686 ok Be11di11g 13.2812.46 Serv Conn Tse 12721 NIA ok 1346/ NIA ok NOTE-THESE CALCULATIONS ARE FOR PRELIMINARY DESIGN ONLY AND SHOULD NOT BE USED FOR CONSTRUCTION WITHOUT REVIEW BY A QUALIFIED ENGINEER Date 8/712008 ! Pullout FS 5.2911.41 ok 4.4512.02 ok Page I i~STONE ~ v~AININGWALLSYSTEMS RETAINING WALL DESIGN Version3.5.l Build 124 SEISMIC DESIGN, Div!, Chap 5 Project: Rosemonte East Renton Project No: KE040766B Date: 8/7/2008 Designer: SGB ./ Layer 3 2i I Case: Case 3 Design Method: AASHT0,96 (modified soil i11te1f'ace) Design Parameters Soil Parameters: Reinforced Fill Retained Zone Foundation Soil Reinforced Fill Type: _m_ 32 36 32 Silts & sands ..£. 0 0 0 Unit Fill: Crushed Stone, 1 inch minus .Ll!£f 120 135 120 Peak Acceleration= 0.2 I g Vertical Acceleration= 0.00 g Factors of Safety (seismic are 75% of static) sliding: 1.50/ l.13 pullout: overturning: 2.00/1.50 shear: bearing: 2.00/1.50 bending: Reinforcing Parameters: Strata-Grid Geogrids l.50/1.13 1.50 1.50 Tuft RFcr RFd RFid LTDS SG350 4350 1.61 I.JO 1.05 2339 Aualysis:Wall No. 3B 7' wall 2:1 slope surcltal'gefor 10' Unit Type: Standard 21.5" I /20.00 pcf Leveling Pad· Crushed Stone Wall Ht.· 7.00 ft BackS/ope: 26. 00 deg. slope, unce1tainties: connection: Serviceability: l.50/1.13 l.50/1.13 1.00 /NA FS Ta/ Ci /.50 1560/3348 0.90 Cds 0.90 Case: Case 3 Wall Batter: 4.40 deg. embedme11t: 0.50ft 10.00 ft long Surcharge: LL: 0 p!if uniform surcharge Load Width: 100.00ft DL: 0 psf uniform surcharge Load Width: /00.00ft Results: Sliding Overtuming Factors of Safety: 2.3311.31 4.4312.21 Calculated Bearing Pressure: 1077 I I 077/1542 psf Eccentricity at base: 0.37 1\/1.21 ft Reinforcing: (ft & lbs/ft) Cale. Height Length Tension Reinf. T:y!;!e 5.33 6.5 305/6/3 SG350 3.33 6.5 SG350 1.33 6.5 799/ 1379 SG350 Reinforcing Quantities (no waste included): SG350 2.17 sy/ft Bem·ilig 10.99/5.70 Allow Ten Tai 1560/3348 ok /560/3348 /560/3348ok Shear 6.7014.72 Pk Conn Tel 1160/1547 ok 2634/3511 ok Bending 9.69 /1.86 Serv Conn Tse 1272/NIA ok 27671 NIA ok NOTE: THESE CALCULATIONS ARE FOR PRELIMINARY DESIGN ONLY AND SHOULD NOT BE USED FOR CONSTRUCT/ON WITHOUT REVIEW BY A QUALIFIED ENGINEER Date 817/2008 Pullout FS 3.85//, 53 ok NIA 5.0412.34 ok Page 1 il~51~0NE ~ ~R,EIAININGWALLSTSTEMS RETAINING WALL DESIGN Version 3.5.1 Build 124 SEISMIC DESIGN, Div!, Chap 5 Project: Rosemonte East Renton Project No: KE040766B Case: Case 4 Design Method: AASHT0-96 (modified soil inte1face) Design Parameters Soil Parameters: ..l Retained Zone 36 0 Foundation Soil 32 0 Unit Fill: Crushed Stone, I inch minus .1....filf 135 120 Date: 8/7/2008 Designer: SGB Peak Acceleration= 0.21 g Verlical Acceleration= 0.00 g Factors of Safety (seismic are 75% of static) sliding: I.50/1.13 pullout: overturning: 1.50/0.00 shear: bearing: 2.00/1.50 bending: I.50/1.13 I.SO I.SO AnalysisWall No. 3B 2.5' wall 2:1 slope surcharge for 10' Unit Type: Standard 21.5" / 120.00 pcf Leveling Pad: Crushed Stone Wall Ht: 2.50 ft BackSlope: Surcharge: 26.00 deg. slope, LL: 0 psf uniform surcharge Load Width: l 00.00 ft Results: Sliding Overturning Factors of Safety: 3.79/1.25 S.37/1.37 Calculated Bearing Pressure: 301 I 301/600 psf Eccentricity at base: 0.01 ft/0.60 ft uncertainties: connection: Serviceability: I.50/1.13 l.50/1.13 1.00 /NA Case: Case 4 Wall Batter: 4.40 deg. embedment: 0.50 ft 10.00 ft long D L: 0 psf uniform surcharge Load Width: I 00.00 ft Bearing ·22.90/7.90 NIA Bending NIA NOTE: THESE CALCULA110NS ARE FOR PREl/MlNARY DESIGN ONLY AND SHOULD NOT BE USED FOR CONSTRUCTION WITHOUT REVIEW BY A QUAl/FIED ENGINEER Date sn12oos Page I l~STONE ~ ~~AININGWAllSYSTEMS RETAINING WALL DESIGN Layer 3 2i I Version 3.5.1 Build 124 SEISMIC DESIGN, Divl, Chap 5 Project: Rosemonte East Renton Project No: KE040766B Date: 8/7/2008 Designer: SGB Case: Case I Design Method: AASHT0-96 (modified soil inte1face) Design Parameters Soil Parameters: Reinforced Fill Retained Zone Foundation Soil Reinforced Fill Type: .i. 32 36 32 Silts & sands ..£. 0 0 0 Unit Fill: Crushed Stone, I inch minus __t__J!ff 120 135 120 Peak Acceleration= 0.2 I g Vertical Acceleration= 0.00 g Factors a/Safety (seismic are 75% of static) sliding: 1.5011.13 pullout: overturning: 2.00/1.50 shear: bearing: 2.0011.50 bending: Reinforcing Parameters: Strata-Grid Geugrids Tult RFcr RFd RFid SG350 4350 1.61 I.JO 1.05 1.5011.13 1.50 I.SO LTDS 2339 Aualysis.fYa/l No. 3C max 6.5 feet high ,w surcharge Unit Type: Standard 21.5" I 120.00 pcf Leveling Pad: Crushed Stone Wall Ht.· 6.50 ft Level Backfill Offset: I 0. 00 unce11ainties: connection: Serviceability: 1.5011.13 1.5011.13 1.00 /NA FS Tai Ci 1.50 1560/3348 0.90 Cds 0.90 Case: Case I Wall Batter: 4.40 deg. embedment: 2.00 ft _____ ... _____ _ ... -. --------- L • 7 OOfl .. 1 Surcharge: LL: 0 psfuniform surcharge Load Width: 100.00ft DL: 0 psf uniform surcharge Load Width .. /00.00 ft Results: Sliding Ovel'l11rni11g Factors of Safety: 4.98/2./ I 13.3314.24 Calculated Bearing Pressure.: 785 I 785195 I psf Eccentricity at base: 0.15 ft/0. 73 ft Reinforcing: (ft & lbs/ft) Height 4.67 2.67 0.67 Length 7.0 7.0 7.0 Cale. Tension 246 I 503 460/ 882 Reinf. Type SG350 SG350 SG350 Reinforcing Quantities (no waste i11cluded): SG350 2.33 sy/ft Bearing 22.55//6.41 Allow Ten Tai J 560/3348 ok I 560/3348 1560/3348 ok Shear 7.7914.49 Pk Conn Tel J/69/1559ok 2651135 35 ok Bending /1.09/2.16 Serv Conn Tse 1278/ NIA ok 27791 NIA ok NOTE.-THESE CALCULATIONS ARE FOR PRELIMINARY DESIGN ONLY AND SHOULD NOT BE USED FOR CONSTRUCT/ON WITHOUT REVIEW BY A QUALIFIED ENGINEER Date an12oos Pullout FS 3.00ll.17ok NIA 8.3613.49 ok ;~STONE ~ ~REIAINING WALL SYSTEMS Project: Rosemonte East Renton Project No: KE0407668 Case: Case 2 RETAINING WALL DESIGN Version 3.5.1 Build 124 SEISMIC DESIGN, Div!, Chap 5 Design Method: AASHT0-96 (modified soil inte,face) Date: 8/7/2008 Designer: SGB Design Parameters Soil Parameters: Reinforced Fill Retained Zone Foundation Soil Reinforced Fill Type: j_ 32 36 32 .£. 0 0 0 L..l!£f 120 135 120 ----r----------__ .•. -.--.· __ ]: :~J -/ ------------J 1 Silts & sands Unit Fill: Crushed Stone, I inch minus Peak Acceleration= 0.21 g Verticnl Acceleration= 0.00 g Factors of Safety (seismic are 7 5% of static) sliding: l.50/1.13 pullout: overturning: 2.00/1.50 shear: bearing: 2.00/1.50 bending: Reinforcing Parameters: Strata-Grid Geogrids Tutt RFcr RFd RFid SG350 4350 /.61 I.JO 1.05 A11alysis:Wal/ No. JC 4.5' with 110 s11rchal'ge l.50/1.13 1.50 1.50 LTDS 2339 Unit Type: Standard 21.5" I /20.00 pcf Leveling Pad: Crushed Stone Wall Ht: 4.50 ft Level Backfill Offset: 10.00 uncertainties: connection: Serviceability: l.50/1.13 1.50/1.!3 1.00 /NA FS Tai Ci 1.50 1560/3348 0.90 Cds 0.90 Case: Case 2 Wall Batter: 4.40 deg. embedment: 0.50 ft L" 7 00ft .. 1 Surcharge: LL: 0 psfuniform surcharge Load Width: /00.00 ft DL: 0 psf uniform surcharge load Width: 100.00ft Results: Sliding Ovel'turnillg Facta,~ a/Safety: 7.2813.09 27.84/8.86 Calculated Bearing Pressure: 533 I 5331579 psf Eccentricity at base: 0.04 ft/0.32 ft Reinforcing: (ft & lbs/ft) Cale. Layer Height Length Tension 2 3.33 7.0 56/241 2.00 7.0 282/500 Reinf. Type SG350 SG350 Reinforcing Quantities (no waste included): SG350 1.56 sy!ft Bearing 26.12122.30 Allow Ten Tai 1560/3348 ok 1560/3348 ok Sltear 35.58 /15.39 Pk Conn Tel 1134!/5/2ok 1204/ 1605 ok Bending 26.66 /3.98 Serv Conn Tse 1253/ NIA ak /303/ NIA ok NOTE: THESE CALCULATIONS ARE FOR PRELIMINARY DESIGN ONLY AND SHOULD NOT BE USED FOR CONSTRUCTION WITHOUT REVIEW BY A QUALIFIED ENGINEER Date 8/7/2008 Pullout FS >/0//.89 ok 5.0812.30 ok Page 1 ~~STONE ~ ~R'aAJMNGWALLSYSTEMS RETAINING WALL DESIGN Version 3.5.1 Build 124 SEISMIC DESIGN, Div!, Chap 5 Project: Rosemonte East Renton Project No: KE040766B Case: Case 3 Design Method: AASHT0-96 (modified soil inte1face) Design Parameters Soil Parameters: A. .£. Retained Zone 36 0 Fou11datio11 Soil 32 0 Unit Fill: Crushed Stone, 1 inch minus 1..J!£f 135 120 Date: 817/2008 Designer: SGB Peak Acceleration= 0.21 g Vertical Acceleration= 0.00 g Factors ofSafety (seismic are 75% of static) sliding: 1.5011.13 pullout: overturning: 1.5010.00 shear: bearing: 2.0011.50 bending: AnalysisWall No. 3C 2.5' wall no surcharge 1.5011.13 1.50 1.50 Unit Type: Standard 21.5" 1120.00 pcf Leveling Pad: Crushed Stone Wall Ht: 2.50 ft Level Backfill Offset: 10.00 Surcharge: LL: 0 psf unifo1m surcharge Load Width: I 00.00 ft Results: Sliding Overturning Factors of Safety: 4.6211.65 6.5511. 73 Calculated Bearing Pressure: 311 I 3111451 psf Eccentricity at base: 0.06 fV0.48 ft uncertainties: connection: Serviceability: 1.5011.13 1.5011.13 1.00 /NA Case: Case 3 Wall Batter: 4.40 deg. embedrnent: 0.50 ft DL: 0 psfuniform surcharge Load Width: 100.00 ft Bearing 21.63/11.52 Shear NIA Bending NIA NOTE: THESE CALCULATIONS ARE FOR PRELIMINARY DESIGN ONLY AND SHOULD NOT BE USED FOR CONSTRUCTION WITHOUT REVIEW BY A QUAl/FIED ENGINEER Date 8/7n008 Page I RETAINING WALL DESIGN Version 3.5.1 Build 124 SEISMIC DESIGN, Div!, Chap 5 Project: Rosemonte -East Renton Project No: KE040766B Date: 817/2008 Designer: SGB Case: Case I Design Method: AASHT0-96 (modified soil inte1face) Design Parameters Soil Parameters: .!. Retained Zone 36 0 Foundation Soil 32 0 Unit Fill: Crushed Stone, I inch minus -l'.....J!£f /35 120 Peak Acceleration= 0.21 g Vertical Acceleration= 0. 00 g Factors of Safety (seismic are 75% of static) sliding: 1.5011.13 pullout: overturning: 1.5010.00 shear: bearing: 2.0011.50 bending: 1.5011. 13 1.50 1.50 uncertainties: connection: Serviceability: 1.5011.13 1.5011.13 1.00 /NA AnalysisWall No. 4 2.5' with traffic surcharge 5' behind wall Case: Case l Unit Type: Standard 21.5" 1120.00 pcf Leveling Pad: Crnshed Stone Wall Ht: 2.50 ft Level Backfill Offset: 3.00 Surcharge: LL: 150 psfunifmm surcharge Load Width: 100.00 ft Results: Sliding Overturning Factors of Safety: 4.6211.65 6.5511.73 Calculated Bearing Pressure: 311 I 311145 / psf Eccentricity at base: 0.06 ft/0.48 ft Wall Batter: 4.40 deg. embedment: 0.50 ft DL: 100 psfuniformsurcharge Load Width: 100.00 ft Bearing 21.63/11.52 ' Shear NIA Bending NIA NOTE: THESE CALCULATIONS ARE FOR PRELIMINARY DESIGN ONLY AND SHOULD NOT BE USED FOR CONSTRUCT/ON WITHOUT REVIEW BY A QUALIFIED ENGINEER Date Bn/2008 Page I l~STONE 1,,$\, v~AJNING WAllSYSTEMS RETAINING WALL DESIGN Version 3.5.l Build 124 SEISMIC DESIGN, Div!, Chap 5 Layer 3 2 Project: Rosemonte -East Renton Project No: KE040766B Case: Case 2 Design Method: AASHT0-96 (modified soil i11te1face) Design Parameters Soil Parameters: Reinforced Fill Retained Zo11e Foundation Soil Reinforced Fill Type: j_ 32 36 32 Silts & sa11ds .£. 0 0 0 Unit Fill: Crushed Stone, 1 inch minus ..LI!.£! 120 135 120 Date: 8/712008 Designer: SOB L•650fi Peak Acceleration= 0.21 g Vertical Acceleration= 0.00 g Factors of Safety (seismic are 75% of static) sliding: 1.50/1.l 3 pullout: overturning: 2.00/1.50 shear: bearing: 2.00/1.50 bending: Reinforcing Parameters: Strata-Grid Geogrids I.50/1.13 1.50 1.50 Tult RFcr RFd RFid LIDS SG350 4350 1.6/ I.JO 1.05 2339 W1certainties: connection: Serviceability: l.50/1.13 1.50/l.13 1.00 /NA FS Tai Ci 1.50 /560/3348 0.90 Cds 0.90 A11alysis:Wall No. 4 5.67' witi, tmffic surcharge 5' behilld wall Case: Case 2 Results: U11it Type: Sta11dard 21.5'' 1120.00 pcf Leveling Pad: Crushed Stone Wall Ht: 5.67 ft level Backfill Offset: 3.00 Surcharge: LL: I 50 psf zmiform surcharge load Width: 100.00 ft Slitliug Overt11mi11g Bearing Wall Batter: 4.40 deg. embedment: 0.50 ft DL: I 00 psf w1ifvrm surcharge Load Width: 100.00ft Shear Bending •I Facto,~ of Safety: 3.3412.11 8.1714.57 17.54113.57 12.6416.84 16.2814.83 Calculated Bearing Pressure: 7381733/824 psf Eccentricity at base: 0.06 ft/0.55 ft Reinforcing: (fl & lbs/ft) Cale. Allow Ten Pk Conn Serv Conn Height Length Tension Reinf. Tyge Tai Tel Tse 4.67 6.5 671201 SC350 1560/3348 ok 1126/1501 ok 12471 NIA ok 2.67 6.5 2011386 SC350 1560/3348 ok /230/1640 ok /3221 NIA ok 0.67 6.5 267/491 SC350 1560/3348 ok /334//779ok 13961 NIA ok Reinforcing Quantities (no waste included): SC350 2.17 sylft NOTE: THESE CALCULATIONS ARE FOR PRELIMINARY DESIGN ONLY AND SHOULD NOT BE USED FOR CONSTRUCTION WITHOUT REVIEW BY A QUALIFIED ENGINEER Date 8/7/2008 Pullout FS 5.01//.34 ok 6.9412.88 ok >/014.83 ok Q~STONE ~~ ~Rr!A1NIN8WALLSY8TEMS RETAINING WALL DESIGN Version 3.5.1 Build 124 SEISMIC DESIGN, Div!, Chap 5 ' Layer 2 Project: Rosemonte -East Renton Project No: K.E040766B Case: Case I Design Method: AASHT0-96 (modified soil inte1face) Design Parameters Soil Parameters: Reinforced Fill Retained Zone Foundation Soil Reinforced Fill Type: j_ 32 36 32 Silts & sands .£. 0 0 0 ..i'....l!il 120 135 120 Date: 8/712008 Designer: SGB Unit Fill: Crushed Stone, I inch minus Peak Acceleration= 0.2 I g Vertical Acceleration= 0.00 g Factors of Safety (seismic are 75% of static) sliding: l.50/1.13 pullout: overturning: 2.00/1.50 shear: bearing: 2.00/1.50 bending: Reinforcing Parameters: S~·ata-Grid Geogrids Tuft RFcr RFd RFid SG350 4350 1.61 I.JO 1.05 l.50/1.13 I.SO 1.50 LTDS 2339 A11alysisWall No. IA 5' wit!, 1:1 slope above for Bfeet Unit Type: Standard 2/.5" I 120.00 pcf leveling Pad: Crushed Stone Wall Ht: 5.00 ft BackS/ope: 26.00 deg. slope, uncertainties: connection: Serviceability: l.50/1.13 I.50/1.13 1.00/NA FS Tai Ci 1.50 1560/3348 0.90 Cds 0.90 Case: Case 1 Wall Baller: 4.40 deg. embedment: 1.00 ft 8.00 fl/011g Surcharge: LL: 0 psfimiform surcharge Load Width: 100.00ft DL: 0 psf uniform surcharge Load Width: 100.00ft Results: Slidir,g 0Yert11r11illg Facto,~ of Safety: 2.5411.48 5.31/2.78 Calculated Bearing Pressure: 729 I 729/940 psf Eccentricity at base: 0.16 ft/0.66 ft Reinforcing: (ft & lbs/ft) Height 3.33 1.33 Length 5.0 5.0 Cale. Tension 160/366 397 I 725 Relnf. Type SG350 SG350 Reinforcing Quantities (110 waste included/' SG350 I.II sy/ft Bearing 15.441/0.07 Allow Ten Tai 1560/3348 ok I 560/3348 ok Shear 12.75 /6.80 Pk Conn Tel 1160/1547 ok 1265/1686 ok Be11dilig 9.91 /1.85 Serv Conn Tse 1272/ NIA ok /3461 NIA ok ~,, ~, ' NOTE: THESE CALCULATIONS ARE FOR PRELIMINARY DESIGN ONLY AND SHOULD NOT BE USED FOR CONSTRUCTION WITHOUT REVIEW BY A QUALIFIED ENGINEER ,. l < • ~1,@lj~Wrn ill) ~. AUG 4 21nn11 1';; '' •11:tc. qq~s. : Date Bn/2008 ~· • ~ Pullout FS 4.57/1.60 ok 4.3711.92 ok Page I \l~STONE ~ ..,,Rm!NINBWAUSYST£MS RETAINING WALL DESIGN Version 3.5.1 Build 124 SEISMIC DESIGN, Div!, Chap 5 Layer 2 I Project: Rosemonte -East Renton Project No: KE040766B Case: Case I Deslgo Method: AASHT0-96 (modified soil i11te1face) Design Parameters Soil Parameters: Reinforced Fill Retained Zone Foundation Soil Reloforced Fill Type: .i. 32 36 32 Silts & sands ..£. 0 0 0 1-.1!£! 120 135 /20 Date: 8/7/2008 Deslgoer: SGB ---.r----- 1 i Unit Fill: Crushed Stone, 1 inch minus " I Peak Acceleration= 0.2 I g Vertical Acceleration= 0.00 g Factors of Safety (seismic are 75% of static) sliding: l.50/1.13 pullout: overturning: 2.00/1.50 shear: bearing: 2.00/1.50 bending: Reloforclng Parameters: Sa·ata-Grid Geogrids Tult RFcr RFd RFid SG350 4350 1.61 I.JO I.OJ A11alysisWall No. JB 5.67' with 110 surcharge l.50/1.13 1.50 1.50 LTDS 2339 U11it Type: Sta11dard 21.5" I 120.00 pcf Leveling Pad: Crushed Stone Wall Ht: 5. 67 ft Level Backfill Offset: 0. 00 W1Certainties: connection: Serviceability: l.50/1.13 1.50/1.l 3 1.00 /NA FS Tai Ci 1.50 I 560/3348 0.90 Cds 0.90 Case: Case 1 Wall Batter: 4.40 deg. embedment: 1.00ft Surcharge: LL: 0 psf uniform surcharge Load Width: /00.00 ft DL: 0 psf uniform surcharge Load Width: 100.00ft Res11lts: Sliding Overtumi,rg Factors of Safety: 4.8912.07 I 2.87/4.09 Calculated Bearing Pressure: 686 I 6861838 psf Eccentricity at base: 0.13 ft/0.65 ft Reinforcing: (ft & lbs/ft) Height 4.00 2.00 Length 6.0 6.0 Cale. Tension J/91350 4/81745 Rein{. Type SG350 SG350 Reinforcing Quantities (no waste included): SG350 1.33 sy/ft Beari11g /9.20/13.49 Allow Ten Tai I 560/3348 ok /560/3348 ok Shear /6.95 /8.69 Pk Conn Tei JJ 60/1547 ok /265/1686 ok Be11di11g 13.2812.46 Serv Conn Tse 1272/ NIA ok 1346/N/A ok NOTE: THESE CALCULATIONS ARE FOR PRELIMINARY DESIGN ONLY AND SHOULD NOT BE USED FOR CONSTRUCTION WITHOUT REVIEW BY A QUALIFIED ENGINEER Date 8/7/2008 ' . s ' ! Pullout FS 4.35//./8 ok 3.8511.73 ok Pagel \4 ~STONE ~~ "itf RE!lllNING WALL SYSTEMS RETAINING WALL DESIGN Layer 4 3 2 I Version3.5.l Build 124 SEISMIC DESIGN, Div!, Chap 5 Project: Rosemonte -East Renton Project No: KE040766B Date: 817/2008 Designer: SGB Case: Case I Design Method: AASHT0-96 (modified soil inte,face) Design Parameters Soil Parameters: Reinforced Fill Retained Zone j_ 32 36 Foundation Soil 32 Reinforced Fill Type: Silts & sands .£. a a 0 Unit Fill: Crushed Stone, I inch minus .L.Jill /20 135 120 Peak Acceleration= 0.21 g Vertical Acceleration= 0.00 g Factors of Safety (seismic are 75% of static) sliding: l.50/1.13 pullout: overturning: 2.00/1.50 shear: bearing: 2.00/l.50 bending: Reinfordng Parameters: Su·ata-Grid Geogrids Tult RFcr RFd RFid SG350 4350 1.61 I.JO 1.05 1.50/1.l 3 1.50 1.50 LTDS 2339 Analysis.Wall No. 212.33' wit!, traffic surcharge Unit Type: Standard 2/.5" I 120.00 pcf Leveling Pad: Crnsl,ed Stone Wall Ht: 12.33 ft Level Backfill Offset: 5.00 uncertainties: connection: Serviceability: l.50/1.13 l.50/1.13 1.00 /NA FS Tai Ci 1.50 /56013348 0.90 Cds 0.90 Case: Case 1 Wall Batter: 4.40 deg. embedment: 3.00 ft Surcharge: LL: 150 psf uniform surcharge Load Width: 100.00ft DL: JOO psfuniform surcharge Load Width: I 00. 00 ft Results: Sliding Overt11mi11g Factors of Safety: 2. 7611.45 4.8612.12 Calculated Bearing Pressure: /691 I /697/2549 psf Eccentricity at base: 0.60 ft/2.08 ft Reinforcing: (ft & lbs/ft) Cale. Height Length Tension 10.67 9.5 /50 I 414 8.00 9.5 386 I 778 5.33 9.5 624 I 1144 2.67 9.5 /4/9/2021 Relnf. Ty~e SG350 SG350 SG350 SG350 Reinforcing Quantities (no waste included): SG350 4.22 syljl Beari11g 13.83/7.07 Allow Ten Tai I 560/3348 ok 1560/3348 ok /560/3348ok 1560/3348 ok Shear 5.3913.48 Pk Conn Tel /160/1547 ok 1299/1732 ok /438/1918 ok /57712/03 ok Be11di11g 8.45 12.47 Serv Conn Tse 1272/ NIA ok 1371/N/Aok 14701 NIA ok 1569/ NIA ok NOTE: THESE CALCULATIONS ARE FOR PRELIMINARY DESIGN ONLY AND SHOULD NOT BE USED FOR CONSTRUCTION WITHOUT REVIEW BY A QUALIFIED ENGINEER Date Bn/2008 Pullout FS 5.84/1.70 ok 6.98/2. 77 ok 8.69/3.79 ok 6. 38/3.58 ok Page I "41 TONE ~ C:7.~··· ~ • IIEIAOONO WALL SfflEMS RETAINING WALL DESIGN Version 3.5.1 Build 124 SEISMIC DESIGN, Div!, Chap 5 Layer I Project: Rosemonte East Renton Project No: KE040766B Case: Case I . Design Method: AASHT0-96 (modified soil interface) Design Parameters SoU Parameters: j_ .£. :t.._ng Date: 817/2008 Designer: SGB .· / Reinforced Fill Retained Zone 32 0 /20 --:--------- Foundation Soil Reinforced Fill Type: 36 32 Silts & sands 0 0 Unit Fill: Crushed Stone, I inch minus 135 /20 / / L• s son Peak Acceleration= 0.21 g Vertical Acceleration= 0.00 g Factors of Safety (seismic are 75% of static) sliding: l.50/1.13 pullout: overturning: 2.00/1.50 shear: bearing: 2.00/1.50 bending: Reinforcing Parameters: Sn·ata-Grid Geogrids Tult RFcr RFd RFid SG350 4350 I.61 I.JO 1.05 l.50/1.13 1.50 1.50 LTDS 2339 uncertainties: coIU1ection: Serviceability: l.50/1.13 1.50/1.!3 1.00 /NA FS Tai Ci 1.50 /560/3348 0.90 Cds 0.90 Analysis.Wall No. 3A max 3.67 feet ltiglt 17 degree slope surcltarge Case: Case I Results: Unit Type: Standard 21.5" I 120.00 pcf Leveling Pad: Crushed Stone Wall Ht: 3.67 ft BackS/ope.· I 7. 00 deg. slope, Surcharge: LL: 0 psf uniform surcharge load Width: 100.00ft Sl/dillg Overt11nii11g Beari11g Wall Batter: 4.40 deg. embedment: 1.00ft 10.00 ft long DL: 0 psf uniform surcharge load Width: I 00. 00 ft Sltear Be11di,1g • I Factors of Safety: 4.3512.32 I 3.22/6.34 25.83/22.54 32.6616.58 12./7 //.61 Calculated Bearing Pressure: 494 I 494/536 psf Eccentricity at base: 0.00 ft/0.19 ft Reinforcing: (ft & lbs/ft) Cale. Allow Ten Pk Conn Serv Conn ~ Length Tension Rein£. Trge Tai Tel Tse 2.00 5.5 246/572 SG350 1560/3348 ok 1/60/1547 ok 1272/ NIA ok Reinforcing Quantities (no wl1ste included): SG350 0.6/ sylft NOTE: THESE CALCULATIONS ARE FOR PRELIMINARY DESIGN ONLY AND SHOULD NOT BE USED FOR CONSTRUCT/ON WITHOUT REVIEW BY A QUALIFIED ENGINEER Date Sn/2008 / / Pullout FS 4.08//.40 ok Page I w]~STONE ~ ""'IIEDllllNOWAlLSTSTEMS RETAINING WALL DESIGN Layer 2 Version 3.5.1 Build 124 SEISMIC DESIGN, Div!, Chap 5 Project: Rosemonte East Renton Project No: KE040766B Date: 817/2008 Designer: SGB Case: Case I Design Method: AASHT0-96 (modified soil interface) Design Parameters Soll Parameters: Reinforced Fill Retained Zone Foundation Soil Reinforced Fill Type: ..m.. 32 36 32 Silts & sands .£. 0 0 0 Unit Flll: Crushed Stone, 1 inch minus .1.._l!£f 120 135 /20 Peak Acceleration= 0.21 g Vertical Acceleration= 0.00 g Factors of Safety (seismic are 75% of static) sliding: l.50/1.13 pullout: overturning: 2.00/1.50 shear: bearing: 2.00/1.50 bending: Reinforcing Parameters: Sh·ata·Grid Geogrids Tt1/t RFcr RFd RFid SG350 4350 I.61 I.IO 1.05 l.50/1.13 1.50 1.50 LTDS 2339 uncertainties: connection: Serviceability: l.50/1.13 l.50/1.13 1.00 /NA FS Tai Qi 1.50 1560/3348 0.90 Cds 0.90 A11alysis:Wal/ No. 3A max 3.67 feet/1ig/117 degree slope s11rcllarge Case: Case I Unit Type: Standm·d 21.5" I I 20.00 pcf Leveling Pad: Crushed Stone Wall Ht: 3.67 ft BackS/ope: 17. 00 deg. slope, Wall Batter: 4.40 deg. embedment: 1.00 ft 10.00 ft long Surcharge: LL: 0 psf uniform surcharge load Width: I 00. 00 ft DL: 0 pJf uniform surcharge load Width: /00.00 ft Resulls: Sliding Overtun1i11g Bearing ~ Betidi11g Factors of Safety: 4.3512.32 13.2216.34 25.83122.54 26.9716.58 /2./7 /l.6/ Calculated Bearing Pressure: 4941494/536 psf Eccentricity at base: 0.00 ft/0.19 ft Reinforcing: (ft & lbs/ft) Cale. Allow Ten Pk Conn Serv Conn Height Length Tension Relnf, True Tai !fl Tse 2.00 5.5 /00/246 SG350 1560/3348 ok 1160//547 ok 12721 NIA ok 0.67 5.5 146/326 SG350 / 56013348 ok /230//640ok 13221 NIA ok Reinforcing Quantities (no waste included): SG350 I .22 sy/ft NOTE: THESE CALCULATIONS ARE FOR PREL/MINARY DESIGN ONLY AND SHOULD NOT BE USED FOR CONSTRUCTION WITHOUT REVIEW BY A QUAL/F/ED ENGINEER Date &n/2008 Pullout FS >1013.27 ok >/014.37 ok Page I .. ",,:.•,' vl~STONE ~ ""llflAIIIINBWALLBYSTEMS RETAINING WALL DESIGN Version 3.5.1 Build 124 SEISMIC DESIGN, Div!, Chap 5 Layer 3 2i I Project: Rosemonte East Renton Project No: KE040766B Case: Case 2 Design Method: AASHT0-96 (modified soil i11terface) Design Parameters Soil Parameters: Reinforced Fill Retained Zone Foundation Soil Reinforced Fill Type: ..t. 32 36 32 Silts & sands ..£.. 0 0 0 ..Ln£! 120 135 120 Date: 817/2008 Designer: SGB Unit Fill: Crushed Stone, I inch minus c[ Peak Acceleration= 0.21 g Vertical Acceleration= 0.00 g Factors of Safety (seismic are 75% of static) sliding: l.50/1.13 pullout: overturning: 2.00/1.50 shear: bearing: 2.00/1.50 bending: Reinforcing Parameters: Strata-Grid Geog1·ids Tuft RFcr RFd RFid SG350 4350 l.61 I.JO 1.05 l.50/1.13 1.50 1.50 LTDS 2339 A11alysisWall No. 3A 5.67' with 17 degree slope surcharge U11it Type: Standard 21.5" I /20.00 pcf Leveling Pad: Cmshed Stone Wall Ht: 5.67 Ji BackS/ope: I 7.00 deg. slope. uncertainties: c0IU1ection: Serviceability: l.50/1.13 l.50/1.13 1.00 /NA FS Tai Ci 1.50 1560/3348 0.90 Case: Case 2 Cds 0.90 Wall Batter: 4.40 deg. embedment: 1.00ft I 0. 00 Ji long S11rcharge: LL: 0 psf1111ifor111 s11rcharge Load Width: 100.00ft DL: 0 psf uniform surcharge Load Width: 100.00 ft Results: Slidi11g Ovel'tlll'lling Beari11g Shear Ber,ding · Facto,~ of Safety: 3./811.53 6.8412.72 15.9819.30 /6.0217.47 /2.0211.87 Calculated Bearing Pressure: 767 I 7671/053 psf Eccentricity at base: 0.14 ft/0.82 ft Reinforcing: (ft & lbs/ft) Cale. Allow Ten Pk Conn Serv Conn Height Length Tension Relnf. Tye• Tai Tei Tse 4.00 5.5 167 /390 SG350 I 56013348 ok 1/601/547 ok 1272/ NIA ok 2.67 5.5 SG350 I 56013348 1.33 5.5 427 I 808 SG350 I 56013348 ok 253013373 ok 2693INIA ok Reinforcing Quantities (no waste included): SG350 l.83 sy/fi NOTE: THESE CALCULATIONS ARE FOR PRELIMINARY DESIGN ONLY AND SHOULD NOT BE USED FOR CONSTRUCTION WITHOUT REVIEW BY A QUALIFIED ENGINEER Date Sn/2008 Pullout FS 4.1811.43 ok NIA 5.09/2./5 ok Page 1 Layer I RETAINING WALL DESIGN Version 3.5.1 Build 124 SEISMIC DESIGN, Div!, Chap 5 Project: Rosemonte East Renton Project No: KE040766B Date: 8/712008 Designer: SGB Case: Case I Design Method: AASHT0-96 (modified soil inte,face) Design Parameters Soll Parameters: A. Reinforced Fill 32 Retained Zone 36 Foundation Soil 32 Reinforced Fill Type: Silts & sands ..£. 0 0 0 Unit FIii: Crushed Stone, I inch minus .l.....J!S!: 120 135 120 Peak Acceleration= 0.21 g Vertical Acceleration= 0.00 g Factors of Safety (seismic are 75% of static) sliding: l.50/1.13 pullout: overturning: 2.00/1.50 shear: bearing: 2.00/1.50 bending: Reinforcing Parameters: Sn·ata-Grid Geogrids Tuft RFcr RFd RFid SG350 4350 l.61 I.JO 1.05 l.50/1.13 1.50 1.50 LTDS 2339 A11alysls:Wall No. 3B max 3.5 feet lriglr 110 s11rcharge Unit Type: Standard 21.5" I I 20.00 pc/ leveling Pad: Crushed Sto11e Wall Ht: 3.50 ft Level Backfill Offset: 10.00 Surcharge: LL: 0 psfuniform surcharge Load Width: 100.00ft Results: Sliding Overt111·11i11g Factors of Safety: 8. 7213.66 39.69/12.48 Calculated Bearing Pressure: 4 I 3 14 I 31438 psf Eccentricity at base: 0.02 ft/0.20 ft Reinforcing: (ft & lbs/ft) uncertainties; connection: Serviceability: l.50/1.13 l.50/1.13 1.00 /NA FS Tai Ci 1.50 1560/3348 0.90 Cds 0.90 Case: Case 1 Wall Batter: 4.40 deg. embedment: 1.00 ft DL: 0 psfuniform surcharge Load Width: I 00.00 ft Bearlt,g Shear Bendi11g 35.08/31.60 43.89110.94 16.3512.84 Cale. Allow Ten Pk Conn Serv Conn fu!&!il Length Tension Relnf. IYBe Tal I£! Tse [ .. 1 Pullout FS 2.00 6.5 2051492 SG350 1560/3348 ok 1152/1535 ok 1266/ NIA ok 3.71//.24 ok Reinforcing Quantities (no waste included): SG350 0. 72 sy!ft Date Bn/2008 NOTE: THESE CALCULA710NS ARE FOR PRELIMINARY DESIGN ONLY AND SHOULD NOT BE USED FOR CONSTRUCTION WITHOUT REVIEW BY A QUALIFIED ENGINEER Page I VA'! STONE ~ w7.I: ···i'i ~ . REIAININB WALL SYSTEMS RETAINING WALL DESIGN Version 35-1 Build 124 SEISMIC DESIGN, Div!, Chap 5 Layer 2 I Project: Rosemonte East Rellton Project No: KE040766B Case: Case 2 Design Method: AASHT0-96 (modified soil i11te,face) Design Parameters Soll Parameters: .i. Reinforced Fill 32 Retained Zone 36 Foundation Soil 32 Reinforced Fill Type: Silts & sands .£. 0 0 0 .L.J!tl 120 135 120 Date: 817/2008 Designer: SGB Unit Fill: Crnshed Stone, I inch minus Peak Acceleration -021 g Vertical Acceleration~ 0.00 g Facto,~ of Safety (seismz'c are 75% of static) sliding: 150/1.13 pullout: overturning: 2.00/1.50 shear: bearing: 2.00/LSO bending: Reinforcing Parameters: Sh·ata-Grid Geogrids Tult RFcr RFd RFid SG350 4350 1.61 UO 1-05 A11alysis.Wall No. 3B 5.67' with ,io surcharge l.50/1.13 1.50 LSO LTDS 2339 Unit Type.· Standard 2 JS' I I WOO pcf Leveling Pad: Crushed Stone Wall Ht: 5.67 ft level Backfill Offset: IMO uncertainties: connection: Serviceability: l.50/1.13 l.50/1.13 LOO/NA FS Tai Ci UO I 56013348 0.90 Cds 0.90 Case: Case 2 Wall Batter: 4AO deg. embedment: 1.00 ft Surcharge: LL: 0 psf uniform surcharge load Width.· 100.00ft DL: 0 psf uniform surcharge load Width· I 00. 00 ft Results: Sliding Ove,111r11ilig Factors of Safety: 5-311225 15.J /NB/ Calculated Bearing Pressure: 682 I 6821804 psf Eccentricity at base: 0.11 ft/0.59 ft Reinforcing: (ft & lbs/ft) Height 4.00 2.00 Length 6.5 6.5 Cale. Tension 1191357 4181737 Relnf. Type SG350 SG350 Reinforcing Quantities (no waste included): SG350 1.44 sylft Beari11g 20. 76115.46 Allow Ten Tai 1560/3348 ok I 560/3348 ok Shear 16.96/8.71 Pk Conn Tel 1/60/1547 ok 1265/1686 ok Be11di11g I 3.2812.46 Serv Conn Tse 12721 NIA ok 13461 NIA ok NOTE.-THESE CALCULATIONS ARE FOR PRELIMINARY DESIGN ONLY AND SHOULD NOT BE USED FOR CONSTRUCTION WITHOUT REVIEW BY A QUAl!FIED ENGINEER Dote sn12oos Pullout FS 5.2911.41 ok 4.4512.02 ok f)~STONE \J~ ~~NlNOWAlLSYSTEMS RETAINING WALL DESIGN Layer 3 2i I Version 3.5.1 Build 124 SEISMIC DESIGN, Div!, Chap 5 Project: Rosemonte East Renton Project No: KE040766B Date: 817/2008 Designer: SGB Case: Case 3 Design Method: AASHT0-96 (modified soil i11te,face) Design Parameters SoU Parameters: Reinforced Fill Re1a;ned Zone Foundation Soil Reinforced FIii Type: i 32 36 32 Silts & sands .£. 0 0 0 Unit FiU: Crushed Stone, I inch minus ..L.J!rl 120 135 120 Peak Acceleration= 0.21 g Vertical Acceleration= 0.00 g Factors of Safety (seismic are 75% of static) sliding: l.50/1.13 pullout: overturning: 2.00/1.50 shear: hearing: 2.00/1.50 bending: Reinforcing Parameters: Sn·ata-Grid Geogrids Tult RFcr RFd RFid SG350 4350 l.6/ I.JO /.05 l.50/1.13 1.50 1.50 LTDS 2339 A11alysisJJla/l No. JB 7' wall 1: 1 slope s11rc/large for 10' Unit Type: Standard 21.5" I I 20.00 pcf leveling Pad Crushed Stone Wall Ht: 7.00 ft BackS/ope: 26.00 deg. slope, uncertainties: connection: Serviceability: l.50/1.13 l.50/1.13 1.00 /NA FS Tai Ci 1.50 1560/3348 0.90 Cds 0.90 Case: Case 3 Wall Batter: 4.40 deg. embedmem: 0.50ft 10.00 ft long Si,rcharge: LL: 0 psf uniform surcharge Load Width: I 00. 00 ft DL: 0 psf uniform surcharge Load Width: 100. 00 ft Results: S1idi11g 011ertur11i11g Factors of Safety: 2.3311.31 4.4312.21 Calculated Bearing Pressure: 1077 I 10771/542 psf Eccenbicity at base: 0.37 ft/1.21 ft Reinforcing: (ft & lbs/ft) Cale. Height Length Tension Reinf. Txl!e 5.33 6.5 305/613 SG350 3.33 6.5 SG350 1.33 6.5 799/ 1379 SG350 Reinforcing Quantities (110 waste i11c/uded): SG350 2. I 7 sy/ft Beari11g 10.99/5.70 Allow Ten Tai I 56013348 ok /560/3348 1560/3348 ok Shear 6.7014.72 Pk Conn Tel 1160/1547 ok 2634/35 /1 ok Be11di11g 9.69 /1.86 ServConn Tse 12721 NIA ok 27671 NIA ok NOTE: THESE CALCULATIONS ARE FOR PRELIMINARY DESIGN ONLY AND SHOULD NOT BE USED FOR CONSTRUCTION WITHOUT REVIEW BY A QUALIFIED ENGINEER Date 817/2008 Pullout FS 3.85/1.53 ok NIA 5.0412.34 ok Page 1 ii.STONE '1~ .,.RETAININGWALLS!STEMS RETAINING WALL DESIGN Version 3.5.1 Build 124 SEISMIC DESIGN, Div!, Chap 5 Project: Rosemonte East Renton Project No: KE040766B Case: Case4 Design Method: AASHT0-96 (modified soil interface) Design Parameters Soil Parameters: ..l ..£. Retained Zone 36 0 Foundation Soil 32 0 Unit Fill: Crushed Stone, I inch minus .LJ!£f 135 120 Date: 81712008 Designer: SGB Peak Acceleration= 0.2 I g Vertical Acceleration= 0.00 g I"' 1.5011.13 1.5011.13 1.00 /NA Factors of Safety (seismic are 75% of static) sliding: 1.5011.13 pullout: overturning: 1.5010.00 shear: bearing: 2.0011.50 bending: 1.5011.13 1.50 1.50 Analysis!tVaii No, 3B 2.5' wail 2:1 slope surcharge for 10' Unit Type: Standard 21.5" I 120.00 pcf Leveling Pad: Crushed Stone Wail Ht: 2.50 ft BackSlope: 26.00 deg. slope, Surcharge: LL: 0 psfuniform swcharge Load Width: I 00.00 ft Results: Sliding Overturning Factors of Safety: 3.7911.25 5.3711.37 Calculated Bearing Pressure: 301 I 3011600 psf Eccentricity at base: O.DI ft/0.60 ft uncertainties: co1U1ection: Serviceability: Case: Case 4 Wail Batter: 4.40 deg. embedment: 0.50 ft 10.00 ft long DL: 0 psfunifonn surcharge Load Width: I 00.00 ft Bearing 22.90/7.90 Shear NIA Bending NIA NOTE: THESE CALCULATIONS ARE FOR PRELIMINARY DESIGN ONLY AND SHOULD NOT BE USED FOR CONSTRUCTION WITHOUT REVIEW BY A QUALIFIED ENGINEER Date Sn/2008 / i ·' Page I Q~STONE ~ ~IIETAININGWALLSYSTEMS RETAINING WALL DESIGN Layer 3 2i I Version 3.5.1 Build 124 SEISMIC DESIGN, Div!, Chap 5 Project: Rosemonte East Renton Project No: KE040766B Date: 8/712008 Designer: SGB Case: Case I Design Method: AASHT0-96 (modified soil interface) Design Parameters Soll Parameters: Reinforced Fill Retained Zone Foundation Soil Reinforced Fill Type: A. 32 36 32 Silts & sands .£. 0 0 0 Unit Fill: Crushed Stone, I inch minus .:r:.._n£f 120 135 120 1~ Peak Acceleration= 0.2 I g Vertical Acceleration= 0.00 g Factors of Safety (seismic are 75% of static) sliding: l.50/1.13 pullout: overturning: 2.00/1.50 shear: bearing: 2.00/1.SO bending: Reinforcing Parameters: Strata-Grid Geogrids Tutt RFcr RFd RFid SG350 4350 1.61 I.JO 1.05 l.50/1.13 I.SO 1.50 LTDS 2339 AnalysisWall No. JC max 6.5 feet lt/gJ, 110 surcharge Unit Type: Standard 21.5" I I 20.00 pcf leveling Pad: Crushed Stone Wall Ht: 6.50ft Level Backfill Offset: 10.00 uncertainties: connection: Serviceability: l.50/1.13 l.50/1.13 1.00 /NA FS Tai Ci 1.50 I 560/3348 0.90 Cds 0.90 Case: Case J Wall Batter: 4.40 deg. embedment: 2.00 ft .. 1 Su,-charge: LL: 0 psf uniform surcharge Load Width: I 00.00 ft DL: 0 psf uniform surcharge Load Width: 100.00ft Results: Sliding Overturning Factors of Safety: 4.98/2.11 I 3.3314.24 Calculated Bearing Pressure: 785 I 785/95 I psf Eccentricity at base: 0.15 ft/0. 73 ft Reinforcing: (ft & lbs/ft) Height 4.67 2.67 0.67 Length 7.0 7.0 7.0 Cale. Tension 2461503 460 I 882 Reinf. Type SG350 SG350 SG350 Reinforcing Quantities (no waste included): SG350 2.33 sy/ft Beari11g 22.55/16.4/ Allow Ten Tai J 560/3348 ok 1560/3348 1560/3348 ok ~ 7.7914.49 Pk Conn Tel /169/1559 ok 2651/3535 ok Bending 1/.09/2./6 Serv Conn Tse 1278/ NIA ok 2779/NIA ok NOTE: THESE CALCULATIONS ARE FOR PRELIMINARY DESIGN ONLY AND SHOULD NOT BE USED FOR CONSTRUCT/ON WITHOUT REVIEW BY A QUALIFIED ENGINEER Date snnoos Pullout FS 3.00//.17 ok NIA 8.3613.49 ok Page I " :., . ~ -~ Q-STONE ~ ,..-~AINING WAll fflTEMS RETAINING WALL DESIGN Version 3.5.1 Build 124 SEISMIC DESIGN, Div!, Chap 5 Layer 2 I Project: Rosemonte East Renton Project No: KE040766B Case:Case2 Design Method: AASHT0-96 (modified soil inte,face) Design Parameters Soil Parameters: _t Reinforced Fill 32 Retained Zone 36 Foundation Soil 32 Reinforced FUI Type: Silts & sands ..£. 0 0 0 .Ll!£f 120 135 120 Date: 817/2008 Designer: SGB Unit Fill: Crushed Stone. I inch minus Peak Acceleration= 0.21 g Vertical Acceleration= 0.00 g FacWrs of Safety (seismic are 75% of static) sliding: J.50/1.13 pullout: overturning: 2.00/1.50 shear: bearing: 2.00/1.50 bending: Reinforcing Parameters: Strata-Grid Geogrids J.50/1.13 1.50 1.50 Tull RFcr RFd RFid LTDS SG350 4350 /.6/ I.JO 1.05 2339 AnalysisWa/1 No. JC 4.5' wit/r 110 surc/rarge Unit Type: Standard 21.5'' I 120.00 pcf leveling Pad: Crushed Stone Wall Ht: 4.50 ft Level Backfill Offset: 10.00 WICertainties: connection: Serviceability: l.50/1.13 l.50/1.13 1.00 /NA FS Tai Ci 1.50 1560/3348 0.90 Cds 0.90 Case: Case 2 Wall Batter: 4. 40 deg. embedment: 0.50 ft Surcharge: LL: 0 psfuniform surcharge Load Width.· I 00. 00 ft DL: 0 psf uniform surcharge Load Width: I 00. 00 ft Results: Slidllrg Overtrm1il1g Factors of Safety: 7.2813.09 27.8418.86 Calculated Bearing Pressure: 533 I 533/579 psf Eccentricity at base: 0.04 ft/0.32 ft Reinforcing: (ft & lbs/ft) Height 3.33 2.00 Length 7.0 7.0 Cale. Tension 56 I 241 282 I 500 Relnf. Type SG350 SG350 Reinforcing Quantities (no waste included): SG350 1.56 sy!ft Bear/11g 26.12/22.30 Allow Ten Ill! 1560/3348 ok 1560/3348 ok S/rear 35.58 /15.39 Pk Conn Tel 1134/15/2 ok /2041/605 ok Be,idi,ig 26.6613.98 Serv Conn Tse 1253/ NIA ok /303/ NIA ok NOTE: THESE CALCULATIONS ARE FOR PRELIMINARY DESIGN ONLY AND SHOULD NOT BE USED FOR CONSTRUCTION WITHOUT REVIEW BY A QUALIFIED ENGINEER Date 8/7/2008 Pullout FS >JO!I.89ok 5.0812.30 ok Page 1 ,.,, .'·' .,\ !?· ,~,.. • < '1 • ;"< ,i.,.;. ·~-~ . VJ.STONE ~ ~~NBWA1LSYSTEMS RETAINING WALL DESIGN Version 3.5.1 Build 124 SEISMIC DESIGN, Div!, Chap 5 Project: Rosemonte East Renton Project No: KE040766B Case: Case 3 Design Method: AASHT0-96 (modified soil inte,face) Design Parameters Soll Parameters: _l Retained Zone 36 0 Foundation Soil 32 0 Unit Fill: Crushed Stone, I inch minus .L.J!g 135 120 Date: 8/712008 Designer: SGB Peak Acceleration= 0.21 g Vertical Acceleration= 0.00 g I " l.50/1.13 J.50/1.13 1.00 /NA Factors of Safety (seismic are 75% of static) sliding: l.50/1.13 pullout: overturning: 1.50/0.00 shear: bearing: 2.00/1.50 bending: AnalyslsWall No. 3C 2.5' wall no surcharge l.50/1.13 1.50 1.50 Unit Type: Standard 21.5" / 120.00 pcf Leveling Pad: Crushed Stone Wall Ht: 2.50 ft Level Backfill Offset: 10.00 Surcharge: LL: 0 psfunifonn surcharge Load Width: 100.00 ft Results: Sliding Overturning Factors of Safety: 4.62/1.65 6.55/1.73 Calculated Bearing Pressure: 31II311/451 psf Eccentricity at base: 0.06 ft/0.48 ft uncertainties: connection: Serviceability: Case: Case 3 Wall Batter: 4.40 deg. embedment: 0.50 ft DL: 0 psf unifonn surcharge Load Width: I00.00 ft Bearing 21.63/11.52 Shear NIA Bending N/A NOTE: THESE CALCULATIONS ARE FOR PREl/MINARY DESIGN ONLY AND SHOULD NOT BE USED FOR CONSTRUCT/ON WITHOUT REVIEW BY A QUAl/FIED ENGINEER Date 817/2008 ! • £ Page I Q~STONE ~ ~REIAINJNOWALLSISTEMS RETAINING WALL DESIGN Version 3.5.1 Build 124 SEISMIC DESIGN, Div!, Chap 5 Project: Rosemonte -East Renton Project No: KE040766B Case: Case I Design Method: AASHT0-96 (modified soil interface) Design Parameters Soll Parameters: j_ ..£. Retained Zone 36 0 Foundation Soil 32 0 Unit Fill: Crushed Stone, I inch minus .L..filf 135 120 Date: 8/712008 Designer: SGB Peak Acceleration= 0.21 g Vertical Acceleration= 0.00 g Factors of Safety (seismic are 75% of static) sliding: l.50/1.13 pullout: overturning: 1.50/0.00 shear: bearing: 2.00/1.50 bending: 1.5011.13 1.50 1.50 uncertainties: com1ection: Serviceability: 1.5011.13 l.50/1.13 1.00 /NA AnalysisWall No. 4 2.5' with traffic surcharge S' behind wail Case: Case 1 Unit Type: Standard 21.5" / 120.00 pcf Leveling Pad: Crushed Stone Wall Ht: 2.50 ft Level Backfill Offset: 3.00 Surcharge: LL: 150 psf uniform surcharge Load Width: 100.00 ft Wall Batter: 4 .40 deg. embedment: 0.50 ft DL: I 00 psf uniform surcharge Load Width: 100.00 ft Results: Sliding Overturning Bearing Shear Bending Factors of Safety: 4.62/1.65 6.5511.73 21.63111.52 NIA NIA Calculated Bearing Pressure: 311I311/451 psf Eccentricity at base: 0.06 ft/0.48 ft NOTE: THESE CALCULATIONS ARE FOR PRELIMINARY DESIGN ONLY AND SHOULD NOT BE USED FOR CONSTRUCTION WITHOUT REVIEW BY A QUALIFIED ENGINEER Date 8/7/2008 Page 1 ,',,.,,,,,, .,:,.,~. •,•·.- i~STONE 1ch_ ~IIEIAININOWALLSYSTEMB RETAINING WALL DESIGN Version 3.5.1 Build 124 SEISMIC DESIGN, Div!, Chap 5 Layer 3 2 Project: Rosemonte -East Renton Project No: KE040766B Date: 8/712008 Designer: SGB Case: Case 2 Design Method: AASHT0-96 (modified soil inte,face) Design Parameters Soll Parameters: ..t Reinforced Fill 32 Retained Zone 36 Foundation Soil 32 Reinforced Fill Type: Silts & sands ..£. 0 0 0 Unit Fill: Crushed Stone, I inch minus .1...J!£f 120 135 120 Peak Acceleration= 0.21 g Vertical Acceleration= 0.00 g Factors of Safety (seismic are 75% ofstah·c) sliding: 1.50/1.l 3 pullout: overturning: 2.0011.50 shear: bearing: 2.00/1.50 bending: Reinforcing Parameters: Strata-Grid Geogrids Tuft RFcr RFd RFid SG350 4350 1.61 1.10 1.05 I.50/1.13 I.SO 1.50 LTDS 2339 uncertainties: connection: Serviceability: l.50/1.13 l.50/1.13 1.00 /NA FS Tai Ci 1.50 1560/3348 0.90 Cds 0.90 A11a/ysis:Wall No. 4 5.67' with traffic surcharge 5' be/,i11d wall Case: Case 2 U11it Type: Standard 21.5" I 120.00 pcf Wall Batter: 4.40 deg. Leveling Pad: Crushed Stone Wall Ht: 5.67 ft embedment: 0.50 ft level Backfill Offiet: 3.00 I --. ' --------- .. 1 Surcharge: LL: I 50 psf uniform surcharge Load Width: 100.00 ft DL: JOO psf1miform surcharge Load Width: I 00. 00 ft Results: S1idi11g Overtur11i11g Beari11g Shear Be11di11g Factors of Safety: 3.3412.11 8./ 714.57 /7.541/3.57 /2.64 /6.84 16.28 /4.83 Calculated Bearing Pressure: 738 I 733/824 psf Eccentricity at base: 0.06 ft/0.55 ft Reinforcing: (ft & lbs/ft) Cale. Allow Ten Pk Conn ServConn Height Length Tension Relnf, Ty11e Tai Tel Tse 4.67 6.5 67 I 201 SG350 I 560/3348 ok 1126/1501 ok 1247/N/A ok 2.67 6.5 201 I 386 SG350 1560/3348 ok 1230/1640 ok /322/N/A ok 0.67 6.5 267/491 SG350 1560/3348 ok /334//779ok 1396/ NIA ok Reinforcing Quantities (110 waste included): SG350 2.17 sy/ft NOTE: THESE CALCULATIONS ARE FOR PRELIMINARY DESIGN ONLY AND SHOULD NOT BE USED FOR CONSTRUCTION WITHOUT REVIEW BY A QUALIFIED ENGINEER Date 8/7/2008 Pullout FS 5.01//.34 ok 6.94/2.88 ok > /0/4.83 ok ij~STONE ~ ~RETAININGWALLSYBTEMS RETAINING WALL DESIGN ' Version 3.5.1 Build 124 SEISMIC DESIGN, Div!, Chap 5 Project: Rosemonte -East Renton Project No: KE040766B Date: 8/712008 Designer: SGB Case: Case I Design Method: AASHT0-96 (modified soil inte,face) Design Parameters Soll Parameters: Reinforced Fill Retained Zone Foundation Soil Reinforced Fill Type: Unit Fili: .1. 32 36 32 Silts & sands 0 0 0 Crushed Stone, I inch minus .l'....J!£f /20 /35 /20 Peak Acceleration= 0.21 g Vertical Acceleration= 0.00 g Factors of Safety (seismic are 75% of static) sliding: I.SO/LI 3 pullout: overturning: 2.00/1.50 shear: bearing: 2.00/1.50 bending: Reinforcing Parameters: Strata-Grid Geogrids Tull RFcr RFd RFid SG350 4350 1.6/ I.JO 1.05 l.50/1.13 I.SO 1.50 LTDS 2339 A11alysis:Wall No. 1 A 5' wit/, 2: 1 slope above for 8 feet Unit Type, Stmzdard 21.5" I 120.00 pcf Leveling Pad, Crushed Stone Wall Ht, 5.00 ft BackS/ope, 26.00 deg. slope, uncertainties: c0IU1ection: Serviceability: i.50/1.13 l.50/1.13 1.00 /NA FS Tai Ci 1.50 1560/3348 0.90 Cds 0.90 Case: Case I Wall Batter: 4.40 deg. embedment: I. 00 ft 8.00 ft long Surcharge: LL: 0 psfuniform surcharge Load Width: JOO.DO ft DL: 0 psf uniform surcharge Load Width, 100.00ft ResulJs: SliditJg Overtur11iug Facto1·s of Safety: 2.5411.48 5.3/12.78 Calculated Bearing Pressure: 729 I 729/940 psf Eccentricity at base: 0.16 ft/0.66 ft Reinforcing: (ft & lbs/ft) Layer Height 2 3.33 1.33 Length 5.0 5.0 Cale. Tension /60/366 397 I 725 Relnf. Type SG350 SG350 Reinforcing Quantities (no waste included): SG350 I. 11 sy/ft Bearing I 5.44110.07 Allow Ten Tai /560/3348 ok 1560/3348 ok Shear 12.75 /6.80 Pk Conn Tel /160//547 ok /265//686 ok Be11di11g 9.9/ /1.85 Serv Conn Tse 12721 NIA ok 1346/ NIA ok NOTE: THESE CALCULATIONS ARE FOR PRELIMINARY DESIGN ONLY AND SHOULD NOT BE USED FOR CONSTRUCTION WITHOUT REVIEW BY A QUALIFIED ENGINEER Date &n/2008 (fil[g@[g0W[g[g) AUG 127nnA ct~. D.Q.ES. Pullout FS 4.57/1.60 ok 4.3711.92 ok Page I ij~STONE ~~ ~RaAININGWALLSYIITTMS RETAINING WALL DESIGN Layer 2 I Version3.5.1 Build 124 SEISMIC DESIGN, Div!, Chap 5 Project: Rosemonte -East Renton Project No: KE040766B Date: 8/7/2008 Designer: SGB Case: Case 1 Design Method: AASHT0-96 (modified soil i11te1face) Design Parameters Soll Parameters: j_ Reinforced Fill 32 Retained Zone 36 Foundation Soil 32 Reinforced Fill Type: Silts & sands ..£_ 0 0 0 Unit Fill: Crushed Stone, I inch minus .l'..J!£f 120 135 120 Peak Acceleration= 0.21 g Vertical Acceleration= 0.00 g Factors of Safety (seismic are 75% of static) sliding: l.50/1.13 pullout: overturning: 2.00/1.50 shear: bearing: 2.00/1.50 bending: Reinforcing Parameters: Strata-Grid Geogrids Tuft RFcr RFd RFid SG350 4350 1.61 I.JO I.OJ A11a/ysisffa/l No. 1B 5.67' wit/I 110 s11rc/large l.50/1.13 I.SO I.SO LTDS 2339 U11it Type: Sta11dard 21.5" I 120.00 pcf Leveling Pad: Crushed Stone Wall Ht: 5.67 ft level Backfill Offset: 0. 00 uncertainties: coIUlection: Serviceability: l.50/1.13 l.50/1.13 1.00 /NA FS Tai Ci 1.50 J 560/3348 0.90 Cds 0.90 Case: Case 1 Wall Batter: 4.40 deg. embedment: I. 00 fl Surcharge: LL: 0 psf uniform surcharge load Width: 100.00 ft DL: 0 psf u1riform surcharge load Width: I 00. 00 ft Res11/ts: Sliding Overtumi11g Factors of Safety: 4.89/2.07 12.8714.09 Calculated Bearing Pressure: 686 I 686/838 psf Eccentricity at base: 0.13 ft/0.65 ft Reinforcing: (ft & lbs/ft) Height 4.00 2.00 Length 6.0 6.0 Cale. Tension 119/350 4181745 Reinf. Type SG350 SG350 Reinforcing Quantities (no waste included): SG350 1.33 sylft Beari11g /9.20/13.49 Allow Ten Tai 1560/3348 ok 1560/3348 ok Shear 16.95 /8.69 Pk Conn Tel 1/60/1547 ok /265/1686 ok Bending 13.2812.46 ServConn Tse 1272/NIA ok 1346/ NIA ok NOTE: THESE CALCULATIONS ARE FOR PRELIMINARY DESIGN ONLY AND SHOULD NOT BE USED FOR CONSTRUCT/ON WITHOUT REVIEW BY A QUALIFIED ENGINEER Date 8/7/2008 Pullout FS 4.35/1./8 ok 3.85/1.73 ok Page I \%1 ~STONE \J~ ~~NINGWALLSYSTEMS RETAINING WALL DESIGN Layer 4 3 2 I Version 3.5.1 Build 124 SEISMIC DESIGN, Div!, Chap 5 Project: Rosemonte -East Renton Project No: KE040766B Date: 8/7/2008 Designer: SGB Case: Case I Design Method: AASHT0-96 (modified soil inte,face) Design Parameters Soil Parameters: ~ Reinforced Fill 32 Retained Zone 36 Foundation Soil 32 Reinforced Flll Type: Silts & sands ..£. 0 0 0 Unit Fill: Crushed Stone, 1 inch minus .L.J!£f 120 /35 120 Peak Acceleration= 0.2 I g Vertical Acceleration= 0.00 g Factors of Safety (seismic are 75% of static) sliding: l.50/1.13 pullout: overturning: 2.00/1.SO shear: bearing: 2.00/1.50 bending: Reinforcing Parameters: Strata-Grid Geogrids Tult RFcr RFd RFid SG350 4350 /.6/ I.IO 1.05 l.50/1.13 1.50 I.SO LTDS 2339 A11alysis.Wal/ No. 212.33' with traffic surcharge Unit Type: Sta11dm·d 2/.5" 1120.00 pcf Leveling Pad: Crushed Stone Wall Ht: 12.33 ft level Backfill Offset: 5.00 uncertainties: connection: Serviceability: l.50/1.13 l.50/1.13 1.00 /NA FS Tai Ci 1.50 /560/3348 0.90 Cds 0.90 Case: Case 1 Wall Batter: 4.40 deg. embedment: 3.00 ft ! Surcharge: LL: 150 psf umfo,.m surcharge load Width: 100.00ft DL: JOO psfwziform sr1rcharge Load Width: 100.00ft Res111ts: Slidi,ig Overturnimz Factors of Safety: 2. 76/1.45 4.86/2.12 Calculated Bearing Pressure: 169/ I /69712549 psf Eccentricity at base: 0.60 ft/2.08 ft Reinforcing: (ft & lbs/ft) Cale. Height Length Tension Reinf. Tyge 10.67 9.5 150/414 SG350 8.00 9.5 3861778 SG350 5.33 9.5 624 I 1144 SG350 2.67 9.5 14191202/ SG350 Reinforcing Quantities (no waste included): SG350 4.22 sy!ft Bearl11g 13.8317.07 Allow Ten Tai I 560/3348 ok 1560/3348 ok J560/3348ok I 560/3348 ok Shear 5.3913.48 Pk Conn Tel 1/60/1547 ok 1299/1732 ok /438/1918 ok /57712103 ok Be11di11g 8.45 12.47 Serv Conn Tu 1272/ NIA ok 1371/N/Aok 14701 NIA ok 1569/ NIA ok NOTE: THESE CALCULATJONS ARE FOR PRELIMINARY DESlGN ONLY AND SHOULD NOT BE USED FOR CONSTRUCTION WJTHOUT REVIEW BY A QUALIFJED ENGINEER Date Bn/2008 Pullout FS 5.8411.70 ok 6.9812.77 ok 8.69/3.79 ok 6.3813.58 ok Page! ~-TONE v .. -~~DININBWALLSYBTEMS RETAINING WALL DESIGN Version 3.5.1 Build 124 SEISMIC DESIGN, Div!, Chap 5 Project: Rosemonte East Renton Project No: KE040766B Date: 8/712008 Designer: SGB Case: Case l . Design Method: AASHT0-96 (modified soil interface) Design Parameters Soll Parameters: Reinforced Fill Retained Zone Foundation Soil Reinforced Fill Type: j_ 32 36 32 Silts & sands .£. 0 0 0 Unit Fill: Crushed Stone, 1 inch minus .LJ!g 120 135 120 Peak. Acceleration= 0.21 g Vertical Acceleration= 0.00 g Factors of Safety (seismic are 7 5% of static) sliding: 1.50/ 1.13 pulloul: overturning: 2.00/1.50 shear: bearing: 2.00/1.50 bending: Reinforcing Parameters: Strata-Grid Geogrids 1.50/l.13 I.SO 1.50 Tult RFcr RFd RFid LTDS SG350 4350 1.61 1.10 1.05 2339 uncertainties: connection: Serviceability: l.50/1.13 l.50/1.13 1.00 /NA FS Ta/ Ci 1.50 1560/3348 0.90 Cds 0.90 A11alysis.Wa/l No. 3A max 3.67 feet 1,/gl, 17 degree slope surcharge Case: Case 1 Unit Type: Standard 21.5" I 120.00 pcf leveling Pad: Crushed Stone Wall Ht: 3.67 ft BackS/ope: 17. 00 deg. slope, Wall Batter: 4.40 deg. embedment: 1.00 ft l 0. 00 ft long i __ .,.. ________ _ Surcharge: LL: 0 psf uniform surcharge Load Width: /00.00 ft DL: 0 psf uniform surcharge Load Width: 100.00 ft Results: Slidi11g Oi,ert11r11i11g, Bearing, ~ Be11di11g, Facto,~ of Safety: 4.3512.32 13.2216.34 25.83/22.54 32.6616.58 12./711.61 Calculated Bearing Pressure: 494 I 4941536 psf Eccentricity at base: 0.00 ft/0. 19 ft Reinforcing: (ft & lbs/ft) Cale. Allow Ten Pk Conn Serv Conn Layer Height Length Tension Reinf. Tl'.~e Tai Tel Tse /160//547 ok 1272/N/A ok J 2.00 5.5 246 I 572 SG350 J 560/3348 ok Reinforcing Quantities (no wllste included): SG350 0.61 sy/ft NOTE: THESE CALCULATIONS ARE FOR PRELIMINARY DESIGN ONLY AND SHOULD NOT BE USED FOR CONSTRUCTION WITHOUT REVlEW BY A QUAL/FlED ENGINEER Dnte sn/2008 / Pullout FS 4.0811.40 ok Page I wl~TONE ~ ~liTIIIIIN6WAU.SlST£MS RETAINING WALL DESIGN Layer 2 Version 3.5.1 Build 124 SEISMIC DESIGN, Div!, Chap 5 Project: Rosemonte East Renton Project No: KE040766B Date: 8/7/2008 Designer: SGB Case: Case I Design Method: AASHT0-96 (modified soil interface) Design Parameters Soll Parameters: Reinforced Fill Retained Zone Foundation Soil Reinforced Fill Type: ..t 32 36 32 Silts & sands .£. 0 0 0 Unit Fill: Crushed Stone, I inch minus ..LJ!.sf 120 135 120 PeakAcceieration = 0.2 I g Vertical Acceleration= 0.00 g Facto,~ of Safety (seismic are 75% of static) sliding: 1.5011.13 pullout: overturning: 2.0011.50 shear: bearing: 2.0011.50 bending: Reinforcing Parameters: Sh·afa.Grid Geogrids Tult RFcr RFd RFid SG350 4350 l.61 I.JO 1.05 1.5011.13 I.SO 1.50 ill2S 2339 uncertainties: coIU1ection: Serviceability: l.5011.13 1.5011.13 1.00 /NA FS Tai Ci 1.50 1560/3348 0.90 Ql1. 0.90 Analysis;Wa/1 No. 3A max 3.67 feet l,igl, 17 degree slope surcharge Case: Case 1 Unit Type: Standard 21.5" I 120.00 pc[ leveling Pad: Crushed Stone Wall Ht: 3.67 fl BackS/ope: 17.00 deg. slope, Wall Batter: 4.40 deg. embedment: 1.00ft I 0. 00 fl long Surcharge: LL: 0 psf uniform surcharge Load Width: I 00. 00 fl DL: 0 psf uniform surcharge Load Width: 100.00ft Results: Sliding Overtur11iHg Beari11g S!,ear Be11di11g Facto1>· of Safety: 4.3512.32 13.2216.34 25.83122.54 26.9716.58 12.17 /1.61 Calculated Bearing Pressure: 494 I 494/536 psf Eccentricity at base: 0.00 ft/0.19 ft Reinforcing: (ft & lbs/ft) Cale. Allow Ten Pk Conn ServConn Height Length Tu!llim Relnf. TIJ!e Tai Tel ~ 2.00 5.5 /001246 SG350 1560/3348 ok l/60//547ok 12721 NIA ok 0.67 5.5 146 I 326 SG350 1560/3348 ok J230//640ok 1322/ NIA ok Reinforcing Quantities (no waste included): SG350 1.22 syl[t NOTE: THESE CALCULATIONS ARE FOR PRELIMINARY DESIGN ONLY AND SHOULD NOT BE USED FOR CONSTRUCT/ON WITHOUT REVIEW BY A QUALIFIED ENGINEER Date Sn/2008 Pullout fill >/0/3.27 ok >/0/4.37 ok Page I rl~STONE ~ ~mAININGWALLSYSTEMS RETAINING WALL DESIGN Layer 3 2i I Version 3.5.1 Build 124 SEISMIC DESIGN, Div I, Chap 5 Project: Rosemonte East Renton Project No: KE040766B Date: 817/2008 Designer: SGB Case: Case 2 Design Method: AASHT0-96 (modified soil interface) Design Parameters Soil Parameters: Reinforced Fill Retained Zone Foundation Soil Reinforced Flll Type: ..t. 32 36 32 Silts & sands .£. 0 0 0 Unit Fill: Crushed Stone, I inc/1 minus .l'...J!£f /20 /35 /20 Peak Acceleration= 0.21 g Vertical Acceleration= 0.00 g Factoi, of Safety (seismic are 75% of static) sliding: J.50/1.13 pullout: overturning: 2.00/1.50 shear: bearing: 2.00/1.50 bending: Reinforcing Parameters: Strata.Grid Geogrids Tult RFcr RFd RFid SG350 4350 /.61 I.JO 1.05 J.50/1.13 1.50 1.50 LTDS 2339 A11alysisWall No. 3A 5.67' will, 17 degl'ee slope surcharge Unit Type: Standard 2/.5" I I 20.00 pcf Leveling Pad: Crushed Stone Wall Ht. 5.67 ft BackS/ope. I 7.00 deg. slope, uncertainties: connection: Serviceability: l.50/1.13 J.50/1.13 1.00 /NA FS Tai Ci 1.50 I 560/3348 0.90 Case: Case 2 Cds 0.90 Wall Batter: 4.40 deg. embedment: 1.00 ft I 0. 00 ft long .. 1 Surcharge: LL: 0 psfumfonn st1rcharge load Width: /00.00 ft DL: 0 psf uniform surcharge Load Width: I 00. 00 ft Results: S1idi11g Overt11r11i11g Factors of Safety: 3.1811.53 6.84/2. 72 Calculated Bearing Pressure: 7671767/1053 psf Eccentricity at base: 0.14 ft/0.82 ft Reinforcing: (fl & lbs/fl) Height 4.00 2.67 1.33 Length 5.5 5.5 5.5 Cale. Tension 167 /390 4271808 Relnf. Type SG350 SG350 SG350 Reinforcing Quantities (no waste included): SG350 1.83 sy/ft Beari,ig 15.98/9.30 Allow Ten Tai I 560/3348 ok 1560/3348 1560/3348 ok S/rear 16.02 17.47 Pk Conn Tel 1160/1547 ok 2530/3373 ok Be11di1Jg 12.0211.87 Serv Conn Tse 12721 NIA ok 2693/NIA ok NOTE: THESE CALCULATIONS ARE FOR PRELIMINARY DESIGN ONLY AND SHOULD NOT BE USED FOR CONSTRUCTION WITHOUT REVIEW BY A QUALIFIED ENGINEER Date Bn/2008 Pullout FS 4./811.43 ok NIA 5.0912./5 ok Page 1 tl~STONE ~ ~REIAININGWAU.fflTEMS RETAINING WALL DESIGN Version 3.5.1 Build 124 SEISMIC DESIGN, Div!, Chap 5 Project: Rosemonte East Renton Project No: KE040766B Case: Case 1 Design Method: AASHT0-96 (modified soil i11te1face) Design Parameters Soll Parameters: Reinforced Fill Retained Zone Foundation Soil Reinforced Fill Type: j_ 32 36 32 Silts & sands .£. 0 0 0 Unit Fili: Crushed Stone, 1 inch minus .LJ!£f 120 135 120 Date: 8/7/2008 Designer: SGB Peak Acceleration= 0.21 g Vertical Acceleration= 0.00 g Factors of Safety (seismic are 7 5% of static) sliding: l.50/1.13 pullout: overturning: 2.00/1.50 shear: bearing: 2.00/l.50 bending: Reinforcing Parameters: Strata-Grid Geogrids Tult RFcr RFd RFid SG350 4350 1.61 I.JO 1.05 l.50/1.13 1.50 1.50 LTDS 2339 A11alysidYall No. 3B max 3.5 feet high 110 surcharge U11it Type: Standard 21.5" I 120.00 pc/ Leveling Pad: Crushed Stone Wall Ht: 3.50 ft Level Backfill Offset: I 0. UU Surcharge: LL: 0 psf uniform surcharge Load Width: /00.00 ft Results: Sl/di11g Overt111·11i11g Factors a/Safety: 8.7213.66 39.69/12.48 Calculated Bearing Pressure: 413 I 4 I 3/438 psf Eccentricity at base: 0.02 ft/0.20 ft Reinforcing: (ft & lbs/ft) uncertainties: connection: Serviceability: 1.S0/1.13 l.50/1.13 1.00 /NA FS Tai Ci 1.50 1560/3348 0.90 Cds 0.90 Case: Case I Wall Batter: 4.40 deg. embedment: 1.00 ft DL: 0 psfuniform surcharge Load Width: I 00. 00 ft Bearl,rg 35.08131.60 Shear 43.89 /10.94 Be11di11g 16.35 /2.84 " I Layer Height I 2.00 Length 6.5 Cale. Tension 205 I 492 Reinf. Type SG350 Allow Ten Tai I 560/3348 ok Pk Conn Tel 1152/1535 ok ServConn Tse 12661 NIA ok Reinforcing Quantities (110 waste included): SG350 0. 72 sy!ft NOTE: THESE CALCULATIONS ARE FOR PRELIMINARY DESIGN ONLY AND SHOULD NOT BE USED FOR CONSTRUCTION WITHOUT REVIEW BY A QUALIFIED ENGINEER Date 8/7/2008 [ Pullout FS 3.71/1.24 ok Page I Layer 2 I RETAINING WALL DESIGN Version3.5.I Build 124 SEISMIC DESIGN, Divl, Chap 5 Project: Rosemonte East Renton Project No: KE040766B Date: 817/2008 Designer: SGB Case: Case 2 Design Method: AASHT0-96 (modified soil inte,face) Design Parameters Soll Parameters: Reinforced Fill Retained Zone Foundation Soil Reinforced Fill Type: .i. 32 36 32 Silts & sands .£. 0 0 0 Unit Fill: Crushed Stone, I inch minus .I..J!g /20 /35 120 Peak Acceleration= 0.21 g Vertical Acceleration= 0.00 g Factors of Safety (seismic are 75% of static) sliding: l.50/1.13 pullout: overturning: 2.00/1.50 shear: bearing: 2.00/l.50 bending: Reinforcing Parameters: Su·ata-Grid Geogrids SG350 Tult 4350 RFcr /.6/ RFd I.JO RFid 1.05 A11alysis:Wall No. 3B 5.67' with uo s111'cl,arge l.50/1.13 1.50 1.50 LTDS 2339 Unit Type: Standard 2 /.5" I I 20.00 pcf leveling Pad: Crushed Stone Wall Ht: 5.67 ft level Backfill Offset: 10.00 uncertainties: connection: Serviceability: l.50/1.13 l.50/1.13 1.00 /NA FS Tai Ci 1.50 1560/3348 0.90 Cds 0.90 Case: Case 2 Wall Batter: 4. 40 deg. embedme11t.-1.00 ft Surcharge: LL: 0 psf uniform surcharge load Width: 100.00ft DL: 0 psf uniform surcharge load Width: JOO. 00 ft Results: Slidi11g Overt11n1i11g Factors of Safety: 5.3112.25 I 5./1/4.81 Calculated Bearing Pressure: 682 1682/804 psf Eccentricity at base: 0.11 ft/0.59 ft Reinforcing: (ft & lbs/ft) Height 4.00 2.00 Length 6.5 6.5 Cale. Tension 119/357 4181737 Rein[, Type SG350 SG350 Reinforcing Quantities (110 waste included): SG350 1.44 sy/ft Bearing 20. 76/15.46 Allow Ten Tai I 560/3348 ok I 560/3348 ok S/iear 16.96/8.71 Pk Conn Tel /160//547 ok 1265/1686 ok Be11di11g 13.2812.46 Serv Conn Tse 1272/ NIA ok 1346/ NIA ok NOTE: THESE CALCULATIONS ARE FOR PREL/MJNARY DESIGN ONLY AND SHOULD NOT BE USED FOR CONSTRUCT/ON WITHOUT REVIEW BY A QUAL/FIED ENGINEER Dote Bn/2008 i Pullout FS 5.29//.41 ok 4.4512.02 ok ' ~·. \l~STONE \fu. ~mAININGWALLSlSTEMS RETAINING WALL DESIGN Version 3.5.1 Build 124 SEISMIC DESIGN, Div!, Chap 5 Layer 3 2i I Project: Rosemonte East Renton Project No: KE040766B Date: 817/2008 Designer: SOB Case: Case 3 Design Method: AASHT0-96 (modified soil interface) Design Parameters Soll Parameters: Reinforced Fill Retained Zone Foundation Soil Reinforced Fill Type: j_ 32 36 32 Silts & sands ..£.. 0 0 0 Uuit Fill: Crushed Stone, 1 inch minus L.J!tl /20 /35 /20 Peak Acceleration= 0.21 g Vertical Acceleration= 0.00 g Factors of Safety (seismic are 75% of static) sliding: l.50/1.13 p~llout: overtuming: 2.00/1.50 shear: hearing: 2.00/1.50 bending: Reinforcing Parameters: Strata-Grid Geogrids l.50/1.13 1.50 1.50 Tull RFcr RFd RFid LTDS SG350 4350 1.61 I.JO J.05 2339 A11alysisWall No. 3B 7' wall 2:1 slope surcharge/or 10' Unit Type: Standard 21.5" I I 20.00 pcf leveling Pad· Crushed Stone Wall Ht: 7.00 ft BackS/ope: 26. 00 deg. slope, uncertainties: connection: Serviceability: l.50/1.13 l.50/1.13 1.00 /NA FS Tai Ci 1.50 /560/3348 0.90 Case: Case 3 Cds 0.90 Wall Batter: 4. 40 deg. e111bedme11t: 0.50 ft I 0. 00 ft long Surcharge: LL: 0 psf uniform surcharge Load Width: 100.00ft DL: 0 psf uniform surcharge Load Width: /00.00 ft Resulls: Slidi11g Overturning Factors of Safety: 2.33//.3/ 4.4312.21 Calculated Bearing Pressure: 1077 I /0771/542 psf Eccentricity at base: 0.37 ft/1.21 ft Reinforcing: (ft & lbs/ft) Cale. Height Length Tension Reinf. Tyl!• 5.33 6.5 305/6/3 SG350 3.33 6.5 SG350 1.33 6.5 799(/379 SG350 Reinforcing Quantities (110 waste included): SG350 2.17 sy(Jt Beari11g /0.99/5.70 Allow Ten Tai 1560/3348 ok I 56013348 1560/3348 ok Shear 6.7014.72 Pk Conn Tel J / 60/1547 ok 2634/351/ ok Be11di11g 9.69//.86 ServConn Tse 1272/ NIA ok 2767/N/A ok NOTE: THESE CALCULATIONS ARE FOR PRELIMINARY DESIGN ONLY AND SHOULD NOT BE USED FOR CONSTRUCTION WITHOUT REVIEW BY A QUALIFIED ENGINEER Date 817/2008 Pullout FS 3.85/1.53 ok NIA 5.0412.34 ok Page I ·.•, ·"'-' , ' ti.STONE ~ ~R'nAOOllGWALLSYSTEMS RETAINING WALL DESIGN Version 3.5.1 Build 124 SEISMIC DESIGN, Div!, Chap 5 Project: Rosemonte East Renton Project No: KE040766B Case: Case4 Design Method: AASHT0-96 (modified soil inte,face) Design Parameters Soil Parameters: j_ .£. Retained Zone 36 0 Foundation Soil 32 0 Unit Fill: Crushed Stone, I inch minus .LJ!£f 135 120 Date: 81712008 Designer: SGB Peak Acceleration= 0.2 I g Vertical Acceleration= 0.00 g Factors of Safety (seismic are 75% of static) sliding: l.50/1.13 pullout: overturning: 1.50/0.00 shear: bearing: 2.00/1.SO bending: l.50/1.13 1.50 1.50 AnalyslsWall No. 3B 2.5' wall 2:1 slope surcharge for 10' Unit Type: Standard 21.5" 1120.00 pcf Leveling Pad: Crushed Stone Wall Ht: 2.50 ft BackSlope: 26.00 deg. slope, Surcharge: LL: 0 psfuniform surcharge Load Width: 100.00 ft Results: Slldlng Overturning Factors of Safety: 3.7911.25 5.3711.37 Calculated Bearing Pressure: 301 I 301/600 psf Eccentricity at base: 0.01 ft/0.60 ft uncertainties: connection: Serviceability: 1.5011.13 1.5011.13 1.00 /NA Case: Case 4 Wall Batter: 4.40 deg. embedrnent: 0. 50 ft 10. 00 ft long D L: 0 psf lllllfonn surcharge Load Width: 100.00 ft Bearing 22.9on.9o Shear NIA Bending NIA NOTE: THESE CALCULATIONS ARE FOR PRELIMINARY DESIGN ONLY AND SHOULD NOT BE USED FOR CONSTRUCT/ON WITHOUT REVIEW BY A QUALIFIED ENGINEER Date Sn/2008 ' ! Page I \;l-TONE ~ ~BmlNINll WALL SYSTEMS RETAINING WALL DESIGN Version3.5.l Build 124 SEISMIC DESIGN, Div!, Chap 5 Project: Rosemonte East Renton Project No: KE040766B Date: 8/712008 Designer: SGB Case: Case I Design Method: AASHT0-96 (modified soil interface) Design Parameters Soil Parameters: Reinforced Fill Retained Zone Foundation Soil Reinforced Fill Type: .i. 32 36 32 Silts & sands £. 0 0 0 Unit Fill: Crushed Stone, I inch minus 1....l!£!: 120 135 /20 Peak Acceleration= 0.21 g Vertical Acceleration= 0.00 g Factors of Safety (seismic are 75% of static) sliding: i.50/1.13 pullout: overtuming: 2.00/1.50 shear: hearing: 2.00/1.50 bending: Reinforcing Parameters: Strata-Grid Geogrids Thf1 RFcr RFd RFid SG350 4350 /.61 I.JO 1.05 i.50/1.13 I.SO 1.50 LTDS 2339 A11alysisWa/l No. JC max 6.5 feet /1/gil 110 s11rcilarge Unit Type: Standard 21.5" I I 20.00 pcf leveling Pad: Crushed Sto11e Wall Ht: 6.50ft Level Backfill Offset: 10.00 uncertainties: connection: Serviceability: l.50/1.13 l.50/1.13 1.00/NA FS Tai Ci 1.50 /560/3348 0.90 Cds 0.90 Case: Case I Wall Batter: 4.40 deg. embedmelll: 2.00ft Surcharge: LL: 0 psf unifonn surcharge load Width: 100.00 ft DL: 0 psfuniform surcharge Load Width, JOO. 00 ft Results: Slidi11g Overtumi!Jg Factors of Safety: 4.98/2. // I 3.3314.24 Calculated Bearing Pressure: 785 I 785195 I psf Eccentricity at base: 0.15 fl/0. 73 ft Reinforcing: (ft & lbs/ft) Layer Height 3 4.67 2i 2.67 I 0.67 Length 7.0 7.0 7.0 Cale. Tension 246 I 503 460 I 882 Reinf. Type SG350 SG350 SG350 Reinforcing Quantities (no waste included): SG350 2.33 sy/ft Beari11g 22.55//6.41 Allow Ten Tai 1560/3348 ok 1560/3348 1560/3348 ok Shear 7.7914.49 Pk Conn Tel 1/69/1559 ok 2651/3535 ok Be11di11g /1.0912./6 Serv Conn Tse 12781 NIA ok 2779/ NIA ok NOTE: THESE CALCULATIONS ARE FOR PRELIMINARY DESIGN ONLY AND SHOULD NOT BE USED FOR CONSTRUCTION WITHOUT REVIEW BY A QUAL/FIED ENGINEER Dnte annooa Pullout FS 3.00/1./7 ok NIA 8.3613.49 ok Page I \],.STONE ~~ ,...R'miNINOWAUSYSTEMS RETAINING WALL DESIGN Layer 2 I Version 3.5.1 Build 124 SEISMIC DESIGN, Div!, Chap 5 Project: Rosemonte East Renton Project No: KE040766B Date: 8/7/2008 Designer: SOB Case: Case 2 Design Method: AASHT0-96 (modified soil inte1face) Design Parameters Soil Parameters: Reinforced Fill Retained Zone Foundation Soil Reinforced Fill Type: .i. 32 36 32 Silts & sands ..£. 0 0 0 Unit Fill: Crushed Stone, J inch minus -1...Jlff 120 135 120 Peak Acceleration= 0.2 / g Verllcal Acceleration= 0.00 g Factors of Safety (seismic are 75% of static) sliding: l.50/1.13 pullout: overturning: 2.00/1.50 shear: bearing: 2.00/1.50 bending: Reinforcing Parameters: Strata-Grid Geogrids Tu/1 RFcr RFd RFid SG350 4350 l.61 l.10 1.05 AnalysisJVall No. 3C 4.5' >vit/1 110 surcharge l.50/1.13 1.50 1.50 LTDS 2339 Unit Type: Standard 11.5" I 120.00 pc/ Leveling Pad: Crushed Stone Wall Ht: 4.50 ft level Backfill Offset: I 0. 00 W1certainties: connection: Serviceability: l.50/1.13 l.50/1.13 1.00/NA FS Tai Ci 1.50 /560/3348 0.90 Cds 0.90 Case: Case 2 Wall Baller: 4.40 deg. embedment: 0.50 ft Surcha,·ge: LL: 0 psf uniform surcharge load Width.· I 00. 00 ft DL: 0 psfuniform surcharge load Width: 100.00ft Results: Slid/111, Overllm1i11g Factors of Safety: 7.2813.09 27.8418.86 Calculated Bearing Pressure: 533 I 533/579 psf Eccentricity at base: 0.04 ft/0.32 ft Reinforcing: (ft & lbs/ft) Height 3.33 2.00 Length 7.0 7.0 Cale. Tension 56 I 241 281 I 500 Reinf. Type SG350 SG350 Reinforcing Quantities (no waste included): SG350 1.56 sy/ft Beari11g 26.12/22.30 Allow Ten Tai 1560/3348 ok 1560/3348 ok Sllear 35.58 /15.39 Pk Conn Tel /134/1512 ok /204//605 ok Be11di11g 26.66 /3.98 Serv Conn Tse 1253/NIA ok /303/ NIA ok NOTE: THESE CALCULATIONS ARE FOR PRELIMINARY DESIGN ONLY AND SHOULD NOT BE USED FOR CONSTRUCT/ON WITHOUT REVIEW BY A QUALIFIED ENGINEER Date 8n/2008 Pullout FS > /0//.89 ok 5.0812.30 ok Page I F7A1 STONE ~ /ii,;7,1·· ., ... ~ REIAININO WALL SYSTEMS RETAINING WALL DESIGN Version 3.5.1 Build 124 SEISMIC DESIGN, Div!, Chap 5 Project: Rosemonte East Renton Project No: KE040766B Case: Case 3 Design Method: AASHT0-96 (modified soil inte,face) Design Parameters Soll Parameters: .!. Retained Zone 36 0 Foundation Soil 32 0 Unit Fill: Crushed Stone, I inch minus .1....J!tl 135 120 Date: 817/2008 Designer: SGB Peak Acceleration= 0.21 g Vertical Acceleration= 0.00 g Factors of Safety (seismic are 75% of static) sliding: 1.5011.13 pullout: overturning: 1.5010.00 shear: bearing: 2.00/1.50 bending: Analysis!rVall No. JC 2.5' wall no surcharge t.50/1.13 1.50 1.50 Unit Type: Standard 21.5" I 120.00 pcf Leveling Pad: Crushed Stone Wall Ht: 2.50 ft Level Backfill Offset: I 0.00 Surcharge: LL: 0 psf uniform suscharge Load Width: I 00.00 ft Results: Sliding Overturning Factors of Safety: 4.6211.65 6.5511.73 Calculated Bearing Pressure: 31II311/451 psf Eccentricity at base: 0.06 ft/0.48 ft uncertainties: connection: Serviceability: l.50/1.13 1.5011.13 1.00 /NA Case: Case 3 Wall Batter: 4.40 deg. embedment: 0.50 ft DL: 0 psfuniform surcharge Load Width: 100.00 ft Bearing 21.63111.52 Shear NIA Bending NIA NOTE: THESE CALCULATIONS ARE FOR PRELIMINARY DESlGN ONLY AND SHOULD NOT BE USED FOR CONSTRUCTION WJTHOUT REVIEW BY A QUALIFIED ENGINEER Date 8/712008 Page I \]~STONE ~~RmJNINGWALLSYSTEMS RETAINING WALL DESIGN Version 3.5.1 Build 124 SEISMIC DESIGN, Div!, Chap 5 Project: Rosemonte -East Renton Project No: KE040766B Date: 8/712008 Designer: SOB Case: Case 1 Design Method: AASHT0-96 (modified soil interface) Design Parameters Soll Parameters: j_ Retained Zone 36 0 Foundation Soil 32 0 Unit FIil: Crushed Stone, 1 inch minus .x..__ng 135 120 Peak Acceleration= 0.21 g Vertical Acceleration= 0.00 g Factors of Safety (seismic are 75% of static) sliding: J.50/1.13 pullout: overturning: 1.50/0.00 shear: bearing: 2.00/1.50 bending: l.50/1.13 1.50 1.50 uncertainties: connection: Serviceability: l.50/1.13 1.5011.13 1.00 /NA AnalysisWall No. 4 2.5' with traffic surcharge 5' behind wall Case: Case 1 Unit Type: Standard 21.5" I 120.00 pcf Leveling Pad: Crushed Stone Wall Ht: 2.50 ft Level Backfill Offset: 3.00 Surcharge: LL: 150 psfunifonn surcharge Load Width: 100.00 ft Results: Sliding Overturning Factors of Safety: 4.62/1.65 6.5511.73 Calculated Bearing Pressure: 311 I 311/45/ psf Eccentricity at base: 0.06 ft/0.48 ft Wall Batter: 4.40 deg. embedment: 0.50 ft DL: I 00 psf uniform surcharge Load Width: I 00.00 ft Bearing 21.63111.52 Shear NIA Bending NIA NOTE: THESE CALCULATIONS ARE FOR PRELIMINARY DESIGN ONLY AND SHOULD NOT BE USED FOR CONSTRUCTION WITHOUT REVIEW BY A QUALIFIED ENGINEER Date Bn/2008 Pnge I • ~-STONE 't:h. ~REDININGWAU.SYfflMS RETAINING WALL DESIGN Layer 3 2 I Version 3.5.1 Build 124 SEISMIC DESIGN, Div!, Chap 5 Project: Rosemonte -East Renton Project No: KE040766B Date: 8/712008 Designer: SOB Case: Case 2 Design Method: AASHT0-96 (modified soil interface) Design Parameters So0 Parameters: Reinforced Fill Retained Zone Foundation Soil Reinforced FIii Type: ..l 32 36 32 Silts & sands .£. 0 0 0 Unit Fill: Crushed Stone, 1 inch minus -1....Jl£f 120 /35 /20 Peak Acceleration= 0.21 g Vertical Acceleration= 0.00 g Factors of Safety (seismic are 75% of static) sliding: 1.50/1.l 3 pullout: overturning: 2.00/1.50 shear: bearing: 2.00/1.50 bending: Reinforcing Parameters: Strata-Grid Geogrids Tull RFcr RFd RFid SG350 4350 1.61 1.10 1.05 l.50/1.13 1.50 1.50 LTDS 2339 uncertainties: connection: Serviceability: l.50/1.13 l.50/1.13 1.00 /NA FS Tai Ci 1.50 /560/3348 0.90 Cds 0.90 A11alysisWall No. 4 5.67' ,vi/I, traffic surcliarge 5' beltittd wall Case: Case 2 Unit Type: Standard 21.5" I J 20.00 pcf Wall Batter: 4.40 deg. Leveling Pad: Crushed Stone Wall Ht: 5.67 ft embedment: 0.50ft Level Backfill Offiet: 3.00 Surcharge: LL: I 50 psf uniform surcharge Load Width: 100.00ft DL: I 00 psf uniform surcharge Load Width: I 00. 00 ft Results: Sliding Overt11mi11g Beari11g Shear Be11di11g Factors of Safety: 3.3412.11 8.1714.57 17.54//3.57 /2.64 /6.84 16.28 /4.83 Calculated Bearing Pressure: 738 I 7331824 psf Eccentricity at base: 0.06 ft/0.55 ft Reinforcing: (ft & lbs/ft) Cale. Allow Ten Pk Conn Serv Conn Height Length Tension Relnf. Ty(!e Tai Tel Tu 4.67 6.5 67 I 201 SG350 J 560/3348 ok 1126/1501 ok 1247/N/A ok 2.67 6.5 20/ I 386 SG350 1560/3348 ok /230//640 ok /322/N/A ok 0.67 6.5 267/49/ SG350 1560/3348 ok /334//779ok 1396/ NIA ok Reinfo1'cing Quantities (no waste included): S0350 2.17 sy/ft NOTE: THESE CALCULATIONS ARE FOR PRELIMINARY DESIGN ONLY AND SHOULD NOT BE USED FOR CONSTRUCTION WITHOUT REVIEW BY A QUALIFIED ENGINEER Date Kn/2008 Pullout FS 5.0111.34 ok 6.94/2.88 ok > /0/4.83 ok EAST RENTON/ROSEMONTE EARLY START TECHNICAL INFORMATION REPORT City of Renton, Washington Prepared For: Cam West Real Estate Development, Inc. 9720 NE 120th Place, Suite 100 Kirkland, WA 98034 Issued May 16, 2008 Revised June 25, 2008 Prepared By: Sheri Murata, PE Job #01-047 East Renton/Rosemonte -Early Start Technical Information Report TABLE OF CONTENTS I PROJECT OVERVIEW ......................................................................................................................... 1-1 2 CONDITIONS AND REQUIREMENTS SUMMARY ........................................................................ 2-1 2.1 CORE REQUIREMENTS ....................................................................................................... 2-1 3 OFFSITE ANALYSIS ............................................................................................................................. 3-1 4 FLOW CONTROL AND WATER QUALITY DESIGN ..................................................................... 4-1 S CONVEYANCE SYSTEM ANALYSIS & DESIGN ............................................................................ 5-2 6 SPECIAL REPORTS AND STUDIES ................................................................................................... 6-1 6.1 GEOTECHNICAL REPORTS .................................................................................................. 6-1 6.2 WETLAND DETERMINATION REPORT ................................................................................ 6-1 6.3 WETLAND RECHARGE ....................................................................................................... 6-l 7 OTHER PERMITS .................................................................................................................................. 7-1 8 TESC ANALYSIS, DESIGN AND CONSTRUCTION STORMWATER POLUTION PREVENTION PLAN ...................................................................................................................................... 8-1 8. l SEDIMENT POND ................................................................................................................ 8-l 8.2 SEDIMENT BASINS ............................................................................................................. 8-3 9 BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT ....... 9-1 9. l BOND QUANTITIES ............................................................................................................ 9-l 9.2 FACILITY SUMMARIES ....................................................................................................... 9-l 9.3 DECLARATION OF COVENANT ........................................................................................... 9-l 10 OPERATIONS AND MAINTENANCE .............................................................................................. 10-I Job #01-047 June 25, 2008 Page i East Renton/Rosemonte -Early Start Technical Information Report LIST OF SUPPLEMENTAL INFORMATION SECTION 1 TIR WORKSHEET SECTI0N3 LEVEL I DOWNSTREAM ANALYSIS REPORT SECTI0N6 EXISTING WETLAND TRIBUTARY AREA EXHIBIT EARLY GRADING WETLAND RECHARGE TRIBUTARY AREA EXHIBIT GEOTECHNICAL ENGINEERING REPORT FOR Rosemonte-East Renton Property, by ASSOCIATED EARTH SCIENCE, INC. dated November 12, 2007 Job #01-047 June 25, 2008 Page ii East Renton/Rosemonte -Early Start Technical Information Report 1 PROJECT OVERVIEW As part of the Early Start Grading Plans, this project proposes to only clear and grade the site and install temporary erosion and sediment control measures. No elements needing structural review such as walls will be constructed. In the future, this project will create 91 single-family lots including open space, sensitive areas, recreation and a detention tract on a 26.54 acre property. The site is bounded east by 148th Avenue Southeast and north by Southeast 1181h Street (if extend to the west). The site is bounded by parcel 1023059017 to the west and parcel 1023059368 to the south. The project is generally located wes_t of the intersection of 148th Avenue Southeast and Southeast !20th Street; Section I 0, Township 23 north, Range 5 east, W.M., King County, Washington. The Vicinity Map below shows the general location of the site. This Technical Information Report follows the 1998 King County Surface Water Design Manual (KCSWDM). Job #01-047 June 25, 2008 Vicili'ility Map NOTTO SCALE Page 1-1 East Renton/Rosemonte -Early Start Technical Information Report Currently the site consists of two existing single-family homes, a shop, a small covered storage building, and a gravel driveway ( all to be removed). A wetland area exists along the western portion of the site that will not be disturbed and set aside in Tract F and G. The existing site has one drainage basin that drain into Honey Dew Creek which, according to the December 1990 King County Sensitive Areas Map Folio, is an unclassified stream in the May Creek Sub-Basin. Honey Dew Creek combines with May Creek greater than two miles downstream (north) of the site. May Creek is in the Cedar River Drainage basin and ultimately discharges into Lake Washington. Refer to the Level 1 Downstream Analysis in Section 3, which was submitted on November 10, 2004, for a full description of the existing site and drainage patterns. Temporary erosion and sediment control (TESC) measures such as Clearing Limits, Cover Measures, Perimeter Protection, Traffic Area Stabilization, Sediment Retention, Surface Water Controls, and Dust Control will be implemented according to Best Management Practices (BMPs ). Job #01-047 June 25, 2008 Page 1-2 King County Department of Development and Environmental Services TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Project Owner: CamWest Real Estate Development. Inc. Address: 9 720 NE 12d" Place Suite 100 Kirkland. WA 98034 Phone: (4251 825-1955 Project Engineer: Sheri Murata. P.E. Company: Triad Associates Address/Phone: 425 821-8448 D Subdivison D Short Subdivision D Grading D Commercial X Other: Early Start D River D Stream D Critical Stream Reach D Depressions/Swales D Lake D Steep Slopes Project Name: East Renton/Rosemonte Location: Township: 23 N Range: 5E Section: 10 D DFWHPA D Shoreline Management D COE404 D Rockery D DOE Dam Safety D Structural Vaults D FEMA Floodplain D Other D COE Wetlands D Floodplain X Wetlands D Seeps/Springs D D D High Groundwater Table Groundwater Recharge Other Slow Slight Moderate Slow to Medium D Ch. 3 -Downstream Analysis D D D D D D Additional Sheets Attached MINIMUM ESC REQUIREMENTS DURING CONSTRUCTION X Sedimentation Facilities X Stabilized Construction Entrance X Perimeter Runoff Control X Clearing and Graing Restrictions X Cover Practices X Construction Sequence X Other LIMITATION/SITE CONSTRAINT MINIMUM ESC REQUIREMENTS AFTER CONSTRUCTION X Stabilize Exposed Surface X Remove and Restore Temporary ESC Facilities X Clean and Remove All Silt and Debris X Ensure Operation of Permanent Facilities X Flag Limits of SAO and open space preservation areas D Other :~1~;~; J;:1~:~t~it:~}f Jt:~~· ;;;;_ ;: .... , · ' I, X Grass Lined D Tank D Infiltration Method of Analysis Channel D D KCRTS Level 1 Vault Depression X Pipe System D Compensation/Mitigation Energy X Flow Dispersal of Eliminated Site D Open Channel Dissapator D Storage Waiver D Dry Pond D Wetland D Regional X Wet Pond D Stream Detention Brief Description of System Operation: Level 1 KCRTS detention pond with basic water quality wetpond. Facility Related Site Limitations Reference Facility Limitation D Cast in Place Vault D Retaining Wall D Rockery> 4' High D Structural on Steep Slope D Other D Drainage Easement D Access Easement D Native Growth Protection Easement D Tract D Other I or a civil engineer under my supervision my supervision have visited the site. Actual site conditions as observed were incorporated into this worksheet and the attachments. To the best of my knowledge the information provided here is accurate. [rµJ 91 mwt~ 7/11/og Sianed/Date East Renton/Rosemonte -Early Start Technical Information Report 2 CONIDITIONS AND REQUIREMENTS SUMMARY 2. 1 Core Requirements 2.1.1 Core Requirement #1: Discharge at the Natural Location The site has two drainage basins, one that generally drains towards the northwest and the other that drains to the west. A wetland occupies the western portion of the site where the two basins combine then flows to the north through Honey Dew (Honey) Creek. The site generally slopes to the west from 148th Ave SE down towards Honey Dew Creek at approximately 5-15%. One drainage facility is proposed for the entire site. The pond is to be located in the northeast comer of the site. Please refer to the Level I Downstream Analysis in Section 3 for a complete description of the discharge points of the site. 2.1.2 Core Requirement #2: Offsite Analysis Please see Section 3 -Level I Downstream Analysis. 2.1.3 Core Requirement #3: Flow Control Not applicable for the Early Start Plans 2.1.4 Core Requirement #4: Conveyance System Not applicable for the Early Start Plans 2.1.5 Core Requirement #5: Erosion and Sediment Control Please see Section 8 -TESC Analysis and Design. 2.1.6 Core Requirement #6: Operations and Maintenance The temporary drainage systems and facilities will be privately maintained, until permanent condition where the drainage systems and facilities will be publically maintained. 2.1.7 Core Requirement #7: Bonds and Liability Bond Quantity Work Sheets and Liability insurance will be provided at the end of the review process. Job #01-047 June 25, 2008 Page 2-1 East Renton/Rosemonte -Early Start Technical Information Report 2.1.8 Special Requirement #1: Other Adopted Area-Specific Requirements 2.1.8.1 Critical Drainage Areas Maps from the King Country Sensitive Areas Folio show that the site is not in a sensitive drainage area with regard to aquifer protection zones, seismic hazards, coal mine hazards, erosion hazards, landslide hazards, or the I 00-year floodplains. The 1990 King County Wetland Inventory did not list the wetland on this property. The existing wetland is located along the western portion of the site and is not to be disturbed with a 32.50' buffer. The 1987 Basin Reconnaissance Program did not list Honey Dew Creek in any of its basin reconnaissance data. Please see Section 3 -Offsite Analysis for a copy of the King County Sensitive Area Maps. 2.1.8.2 Master Drainage Plan Not applicable. 2.1.8.3 Basin Plans According to the King County Basin Reconnaissance Program, the site is located within the May Creek Sub-basin of the Cedar River Drainage Basin. Please see Section 3 -Offsite Analysis for a copy of the King County Basin Map. 2.1.8.4 Lake Management Plans Not applicable. 2.1.8.5 Shared Facility Drainage Plans Not applicable. 2.1.9 Special Requirement #2: Floodplain/Floodway Delineation Not applicable. 2.1.10 Special Requirement #3: Flood Protection Facilities Not applicable. Job #01-047 June 25, 2008 Page 2-2 East Renton/Rosemonte -Early Start Technical Information Report 2.1.11 Special Requirement #4: Source Controls Not applicable. This project is not a commercial, industrial, multifamily or a redevelopment of a commercial, industrial or multifamily project. 2.1.12 Special Requirement #5: Oil Control Not applicable. This project is not a commercial or industrial site. Job #01-047 June 25, 2008 Page 2-3 East Renton/Rosemonte -Early Start Technical Information Report 3 OFFSITIE ANALYSIS Please refer to the "CamWest -East Renton Level I Downstream Analysis" by Triad Associates, dated November 10, 2004, as submitted to the City of Renton. Job #01-047 June 25, 2008 /r.JMNJ ----· Page 3-1 ,.,/ Prepared By: CAMWEST = EAST RENTON Level 1 Downstream Analysis King County, Washington Prepared For: Cam West Real Estate Development, Inc. Issued September 19, 2002 Revised November l 0, 2004 GeoffE. Tamble, PE Tyson Wentz Reviewed By: Rebecca Cushman, PE . TABLE OF CONTENTS PROJECT OVERVIEW .............................................................................................................................. 3 GENERAL DESCRIPTION OF PROPOSAL. ...................................................................................................... 4 PREDEVELOPED CONDITION OF SITE ........................................................................................................... 4 DEVELOPED CONDITION OF SITE .............................................................................................................. , .. 4 0FFSITE STORMWATERRUNOFF ................................................................................................................. 5 DRAINAGE BASIN, SUBBASINS AND SITE CHARACTERISTICS ....................................................................... 5 OFF-SITE ANALYSIS ................................................................................................................................. 6 STIJDY AREA .............................................................................................................................................. 6 TASK I, STIJDY AREA DEFINffiON AND MAPS ............................................................................................ 6 Onslte Basin .......................................................................................................................................... 6 Upstream Basin ..................................................................................................................................... 6 TASK 2, RBsOURCE R.Evmw ....................................................................................................................... 7 TASK 3, FIE!D INSPECTION ......................................................................................................................... 7 TASK 4, DRAINAGE SYSTEM AND PROBLEM DESCRIPTION ......................................................................... 8 TASK 5, MffiGATION OF EXISTING AND POTENTIAL PROBLEMS .................................................................. 8 ( APPENDIX. ................................................................................................................................................... 9 ._J Preliminary Plat Map Existing Conditions Exhibit Developed Conditions Exhibit Soils Map Soils Legend Table 3.2.2B -Equivalence between SCS Soil Types and KCRTS Soil Types King County Drainage Basins (Figure 2) Study Area Maps (1990 King County Sensitive Areas Map Folio) Wetlands Streams and 100-Year Floodplains Erosion Hazard Areas Landslide Hazard Areas Seismic Hazard Areas Coal Mine Hazard Areas King County iMAP Drainage Complaints Maps Drainage Complaint List and Complaints Downstream Drainage Exhibit King County Off-Site Analysis Drainage Table TRIAD ASSOCIATES-LEVEL I REPORT FOR CAMWEST, EAST RENTON PAGE2 ( PROJECT OVERVIEW This section gives an overview of the project site in both the pre-developed and developed condition. There is also a description of the runoff characteristic of the property and the existing soil classification. The proposed project consists of a Single Family Residential Development for 66-lots on 15.92 acres in an R-6 zone. The site consists of two existing lots that total approximately 19.6± acres, with approximately 8.2± acres of sensitive areas to remain undeveloped that include a wetland (please reference Preliminary Plat Exhibit in Appendix). The proj eel is generally located west of the intersection of 148'h Ave SE and SE 1201h St. in King County; Section 10, Township 23 north, Range 5 east, W.M., Washington State. SITE ro 1-4 s N[ 4th ST I -& Vicinity Map NOT TO SCALE SE: 116th ST SE: II 7th ST PARK de RIDE TRIAD ASSOCIATES -LEVEL I REPORT FOR CAMWEST, EAST RENTON PAGE3 GENERAL DESCRIPTION OF PROPOSAL In general, this project will replace one existing single-family home, a shop, a small covered storage building, and a gravel driveway with 66 single-family lots. Part of the major site improvements will include the installation of neighborhood access streets (sub- collector, sub access, and minor access). 148'h Ave SE will be improved with full half street improvements as required by the King County conditions of approval (To be determined). All runoff from the site and the frontage improvements will be collected in the proposed conveyance system. Detention and water quality will be provided according to King County Standards. Two drainage facilities are proposed, one for each drainage basin. A vault is proposed to be located in the northwest corner of the site and a pond at the northeast corner of the proposed project of Rosemonte, adjacent to the north of E. Renton. The dimensions of the proposed lots and roadways will require buffer averaging on the western portion of the site. PREDEVELOPED CONDITION OF SITE The site contains an existing house, a shop, a small covered storage building, and a gravel driveway. The remainder of the site is covered with a mixture of pasture, blackberries, and trees (See the "Existing Conditions Exhibit" located in the Appendix). The site has two drainage basins, one that generally drains towards the northwest and the other that drains to the west. A wetland occupies the western portion of the site where the two basins combine then flows to the north through Honey Dew (Honey) Creek. Overall, the site slopes from east to west at approximately 5-15%. The site generally slopes from 148 1h Ave SE down to the west towards Honey Dew Creek. DEVELOPED CONDITION OF SITE The developed site improvements will be located on the eastern 15 .92 acres of the property (See the Developed Conditions Exhibit located in the Appendix). The preliminary plan shows 66 single-family lots with subcollector, sub-access and minor access roadway improvements. 1481h Ave SE will be improved with full half street improvements as required by the King County conditions of approval (To be determined). The detention/water quality facilities will be designed to meet the Level I Detention TRIAD ASSOCIATES-LEVEL I REPORT FOR CAMWEST, EAST RENTON PAGE4 .Standards and the Basic Water Quality Menu from the 1998 King County Surface Water Design Manual. 0FFS1TE STORMW ATER RUNOFF Flows entering the site from the east come from the west half of I 48 1h Ave SE. Runoff entering the site from the west and south adjacent to the wetland is collected in the wetland area. The wetland area will remain undeveloped. Runoff generally does not enter the site along the north and south property lines near the proposed lots since the site slopes from east to west. DRAINAGE llJASIN, SUBBASINS AND SITE CHARACTERISTICS The existing site has two drainage basins that drain into Honey Dew (Honey) Creek which, according to the December 1990 King County Sensitive Areas Map Folio, is an unclassified stream in the May Creek Sub-Basin. Honey Dew Creek combines with May Creek over two miles downstream (north) of the site. May Creek is in the Cedar River ( Drainage basin and ultimately discharges into Lake Washington . .::.__/ The site contains an existing house, a shop, a small covered storage building, and a gravel driveway. The remainder of the site is covered with a mixture of pasture, blackberries, and trees. Most of the trees are located in the western half of the site with the pasture area occupying the eastern portion. The blackberries are located throughout the property. According to the King County Soil Survey, refer to the Soils Map and Legend in the Appendix. The site is underlain with AgC (Alderwood gravelly sandy loam, 0 to 6 percent slopes) and AgB (Alderwood gravelly sandy loam, 6 to 15 percent slopes) soils belonging to the S.C.S. type 'C' hydrologic group or 'Till Soils'. Onsite topography is mild to moderate, sloping to the west at approximately 5% to 15%. Note: The 1990 King County Wetland Inventory did not list the wetland on this property. The 1987 Basin Reconnaissance Program did not list Honey Dew (Honey) Creek in any of its basin reconnaissance data. TRIAD ASSOCIATES-LEVEL I REPORT FOR CAMWEST, EAST RENTON PAGE5 OFF-SITE ANALYSIS This section outlines the drainage basin, within which this project is located, highlighting the downstream conditions one mile from the project site. STUDY AREA TASK 1, STUDY AREA DEFINITION AND MAPS This site is located within the May Creek Sub-Basin of the Cedar River Basin. Onslte Basin The site contains an existing house, a shop, a small covered storage building, and a gravel driveway. The remainder of the site is covered with a mixture of pasture, blackberries, and trees. Most of the trees are located in the western half of the site with the pasture area occupying the eastern portion. The blackberries are located throughout the property. According to the King County Soil Survey, refer to the Soils Map and Legend in the Appendix. The site is underlain with AgC (Alderwood gravelly sandy loam, 0 to 6 percent slopes) and AgB (Alderwood gravelly sandy loam, 6 to 15 percent slopes) soils belonging to the S.C.S. type 'C' hydrologic group or 'Till Soils'. Onsite topography is mild to moderate, sloping to the west at approximately 5% to 15%. Upstream Basin Approximately half of 148 1h Ave SE along the entire site frontage currently sheet flows into the site. Flows from the frontage improvements will be collected and conveyed to the proposed detention/water quality facility. The area where flows enter the site from the south and west adjacent to the wetland will remain undeveloped. TRIAD ASSOCIATES-LEVEL I DOWNSTREAM ANALYSIS FOR CAMWEST, EAST RENTON PAGE6 l_1 TASK 2, RESOURCE REVIEW / I "1998 King County Surface Water Design Manual" "1990 King County Sensitive Areas Map Folio" "1973 King County Soil Survey'' There are no apparent problems associated with this project. 1l' ASK 3, IFIELD INSPECTION "Triad Associates" preformed a field visit on 4/03/01 to locate any potential problems upstream or downstream of the proposed development. The weather was overcast and approximately 55 degrees with small amounts of runoff in the drainage systems from the previous day's rainfall. See the "Downstream Drainage Exhibit and Table" located in the appendix for a complete definition of the Study Area. Drainage leaving this property is collected in an existing wetland (A) and conveyed offsite to the north through two 12" CMP culverts (BI & B2). The onsite wetland has a slight ridge separating the wetland on the north property line of the site. The runoff that leaves the through the two 12" CMP culverts combines in a drainage ditch adjacent to the north property line (C). Drainage also leaves the site on the north east side (C2) then drains west and intersects with the drainage from CI . From here the runoff flows to the north through a natural drainage course called Honey Dew (Honey) Creek (D) for about 500' before entering a 24" CMP private driveway culvert (E). The property owner adjacent to the culvert stated that it has only flooded once, around 15-years ago, when a neighbor downstream of their property dammed up the creek to make a waterfall. The waterfall has been removed and the culvert has not flooded since that time. From this culvert, the natural drainage course continues to the north in a well-defined channel with heavy ground cover (F). The final observation of the downstream investigation was approximately 2000' downstream of the site (G). No evidence of flooding or major erosion was observed along the downstream drainage course during the site visit. From the last observed point in Honey Dew (Honey) Creek (G), runoff continues north then west before combining with May Creek and eventually reaching Lake Washington about _., 6 miles to the West. TRIAD ASSOCIATES -LEVEL I DOWNSTREAM ANALYSIS FOR CAMWEST, EAST RENTON PAGE7 ( J '-- TASK 4, DRAINAGE SYSTEM AND PROBLEM DESCRIPTION "King County Water and Land Resources (WLR) Division Drainage Complaints" King County suggests not following up on any complaints before 1990 due to their age and development that has occurred. Complaints Nos. 94-1000, 95-009, 96-0185 and 96-552 all pertain to one parcel (9353). The majority of the complaints pertain mostly with drainage runoff from 148th Ave SE. In particular, an existing ditch was discharging into this property and flooding the basement. King County performed a study of the situation under the Neighborhood Drainage Assistance Program (NDAP) and recommended the installation of a catch basin with a 12" conveyance system to direct the flows away from the home. This project was not completed by the County; however, the home owner installed a similar pipe system as recommended by the County prior to February of 1996. Therefore, the NDAP study was cancelled. Complaint #96-0552 was due to a broken fire hydrant (vandalism), not stormwater, and therefore closed. Additional complaints are within the I mile radius of the project site but are not in the c..../ downstream drainage path. The complaints are linked to a private home drainage system and a private road washout due to no drainage system rather than flooding, or erosion of the large drainage course that the site will discharge to. TASIK 5, MITIGATION OF EXISTING AND POTENTIAL PROBLEMS The developed site runoff will be detained ·10 the Level I standard as outlined in the King County Surface Water Design Manual -1998. The KCRTS Level I detention standard requires maintaining the high flows at their pre-development levels for all flows greater than the 2-year peak flow up to the 10-year peak flow. The site is proposing to utilize two detention systems. The detention facility release rates will be based on the existing runoff from the area of the site that is being developed. The wetland area and associated buffers will remain undeveloped. One half of 148 1h A VE SE frontage will be picked up in the conveyance system along the site frontage reducing flooding discussed in the drainage complaints. TRIAD ASSOCIATES-LEVEL I DOWNSTREAM ANALYSIS FOR CAMWEST, EAST RENTON PAGE 8 ( '-/ APPENDIX TRIAD ASSOCIATES-LEVEL I DOWNSTREAM ANALYSIS FOR CAMWEST, EAST RENTON PAGE 9 -NOV. 8. 2004 rn: 32RM KC WLRD ~ ' ·?' \ ,,..., rr' -41. . .. · NO. 339 .• P. 4/20 I """""-KING COUNTY .SURFACE WATER MANAGEMENT DIVISION DRAINAGE INVESTIGATION REPORT Paga 1; INVESTIGATION .REQUEST Type __ (!,_ ·' --· ! .. fi':~-rc.-,r;c_.,. __ o_at~: /..?;&?:: ll-OK'~ b~~-..:;fti F~'.:f(-;o 00 __ ?eoBived from: (Please print plainly for acannlnQI. (Day) (l!ve) ~ME: )v t>Y! #er2=-6 e-"712.., PHONE £..fS~ '1? ,f S. ___ _ >DRESS:. / /& / 5° /fl../4 #ra---Sc City £z.,-; ~,..J State Zip fg' OS~ ,cation of problem, ~ different: -----------------------------,ported Problem: it name: her agencies Involved; Basin /'it II-'( Councn Dist Charge No; 'POSITION: Turned toiJ!.._ on A· 10-7![ by ::!!1 • Lead agency has been notlfled: Lot No: Kroll __ _ Block No: The Bros; New 1P-7 /?] o1d ss.EA .. OR: No further action recommended because: Problem has been corrected. --TlN,_o-p-ro.,.bl,..e-m"'h-as__,..be_e_n.,.,d.,..e...,nt""ttl,...ed.,., -----,P""rt.,..o-r ,..lnv-e-st""'lg_a.,,.tlo_n_a-d""dr-a-ss_e_s -pr""'oblem: -Sao Ale# · ' ts problem -NDAP will nor consider because: ~ Water originates onslta and/or on neighboring parcel _ Location Is o~slde $WM Servloe Arna. _ Other (Specify): ~TE CLOSl!D; ..!;.J :2-t.; _tt" by: ~ ~ • ~ NO'v. 8. 2004 10: 33At1 KC WLRD ~ ... , .... ,_ ____ ..,.... ...... ~ ..... ( KING COUNTY SURFACE WAT~R MANAGEMENT DIVISION DRAINAGE INVESTIG.A.TION REPORT , of Investigation: "1PLA.INT 1194-1000 METZGER :stlgated 1-6-95 by Doug Dobkins Page 2: FIELD INVESTIGATION It with l',i{rs, Metzger oDBite to discuss her dnunage concerns that flooded the basement of her house. N0.339 basement WB& flooded and damaged three rooms and a bathroom. Metzger lives below road grade and reeieves water from 148th ave md also a dltoh to the north of her properfy that ls aimed right at her liouse. She has a small yard drain in the norteast comer of her lot tries to halldle this tlowlt appears the small yard drain couldn't handle the l'.low of water and overtopped·and flooded the basewnt, 1 roadside ditch has waler contrlbUICd by three properties to the north of Metzger that drains into thl• ditch. Mrs. M,eb:ger wnnts to know , ls responsible for thls drainage alld who can fix the problem .. .... ··. ·····.::\:.: .. >· ... \'.~ . ...... _v,:,;;·;"""':~\\',, ~-( ~ ~-;-.-----, ---------------~~· Al' !se 116th s1, I --- ~ --~--~~" 1411111 A VB SB Investigated by _____ ~-------Date. ______ _ NOV. B.200~ 10:33AM KC WLRD ( . project Na111e: . . ' NDAP PIU:oR!TY SCORING .. k,w. J\14,f.z~e.'e Project Number: w *********II'************** *IMPACT CRITERIA***********************·***.:,;,, EOiliT!;l-ADQ o,~ iPROEEBTIE;S FU'.:!:, B:1:SK IMPACT OR 4 FOR SEVERITY !MPAC'!;'ED (+0 1 2 OR 4) L.i V ing s t;t'UCtUr/a,' · ..12._) _j_ :finished floor (20 + X + _Q_ "' Access (8 + _) X + "" '° .. Septic/Well (8 + ___ :_J X + "" 0 Other structure or (4 + _) X +· Q crawlspaoe ...z.. __.cL r2 Landscaping/yard/. (1· + ~) X + = parlcing Other property/ (. 5 + -12.:__) X __Q_ + ...Jj_ = 0 dr.ainage system Natural resource 3 + ··+ = 6 ;' i . *********************EVENT FREQUENCY FACTOR************************ ·, ( ) < Chronic (l+ times/year) ..... 20 2-5 years; indefinite but · o.ften; channel erosion, . . • 10 5-10 years ................. . 10-25 years ....••. ~·······-· 5 2 E.F,F. = . /() SUBTOTAL XE. F. F. = . .f1t;Jl'if; ADD 20 POINTS IF IN A TARGIE'l'ED BASIN + --=O._ >25 years •.••..•••.•....... , 1 TOTAL-lMPACT SCORE= Date: 3/J(l Jw Rated by A.EM · niA'4 . I ·~ . **** *** ***** ********* *****COST-BENEFIT RATIO***********'************ · ·cosrr OF sotUTroN = $ / ~ 2, JP ,7 'lt:f tf Ar,1 TOTAL IMPACT SCORE X 100 / COST = NPAl' PRIORITY sooaE c: t 2d Date: z/14,1,r. . Ra 7ect by * Not!!: F ving spec.~ from storms <: 10 years r~caivas top ority. Yes. --------==~==-:so== .... =-::.:::: .. --..... _,_ --·-·-...... _ ............. -·-·-· .. ~~~· i=sN"' .. ?,alY-. ./..8_.~ _2""01..0-_1_-_'.0.Lj ·_3-_3L~_~__;.1_. _-·lr_c_ .. w:t~R~"D[a(.~J-t~~-~·~1-~~-~::.1::.:•··~·t'~J::. :: .. -l...J. . .:':" ,L-_ .. ::;· r.;.·:..·· J .. !_. ·:.··~·;-_:-_:·ti..: ... :.::NLO_ .. 3j3_9~· .. _ .. _p~1·_7_/,_20 .... , : ......_._--.:._;__, ( ( DATE: 3-l5-95 ,. NEIGHBORHOOD 01\AINAOE ASSISTANCE PROGRAM COMPLAINT EVALOATION MEMO TO: RANDY SNOW FRO!,!: A!,AN, MEYERS RE: NDAP £VALUATION FOR COMPLAINT NO, 94-1000 KI!,! METZGER BI\Cl\GROUNO I The original complaint was called in on 12-29-94 and Doug D, completed the initial field investigation on 1-6-95. Randy Snow and I spoke to both Mss, MetzgeJ.' and Schi;oeder during ouJ.' field evaluation .on 3-6-95 on Surface water from BtraetB, pastures ilncl rude north and east Of Met:ger•s property which acoumulate and f ow into a very niuerow drainage ditoh within the 148th Avenue SB R/W flowing south along the west aide of 146th into the NE corner of Metzger'e yat:d which is a low point below ·road grade in this neighborhood basin, The flow partially drains into a private OB at the NB corner of her ya.rel which conveys some water through an 8 inch buried CPP pipe west aroµnd the no~ aide of bar house and discharges west into the Schroader·• s horse paature(see complaint 95- 0009) approximately 6 feat lower than Metzger'a back yard Level. A small pond forms at the Nl!l corner of Metzger'& yard and during recent heavy runoff flooded into her basement filling eeveraL bedrooms and a bathroom, damaging furniture, carpets and walls. The Schroeder's complaint includes reported erosion, sedimentation, and ~ncreaaed mi.nor flooding across their large slopin~ horse yard/pasture from NB to SW towards a low wooded area which clevelope into the upper channel of Honey creek which ia tributary of May Creek, For this report, the horse pasture area impacts are considered to 111\paot a horse boarding coi:nmercial buainesa. fINDINGS& Since the problem meets all of the NDAl' project criteria listed below, it qualifiee for and has been investigated under the NDAP program, • • 0 • The problem site is within the SWM earviae area and does not involve a King county (RO) code violation. The problem site shows evidence of or reported localized flooding, erosion and/or eadimentation within the off road drainage ay~tem on private residential and/or com111ercial property due to Later upstream clsvalopment (Property other than RO or State roads, parks or schools), The problem ie caused by surface water (not groundwater) from mOJ.'a than one adjoining property and creates impacts beyond the property owners• control, If there ia only one affected property, that property oontril:>utea leas l>han 7SI of the peoble~ runoff, ~ ~hiB project has top prioritr rating under the llllAl' because flooding of livu,g opace has ooourred fro• a atorm judged to ba less than a 10 rear atot'III avant, PAGE 1 OF 3 ( NOV, 8.2004 10'34RM KC WLRD N0.339 -----------...------···-~- orTIONS AND DISOUSSlON Options coneidered to convey the excess surface storm water past both properties include the following, •\ 1, Inatall an underground 12 inch storm drain eyatem from the NE corner of the Metzger•e yard near the existing CB 1 weat approximately 130 lineal feet to just ineide the Schroeder's property line, 'two Type 1 CBe woula be installed, one at each end of this 12 pipe. From the outl"t of the second OB to ba located near the Nl!l corner cf the Schroeder• s horse yard· on the south aide of the CB,. a. scour protection rip rap outlet would convey the storm water ea.fely into a. grasaed earthen swale a.bout 8 feet wide which would run approximately 175 feet · south along the Schroeder' e east property line where it would discharge .l.nto an exieting ditch line flowing east to west down into what appears to be a natural drainage channel which flows west-northwest. This storm water ewe.le would include a scour protection structure/facility located at the outlet of the storm drain pipe in the SE corner of the horse yard in order to aafelr·convey the peak flows from the end of the grassed swale into the ex sting east-west man-made ditch, 2. Thie option is similar to No. 1 described al:>ove, The difference ie that the conveyance facility from the NE corner of Metzger•e yard west to the Sehroedt,r•e NR corner would eoneist of a graea lined awale in place of the 12 inch storm drain pipe. Thia option would include a U shaped discharge chute made with several rock gabion/Reno mattresses aet on a layer of heavy duty filter fabric located at the end of the swale at the west side of Metzger's back yard. Thie chute would provide soil erosional protection where the storm runoff would discharge from the upper awale down into the awale to be located along the east aide of the Schroeder's horse ya.rd. From thia point, the storm water would be conveyed south approximately 175 feet as described above in Option No. 1. IHPAC~ SCORE~ 220 PRQPOSl!lJ> SQLOTION1 Since the safe conveys.nee of the peak storm r,,noff through the Met2ger•e yard is. of primary importanea, I recommend Option No. 1 be employed tc safely convey the peak storm water flows pa.et the Mstzger'e house. sinoe a grassed swa.l.e might erode or waab out and fail resulting in another basement flooding event, the storm dl.'ain faoility included in ·Option No, 1 is preferred based on reliability IUld safety. ·sowevar, there is a question whether or not a !i'ype l CB and 12 drain pipe would have tbe capacity to adequately protect the Met~ger•e yard and home, A small basin study was complated in order to verify the size of storm drain facility required. The results of the study using the seua computer model were as ehown below: Baaio Data From Maps and the Basin Area 26?R-2411R Preoip. To Soil Type Areas and ONe1 KCSWM Design Manual, 3.6 Acres 3,5 Inohea 24,0 Mimatae Alderwood Croup C Pervioua Area. 75 "' of Area Aliea in aorea ON Impervious Area 26 2,7 0,9 B6 98 PAGll 2 or 3 .! l<C WLRD N0.339 RESl1L!l!S OP' !!!Ill! SBUII ME!l!UOD BASIN ANALYSIS P'OR 25 YEAR STORM: .. , ,. PEAK Q OPS !!!~PEAK !IRS V0Ii0'MB CP' l.70 7,83 31,065, Based on a deeign peak flow of 1,7 CFS, a 12 inch concrete storm drain pipe at a 21 elope would have an ample capacity of 5.5 CFS. However, since thEI maximum oepaoity of a norma-r Type 1 CB grate inlet equale only about 1 CFS, an expanded grate or cone type reber inlet structure would be required along with a below 91"ade rim inlet set in a depression as well as a raised masonry type semi-circle wing wall around the CB inlet to help ocnfina and direat the peak flows down into the oe inlet. A grassed earthen emergency overflow swale would also be required to convey peak flows exceeding the design peak flow of 1.7 CFS around the house. This project is estimated to cost approximately$ 11,200, The feasibility of thie project includes the follow-ing limitations: l, The clearanoe on the nbrth aide of the Meteger'e house is tight and will probably slow oonstruotion work along the north property line. Acceae to the backyard will require temporarily r~moving a portion of a 4 foot high fence in two locations for equipment and installation of the storm drain along the north property line, 2. Utility conflicts along the north property line are unknown except the exieting 6 or 8 inch OPP drain pipe shown on the field investigation repo>:t. Other utilities could be in the yard areas? 3. the horse sensitive owners as Construction in both yards may be limited by poor aoila and yard operations including breeding/foaling,eeason or other horse iaeuea. The project must be coordinated with both requirecl PRIORITY SCORE: 1,96 FII.1! llDIIBVJll.,DOO lN WORD 6,0 AEK 3-7•? PAGE 3 OP' 3 ... ·····-·-·· NO'I. 8.2004 t" '( N0.339 10 :34AM KC WLRD mer~vmv·ta1~·k:..i-e· tv~ -i-sR M~NAGEMENT ·~,~1s10~ DRAINAGE INVESTIGATION REPORT f'a.Qll 2: FIELD INVESTIGATION P. 10/20 .---:--------,-------------·-----------------,---- :a,alls of ln"VB$tigaf/on: ''· COMPLA.1NT #95--0009 schroeder tnvestigated l-<i•95 by Doug Dobkins Meet with MI,. Metzger onsite to discuss henlminagc concerns that flooded the basement 'of her house. The basement was flooded and danuu,cd three rooms and a batllroom. Metzger lives below road grade !ll1d recieves water from 148th ave SB and also a ditch to the 11orth of her property that is aln\ed rlght at her house. She has a small yard drain In the norleaSt corner of her Joi that tries to hudle th1s :flow.rt appoars the small yard drain couldn't handle the :flow of water and overtopped and flooded tbe b~ment This roadside ditch bas water contributed tly tllroe properties to the north ofM<:ttger that drains into this ditch. Mrs. Metzger \V!lllts to kno· who Is responsible for tllls drainage and wbo can fix the problem. This lllso affecting the down stream neighbor of Metzger, Raymond iobroedet. c,:,mpl.aint number 95--0009. I called Mr .. Schroeder e.nd explained that thls would be looke<l at under the NDA roview on .<etiser complaint and wo close hls file to Metzger . Investigated by --- ... • .. ···· .. :;~>·· .. \, \ ti \~\\, \ \. ······-v:::.,·;·:·········.T . ~ lse 116th ST I />1 u.,.,., r ( Wit JI a. ro ?4 k J lli""~--J,..iitj;;jiii!u ~)( ,'.$f: e:~ --------------Date ______ _ ) ,.I L NOV. 8.2004 10:35AM KC WLRD N0.339 --KING COUNTY SURFACE WATER MANAGEMENT DIVISION DRAINAGE INVESTIGATION REPORT P. ll/20 ( . .· ~ecelved by: .f J., l'age 1: INVESTIGATION'FIEQUEST ----·-Date: !/:5 /'?S OK'd by: =114 iype ~ PllaNo,95-~ / Rscoivsd from: (Ploaso print plainly for scanning). (Day) .. --.. . ... -~ (!:voi·'~ .. NAME: .Schroeder. ' ADDRESS: l'/70/ :5£ /ca.Y/Hond J/1 771 ;5r PHONE 2. 77-6 J 3?, -Mori-'<l~ . ~ City !fec,1ror/ State Zip "" ~ Location of problem, If different: Report€1d Problem: Plat name: -~~ LJJ:der ,.s dra,,'n/17.9 ~rn Me street- +Anl his ne/ghoors /or erocU':5 h,s pr~ He. h>..S owned +his horn«. A;,r 2. years r. -,he. 1>rn'<:>le.n-1 o.-dy Oc.c.u.r.s c).v,r,n3 hecavy r""'-in fc.. II. C o..r, o-n \I i+'s i r-,_g-b""-c:l.o V) e +c . ..., G-lOP +\,,e. ~s,on · Lot No: Block No: Basin MR t Council Dist 12.. Charge No: ·~ ~ ~~ r.._,:(( ~ . . t.. 0/SPOS/TION: TUmed to ___ on ____ by~-- Lead agency has been notmoo: -Problem has been corrected. -_-""N_o_p_ro.,..bi'"'em:'"'."":C'ha,..,s.,.,b~ee""n.,.,lclr-en-.,tli"'"1ec1-.-. -----.P,...rl.,..o-r-.,,ln-ve"'s-::tlg--.a-::tl~on~ad,-;d-re-ssGs;:;;:- -Se• PIie # • ~·vbie1 Private problem -NDAP w/11 not consider b11oause: • · Water ol1glnates onslte and/or on neighboring parcel . = Location Is outside SWM~arvlo Ar . _ Other (Specify): . bATI: CLOSED: .Qj_; t..-5 JfS' by: f~9~-/~dg Nl)V, tJ.c'.lolo4 10:3sAMQO.KC WLRDJ!..L Yv.L.L>lCl)\l'!l.\. av'~.:.:-,..:,... ~-;:;,"N0.339 ~fr'\lf"'I ... ,..., 0 • ·-· (, a of lnvsstlgatlon: KING COUNTY SURFACE WATER MANAGEMENT DIVISION DRAINAGE INVESTIGATION REPORT Page 2: FIELD INVESTIGATION >:Ml'LAJ:NT #95.0009 schroeder ...st.I.gated 1-6-95 by Doug D_obklns :ct withMrii. Metzger onslte to discuss her drainage concerns that 1looded the basement ·other house. s basement was flooded and damaged three rooms and a bathroom. Metzger llvos below road grade and reciel'es· water from 148th a\'e and also a ditch to the north-of her property that is aimed right at her house. She has a small yard drain in the norteast comer of her lot t tries to handle thls tlow,rt appears the small yard drain couldn't handle the flow of water and ovcrtopped and flooded the ba=nt, Is roadside ditch has water QQl\trlbuted by three properties to the north ofMetzger that drains into this dltoh. Mrs. Metzger wants to know o is respon&ible fur this drainage and who can fix the problem. This also affecting the down stream neighbor of Metzger, Raymond u:oeder. complaint number 9S--0009. I called Mr~Schroedcr and oxplniru:d lhnt this would be looked at under tho NDA review. on !Z~ complaint and we close his file to Metzger. ( ·· .... ···-.:::;;;-\ \\ \\\ •. ;q'• \ ...... ...... -... :-,;::·:···"···-.\ - 148THAVB SB Investigated by ____________ _ !se 116lli ST I • Date. _____ ......-- -~ ,.L,(-tot·'l~ N0.339 P.13/2@ ---KING COUNTY SURFACE WATER MANAGEMENT DIVISION ( DRAINAGE INVESTIGATION REPORT· l I Page 1: INVESTIGATION "REOUEST. Type C__. "Re~~~-ed. by:. J, j_. --· --···. ----···-··· •.• Date: ·2-8-?f ____ ;~'d by: .•. ~ ···-·-File _No .. 9 l, _ CJ__l_8_~ Received from: (Ple~sa print plairdy !or ::.e.annino). (Doy) !Eve! NAME: Oave :Jbhason RHONE 25:3-2086 ___ _ :.ADDR:SS: . llb2 5 ./t./8,h·/it/£_ .5£ Cily. feJ?-ht1 Stato Zip7il:rQ.5 -,~:.·~· ,-,-.~.. ' .. ··' ~-... -. ' . . . . . . . :,~cation or prob1~m. ~ ditt~rant,---~";:,--;,·:·· ati . ;je,r' hb,:;r ){;n. ~h:-~· .:?3S~7{5'S -~-·------------·-. --.·--····--·---!fo-------------.--------~--····-····---····------ . Roporteri Probl11m: . .. o..+ /161&" /Pe Aus s~ l>P ;funcJ/f ·~m Jl~s .6.al'/7 on /«8.rt,Av / 5 Pl c10,:://n __f -J--hc: . JJ I-;"/? Son j and fne-hXu-s ,17r~p-!y, 7h~ (!u/verl .:;;n ;L/-8""(1'\. 'All[ SC /Jff[)S W BE ., . tn /arJed;,- Fli.t :ie.r.12: • Otha_r e.ganctes, l~wolvtd: .. : " Lo;. No: 31ock No:· No r'iald lnvestiga~lotl f\.'~edad __ _ 7h.a,os: N~,.-{p2t;;J" o:d uZ.7 A.. Basin ,YJll,q '( Cou11c~~~'.st ,~~:_C~he.::_rg'.'._'.e:_:N.:_:'o:::: ·::::::===:.:....,. __ _ ~BDL}-1e.Lf, DISPOS/7'/0N_: Turned lo ___ on ----Or\: No further action recomr:,er,d.xl ~a, ·f{/, lead e gency has been n'o1lfled: ·-...o.~~=~Uttt!.4::..__-14-~:__;Z....::::_· -:::-,--,--,--...;-~-.,.,....::._; ;;:.···.:..:· _. \~, Problem has been correct9d, ?rlor invos1loa1lo,, addresses pro -s.. Filt f • . .. ·. ~ PtiVP.re problem. NDAI' w/1/ nor oonsicfer bece~$8; . . Water oMglnates orislte ~nd/or on neighboring parcel . . = Locat\o~ t.s outside SWl,I s~. Pjes. ·. . _ Other (Spectf')•): o.:..TE CLOSED: -!:-I ft; 9 (,. b\~ .....l!:Yf ~ rf)r() /f'_Qf' . NOV. 8. 2004 , 10: _36AM KC WLRD ·NO. 339 .· P .14/20 ~'::.s..¥ ~-~~,~,~~11~1¥~h~1IH~ttr~11«~·~xp~, ......... =·~ .... ~~w·~n • .-._.....,._~ ·· ,,;.,;q4'N:••zr ···-··---------- ( COMPLAINT 96-0185 JOHNSON, DAVE: Investigated by Doug Dobkins on 2-21-96 Mr. John~g_n was not present at the time of investrgation. I left a door hanger with card and phone#. Mr. Johnson is concerned about the runoff from 148th . avenue SE flooding his property and the neighbor to the north of his property Metzgers. There Is a catchbasln at the northeast comer of SE 118th and 148th . Ave SE which backed up during the storm on February 8th. The pipe under 14Bth could not handle the capacity and backed up onto 148th and ran to the west onto Johnson's property and on Metzger's property. This problem looks to be created by the Intense storm on February 8th. I will call Mr. Johnson to find out whether the W&1ter backed up from the catchbasln or bypassed the basin and ran·down the driveway. NOA project'on the neighboring property of Metzger. Both live below road grade. LEFT MESSAGE WITH DAVE JOHNSON ON 2-26-96 SE 116TH ST OP!N DrTCH . 148TH AVE SE NUV. ci. ilJ04 / ( , 10: 36RM KC WLRD Type m.339 KINC'a COUNJY'SURFACE WATER MANAGEMENT DIVISION DRAINAGE' INVESTIGATION REPORT Page 1: INVESTIGATION REQU,EST /I ,f A) Date: j..-Z.3-q6 OK'd by: -frJ FIie No. q(j)-55 2..... ... Ad by: J. L. eoeived from: (Pleas. print plainly to, BCannlng). ME: £~y1r1on d 1 DRESS: / /6, I 5 I L/8 Tl-, :atlon of problem, ~ different; ,orted Problem: t name: 1er agencies Involved: T,'«-7 AV£ r:'la:;)de,d r()adwa-y, cla.,'r'VI. Parcel No. Basin f'n/.1 \(' Counoll Dist -~~· .• . (Day) (B,o) PHONE 23:i-978:S-_____ State __ Zip '18059" !f.Ja.-f--u-~,..,., · .be ?;·; rr;3 ~ Lot No: Block No: No Field Investigation Needed __ _ dntt1<1") Th.Bros: New(p2fe ;:]'(4 Old ~2-1 A,{p ~5.D3) J:='.3 'PONSE: Citizen notified on J(2j<, by hone _ letter _ in perso·n POSITION: Turned to~ on 3 iff1~ by~ OR: No further action recommended because: • Lead agency has been notified: --~-..,.,..--.-.,..;..--.~,,,,..-,-----=-...-,--...,,.-,.,.-..,...--- • Problem has been corrected. _ No problem has been ldentlfled. _ Prior Investigation addresses problem: '· is prob/&m -NC/AP WIii not conslrier becaus&: _ Water originates onslte and/or on neighboring parcel Location Is outside SWM Service Area. Sae File~·---------... k Other (Specify): lTE CLO.SEO: ....i.J-1J4h by:~ . ~~..1/kldi~ _ J-,~\M. t~ ~~o-«" NOV, 8.2004 P. 16/20' .. ,,.-....... ~ .. --·. ( Date: March 71 1996 l>ate of Jnw9tlgatiom March· 6 1 1996 FM: Gazy..Paul Reinko REI ll:valuation for Complaint#' 96--0552 Tim Raymond 1Lynn Metzker 11615 148th Avenue SE Renton. WA. 980S9 Dqy P 235•9783 )4s. Melzbr's home lies below the road olovation of 148th SE. She Btated that during the heiivy rainfalls otFebiuary, 1996, she experienced water Inside the house. Two bru.:ment living rooms were dam#god. . The carpets had to be replaced qnd the walls repainted. . Ms. Metzker llllld the water Is flowing from SE 116th Street.. over tho property to the north and also down a culvert In the ft'ont of the p1oj>ertY to the north. The culvert water flows Into a ca in the DOilheast corner of her propor1Y and then outtillls next the the l>cdro9m windows. Thia has happened at least once a year In the four yeus she has owned the prope11y, She was not aware otlhe:wateI problems when she bought the home. ' She Cocls that waw ls comlng down the ~ (148th) ftom some recent development. I recommerul th.at this be rumed over the the NDA Program lbr mther study, l~ '(\ ~tl.C, = i ,~--···-····" __ __,;.,~;::::.:.~-~~~;.;.E:-:. _______ _ . ·-··"'··---"--·----------1' ' !Bf}· 8.2004-10=35f;lM . ~ KC WLRD:w,:;,,=' ~··(OpttonwJ «: '·Z : -:z . . . · '{ r f i ! t l ·. · ; ·. · : . : . ,,, .. ;ae ·. ',(); ..... Date: March 26, 1!196 FM: Jeff Jncobson Neighborhood Drainage &slllt1lllce l'rogrlllll Complaint Evaluation Mmno RE: NDAP Evaluation for CompJA.int # 9G-OSS2 Tim Raymond/ Lynn Metzker U61S 148th Avenue SB Reolon, WA 980S9 Day P 235•9185 Complaint Chroool9gy Original: Field Inwst: FleldEval: Old Files: Btltkgrg\l!d 2·23·96 3-07-96 3-2S-96; 4-02-96 94-1000, 95-0009 1 .. TJm Raymond, the. complalnnnt, called Fobrwuy 23, 1996. The house slm S to 10 :feet below the Slllfaco ! of 148th Avenue SE. He·says runofi'from the roadway 120 feet to the north(SE 116th Street) ls tJooding hl5 basernCQt. 'l'hls road ls not maintained by the county. This has been a rc-<>oourring problem for hlm ewr since ho bought tho house. Mr. Raymond is the first owner Of tho house: He claims this son of floodl.llg ocours 1bur or five times a year. '·· Lynn l'dct2l=, tho current occupant oflhe house. had called in II complaint December of ·1994. The investigation was tllnled Into a NDA review. The NDA revlaw mu g1wn a top priority IICOre. However, bllfbxe any COIIStnlctlOII took place the owner of the house had installed a calllll buln/conveyance system ofhls own. The system installed by the owner was veiy similar to the system·recomincnded by the county. Therefore, the C01lllly elected to cancel the construction of the proposed ND A-funded conveyance system. llndlnn JJutlllg 'AfY site~ on April 3, 1996 I held a conversation with Mr. Clerspaoh. Mr. Oerspaoh is . the property Cl\\'llet ab11Uing Ms. Malzker/Mr. ~ond to the north. He clahns he a,q,erienoe<I sonie minor flooding on Pcbruuy 22, 1996 • .Apparently, some vandals bad destroyed a :6re hydrant on the lntcmotlon of 1411th Ave11ue SB and SB1 l~th Street. The :6re hydrant ls looated 112 blook uphill from the Mel!ker bo111e. Ml'. Clerapach noted tho Melzk,,r househOld experienced damage of the living space In the basement due to this act of vandalism. I called Ms. PcmnyMmlll. with~ Counl;Y Watcr/Si,werDlstrlot No. 90 on April 3, 1996. She oorulmled an IIDt otVllDdallsm bad occurred lnvolvlug fire bydnnts on :Febnwy 22, 1996. Addldonally, she bad a ~tded oomplailatirom 1161S 148th Avenue SE oo. this night· the night otthe vandalism. ( l<C WLRD N0.339 Th!• address is Ms. Metzkm'. Ms. l'v!etiker placed II call to SWM on the following date: Febmary 23, 1996. This drainage, problem does not qualify under the NDA Program criteria. The problem was not part of a natural st.otm·,6Vtlllt, 'The problem was QaUs«i by a:n isolated act ofV!Uldalism 1111d not a storm event. This was the fuEt flooding compllU{lt received since the compWnt logged in December of 1994. Mr. Raymond did upgrade his storm .conveyance 5Ystem since the original complaint My conversation with Mr. Raymond whild-on a site investigation, March 25, 1996 reviled the catch basin syotem located on the nortbeam.m portion of the property was adequate for the water received. At twit timo, Mr. Raymond's prlmary concern was the sheet flow com!Dg off the neighbor's property. Tirls sheet flow was obviously an isloabld event caused by the damaged iire hydrant. Having received no additional complaints for the last two major storm events, November, 199S and February 8, 1996, respectively, SWM considers the file closed. lid: :ci/HM--KC WLRD NO. 339 . KING COUNTY WATER~ RESOURCES DIVISION DRAINAGE 1NvESTIGATION REPORT Page 1: !NVEsTIGATIONREQUBST C'... Type--,-- OK'd by:J::f%::F:rr,ENo. gt{~()/'5 ( Received from: (Day) <4§> PHONE 25± -3g2J? (Eve) ~( _ __,} City @TDN State. __ Zip flo@ Lo ca.ti on of problem, if different: . .nname: Lot No: Block No: No field investigation required __ 'Jni• B®Jn ,WX':{ Col~istriot~ · CbargeNo. rlESPONSE: citizw{ iicitlJied o~ ~ _ by: ~ phone letter ._ in person P. '-.. -e Ff; .A1 t'.f ~_,, ~ 7'~ -1--r s~ ,e · cv ,:JU t-0 /II *' .v A-q ~P.;,.,t6, ,, e;i ,.._, 1r ro <.AJ ~ ,e/\ .,~ £.szJf tJct.J ,r ,e,_,r""°.,1.,./A. ,4e.. Cdv.o,..,. +J,.J D 6,4-1/'f' H f';( </.f.< ,u VM ,d ~ )ISl'OSITION: Turned to __ on _...,_,.____, __ by_ OR: No further action recommended because: _ Lead agency haa heim notified:·--------------------- :__ Problem has been coneoted. __ . No problem has been identlBcd. _ Prlor illvcstlgation addfesses problem: . lln!'n.111 ' _ Private problem -N,DAP will not consider because: __ Water prlg!Jiates onsite and/or on noighborlng parcel. Locatlon ls outside WLRD S~_J,rea. _Other(Speoify): IATE CLOSED: 31 7 I if By: ~ . /tvfc/f'/2.Pt/(~~ Complaint 99-0151 Rutledge Investigated by Pnt Simmons 03/01/99 I met with Ms. Rutledge about the drainage that flows in the Horse pn,ture behind her home. Tue water flows out of a pond/wetland and through a swa.le that Is about 50 feet from her South feuce. The water is about 2 feet wide on the West edse of her property and S-6 feetwld• on the East aide of the.parcel. This appears to be a natural drainage course that flows wh11n the wetland/pond get full enough. She would Wee to keep the stream narrow to allow more room for the horses. I stnted that I would look into t!te nature of this drain.age to see how it is protected under current codes and provit,le her with some information on the re1trictions near the drainage. 142nd Ave SE r D I ----. ________ 1 _____________ _ Pond/Wetland 11642 Rutledge I PIIStllre ---)> Pnlinaee swat• East Renton/Rosemonte -Early Start Technical Information Report 4 FLOW CONTROL AND WATER QUALITY DESIGN Since no impervious area will be added as part of the Early Start Grading Plans, no flow control or water quality treatment will be required. Job #01-047 June 25, 2008 !Vo r 11t\lt:..~v, i? UT ~(l I~ '{(.v.v;!lf{' Al-eed. /f'JS l·, ..... en/ Page 4-1 East Renton/Rosemonte -Early Start Technical Information Report 5 CONVEYANCE SYSTEM ANALYSIS & DESIGN The permanent storm drain system will not be constructed as part of the Early Start Plans, therefore no conveyance calculation were completed. Job #01-047 June 25, 2008 Page 5-2 East Renton/Rosemonte -Early Start Technical Information Report 6 SPECIAL REPORTS AND STUDIES 6. 1 Geotechnica/ Reports Please refer to the report Rosemonte-East Renton Property, by Associated Earth Science, Inc. dated November 12, 2007 located at the end of this section. 6.2 Wetland Determination Report Please refer to the report Wetland Determination for East Renton Property, by C. Gary Shulz dated September 12, 2002. 6.3 Wetland Recharge There are approximately 9.5 acres of wetlands and associated buffers (wetland complex) occupying the western portions of the two plats of East Renton/Rosemonte. On the attached Existing Wetland Tributary Area Exhibit these wetlands are identified as B, C, E and F. Wetlands B and C are located within the East Renton site and Wetland E and F are located within the Rosemonte site. This complex receives sheet flow runoff from the remaining upland portions of both sites. With development, it is proposed that both projects will be served by one detention facility (large combined detention/WQ treatment pond), located in a tract in the northeast comer of Rosemonte. This pond will be sized to provide Level One flow control and act as a sediment pond during early start grading-discharge from the pond will provide recharge to wetland F. In order to maintain hydrology to the remainder of the wetland complex, the yearly volume of runoff from the upslope area draining to it was calculated utilizing King County Runoff Time Series (KCRTS) methodology. Using KCRTS, the existing basin's I.I-year storm peak was determined to occur on 3/24/04. This date was then bracketed (6-months before and 6- months after) and the time series analyzed to determine the total annual runoff volume during that I-year period. The 1.1 year storm was selected because it is the lowest intensity and highest frequency storm that KCRTS can model. Job #01-047 June 25, 2008 Page 6-1 East Renton/Rosemonte -Early Start Technical Information Report Under early grading conditions, the goal is to maintain hydrology by recharging the wetland complex with runoff from portions of the cleared and graded site. The areas will contain drainage swales to convey runoff to the appropriate wetland recharge area that is needed to provide recharge equivalent to the existing conditions annual I. I-year volume. The areas are situated adjacent to or near the wetland complex. [See Early Start Wetland Recharge Area Exhibit] 6.3.1 Predeveloped Land Cover WETLANDB&C In the existing condition, 6.53 acres of the site is tributary to wetland B and C located near the western property line. This area is to be diverted away from the wetland after development. The following is a breakdown of the pre developed land cover. 1.96 acres Forest 0.09 acres Impervious ( driveways and roofs with 50% impervious multiplier) 4.48 acres Till Pasture 6.53 acres Total KCRTS Existing Peak B and C Flows Flow Frequency Analysis Time Series File:ext b & c.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- Flow Rate Rank Time of Peak (CFS) 0. 453 2 2/09/01 18:00 0.169 7 1/05/02 16:00 0. 403 3 2/28/03 3:00 0.045 8 3/24/04 19:00 0. 229 6 1/05/05 8:00 o. 379 4 1/18/06 16:00 0.361 5 11/24/06 4:00 0. 724 1 1/09/08 6:00 Computed Peaks KCRTS Existing Band C Volume Discharge Volume from Time Series ext b & c.tsf -----Flow Frequency Analysis------- --Peaks Rank Return Prob (CFS) Period 0.724 1 100.00 0.453 2 25.00 0.403 3 10.00 0.379 4 5.00 0.361 5 3.00 0.229 6 2.00 0.169 7 1.30 0.045 8 1.10 0.634 50.00 0.990 0.960 0.900 0. 800 0.667 0.500 0.231 0.091 0.980 between 09/24/03 00:00 and 09/23/04 23:59 39072. CU-Ft or 0.897 Ac-Ft in 365.0 days Job#01-047 June 25, 2008 Page 6-2 East Renton/Rosemonte -Early Start Technical Information Report WETLANDE&F In the existing condition, 2.50 acres of the site is tributary to wetland E and F located near the northwest corner of the site. This area is to be diverted away from the wetland after development. The following is a breakdown of the pre developed land cover. 2.50 acres Till Pasture 2.50 acres Total KCRTS Existing Peak E and F Flows Flow Frequency Analysis Time Series File:ext e & f.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--------Flow Frequency Analysis------- Flow Rate Rank Time of Peak --Peaks (CFS) (CFS) 0 .176 2 2/09/01 18:00 0.302 0.066 7 1/05/02 16:00 0.176 0.161 3 2/28/03 3:00 0.161 0. 017 8 3/24/04 19:00 0.150 0.090 6 1/05/05 8:00 0.145 0.150 4 1/18/06 16:00 0.090 0.145 5 11/24/06 4:00 0.066 0.302 1 1/09/08 6:00 0.017 Computed Peaks 0.260 KCRTS Existing E and F Volume Discharge· Volume from Time Series ext e & f.tsf between 09/24/03 00:00 and 09/23/04 23:59 Rank 1 2 3 4 5 6 7 8 18318. CU-Ft or 0.421 Ac-Ft in 365.0 days 6.3.2 Early Start Grading Land Cover WETLANDB&C Return Prob Period 100.00 0.990 25.00 0.960 10.00 0.900 5.00 0.800 3.00 0. 667 2.00 0.500 1. 30 0.231 1.10 0.091 50.00 0. 980 In the graded condition, 2.77 acres of the site will be directed to wetland B and C located near the western property line. The following is a breakdown of the land cover. 2. 77 acres Till Grass KCRTS Early Start Graded Peak B and C Flows Flow Frequency Analysis Time Series File:dev b & c.tsf Project Location:Sea-Tac Job#01-047 June 25, 2008 Page 6-3 East Renton/Rosemonte -Early Start Technical Information Report ---Annual Peak Flow Rates--------Flow Frequency Analysis------- Flow Rate Rank Time of Peak --Peaks (CFS) (CFS) 0.180 4 2/09/01 2:00 0.386 0.129 7 1/05/02 16:00 0.221 0.221 2 2/27/03 7:00 0 .190 0.119 8 8/26/04 2:00 0.180 0.148 6 10/28/04 16:00 0 .177 0.190 3 1/18/06 16:00 0.148 0.177 5 11/24/06 3:00 0 .129 0.386 1 1/09/08 6:00 0.119 Computed Peaks 0.331 KCRTS Early Start Graded Band C Volume Discharge Volume from Time Series dev b & c.tsf -- between 09/24/03 00:00 and 09/23/04 23:59 Rank 1 2 3 4 5 6 7 8 41182. Cu-Ft or 0.945 Ac-Ft in 365.0 days WETLANDE&F Basin Band C Existing Volume= Q 1.1 = 39,072 cu-ft Early Start Graded= Qu = 41,182 cu-ft Return Prob Period 100.00 0.990 25.00 0.960 10.00 0. 900 5.00 0.800 3.00 0.667 2.00 0.500 l. 30 0.231 1.10 0.091 50.00 0.980 In the graded condition, 1.39 acres of the site will be directed to wetland E and F located near the northwest corner of the developed site. The pond outflow is also tributary to wetland E but is not considered in this analysis. The pond outflow is located below wetland E and a portion of wetland F. The following is a breakdown of the developed land cover. 1.36 acres Till Grass 0.03 acres Impervious KCRTS Earl Start Graded Peak E and F Flows Flow Frequency Analysis Time Series File:dev e & f.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- Flow Rate Rank Time of Peak (CFS) 0 .129 0.068 0.163 0.033 0. 072 0 .132 0.119 0.302 Computed Peaks 4 7 2 8 6 3 5 1 2/09/01 1/05/02 2/27/03 8/26/04 1/05/05 1/18/06 11/24/06 1/09/08 2:00 16:00 7:00 2:00 8:00 16:00 3:00 6:00 -----Flow Frequency Analysis------- --Peaks Rank Return Prob (CFS) Period 0.302 1 100.00 0.990 0.163 2 25.00 0.960 0.132 3 10.00 0.900 0 .129 4 5.00 0.800 0.119 5 3.00 0.667 0 .072 6 2.00 0.500 0.068 7 1.30 0.231 0.033 8 1.10 0 .091 0.255 50.00 0.980 Job #01-047 June 25, 2008 /r.PJtP. ;....----- Page 6-4 East Renton/Rosemonte -Early Start Technical Information Report KCRTS Early Start Graded E and F Volume Discharge Volume from Time Series dev e & f.tsf between 09/24/03 00:00 and 09/23/04 23:59 22090. Cu-Ft or 0.507 Ac-Ft in 365.0 days Job #01-047 June 25, 2008 Basin E and F Existing Volume= Q1.1 = 18,318 cu-ft Early Start Graded Volume= Q1.1 = 22,090 cu-ft Page 6-5 Geotechnical Engineering Water Resources Environmental Assessments and Remediation Sustainable Development Services Geologic Assessments Associated Earth Sciences, Inc. Ctifrtfl!J'3 ij '9"M1;J' o/J&ti9t'6' Subsurface Exploration, Geologic Hazard, and Geotechnical Engineering Report ROSEMONT-EAST RENTON PROPERTY King County, Washington Prepared for CamWest Development, Inc. Project No. KE040766B November 12, 2007 , Associated Earth Sciences, Inc. ~' [lj' ~··· • ,~~.· ··.1:.:· ~-;;;;.~. n . -~; ., ' ':;-.·.-. Cefe6ratiYIJ Over 251f ears of.S'ervice November 12, 2007 Project No. KE040766B CamWest Development, Inc. 9720 NE 1201h Place, Suite 100 Kirkland, Washington 98034 Attention: Subject: Ms. Jennifer Reiner Subsurface Exploration, Geologic Hazard, and Geotechnical Engineering Report Rosemont-East Renton Property King County, Washington Dear Ms. Reiner: We are pleased to present the enclosed copies of the above-referenced report. This report summarizes the results of our subsurface exploration, geologic hazard, and geotechnical engineering study, and offers recommendations for design and development of the proposed project. This report is intended to replace our April 23, 2003 geotechnical report completed for the "Ironwood Property" for Northward Homes. · We have enjoyed working with you on this study and are confident that the recommendations · presented in this report will aid in the successful completion cif your project. Should you have any questions, or if we can be of additional help to you, please do not hesitate to call. Sincerely, ASSOCIATED EARTH SCIENCES, INC. Kirkland, Washington Kurt D. Merriman, P.E. Principal Engineer KDM/o KE0476681 Projecta\20040766\KE\ WP Kirkland 425-827-7701 • Everett 425-259-0522 www.aesgeo.com D Tacoma 253-722-2992 SUBSURFACE EXPLORATION, GEOLOGIC HAZARD, AND GEOTECHNICAL ENGINEERING REPORT ROSJEMONT-JEA§T JRJENTON PROPERTY King County, Washington Prepared for: Cam West Development, Inc. 9720 NE 1201h Place, Suite 100 Kirkland, Washington 98034 Prepared by: Associated Earth Sciences, Inc. 911 51h Avenue, Suite 100 Kirkland, Washington 98033 425-827-7701 Fax: 425-827-5424 November 12, 2007 Project No: KE040766B Rosemont-East Remon Property King County, Washington Subswface F.xploration, Geologic Hazard, and Geotechnica/ Engineering Repo11 Project and Site Conditions I. PROJECT AND SITE CONDITIONS 1.0 INTRODUCTION This report presents the results of our subsurface exploration, geologic hazard, and geotechnical engineering study for the Rosemont-East Renton Property located east of 148"' Avenue SE, roughly between SE 117'" and SE 120'" Streets in King County, Washington. This report is intended to replace our previous report dated April 23 ,. 2003 for the "Ironwood Property" prepared at that time for Northward Homes. CamWest Development, Inc. (CamWest) has subsequently purchased the property and combined it with the "East Renton" (southern portion of the site) and re-named the northern portion of the site "Rosemont." The site location is shown on Figure I, "Vicinity Map." The recently completed site and grading plan and approximate locations of the explorations accomplished for this study are presented on the "Site and Exploration Plan," Figure 2. The explorations were completed in the general areas of the proposed lots, detention facilities, and streets. If development plans change, the conclusions and recommendations contained in this report should be reviewed and modified, or verified, if necessary. 1.1 Purpose and Scope The purpose of this study was to provide subsurface soil and ground water data to be utilized in the design and development of the above-referenced project. Our study included a review of available geologic literature including soils data from the referenced 2003 report and supplemental exploration pits excavated within proposed detention tracts in 2004 and excavation of 12 new exploration pits. We also performed geologic studies to assess the type, thickness, distribution, and physical properties of the subsurface sediments and ground water conditions. Limited geologic hazard evaluations and engineering studies were also conducted to determine suitable geologic hazard mitigation techniques, the type of suitable foundations for new structures, allowable soil foundation bearing pressures, anticipated settlements, retaining wall lateral pressures, floor support recommendations, and drainage considerations. This report summarizes our current fieldwork and offers hazard mitigation and development recommendations based on our present understanding of the project. 1.2 Authorization Authorization to proceed with this study was granted by CamWest. This report has been prepared for the exclusive use of CamWest and their agents for specific application to this project. Within the limitations of scope, schedule, and budget, our services have been performed in accordance with generally accepted geotechnical engineering and engineering geology practices in effect in this area at the time our report was prepared. No other warranty, express or implied, is made. November 12, 2007 ASSOCIATED EARTH SCIENCES, INC. SGBhs-KE(U766BJ -Proj,ctsl100407661KE\WP Page 4 Rosemont-East Renton Property King Comuy, Washington 2.0 PROJECT AND SITE DESCRIPTION Subswface Exploration, Geologic Hazard, and Geoteclmical Engineering Report Project and Site Conditions This report was completed with an understanding of the project based on conversations with Ms. Rebecca Cushman of Triad Associates, review of proposed lot and street layout and grading plans, review of King County Preliminary Plat Application review conunents dated April 10, 2007, and familiarity with our previous geotechnical work performed in the site area . . Present plans call for demolition of two existing houses and several outbuildings and the construction of 91 single-family units, new streets, two storm water detention facilities, and associated development improvements. Access to the new development will be from 148'11 Avenue SE via a new residential collector designated on the referenced plans as SE 119~ Street. The site is located west of 148~ Avenue SE and east of the Renton city limits, approximately \4 mile south of SR 900 in King County, Washington. Wood-framed, single-family homes occupy the northeast and southeast corners of the property. Several large outbuildings are located west of both houses. A domestic water well is located near the northern homesite. The site slopes moderately down to the west to a wetland that occupies the western one-third of the property. The wetland contained both standing and flowing surface water at the time of our site visits. Total<fvaluatio'iry:hange across the property is on the order of 100 feet. The east side of the site is predominately developed with pasture overgrown with blackberries and Scotch broom with scattered trees and grass within the areas surrounding the existing houses. The west side of the site is covered with wetland vegetation and mature trees. The area near the northwest site corner has been developed under a different CamWest plat. The site is surrounded by large tracts of rural and densely-spaced, new residential tracts. 3.0 SUBSURFACE EXPLORATION Our field study included advancing 19 exploration pits on April 8, 2003 within the Rosemont tract (formerly Ironwood Property), two exploration pits in 2004 within the proposed detention tracts, and 12 new exploration pits within the East Renton tract (formerly Rosemont). We completed three exploration borings on October 4, 2007 within the proposed detention facility footprints. We also performed a geologic reconnaissance to gain information about the site. The various types of sediments, as well as the depths where characteristics of the sediments changed, are indicated on the exploration logs presented in Appendix A. The depths indicated on the logs where conditions changed may represent gradational variations between sediment types. Our explorations were approximately located in the field by measuring from known site features shown on the "Site and Exploration Plan" and their locations and elevations should be considered approximate. November 12, 2007 ASSOCIATED EARTH SCIENCES, INC. SGB//s -KE0476681 -Projects\20040766IKE\WP Page 5 Rosemont-East Renton Prope,1y King Co11111y, Washington S11bs111face Exploration, Geologic Hazard, and Geoteclmical Engineering Report Pro;ect and Site Conditions The conclusions and recommendations presented in this report are based on the explorations completed for this and previous studies. The number, locations, and depths of the explorations were completed within site, time, and budgetary constraints. Because of the nature of exploratory work below ground, extrapolation of subsurface conditions between field explorations is necessary. It should be noted that differing subsurface conditions may sometimes be present due to the random nature of deposition and the alteration of topography by past grading and/or filling. The nature and extent of any variations between the field explorations may not become fully evident until construction. If variations are observed at that time, it may be necessary to re-evaluate specific recommendations in this report and make appropriate changes. 3.1 Exploration Pits All exploration pits were excavated with a trackhoe either under subcontract to Associated Earth Sciences, Inc. (AES!) or CamWest. The pits permitted direct, visual observation of subsurface conditions. Materials encountered in the exploration pits were studied and classified in the field by an engineering geologist or geotechnical engineer from our firm. All exploration pits were backfilled immediately after examination and logging. Selected samples were then transported to our laboratory for further visual classification and testing, as necessary. Laboratory testing was only performed on the samples collected during our most recent subsurface exploration from the East Renton property. 3.2 Exploration Borings The exploration borings were completed by advancing a 33/,-inch, inside-diameter; hollow- stem auger with a track-mounted drill rig to depths ranging from 11.5 to 36.5 feet. During the drilling process, samples were obtained at generally 2.5-or 5-foot-depth intervals. The borings wete continuously observed and logged by a geotechnical engineer from our firm. The exploration logs presented in Appendix A are based on the field logs, drilling action, and inspection of the samples secured. Disturbed but representative samples were obtained by using the Standard Penetration Test (SPT) procedure in accordance with American Society for Testing and Materials (ASTM):D 1586. This test and sampling method consists of driving a standard, 2-inch, outside-diameter, split-barrel sampler a distance of 18 inches into the soil with a 140-pound hammer free-falling a distance of 30 inches. The number of blows for each 6-inch interval is recorded and the number of blows required to drive the sampler the final 12 inches is known as the Standard Penetration Resistance ("N") or blow count. If a total of 50 is recorded within one 6-inch interval, the blow count is recorded as the number of blows for the corresponding number of inches of penetration. The resistance, or N-value, provides a measure of the relative density of granular soils or the relative consistency of cohesive soils; these values are plotted on the attached boring log. November 12, 2007 ASSOCIATED EARTH SCIENCES, INC. SGBh1 -KE047668/ -Pro}ectsl20040766IKEIWP Page 6 Rosemont-East Renton Property Ki11g County, Washi11gto11 Subswface Exploration, Geologic Hazard, a11d Geotec/111ical Engineering Report Project and Site Conditions The samples obtained from the split-barrel sampler were classified in the field and representative portions placed in watertight containers. The samples were then transported to our laboratory for further visual classification and laboratory testing, as necessary. Laboratory testing data is summarized below and included in Appendix A. 4.0 SUBSURFACE CONDITIONS Subsurface conditions at the project site were inferred from the field explorations accomplished for this study and visual reconnaissance of the site. As shown on the field logs, the exploration pits generally encountered fill materials of various thickness and composition near the northwest and southeast corners of the proposed development area overlying various glacially derived sediments. In one exploration pit near the southwestern corner of the proposed development area, we identified colluvium over glacial recessional outwash sediments overlying pre-Vasl)on sedimentary deposits consisting of stiff to hard peat and silt. Although isolated· areas of out wash were encountered near the ground surface, till was the predominant soil encountered throughout the site, as mapped on Figure 2. At this site there appears to be a somewhat thin till cap along the upper elevations of the property that thickens to the southeast. The site slopes down to the west and northwest into a large, eroded (during the Pleistocene), roughly north-south trending valley. Where recessional outwash was encountered and not underlain by till, the till was likely eroded during formation of thi_s valley. The recessional outwash was then likely deposited directly upon the underlying sediments identified within the northern explorations as advance outwash or pre-Fraser (interglacial) sedimentary deposits at the southwest development area. Figure 3 presents a cross section through the proposed storm water detention pond (Section A-A' on Figure 2). Review of the Geologic Map of King County, Washington, by Derek Booth, et al. (2006) indicates that the area of the subject site is underlain by Vashon lodgement till with advance outwash and wetland deposits mapped to the west. Our interpretations of the sediments encountered during our study are in general agreement with this regional geologic map. The following section presents more detailed subsurface information organized from the shallowest (youngest) to the deepest (oldest) sediment types. 4.1 Stratigraphy Brush/Forest Duff/Topsoil/Co/luvium A layer of organic-rich soil classified as sod or brush, forest duff, topsoil, and/or colluvium was encountered at the surface in all of the exploration pits. The organic-tich soil was between 0.5 and 1.5 feet thick. In EP-4 (2007) a layer of colluvium approximately 4 feet thick was encountered. Colluvium is soil that has moved downslope by the forces of gravity. These November 12, 2007 ASSOCIATED EARTH SCIENCES, INC. SGBhs -KE04766BJ -Profects\20040766IKEIWP Page 7 Rosemont-East Renton Property King County, Washington Subswface Exploration, Geologic Hazard, and Geotechnical Engineering Report Project and Site Conditions soils are not considered suitable for structural, roadway, or fill slope support due to its compressive and unstable nature. Fill Approximately 1.5 to IO feet of fill was encountered in the exploration pits located primarily in the northwest and southeast corners of the proposed development area (See Figure 2). The fill was encountered in recent exploration pits EP-1 and EP-2, and in the 2003 exploration pits EP-11, EP-12, EP-13, EP-17, and EP-18. Fill is also expected around the existing homes, outbuildings, septic systems, and other existing underground utilities. The fill generally consisted of loose, moist to wet, fine to coarse sand with variable amounts of silt, gravel, organic material, and debris such as concrete and asphalt chunks. The fill is not considered suitable for foundation, fill slope, roadway, or utility support due to its loose and variable condition and organic and debris content. Vashon Recessional Outwash A recessional outwash deposit consisting of medium dense, stratified sand and silty sand with variable amounts of gravel was encountered in exploration pit EP-4 and exploration boring EB-2 (2007) and exploration pits EP-12, EP-13, EP-14, and EP-16 (2003), primarily in explorations completed nearest the on-site wetland. Meltwater streams flowing off of the retreating Vashon-age ice sheet that once occupied the Puget Sound area deposited the recessional outwash sand. The recessional outwash is suitable for building support, though some preparation and compaction may be needed prior to placement of structures on this material. The recessional outwash is estimated to have a high permeability rate, but is somewhat stratified which will limit its permeability. Within the proposed detention pond area, the recessional outwash is composed primarily of low-permeability silt. Vashon Lodgment Till Vashon Lodgment till was encountered in all 2007 explorations except EP-4, and in EP-2 and EP-3 (2004), and EP-16, EP-18, and EP-21 (2003). The till consisted of medium dense grading to very dense, silty fine to coarse sand containing fine to coarse gravel and cobbles and occasional boulders. The medium dense to very dense till is suitable for structural support, and is considered moisture-sensitive. The lodgment till was deposited at the base of the Vashon-age glacial ice sheet and was subsequently overridden by several thousand feet of ice. Consequently, these .materials are generally dense to very dense, possess high shear strength, low compressibility characteristics, and are relatively impermeable. The upper portions of the till are generally weathered and less dense, oxidized brown, and siltier than the lower, unweathered portions of the deposit. The site can be considered a "till" site hydrologically, given that till covers the majority of the development area. November 12, 2007 ASSOCIATED EARTH SCIENCES, INC. SGBIU -KE047668/ -Projrcu\20040766IKE\WP Page 8 Rosemont-East Renton Property King County, Washington Vashon Advance Outwash Subswface Exploration. Geologic Hazard, and Geoiechnical Engineering Report Project and Site Conditions An advance outwash deposit consisting of medium dense to dense sand and gravel to hard sandy silt was encountered below the till in EP-6, EB'.l, EB-2, and EB-3 (2007). Advance outwash was also encountered in exploration pits EP-15 through EP-22 (2003) either beneath the till or overlying fill, recessional outwash, or topsoil. Meltwater streams flowing off of the advancing Vashon-age glacial ice sheet that once occupied the Puget Sound area deposited the outwash ahead of the glacial front and were subsequently overridden by several thousand feet of ice. The advance outwash deposit is suitable for building support. The advance outwash is estimated to have a wide range of permeability rates as it is highly stratified and over- consolidated. Pre-Fraser Sedimentary Deposits In EP--4 (2007), we encountered stiff to hard, interbedded, dark brown, organic peat and silt. These sediments were likely deposited in a wetland setting during the last inter-glacial period prior to the glacial ice sheet occupying this area of the Puget Sound. The depth and aerial extent of this interbedded peat/silt deposit is currently unknown. However, given the over- consolidated nature of this deposit, it is unlikely that significant settlement of fill or structures placed over these sediments will occur during the life of the project. 4.2 Hydrology Varying amounts of shallow ground water seepage, ranging from very heavy to very slight, were encountered in most of the exploration pits excavated in April of 2003. Ground water seepage was encountered in EP-4, EB-1, and EB-3 during our recent exploration program. Advance outwash soils identified in EP-6 and EB-2 were also wet and/or mottled indicating that seasonal ground water likely occurs to supply water to the nearby wetlands. The ground water seepage encountered in our exploration pits is interpreted to be perched in the looser soils or coarser-grained soils, such as the fill, the recessional outwash, the weathered till, and the advance outwash. The quantity and duration of seepage of the perched ground water was quite variable and depends on topography, soil grain size, on-and off-site land usage, and seasonal variations in the amount of precipitation. 4.3 KCRTS Soil Group Considerations Based on the site-specific explorations completed for this study, it is our opinion site soils should generally be considered till for purposes of King County Runoff Time Series (KCRTS) modeling. As illustrated on Figure 2, most of the proposed development area is underlain by till. Isolated areas of recessional or advance outwash have a limited distribution on the site. November 12, 2007 ASSOCIATED EARTH SCIENCES. INC. SGB/u -KEfH766BJ -Pro}tets120040766jKE\WP Page 9 Rosemont-East Renton Property King County, Washington 4 .4 Laboratory Test Results Subswface Exploration, Geologic Hazard, and Geotechnical Engineering Report Project and Site Conditions Laboratory testing on selected soil samples from explorations was completed in accordance with the requirements set forth in the request for proposal issued by CamWest. Laboratory testing results are also included in Appendix A. Moisture contents were tested in accordance with ASTM:D 2216. Grain size analysis was performed in accordance with ASTM:D 422 and D 1140. The maximum dry density of three soil samples was determined using the modified Proctor test procedure (ASTM:D 1557). The results are as follows in Table I. Other laboratory test results are included in Appendix A. Table I Maximum Dry Density Optimum Moisture Content Samole Location Samole Tvne (ncl)m (percent)"' EP-1@3-4' Till (south oarcel) 121.0 12.5 EP-2@ 1.5 -4' Weathered Till (south) 118.0 14.5 EP-t5 @6' Till (north parcel) 137.0 9.5 m pcf = pounds per cubic foot. 12) Reported results are not corrected for gravel content. November 12, 2007 ASSOCIATED EARTH SCIENCES, INC. SGB//s -K!,0476681 -Pro}wsl200407661 KEI WP Page 10 Rosemont-East Renton Property King County, Washington Subswface Exploration, Geologic Hazard, and Geotechnical Engineering Report Geologic Hazards and Mitigations II. GEOLOGIC HAZARDS AND MITIGATIONS The following discussion of potential geologic hazards is based on the geologic conditions as observed and discussed herein. The King County Sensitive Areas Folio was reviewed and no Landslide Areas or Erosion Hazard areas were shown for the site. 5.0 SLOPE STABILITY HAZARDS AND RECOMMENDED MITIGATION The site contains moderate slopes, especially along the western edge of the proposed development area. However, none of the slopes appear to exceed the King County criteria for steep slopes of greater than 40 percent inclination. Where these slopes contain fill, colluvium and recessional outwash, the risk of landsliding, especially during seismic shaking, is generally moderate. However, provided loose soil and colluvium are removed during site grading and our recommendations for keying and benching any new fill into the existing slopes are followed, it is our opinion that the risk of slope instability will be mitigated. Where till or advance outwash underlie the moderately inclined slopes, the risk of landsliding is considered low. 6.0 SEISMIC HAZARDS AND RECOMMENDED MITIGATION Earthquakes occur in the Puget Lowland with great regularity. Most of the seismic events are small and are usually not felt by people. However, large earthquakes do occur as evidenced by the 1949, 7.2-magnitude event, the 1965, 6.5-magnitude event, and the 2001, 6.8-magnitude event. The 1949 earthquake appears to have been the largest in this region during recorded history and was centered in the Olympia area. Evaluation of earthquake return rates indicates that an earthquake of the magnitude between 5.5 and 6.0 is every 25 to 40 years in the Puget Sound Basin. Generally, there are four types of potential geologic hazards associated with large seismic events: 1) surficial ground rupture; 2) seismically induced landslides; 3) liquefaction; and 4) ground motion. The potential for each of these hazards to adversely impact the proposed project is discussed below. · 6.1 Surficial Ground Rupture The nearest known fault trace to the project site is the Seattle Fault. The southern edge of this fault zone is located approximately 5 miles to the north. Recent studies by the U.S. Geological Survey (USGS) (e.g., Johnson et al., 1994, Origin and Evolution of the Seattle Fault and Seattle Basin, Washington, Geology, v. 22, pp. 71-74; and Johnson et al., 1999, Active November I 2, 2007 ASSOCIATED EARTH SCIENCES, INC. SGB//J -KEOl/76681 -Projtcfl\20040766!KE\WP Page 11 Rosemont-East Renton Property King County, Washington Subswface Exploration, Geologic Hazard, and Georechnical Engineering Report Geologic Hazards and Mitigations . Tectonics of the Seattle Fault and Central Puget Sound Washington -Implications for Earthquake Hazards, Geological Society of America Bulletin, July 1999, v. Ill, n. 7, pp. 1042-1053) have provided· evidence of surficial ground rupture along a northern splay of the Seattle Fault. The recognition of this fault splay is relatively new and data pertaining to it are limited with the studies still ongoing. According to the USGS studies, the latest movement of this fault was about 1,100 years ago when about 20 feet of surficial displacement took place. This displacement can presently be seen in the form of raised, wave-cut beach terraces along Alki Point in West Seattle and Restoration Point at the south end of Bainbridge Island. The recurrence interval of movement along these fault systems is still unknown, although it is hypothesized to be in excess of several thousand years. Due to the suspected long recurrence interval and distance from the site, the potential for surficial ground rupture is considered to be low during the expected life of the proposed structures. 6.2 Seismically Induced Landslides The site contains moderate slopes, especially along the western edge of the proposed development area. However, none of the slopes appear to exceed the King County criteria for steep slopes of greater than 40 percent inclination. Where these slopes contain fill, colluvium, and recessional outwash, the risk of landsliding, especially during seismic shaking, is generally moderate. However, provided loose soil and colluvium are removed during site grading and our recommendations . for keying and benching any new fill into the existing slopes are followed, it is our opinion that the risk of slope instability will be mitigated. Where till or advance outwash underlie the moderately inclined slopes, the risk of landsliding is considered low. 6.3 Liquefaction The till and advance outwash generally have a low potential for liquefaction due to the dense state of the material. However, where saturated recessional outwash or loose fill occur, the liquefaction hazard is higher. These areas of the site are limited in aerial extent and thickness. In order to mitigate this hazard, the existing fill should be removed from the proposed construction area and new slope or detention pond berm fill should be properly keyed and benched into suitable native bearing soils. 6.4 Ground Motion The guidelines presented in the 2006 International Building Code (IBC) Section 1613 should be used in the seismic design of the project. The USGS Earthquake Hazards Program web site (http://earthguake.usgs.gov/hazmaps/) was used to determine interpolated probabilistic ground motion values in percent · of gravity (g) for an event with a return period of 2 percent exceedance in 50 years. Using the web site, the project area was submitted using latitude and longitude for mapped spectral accelerations of S, = 1.22 for short periods (0.2 seconds) and S, November 12, 2007 SGBlls -KE04766Bl -Projtm\20040766IKE\WP ASSOCIATED EARTH SCIENCES, ENC Page 12 Rosemont-East Renton Prope11y King County, Washington Subswface Exploration, Geologic Hazard, and Geotechnical Engineering Report Geologic Hazards and Mitigations = 0.47 for a I-second period. Based on the results of our subsurface exploration and our estimation of soil properties at depth utilizing available geologic data, Site Class "C" in conformance with Table 1613.5.2 of the IBC may be used. 7.0 EROSION HAZARDS AND MITIGATIONS As of October I, 2006, the Washington State Department of Ecology (Ecology) Construction Storm Water General Permit (also known as the National Pollutant Discharge Elimination System [NPDES] permit) requires weekly Temporary Erosion and Sedimentation Control (TESC) inspections for all sites 1 or more acres in size that discharge storm water to surface waters of the state. The TESC inspections must be completed by a Certified Erosion and Sediment Control Lead (CESCL) for the duration of the construction. TESC reports do not need to be sent to Ecology, but should be logged into the project Storm Water Pollution Prevention Plan (SWPPP). If the project does not require a SWPPP, the TESC reports should be kept in a file on-site, or by the permit holder if there is no facility on-site. Ecology also requires weekly turbidity monitoring by a CESCL of storm water leaving a site for all sites 5 acres or greater. Ecology requires a monthly summary report of the turbidity monitoring results (if performed) signed by the NPDES permit holder. If the monitored turbidity eqnals or exceeds 25 nephelometric turbidity units (NTU) (Ecology benchmark standard), the project . . best management practices (BMPs) should be modified to decrease the turbidity of storm water leaving the site. Changes and upgrades to the BMPs should be continued until the weekly turbidity reading is 25 NTU or lower. If the monitored turbidity exceeds 250 NTU, the results must be reported to Ecology within 24 hours and corrective action taken. Daily turbidity monitoring is continued until the corrective action lowers the turbidity to below 25 NTU. In order to meet the current Ecology requirements, a properly developed, constructed, and maintained erosion control plan consistent with the local King County standards and best management erosion control practices will be required for this project. AES! is available to / assist the project civil engineer in developing site-specific erosion control plans. Based on past experience, it will be necessary to make adjustments and provide additional measures to the TESC plan in order to optimize its effectiveness. Ultimately, the success of the TESC plan depends on a proactive approach to project planning and contractor implementation and maintenance. The erosion hazard of the site soils is high. The most effective erosion control measure is the maintenance of adequate ground cover. Maintaining cover measures atop disturbed ground provides the greatest reduction to the potential generation of . turbid runoff and sediment transport. During the local wet season (October 1" through March 31 "), exposed soil should not remain uncovered for more than 2 days unless it is actively being worked. Ground cover measures can include erosion control matting, plastic sheeting, straw mulch, crushed rock or recycled concrete, or mature hydroseed. November 12, 2007 ASSOCIATED EARTH SCIENCES, INC. SOB/fr -K.ED4766BI -Projtm\20040766IKE\WP Page 13 Rosemom-East Renton Property Ki11g Cowity, Washington Subswface Exploration, Geologic Hazard, and Geotechnical Engineering Report Geologic Hazards and Mitigations Flow control measures· are also essential for collecting and controll\ng the site runoff. Flow paths across slopes should be kept to less than 50 feet in order to reduce the erosion and sediment transport potential of concentrated flow. Ditch/swale spacing will need to be shortened with increasing slope gradient. Ditches and swales that exceed a gradient of about 7 to 10 percent, depending on their flow length, should have properly constructed check dams installed to reduce the flow velocity of the runoff and reduce the erosion potential within the ditch. Flow paths that are required to be constructed on gradients between 10 to 15 ·percent should be placed in a riprap-lined swale with the riprap properly sized for the flow conditions. Flow paths constructed on slope gradients steeper than 15 percent should be placed in a pipe slope drain. AES! is available to assist the project civil engineer in developing a suitable erosion control plan with proper flow control. Some fine-grained surface soils are the result of natural weathering processes that have broken down parent materials into their mineral components. These mineral components can have an inherent electrical charge. Electrically charged mineral fines will attract oppositely charged particles and can combine (flocculate) to form larger particles that will settle out of suspension. The sediments produced during the recent glaciation of Puget Sound are, however, most commonly the suspended soils that are carried by site storm water. The fine-grained fraction of the glacially derived soil is referred to as "rock flour," which is primarily a silt-sized particle with no electrical charge. These particles, once suspended in water, may have settling times in periods of months, not hours. Therefore, the flow length within a temporary sediment control trap or pond has virtually no effect on the water quality of the discharge since it is not going to settle out of suspension in the time it takes to flow from one end of the pond to the other. Reduction of turbidity from a construction site is almost entirely a function of cover measures and flow control. Temporary sediment traps and ponds are necessary to control the release rate of the runoff and to provide a catchment for sand-sized and larger soil particles, but are very ineffective at reducing the turbidity of the runoff Silt fencing should be utilized as buffer protection and not as a flow-control measure. Silt fencing is meant to be placed parallel with topographic contours to prevent sediment-laden runoff from leaving a work area or entering a sensitive area. Silt fences should not be placed to cross contour lines without having separate flow control in front of the silt fence. A swale/berm combination should be constructed to provide flow control rather than let the . runoff build up behind the silt fence and utilize the silt fence as the flow-control measure. Runoff flowing in front of a silt fence will cause additional erosion and usually will cause a failure of the silt fence. Improperly installed silt fencing has the potential to cause a much larger erosion hazard than if the silt fence was not installed at all. The use of silt fencing should be limited to protect sensitive areas, and swales should be used to provide flow control. November 12, 2007 ASSOCIATED EARTH SCIENCES, INC. SGB!u -KEJU7668J -Projtcu\200407661 KE\WP Page 14 Rosemont-East Re11ton Property King County, Washington 7. I Erosion Hazard Mitigation Subswface Exploration, Geologic Hazard, and Geoiechnical Engineering Report Geologic Hazards and Mitigations To mitigate the erosion hazards and potential for off-site sediment transport, we would recommend the following: I. The winter performance of a site is dependent on a well-conceived plan for control of site erosion and storm water runoff. It is easier to keep the soil on the ground than to remove it from storm water. The owner and the design team should include adequate ground cover measures, acces& roads, and staging areas in the project bid to give the selected contractor a workable site. The selected contractor needs to be prepared to implement and maintain the required measures to reduce the amount of exposed ground. A site maintenance plan should be in place in· the event storm water turbidity measurements are greater than the Ecology standards. 2. All TESC measures for a given area to be graded or otherwise worked should be installed prior to any activity within an area other than installing the TESC features or timber harvesting. The recommended sequence of construction within a given area after timber harvesting would be to install sediment traps and/or ponds and establish perimeter flow control prior to starting mass grading. 3. During the wetter months of the year, or when large storm events are predicted during the summer months, each work area should be stabilized so that if showers occur, the work area can receive the rainfall without excessive erosion or sediment transport. The required measures for an area to. be "buttoned-up" will depend on the time of year and the duration the area will be left unworked. During the winter months, areas that are to be left unworked for more than 2 days should be mulched or covered with plastic. During the summer months, stabilization will usually consist of seal-rolling the subgrade. Such measures will aid in the contractor's ability to get back into a work area after a storm event. The stabilization process also includes establishing temporary storm water conveyance channels through work areas to route runoff to the approved treatment facilities. 4. All disturbed areas should be revegetated as soon as possible. If it is outside of the growing season, the disturbed areas should be covered with mulch, as recommended in the erosion control plan. Straw mulch provides the most cost-effective cover measure and can be made wind-resistant with the application of a tackifier after it is placed. 5. Surface runoff and discharge should be controlled during and following development. Uncontrolled discharge may promote erosion and sediment transport. Under no circumstances should concentrated discharges be allowed to flow over the top of steep slopes. November 12, 2007 ASSOCIATED EARTH SCIENCES, INC. SGB/ls-KE04766Bl -Pro}tcts\10040766IKE\WP Page 15 Rosemont-East Renton Property King County, Washington Subsurface Exploration, Geologic Hazard, and Geotechnical Engineering Repon Geologic Hazards and Mitigations 6. Soils that are to be reused around the site should be stored in such a manner as to reduce erosion from the stockpile. Protective measures may include, but are not limited to, covering with plastic sheeting, the use of low stockpiles in flat areas, or the use of straw bales/silt fences around pile perimeters. During the period between October l" and March 31", these measures are required. 7, On-site erosion control inspections and turbidity monitoring (if required) should be performed in accordance with the Ecology requirements, Weekly and monthly reporting to Ecology should be performed on a regularly scheduled basis, TESC monitoring should be part of the weekly construction team meetings, Temporary and permanent erosion control and drainage measures should be adjusted and maintained, as necessary, at the time of construction. It is our opinion that with the proper implementation of the TESC plans and by field-adjusting appropriate mitigation elements (BMPs) during construction, as recommended by the erosion control inspector, the potential adverse impacts from erosion hazards on the project may be mitigated. November 12, 2007 ASSOCIATED EARm SCIENCES, INC. SGDhs-KE04766BI -Pro/ects\200407661KE\WP Page 16 ) Rosemont-East Renton Property King County, Washington 8.0 INTRODUCTION Subsurface Exploration, Geologic Hazard, and Geotechnical Engineering Repol't Design Recommendations III. DESIGN RECOMMENDATIONS Our explorations indicate that, from a geotechnical standpoint, the parcel is suitable for the proposed development provided that the recommendations contained herein are properly followed. The bearing strata ranges from approximately 2 to 10 feet in depth below the ground surface across a portion of the site generally located in the northwest corner of the development area, east of the wetlands. The depth to bearing soils across the rest of the site was between about 0.5 and approximately 2 feet below existing site grades. The site soils were generally above their optimum moisture content for compaction, thus their reuse as fill during all but the driest times of the year will be difficult. In addition, many of the exploration pits encountered significant amounts of shallow ground water. The current grading plan shows new fill is to be placed above the area shown on Figure 2 containing thick, existing, uncontrolled fill soils. Since the existing fill is loose and unstable in its current condition, we recommend that the existing fill be removed within the area where new fill will be placed. As an alternative to removing and repl&cing the existing fill within these building lots, some type of deep foundation, such as small-diameter pipe piles (4-to 6- inch-diameter) and/or rock trenches bearing on the lower, dense, natural soils is recommended for building support throughout the previously filled portion of the site. If the deep foundation . option is chosen and the new buildings will have slab-on-grade floors, we recommend that the upper 2 feet of soil below the slab subgrade elevation consist of new, compacted, free-draining structural fill. If the slabs are settlement sensitive· then the floor slabs should also be pile supported. No new structural fill would be required under the floors if the buildings utilize crawl space construction techniques. In addition we recommend that the new street and driveway sections in this fill area be placed on at least 2 feet of new, compactc:J!.rn.11.c;_tm:alfill to limit settlement differential. Conventional shallow spread footings are anticipated for the remainder of the site. Ground water was encountered in many of the explorations, especially on the north and west portions of the site. Some of the excavations for ponds, underground utilities, and general site grading are expected to encounter this ground water. The use of interceptor trenches, swales, sunips, and other methods of ground water control will therefore be necessary in areas where seepage is encountered. November 12, 2007 ASSOCIATED EARTH SCIENCES, INC. SGBhJ -KE04766BI -ProjectJ\20040766IKE\WP Page 17 Rosemom-East Renton Property king County, Washington 9.0 SITE PREPARATION Subswface Exploration, Geologic Hazard, and Geotechnical Engineering Report Design Recommendations Any existing structures presently on the site, which are located under new construction areas, · should be removed. Any buried utilities should be removed or relocated if they are also under new construction areas. The resulting depressions should be backfilled with structural fill as discussed under the "Structural Fill" section if they are located below new foundation or pavement areas. As noted previously, a domestic well is located on the property. If the well will not be used in the future, it should be properly abandoned. Specific standards for abandonment of wells depend on the type of well in question. Ecology presents this information in a publication entitled Minimum Standards for Construction and Maintenance of Water Wells. The water well most likely will need to be legally abandoned by a Washington State Licensed Water Well Driller. Local health district and King County regulations may also apply. Site preparation should also include removal of all vegetation. Additionally, the upper organic sod, forest duff, topsoil, and colluvium should be removed from areas to receive new fill or other improvements, and the remaining roots grubbed. Areas where loose, surficial soils exist due to grubbing and demolition operations should be considered as fill to the depth of disturbance and treated as subsequently recommended for structural fill placement. Existing deep fill within the new building footprints could be left in place provided a deep foundation system is used to support the structure and no highly organic areas, areas of demolition waste, or other adverse materials or conditions are encountered when topsoil stripping is completed. Removal of shallow obstacles to facilitate pile driving is expected to be possible with a backhoe. 9. I Temporary Cut Slopes In our opinion, stable construction slopes should be the responsibility of the contractor and should be determined during construction. For estimating purposes, however, temporary, unsupported cut slopes can be planned at IH:lV (Horizontal:Vertical) or flatter in the lodgement till and l.5H:1V in the unsaturated advance and recessional outwash deposits and existing fill. Where loose, saturated soil is present, shoring or flatter slope angles may be necessary These slope angles are for areas where ground water seepage is not encountered, and assume that surface water is not allowed to flow across the temporary slope faces. If ground or surface water is present when the temporary excavation slopes are exposed, flatter slope angles will be required. As is typical with earthwork operations, some sloughing and raveling may occur and cut slopes may have to be adjusted in the field. In addition, WISHA/OSHA regulations should be followed at all times. November 12, 2007 ASSOCIATED EARTH SCIENCES, INC. SGBh1-KE04!66BJ -Project.sl20040766IKE,WP Page 18 RosemonJ-Easr Re11to11 Property King County, Washington Subsu,face Exploration, Geologic Hazard, and Geotechnical Engineering Report Design Recommendations Permanent cut or fill slopes should not be steeper than 2H: IV where they are not exposed to surface water. Where slopes are exposed to surface water, such as within the detention pond, they should not be steeper than 3H: IV. -c--- 9 .2 Site Disturbance Most of the on-site soils contain substantial fine-grained material, which makes them moisture- sensitive and subject to disturbance when wet. The contractor must use care during site preparation and excavation operations so that the underlying soils are not softened. If disturbance occurs, the softened soils should be removed and the area brought to grade with structural fill. 9.3 Winter Construction Due to the high in situ moisture content of most of the site soils determined by laboratory testing completed for this study, it will be necessary to dry some of the site soils during favorable dry weather conditions to allow reuse in structural fill applications. If construction takes place in winter, drying is not expected to be feasible, and we anticipate that most of the lodgement till soils and potentially some of the outwash soils will be unsuitable for structural fill applications. Even during dry weather, site soils excavated for installation of buried utilities might not be suitable for utility backfill under paving or other structures. We recommend budgeting for backfill of buried utility trenches in structural areas with imported select structural fill. For summer construction, significant but unavoidable effort may be needed to scarify, aerate, and dry site soils that are above optimum moisture content to reduce moisture content prior to compaction in structural fill applications. Care should be taken to seal all earthwork areas during mass grading at the end of each workday by grading all · surfaces to drain and sealing them with a smooth-drum roller. Stockpiled s.oils that will be reused in structural fill applications should be covered whenever rain is possible. If winter construction is expected, crushed rock fill could be used to provide construction staging areas. The stripped snbgrade should be observed by the geotechnical engineer and should then be covered with a geotextile fabric such as Mirafi SOOX or equivalent. Once the fabric is placed, we recommend using a crushed rock fill layer at least 10 inches thick in areas where construction equipment will be used. If desired, planned roadways can be paved with asphalt treated base (ATB) for construction staging as described in the "Pavement Recommendations" section of this report. November 12, 2007 ASSOCIATED EARTH SCIENCES, INC. SGBhs -KE047668/ -ProjtCIS\200407661 KE\WP Page 19 Rosemoiu-East Renton Property King County, Washington 10.0 STRUCTURAL FILL Subswface Exploration, Geologic Hazard, and Geotechnical Engineering Repon Design Recommendations Significant structural fills are currently planned for this site. All references to structural fill in this report refer to subgrade preparation, fill type, placement, and compaction of materials as discussed in this section. If a percentage of compaction is specified under another section of this report, the value given in that section should be used. All structural fill placed on slopes steeper than SH: IV should be keyed and benched into suitable underlying native soils. Hillside benches should be 3 feet or less in height, and are usually about the width of the bulldozer used to cut them (about 6 to 8 feet). The shear key at the toe should be at least 8 feet wide and 3 feet deep. Keying and benching should be done in accordance with Washington State Department of Transportation (WSDOT) Standard Specification Section 2-03. 3. Site soils consisting of lodgement till or advance outwash or imported granular fill approved by the geotechnical engineer should be used for construction of fill slopes. The existing, uncontrolled fill soils identified near the northwest corner of the proposed development area should be completely removed prior to constructing any new structural fills or permanent cut slopes steeper than 3H:IV. After stripping, planned excavation, and any required overexcavation have been performed to the satisfaction of the geotechnical engineer/engineering geologist, the upper 12 inches of exposed ground should be recompacted to 90 percent of ASTM:D 1557. If the subgrade contains too much moisture, adequate recompaction may be difficult or impossible to obtain and should probably not be attempted. In lieu of recompaction, the area to receive fill should be blanketed with washed rock or quarry spalls to act as a capillary break between the new fill and the wet subgrade. Where the exposed ground remains soft and further overexcavation is impractical, placement of an engineering stabilization fabric may be necessary to prevent contamination of the free-draining layer by silt migration from below. After recompaction of the exposed ground is tested and approved, or a free-draining rock course is laid, structural fill may be placed to attain desired grades. Structural fill is defined as non-organic soil, acceptable to the geotechnical engineer, placed in maximum 8-inch loose lifts with each lift being compacted to 95 percent of ASTM:D 1557. In the case of roadway and utility trench filling, the backfill should be placed and compacted in accordance with King County codes and standards. The top of the compacted fill should extend horizontally outward a minimum distance of 3 feet beyond the location of the perimeter footings or roadway edges before sloping down at a maximum angle of 2H: IV. The contractor should note that any proposed fill soils must be evaluated by AES! prior to their use in fills. This would require that we have a sample of the material at least 72 hours in advance to perform a Proctor test and determine its field compaction standard. We have completed three such tests on representative samples of the site soils and the results are included in this report. Soils in which the amount of fine-grained material (smaller than the November 12, 2007 ASSOCIATED EARTH SCIENCES, INC. SGOIIS-KE047668/ -ProjtCU\20040766IKE\WP Page 20 Rosemont-East Renton Property · King County, Washington Subswface Exploration, Geologic Hazard, and Geotechnical Engineering Report Design Recommendations No. 200 sieve) is greater than approximately 5 percent (measured on the minus No. 4 sieve size) should be considered moisture-sensitive. Each of the three main soil types observed on- site, the recessional outwash, lodgment till, and advance outwash, all are estimated to contain more than 5 percent fine-grained material. Use of moisture-sensitive soil in structural fills should be limited to favorable dry weather and dry sub grade conditions. The on-site advance and recessional outwash deposits contain smaller amounts of silt and are considered suitable for use as fill material under a wider range of site and soil moisture conditions. The on-site lodgment till contains substantial amounts of silt and are considered highly moisture-sensitive when excavated and used as fill materials. At the time of our exploration program, soil moisture content tests indicated that some till soils encountered were at moisture conditions above optimum for structural fill use. We anticipate that most excavated lodgment till soils will require aeration and drying prior to compaction in structural fill applications. However, the outwash materials may be adequate for use as structural fill during summer months without significant aeration. Construction equipment traversing the site when the soils are wet can cause considerable disturbance. If fill is placed during wet weather or if proper compaction cannot be obtained, a select import material consisting of a clean, free-draining gravel and/or sand should be used. Free-draining fill consists of non-organic soil with the amount of fine-grained material limited to 5 percent by weight when measured on the minus No. 4 sieve fraction and at least 25 percent retained on the No. 4 sieve. 11.0 FOUNDATIONS Due to the presence of loose fill soil below the proposed buildings in portions of the site, we recommend that they be supported on a deep foundation system that bears on suitable, native soils at depth if the fill will not be removed during grading. We anticipate that deep foundation systems may be required in the vicinity of proposed Lots 75 through 80 or other areas when the existing fill is too deep to extend footings and stem wells and will not be removed. Conventional spread footings are anticipated for the remainder of the site, where existing fills are not present or are thin enough that foundations can be excavated to suitable bearing soil through the fill. It should be understood that unless all of the loose, existing fill is removed, the risk of slope instability and liquefaction (lateral spreading) will not be completely mitigated. However, the risk of these hazards affecting the new buildings is low if they are · founded in accordance with our recommendations. Table 2 presents depths to bearing soils for all explorations completed. We did not provide the bearing soil elevation because the locations of our exploration pits were not surveyed and assumed elevations may not be accurate. November 12, 2007 ASSOCIATED EARTH SCIENCES, INC. SGBIIJ-KEIJ4766BI -Pro}tcis\20040766\KE\WP Page 21 Rosemont-East Renton Property King County, Washington 11.1 Deep Foundations ... Table 2 Subswface Exploration, Geologic Hazard, and Geotechnical Engineering Report Design Recownendations Depth to Exploration Bearing Soil Pit (feet) Year -2007 EB-I 5.0 EB-2 5.0 EB-3 2.5 EP-1 2.0 EP-2 1.5 EP-3 3.0 EP-4 4.0 EP-5 3.0 EP-6 2.5 EP-7 2.5 EP-8 1.0 EP-9 1.0 EP-10 1.0 EP-11 1.0 EP-12 0.5 Year -2004 EP-2 I 2.5 EP-3 I 3.0 Year -2003 EP-11 8.0 EP-12 10.0 > EP-13 4.0 EP-14 1.0 EP-15 3.0 EP-16 0.5 EP-17 4.0 EP-18 2.0 EP-19 1.0 EP-20 1.0 EP-21 1.0 EP-22 1.0 Two alternatives for deep foundation systems are recommended. Rock trenches could be used in areas where existing fills are no greater than 8 feet deep. Pipe piles could be used where fills are deeper than 8 feet. November 12, 2007 ASSOCIATED EARTH SCIENCES, INC. SGDh! -KE04766BI -Projicu\20040766\KE\WP Page 22 · Rosemont-East Renton Property King County, Washington Pipe (Pin Piles) Subswface Exploration, Geologic Hazard, and Geotechnical Engineering Report Design Recommendations Small-diameter pipe (pin) piles consisting of thick walled, 4-inch-diameter, steel pipe driven by a hydraulic impact hammer mounted on an excavator or similar equipment are recommended. The 4-inch-diameter is recommended to add a degree of lateral support to the foundation system as piles will be located in moderately sloping fill soils. Pipes are typically provided in 10-foot sections and joined as needed with slip-or swage-fit couplers that are suitable for transmission of vertical compressive loads. Pipe type and schedule should be determined by the structural engineer for the project. Schedule 80 is typical for these piles. The pipe piles are driven until a suitable refusal criteria or penetration rate is achieved. The pipe piles are then incorporated into a system of pile caps and/or grade beams, which together act as the foundation system. The acceptable penetration rate (refusal criteria) depends on the driving equipment used. Four-inch nominal diameter, Schedule 80, galvanized-steel pipe piles driven to refusal at least 5 feet into the bearing soils should be capable of supporting loads on the order of 10 tons per pile. A refusal criteria of 16 seconds per inch is appropriate during sustained driving with a 850 foot-pound hydraulic hammer for 4-inch-diameter piles. · Different hammer sizes/types may have different driving characteristics and refusal criteria. If an alternate hammer is used, AES! should be notified prior to pile driving activities. We estimate the specified refusal criteria will be reached within 10 to 20 feet below existing ground surface based on our explorations and reconnaissance completed for the project. Resistance to lateral loads for a pipe pile-supported foundation would be provided by passive soil resistance against the grade beams, and, if necessary, using batter piles. A passive equivalent fluid equal to 150 pounds per cubic foot (pct) can be used for passive resistance to lateral loads on grade beams. Alternatively, if batter piles are used to resist lateral loads, the lateral resistance would be equal to the horizontal component of the axial pile load. The maximum recommended batter is 1H:4V. A structural engineer should determine the minimum spacing, location, and number of piles to be used. Pile Inspections The actual total length of each pile may be adjusted in the field based on required capacity and conditions encountered during driving and may be different than estimated above. Since completion of the pile takes place below ground, the judgment and experience of the geotechnical engineer or his field representative must be used as a basis for determining the required penetration and acceptability of each pile. Consequently, use of the presented capacities in the design requires that all piles be inspected by a qualified geotechnical engineering or engineering geologist from our firm who can interpret and collect the ) installation data and examine the contractor's operations. AES!, acting as the owner's field Novembtr 12, 2007 ASSOCIATED EARTH SCIENCES, INC. SGBhs -KE0476681 -Profects\200407661 KE\ WP Page 23 Rosemont-East Renton Property King Cowrty, Washington Subsurface Exploralion, Geologic Hazard. and Geotechnical Engineering Report Design RecommendaJions representative, would determine the required lengths of the piles and keep records of pertinent installation data. A final summary report would then be distributed following completion of pier or pile installation. As part of the foundation system design, a qualified structural engineer would determine the number of piles required and the minimum spacing between adjacent piles. We recommend that 10 percent of the piles, selected at random, be load tested to verify that the selected refusal criteria are appropriate, and that the assumed axial compressive capacity has been achieved. A dial gauge or other suitable instrument that is capable of measuring pile head displacements to 0.001 inch of accuracy should be used during load tests. Loads should be applied in increments of 25 percent of design load, beginning with 25 percent and . increasing to 150 percent. Each load should be held for at least 5 minutes, or until pile movement has stopped, at the discretion of the geotechnical engineer. The maximum load should be held for at least 15 minutes. Excessive displacement or creep of the pile during load testing are grounds for rejection of. the pile. Rejected piles may be spliced and re-driven, replaced, or assigned a lower allowable capacity. Pile installation and load tests should be performed by the contractor, and observed by AES! to record pile lengths, driving resistance, and load test performance. Rock Trenches In areas where the fill soils are considered too deep to economically extend the footings down to suitable bearing, but are less than 8 feet deep, rock trenches extended down to the medium dense to dense, natural soils can be used for foundation support. The trenches should have a minimum width of 4 feet (or as determined by the geotechnical ·engineer or his representative) and be excavated down to the medium dense to dense, natural soils. Because of the potential for caving, the actual trench width may be greater than specified. It would be appropriate to backfill the trenches as the excavation proceeds to reduce caving. The use of a larger, track-mounted backhoe will greatly speed trench excavation over the. use of a conventional rubber-tired backhoe. In order to reduce disturbance of the bearing soils exposed in the trench, we recommend that the teeth of the backhoe bucket be covered with a digging plate. To determine when su.itable bearing has been achieved and to verify proper rock placement, the AES! representative must be present on a full-time basis during rock trench excavation and backfill. A pump may be required to control seepage so that the bearing level can be visually determined. Seepage entering the excavation on an overnight basis must be removed prior to commencing trench excavation the following day. November 12, 2007 ASSOCIATED EARTH SCIENCES, INC. SGBhs ~ KE04766BI -Proj,msl200407661KE\WP Page 24 ) Rosemont-East Renton Property King County, Washington Subswface Exploration, Geologic Hazard, and Geotechnical Engineering Repon Design Recommendations After the bearing stratum has been reached, the trench should be immediately backfilled. We recommend the use of quarry spalls or 2-to 4-inch size crushed rock for backfill. The crushed rock must be tamped into place to achieve a tightly packed mass; this may be done with either a "Hoepac" type compactor mounted on tpe excavator or more typically, with the bucket of the excavator itself. Staging areas should be maintained so that that rock is not contaminated by mud prior to placement in the trench. Equipment access to trench locations should also be maintained. Spread footings may then be used for building support when placed over properly constructed rock trenches that bear on medium dense to dense, natural soils. Footings which bear on approved rock trenches may be designed for an allowable bearing pressure of 3,000 pounds per square foot (psf) including both dead and live loads. An increase of one-third may be used for short-term wind or seismic loading. However, all rock trenches must penetrate to the prescribed bearing stratum and no trenches should be founded in or above loose, organic, or existing fill soils. In addition, all footings must centered over the trenches and have a minimum of 14 inches for one-story structures, 16 inches for two-story structures, and j8 "inches for three-story structures. Anticipated settlement of footings founded on approved rock trenches should be on the order of I inch. However, disturbed material not removed from footing trenches prior to footing placement could result in increased settlements. All footing areas should be inspected by AES! prior to placing concrete to verify that the rock trenches are undisturbed and construction conforms with the recommendations contained in this report. Such inspections may be required by the governing municipality. Perimeter footing drains should be provided as discussed under the section on "Drainage Considerations." 11.2 Shallow Foundations In areas where existing fill is thin or absent, or where existing fill is removed and new structural fill pads are properly constructed, shallow spread footings may be utilized for building support when founded either directly on the medium dense to very dense, natural glacial sediments, or on structural fill placed over these materials. Natural sediments suitable · for foundation support were generally encountered in our explorations at depths of approximately 0.5 to 2 feet, except in those areas described above where existing fill occurred. For footings founded either directly upon the medium dense to dense, natural sediments or on structural fill placed over tl1ese materials, we recommend that an allowable foundation soil bearing pressure of 3,000 psf be utilized for design purposes, including both dead and live loads. An increase of one-third may be used for short-term wind or seismic loading. Perirneter footings for the proposed buildings should be buried a minimum of 18 inches into the surrounding soil for frost protection. Interior footings should be buried a minimum of 12 inches. All footings must penetrate to the prescribed stratum and no footings should be November /2, 2007 ASSOCIATED EARTH SCIENCES, INC. SGBlls-K£04766BI -Projecu\l00407661KEIWP Page 25 Rosemom-East Renton Property King County, Washington Subsurface Exploration, Geologic Hazard, and Geotechnical Engineerilig Report Design Recommendations founded in or above loose or organic soils. All footings should have a minimum width of 14 inches for one-story structures, 16 inches for two-story structures, or 18 inches for three-story structures. It should be noted that the area bounded by lines extending downward at lH: 1 V from any footing must not intersect another footing or intersect a filled area that has not been compacted to at least 95 percent of ASTM:D 1557. In addition, a l.5H:1V line extending down from any footing must not daylight because sloughing or raveling may eventually undermine the footing. Thus, footings should not be placed near the edge of steps or cuts in the bearing soils. Anticipated settlement of footings founded as .described above should be on the order of l4 inch. However, disturbed soil not removed from footing excavations prior to footing placement could result in increased settlements. All footing areas should be inspected by AES! prior to placing concrete to verify that the design bearing capacity of the soils has been attained and that construction conforms to the recommendations contained in this report. Such inspections may be required by King County. Perimeter footing drains should be provided as discussed under the section on "Drainage Considerations." 12.0 LATERAL WALL PRESSURES All backfill behind walls or around foundation units should be placed as per our recommendations for structural fill and as described in this section of the report. Horizontally backfilled walls that are free to yield laterally at least 0.1 percent of their height may be designed using an equivalent fluid equal to 35 pcf. Fully restrained, horizontally backfilled rigid walls that cannot yield should be designed for an equivalent fluid of 50 pcf. If roadways, parking areas, or other areas subject to vehicular traffic are adjacent to walls, a surcharge equivalent to 2 feet of soil should be added to the wall height in determining lateral design forces. Walls that retain sloping backfill at a maximum angle of 2H:1V should be designed using an equivalent fluid pressure of 55 pcf for yielding conditions or 75 pcf for fully restrained conditions. As required by the 2006 !BC, retaining wall design should include a seismic surcharge pressure in addition to the equivalent fluid pressures presented above. Considering the site soils and the recommended wall .backfill materials, we recommend a seismic surcharge pressure of 4H and 8H psf where H is the wall height in feet, for the "active" and "at-rest" loading conditions, respectfully. The seismic surcharge should be modeled as a rectangular distribution with the resultant applied at the mid-point of the wall. November 12, 2007 ASSOCIATED EARTH SCJENCES, INC. SGB/lr -KE04766BI -Projects\200407661 KE\WP Page 26 RosemonJ-East Renton Property King County, Washington Subswface Exploration, Geologic Hazard, and Geotechnical Engineering Repon Design Recommendations The lateral pressures presented above are based on the conditions of a uniform horizontal backfill consisting of the on-site, natural glacial sediments, or imported sand and gravel compacted to 90 percent of ASTM:D 1557. A higher degree of compaction is not recommended as this will increase the pressure acting on the wall. It is imperative that proper drainage be provided so that hydrostatic pressures do not develop against the walls. This would involve installation of a minimum I-foot-wide blanket drain to within I foot of finish grade for the full wall height using imported washed gravel against the walls. A prefabricated drainage mat is not an acceptable substitute for the gravel blanket drain. 12.1 Passive Resistance and Friction Factors Lateral loads can be resisted by friction between the foundation and the natural glacial soils or supporting structural fill soils, or by passive earth pressure acting on the.buried portions of the foundations. The foundations must be backfilled with structural fill and compacted to at least 95 percent of the maximum dry density to achieve the passive resistance provided below. We recommend the following design parameters: o Passive equivalent fluid = 250 pcf • Coefficient of friction = 0.35 The above values are allowable and include a safely factor of at least 1.5. 13.0 FLOOR SUPPORT Concrete, slab-on-grade floors may be used for the new buildings where the slabs are underlain by dense, natural soils or structural fill. We recommend crawl spaces and structural floors be used where foundations are supported on piles or rock trenches. If crawl space floors are used, an impervious moisture barrier should be provided above the soil surface within the crawl space. Slab-on-grade floors should be cast atop a minimum of 4 inches of pea gravel or washed crushed rock to act as a capillary break. The floors should also be protected from dampness by covering the capillary break layer with an impervious moisture barrier at least IO mils in thickness. Floor slabs that are supported by site soils prepared in accordance with the "Site Preparation" section of this report or by structural fill should experience 1/z inch or less of settlement. November 12, 2007 ASSOCIATED EARTH SCIENCES, INC. SOB/ls-KE04766BJ -Projws\20040166IKE1WP Page 27 Rosemom-East Renton Property King County, Washington 14.0 DRAINAGE CONSIDERATIONS Subsiuface Exploration, Geologic Hazard, and Geotechnical Engineering Repon Design Recommendations All footing walls, basement walls, and retaining walls should be provided with a drain at the footing elevation. Drains should consist of rigid, perforated, polyvinyl chloride (PVC) pipe surrounded by washed pea gravel. The level of the perforations in the pipe should be set at tlie bottom of the footing at all locations and the drain collectors should be constructed with sufficient gradient to allow gravity discharge away from the buildings. In addition, all foundation walls taller than 3 feet should be lined with a minimum, 12-inch-thick, washed gravel blanket provided to within I foot of finish grade that ties into the footing drain. Roof and surface runoff should not discharge into the footing drain system, but should be handled by a separate, rigid, tightline drain. In planning, exterior grades adjacent to foundations should be sloped downward away from the structures to achieve surface drainage. 15.0 PAVEMENT RECOMMENDATIONS Undocumented fill materials underlie portions of the proposed improvement area. The quality of these materials was variable and observed to be relatively loose. As such, some remedial measures will be necessary for support of pavement in fill areas. We recommend that new pavement sections (including gravel base and top courses) in existing fill areas be underlain by at least 2 feet of structural fill compacted to at least 95 percent of ASTM: D 1557. The King County standard paving section for residential access streets is 2 inches of Class B asphalt concrete paving (ACP) above 4 inches of A TB. Although it is not required by King County, we recommend that ATB be placed above a 2-inch-thick layer of crushed surfacing top course (WSDOT Standard Specification 9-03.9(3]). An alternative section is 2 inches of ACP above 1.5 inches· of crushed surfacing top course above 5 inches of crushed surfacing base course (WSDOT 9-03.9(3]). All depths given are compacted depths. All paving materials, base course materials, and placement procedures should comply with suitable standard specifications, such as the Washington State Department of Transportation (WSDOT) Standard Specifications for Road, Bridge, and Municipal Construction or other suitable specifications. We understand that a pavement analysis is required for frontage improvements to 148111 Avenue SE. Soil conditions on this site are virtually identical to those documented to the south on CamWest's Shamrock Nursery development, at least adjacent to 148'" Avenue SE. Therefore, in our opinion, the pavement analysis AES! completed in 2004 is adequate for design of the new frontage improvements associated with this project. The 2004 pavement analysis and design pavement sections are included as Appendix B to this report. November 12, 2007 ASSOCIATED EARTH SCIENCES, INC. SOB/ls -KE047668J -Projtcts\20040766\KElWP Page 28 Rosemont-East Rl!mon Property King Cow,ry, Washington 16.0 INFILTRATION POTENTIAL Subsw.face Er:ploraJion, Geologic Hazard, and Geoteclmical Engineering Report Design Recommendations The site's infiltration potential is considered to be low due the presence of a shallow ground water table and rather widespread, underlying, relatively impermeable lodgement till soils. There are small deposits of highly permeable recessional outwash and advance outwash on the site, but these deposits often contained considerable ground water and were limited in extent. Therefore, in our opinion, storm water detention is the most appropriate storm water management strategy for the s.ite. 17.0 DETENTION FACILITIES Two detention facilities are planned for the site. A detention pond is planned for the northeast corner of the northern parcel and a vault is planned near the northwest corner of the southern parcel. The current grading plan shows the base of the detention vault at Elevation 446.0. Since the location of EB-I was not surveyed, we are unsure if the base of the vault will be excavated into till or advance outwash. If outwash is encountered, the vault should be lined as discussed below for the detention pond. There appears to be at least 8 feet of separation between the proposed vault bottom elevation and current ground water elevation. However, the contractor should be prepared to de-water the excavation, if necessary. The vault foundations can be designed for an allowable foundation soil bearing pressure of 5,000 psf, including both dead and live loads. An increase of one-third may be used for short- term wind or seismic loading. The "Lateral Wall Pressures" section of this report should be referred to for detention pond cast-in-place retaining wall design. Based on the current grading plans, the construction of the pond will entail excavation to the desired pond bottom elevation and construction of perimeter fill berms along the northwest portions of the pond, transitioning to cut slopes along the southwest pond walls.. Fill berm heights .are expected to be on the order of 15 feet. With pond berm heights greater than 6 feet, the impoundment facility must comply with requirements for dam safety (WAC 173-175) if the storage capacity is greater than JO acre-feet above natural ground level. The pond will be excavated into till on the east and advance outwash sand on the. west, based on the soils encountered in EB-2 and EB-3. Ground water is expected to occur approximately 10 feet below the proposed base of pond elevation, as shown on Figure 3. Water stored in the pond without any form of liner would most likely migrate through the soil into the wetlands west of the pond location. A soil liner meeting the below-mentioned fill embankment specifications or a geosynthetic liner is recommended to reduce the amount of water migration through the underlying advance outwash sand. At this location, advance outwash exposed in excavations may be prone to raveling and as such the inner pond sidewalls should be graded to no steeper than 3H: 1 V. Exterior sides of the pond embankments November 12, 2007 ASSOCIATED EARTH SCIENCES, INC. SGBlu-KE0,4766BI -Pmjuut:!D04'0766IKE\WP Page 29 Rosemoiu-East Remo11 Property King County, Washington Subsu,jace Exploration, Geologic Hazard, and Geotechnical Engineering Report Design Recommendations may be graded no steeper than 2H: IV unless existing fill soils are encountered within the external pond berm area. Berm construction should be entirely of properly compacted structural fill. Liner type, size, and installation should conform to the manufacturer's recommendations. Preparation for placement of structural fill for detention pond berm construction will entail excavation of the proposed fill area to firm, stable subsoil, as described in the "Site Preparation" section of this report. Perimeter pond berms should have a minimum top width of 6 feet if the berm will not be used as a perimeter roadway. Berms that will be used as access roadways should be 12 feet wide along straight sections and 15 feet wi~e at curves, at a minimum. A key equal to the berm width and a minimum of 3 feet deep (and extending down to medium dense, native soils) should extend below the. base of the pond berm. The pond should also be equipped with an emergency overflow system that is connected to a suitable storm water disposal facility. The pond should be designed and constructed in accordance with the current KCSWDM. Fill soils for detention pond berm construction should contain a maximum of 60 percent sand, with a minimum of 30 percent silt, and nominal gravel and cobble content. The on-site till soils encountered in EB-3 meet this gradation requirement based on one sieve analysis we performed on this material. Additional sieve analyses of the proposed berm and liner fill will be required prior to construction. The fill should be placed as structural fill with a moisture content at or up to 2 percent above the optimum moisture content for compaction. The fill should be compacted by a sheepsfoot roller to a minimum of 95 percent of the ASTM:D 1557 maximum dry density, as described in the "Structural _Fill" and "Site Preparation" sections of this report. Due to their high silt content, compaction of fill soils meeting the stated specification may be difficult to achieve during wet weather. In addition, persistent ground water seepage associated with flow to the adjacent wetland to the west may be encountered during berm keyway construction. Therefore, the keyway excavation may require specialized stabilization techniques in this location depending on the time of year and quantity of ground water encountered. The gradation of all detention pond berm and soil liner fill should be verified by AES! prior to its use, using appropriate laboratory testing. Keyway and berm construction and compaction should be observed and tested by the geotechnical engineer's representative. 18.0 ROCKERIES At least two short rockeries are plarmed along the south property line to complete grade transitions. Rockeries may be used to prevent erosion of cut slopes, however, they are not engineered structures and we strongly suggest that they not be used in place of retaining walls, especially where important facilities are adjacent to them. Buildings should be set back from rockeries so that a !H: IV line extending up from the rear base of the rockery does not intersect November I 2, 2007 ASSOCIATED EARTH SCIENCES, INC .. SGS/ts-KE04766BJ -Pro}tcul10040766IKE1WP Page 30 Rosemont-East Renton Property King County, Washington Subswface Exploration. Geologic Hazard, and Geotec/mical Engineering R_epol1 Design Recommendations the footing. Rockery construction is an art that depends largely on the skill of the builder. We would like to point out that although rnckeries are commonly used, they occasionally have difficulties and should be considered a long-term maintenance item. Care must be exercised in selecting a rock source since some of the material presently being supplied is soft and disintegrates in a relatively short period of time. Samples of rock can be tested by AESI prior to their use in rockeries. If a rockery is specified, 4 feet high or less, it usually will not require a permit. Rockeries should not face fill soils greater than 3 feet in height. The following notes present rockery considerations. In addition, the contractor should confirm that his configuration conforms to current King County specifications. A. The base of the rockery should be started by excavating a trench to a minimum depth of 36 inches below subgrade into firm, undisturbed ground. This trench should extend a minimum of 2 feet in each direction beyond the base rocks. The trench should be backfilled to a depth of 12 inches below existing site grade with free-draining sand and gravel or crushed rock. If loose, soft, or disturbed materials exist at the base of the trench, they should be removed and replaced with free- draining sand and gravel or crushed rock. This backfill material should be placed in lifts not exceeding 8 inches in loose thickness and compacted to a minimum of 95 percent of the modified Proctor maximum density using ASTM:D 1557 as the standard. The gradation of the sand and gravel should be such that of the material passing the No. 4 sieve, not more than 5 percent by weight should be finer than the No. 200 sieve. B. The base rock should have a mmunum width (perpendicular to the line of the rockery) of 40 percent of the height of the rockery and should be centered upon the zone of compacted structural fill. All rocks should also meet the following weight requirements: Height of Rockery Above 5 feet 5 feet or less Minimum Weight of Rock 500/2,200 pounds, graded, top/bottom _rocks 500/1,000 pounds, graded, top/bottom rocks C. The rock material should all be as nearly rectangular as possible. No· stone should be used which does not extend through the wall. The rock material should be hard, sound, durable, and free from weathered portions, seams, cracks or other defects. The rock density should be a minimum of 160 pcf. D. Rock selection and placement should be such that there will be minimum voids and, in the exposed face of the wall, no open voids over 8 inches across in any direction. The rocks should be placed in a manner such that the longitudinal axis of the rock will be at right angles or perpendicular to the rockery face. Each rock should be November 12, 2007 ASSOCIATED EARTH SCIENCES, INC. SGBl1s -KE0476681 -Projwsl20040766IKE.\WP Page 31 Rosemont-East Re/lion Property King County, Washington Subswface Exploration, Geologic Hazard, and Geotechnical Engineering Report Design Recommendations placed so as to lock into two rocks in the lower tier. After setting each rock course, all voids between the rocks should be chinked on the back with quarry rock to eliminate any void sufficient to pass a 2-inch square probe. The rockery should be limited to 8 feet in height. E. A drain consisting of rigid, perforated, PVC pipe enclosed in a 12-inch-wide, pea gravel trench should b~ placed behind the lower course of rock to remove water and prevent the build up of hydrostatic pressure behind the wall. The remainder of the wall backfill should consist of quarry spalls with a maximum size of 4 inches and a minimum size of 2 inches. This material should be placed to a 12-inch minimum thickness between the entire wall and the cut material. The backfill material should be placed in lifts to an elevation approximately 6 inches below the top of each course of rocks as they are placed, until the uppermost course is placed. Any backfill material falling onto the bearing surface of a rock course should be removed before the setting of the next course. F. Any asphalt paving should be sloped to drain away from the rockery. In addition, the areas above rockeries should be planted with grass as soon as possible after rockery construction to reduce erosion. 19.0 PROJECT DESIGN AND CONSTRUCTION MONITORING We are available to provide geotechnical consultation as the project design develops. We recommend that AES! perform a geotechnical review of the plans prior to final design completion. In this way, our earthwork and foundation recommendations may be properly interpreted and implemented in the design. This review is not included in our current scope of work and budget. We are also available to provide geotechnical engineering and monitoring services during construction. The integrity of the foundation depends on proper site preparation and construction procedures. In addition, engineering decisions may have to be made in the field in the event that variations in subsurface conditions become apparent. Construction monitoring services are not part of this current scope of work. If these services are desired, please let us know and we will prepare a proposal. November 12, 2007 ASSOCIATED EARTH SCIENCES, ENC. SGBhs -KE0476681 -Pro}tm\20040766IKli\WP Page 32 Rosemont-East Remon Prope,ty King County, Washington Subswface Exploration, Geologic Hazard, and Geotechnical Engineering Report Design Recommendations We have enjoyed working with you on this study and are confident that these recommendations will aid in the successful completion of your project. If you should have any questions, or require further assistance, please do not hesitate to call. Sincerely, ASSOCIATED EARTH SCIENCES, INC. Kirkland, Washington -~[U, Jj QU,/clzfWY\- Susan G. Beckham, P.E. Senior Project Engineer Curtis J. Koger, P.G., P.E.G, P.Hg. Principal Geologist/Hydrogeologist Attachments: Figure 1: Figure 2: Figure 3: Vicinity Map Site and Exploration Plan Geologic Cross Section A-A' Kurt D. Merriman, P.E. Principal Engineer Appendix A: Appendix B: Exploration Logs and Laboratory Testing Results Pavement Section Recommendations for 148th Avenue SE November 12, 2007 ASSOCIATED EARTH SCIENCES, INC. SGBitt -KE04766Bl -Pro},cts\20040766(KE\WP Page 33 il I Ji! ~ f~'~{~t'.:. :.:. !(.:. •h :.~ l(,:-. /·, " ;fr I• " I -~--. . .~. . . . ~:. I_---! .·:...:......!..' rl .... Ec;..::· ~ ·-C --; •. -. ·i, ti \ rl ... , I= "'1 .lA = 1J~ ~J..a< ~t·' --~,, li,/' ... '"\""-7 '( ' \}.,. :-.:. L:i._J:.<' iH ·1 .. :.;f .•' I.~ ~-.. /' ;)./ ,.,. \Jf)l '. ~i::,::·;,::, i\ . •. ·-;,,. t \ ' ~·;c~'.i1 b ,,,. i= '~-,. . ,, \ ··. tl ~,, ·...:;_·., -~ ;~~}\:/1' \ 1 ] .. ~~HI \! ('.:!:. ! <'C:,! ·,-•'f •: '·'-,;:"" ';~ \, ___ !H'.;F:l ···---~~-__L.:_r ------', .. ',, ' / ;:;lt.J ·-1•.J C: '~~~--.:'' ,._~/~_ i;,: :.c I \ ~.'~~1t~~ ... ''-·o·, I -::· -~j (' \ ·, . i:.: \.~\ \); "\-~ \ \ ···,'.f.it,-1 .. ·,._2 __ z !1!_ Ii -~~;:<_ / ·--.,. ~-~~-__ :..---~ :r:~·'.•'j __ ._..,};·-,. ? __ ~,~ .. ___ ,. fl.,:f ! .. //, ____ ,. .·.i /...#'-~;.-_,. 7-·· _f.§rl L-· ::~; ,; ,1 ~i lif:U ~: l l u r_.!1 ';!: lUlll ·---, ' :;;,r, ·''! ,a.i er r:// Jf, l "; -~ :."· j_ :1 ,, ! < \"'; ,:,_Ill --j-·' ~ ,,--;f{_ "" --'-'---cil ;: :;c -~ t====,~, -~~ :JI-- ;-_: F.y· ' ; ;fl ~-! i ~- I N A 71' .... i ,u, \':;,0_j;'.I ~ .>I. NO SCALE "' : ~~ :.(•.•111 :'~·· !; Ti~·: : ... :.. !.~•.•:c1,11_-'--~- z .. :•.' !H 1, 1= I· I"· Cl;,:::_--;:::., :, :.-:.>: ·1 ' T ~J-J. i .::...J~J~_! .:L-n! ~·_!'0 ·_ .. :L i~; ~J.~-£..-:-'.7.;I::,&'! i:4,\'tV.cki' ,o:_,ffid'/?'i'<::i0-.'!.¥,\'1 _,;.,..,,,.· I, ~~A-,>-·--,,_ j:,:,<, ___ • ,,..,.. -·="'~ _,,.,.,..,, - Associated Earth Sciences, Inc. VICINITY MAP .',c , __ :[ .. ,/.'.ID----.. "'::, FIGURE 1 DATE 11/07 ~ ~ ~ ~ ~ ROSEMONT EAST RENTON PROJECTS ~ ~ ~ Jel tmi KING COUNTY, WASHINGTON PROJ. NO. KE040 7666 ; l ! l ! ; I jg]f :~-~--:,, l , 1 : '>-1,,, , ''" ~~~~:{··<C"~t~',>\ V -<c.;,/i/ t -I l I~ ' , , , ' • , I ' ; / /, if ', ,_i ROSEMONT PROPER) t , , ' ', '. • 't· ,·--, ' '.,. .... \", '' (FORIIERLYIRONWOO } r,t •. 1'-.!i , ", I : ... , '!I:·'\ ,-.. ',_ ft;iJ#' EAST RENTON PROPERTY 1 ' -:-:::.,-.~. (FORMERLY ROSEMONl) !'a .. ~-: ·, '.t--·'.,.,..;,· ,, ....... I -, ',_....;t ... ..-v ' ' _.,I ,, ,, -,-17 '=~ ,~-,-.\--\;~:_;:) f ·. I ,~J~-:\ ' .['\ i ·,~ : ' ' ' ' ·--~----'-, -----------------------t-------------------------------------------------------------------j1 ' ' ' ' ' ' ' ' Reference: Triad l Associated Earth Sciences, Inc. SITE AND EXPLORATION PLAN • '{\_ ., ·' "'"--~-.-;;,~_,,._ LEGEND: 0 APPROXIMATE LOCATION OF BORING BY AES! 10/1007 TYP D APPROXIMATE LOCATION OF EXPLORATION PIT BY AESI 8/2007 TYP A APPROXIMATE LOCATION OF EXPLORATION PIT BY AES! 12/2004 TYP 0 APPROXIIIA TE LOCATION OF EXPLORATION PIT BY AESI 412003 C2:) EXISTING ALL WITH APPROXIMATE DEPTH 1~~,···"j Qva ADVANCE OUlWASH c::J Qv~ RECESSIONAL OUTWASH = Qvt TILL I;;) NL ¥ ID NP sell.-~ t'i €"P~'2..~ S§ I b-to{; S OON'i 6't!. re,Vl) Pt, WAI Tb P Otllf> !'.!,!Tr. ,.l I I.. t ,V(:t(? t;dJ/,_f> D!' p"'"""9 Pf(. <.iiLcN,-l;'(H,_o N A I -~ = FIGURE 2 DATE 11/0i s M lm@g filPI ~ ~ ROSEMONT EAST RENTON PROJECTS i ~ B;I ~ C!i.11 ~ KING COUNTY, WASHINGTON PROJECT NO. KE0407666 ·-----==--=:::...:=:.....:=...::::.=--,---------------------------------------'-""='-;cc.c-=c..;ccc.c.._ l l ! ie ~ A 490 iii w 470 ~ z 0 i 450 w 430 410 390 Recessional outwash (silt) -- BEARING FOR KEY AT DEPTH 5' 0 ., HORIZONTAL DISTANCE (FEET) VERTICAL EXAGGERATION = 2x g EXISTING GRADE\ Advance outwash(sand) 0 ;;; ~ 1711 - INTERIQR POND BERMS FLATTEN TO 3H: 1V MAX -------- Csilt ?~ ~ -=- 0 0 ... 0 ., ... Associated Earth Sciences, Inc. GEOLOGIC SECTION A -A' A' 490 470 450 430 410 390 FIGURE 3 ~ 1,~1 ~ ~ M ROSEMONT EAST RENTON PROJECTS DATE 11/07 ~ . . ~ ~ , KING COUNTY, WASHINGTON PROJECT NO. KE040766B 500 '"' - .,. .... ... "" 430 '20 I i : I I ~ -• B ( ~ ~ ~ ARMOUR EXlB"OR PONO BERMS WITH12"0Fbf" QUARRY SPALL RrPRAP PR<POSED AN/SH G.'?ADE (;yp) \ '\. ,- GRA\ICL ACCESS ROAD/BERM - 60 Mil PVC lEXTURED LINER V't'ITH 12" SOil COVER EXISTING GROUND (iYP} INTERCEPTOR TRENCH SEEAGURE2 NEW SLOPE ALL KEYWAYAND BENCHES-TYP Dll'S EL 1SJ.IXJ -----~ ·-·~··· ,.._j ----~--_\ ~· .·, --!:!:VdOC4'iffL 4~.0Q. ----?\ ----------- -INTERNAL SIDE Sl.OPES SHALL -----BOT El. 442.0 BE 3: I 6fiOW ELEV 458.0 . · · (EXCEPT FOR THE SERIJ --BETJliffN CELLS}. ""' NEW SI.OPE FILL t<EYWA Y ANO BENCHES LOW PERMEABIUTY STRUCT1JRAl. FILL· lYP SEE GEOTECHNICA.L REPORT B 500 I ~ • ~ f-'" g a ~ f-"' • ; w 6Fl"' - . . .. "" .... • I "" "" L..---,---,---,-,-----,---,---,---,-----,----,---,-----.---.---.---.-----.-_J ~ HORIZOrlfAL DISTANCE (FEET) VERTICAL EXAGGER,t.TlON • 1x ~ " • • Qw VASHONRECESSIONALOUTWASH-SILT ""' VASHON LODGMENT TIU-LOW PERMEABILITY a-VASHON ADVANCE OlJTWASH • SANO ~ ' ! -i 8 ~ ~ g 8 .-N N N N <'> ! POND SECTION B-8 --ASSUMED BEARING SOIL· ELEVATION BASED ON EXPLORATION BORINGS • APPROXIMATE GROUNDW'ATER DEPTH AT TIME OF ORIWNG -?-1-GEOLOGIC CONTACT ~ _ _,.;.:,.-~-~ .;_.-~ef-~,.;_:~ 'I : ... fltrD tt. EXPIIES 11/20/t:e '=========================================== I AssociatedEarthSciences,lnc. GEOLOGIC CROSS-SECTION B • B "0 ""e' : ratiil ~ ~ ~ iiiJ£il ROSEMONT-EASTRENTONPROPERTY DATE 210a · I em e:gi ~ lllill Biiil KING cauNTY. wAsHINGToN PROJECT No KE0407668 z :ii lo MIN 4' DIA PERFORATED RIGID PVC PIPE WITH PERFORATIONS SET DOWN PROVIDE MIN 1% CONTINUOUS SLOPE TO APPROVED OUTLET , .ssociated Earth Sciences, Inc. 12" MINIMUM I ,--,, ~ 12· J I• OVERLAP I ORIGINAL GROUND SURFACE WASHED DRAIN ROCK FILTER FABRIC MIRAFl-140N OR EQUIVALENT WRAP ENTIRE DRAIN WASHED DRAIN ROCK Fill I Weathered Till Gray. Non-Weatherad Till TYPICAL INTERCEPTOR TRENCH DETAIL ROSEMONT-EAST RENTON PROPERTY 'KING COUNTY, WASHINGTON FIGURE 2 DATE 2/08 PROJ. NO. KE040766A APPENDIX A Exploration. 1Logs an.di ]Laboratory Testing Results ~- Well-graded gravel and GW gravel with sand, little to no fines Poorly-graded gravel and gravel with sand, little to no fines Clayey gravel and GC clayey gravel with sand Well-graded sand and sw sand wilh gravel, liltle to no fines Poorly-graded sand SP and sand with gravel, little to no fines Silly sand and SM silty sand with gravel Clayey sand and clayey sand with gravel Terms Describing Relative Density and Consistency Coarse- Grained Soils Density SPT(~blows/foot Very Loose · 0 to 4 Loose 4 to 10 Medium Dense 1 O to 30 · Dense 30 to 50 Very Dense > 50 Test Symbols G = Grain Size Consistency SPT121blows/foot M = Moisture Content A "" Atterberg Limits C = Chemical Fine· Grained Soils Very Soft O to 2 Soft 2to4 Medium Stiff 4 to B Stiff 8lo15 Very Stiff 15 to 30 Hard >30 DD = Dry Density K = Permeability Descriptive Term Bouldets Component Definitions Size Range and Sieve Number Larger than 12" Cobbles Gravel Coarse Gravel Fine Gravel Sand Coarse Sand Medium Sand Fine Sand Slit and Clay 3"10 12· 3"to No. 4 (4.75 mm) :r to 3/4" 3M-to No. 4 (4.75 mm) No. 4 (4.75 mm) to No. 200 (0.075 mm) No. 4 (4. 75 mm) to No. 1 O (2.00 mm) No. 10 (2.00 mm) to No. 40 (0.425 mm) No 40 (0.425 mm) to No. 200 (0.075 mm) Smaller than No. 200 (0.075 mm) (3 ) Estimated Percentage Component '--l--'-l\~tll--+-------1 Trace Percentage by Weight <5 Moisture Content Dry· Absence of moisture, dusty, dry to the touch S1lghtly Moist -Perceptible molslure Sill, sandy sill, gravelly sill, ML silt with sand or gravel Clay of low to medium plaslicily; silty, sandy, or gravelly clay, lean clay Organic clay or sill of low plasticity Few little With Sampler Type laslic sill, clayey sill, silt 2.o• 00 MH with micaceous or S I s diatomaceous fine sand or pl I· poon Sampler __ sil,,_I --------! (SPT) 51010 15 to 25 -Non-primary coarse consllluenls: ?,_ 15% -Fines con\enl between 5% and 15% Moisl • Damp bul no visible water Very Moist • Water visible but not free draining Wet. Visible free water, usually from below water !able Symbols Blows/6• or portion ol s• I • • • Sampler Type DescrlpUon 3.0" OD Split-Spoon Sampler 3.2s· OD Split-Spoon Ring Sampler ,., Cement groul surface seal Ben1onile ,eal Clay of high plasticity, sandy or gravelly clay, fat Bulk sample 3.0" OD lhln-Wall Tube Sampler ~ncludlng Shelby tube) :. Filter pack with :·; blank casing :-· seclion :.-Screened casing . •• or Hydrollp clay with sand or gravel Organic clay or silt of OH medium to high plaslicity o Portion not recovered Standard Practice for Descriplion and ldenlificallon of Solis (ASTM 0>2488) ·: with filler pack ·• End cap l4l Depth of ground waler i. ATD = At lime or drilling Sl. Static waler level (date) (5} Combined USCS symbols used for fines bet-Neen 5% and 15% l Classmcellons of solls In this report are based on vlsual neld and/or laboratory observations, which Include denslly/conslslancy, moisture condiUon, grain size, and plasllclly es\lmales and should not be construed to Imply fleld or laboratory tasUng unless prasenled herein. Vlsual-manual and/or laboratory classlncallon ~ melhods of ASTM 0-2487 and 0-2488 were used as an ldentiflcatlon guide for lhe Unified soa Classlncatlon System. 1; Associated Earth Sciences, Inc. i' . ,· . 1lfll~lilRII EXPLORATION LOG KEY FIGURE A1 1 - 2 3 - LOG OF EXPLORATION PIT NO. EP-1 This log is part of the report prepared by Associated Earth Sciences, Inc. (AESI) for the named project and should be read together with that report for complete interpretation. This summary applies only to the localion of this trench at the time of excavation. Subsurface conditions may change at this location with the passage of time. The data presented are a simplflcation of actual conditions encountered. DESCRIPTION Brush and Topsoil Organic FIii Moist to dry, dark brown, silty fine to medium SAND, with gravel and roots and organics. (SM) Vashon Lodgement Till Medium dense grading to dense at 3 feet, moist, mottled brown-gray, silty fine to medium SAND, with gravel and cobbles; gray and very dense with no mottling below 3.5 feet. (SM) 4-l----------------------------------- 5 - 6 - 7 - 8 - 9 - 10 - 11 - 12 - 13 - 14 - 15 - 16 - 17 - 18 - 19 - Bottom of exploration pit at depth 4 feet No ground water. No caving. ~-----;<&---------------------- .., I Rosemont-East Renton Property. King County, WA ~ Associated Earth Sciences, Inc. I Logged by: SGB Project No. KE040766B ~ Approved by [ti I ~I ~ a II 7/16/07 ~----------------------------------------------- 1 - 2 - 3 - 4 - LOG OF EXPLORATION PIT NO. EP-2 This log is part of the report prepared by Associated Earth Sciences, Inc. (AESI) for the named project and should be read tqgether with that report for complete interpretation. Thls summary applies only to the location of this trench at the time of excavation. Subsurface conditions may change at this location with the passage of time. The data presented are a slmplfication of actual conditions encountered. DESCRIPTION Brush and Topsoil FIii Medium dense, dry, dark brown, silty SAND, with organics and roots. (SM) Weathered Vashon Lodgment TIii Medium dense, moist to dry, brown, silty fine SAND, with gravel, cobbles, few roots, little cohesion. Vashon Lodgement TIii 5 -Very dense, moist, gray, silty fine to medium SAND, with gravel and cobbles. (SM) 6 7 - 8 - 9 - 10 - 11 - 12 - 13 - 14 - 15 - 16 - 17 - 18 - 19 - Bottom of exploration pit at depth 6 feet No ground water. No caving. ~-~---------------------- "' I Rosemont-East Renton Property King County, WA & : Associated Earth Sciences, Inc. Project No. KE040766B ~ Logged by: SGB Approved by [M 1-~1 ~ Iii] I! 7/16/07 ~--------------------- LOG OF EXPLORATION PIT NO. EP-3 This log ls part of the report prepared by Associated Earth Sciences, Inc. (AESI) for the named project and should be read together with that report for complete interpretation. This summary applles only to the locallon of this trench at the lime of excavation. Subsurface conditions may change at thls locatlon with the passage of time. The data presented are a simplficetlon of actual conditions encountered DESCRIPTION Brush and Topsoil 1 -Weathered Vashon Lodgement TIii Loose, moist, dry, brown, silty fine SAND, with gravel, cobbles, and roots. (SM) 2 - 3-+--------------~~~~-~-~=~--------------Vashon Lodgement TIii Dense to very dense, moist, gray, silty fine to medium SAND, with gravel and cobbles. (SM) 4 - 5 - 6 7 - 8 - 9 - 10 - 11 - 12 - 13 - 14 - 15 - 16 - 17 - 18 - 19 - Bottom of exploration plt at depth 6 feet No ground water. No caving. ~-29----'---------------------- "' l Rosemont-East Renton Property King County, WA ~ Associated Earth Sciences, Inc. ffl Logged by: SGB Project No. KE040766B ~ Approved by IJll I ~\\ ~ liil [II 7/15/07 ~----------------------- LOG OF EXPLORATION PIT NO. EP-4 g This log is part of the report Jrepared by Associated Earth Sciences, Inc. (AESI) for the named ftroject and should be a read together with that repo for com~lete lnlerpretalion. This summary a~plles only to the loca Ion of this trench at the time of excavation. Subsurtace condl Ions may change at this locatlon wit the passage of lime. The data presented are ~ a slmplficatlon of actual conditions encountered. · DESCRIPTION Brush and Topsoil 1 -Colluvlum Loose to medium dense, dry, brown, silty fine to medium SAND, with gravel, cobbles, roots, trace 2 -boulders. (SM) 3 - 4 Recessional Outwash 5 Medium dense, moist to dry, stratified SAND, with gravel and abundant roots. (SP) 6 -Medium dense, moist, fine to medium SAND, with silt and gravel and interbeds of silty medium to coarse SAND. (SP-SM) 7 - 8 - 9 - 10 -Becomes wet at 1 O feet. 11 - 12 Medium dense, wet, gray, medium to coarse SAND, with silt, cobbles, and gravel. (SP-SM) 13 Pre-Fraser Sedimentary Deposits (Qpf) 14 Stiff to hard, dark brown, PEAT, with gray and brown, hard silt interbeds. (PT/ML) 15 - Bottom of exploration pit at depth 14 feet Very slow ground water seepage at 10 feet. Moderate caving 5 to 13 feet. 16 - 17 - 18 - 19 - i--z&-------------------------- " i Rosemont-East Renton Property King County, WA I ~=~:~Y~YSGB ;cir; 1 E;5c;es. Project No. KEO:~~::~ ~------------------- Associated Earth Sciences, Inc. JobFile 0 Calculation .W 9 I I Fifth Avenue, Suite I 00 Kirkland.WA 9803) DISTRIBUTION: ---------- 42S 827-7701 FAX 425 827-5424 Incoming Call D Outgoing Call O FIie 0 Phone Log o· Memo D Conference D Info D Date ?{); 8 /o r./ I ' Project No. /<fo l:,;C;'?'{..---c, Project 0 h .f?t#/lt('tJt./c> · · Subject _-1-LL---------------- Person/Company ------------~--- Phone No. ------~--Page '2--of 2- c;i 0, "SN,jc.., :::. ct, D, ~ ( 'ft/)( 1 ~---v;:,.f ) " I . 7 lo •· o-f;_, 1/ 5e. ·?"' ;,• ,,..r~-:-... .. f) /1 .. c ..... t .. { ;::;-·s."-17.. .. I./ 5 e -r;, ,,. .... \· ~ / C. I" t,''.3 f...-12. t:( /( 0 C ./c.. ---------·-·------ 5f'J, -(SN,'" -r SJV;(.") C• ··I iYl3 = /,7--2,'iJ :2, 7 -( 2, 'Iii? -/. 7(:,) (OJ1)(0.i) .-· •'/ rs< 2:2...~ .'/ ----···_;· __ .•' ,•, ·'·/, !_ .,,, •• ' .-' (;J .• _., . ----·-~-. --·--··------· ----------µ_ t -_b V ,, ,4-r6 ---:,, b,; 1/rj rVLe ti.I) J .fell !l-r8 '-t,s'µ//1'~r8 (Jq I),) -t :··et "'l-l),_) 1--(>::t. 3 D3) :::-·::::.1/1-. }/1/f2,Q /, I ·• C, 3)(D2.) (,1{(1) -= J, 7 ~ 2,7 ~ ,R&r, , "3 Dz- Signature ~ 7D -I ,) 2-- Reviewed By ____ _ :"-. ' . "·('\ " -total ADT* = "\'\ 336895 2% heavy vehicles, distribution not available "'-. ~ percent of traffic truck composition Al.IT eqpivalency factor EAL £18-kjp, daily} 0.98 passenger cars 330157 0.0006 198.()9 0.0028 busses 943.306 11.52 10866.89 0.0114 pickups (8,000# gross) 3840.6 0.0203 77.96 0.0028 2 axle, 6 tire (12,000# gross) 943.306 0.1203 113.48 0.0009 Concrete trucks 303.206 4 1212.82 0.0011 Dump trucks 370.585 1.89 700.40 0.0002 10-wheel trucks (46,000# gross) 67.379 2.12 142.84 0.0002 10-wheel trucks (80,000# gross) 67.379 2.45 165.08 0.0002 5-axle, dual trailer (82,000# gross) 67.379 4.12 2TLfifJ. 1.00 TOTAL EAL Ill-kip 13755.17 Note: Traffic breakdown per "Pavement Thickness Design Manual", October 18, 1990, by City of Auburn, Department of Public Works: Rural/Local Residential Roads & Residential Collector Arterial Roads, p.5. *Projected Growth Rate per year (i) for design life 20 2.57% Projected Growth: (TOTAL EAL)[(l+i)"-1/i)=G 353858 0.35 EAL for design in millions * Traffic data provided by Curtis Chin, P .E. of Transportation Engineering Northwest, I.LC CIVlL ENGINEERING REFERENCE MANUAL Appendix B: Revised Soil Support Correlations '(.1 r; ,I,, ,t, { -10 - '-9 ~ '-lJ L.. ~1 . '-;;; .E ./2 '-6--~ m '- , ] a: '-5 ~ -4 L LJ .... L.. 2 L.. L.. 1 -90 -90 L -BO "-80 C. ---,., - -60 -60 -- 50 '-50 cc. 0 ~ 1,, C ~ -40 .. :... 40 ~ mL , L... g! a: -30 L. 30 L.. L.. L 20 20 L L... '--10 L •~ ,_ .... 0 .... 0 t: 100 c.. 90 t: 80 '-70 L.. '-60 L.. 50 r-( (...l-,r 40 µ,,.{rd L.. -- L.. '-20 ~ 10 '-9 a: L.. CD L..8 u L.. 1-7 L.. L.. 0 L.. '-5 X L.. m 'tJ 1-4 .5: a. , e 1-3 '" L.. L_2 ,_ L...1 L.. L.. • E, a: ::. ~ , Lo g, ~ a: 0 L.. • , 0 L ,, 0 LS ::. L.. L L.. 10 L L.. L 15 L 20 L.. 40,000 30,000 20,000 10,000 9000 8000 7000 6000 5000 4000 3000 2000 I'- ~ \.-, ' ;e ~ a: !:' :.; a 'i a: Rll«lGRM'II SOUIES, 109iot 4.: ~:.s ] log1't'18 = 1-g*S0+ 9.36*109i 0 (SNt-l) -0.20 + -------'- 1094 + 2,32*109io"it -8.07 ~ 0.40 + 5 19 (Slit!) " \. jt 50· = -. = . -~ -'C· -~ !! ·,·~1~ ~ - 5.0 .s-~ ~ a.·2 =.: ,-40 ~~j ~jt,o -~ z ui I~ 0,q "C =:, O-v o ~ :: .5-t-O a: °g ._ -(? CD::::i:: 5 -~o ~ci--e• ~~ .... J~';~ ffi1ii~ ~~ c£ "-"I .OS-~ .; &ample: w,o : 5 • 10 .X-R, 95% • 0, 35 .. A, l(,y-,.-.. 0 ,tC:: ~~ " Design Serviceability Lo&$, 6PS1 /,. ,1' r ~ 7 /,;, w , , , , r7. ,,, ,,., I, ~ Lr/ I~ V' I.~ ~ • ' • • • 9 8 7 6 S • •2. 'l 2 Desi9n Slructural Number, SN / ,, --Xe so, 0.35 * MR , 5000 psi '-I: APSI , 1.9 i0 1 OCO (' s, (,:.Jo.. .L,,_;( a.,,,,J 5.f..,..ve,LP.,,.,,Ji r_,J/ SubhA.Sc) 5tt"v:./ct5L I, 5 Solution, SN ' 5.0 ,;. , 7 Figure 3.1. Design Chart for Flexible Pavements Based on Using Mean Values for Each Input ~ 1z., n'\ Co V( ~-er-s,1-w-J."~ill p__y sv, ,e ;, v' J:.,....,,_o '\ ---------~--- =::: ~ 4 .,., ;ii ~ ~ f ;. ~ . - 1'. ~~. ......... ~. 0-. ' ' ~ ~ "' ~ :;; !:! D "' IUICGRAFB SCID1IIS: w lOJiot 4.: ~:.s] 103i0 18 = Zi!"S0 + 9.36*103i0 (S11H) -0.20 + ------ 1094 0.40 + (Sllt-1)5.19 + 2.)2*1<>9i.o"a -8.07 l il Design Serviceability Loss, ~ -40 ---" ~ .......... ___.-.::; r,j ,,/ 2 :10 ~ = " I/ V, ~~ ' .!!! ~ '/ 1//, ~ ~ ~ -· , , (A ,vv, «/ / ~ ,/ //J ',I ~ .,,, ll'.: I I • I w,o: 5 .110'-=--,3S.,JO(:, 9 8 7 & S 4 C>PSI I ' • 24s• R : 95 °lo ":. 8 S /{l Design Structural Number, SN so: 0.35 -.: 0, ::; MR ' 5000 psi : Zo)'O O 0,,.a 1-el /,,or,rt'f.,._,, 6PS1 : 1.9 -:. , , < Solution, SN , 5.0 -.2.. "f 5 Figure 3.1. Deslgn Chart for Flexible Pavements Based on Using Mean Values for Each Inpnt . ~ :::, ~ f "" ;p i • ,a ~ i, n i, ~ ~ "= ,-'.: " "" ~SOlllES: 109iot 4 .: ~.s j 1094 w log10 18 = Za*So+ 9.J6*109i.o<S11+lJ -o.20 + ..... c,,O ... .Ji! -r.. .,, 0 ':!!. ~~ ~ ~~ a:: 0~ ~ :;; .!! -; a: 00 80 70 •• 50 .g '-· ~ L -.4 ~-. " l. .... __ _ 50 10 jl c! ,!? D " -> '3 • ,E°: a.~ :;a " ti,~ -0. o.: ;; .. .~.3 t ;----'· !~ ne l&J~ .; O .40 + (SIi+ 1) 5 .19 Example: =~ ell -;; 'C ::;; Jj a; -g .a 0 , a: 1l ~~ 0 C ~-" ffi J + 2.32"1°'3J.o"'a -8.07 Design Serviceability loss, 6PS1 di I / I ' I ,/" I/ V ' ~ , , /, / ,, µ,,' /1 0,; ,.I ~ ~ l~, ... ~ ' ' I r ' ' 9 8 7 & S • • z w10 :; s JI 106: • ;,s,,, 10 6 R ::. 95 °/0 ;; ?,""i;' ;'., s. = 0.35 , 0, ,;- Design Structurof Number, SN MR =-sooo psi ., :26, oc/)p~1 {(!/c11.,: /,,_,.' Srv• ;(r..c.:-• .. -=,) 6PS1 • 1.9 ' , , < Solution: SN = 5.0 Figure 3.1. Design Chart for Flexible Pavements Based on Using Mean Values for Each Input , ./ ~ t, ~-.,., ;p ~ ~ !:' 2 2 a "ii ii',-·: :.-:()("1,:.1 i ~·: J ·,' l'IR\'ES TEST l l•IG El·IG lflEERS MAYES TESTING ENGINEERS, INC. r, c\T!'.· ,-T. IHIT: ·z {$/1 §61 tMA#d iii;:1 ·&11ftlL3M 1t¥HSl&ilJ 8/1 81201H Associakd Earth Sciences, Inc. KE01.iOSG ·----- 1•1:i"JJH.T !i _Q102.!!.._ _________ _ L t\B !i 8740 REPORT STATUS: Original 0 Amended 0 SAMPLE DESCRIPTION: ~25 745 17.37 Ew1mtt Off/oo 91M34tt1 Street SW Sulle A·1 · Everett, WA 98204 ph 426,74~.9360 lax 426.745.1737 Tsooms Offlce 10029 S. Taooma Way Suile E:~2 Tacoma, WA 984!:1..l ph 2fl~.5M.3720 fax 253.594.3707 Portland OHlt:s 7911 NE 23rQ Drive Suite 190 Portland, OR 97211 ph 500.281.7515 lax 503.281.7579 Brown Sil1 w/grnve) (Native Shamro::::ok:;,) ____________ _ ---·--·-----· ----------------------------------- TEST RESULTS: California Bearing Ratio ( ASTM DI 883 ) Sample .. ~. 8740 _g_esc1iprion -----~--------B_ro_wn __ S_il_t_w_/gra~_v_el ____________ _ ~la::0.:1""" Dry Density (lb/cu.ft.) 129.3 (ip1i11111m Moi:-:ture-Co_n_te_n_t_o/._, _______________ 8_._s ________________ _ .. L:,ghr orSur,har~~-1--'b-'-s----------------'l;,;Oc..O=---------------- ,:-;, ~well al ~fox Dry ::D..:e;:n:;,i::,ty'---------------'0-'-, l:..:o/,..:'--------------- ·~-1 I( =1_1!~f:u:in1um Dry Uensity .1" 82.0 . --------------·------------·-------------------- ----------·-··---· ····· ------------------------------ ·------------------------------------- Reviewed By:,a.._.,~Q,;:~~Z,.L-=::=-- 11d•·nmti1m rn 1hi~ n:p,:,r1 llpplic:, only to the 111:\uo.\ samples tes!cd ;md shall nol be reproduced cx~opt in ~U, Inc. CBR Rciiul.15 'i:.740/8/1 S/2004 '~' ' b (L ['-r·, e--,n 7 ['- tn [\) "' 82 w ~ CJ ai ~ >-u, w >- rn ~ .-._, " $ California Bearing Ratio (ASTM D1883) Laboratory #8740 90 I I I I +· ---~---1 i _ __;__ __ 1 I =:/= . 80 I 1··-··----J I . '. ! __!...._. --1--•· :---1-1-~L -·-' ~-1 I I I l ---+------::~.::-··--:-·, . ·--_i_J . r ' :::'= .: ·-: . ,---; _1:::-1--i I . :-'-~ ---· I + I ·-~ / -+ I I I ! f i I 1--j--j--l-l V ·t ,-+-1-.J-J 70 V 60~ ,,.. --+--+-t-t-+-+-+-+--+-l·---!___:_·---1·-+-+-+---+--j-1 , , , , , , 1 . , , :;v1 , , 1 , , 1 ±J I I 1 J. ./ "' ~ 1 1 1 1 1 1 1 1 1 1 ; 1 1 1 1 1 l-l--+-J-t-+--1-+++-1 ; I ! I )1 I : I I . I I I ! I I I I I I m > 50 I I I I I I I I : I I I I 1-1--, f-+-+---+-' ·H--1 I I I I I J,4 ! I I I I I ! I ' I I I I I ; I I Ir Ill u Fi--+ . I : 11· 111 . 1111 i 11 JJtt~~=t:B:JJlft ____ tJ I ~f~=J-H . I i 111 •· 111 40 H--'-~--+-H ---;--r=ti~~ i I I 30~ j ! ; j · 11 lf!faJJmtli•I I I -'++1 I I I ---rr o le., n _L_r+-c:-:::t::tt=1 -' 18-J.b u . .fl ~-. '--f-;-! I . , .... ·I·: i 1· , .. I :. :"·' .,..~ ,T: 20 ~----I I ~-4-·--------1---1 ----· --. --, -·-_ -· _ . , ' '-±:g; lJ=:;__4£.r-~-::-11~:-ff .r-:r ~ 1_, t -· i--1-~ -t_-::t-j-_,_ i · l~,--1 j_L93 ,O. 1-=f:-:-i ; ! i=R=l ·· 1 :--::=-:::-_--i · i -~: ~ --f1-1 , 1 i r=r: 1 +1='. · -, J 1 • E a<-' ,v ~20 ~ ,., -,,. to<:..: ·123 Dry Density {lb/cu.ft.) '";' ,.4 125 ~20 i27 128 \/;';v,~:s :·est ·10 Cn..;JJi';E!F .I _;,; -J :::--;-1'.rfj:,:) j :: : ! ',' MAYES TES TI HG EHG I elEERS LJ25 7,15 1737 Moisture Density Relationship Test Assut::l.tkd Earth Sciences Inc. Date 8/18/2004 l~·ii1~m P!1;je,:1 r·1 1·;1 ~krhcict l)uall!:LC_c._·o'-o..,tr7o.c.l-,-,-,..,.~-=c-c ASTM _I> 155i_ Metho<l CJ ASTM C: 127 / 04718 (if needed) Project Number ·Lab Number Q4029 (KE0!50S G)_ 8740 \' ,-1 f·'-·,:p,m1hclf\ [~ 1 Hand Tamper LJ !·11·:. Prcp;iralinn C\] Mechanical ITJ r!atr: Rt~c,::iv~d 8i'll:!004 ,-,-.--,-- ;._-,i!f(•::-of:)rmiph:: i.,lttlivt. Shamrock 8.8 129.3 f ·, •'.::<cr!µ1fr1n of Sarr 11-1 le; J:~ ;1~~;ilt with_,gr=av'-e_I _____ _ Sieve Size Percent Retained 3/4 18 b·1...-, \',)id line pl011r:d ot ~)pG 2.75 3/8 32 , ~;:~~:· T:.>~e,~-1~~~~=~u::·~~-~~-°_~'~:_:c:t~:~~-:. ~-~12§9~-~o::!~==-----=======,:;::;::;::;;;:;;:;#4:=:=::;::::;:::;:;;:::~:;:4:4===i 0.0 2,0 4.0 \ "'Vo'<H'llt91'1:--·· = ··-01• ~ ! 1-- I .· I -, I I . II . -, 6.0 8,0 10.0 12.0 Water Contenl, 'I, of dry Weight Reviewed By: l111',,n11.!tio11 in thi~ repon ;11lp!ies or.ly lo th~ actual samples tested and shall not be reproduced except i Engineers, lnc. . c. -,~ 14.0 '' ' ·-I ·-..,...,_!.. -11 ' • I 16.0 . : ! .. f-r : I··-.....+. -;.., ·l· . -(· - _i: -: , .. 18.0 : MAYES TESTING ENGINEER$ 'We Maka a Difference" d :;! r u ,:SJ ·..:J s, 0 ·. ;al;,,,, C Si--·.'f''T'''" ·., \,.-::·c:· ________ =r ___ · ·--· 11;·:Ti-~, ~:·:,\:::,,: r•::_,_~_,._._,,_,_,_,_~--··_•·_• ------ . ' ,, m " 1,4 . " !>;· .:, " ~ ., ·:tr,~ . JJ~f ~r ....•. ~. · L 1~ li Jtt .J~I)·~ "F-fil: . =~~ :-=:~ -~J;r-f:_=i¥}t+~ :: -··--:= ==·Ji . ~--------- ----' "'§i ., --· . --t=f:--~-··-·_ ..::___ -· _ .... ·------·- " __:-, l=t= ·-----·----------- ] so~ -·-t---~ _t::j_ ~-, .. _ , ----+- "' I= I= t-t-· t---· ---H-.. ·--+--t----· t----- JO ·++--·-+"· ··- ,. -- " ----t--1-----t--··- • --! S~ev,c Am~lv~i.s . -------------·--' .·· ,, " lt Si:.:'.'(' .::\Lt'- ].:}\!'' ' .-.·.~-___ ,,, ~-;, hssi.ug'* I(){> '}\: 1 S;;·:c ._ 1 /, mm; rt'oi!.~ I £ .J i 2.JO" 9; I 1::-.; t---~~;;: ~~ I i 87 I I .1/4"' 83 1 518'" I so 1/2" I 7S 3/S" 69 1 i 11 1/4" 62 ni •J1 I #4 57 ---; iIB 49 rn <J1 #fO 47 , :: I· #16 42 I a l #10 ·35 ,140 I ,o I I !ill #5,0 I 26 G"J •100 I 18 I I lffi 11200 124 ~ ti,,-::. 10,000 SM "' •• ,., O.Ol (".n,1111 Siu (mm] -Cc111S r>f E1111ineec:1 Uai:flirm Sall C!'11q!Rca1111C1 Classification NnL W.C. IL.L. P.I. Si:.~~-! ,r:~. ;.;,-::,J,,J.4 Matenal: Source: Project: Project#; Date Rec'<l: Rrnct••t:d !iy: Brown sandy silt with Native Shamrock Quality Control 029 (KE 01508 Gl MA YES 7-E.S.TiNG ENGJNEEA.S '"9'•( w,.___1,,. ~ ~~ir{,,1-t .... -:<c vcl "' rv Vl ;;' 'Jl ~ ...] l,l -J 'D C:J -~ :, ·7-· :'0U,:1 l.~: l'.· MAYES TEST 11,1G E"IG I HEERS .:125 745 1737 P.@2/f::I'"! MA YES TESTING ENGINEERS, INC. b JiATE 8118/2004 ====------CI .ll·J,lf: As:w1:ialt0:tl Earth Sciences, Inc. l'iiO'FCT: KEOJ 5<J8C; ---------'------- Fl!O IJ'i T # Q402fi : i'.l~. if 3741 -------··------- ± REPORT STATUS: · Original 0 Amended D SAMPLE DESCRIPTION: Gray Sand w/gravel (Shamrock Fill) Everett OH/cs 917•134U, Street sv.1 Suile A.-1 Everett, WA 96204 ph 425.742.9360 fax 42S.745.1737 Tticoma Office 10029 S. Tacoma Wny Suite E-2 Tacoma, WA 98499 ph 253,5&4.3720 fa.I( 253.564.3707 POl't10r1d OffiCtJ 7911 NE 33rd Drive Suite 190 Por11.anc1, OR 87211 ph 903.281.7515 fa.I( 503281.7579 . -------·---·-·--------------------------- TEST RESULTS: California Bearing Ratio ( AS1M D1883 ) Sample# 8727 Description ______________ __::G::.ra:.:ya.::S;:an::.d:....::v,c:,/gre:.::a::.v::.el:_ __________ _ Mc.ximum Dty Density_:,_,(c:lb::./.:.cu:.:·.:.:ftCJ..) __________ ..:1::.36::.·..:4 _____________ _ .. Op1ir11un1 Moistrne Gi::.n::te:.:n::t...:%.:, _____________ ....:.7::.9 ____________ _ _ ----~\'e.ight of Surcharg'--e_l_b_s _______________ I_O_.O _______________ _ __ __:·, ~well ~t Ma., Dry Density OJ% t HR,:':? Maxi1num Dry riensity .1" r01:n~::;r a~ \1~£1J~1~~:~~:~.J . 64.0 .. . -------------------·------------------------ ···-----------···· ------------------------- -------------------.. ·------ ---------------·-·····------------------------------- Reviewed By: _r...::::....i:::::::;,.;.:;,.,::..::a:.._ __ h,rl'.m·,J110r1 in this r~p,:,11 :ippli<:.~ only 10 tl11: actual samples \csti:d :md sh.\ll not be reprodu~d except~ Inc. r.·nR R.r:snl!" 1n411:i/) H/2004 C· :•~J C, "- ['-,,, ['- ~ ,-, 'Sf ['- "' 1-·J 'Sf IQ w ';!! ~ ~ >- Ul w ,_ U1 ~ :a: f California Bearing Ratio (ASTM D1883} Soaked Sample. Laboratory #8741 70 I I 65 --i-+~-l--~--1-1 1--+-+-+-+ I- I l --~ -- 1 I i I 1 IF I I I I i l=i·~-=1=1 I 1-=1=t·r:±-=H=t=·1 I I · I l----'--1--------1 i ,,,fl Ii ~cL· f I I I I 1-1 1 60 I .. I "' I I I I~ I i I l=ttT I ~:H--~=1 • I i I I I : I I I I i-ttr 1-1 ~ I I ::, .; > 55 ~H-f ii: m 0 1--1--1--1 I 1-t I i I I I I I f--!-+-f--/-1 bl 4 I I --,-,....-i-. -t-t--j--j--t-t--t-.-t--i V, ' 50 1-11-111 !l--1--11f1MUffltfJ=t1f--=ffll i t1-fF1111-1 ! V -= i 117_ 1 45 }-r ' -. -f---1-I -----I I I ' ! ' I I ------· • "---I · i "i : t ---+-!-~ -! · ----+---L--~--: I .L ... _____ !.. .J. --__ L __ : -. I .r_:_!_ . I ! _ .. _ _l __ . ! t - 'H-f-1 -, , , i ! I · i I i I I ! I I 4o -.i 1 --·.. ··rr··1 : _ .. ------· 1 -·-t-t 1 1 r-· : 1_ 128 129 1,:1:J 1 ::i ., ":32 133 134 1 :3.5 1 '" -- Dry Density {lb/cu.ft.) ' ' -; r 137 ~.1::,:z~ ; e.s::, · ~ =::::::;,::=: ~'-;;:- :::'r--~ _, Q! ~1 r-n , .. ~ ,, " ('- "' CJ " . ~ '"° ,. f -- i •• 10 "' i so (/) °' tl! L ~ ... ,. u .. .. ~ " --+---t---t-\- 5ie\'t Am1.ly~b Siu apt:mns in mdlc~ Nlmlber ofM~b p,::r Inch. US S~ard 1'4 "4 " " ,. .. " ·~ ,., , ____ _ --1----t·-t-----+--+-- --!-1---i--- ==l=:=-=t=-·-·- --+--~--+ r-··--r· I- E'S -- g if; :?O I---. t-H·--+--~----- ~ 1-,n w 1- 10 f- • ''"' ,_ 1---l--+------t--+. ~ l a -------------- ,: 10 I------+----" --·-··-!-·-+---+---,-__ , ·-+--·+ .,-. 1-H·--·-······-~- --1--t---+--···--i- 0.1 G.-ain.sizc, tmml-r.:orp5 dl?II.Pll,N'~ u:nm1r111So11C'l:uJinc:t10fl >ampli: NumberlDepth (ft)! Classification J.1"~1._w.c. !LL J -!r.L 374-1 SVJ-?M ! I I : ' --LI i - : -. '------------ .-"-. ,:"., ,:)1eve Analysis Si.eve Size I Speos. %, Passm~ . mio max. 2.56" 100 2.00· 99 1.50" 96 1 1/4 94 --l 90 ---3/4" 85 518" 82 112" 76 318" 67 1/4" 56 114 so 118 42 #10 )9 #16 33 --ii)() 23 #40 18 #50 15 #100 10 #200 6.7 --- --- ---- ----H11. :101 000 0.01 Material: Gray sand and r;!nlVel Source: Shamrock Fill jf!:_ojc,c:: Quality Control ______ _jPro,L:~.·f: ___ ~.--~---- !Dm~ R-:--:-'d: _ .,./Rl91p4 _/_.,<,{·-:-:-~ 1 ) } ' -' / i:/ {:J_ / b,c,v,c --.,--l /~ ..-:&?;:~- .. -··· --~·' / !,];:.. ":"..:":3: :--cs.-:N"G ~UGJHEiEh!i .,_""1<1 ff'1tk.f!-_,, Oi~m"~ 11RYES TEST I l•IG Ei'IG I flEERS i\25 ?'-15 17.37 Moisture Density Relationship Test F ;(,jt,·r Associ11ted Earth Sciences Inc. ()ualir>' Control Date 8/18/2004 t , ... ,! },fr;tltod ASTM D 1557 Method C/ ASTM C 1271 D471S (if needed) Project Number Lab Number Q4029 (KE 01508G) 874[ 1 ):,,:n)'~·nid liu~ pt;i·1;J··,;c·s1;oi 1s i \'l;'.J :,:_, Dr•n,;.lty Voc.:irrect,::d 136.3 ,...,...::>PT..,.,. .,. ... ..:.=-,=~=-=-·== :-2 ·-:•,!, !l j ,ij ·., il:it1 4,0 I I . -1--: ' i ... ' L ... _c .1 •.• .,. I . 1-• . l-1-I ·+ I·· L-r1 . . --1- 1·1 "I ,. 6.0 6.0 Water Content,% of dry Weight 7.9 136.4 Sieve Size 3/4 15 3/8 34 #4 51 ' -1--,· ' . ... L I· ,. ' . I . ~ , ... ' I:. : ... , . . I ' ·-•• -1- . ' I; ·--:. -1--•• - • L • + 10.0 12.0 14.0 I Reviewed By: .!::~~~~~~.i.....,._,_ .. lnf,n11111\r:m iu \Iii~ rO?p,m .111p\1es only 10 !he o.clunl so.mple!i lesli::d 11ml shall not be: reproduced except i Enginetll's, Inc. MAYES TESTING E!NGINE.E.RS "We Mako a D/fferanoQ" East Renton/Rosemonte -Early Start Technical Information Report 7 OTHER PERMITS o FPA o NPDES Job #01-047 June 25, 2008 Page7-1 East Renton/Rosemonte -Early Start Technical Information Report 8 TESC ANALYSIS, DESIGN AND CONSTRUCTION STORMWATER POLUTION PREVENTION PLAN Temporary erosion and sediment control (TESC) measures such as Clearing Limits, Cover Measures, Perimeter Protection, Traffic Area Stabilization, Sediment Retention, Surface Water Controls, and Dust Control will be implemented according to Best Management Practices (BMPs). The clearing limits will be flagged prior to beginning any construction activities. The downhill perimeters of clearing will be protected with double filter fabric fencing, and other perimeter protection methods as required. Cleared areas will be stabilized with various cover measures as required (e.g. temporary/permanent seeding and mulching,). Stabilized construction entrance will be provided at the construction accesses to the site. Interceptor swales will be installed to collect and route runoff from the disturbed areas to a sediment pond or to sediment basins that recharge the wetlands. The sediment basins will act like and are sized according to sediment traps. Dust control measures will be implemented if there is a need (i.e., if there is a particularly dry period during construction). Peak runoff rates used to size sediment control facilities were determined using the KCRTS program. Parameters used for the program were a Scale Factor of 1.0 Seatac, till soils, and hourly time steps. TESC Measures were designed per Section D.4.5 -Sediment Retention of the 1998 KCSWDM. 8. 1 Sediment Pond The sediment pond has been sized for the entire project minus the wetland recharge, land cover is assumed cleared and graded. The required surface area of the sediment pond was computed using the I 0-year developed peak flow rate considering cleared conditions. A summary of the erosion control calculations for the sediment pond is provided below. Site Areas Job #01-047 June 25, 2008 Till Grass Impervious (244 1h Right of way, gravel drive) Minus the area to Wetland Recharge Total area 14.52 acres 1.14 acres -4.16 acres 11.50 acres Page 8-1 East Renton/Rosemonte -Early Start Technical Information Report KCRTS Peak Flow Flow Frequency Analysis Time Series File:pond.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--------Flow Frequency Analysis------- Flow Rate Rank Time of Peak (CFS) 1. 48 0.756 1. 88 0.309 0. 816 1. 52 1. 36 3.50 Computed Peaks 4 7 2 8 6 3 5 1 Surface Area (SA) 2/09/01 1/05/02 2/27/03 8/26/04 1/05/05 1/18/06 11/24/06 1/09/08 2:00 16:00 7:00 2:00 8:00 16:00 3:00 6:00 -Peaks (CFS) 3.50 1. 88 1. 52 1. 48 1. 36 0.816 0.756 0.309 2. 96 Rank Return Prob Period 1 100.00 0.990 2 25.00 0. 960 3 10.00 0.900 4 5.00 0.800 5 3.00 0. 667 6 2.00 0.500 7 1. 30 0.231 8 1.10 o. 091 50.00 0. 980 The peak flow used to size the surface area of the sediment pond was .. conservatively chosen to be that of the IO-year storm event instead of the 2-year storm event. Required Pond Surface Area = 2 x (Q10/0.00096) = 2 X (1.52/0.00096) = 3,167 sf The Required Sediment Pond Surface Area is 3,167 sf. The Provided Sediment Pond Surface Area is 15,416 sf. It is intended that the detention/water quality pond be constructed with the Early Start Plans and utilized for temporary erosion control. Dewatering Orifice A, (2h)Yi 0.6(3600)(T)g 112 A0 = orifice area (sf) A, = required surface area= 2,521 sf h =headwater above orifice (3.5 ft is minimum) T = 24 hours; dewatering time g = 32.2 ft/sec 2; acceleration of gravity 3,167(2 * 3.5)Yi = 0.028 sf D = 24 x (AJrt) 112 0.6(3600)(24)(32.2) I 12 D = required diameter (in) D = 24 x (0.028/3.14)112 = 2.266:::: 21/4" Job #01-047 June 25, 2008 Page 8-2 East Renton/Rosemonte -Early Start Technical Information Report Overflow Riser From the Overflow Riser calculations, the height of water over the riser is 0.39 feet. An 18 inch riser is provided with 0.50 feet of head to pass the 100-year, 24 hour storm event of3.50 cfs. Transition '' > '' T •I ,., 4.00 ; ' H ,. '-~ ·., ,,;, I/ 3.50 ,D--' ,, ~ V 3.00 ' ., ,,, I/ " ·I e' 2.50 o, fice ff ,, ' ff . ' f 2.00 :! 1.50 V Input Output "' Id Wei Q (cfs) 3.50 3.50 1.00 . ,,(/) D (In) 18 18.00 0.50 H (ft) 0.39 " X 0.00 Flow: Weir Flow 0 10 20 30 40 50 60 70 80 90 100 110 120 130 Diameter (in) . . 8.2 Sediment Basins The sediment basins have been sized for the area draining to them with cleared and graded conditions. The required surface area for a sediment trap has been used for sizing the basins and was computed using the I 0-year developed peak flow rate considering cleared conditions. A summary of the erosion control calculations for the sediment pond is provided below. Basin B Till Grass Impervious KCRTS Peak Flow Flow Frequency Analysis Time Series File:trapb.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- Flow Rate Rank Time of Peak (CFS) 0.078 0.042 0.098 0.022 0.044 4 7 2 8 6 0.080 3 0.073 5 0.181 1 Computed Peaks Job #01-047 June 25, 2008 2/09/01 1/05/02 2/27/03 8/26/04 1/05/05 1/18/06 11/24/06 1/09/08 2:00 16:00 7:00 2:00 8:00 16:00 3:00 6:00 0.79 acres 0.03 acres -----Flow Frequency Analysis------- --Peaks Rank Return Prob (CFS) Period 0.181 1 100.00 0.098 2 25.00 0.080 3 10.00 0.078 4 5.00 0.073 5 3.00 0.044 0.042 0.022 0.154 6 7 8 2.00 1.30 1.10 50.00 0.990 0. 960 0.900 0.800 0. 667 0.500 0.231 0.091 0. 980 Page 8-3 East Renton/Rosemonte -Early Start Technical Information Report Surface Area (SA) The peak flow used to size the surface area of the sediment pond was conservatively chosen to be that of the JO-year storm event instead of the 2-year storm event. Required Pond Surface Area = 2 x (Q1w'0.00096) = 2 X (0.080/0.00096) = 167 sf The Required Sediment Trap Surface Area is 167 sf. Basin C Till Grass KCRTS Peak Flow Flow Frequency Analysis Time Series File:trapc.tsf Project Location:Sea-Tac 0.44 acres ---Annual Peak Flow Rates--------Flow Frequency Analysis------- Flow Rate Rank Time of Peak --Peaks Rank Return Prob (CFS) (CFS) Period 0.039 4 2/09/01 2:00 0.093 1 100.00 0.990 0.020 7 1/05/02 16:00 0.050 2 25.00 0.960 0.050 2 2/27/03 7:00 0.040 3 10.00 0.900 0.008 8 3/24/04 19:00 0.039 4 5.00 0.800 0.021 6 1/05/05 8:00 0.036 5 3.00 0. 667 0.040 3 1/18/06 16:00 0.021 6 2.00 0.500 0.036 5 11/24/06 3:00 0.020 7 1. 30 0.231 0.093 1 1/09/08 6:00 0.008 8 1.10 0.091 Computed Peaks 0.079 50.00 0. 980 Surface Area (SA) The peak flow used to size the surface area of the sediment pond was conservatively chosen to be that of the JO-year storm event instead of the 2-year storm event. Required Pond Surface Area = 2 x (Qiw'0.00096) Job #01-047 June 25, 2008 = 2 X (0.040/0.00096) =83 sf The Required Sediment Trap Surface Area is 83 sf. Page 8-4 East Renton/Rosemonte -Early Start Technical Information Report Basin D Till Grass KCRTS Peak Flow Flow Frequency Analysis Time Series File:trapd.tsf Project Location:Sea-Tac 1.91 acres ---Annual Peak Flow Rates--------Flow Frequency Analysis------- Flow Rate Rank Time of Peak --Peaks Rank Return Prob (CFS) 0.171 4 2/09/01 0.087 7 1/05/02 0. 217 2 2/27/03 0.036 8 8/26/04 0.094 6 1/05/05 0.175 3 1/18/06 0.157 5 11/24/06 0. 404 1 1/09/08 Computed Peaks Surface Area (SA} 2:00 16:00 7:00 2:00 8:00 16:00 3:00 6:00 (CFS) Period 0.404 1 100.00 0.217 2 25.00 0.175 3 10.00 0.171 4 5.00 0.157 5 3.00 0.094 6 2.00 0.087 7 1.30 0.036 8 1.10 0.342 50.00 0.990 0.960 0.900 0.800 0.667 0.500 0.231 0.091 0.980 The peak flow used to size the surface area of the sediment pond was conservatively chosen to be that of the JO-year storm event instead of the 2-year storm event. Required Pond Surface Area = 2 x (Qio/0.00096) Job #01-047 June 25, 2008 = 2 X (0. J 75/0.00096) = 365 sf The Required Sediment Trap Surface Area is 365 sf. Page 8-5 East Renton/Rosemonte -Early Start Technical Information Report 9 BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT 9.1 Bond Quantities A Site Improvement Bond Quantity Worksheet will be provided at the end of the engineering review process. 9.2 Facility Summaries Refer to the final TIR for the facility summary worksheet and pond plans. 9.3 Declaration of Covenant Not applicable. Job #01-047 June 25, 2008 Page 9-1 East Renton/Rosemonte -Early Start Technical Information Report 10 OPERATIONS AND MAINTENANCE The temporary sediment pond will be a privately maintained system. Once the permanent pond is constructed and in use it will be a publically maintained system. Job #01-047 June 25, 2008 Page 10-1 ti King County Road Services Division Materials Laboratory Department of Transportation RSD-TR-0100 155 Monroe Avenue Northeast, Building D Renton, WA 98056-4199 www .metrokc.gov/roads October 6, 2008 TO: Ted Cooper, P.E., Engineer 11, Department of Development and Environmental Services, Site Engineering and Planning Section VIA:. Alan D. Corwin, P.E., Materials Engineer, Materials Laboratory, Project Support Services Group FM: Douglas Walters, P.E., Engineer, Materials Laboratory, Project Support Services Group RE: East Renton/Rosemont Pavement Analysis: L07SR054 As requested, we have reviewed the designed arterial pavement section for 1481h Avenue SE associated with the East Renton/Rosemont Development. The design pavement sec- tion was submitted by Associated Earth Sciences, Inc. (AESI) while the plans were com- pleted by Triad Associates. Based on our review of the report and plans, we understand the following pavement sections are recommended. o 4.0 inches minimum compacted depth Class B Asphalt Concrete o 1.5 inches minimum compacted depth CSTC o 5.0 inches minimum compacted depth CSBC o 22.5 inches minimum of existing structural fill or equivalent or A TB Alternative o 2.5 inches minimum compacted depth Class B Asphalt Concrete o 3.5 inches minimum compacted depth Asphalt Treated Base o 4.0 inches minimum compacted depth CSBC o 22.5 inches minimum of existing structural fill or equivalent We concur the first design pavement section is adequate and would recommend its ap- proval. However, the ATB alternative section does not meet the minimum ACP depth of 3 inches required for a Collector Arterial. Therefore, we would not recommend approval of the ATB alternative section. We trust this information meets your current request. Please call me at 296-7708 if you have any questions. August 6, 2008 Mr. Ted Cooper Engineer II King County ODES M.S. OAK-DE-0100 RE: East Renton and Rosemonte Plats King County File Nos. L02P0005, L03P0018 Subject: Response to Early Start Comments dated 7/30/08 Dear Ted, 12112115thAvenueNE Kirkland. WA 98034·6929 425.821.8448 425821.3481 fax 800.488.0756 toll free www.triadassoc com Triad Project No. 01-04 7 Below are Triad's responses to your comments on the Early Start Plans dated 7/30/08. I. No Tree Retention and/or Soils Amendment Plans are required, per Bruce Engell's 6- 19-2008 e-mail. 2. Submit 3-sets of each of the following to insert into the 3-TIR's: a. Submit all specifications and calculations for the pond, its overflows and orifices. Since flow control is required now and the permanent pond is being built now, it makes more sense to install the permanent FROP-T and orifices in CB 45 now. The pond & orifice calculations look OK for the permanent pond. Also update the plans. Triad Response: The TIR and plans have been updated respectively to include the calclations and permanent storm drainage structures associated with the permanent pond. b. As designed, a minimum 21 "-diameter riser (with no more than 0.5'-head) is required because this riser must be designed to convey the I 00-year flows before the pond's emergency overflow weir starts to function. See the required overflow sequence in Sections A-A & C-C. Also update the plans. Triad Response: In lieu of increasing the riser diameter from 18 inches to 21 inches, we have raised the emergency spillway by 0.1 feet which allows the pond's overflow riser to be fully engaged before the emergency spillway starts to function. We've also increased the spillway length to provide 1.0' Mr. Ted Cooper 2 April 15, 2008 of freeboard between the emergency water surface elevation and the top of the berm. c. In the control structure, minimum 3.8' (SAY 4.0'?) -wide jailhouse weir is needed.The proposed 3.5'-width minus 11-#5 bars doesn't provide your minimum 3 .2' -calculated width. Also update the plans. Triad Response: The length ofthejailhouse weir has been revised to 4' to accommodate the with of the rebar. d. Submit bond quantity worksheets, an RID facilities summary worksheet with the sketch. Triad Response: A bond quantity worksheet and facility summary worksheet has been included with the Early Start TIR. 3. Specify the name & phone number of the ESC Supervisor (per requirements for "highly sensitive sites). Triad Response: Verne Wolley has been listed as the ESC Supervisor on sheets 4 and 5. 4. For all pipe outfalls, the "TEMPORARY SUMP" and the pond/sediment trap emergency overflow spillways add rip rap pad dimensions and material specifications per this table and figure. Triad Response: The dimensions of the rock lined outfall protection for the sediment basins have been sized per Table 4.2.2A and Figure 4.2.28. 5. Resolve the following conflicting pipe sizes for the northernmost sediment trap (6" pipe that has a 12" pipe invert). Triad Response: This conflict has been resolved. 6. Modify the note stating, "TEST PIT (TYP)" so it says "TEST PIT REFERENCED IN GEO. REPORT (TYP)" because it is ambiguous to the LUIS reviewer (and possibly others). Triad Response: This note has been revised accordingly. 7. Correct the contour lines at the inlets and outlets of all culverts. Check ALL proposed pipes and make the changes needed to ensure all of them have I '-minimum pipe cover. Triad Response: A note has been added to ensure that all pipes have a minimum of I' of cover and the contour lines have been adjusted to match the culvert !Es. Mr. Ted Cooper 2 April 15, 2008 8. Label the two buffer lines at the edge of the wetland for clarity. Nick Gillen is responsible for approving these buffer lines and any clearing proposed within them (e.g., adjacent to Lot 76). Triad Response: The buffer lines have been called out as "Sensitive Area Boundary as approved by Nick Gillen July, 2008." 9. For CB 46, use a birdcage on a minimum 54"-diameter TYPE 2 CB with an at grade rip rap blanket surrounding it. Also specify that it is to be field located. A Type IL CB can't be used as proposed (non-standard). Triad Response: CB46 has been revised to a Type 2 -54" catch basin with a birdcage structure at grade with the rip rap blanket around it. 10. Adjacent to the 6'-wide ACP emergency spillway, show and specify the rip rap to be as wide as this weir (i.e., bottom plus side slopes). Also extend the rip rap from this weir downstream and fan it outward to a reasonably level spot (even ifit is slightly in the wetland buffer) so erosion won't occur. Triad Response: The rip rap on the emergency spillway has been extended down the 2: I slope for erosion protection, however the rip rap is not within the wetland buffer because there is no additional area to mitigate for this loss of buffer. 11. In the "STORM DRAIN OUTFALL FROM POND" profile, make the following changes: a. Add a note specifying that backfill over the pipe in the berm must be 95% of Modified Proctor per SWDM. Triad Response: This note has been added to the profile. b. Show the required embankment key per the SWDM and the geotechnical report. Triad Response: A note referencing the detail provided by AES! has been added on the profile. c. Correct the profile location of the control structure (CB 45) so it matches its plan view location. Triad Response: The location ofCB45 in the profile matches it's location in the plan view. 12. Since you propose to install the pond's permanent liner now, we highly recommend the following: Mr. Ted Cooper 2 April 15, 2008 a. Install all permanent pipes and structures that will extend through the pond liner now because it will be difficult and costly to install them later. Triad Response: The plans have been revised to install all of the pond's permanent pipes and drainage structures as part of the Early Start Plans. b. Omit the temporary sediment pond riser proposed inside of the pond and use the permanent riser in the control structure instead (to avoid tearing and later repairing the pond liner). Triad Response: The temporary sediment pond riser has been eliminated from the pond. 13. Resolve the following pond liner issues: (Shown as number 15 in original comments) a. Show the pond liner in all pond cross sections and details of its installation. Clearly show and specify the required l '-overexcavation, the backfill (plus its specifications) over the liner and all required plantings. Triad Response: The pond liner and 12" of backfill on the liner has been added to each of the pond sections. b. In the geotechnical detail, the pond liner is shown above the top elevation of the pond's internal 3: I slopes. This isn't OK. Fill will slide down the pond liner where slopes exceed 3: I. Triad Response: The geotechnical detail has been revised. The pond liner stops at the top of the 3: I slope. 14. Change the construction sequence as follows: (Shown as number 16 in original comments) a. Remove the word "Recommended" from the heading. Triad Response: "Recommended" has been removed from the heading. b. Make the first step say "Schedule a pre-construction conference with the ODES site inspector by calling (206) 295-6642". Triad Response: Number one has been revised to include the text listed above. 15. Correct the bollard locations and spacing per SWDM & KCRS. Locate faces of fixed bollards at edges of access road. Locate 2-removable ones at equal spacing between fixed ones. (Shown as number 17 in original comments) Triad Response: Per a conversation with Ted Cooper, Rick Tomkins and Sheri Murata on Aug 5, 2008 it was agreed that the bollards will not be installed as part of Mr. Ted Cooper 2 April 15, 2008 the Early Start Plans. They have been frozen from the plan set and will be part of the Final Road and Storm plans. 16. Design and completely specify the pond embankments per the "Embankments" section. (Shown as number 18 in original comments) Triad Response: The pond embankment design (as shown in the geological cross section and geotechnical report) complies with the requirements on page 5-20 of the SWDM. 17. Design and completely specify the pond fencing and setbacks per SWDM. (Shown as number 19 in original comments) Triad Response: Per a conversation with Ted Cooper, Rick Tomkins and Sheri Murata on Aug 5, 2008 it was agreed that a 6' high fence would be built to a permanent standard. A WSDOT detail of the Type 3 Chain Link has been included on sheet IO. 18. Embankment fill can't be placed in the ROW of Early Start Permits (see Pond Section A-A). This isn't shown in plan view contours (i.e., a contradiction). Note that roadway embankment concerns must be addressed (but this is part of final plan review/approval). (Shown as number 20 in original comments) Triad Response: No grading within the ROW will be completed as part of the Early Start Plans. The ROW has been labeled in Pond Section A-A, and is outside of the proposed improvements. Sincerely, TRIAD ASSOCIATES Sheri Murata, PE Project Engineer E:\PROJECTS\O I 047\Correspondencc\Jurisdiction\King County\Cover letter TCooper 8M04 I 5.doc ,,, January 23, 2008 Jennifer Reiner Cam West Development Co. 9720 NE I 20th Place, Suite I 00 Kirkland, WA 98034 f&( 1td: K{IO RE: Plats of East Renton (L02P0005) & Rosemonte (L03POOl 8) Sidewalk Extension/Crossing Triad Job No. 01-047 Dear Jennifer: !2112 llSthAvenueNE Kirkland. WA 98034-6929 425.821.8448 425.821.3481 fax 800.488.0756 toll free www.triadassoc.com At your request, we have evaluated the feasibility of constructing an extension north from the Rosemonte frontage on the west side of 148 1h Avenue SE to connect with the existing crosswalk across the north leg of the 1481h Avenue/ 117 1h Street intersection. Condition 13 of the preliminary plat conditions of approval for Rosemonte (L03POO 18) requires that this extension be completed EXCEPT in the event that this proves to be not practical (the East Renton decision contains the same requirement as Condition 12): Condition 13. The applicant shall provide a safe walking access to Apollo Elementary School with urban improvements alonf, the west side of 148tl' Ave NE to the existing crosswalk on the north side of SE 117" St. This improvement includes urban frontage improvements along property frontage of the Plat of East Renton, north of SE I 19th Street, as well as urban improvements along frontage of Rosemonte and urban improvements north to the existing crosswalk on the north side of SE I I 7'h St. In the event it is not practical to construct urban improvements on the west side of 148th Avenue Southeast extending to the existing crosswalk, a new crosswalk may be established south of Southeast I 17th Street and a safe walkway provided on the east side of 148th Avenue Southeast from the new crosswalk to the north side of Southeast I 17th Street. This alternative may use a graded surface on the east side of 148th Ave SE to ensure that school-age pedestrians are provided an acceptable-width walkway surface behind the curbing. The walkway shall be designed to the satisfaction of the school district and DOES. The existing conditions along this route extending north from the NE comer of Rosemonte are marked by four key attributes: (1) a steep drop-off into adjoining private property immediately west of the improved roadway of 148'h Avenue SE, (2) a drainage culvert crossing under the roadway, ending in an open concrete flume that extends west into the adjoining property, (3) a guardrail along the west margin of the existing 1481h A venue roadway, and ( 4) an extensive screening landscape with trees providing a buffer between the adjoining affected property and the arterial road. ~=~~=--...-,~ .... ..,,.-"""""""',~-~ ~~ ..,..,....,.~--.. ,,.,,,,...,, • .,.-.,.,,.,...,,,.....,,,,..,-=.,,,.._:',;"'--.,,.-... -~-. -,-. -, La n d D e v a l a Q m e~l1 t Con s u ! to n ts ~ "" -'"·' ... ' ~ • , , ~ • .;..~•='-"' ' " ' ' \ Page Two Jennifer Reiner Cam West Development, Inc. January 23, 2008 These attributes complicate sidewalk frontage construction -to widen the improved roadway, provide grade transition down from the road to the adjoining private property, and work around the existing culvert and downstream drainage improvement -and this is compounded by the lack of opportunity to perform the work in conjunction with wholesale re-grading and re-development of that entire parcel. We also would anticipate a need for additional costs associated with obtaining (if even possible) needed easer;1enls and installing restorative screening landscaping to replace that which would be lost. We have as-built these existing conditions and have prepared a preliminary design illustrating what this sidewalk extension would entail. This is attached as an exhibit to this letter. Note that in order to keep the improvements within ( or largely within) the right-of-way would require a cantilevered retaining wall to provide the added improvement width needed to remove the existing guardrail, widen the roadway, and accommodate a 5-fl sidewalk. Surface drainage from the added roadway, sidewalk, and retaining structure would have to be brought back to the south -against grade -to the Rosemontc detention pond. While detailed cost estimates would require substantial further design development, we understand that your construction group has estimated the hard construction costs of this improvement to be upwards of$ I 00,000. This, again, does not include likely costs of easements which may or may not ultimately be agreed to regardless of cost. Webster defines "practical" as: (]) Of pertaining to, or manifested in practice or action; --opposed to theoretical, ideal, or speculative (2) Capable of being turned to use or account Encarta offers this about "practical": concerned with actual/acts and real life and experience, not theory; appropriate, sensible, and likely to be effective; plain: functional, and suitable for everyday use The question of whether such a sidewalk extension of some 90 feet costing on the order of $ I 00,000 in hard construction cost alone is, indeed, practical, also requires looking at the alternatives that are available at lower cost and not impacting private property over which the Applicant has no control. In this case, we have a three-legged intersection with two of the legs presently being marked for pedestrian crosswalks. This section of roadway -classified as an arterial -also exhibits an existing stopping sight distance problem sufficiently severe that lowering the crest of the vertical curve creating the problem was imposed as a condition of approval on both the East Renton and Rosemonte plats. This sight distance correction requires re-grading and re-constructing some 623 lineal feet of arterial roadway. An end result of this being that existing stopping sight distance problems will be addressed, and the overall safety characteristics of pedestrian facilities crossing 148 111 Avenue SE in this vicinity greatly improved. II Page Three Jennifer Reiner Cam West Development, Inc. January 23, 2008 Our current engineering plans call for omitting the sidewalk extension to the north. In lieu of this, we propose to bring our frontage sidewalk improvement north to a point some 70 ft. south of the NE corner ofRosemonte where it connects to an internal pedestrian trail within Tract I. At this point, we would create a new crosswalk -this at the south leg of the 148 111 Avenue/117'11 Street intersection. This new crosswalk would be appropriately marked and signed, following the guidance of your traffic consultant, TENW. Thus would be established controlled pedestrian crossings across all three legs of the intersection. Our conclusion is that this new crosswalk, as proposed, and as opposed to the northward extension illustrated in the attachment to this letter, is a practical solution to the issue of school walkway safety and that an extension to the existing crosswalk to the north -absent concurrent redevelopment of that adjacent parcel, in light of the exceptional construction requirements thereby imposed, and given the unknown cost and availability of needed easements over private property -is not. Please let me know ifwe can be of additional assistance in this matter. Sincerely, '· Buck ·ice President GFB/cy· enclosures King County Road Services Division Department of Transportation KSC· TR-0231 201 South Jackson Street Seattle, WA 98104-3856 March 31, 2008 Sheri Murata 12112-1 lSth Avenue NE Kirkland, WA 98034 0 RE: Road Variance L07V01 l 6 -East Renton/Rosemonte -Related Files L02P00/5 and L03P0018 ----·. ____ ,==..:=..:~ -------~~---~----------·· ------·------ Dear Ms. Murata: Thank you for your application for a variance from the 1993 King County Road Standards (KCRS). You requested a variance from Section 2.02 concerning the design of the shoulder on the east side of 148th Avenue SE. The street at 148th Avenue SE is a collector arterial that the Department of Development and Environmental Services is requiring an eight-foot shoulder on the east side of the road. You propose a thickened edge within the shoulder, with the ditch section eliminated and replaced with pipes and catch basins. The proposed thickened edge section is on the opposite side of the road from the urban plat frontage. Since the applicant is lowering the entire road for 623 linear feet to improve the sight distance along and beyond the plat frontage, the east side of the road must be reconstructed. The KCRS only allows thickened edge roadways on neighborhood collectors ·and local access streets. A thickened edge would not be an appropriate design on an arterial or as proposed within the shoulder section. Shoulders on arterials should allow for cars to pull off the road and provide a "recovery area" adjacent to the traveled way. A thickened edge design is not compatible for vehicular pullover maneuvering. The proposed shoulder does not provide for safe pedestrian use. Per the Public Rule on Procedures for Requesting Variances form the KCRS (PUT 10-2), a variance must produce a compensating or comparable result that is in the public interest. In addition, the variance must produce a result that is safe and functional. Your proposal for a thickened edge fails this test. I respectfully deny the variance request. This decision applies only to KCRS identified in the variance request. All design requirements in the KCRS and other regulations, such as surface water management and zoning, must be satisfied for a land use permit application. The applicant retains the rights and privileges afforded by King County Code and adopted Public Rules pertaining to road variance processing (KCC 14.42, PUT 10-2). Per Section 6.7 of the Public Rule, variance appeals must be made to the Director of the Department of Transportation within thirty days of this variance decision. Sheri Murata March 31, 2008 Page2 A copy of staffs analysis, findings, and conclusions is enclosed. lf you have any questions, please call Craig Comfort, Road Variance Engineer, Traffic Engineering Section, at 206-263-6109. Paulette Norman, P.E. County Road Engineer --------·----, . PN:CC:kc Enclosure --------------~ ·------ cc: James Sanders, P.E., Development Engineer, Land Use Services Division (LUSD), . Department of Development and Environmental Services (DOES) Pete Dye, P.E., Senior Engineer, LUSD, DDES Linda Dougherty, Division Director, Road Services Division (RSD), Department of Transportation (DOT) Matthew Nolan, P.E., County Traffic Engineer, Traffic Engineering Section, RSD, DOT Fatin Kara, P.E., Supervising Engineer, Traffic Engineering Section, RSD, DOT Kris Langley, Senior Engineer, Traffic Engineering Section, RSD, DOT Craig Comfort, P.E., Road Variance Engineer, Traffic Engineering Section, RSD, DOT KingCounty IClng County Road Services Division Department ofTransportatlon Traffic Engineering Section KSC·TR-0222 201 South Jackson Street Seattle, WA 98104-3856 March 31, 2008 TO: Variance File FM: Craig Comfort, P.E., Road Variance Engineer, Traffic Engineering Section -------------- RE: . RoadV ariance I;07VO 116 East ReniontAKA Rosemonte) ..:Reliited:File L02POOOS Ap_plicant's Presentation: 1. A variance is requested for an alternative shoulder design along the east side of 148th Avenue SE, an urban collector arterial. This road is being lowered to enhance sightlines per the plat conditions and per variance L03V0049 for the East Renton Plat. The plat will be providing urban frontage improvements on the west side of the road and is required by the Department of Development and Environmental Services (DDES) to provide an eight-foot shoulder on the east side of the road with the road reconstruction. The applicant proposes a thickened edge section with piped drainage. 2. The applicant will be lowering 623 lineal feet of road to improve the sight distance and this is compensatory to King County. 3. The thickened edge section is proposed because there is an upward sloping bank on the east sid.e of 148th Avenue SE, and a standard design with an eight-foot shoulder and ditch, which would result in grading extending beyond the right-of-way unless a rockery or retaining wall were constructed. The proposed modified section provides 17 feet to 21 feet of pavement east of the centerline which exceeds the existing 12.5 to 18.5 feet of paving. 4. There is no nexus for requiring additional levels of improvement beyond what is practical and that would otherwise restore the roadway to existing conditions. Staff's Findings and Conclusions: 1. Reconstructing a substandard shoulder on the east edge of 148th Avenue SE would open King County up to additional liability. The proposed thickened edge section within the shoulder does not facilitate vehicles pulling off the road or utilizing the shoulder as a recovery area Variance File March 31, 2008 Page2 2. The King County Road Standards (KCRS) requires that an eight-foot shoulder be placed along rural collector arterial. Footnote 8 in Section 2.02 allows an alternative of vertical curb and sidewalk. Turnpike sections are allowed on neighborhood collectors but not arterials. 3. The variance request submittal makes no arguments on safety, functionality, maintainability or that the proposal is comparable to the KCRS. The applicant's proposal appears to be essentially related to cost considerations. ------------- '/ ' REPORT AND DECISION OFFICE OF THE HEARING EXAMINER KING COUNTY, WASHINGTON 400 Yesler Way, Room 404 Seattle, Washington 98104 Telephone (206) 296-4660 Facsimile (206) 296-1654 Email: hearex@metrokc.gov April 10, 2007 SUBJECT: Department of Development and Environmental Services File No. L03POOl8 Proposed Ordinance no. 2007-0011 ROSEMONTE Preliminary Plat Application Location: West of 148th Avenue Southeast at approximately Southeast I 17th Street, Renton Applicant: Cam West Real Estate Dev., Inc. represented by Robert Johns, Attorney Johns Monroe Mitsunaga 1601 -I 14th Ave. SE,# 110 Bellevue, Washington 98004 Telephone: (425) 467-9960 Facsimile: (425) 451-2818 King County: Department of Development and Environmental Services (DDES) represented by Karen Scharer 900 Oakesdale Avenue Southwest Renton, Washington 98055-1219 Telephone: (206) 296-7114 Facsimile: (206) 296-7051 SUMMARY OF RECOMMENDATIONS/DECISION: Department's Preliminary Recommendation: Department's Final Recommendation: Examiner's Decision: EXAMINER PROCEEDINGS: Hearing Opened: Continued for Administrative Purposes: Hearing Closed: Approve subject to conditions Approve subject to conditions (modified) Approve subject to conditions (modified) March 22, 2007 ID) ~ @,~0~2f!~ lJu March 23.'-2® DEC 2 6 2007 L03POO 18~Roscmonte 2 The public hearing on the proposed subdivision of Rosemonte was conducted concurrently with the public hearing on the proposed subdivision of East Renton (DOES File No. L02P0005). Participants at the public hearing and the exhibits offered and entered are listed in the attached minutes. At 12:31 p.m. the hearing was continued for administrative purposes, to allow for the submission of proposed exh. no. 29, providing proposed text for modifications to the department's recommended conditions. Exhibit 29 was received by the Hearing Examiner on March 22, 2007, and the hearing was declared closed on March 23, 2007. A verbatim recording of the hearing is available in the office of the King County Hearing Examiner. ISSUES AND TOPICS ADDRESSED: • • Recreation area Wetland buffers • Surface water drainage SUMMARY: • • Red-tailed hawks nest Safe walking conditions The proposed subdivision of9.35 acres into 25 lots in the urban area is approved subject to conditions. FINDINGS, CONCLUSIONS & DECISION: Having reviewed the record in this matter, the Examiner now makes and enters the following: FINDINGS: 1. General Information: Developer: Engineer: STR: Location: Parcel: Zoning: Acreage: Number of Lots: Density: Lot Size: Proposed Use: Camwest Real Estate Development, Inc. 9720 NE 120th Place, Suite 100 Kirkland, WA 98034 Contact: Sara Slatten 425-825-1955 Triad Associates 12112 115'" Ave NE Kirkland, WA 98034 . Contact: Gerry Buck 425-821-8448 I 0-23-05 West of 148'" Ave SE and south of SE I 17'" St., if extended 1023059395 R-4 9.35 acres 25 Approximately 2.6 units per acre Approximately 5,300 square feet in size Single Family Detached Dwellings L03POOl 8-Rosemonte Sewage Disposal: Water Supply: Fire District: School District: City of Renton Water District# 90 City of Renton Issaquah School District Complete Application Date: July 8, 2003 3 2. Except as modified herein, the facts set forth in the King County Land Use Services Division's preliminary report to the King County Hearing Examiner for the March 22, 2007, public hearing are found to be correct and are incorporated herein by this reference. The LUSD staff recommends approval of this subdivision, subject to conditions. 3. Development of this subdivision may affect, and lead to the abandonment of, a red-tailed hawks nest on the adjacent property to the south (proposed subdivision of East Renton). The red-trailed hawk is not an endangered or threatened species, and no protection of the red-tailed hawk is afforded by law or the King County Code within the designated urban area of King County. 4. The applicant has submitted a revised recreation plan for this subdivision and the adjacent plat of East Renton (exh. no. 26). This plan would provide adequate area within Tract B, a trail adjacent to proposed lot 11, and within Tracts C, G and E and a proposed trail in the adjacent plat of East Renton, to serve these plats jointly with well conceived amenities for recreation and open space, consistent with the requirements of the King County Code. To the extent that a portion of the recreation area necessary to meet the requirements for this plat is located on the East Renton Plat property, that variation from KCC 2 IA.14.180 can be corrected by boundary line adjustment or recording the two plats as a single plat, if ODES determines that it is necessary to do so. 5. Wetland buffers within this subdivision will need to be modified, utilizing the buffer averaging provisions of the critical areas code, to accommodate the proposed alignment of 145th Avenue Southeast in the vicinity of the south property line. 6. The proposed subdivision will provide for safe walking conditions for students who will walk to Apollo Elementary School on southeast 11 7th Street by constructing urban improvements to 148th Avenue Southeast from the plat to Southeast I 17th Street. A school crosswalk (crossing 148th Avenue Southeast) is located on the north side of Southeast I 17th Street, where an existing walkway is used by students to travel along the north side of Southeast I 17th Street, east from 148th Avenue Southeast to the school. This crosswalk also serves students walking from the area north of Southeast I I 7th Street. Consequently, the crosswalk should be maintained north of Southeast I I 7th Street, unless it is physically impractical to do so because of constraints resulting from the topography within the right-of-way for I 48th Avenue Southeast, south of Southeast I I 7th Street. If those constraints preclude extending curb, gutter and sidewalk from this plat to the north side of Southeast I 17th Street, the crosswalk can be relocated to the south, and improvements made on the east side of I 48th Avenue Southeast extending north from the relocated crosswalk to Southeast I 17th Street. 7. The conceptual review of drainage plans has shown that there are no downstream impacts likely to occur from development of the subject property if Level I flow control and basic water quality treatment improvements are designed and constructed in accordance with the 1998 King County L03 POO 18-Rosemonte 4 Drainage Manual. The final drainage plan will include calculations to assure that the capacity of drainage facilities and discharge rates will be consistent with those flow control standards. CONCLUSIONS I. If approved subject to the conditions recommended below, the proposed subdivision will comply with the goals and objectives of the King County Comprehensive Plan, subdivision and zoning codes, and other official land use controls and policies of King County. 2. If approved subject to the conditions recommended below, this proposed subdivision will make appropriate provision for the public health, safety and general welfare, and for open spaces, drainage ways, streets, other public ways, transit stops, potable water supply, sanitary waste, parks and recreation, playgrounds, schools and school grounds and safe walking conditions for students who only walk to school; and it will serve the public use and interest. 3. The conditions for final plat approval recommended below are in the public interest and are reasonable and proportionate requirements necessary to mitigate the impacts of the development upon the environment. 4. The dedications ofland or easements within and adjacent to the proposed plat, as required for final plat approval or as shown on the proposed preliminary plat submitted by the Applicant on March 31, 2006 and the conceptual recreation plan submitted March 22, 2007 (exh. 26), are reasonable and necessary as a direct result of the development of this proposed plat, and are proportionate to the impacts of the development. 5. No provisions are required to be made by this subdivision for the protection of the red-tailed hawks nest( s) on the site. 6. The proposed conceptual recreation plan submitted as exh. no. 26 is a reasonable and appropriate plan to serve the plats of East Renton and Rosemonte jointly. Minor alterations may be made in the final design and review by DOES, and boundary adjustments, if necessary, may be made to comply with provisions of KCC 21 A.14.180-200. 7. Revisions to the wetland buffers will be necessary to comply with the provisions of the King County Critical Areas Code, to permit construction of 145th Avenue Southeast in the vicinity of the south property line. 8. In order to provide for safe walking conditions for students walking from this development to Apollo Elementary School, urban improvements must be made to 148th Avenue Southeast north from the proposed plat to the north side of Southeast I 17th Street. These improvements should be made to the west side of 148th Avenue Southeast to the extent it is feasible to do so. In the event it is not practical to construct improvements extending to the existing crosswalk located at the north side of Southeast I 17th Street, a crosswalk may be established south of Southeast I 17th Street and a safe walkway provided on the east side of 148th Avenue Southeast from the new crosswalk to the north side of Southeast I 17th Street. LOJ POO 18-Roscmontc 9. Calculations for surface water detention facilities shall assure that the release of storm water from the site does not exceed the rates allowed by the 1998 King County Drainage Manual for achieving Level I flow control. DECISION The proposed preliminary plat of Rosemonte as revised and revised and received on March 31, 2006 is approved, subject to the following conditions of final plat approval: 5 I. Compliance with all platting provisions of Title 19A of the King County Code. Actual final recording of the plat of Rosemonte/L03POO 18 shall either occur subsequent to or concurrent with the recording of the Plat of East Renton/L02P0005. 2. All persons having an ownership interest in the subject property shall sign on the face of the final plat a dedication that includes the language set forth in King County Council Motion No. 5952. 3. The plat shall comply with the base density and minimum density requirements of the R-4 zone classification. All lots shall meet the minimum dimensional requirements of the R-4 zone classification or shall be as shown on the face of the approved preliminary plat, whichever is larger, except that minor revisions to the plat which do not result in substantial changes may be approved at the discretion of the Department of Development and Environment Services. Any/all plat boundary discrepancy(ies) shall be resolved to the satisfaction of DOES prior to the submittal of the final plat documents. As used in this condition, "discrepancy" is a boundary hiatus, an overlapping boundary or a physical appurtenance which indicates an encroachment, lines of possession or a conflict of title. 4. The applicant must obtain final approval from the King County Health Department. 5. All construction and upgrading of public and private roads shall be done in accordance with the King County Road Standards established and adopted by Ordinance No. 11187, as amended (1993 KCRS). 6. The applicant must obtain the approval of the King County Fire Protection Engineer for the adequacy of the fire hydrant, water main, and fire flow standards of Chapter 17.08 of the King County Code. All future residences constructed within this subdivision are required to be sprinklered (NFPA 13D) unless the requirement is removed by the King County Fire Marshal or his/her designee. The Fire Code requires all portions of the exterior walls of structures to be within 150 feet (as a person would walk via an approved route around the building) from a minimum 20-foot wide, unobstructed driving surface. To qualify for removal of the sprinkler requirement, driving surfaces between curbs must be a minimum of 28 feet in width when parking is allowed on one side of the roadway, and at least 36 feet in width when parking is permitted on both sides. The road width requirement applies to both on-site access and roads accessing the subdivision. L03 POO 18-Rosemontc G Storm Drainage 7. Final plat approval shall require full compliance with the drainage provisions set forth in King County Code 9.04. Compliance may result in reducing the number and/or location of lots as shown on the preliminary approved plat. Preliminary review has identified the following conditions of approval, which represent portions of the drainage requirements. All other applicable requirements in KCC 9.04 and the Surface Water Design Manual (SWDM) must also be satisfied during engineering and final review. a. Drainage plans and analysis shall comply with the 1998 King County Surface Water Design Manual. DDES approval of the drainage and roadway plans is required prior to any construction. b. Current standard plan notes and ESC notes, as established by DOES Engineering Review shall be shown on the engineering plans. c. The following note shall be shown on the final recorded plat: "All building downspouts, footing drains, and drains from all impervious surfaces such as patios and driveways shall be connected to the permanent storm drain outlet as shown on the approved construction drawings# on file with DDES and/or the Department of Transportation. This plan shall be submitted with the application of any building permit. All connections of the drains must be constructed and approved prior to the final building inspection approval. For those lots that are designated for individual lot infiltration systems, the systems shall be constructed at the time of the building permit and shall comply with the plans on file." d. Storm water facilities shall be designed using the KCRTS level one flow control standard. Water quality facilities shall also be provided using the basic water quality protection menu. The size of the proposed drainage tracts may have to increase to accommodate the required detention volumes and water quality facilities. All runoff control facilities shall be located in a separate tract and dedicated to King County unless portions of the drainage tract are used for recreation space in accordance with KCC 21A.14.180. e. The applicant has received approval for a drainage adjustment application regarding the proposed shared facility detention pond. The adjustment decision is contained within file number L04VOJ03. During final review of the engineering plans, all applicable conditions of the adjustment approvals shall be satisfied. f. As stated in the drainage adjustment decision, the detention pond shall be designed using the Level I llow control standard and basic water quality standards are required for design of the drainage facility. !fa wet pond facility ,s provided for water quality, the design shall comply with the 3: I flow length ratio as outlined on page 6-72 in the drainage manual. L03 POO 18-Rosemontc g. As required by Special Requirement No. 2 in the drainage manual, the I 00-year floodplain boundaries for the onsite wetlands shall be shown on the final engineering plans and recorded plat. Access/Roads 8. The proposed subdivision shall comply with the 1993 King County Road Standards (KCRS) including the following requirements: 7 a. During preliminary review the applicant submitted a road variance application (File No. L06V0042), regarding the sag vertical curve and substandard stopping sight distance along the plat frontage. In response to the variance application, the King County Road Engineer provided a decision letter dated June 20, 2006 which approved the variance based upon required illumination for the sag curve on 148'h Ave SE. The final road improvements and design plans for the project shall demonstrate compliance with all applicable conditions of approval as stated in the variance decision. b. 148'h A venue SE shall be improved along the frontage as an urban collector arterial including all design criteria from the road variance decision. In accordance with KCRS 2.02, the curb location shall be designed at 22-feet from the road crown to provide full width travel lanes and a bike lane. The preliminary design plan for Rosemonte shows road grading extending outside the right-of-way on the east side of 148'h Ave SE. During final engineering review, the applicant shall acquire easements for any proposed construction on private property or provide an alternative design which is acceptable to King County for road construction within the existing right-of-way. If desired by the applicant, the road frontage improvements for Rosemonte may be satisfied by development of the East Renton plat. c. The proposed loop road within the subdivision (SE 118'" St.) shall be improved as an urban subaccess street. d. Tract A shall be improved as a private joint use driveway serving a maximum of two lots. The serving lots shall have undivided ownership of the tract and be responsible for its maintenance. As specified in KCRS 3.0lC, improvements shall include an 18 foot paved surface and a minimum tract width of 20 feet. Drainage control shall include a curb or thickened edge on one side. e. Street trees shall be included in the design of all road improvements and shall comply with Section 5 .03 of the KCRS. f. Street illumination shall be provided along the plat frontage for arterial streets in accordance with KCRS 5.05. g. The proposed road improvements shall address the requirements for road surfacing outlined in KCRS Chapter 4. As noted in section 4.01 F, full width pavement overlay is required where widening existing asphalt. unless otherwise allowed by King County. L03POO 18-Roscmonte 8 h. 148'" Ave SE is classified an arterial street which may require designs for bus zones and tum outs. As speci tied in KCRS 2.16, the designer shall contact Metro and the local school district to determine specific requirements. 1. Modifications to the above road conditions may be considered by King County pursuant to the variance procedures in KCRS 1.08. 9. All utilities within proposed rights-of-way must be included within a franchise approved by the King County Council prior to final plat recording. 10. The plat plan for Rosemonte shows a retaining wall associated with 145 1h Ave SE which extends into the BSBL for the wetland buffer. During engineering review for East Renton, a revised road alignment and grading plan shall be provided which demonstrates that road construction within Rosemonte will comply with applicable sensitive area codes. The revised road design and grading plan may result in modification or loss of lots as shown on the preliminary plat. Alternatively, the applicant may seek approval to use buffer averaging as a means to revise the location of the buffer and BSLB to achieve code compliance. 11. There shall be no direct vehicular access to or from 1481h Ave SE from those lots which abut it. A note to this effect shall appear on the engineering plans and the final plat. 12. Off-site access to the subdivision shall be over a full-width, dedicated and improved road which has been accepted by King County for maintenance. If the proposed access road has not been accepted by King County at the time of recording, then said road shall be fully bonded by the applicant of this subdivision. 13. The applicant shall provide a safe walking access to Apollo Elementary School with urban improvements along the west side of 148 1h Ave NE to the existing crosswalk on the north side of SE 117 1h St. This improvement includes urban frontage improvements along property frontage of the Plat of East Renton, north of SE I 19th Street, as well as urban improvements along frontage of Rosemonte and urban improvements north to the existing crosswalk on the north side of SE 1 I 7'h St. In the event it is not practical to construct urban improvements on the west side of 148th Avenue Southeast extending to the existing crosswalk, a new crosswalk may be established south of Southeast I 17th Street and a safe walkway provided on the east side of 148th Avenue Southeast from the new crosswalk to the north side of Southeast I 17th Street. This alternative may use a graded surface on the east side of 148th Ave SE to ensure that school-age pedestrians are provided an acceptable-width walkway surface behind the curbing. The walkway shall be designed to the satisfaction of the school district and ODES. Mitigation/Impact Fees 14. The applicant or subsequent owner shall comply with King County Code 14.75. Mitigation Payment System (MPS), by paying the required MPS fee and administration fee as determined by the applicable fee ordinance. The applicant has the option to either: (I) pay the MPS lee at the final plat recording. or (2) pay the MPS lee at the time of building permit issuance. If the first LOJPOO 18-Rosemonte 9 option is chosen, the fee paid shall be the fee in effect at the time of plat application and a note shall be placed on the face of the plat that reads, "All fees required by King County Code 14.75, Mitigation Payment System (MPS), have been paid." If the second option is chosen, the fee paid shall be the amount in effect as of the date of building permit application. I 5. Lots within this subdivision are subject to King County Code 21 A.43, which imposes impact fees to fund school system improvements needed to serve new development. As a condition of final approval, fifty percent (50%) of the impact fees due for the plat shall be assessed and collected immediately prior to the recording, using the fee schedules in effect when the plat receives final approval. The balance of the assessed fee shall be allocated evenly to the dwelling units in the plat and shall be collected prior to building permit issuance. Wetlands 16. Preliminary plat review has identified specific requirements which apply to this project as listed below. All other applicable requirements from K.C.C. 21A.24 shall also be addressed by the applicant. a. The Class 2 wetland shall have a minimum 50-foot buffer of undisturbed vegetation as measured from the wetland edge. b. Sensitive area tract(s) shall be used to delineate and protect sensitive areas and buffers in development proposals for subdivisions and shall be recorded on all documents of title of record for all affected lots. c. Buffer width averaging may be allowed by King County if it will provide additional protection to the wetland/stream or enhance there functions, as long as the total area contained in the buffer on the development proposal site does not decrease. In no area shall the buffer be less than 65 percent of the required minimum distance. To ensure such functions are enhanced a mitigation plan will be required for the remaining on-site sensitive areas. An enhancement plan shall be submitted for review during engineering review. d. A 15-foot BSBL shall be established from the edge of buffer and/or the sensitive areas Tract(s) and shown on all affected lots. e. To ensure long term protection of the Sensitive Areas a split-railed fence ofno more than 4 feet in height shall be installed along the Sensitive Area Tract boundaries in the area of proposed lots. Sensitive Area signs shall be attached to the fence at no less than I 00 foot intervals. f. If alterations of streams and/or wetlands are approved in conformance with K.C.C. 21 A.24, then a detailed plan to mitigate for impacts from that alteration will be required to be reviewed and approved along with the plat engineering plans. A performance bond or other financial guarantee will be required at the time of plan approval to guarantee that the mitigation measures are installed according to the plan. Once the mitigation work is completed to a DOES Senior Ecologist's satisfaction, the performance bond may he replaced by a maintenance bond for the remainder of the five-year monitoring period L03POO 18-Rosemontc to guarantee the success of the mitigation. The applicant shall be responsible for the installation, maintenance and monitoring of any approved mitigation. The mitigation plan must be installed prior to final inspection of the plat. 10 g. Prior to commencing construction activities on the site, the applicant shall temporarily mark sensitive areas tract(s) in a highly visible manner, and these areas must remain so marked until all development proposal activities in the vicinity of the sensitive areas are completed. h. During engineering plat review the applicant shall provide a wetland hydrology analysis to demonstrate how the wetland hydrology will be maintained post-construction. 1. Detention out-fall structures maybe permitted within the wetland/stream buffers, however, structures shall be located in the outer edge of the buffer, if possible. All buffer impacts shall be mitigated. 17. Development authorized by this approval may require other state and/or federal permits or approvals. It is the applicant's responsibility to correspond with these agencies prior to beginning work on the site. 18. During engineering review, the plan set shall be routed to the sensitive areas group to determine if the above conditions have been met. Geotechnical 19. The applicant shall delineate all on-site erosion hazard areas on the final engineering plans (erosion hazard areas are defined in KCC 21 A.06.415). The delineation of such areas shall be approved by a DOES geologist. The requirements found in KCC 21 A.24.220 concerning erosion hazard areas shall be met, including seasonal restrictions on clearing and grading activities. 20. The geotechnical work for this project shall be accomplished in accordance with recommendations presented in the geotechnical engineering report dated April 23, 2003 by Associated Earth Sciences, Inc. a. Structural fill placement shall be continuously monitored and approved in writing by the project geotechnical engineer or engineering geologist. b. After excavation and prior to structural fill or foundation placement, all bearing soils shall be inspected and approved in writing by an experienced geotechnical engineer or engineering geologist. c. Structural fill placed for improved areas such as pavements or lloor slabs shall be compacted to at least 95 percent of the maximum dry density by ASTM test designation D-1557 (Modified Proctor) or as recommended by the project geotechnical engineer or engineering geologist. d. All pile foundation installations shall be continuously monitored by a registered gcotcchnical engineer or a licensed engineering geologist for compliance with an L03POO 18-Rosemonte approved plan and the geotechnical report. Compliance and approval of the pile foundation installation shall be documented in a report to the King County site or building inspector. II e. The location and height of any proposed rockeries or retaining walls shall be shown on the engineering plans. f. Any created fill slope that is 40 percent or steeper and IO feet or greater in vertical height shall be subject to a 50-foot wide buffer plus a 15-foot wide setback area from its top, toe and sides. This buffer may be reduced to IO feet with a satisfactory evaluation by a registered geotechnical engineer or licensed engineering geologist. g. The applicant shall delineate all on-site erosion hazard areas on the final engineering plans (erosion hazard areas are defined in KCC 2 IA.06.415). The delineation of such areas shall be approved by a DOES geologist. The requirements found in KCC 21A.24.220 concerning erosion hazard areas shall be met, including seasonal restrictions on clearing and grading activities. Sensitive Area 21. The following note shall be shown on the final engineering plan and recorded plat: RESTRICTIONS FOR SENSITIVE AREA TRACTS AND SENSITIVE AREAS AND BUFFERS Dedication of a sensitive area tract/sensitive area and buffer conveys to the public a beneficial interest in the land within the tract/sensitive area and buffer. This interest includes the preservation of native vegetation for all purposes that benefit the public health, safety and welfare, including control of surface water and erosion, maintenance of slope stability, and protection of plant and animal habitat. The sensitive area tract/sensitive area and buffer imposes upon all present and future owners and occupiers of the land subject to the tract/sensitive area and buffer the obligation, enforceable on behalf of the public by King County, to leave undisturbed all trees and other vegetation within the tract/sensitive area and buffer. The vegetation within the tract/sensitive area and buffer may not be cut, pruned, covered by fill, removed or damaged without approval in writing from the King County Department of Development and Environmental Services or its successor agency, unless otherwise provided by law. The common boundary between the tract/sensitive area and buffer and the area of development activity must be marked or otherwise flagged to the satisfaction of King County prior to any clearing, grading, building construction or other development activity on a lot subject to the sensitive area tract/sensitive area and buffer. The required marking or flagging shall remain in place until all development proposal activities in the vicinity of the sensitive area are completed. No building foundations are allowed beyond the required 15-foot building setback line, unless otherwise provided by law. L03 POO 18-Roscrnonte Recreational Area 12 22. The plat design shall be revised to provide the minimum suitable recreation space consistent with the requirements of K.C.C. 2 IA.14.180 and K.C.C. 2 IA. 14.190 (i.e., minimum area, as well as, sport court[s], children's play equipment, picnic table[s], benches, etc.), as shown on hearing exh. no. 26. Other a. A detailed recreation space plan (i.e., location, area calculations, dimensions, landscape specs, equipment specs, etc.) shall be submitted for review and approval by ODES prior to or concurrent with the submittal of engineering plats. b. A performance bond for recreation space improvements shall be posted prior to recording of the plat. c. Modify the plat, as needed to comply with KCC 21A.14. I 80.F, as shown in hearing exh. no. 26 for the plat of East Renton (ODES File No. L02P0005). 23. A homeowners' association or other workable organization shall be established to the satisfaction ofDDES which provides for the ownership and continued maintenance of the recreation, open space and/or sensitive area tract(s), which combine usage of the recreation area of the plat of East Renton (ODES File No. L02P0005) and this plat, as shown in hearing exh. no. 26 for the plat of East Renton. 24. Street trees shall be provided as follows {per KCRS 5.03 and K.C.C. 21A.16.050): a. Trees shall be planted at a rate of one tree for every 40 feet of frontage along all roads. Spacing may be modified to accommodate sight distance requirements for driveways and intersections. b. Trees shall be located within the street right-of-way and planted in accordance with Drawing No. 5-009 of the 1993 King County Road Standards, unless King County Department of Transportation determines that trees should not be located in the street right-of-way. c. If King County determines that the required street trees should not be located within the right-of-way, they shall be located no more than 20 feet from the street right-of-way line. d. The trees shall be owned and maintained by the abutting lot owners or the homeowners association or other workable organization unless the county has adopted a maintenance program. Ownership and maintenance shall be noted on the face of the final recorded plat. e. The species of trees shall be approved by DOES if located within the right-of-way, and shall not include poplar, cottonwood, soft maples, gum, any fruit-bearing trees, or any other tree or shrub whose roots are likely to obstruct sanitary or storm sewers, or that is not compatible with overhead utility lines. L03 POO 18-Rosemonte 13 f. The applicant shall submit a street tree plan and bond quantity sheet for review and approval by ODES prior to engineering plan approval. g. The applicant shall contact Metro Service Planning at (206) 684-1622 to determine if 148'" Ave SE is on a bus route. If 148'h Ave SE is a bus route, the street tree plan shall also be reviewed by Metro. h. The street trees must be installed and inspected, or a performance bond posted prior to recording of the plat. If a performance bond is posted, the street trees must be installed and inspected within one year of recording of the plat. At the time of inspection, if the trees are found to be installed per the approved plan, a maintenance bond must be submitted or the performance bond replaced with a maintenance bond, and held for one year. After one year, the maintenance bond may be released after DOES has completed a second inspection and determined that the trees have been kept healthy and thriving. t. A landscape inspection fee shall also be submitted prior to plat recording. The inspection fee is subject to change based on the current county fees. 25. The engineering plans for this project shall identify the location of any wells on the site and provide notes which address the requirements for the contractor to abandon the well(s) pursuant to requirements outlined in the Washington Administrative Code (WAC 173-160). SEPA 26. The following have been established by SEPA as necessary requirements to mitigate the adverse environmental impacts of this development. The applicants shall demonstrate compliance with these items prior to final approval. ( I.) To mitigate the significant adverse impact the plat of Rosemonte will have on the intersections of SR 9001148'" Ave SE and SR 900/164'" Ave SE, the applicant shall install, either individually or in conjunction with other development projects in this area, the following improvements at the SR 900/148'" Ave intersection: • A traffic signal, and • Eastbound and westbound left tum lanes The design for the SR 900/148'" Ave intersection improvements shall be approved by the Washington State Department of Transportation (and by King County to the extent such improvements are located in County right-of-way). In addition, at a minimum, the existing entering sight distance looking east for the north and south legs of the intersection (602 feet and 386 feet, respectively) shall not be reduced as part of the intersection improvements. Documentation shall be submitted to show this requirement is met. All construction work associated with the intersection improvements shall be completed between April I" and September 30'". This seasonal restriction shall be clearly shown on the final engineering plans. In lieu of the installation of the above-noted intersection improvements prior to final plat approval, the applicant may post a financial guarantee with WSDOT which assures the installation of these improvements within two years of the recording of Rosemonte. In this L03 POO l 8~Rosemonte event, intersection improvement design must be approved by WSDOT prior lo King County approval of the engineering plans for Rosemontc. 14 If the above-noted intersection improvements have already been made by others prior Io the recording of Rosemonte, or a financial guarantee has been posted by others which assures the installation of these improvements, then the applicant for Rosemonte shall pay a pro-rata share dollar amount to the developer who has made the improvements or "bonded" for the improvements, in an amount proportional to the impacts of Rosemonte. The pro-rata share dollar amount to be paid shall be set by WSDOT, and documentation shall be provided by the Rosemonte applicant to the King County Land Use Services Division to show this payment has been made, prior to final plat recording. The pro-rata dollar amount to be paid shall be based on the following: • The final Rosemonte lot count • The trip distribution for Rosemonte • The total trips contributed to the intersection of SR 900.148'h Ave by the plats of Aster Park (LOOP0024), Stone Ridge 9L99P3008), East Renton (L02P0005), Shamrock (L02P0014), Rosemonte (aka Ironwood -L03P00! 8), Martin (L05P0019) and any future land use applications submitted to King County for which compliance with the King County Intersection Standards (KCC 14.80) is required at either the SR 9001148 1h Ave intersection, or the SR 9001164th Ave High Accident Location. In the event that either King County or WSDOT adopts a formal "latecomer's" system prior to final plat recording, that system may be followed in lieu of the approach described above, at the discretion of the applicant, as long as at a minimum there is a financial guarantee which assures the above-noted intersection improvements will be installed within two years of the date of recording of the plat ofRosemonte. [Comprehensive Plan Policy T-303 and King County Code 21A.28.060A] (2.) Documentation shall be provided to demonstrate to the satisfaction of WSDOT that stopping sight distance (360 feet) is available on the east leg of the SR 900/148'h Ave intersection. The intersection shall be modified by the applicant, if necessary, so that this stopping sight distance requirement is met on the east leg. In addition, the applicant shall clear vegetation within the right-of-way along SR 900, east of 148'h Ave., to maximize the entering sight distance for the north and south legs of the intersection. [Comprehensive Plan Policy T-303 and King County Comprehensive Policy T-303 and King County Code 21 A.28.060A] ORDERED this 10th day of April, 2007. James N. O'Connor King County Hearing Examiner pro rem L03 POO 18-Rosemonte TRANSMITTED this 9th day of April, 2007, to the parties and interested persons of record: Robert L. Anderson PO Box 353 Maple Valley WA 98038 Claudia Donnelly 10415 -147th Ave. SE Renton WA 98059 Ralph Hickman 9720 NE I 20th Pl. # 100 Kirkland WA 98034 Seattle KC Health Dept. E. Dist. Environ. Health 14350 SE Eastgate Way Bellevue WA 98007 Lisa Dinsmore DDES/LUSD MS OAK-DE-0100 Shirley Goll DDES/LUSD MS OAK-DE-0100 Steve Townsend DDES/LUSD MS OAK-DE-0100 Bruce Whittaker DDES/LUSD MS OAK-DE-0100 CamWest Devel., Inc. Attn: Sara Slatten 9720 NE I 20th Pl. # I 00 Kirkland WA 98034 Renee & Mark Engbaum 5424 NE I 0th St. Renton WA 98059-4386 Robert D. Johns Johns Monroe Mitsunaga 1601 -114th Ave. SE,# 110 Bellevue WA 98004 Triad Associates 12112 -I 15th Ave NE Kirkland WA 98034 Peter Dye DDES/LUSD MS OAK-DE-0100 Kristen Langley DDES/LUSD MS OAK-DE-0100 Larry West DDES/LUSD MS OAK-DE-0100 NOTICE OF RIGHT TO APPEAL Kristine & Keith Childs 12004 -148th Ave. SE Renton WA 98059 John Graves Lozier Homes 1203 114th Ave. SE Bellevue WA 98004 Rebecca Lind City of Renton, EDNSP I 055 S. Grady Way Renton WA 98057 Kim Claussen DDES/LUSD MS OAK-DE-0100 Nick Gillen DDES/LUSD MS OAK-DE-0100 Karen Scharer DDES/LUSD MS OAK-DE-0100 Kelly Whiting KC DOT, Rd. Srvcs. Div. MS KSC-TR-0231 15 In order to appeal the decision of the Examiner, written notice of appeal must be filed with the Clerk of the King County Council with a fee of$250.00 (check payable to King County Office of Finance) 011 or before April 24, 2007. If a notice of appeal is filed, the original and six (6) copies of a written appeal statement specifying the basis for the appeal and argument in support of the appeal must be filed with the Clerk of the King County Council 011 or before May I, 2007. Appeal statements may refer only to facts contained in the hearing record; new facts may not be presented on appeal. Filing requires actual delivery to the Office of the Clerk of the Council. Room I 025, King County Courthouse, 516 3'' Avenue, Seattle, Washington 98104, prior to the close of business ( 4:30 p.m.) on the date due. Prior mailing is not sufficient if actual receipt by the Clerk docs not occur within the L03POO J 8~Roscmonte 16 applicable time period. The Examiner does not have authority to extend the time period unless the Office of the Clerk is not open on the specified closing date, in which event delivery prior to the close of business on the next business day is sufficient to meet the filing requirement. Jfa written notice of appeal and filing fee are not filed within fourteen (14) calendar days of the date of this report, or if a written appeal statement and argument are not filed within twenty-one (21) calendar days of the date of this report, the decision of the hearing examiner contained herein shall be the final decision of King County without the need for further action by the Council. MINUTES OF THE MARCH 22, 2007, PUBLIC HEARING ON DEPARTMENT OF DEVELOPMENT AND ENVIRONMENTAL SERVICES FILE NO. L02POOOS James N. O'Connor was the Hearing Examiner in this matter. Participating in the hearing were Karen Scharer, Pete Dye and Kristen Langley, representing the Department; Robert Johns representing the Applicant; and Renee Engbaum. Exhibit No. l Exhibit No. 2 Exhibit No. 3 Exhibit No. 4 Exhibit No. 5 Exhibit No. 6 Exhibit No. 7 Exhibit No. 8 Exhibit No. 9 Exhibit No. I 0 Exhibit No. 11 Exhibit No. 12 Exhibit No. 13 Exhibit No. 14 ODES file L02POOOS DOES preliminary report for L02POOOS, prepared 12/29/2006 with attachments as follow: 2.1. Plat Map w/66 Lot Plat Design 2.2. City of Renton Sewer Availability 2.3. Road Variance/L03V0049 2.4. Surface Water Management Variance/L02V0089 2.5 Surface Water Management Variance/L04VOI03 2.6. Density Calculations w/R-4 zoning 2. 7 Recreation cross section for Tract G (previously labeled Tract C) Application for land use permit no. AO I P007 I received 4/3/2002 Environmental checklist received 4/3/2002 Revised SEPA Mitigated Determination ofNonsignificance, date of revised issuance: 12/29/2006 Affidavit of posting of Notice of Application indicating posting date of 5/3/2002. received by DOES on 5/3/2002 Revised Site plan (66 lot preliminary plat map) received 3/17/2006 Assessor's maps (2) SE 10-23-05 & SW 11-23-05 Revised Level l Downstream Analysis by Triad & Associates, received 11/24/2004 Traffic Impact Analysis by Gary Struthers Associates received 4/3/2002 Request for School Information form from the Issaquah School District, received 4/25/2002 King County Certificate of Water Availability, received 4/03/2002 Vicinity Map for L05P0019, L03POOl8 & L02P0005, prepared by KC staff on 3/19/2007 DDES Field Report and GIS Information dated 5/1/2002 L03POOJ 8-Rosemonte 17 Exhibit No. 15 Exhibit No. 16 Exhibit No. 17 Exhibit No. 18 Exhibit No. 19 Exhibit No. 20 Exhibit No. 21 Exhibit No. 22 Exhibit No. 23 Exhibit No. 24 Exhibit No. 25 Exhibit No. 26 Exhibit No. 27 Exhibit No. 28 Exhibit No. 29 JNOC:gao L03P0018 RPT Revised Wetlands Detennination and Habitat analysis by C. Gary Schulz dated 9/12/2002 Watertype/stream Classification Survey comments from Washington Trout, dated 10/15/2004 Drainage outfall report by Associated Earth Sciences, Inc., dated 9/24/2002 Boundary line adjustment proposal with attached map, dated 5/3/2004 Not entered Response to East Renton Transportation Comments by Gary Struthers Associates, Inc., dated 1/23/2003 Washington State Department ofTranportation comments regarding Traffic Impact Analysis, dated 11/13/2002 Letter from Claudia Donnelly dated 6/13/2003 regarding basin plan, with 2 attachments Note from Claudia Donnelly with attached copy of 11/12/03 newspaper article regarding transportation model City of Renton comments, regarding sewer service, dated 3/28/2002 Revised language for Condition 6 Conceptual recreation plan by Triad Associates Revised preliminary plat received March 22, 2007 Letter from Renee and Mark Engbaum dated March 22, 2007, with attached map indicating the location of their property Revisions to Conditions 20, 21 and 22 . .. ® KJng Cou111ty DEPARTMENT OF DEVELOPMENT ANO ENVIRONMENTAL SERVICES LANO USE SERVICES DIVISION KING COUNTY, WASHINGTON PRELIMINARY REPORT TO THE HEARING EXAMINER March 22, 2007 -PUBLIC HEA~ING AT 9:30 A.M. ODES Hearing Room 900 Oakesdale Avenue Southwest Renton, WA 98057-6212 . Phone: (208) 298-68()0 PROPOSED PLAT OF ROSEMONTE FILE NO: L03P0018 PROPOSED ORDINANCE NO: 2007-0011 A. SUMMARY OF PROPOSED ACTION: This is a request for a subdivision of 9.35 acres into 25 lots for detached single- family dwellings. The proposed density Is 2.6 dwelling units per acre based on · gross area. Based onnel buildable area of 4.64 acres density in the buildabie · area Is 5.39 dwellings per acre. The lot sizes are predomlnalely 5,050. -5,650 square feet. See Attachment 1 for a copy of the proposed plal map. This plat Is adjacent to the Plat of East-Rentlon/L02P0005 which is currently under review by DOES and Is scheduled for hearing concurrently with Rosemonle. B. GENERAL INFORMATION: : Developer: . Engineer. STR: Location: Parcel: Zoning: Acreage: Number of Lots: Density: Lot Size: Proposed Use: · Sewage Disposal: Water Supply: Fire District: School District: Camwest Real Estate Development, Inc. 9720 NE 120°'Place, Suite 100 Klrkland, WA 98034 · Contact Sam Slatten 425-825-1955 Triad Associates 12112115" Ave NE . Kirkland, WA 98034 . ·Contact: Gerry Buck 425-821-8448 10-23:05 West of 148"' Ave SE and south of SE117" St., if extended 1023059395 R-4 9.35 acres· 25· Approximately 2.6 units per acre Approximately 5,300 square feet In size Single Family Detached Dwellings City of Renton Water District # 90 City of Renton Issaquah School District Complete Application Date: July 8, 200.3 C. D. HISTORY/BACKGROUND; The Subdivision Technical Committee (STC) of King County has conducted an on- site examination of the subject property. The STC has discussed the proposed development with the applicant to clarify technical details of the application, and to detennfne the compatlblllty of this project wilh applfcable King County plans, codes. and other official documents regulating this development. As a result of preliminary discussions, the applfcant presented the Technical · Committee with numerous revisions with the most recent plat revision on March 17, 2006. The modifications from·the Initial submittal include: • · Revised entrance to the plat • Revised location of recreational space • Clartflcatlon of the sidewalk Improvements to be constructed along frontage and Within the plal • Adjustment to the.buffer and BSBL lines associated with the on site wetlands. , Revised plat boundaries, eliminating Iha far west portion (2+ acres) from the plat application. Boundary revision was completed under file L04L0055 and recorded unde'r # 20041223900001. The purpose of the boundary adjustment was to separate that portion of the site annexed Into the City of Renton under Ordinance 5147, effective on July 6, 2005. • SWM Adjustment L02V0089 approved allowing the diversion of runoff to a single facility. • Subsequently SWM Adjustment L04V0103 was approved 3/24/05 for shared faclllty ocncept of the northeast corner of East Renton to utilize eastern drainage faclllty In Rosemonte. • Road Variance L03V0049 approved 10/20/2004 for a 620 -foot vertical curve with 455 feet of stopping sight distance, utlllzlng a two-foot target. Addltlonally approved Is the slight grade bnsak (under 1 % ) at .the north end of the· vertical curve. THRESHOLD DETERMINATION OF ENVIRONMENTAL SIGNIFICANCE: Pursuant to the State Environmental Polley Act (SEPA), RCW 43.21 C, the responsible official of LUSD Issued a mltigatmd threshold determination of non- slgnlflcance (MONS) for the proposed development on December 15, 2006. This determlnaUon was based on the review of the environmental checklist and other pertinent documents, nssultlng In the conclusion that the proposal would not cause probable significant adverse Impacts on the environment proyjded mitigations measures are Implemented. Subsequently, staff nscognlzed Incorrect references to other subdivisions and Issued a REVISED MONS on December 29, 2006 referencing the following mttlgatlons: 1. To mitigate the significant adverse Impact the plat of East Renton will have on the Intersections of SR 900/148~ Ave SE and SR 900/164°' Ave SE, the applicant shall Install, either Jndlvldually or In conjunction with other development projects In this area, the following Improvements at the SR 900/148°' Ave Intersection: • A traffic signal, and · • Eastbcund and westbound left turn lanes FILE NO L02P0005 Page2 Intersection imprOvements shall be completed between April 1st and ·SaptefTlber 301h. This seasonal restriction Shall be clearly shown on the final engineering plans. · ·1n lieu of the installation of the above-noted intersection improvements·prlor to final plat approval, the applicant may posl a financial guarantee with WSDOT whld1 assures the installation of t.hese Improvements within two years or the recording of Rosemonte. In this event, Intersection Improvement design must be approved by . WSDOT prior to King County approval of the engineering plans for Rosemonle. If the above-noted Intersect/on lmprove!Tlents have already ~eon made by ottlers. prior to the recording or Rosemonte, or a flnanclal guarantee has been posted by others which assures the installation of these Improvements, then the applicant for Rosemonte shall pay a pro-rata share dollar amount to thEi developer who has made the Improvements or •bonded• for the Improvements, In an amount propCJ/11onaHo the Impacts of Rosemonte. The pro-rata share dollar amount to be paid shall be sel by WSDOT, and dOC\Jmentatlon shall be provided by the Rosemonte applicant to the_ King County Land Use Services. Division to show. this payment has been made, prior to nnal plat. recordjng. The pro--raijl dollar amount to be paid shall be based on the rollowlng: • The final Rosemonte lot count • The trfp distribution for Rosemonte • The total trfps contrfbuh,d to the lnleraection of SR 900.148• Ave by the plats of Aster Park (LOOP0024), Stone Ridge 9L99P3008), East Renton (L02P0005), Shamroclc (L02P0014), Rosemonta (al<e lrllnwood -L03P0018), MartJn · (L05P0019) and any Mure land use eppllcaUons submitted to King County for which compliance with the King County lnteraectlon Standards (KCC 14.BO) Is requ~ed at either the SR 900/148• Ave Intersection, or the SR 900/164" Ave High A~denl Local/on. In the event that either King County or WSDOT adopts a formal 'latecome(s" system prior .to final plat recording, !hat system may be followed In lieu oi the approach described above, at the dlscreUon or the applicant, as long as at a minimum there Is a financial guarantee which ·assures the abovEHlOled intersection improvements will be Installed within lwo years of the date of recording of the plat of Rosemonta. [Comp.rehenslve Plan Polley T-303 and KJng County Code 21A.28.060A] 2. Doeumantatlon shall be provided to demonstrate to the satisfaction of WSOOT that stopping slght'dlstance (360 feet) Is evaMable on 1he east leg of the SR 900/148• Ave lnteraectJon. The lntarsecU<in shall be modified by the applicant, If necessary, so that this stopping sight distance requirement Is met on the east leg. In addlUon, the applicant shell dear ""IJBleUon within the rtght-of-way along SR. 900, 1!3St of 148• Ave., lo maximize Iha enterlng sight distance for1he north and south legs of the Intersection. [Comprehensive Plan Polley T -303 and King County Comprehensive Polley T-303 and King County Code 21A.28.060AJ An envfronmental Impact statement (EIS) was not required as a result of Issuing 1ha MONS. The appeal period for the revised threshold detenmlnatlon ends at the close of business on January 22, 2007. The specific mitigation measures have been Incorporated as part of the applicant's proposal and are Included In the list of recommended conditions of preliminary approval. Agencies, affected Native American tribes and the public are offered the opportunity to comment on or appeal the datenmlnatlon until January 22, 2007.' E. AGENCIES CONTACTED: 1. King Cqunty Department of Natural Resources and Parks: Comments are Incorporated In the discussion In this report regarding wildlife. 2. King County Fire Protection Engineer: Fire protection engineering preliminary approval has been granted subject to the standard code requirements and requirement for sprlnklerlng of homes unless higher standards for road lmprovamants are met. 3. Issaquah School District: The comments from this district have been incorporated Into this report. FILE NO L03P001 B Page 3 F. 4. · · King County Water District #90: The comments from ·this district have been incorporated in.to this report. 5. City of Renton (sewer provider): See Attachment 2. 6. METRO: No response. 7. Washington State Department of Ecology: No response. 8. Washington State Department of Fish and WIidiife: No response. 9. Washington State Department of Natural Resources: No Response 10. Washington State Department of Transportation: The comments from WSDOT have been Incorporated Into tt,e SEPA TD and In U,ls report. NATURAL ENVIRONMENT: 1. Topography: The site slopes from the southeast dpwn to the west and northwest with an overall elevation change.of approximately 35 feet across the -site. Slopes 20-30 percent predominately are In areas north and west of proposed lots. · 2. SoUs: Two types of surfaces soils are found on this site per King County Soil Survey, 1973. · a. The southeast 213rds of the site Is classified as 8.!lQ -Aldetwood gravely, sandy loam; 15-30% slopes. Runoff Is medium and the erosion hazard Is severe. This soil has a severe llmlllltlon for foundations due to slops, and a moderate slippage potential. It has severe llmltalions for septic tank flfter fields due to very slow permeability In the substratum. b. The northwest 113"' of the site Is classified as t.9§-Alderwood gravely; sandy loam; 0'6% slopes.· Runoff is slow and the erosion hazard Is slight. This son type has a moderate limitation for low building foundations due to a · seasonally high water table, and severe llmltalions for septic tsnk filter-fields · due to very slow permeability In the substratum. Soll exploration was preformed by Associated Earth Sciences, Inc. In April of 2003 and geotechnlcal study was prepared Aprtl 23, 2003. This study states that there Is 2-10 feet offill In the area propcsed as Lots 10-16 and the north third of Lots 17 -20. This fill matertal Is not suitable for foundaUon support due to lhe loose state and presence of scattered organic material. The recommendation of the report Is that a. deep foundaUon system be used to support structures. A layer of organic material up to 1.5 feet deep .was also found In the remaining test pits and Is n~t .suitable for foundations. The report recommends that these top soils be removed. Recommendations were also provided to reduce the poten11al for erosion on the site .(see page 10 -11 of the study). 3. Wetland/streams: A watlandfstream report was prepare.d by AJderNW:dated Aprll 28, 2003. The wetland Identified as Wetland A In U,e report is labeled on the 3/8/06 plat plan as Wetland Band Is classified as a Class 2 Wetland. This wetland-is part of a wetland system exceeding one acre in size, 'includes forested area, and is · part of the headwaters of Honey Creek. It Is noted that on tt,e far west side of the wetland Is a seasonal Class 3 stream. -Presence of this stream does not require that · there be additional buffers east of the wetland. Some buffer averaging Is proposed along the east side of the on°slte wetland. The plan for subdivision has been determined not to comply.with sensitive area provisions. A retaining wall west of 145~ Ave. SE prese_ntly is designed with a location in a BSBL. Code does not permit structures In the BSBL, therefore the FILE NO L03P0018 Page 4 applicant will either need to shift the street east so that the retaining wall is outside of the BSBL (this would change the street alignment of 145"' Ave SE) or Instead propose additional buffer averaging In Rosemonte to allow the BSBL to be shifted west. According to the Conservation District maps, the site Is characterized by a high water table. The _site lies within the Honey Creek subbasin of the May Creek drainage basin. 4. Vegetation: The west third of the slte·ls heavily wooded with a second and third-growth mixture of coniferous and broad-leafed trees native to the Pacific Northwest. Within the wetland Itself, there Is predominately Red Alder. The remaining portion of the site (southeast 2/3rds) is primartly covered In pasture grasses. Scattered evergreen/deciduous trees and brush occur In llmfted riumbers. 5. Wlldlffe: Two Red Tall Hawk Nests were Identified back In 2001 on .the East Renton property .. The applicant has·proposed on the most recent plat plan location of lots approximately 220 feet from the nest. Such birds are not listed as ihreatened or endangered species nor are they protected In the Urban Area of King County. Other small birds and animals undoubtedly inhabit.this site; and larger species may visit this site on occasion, however, the population of species is limited due to · · increased nearby development. 6. · Mapped Sensitive Areas: The SenslHve Areas Map Folio Indicates that there Is a wetland which crosses over from this property onto the property to the north and south and area of erosion hazard on the north central portion of the site. G. :NEIGHBORHOOD CHARACTERISTICS: The prope'.!r lies in southeast King County, north of the City of Renton on the west side of 148 Ave SE which provides arterial acces.s to the site. The site is designatad as Urban and is within the urb~n growth boundary. In recent years there have been numerous plats In the local area approved by King County and the City of Renton. This area is in tre_nsitlon from a rural residential area to a low to medium density urban setting. On this site there is an existing residence and detached garage·and other out buildings. The remaining upland portion is manly in pasture. The forested area on the northwest third is the lowest portion of the site and contains the wetland noted in this report. This property and other surrounding property in the Urban area are zoned R-4 (Resldentlai-4 du's per acre). Properties east of 148• Ave SE and north of SE 120• St. are zoned RA-5 (Rural Area-1 du per 5 acres). AddlHonally, these properties are outside the Urban GroWth Boundary. 148"' Ave SE Is a 60 foot public rlght:of way and the full right-of-way is within the Urban Growth Boundary. H. SUBDIVISION DESIGN FEATURES: 1. Lot Pattern and Density: Th_e proposed lot and street layout Is in conformance with Klng County Codes (I.e. KCC 21A and the 1993 Klng County Road Standards. Density caiculatlon for the plat average is 2 .e dwelling units per the gross 9.53 total acres. Base density would allow up to 38 lots (dwelling units) on the property. . Density based on net bulldable area of 4.64 acres calculates to 5.9 dwellings per acre. The minimum allowed density requires development of at least 16 lots. The 25 lots proposed generally range from 5,050 to 5,650 square feet in area. See Attachment 5 for the Density & Dimension Calculation Worksheet for further details. 2. Internal Circulation: Lots will front onto the internal public elreets that provide access within the subdivision, except for two lots which will access off Tract A, a joint use driveway. Street connectlons for Rosemonte are planned which would provide access out of the plat via 145° Ave SE and. 147• Ave SE. Both these avenues FILE NO L03P0018 Page 5 I. ' .connect to. SE 119" St. in the East Renton plat and this street exits out to 1¢81h Ave SE. See the proposed plat layout, Attachment 1 to this report. 3. Roadway Section: As proposed by the applicant, 148" Ave SE frontage will be improved with urban improvements, including curb, gutter. and sidewalks. A road variance was approved allowing an alternative design for sight distance improvement by providing Illumination (see Attachment 3). The East Renton public street planned as SE 119• St. will be improved as a subcollector street. North of SE 119• St. (both in East Renton and Rosemonte), the street system of 145• Ave SE, SE 11a• St and 147" Ave SE wm function and be classified as a subaccess street, rather than a minor access as.labeled on the plat plan. 4. Drainage: The proposed subdivision Includes a storm water detention pond located within Tract C shown on the preliminary site plan. The pond wlll be designed to accommodate drainage for Rosemonte and the northern portlon:of the East Rentar plat To provide a combined storm water pond for both subdivisions, the applicant requested approval for a drainage adjustment to allow a shared facfllty. · As shown In Attachment 4, the drainage adjustment was approved with several design requirements for the pond. The faclllty WIii provide drainage flow control as well as water quality treatment for potential pollutants In the storm water. In accordance with the 1998 King County drainage manual, the drainage facllltles wlll be ·designed for Level 1 flow control and basic water quality treatment. The site is localed within the Honey Creek subbasln which drains to Iha larger May Creek watershed. The King County basin plan for May Creek has evaluated the Honey Creak basin and recommands that future development In this area use the level one flow control standard as shown In the drainage rt:1anua1: A revl~w of the downstream corridor In the Immediate vicinity of Iha project did not idenUfy a•y specffic drainage problems. After construction and acceptance of the detention pond, the drainage facility will be maintained in the future by King County. The Dralnage'Trect C is adjacent to the plat recreation area Tract B. To coll)ply with code for required recreational tracts, the Subdivision Technical Committee (STC) recommands that the recreational tract and storm drainage tracts be combined. TRANSPORTATION PLANS; 1. Transportation Plans: The King County Transportation Plan Indicates that 148• Avenue Southeast (adjoining east boundary) Is designated as a collectcbr arterial. The King County Non-motorized Transportation Plan Indicates 148°' Avenue, Southeast as part of the plan and is to accommodate bicycles as a shared roadway. 2. Subdivision Access: The Rosemonte subdivision will provide urban niad Improvements with curb, gutter, and sidewalk for both the internal roads and frontage Improvements along 148~ Ave SE. During preliminary review of the roadways, King County determined that the existing sag vertical curve along 1481h Ave SE did not inaet design standards. for stopping sight distance. Dua to the substandard road design and the need for Improving the property frontage, the applicant submitted a road variance application to evaluate the design requirements along 148~ Ave SE. As shown In Attachment 3, the road variance was approved by the King County Department of Transportation to allow construction of the frontage improvements provided that lllumlnatlon Is Installed along 1481" Ava SE to provide adequat_e nighttime sight distance within the sag curve. · To provide adequate walking conditions for school children, a sidewalk will al~o be provided along 148" Ave SE which will extend to an existing crosswalk on the FILE NO L03P0016 Page 6 J, ··-· · north side of the intersection at SE 111• Street. Due to the topography and existing road improvements near the crosswalk, the applicant's design for the sidewalk shows a rockery located outside the right-of-way on private property. ·. The applicant has contacted the property owner regarding acquislllon of a road easement: however a final resolution has not been provided at this time. During final engineering. the applicant will need to obtain an easement for construcllon on private property or prepare an alternative walkway design which satisfies the design requirements within Iha existing right-of-way. It is possible that the . applicant could design urban curb and sidewalk Improvements on the east side of 148"' that would meet the safe walkway requirements to the elementary, as well. Access Into Rosemonte will be provided off 148"' Ava SE through the plat of East · Renton. The Eaat Renton planned stub street south may someday provide for a secondary access out to 148"' Ave SE. and will Improve the connectivity between subdMsions. 3. Trefflc Generation: It Is expected that approximately 250 vehicle trips par day . will be generated with full development of the proposed subdivision. This calculation Includes aervlce vehicles O.e .. mell delivery. garbage pick-up, school bus) which may currently serve this nelghbcrho6d, as well as work trips, shopping, etc. 4. Adequacy of Arterial Roads: Thia proposal has been reviewed under the .criteria In King County Code 14.70, Transportation ConcurrencyManagement, 14.80, .Intersection Standards; and King County Code 14.75; Mitigation Payment System. a. King County Code 14.70-Transportation Concurrency Managemenl: The TmnsportaUon Certificate of Concurrency dated June 13, 2003, Indicates that tmnsportaHon Improvements or strategies wllf be In place at the time of development, or that a financial commitment Is In place to complete the Improvements or strategies within six (6) years, according lo RCW 36.70A.070(6). b. King County Code 14:80-Intersection Standards: The existing arterial system requires Improvements to accommodate the Increased traffic volume generated by this proposal. As a result, DOES Issued a MDNS which calls for the _mitigation needed to address the Impacts resultlng from added lraffic onto local Intersections rather than requiring an EIS prior to action on the prellmlnary plat appllcaUon, see Section D of this nsport. The appeal period for the Threshold Determination closes January 11, 2007. c. King County Code 14.75 -Millgetlon Payment System: King C~unty Code 14.75, Mitigation Payment System (MPS), requlras the payment of a traffic Impact mitigation fee (MPS fee) and an administration fee for each slngle-family resldenUal lot or unit created. MPS fees are determined by the zone·1n which the site is located. This site Is In Zone(a) 442 per the MPS/QuartersecUon list. MPS fees may ba paid at the time of final plat recording, or deferred until building permits ara Issued. The amount of the fee wlll be determined by the. applicable fee ordinance al Iha time tha fea is colletjad. PUBLIC SERVICES: 1. Schools: This proposal has bean reviewed under RCW 58 .17 .11 O and King County Code 21A.28 (School Adequacy). a. School Facilities: Students from the proposed plats of East Renton and Rosemont will be served by Apollo Elementary, Maywood Middle, and Liberty High School. As a result of the passage of time (nearly 4 years between the June 2003/Rosemonta Request for School Information and the date of preparation of this staff report) followlng the receipt of the response from the District, the·STC has reconfirmed the school service boundaries by checking FILE NO L03P001 B Page 7 -.... ,... the School District's web site, and the 'service area'/Attendance map pages for each of the applicable schools. · b. School Impact Faes: Currently the Issaquah School District required that an Impact fee per lot be imposed to fund school system Improvements to serve new development within this district. Payment of this fee in a manner · consistent with K.c.c. 21A.43 will be a condition of subdivision approval. c. School Access: Apollo Elementary School is located to the north of the subject subdivision. off of SE 117'" Street. east of 148'" Avenuo SE. According to information provided by the Issaquah School District. students of t~ls age group would be provided bus transportation to the school due to conditions along the walkway route unless sidewalk Improvements would be provided · along 148'" Avenue SE (see Condition 13). The Subdivision Technical Committee (STC) has recommended that. In addition to the urban shoulder Improvements across the frontage of the proposed subdivision, that urban Improvements be provided across the frontage of the abutting (end, related ·by ownership. access and required off-site mitigation) proposed plat of East Renton, DOES File# L02P0005. The existing designated crossing acioss 148'" Avenue SE Is located Immediately off-frontage from the northern subdivision boundary of Rosemonte, therefore, !he STC believes that additional · Improvements -off-site to both plats' frontage -Is necessary to provide adequate walkways for ltlls age group. Such Improvements should m..,t the urban standards for sidewalks and cums due to location on the north i,lde of the l_ntersectlon, the need for a railing. and traffic volumes on 148h Ave SE. Additionally. due to the potential need to construct a curb and guitar section along the east side of 148'" Avenue SE (to re-profile 148h Avenue SE: and maintain the resultant slope grading within exlstlng right-of-way), the $TC recommends that If the project proponent elects to implement this opt/pn, that a graded surface be provided to ensure that school-age padestrlans are provided an acceptable-width walkway surface behind the curbing. Maywood Middle School ls located to the south of the proposed subdivision. on the opposite side of Southeast 128h Street. In the 14400 block of 168'" Avenue SE. Students of this _age group are provided bus transportation to/from the school due to distance and the traffic conditions along any potential walking· routes. The District had requested that a safe waiting area be provided at the Intersection of Southeast 120~ Straet/148th Avenua·SE. The STC racommends In the plat conditions that a level concrete .:pad' be constructed to augment the required sidewalk Improvements at/near the Indicated Intersection. See Condition 8.h. This Improvement will serve the middle and high school-aged residents of both the subject subdivision and the proposed plat of Rosernonte. Liberty High School ls located to the south of the proposed subdivision, on the opposite side of Southeast 128'" Straet, In the 18600 block of Southeast 136th Street Students of this age group are provided bus transportatlon to/from the school due to distance and the traffic conditions along any potential walking routes. The Issaquah School District had requested._ In tts April 2002 response, that a safe waiting area be provided at the Intersection of Southeast 120th Street/148th Avenue SE. The STC recommends In the plat conditions that a level concrete 'pad' be constructed to augment the required sidewalk Improvements at/near the Indicated Intersection. See Condition 8.h. This Improvement will serve the middle and high school- aged residents of both the subject subdivision and the proposed plat of Rosemonte. 2. Parks and Recreation Space: K.C.C. 21A.14 requires subdivisions In the UR and R zone classifications to"etther provide on-site recreation space or pay a fee to the Parks Division for establishment and maintenance of neighborhood parks. At this time. It do.es not appear that the applicant's plan will provide suitable recreation space FILE NO L03PQ018 Page B as required by code. Additionally, there are no nearby parks where. a "fee in lieu" could_ba applied. · In total 9,750 square feet of recreational area Is required (390 square feat per lot). Rosemonte Tract B includes 47,458 s.f.; however all of Tract B currently does not fit · the definition of flat, dry and usable area. Staff estimates that wlih proposed grading there would be at least 20,000 s.f. of area available for active recreation, well over the minimum stan'dard. 'The recreation area·is located on a tract that Is tucked behind lots on the north side of SE 118~ St. The current ~Ian does not specifically show.an access to the recreation area Tract B from SE 118 St.; however staff notes lhat it is the applicant's intent to provide access via a trail over a storm drainage pipe easement between Lots 11 and 12. Thie easement Is currently shown on the preliminary utility plan submitted March · 31, 2006 as a 1 !;i foot wide corrldor. The abutting Tract C proposed for storm· d_etentlon Is a separate tract from the recreation Tract B. The applicant has not Indicated a willingness to combine Tracts B and C or to develop the stormwater tract In oompllance with the provisions of KCC 21.14 .. 160 F. nor has documentation been submitted that shows a preliminary design that addresses the criteria of Subsection F.2. As such, the crlterla of KCC 21.14.180 ·C. would apply to the plat. The STC concluded that this recreailon tract does.not oomply with Subsection· C.4. and 7. This recreation area does not hava good visibility from roads and sidewalks within the plat. Whether Tract B Is centrally located Is arguable, given the tract Is not In the middle of the lot configuration but yet It serves a small plat • so all lots are fairly close to the tract access point on SE 118~ St.. There Is no point within the plat where street frontage or pa.rklng for the recreation tract Is available, except for the trail segment. The STC Interprets Subsection .C.7. to require the street access from street frontage be convenient to residents. The frontage on 148~ Ave SE.does not meet this criterion. The STC determined that there are alternatives available to assure compliance with code for recreation. The applicant should be given the opportunity during engineerlng to document compliance with KCC 21.14:160 F. If unable to meet Subsection F:, the tract should Include frontage on SE 11 a• Ave SE having a minimum frontage of 10% of the regy/red recreation area (9,750 s.f.). An area of 97.5 by 100 feet (9,750 sf) having a perimeter of 395 fee~ would need 39.5 feet of street frontage for code compliance. This modlflcatlon would also provide for a much wider corridor providing (,Jslblllty Into the recreation area from SE 1 rs• St. . 3. Fire Protection: The Certificate of Water Avallablllty from Water District# 90 Indicates that water will be available to th·e site in sufficient quantity to satisfy King County Fire Flow Standards. Prior to ftnal recording of the plat, the water service facilities mus.I be reviewed and approved per King County Fire Flow Standards. All future residences constructed within this subdivision are required to be sprinklered NFPA 13D unles~ the requirement Is removed by the King County Fire Marshal or hls/fler deslgnee. The Fire Code requires all portions of the exterior walls of structures to be within 150 feet ras a person would walk via an approved route around the building) from a minimum 20-foot wide, unobstructed drlving · surtace. To qualify for removal of the sprinkler requirement driving surfaces between curbs must be a minimum of 28 feet in width when parking Is allowed on one side of the roadway, and at least 36 feet In width when parking Is permitted on both sides. FILE NO L03PQO·I B Page 9 K. UTILITIES 1. Sewage Disposal: The applicant proposes to serve the subject subdivision by . public sewer of the City of Renton. The City conditioned the extension of sewer to the requirement that the developer sign ·a covenant alldwing for future annexation of the property into the City. (See Attachment 2). 2. Water Supply: The applicant proposes to serve the subject subdivision from a public water supply and dlstriputlon system managed by Water and District# 90. A Certlflcate of Water Avatlability, dated 02/06/2003, Indicates this district's capablllty to serve the proposed development. Dedication of easements to the district for extension of water mains will be required. L. COMPREHENSIVE AND COMMUNITY PLAN: 1. Comprehensive Plan: This plat ls governed by the 1994 King County Comprehensive plan which designates this area as Urban Residential 4-12 dwelling units per acre. The proposed subdivision Is not In conflict with the pollcles of the Comprehensive Plan. 2. Community Plans: The subject subdivision Is ldcated in the Newcastle Planning Area and does not conflict with the goals, guidelines, and policies of the Community Plan. M. STATUTES/CODES: If approved wtth the recommended condttlons In this report, the proposed development will comply with the requirements of the County and State Plattlng Codes and Statutes, and the Jots In the proposed subdivision will comply with the mlnlmui'n dimensional requirements of the zone district N. CONCLUSIONS: 1. The subject subdivision will comply with the goals and objectives of the King County Comprehensive Plan and will comply with the requiremenhl of.the Subdivision and Zoning Codes and other officlai'land use controls of KJng Co~nty, based on the conditions for final plat approval. 3. Beyond the typical plat requirements, conditions are proposed which would require the applicant to provide design plans end documentation that address the Items below to the satisfaction of ODES: · a. Acquisition of easements from private property owners with property adjacent to 1461h Ave SE are needed to construct road Improvements to 148"' Ave SE. as proposed. Acquisitions Jncludas an easement for a retaining wall to support sidewalk Improvements to the existing crosswi,lk on the north side of at SE 111"' St., and from property owners on the east side of 148"' Ave SE for side slope easements to support the planned , profile/elevation change to 148"' Ave SE. , Urban road improvements on the west side of 148"' Ave SE along the · property frontage north to the north side of SE 1171h Stand also the froptage of East Renton north to. Rosemonte will satisfy the need for safe walkway access to Iha school. Should the applicant be unable to obtain easements, urban road Improvements could feasibly be provided on the. east side of 148"' Ave SE . as a means to eliminate the need for slope easements on the east side of the road and provide an alternative for a safe walking path to the scho~I. FILE NO L03P0018 Page 10 b. Modifications to the plat are needed to comply with KCC 21A.14.180 Subsection F, or Instead Subsection C. to assure minimum requirements of recreation serving the plat are provided. c. Special ·geotechnlcal rocommendetions have been made for plat and building construction due fo the existing natural and fill soils on the site. These recommendations would be Implemented at the time of plat engineering and construction, as well as, building permit application and construction. d. Buffer averaging Is the ·preferred alternative to assure the retaining wall In Rosemonte off 145'" Ave SE is outside of the wetland buffer and BSBL. Should buffer averaging not provide complete relief from buffer and BSBL limitations, then 146'" Ave SE must be shifted east Alignment of 145'" Ave ·sE within East Renton and within Rosemonte should be coordinated to assure proper alignment of 145'" Ave SE between the two plats. e. Given access to Rosemonte Is dependant on the plat.of East Renton, the STC concludes recording of Rosomonte should either occur after 6r conctJrrent with the recording of East Renton -L02P0005. It Is noted that East Rentqn could proceed without Rosemonte, as East Renton could accommodate stem, drainage detention on-site tt need. o. ,RECOMMENDATIONS; .It Is recommended that the subject subdivision preliminary plat, revised and received Maro~ 31, 2006, be granted prallmlnary approval, subject to the following · rnvisions to the plat deslgr and conditions of final approval: 1. Compliance wllh all platting provisions of Tille 19A of the King County Code. Actual final recording of the plat of Rosemonte/L03P0018 shall either occur subsequent to or concurrent with the recording or the Plat of East Renton/L02P0005. 2. All persons having an.ownership Interest In the subject property shall .sign oh the face of the final plat a dedication that Includes the language set forth in Klng County Council Motion No. 5952. 3. The plat shall comply with the base density and minimum density requirements of the R-4 zone classlflcatlon. All lots shall meet the minimum dimensional requirements of the R-4. zone classlflcatlon or shall be shown on the face of the approved prellm.lnary plat, whichever is larger, except that minor revisions lo the plat which do not result In substantial changes·may · be approved et the discretion of the Deparbnent of Development and Environment Services. · Any/all plat boundary discrepancy shall be resolved .to the satisfaction of DOES prior to the submittal of the final plat documents. As used in this condition, "discrepancy' Is a boundary hiatus, an overlapping boundary or a physical.appurtenance which Indicates an encroachment, lines of possession or a conflict of title. 4. The applicant must obtain final approval from the King County Health Department. 5. All construction and upgrading of pubttc and private roads shall be done in accordance with the King County Road Standards established and adopted by Ordinance No. 11187, as amended (1993 KCRS). FILE NO L03P0018 Paga 11 6. The applicant must obtain the.approval of the King County Fire Protection Engineer for the adequacy of the flre hydrant, water main, and fire flow standards of Chapter 17.08 of the King County Code. Storm Drainage . 7. . Final plat approval shall require full compliance with the drainage provisions set forth In King County Code 9.04. Compliance may result In reducing the number and/or location of lots as shown on the preliminary approved plat. Preliminary review has identified the following conditions of approval, which represent portions of-the drainage requirements. All other applicable requirements In KCC 9_.04 and the Surface Water Design Manual (SWDM) must also be satisfied during engineering and final review. a. Drainage plans and analysis shall comply with the 1998 King County Surface Water Design Manual. ODES approval of the drainage and roadway plans Is required prior to any construction. b. Current standard plan notes and ESC notes, as established by DOES Engineering Review shall be shown on the engineering plans. c. · The following note shall be shown on the final racorded plat: "All building downspouts, footing drains, and drelns from all lmpervlou~ surfaces such as patios and driveways shall be connected to the pamJanent storm drain outlet as shown on the approved construction drawings # on file with DOES and/or the Department of Transportation. This plan shall be submitted with the application of any building permit. All connections of. the drains must be constructed and approyed prior to the final buUdlng Inspection approval. For those lots that are designated far indlvfdua! lot Infiltration systems, the systems shall be constructed at tile time of the building permit and shall comply with the plans on file.• d; .Storm water facillUes shall be designed using the KCRTS level one flow control standaril. Water quality facilities shall also be provided using the basic water quality protection menu. The size ol the proposed drainage tracts may have to lncraase to accommodate the required detenUon volumes and water quality facllltles. All runoff control facllltles shall be located In a separate tract and dedicated to King County unless portions of the drainage tract are used for recreation space In accordance with KGC 21A.14.180. e. The applicant has received approval for a drainage adjustment application regarding the proposed shared facility detention pond. The adjustment decision Is contained within file number L04V0103. Ou ring final review of -the engineering plans, all applicable conditions of the adjustment approvals shall be satisfied. f. As stated In the drainage adjustment decision, the detention pond shall be designed using the Level 1 flow control standard and ·basic water quality standards are required for design of .the drainage facility. If a wet pond facility is provided for water quality, the design shall comply with the . 3:1 flow length ratio as outlined on page 6-72 In the drainage manual. g. As required by Special Requirement No. 2 In the drainage manual, the 100-year floodplain boundaries for the onslte wetlands shall be shown on the final engineering plans and recorded plat. Access/Roads . 8. The proposed subdivision shall comply with the 1993 King County Road Standards (KCRS) including Iha following requirements: FILE NO L03P0018 Page 12 a. During preliminary review the applicant submitted a road variance application (File No. LOBV0042), regarding the sag vertical curve and substandard ·stopping sight distance along the plat fr_ontage. In response to the variance application, the King County Road Engineer provided a decision letter dated June 20, 2006 which approved tho variance based upon required Illumination for· the sag curve on 148'' Ave SE. The final road improvements and design plans for the project shall demonstrate compliance with all applicable conditions of approval as stated in the variance decision. b. 148~ Avenue SE shall be Improved along the frontage as an urban collector arlerlal-lncludlng all design criteria from the road variance decision. In accordance with KCRS 2.02, the c;urb locaUon shall be designed at 22- feet from the road crown to provide full width travel lanes and a bike lane. The preliminary design plan for Rosemonte shows road grading exten~ing outside the right-of-way on the east side of 148~ Ave SE. During final engineering review, the applicant shaH acquire easements for any proposed construction on private property or provide an alternative design which Is acceptable to King County for road construction within the existing right-of-· way. If desired by the applicant, the road frontage Improvements for Rosemonte may be satlsfled by development of the· East Renton plat. c. The proposed loop road within the subdivision (SE 118~ Sl,) shall be Improved as an urban subaccess ·street d. Traci A shall be Improved as a private Joint use driveway serving a maximum of two lots. The serving lots shall have undivided ownerahip of the tract and be responsible for Hs maintenance. As specified In KCRS 3.01 C, Improvements shall Include an-18 foot paved surface and a minimum tract width of 20 feet. Drainage oontrol shall Include a curb or Ulickened edge on one side . . e. Street trees shall·be included In the design of all road Improvements and shall comply with Section 5.03 of the KCRS. f. Street Illumination shall be provided along the plat frontage for arterial streets in acoordanca with KCRS 5. 05. g. The proposed road Improvements shall address the requirements for . road surfacing outlined In KCRS Chapter 4. As noted In section 4.01 F, full width pavement overlay is required wh8re widening e~sting asphalt, unless otherwise allowed by King County. h. 148~ Ave SE Is classified an arterial street which may require designs for bus zones and tum outs. As specified In KCRS .2.16, the· designer shall oontacl Metro and the local scho.ol district to determine specific requirements. ·1. Modifications to the above road condltlons may be considered by King.County pursuant to the variance ·procedures in KCRS 1.08. 9. All utilities within proposed rights-of-way must be Included within a franchise approved by the King County Council prior to final plat recording. 10. The plat plan for Rosemonte shows a retaining wall associated with 145~ Ave SE which extends Into the BSBL for the wetland buffer. During engineering review fo\-East Renton, a revised road alfgnment and grading . plan shall be provided which demonstrates that road construction within Rosemonte will oomply with applicable s.ensltive area codes. The revised road design and grading plan may result In modiflcatlon or loss of lots as shown on the preliminary plat. Alternatively, Iha applicant may seek FILE NO L03P001B Page 13 approval to use buffer averaging as a means to revise the location of the buffer end BSLB to achieve code compliance. 11. There shall be no direct vehicular access to or from 148"' Ave SE from those lots which abut It. A note to this effect shalt appear on the engineering plans and the final plat. 12. Off-site access to the subdivision shall be over a full-width, dedicated and improved road which has been accepted by King County for maintenance. If the proposed access road has not been accepted by King County at the time of recording, then said road shalt be fully bonded by the.applicant of thls·subdivlsion. 13. The applicant shalt provide a safe walking accessto Apollo Elementary · School with urban improvements along the west side of 148"' Ave NE.to the existing crosswalk on the north side of SE 117"' St. This Improvement Includes urban frontage Improvements along property frontage of the Plat of Rosemonta, urban Improvements to the cro59watk on the north side of SE 117"' St. It Is noted that the adjoining plat of East Renton will be subject to urban frontage requirements and extension of safe walkway Improvements to the existing crosswalk on the north side of SE 117h ST. Alternatively, due to the potential need to·construct an urban curb and gutter section along the east side of 148'" Avenue SE (to re-pmflla 148h Avenue SE, and maintain the resultant slope grading within existing right-of-way), the applicant may elect to provide a graded surface on the east side of 148h Ave SE to ensure that school-age pedestrians are provided an acceptable-width walkway surface behind the curbing. The safe walkway shall be designed to the satisfaction of the school district and DOES. · Mitigation/Impact Fees 14. The appltcanlor subsequent owner shall comply with King County Coda 14.75, Mitigation Payment System (MPS), by paying the required MPS fee and administration fee as determined by the applicable fee ordinance. The applicant has the option to either: (1) pay the MPS fee at the final plat recording, or (2) pay Iha MPS fee at the time of building penmlt Issuance. If the first option is chosen, the fee paid shall be the fee In affect at the time of plat application and a note shalt be placed on the face.of the. plat that reads, 'All fees required by Klng County Code 14.75, Mitigation Payment System (MPS), have been paid." If the second oi$)n Is chosen, the fee paid shall be the amount In effac\ as of the date of building panmlt application. 15. Lots within this subdivision are subject to King County Coda 21A.43, which Imposes Impact fees to fund school system Improvements needed to serve new development. As a condition of final approval, fifty percent (50%) of the impact fees due for the plat shall be assessed and collected immediately prior to the recording, using the fee schedules In effect when the plat receives final approval. The balance of the assessed fee shall be allocated evenly to the dwelling units In the plat and shall be collected prior to building penmlt Issuance. Wallands- 16. Preliminary plat review has identified specific requirements which apply to this project as listed below. Ail other applicable requirements from K.C.C. 21A.24 shalt also be addressed by the applicant. a. The Class 2 wetland shalt have a minimum 50-foot buffer of undisturbed vegetation as measured from the wetland edge. FILE NO L03P0018· Paga 14 b. Sensitive area tract(s) shall be used to delineate and protect sensitive areas and buffers In development proposals for subdivisions and shall be recorded on all documents of title of record for all affected lots. c. Buffer width averaging may be allowed by King County if it will provide additional protection to the wetland/stream or enhance there functions, as long as the total area contained in the buffer on the development propcsal site does not decrease, In no area shall the buffer be less than 65 percent of the required minimum distance. To ensure such functions are enhanced e mitigation plan will be required for tho remaining on-site sensitive areas. An enhancement plan shall be submitted for review during engineering review. d. A 15-foot BSBL shall be established from the edge of buffer and/or the sensitive areas Tract(s) and shown on all affected lots. e. To ensure long term protection of the Sensitive Areas a split-railed fence of no more than 4 feet In height shall be Installed along the Sensitive Area Traci boundaries In the area of proposed lots .. SenslUve Area signs shall be attached to the fence al no less than 100 foot 1.nteivals. t · If alterations of streams and/or wetlands are approved In confonnance with K.C.C. 21A.24, then a detailed plan to mitigate for impacts from.that alteration wm be required lo be reviewed and approved along wtth Iha plat engineering plans. A perfonnance bond or other financial guarantee will be required at the time of plan approval to guarantee that lhe mitigation measures are lnstslled according to the plan. ·Once the mitigation work is completed to a ODES Senior Ecologist's satisfaction, the perfonnance bond may be replaced by a maintenance bond for the remainder of the five-year monitoring period to guarantee the success of the mitigailon. The applicant shall .be responsible for the Installation, maintenance and monitoring of any approved mitigation. The mitigation plan must be installed prior to final Inspection of the plat. g. Prior to commencing construction actMUes on the site, the applicant shall tempcrarlly mark sensitive areas tract(s) in a highly visible manner, and these areas must remain so marked until all development proposal activities In the vicinity of the sensitive areas are completed. h. During engineering plat review the applicant shall provide a wetland. hydrology analysis to demonstrate how the wetland hydrology will be maintained post-construction. i. Detention out-fall structures maybe pennitted within the weUand/stream buffers, however, structures shall be located In the outer edge of Iha. buffer, if possible. All buffer Impacts shall be mitlgated .. 17. Development authorized by this approval may require other state and/or federal pennlts or approvals. It Is the applicant's responslblllly to correspcnd with these agencies prior to beginning work on lhe site. 18. Durtng engineering review, the plan set shall be routed to the sensitive areas group to determine If the above conditions have been met. Geotechnfcal 19. The applicant shall deUneale all on-site erosion hazard areas on the final . engineering plans (erosion hazard areas are defined in KCC 21A.06.415). The delineation of such areas shall be approved by a DOES geologist. The requirements found In KCC 21A.24.220 concerning erosion hazard areas FILE NO L03P0018 Page 15 shall be met, including seasonal restrictions on clearing·and grading activities. 20. The. geotechnical work for this project shall be accomplished In accordance with recommendations presented In the geotechnlcal engineering report dated April 23, 2003 by Associated Earth Sciences, Inc. a. Structural fill placement shall be continuously monitored and approved In writing by the project geotechnlcat engineer or engineering geologist. b. After excavation and prior to structural fill or foundation placement, all· bearing soils shall be Inspected and approved In writing ·by an experienced geotechnlcal engineer or engineering geologist. c. Structural fill.placed for Improved areas such as pavements or floor slabs shell be compacted to at least 95 percent of the maximum dry density by ASTM test designation D-1557 (Modified Proctor) or as recommended by the project geotechnlcal engineer or engineering geologist. d. All pilO"foundati.on installations shall be continuously monitored by a registered geotechnlcal engineer or a licensed engineering geologist for compliance with an approved plan and the geotechnlcar report. Compliance · and approval of the pile foundation Installation shall be documented In a report to the Klng County site or buJJ.ding Inspector. e. The location and height of any proposed rockeries or retaining walls shall be shown on the engineering plans. f. Any created fill slope that is 40 percent or steeper end 1 O feet or greater In vertical height shall be subject to a 50-foot wide buffer plus a 15· foot wide setback area from Its top, toe and sides. This buffer may be · reduced to 10 feet with a·satlsfactory evaluatlcn by a registered geotechnlcal engineer or licensed engineering geologist. g. The eppllcent 9hall delineate all on-site erosion hazard areas on the · flnal engineering plans (erosion hazard areas are defined In KCC 21A.06A15). The delineation of such areasshall be approved by a Dc:IES geologist The requirements found In Kee 21A.24.220 ooncemlng er<J!ilon hazard areas shall be met, including seasonal restrictlcns on clearing i,nd grading activities. Sensitive Area 21. · The following note shall be Shown on the final engineering plan and recorded plat: RESTRICTIONS FOR SENSITIVE AREA TRACTS AND SENSITIVE AREAS AND BUFFERS Dedication of a sensitive area tract/sensitive area and buffer conveys to the publlc a beneficial Interest In the land within the tract/sensitive area and buffer. This Interest Includes the preservation of native vegetation for all purposes that benefit the public health, safety and welfare, Including control of surface water and ' erosion, maintenance of slope stability, and protection ·of plant and anlrrial habitat. . The sensitive area tract/sensitive area and buffer Imposes upon all present aM future owners and occupiers of the land subject to the tract/sensitive area encl buffer the obllgatlon, enforceable on behalf of the public by King County, to leave undisturbed all trees and other vegetation within the tract/sensitive area and buffer. The vegeiation within the tract/sensitive area and buffer may not be cut, pruned, covered by fill, removed or damaged without approval In writing from the King FILE NO L03P0018 Page 16 County Department of Development and Environmental Services or its successor agency, unless otherwise provided by law. The common boundary between the tract/sensitive area and buffer and the area of development activity must be markod or otherwise flagged to tt1e satisfaction of King County prtor to any clearing, grading, building construction or other development activity on a lot subject to the serisitivo area tract/sensitive area and buffer. The required mµrklng or flagging shall remain in place until all development proposal activities in the vicinity of the sensitive area are completed. No building foundations are allowed beyond the required 15-foot building setback line, unless otherwise provided by law. · Recreational Area 22. The plat design shall be revised to provide the minimum suitable recreation space consistent with the requirements of K.C.C. 21A.14. 180 and K.C.C. 21A. 14.190 (I.e., minimum area, as well as, sport court[s], children's play equipment, picnic table[s], benches, etc.). Other a. A detailed recreation space plan (I.e., location, area calculations, dimensions, landscape specs, equipment specs, etc.) shall be submitted fur 'review and approval by DOES prior to or concurrent with the submittal of engineering plats. b. A performance bond for recreation space Improvement;; shall be posted pr/or to recording of the plal c. Modify the plat, as needed, to comply with KCC 2JA.14.180 Subsection F, .l!tltl!ot, Instead comply with Subsection C. by locating a 39.5 foot wlde ,,\,tk'frontage on SE 118~ SE to assure that the minimum 10% ' frontage requirement Is meet. . . • 23. A homeowners' association or other workable organization shall be established to the satlsfllctlon of ODES which .provides for the ownerahlp and continued maintenance of the recreation, open space and/or sanslUve area tract(s). 24. Street trees shall be provided as follows (per KCRS 5.03 and K.C.C. 21A.16.050): . a. Trees shall be planted at a rate of one tree for every 40 feet of frontage along all roads. Spacing may be modified to accommodate sight distance requirements for drtveways and Intersections. b. Trees shall be located within the street rtght-of-way and planted In accordance with Drawing No. 6-009 of the 1993 King County Road Standards, unless King Courrty Department of Transportation determines that trees should not be located In the street right-of-way. c. If King County determines that tha required street trees should not be located within the right-of-way, they shall be located no more than 20 feet from the street right-of-way line. d. The trees shall be owned and maintained by the abutting lot owners orthe homeowners association or other workable organization unless the county has adopted a maintenance program. Ownership and maintenance shall be noted on the face of the final recorded plat. FILE NO L03P0018 Page 17 SEPA e. The species of trees shall be approved by ODES ff located within the right-of~way, and shall not Include poplar. cottonwood, soft maples, gum, any fruit-bearing trees, or any other tree or shrub whose roots are likely to obstruct sanitary or storm sewers, or that Is not compatible with overhead utility lines. f. The applicant shall submit a street tree plan and bond quantity sheet for review end approval by DOES prior to engineering plan approval. g. The applicant shall contact Metro Service Planning at (206} 684-1622 to determine ii 148• Ave SE is on a bus route. If 148• Ave SE is a bus route, the street tree plan shall also be reviewed by Metro. h. The street trees must be Installed and inspected, or a performance bond posted prior to recording of the plat. If e performance bond Is posted, the street trees must be Installed and Inspected within one year of recording of the plat. At the time of Inspection, ff the trees are found to be Installed per:the approved plan, a maintenance bond must be submitted or the performance bond replaced with e maintenance bond, and held for one year. After one year, the maintenance bond may be released after DOES has completed a second Inspection and determined that the trees have been kept healthy and thrlvlng. i.. A landscape inspection fee shall also .be submitted prior to plat recording. The lnspectlon fee Is subject to change based on the current county fees. · 25. The following have been established by SEPA as necessary requirements to mitigate the adverse environmental Impacts of this development. The appllcanta shall demonstrate compliance with these items prior to final approval. (1.) To mitigate the significant adverse Impact the plat of Rosemonte will have on .the Jnteraectlons of SR 900/148~ Ave SE and SR 900/184• Ave SE, the applicant shall Install, either indMdu,lly or In conjunction with other development projects in this area, the following Improvements at the SR 900/148• Ave Intersection: • A traffic slgnal, and • Eastbound and westbound left turn lanes The design for the SR 900/148• Ave lnteraection improvements shall be approved by the Washington State Department of Transportation (and by King County,to the extent such Improvements are located In County rtght-of-way). In addition. at a minimum, the existing enterlng sight distance looking east ror the norih and south legs of the lntersecllon (802,feet and 386 feet, respectively) shall not be red~ced as part of the l~tersectlon Improvements. Oocumentatlon shall be submitted. to show this requirement Is met. All oonstructlon work associated with the · lnteraectlon Improvements shall be completed between Apr111• and September 30 11 , This seasonal restnctlon shall be clearly shown on the final engineering plans. In lieu of the Installation of the above-noted Intersection Improvements prt~r to final plat approval, the applicant may post a financial guarantee with WSDOT which assures the Installation of tnese Improvements within two years of the recorctlng of Rosemonte. ln this event, Intersection Improvement design must be approved by WSDOT prior to King County approval of the engineering plans for Rosemonte. If the above-noted Intersection Improvements have already been made by olherS prior to the recording of Rosemonte, or a financial guarantee has been posted by others which assures tho Installation of these Improvements, then the applicant for Rosemonte shall pay a pro-rata share dollar amount lo the developer who has made the" Improvements or 'bonded' for the Improvements, In an amount proportional to the Impacts of Rosemonte. The pro-rata share dollar amount to be paid shall be set by WSDOT, end documentation shall be provided by the FILE NO L03P0018 Page 18 Q. Rosemonte applicant to the King County Land Use SalVices Division to show this payment has been made, prior to final plat recording. The pro-rata dollar amount to be paid shall be based on the following: · • The final Rosemonte lot count • The trip distribution for Rosemonte , The total ~lps contributed to the intersection of SR 900.148• Ave by the plats of Aster Park (LODP0024), Stone Ridge 9L99P3008), East Renton (L02P0005), Shamrock (L02P0014), Rosemonte (aka Ironwood -L03P0018), Martin (L05PD019) and any future land use applications submltlad to King County for which compliance wilh the King County Intersection Standards (KCC 14.80) is required at either the SR 90011~8" Ave intersection, or the SR 900/164• Ave High· Accident Location. tn the event that either King County or WSDOT adopts a formal "latecomer's" system prior to final plat recording, that system may be followed in lieu of the approadl described above, at the discretion of the applicant, as long as at a mfnlmum there Is a financial guarantee which assures the ebove--noted Intersection Improvements wlll be Installed within two years of lhe date of recording or the plat of Rosemonte. [Comprehensive Pian Polley T ·303 and King County Code 21A.28.060A] (2.) Documentation shall be provided to demonstrate to Iha saUsfactlon'ofWSDOT that stop,!'ing sight distance (360 feet) Is available on the east leg of the SR 900/148 Ave intersection. The Intersection shell be modlfll>d by the applicant, if necessary, so that ihis stopping sight distance requirement is met on the east leg. In addiUon, the e~licant shall clear vegetation within the right-of-way along SR 900, east of 146 Ave., to .maximize the entering sight distance for the north and south legs of the intersection. [Comprehensive Plan Polley T-303 and King County Comprehensive Polley T-303 and King County Code 21A.2B.060AJ OTHER CONStDERATJONS: 1. The subdivision shall conform to K.C.C. 16.82 relating to grading on private property. 2. Development of the subject property may require registration with the Washington State. Department of Licensing, Real Estate Division. 3.. Prelimlna,y approval of this application does not limit the applicant's responsibility to obtain any required permit or license from the Stale or other regulato,y body. This may include, but Is not iimlted to the following: . . . a. Forest Practice Permit from the Washington State Department of Natural Resources. b. National Pollutant Discharge Ellmlnatlon System (NPDES) Permit fromWSDOE. c. Water Quality Modification Permit from WSDOE. d: Water Quality Certification (401) Permit from U.S. Army Corps of .Engineers. R. AlTACHMENTS: 1. Plat Map 2. Renton Sewer Availability letter 3. Road Varlance/L06V0042 4. Surface Water Management Variance/L04V0103 5. Density Calculation Worksheet FILE NO L03P0018 Page 19 KiilIBg CouI111ty Department of Development and Environmental Services REVISED State Environmental Policy Act (SEPA) Mitigated Determination of Nonsignificance for Rosemonte/ L03P0018 Date of Revised Issuance: December 29, 2006 Date of Issuance: December 15, 2006 Project: Location: AppllcantJContact: King County Contact: King County Permits: This Is a request for a subdivision of 9.35 acres Into 25 lots for detached slngle•famlly dwellings. The proposed density Is 2.6 dwelllng units per acre. The lot sizes are predomlnately 5,050 -5,650 square feet. West of 1481h Ave SE and south of SE 11ih St., if extended Camwest Real Estate Development, Inc. 9720 NE 1201h Place, Suite 100 Kirkland, WA 98034 Contact: Sara Slatten Phone# 425-825-1955 Karen Scharer, Project/Program Manager II Phone# 206·296·7114 or email at karen.scharer@metrokc.gov Formal Subdivision Existing Zoning: R-4 Community Plan: Newcastle Basin: May Creek Section/Township/Range: 10-23.05 Parcel# 102305 9395 Notes: The mitigations have been revised to reference the subject plat of Rosemonte rather than the previous Incorrect reference to East Renton and other plats. A. This finding Is based on review of the site plan showing the revised proposed development received 3/31/2006; SEPA Environmental Checklists, dated 9/17/2004; Level 1 Drainage Analysis Preliminary Storm Analysis by Core Design .• dated 3/2003; Traffic Impact Analysis by Garry Struthers Associates, Inc., received 6/10/2003; WSDOT correspondence of 2/27/2003 and 3/14/2003; Certificate of Water Availability. dated 2/6/2003; Updated Certificate of Sewer Availability, dated 6/10/2003; and, Wetlands Study by AlderNW dated 4/28/2003. B. Issuance of this threshold determination does not constitute approval of the formal subdivision. The application will be reviewed for compliance with all applicable King County Comprehensive Plan Policies and King County Codes which regulate development activities, including the Uniform Fire and Road Standards, Surface Water Design Manual, and the Sensitive Areas Regulations. C. The Residential designation on the Land Use Map of the King County Comprehensive Plan allows for the proposed density. Additionally, this density is within the range per the R-4 Zone. The plat with 25 lots would yield an average density of 2.6 dwellings per acre (based on the site area). The lots will mostly be 50 feet by 103-113 feet with about 5,050 -5,650 square feet. L03P0018 / REVISED SEPA TD December 29, 2006 Page 2 D.. The subject property is located southwest of the intersection of State Route 900 and 148 1' Ave. SE. According to the applicant's traffic analysis, this intersection will operate at Level-of- Service 'F" following the development of the proposed plat (unless improvements to the intersection are made). Per the applicant's traffic analysis, approximately 51 % of the P.M. peak hour trips from the proposed plat will pass through this intersection. The proposed plat will have a significant adverse Impact on.this intersection per KCC 14.80.030. E. A horizontal curve exists on the east leg of the SR 900/148" Ave SE Intersection.· Bas13d on data provided by the traffic engineer for the plat of Shamrock, which was reviewed by the Washington State Department of Transportation (WSDOT), the available stopping sight distance on the east leg of the intersection meets the standards of the Washington State Highway Design Manual. F. WSDOT has concluded that, based on turn lane warrants from the Washington State Highway Des19r Manual, eastbound and westbound left turn lanes should be constructed on SR 900 at the 148 Ave. Intersection. The proposed plat will add vehicular trips to the hazardous westbound left turn movement at this Intersection. G. In order to address traffic Impacts from the proposed plat, WSDOT has requested that the applicant (along with other development projects that will contribute traffic to the SR 900/146" Ave. intersection) improve this intersection with a traffic signal and eastbound and westbound left turn · lanes. H. The intersection of SR 900/164" Ave SE Is located approximately one mile east of the subject property. This Intersection of SR 900/164" Ave SE. is located approximately one mile east of the subject property. This intersection has been identified by WSDOT as a High Accident Location, and lies within a High Accident Corridor. The subject plat will contribute approxlmately 1 O peak hour trips to this intersection and WSDOT and the King County Department of Transportation have com;luded that the subject plat will have a significant adverse Impact at the . intersection. The Installation of a traffic signal at the 148" Ave. SE/SR 900 Intersection will mitigate the impact of the proposed plat on the 164" Ave. intersection, by diverting traffic away from the 164111 Intersection to the 148th Intersection, where following signalization, certain turning movements can be made more safety. t. King County Road Engineer reviewed and granted road variance approval on 6/20/2006 for Road Variance L06V0042 the variance approved approval was for stopping sight distance for the sag curve and required Hlumlnation to Improve visibility. Threshold Determination The responsible official finds that the above described proposal does not pose a probable · significant adverse impact to the environment, provided the mitigation measures listed below are applied as conditions of permit Issuance. This finding Is made pursuant to RCW 43.21 c, KCC 20.44 and WAC 197-11 after reviewing the environmental checklist and other information on file with the lead agency and considering mitigation measures which the agency or the applicant will Implement as part of the proposal. The responsible official finds this Information reasonably sufficient to evaluate the environmental impact of this proposal. Mitigation List The followlng mitigation measures shall be at.teched as conditions of permit issuance. These mitigation measures are consistent with policies, plans, rules, or regulations designated by KCC 20.44.080 as a basis for the exercise of substantive authority and in effect when this threshold determination Is Issued. Key sources of substantive authority for each mitigation measure are in parentheses; however, other sources of substantive authority may exist but are not expressly listed. L03P0018 / REVISED SEPA TD December 29, 2006 Page 3 1. To mitigate the significant adverse impact the plat of Rosemonte will have on the intersections of SR 900/148 1 h Ave SE and SR 900/164 1h Ave SE, the applicant shall install, either individually or in conjunction with other development projects in this area, the following improvements at the SR 900/148 1h Ave intersection: • A traffic signal, and • Eastbound and westbound left turn lanes The design for the SR 900/148" Ave Intersection improvements shall be approved by the Washington State Department of Transportation (and by King County to the extent such improvements are located in County right-of-way). In addition, at a minimum, the existing entering sight distance looking east for the north and south legs of the Intersection (602 feet and 388 feet, respectively) shall not be reduced as part of the Intersection Improvements. Documentation shall be submitted to show this requirement Is met. All construction work associated with the intersection Improvements shall be completed between April 1" and September 30". This seasonal restriction shall be clearly shown on the final engineering plans. In lieu of the Installation of the above-noted intersection Improvements prior to final plat approval, the applicant may post a financial guarantee with WSDOT which assures the Installation of these improvements within two years of the recording of Rosemonte. In this event, Intersection improvement design must be approved by WSDOT prior to King County approval of the engineering plans for Rosemonte. If the above-noted intersection improvements have already been made by others prior to the recording of Rosemonte, or a financial guarantee has been posted by others which assures the installation of these improvements, then the applicant for Rosemonte shall pay a pro-rata share dollar amount to the developer who has made the improvements or "bonded" for the improvements, In an amount proportional to the impacts of Rosemonte. The pro-rata share dollar amount to be paid shall be set by WSDOT, and documentation shall be provided by the Rosemonte applicant to the King County Land Use Services Division to show this payment has been made, prior to final plat recording. The pro-rata dollar amount to be paid shall be based on the following: • The final Rosemonte lot count • The trip distribution for Rosemonte • The total trips contributed to the intersection of SR 900.148" Ave by the plats of Aster Park (LOOP0024), Stone Ridge 9L99P3008), East Renton (L02P0005), Shamrock (L02P0014), Rosemonte (aka Ironwood-L03P0018), Martin (L05P0019) and any future land use applications submitted to King County for which compliance with the King County Intersection Standards (KCC 14.80) is required at either the SR 900/1481h Ave intersection, or the SR 900/164" Ave High Accident Location. In. the event that either King County or WSDOT adopts a formal 'latecomer's" system prior to final plat recording, that system may be followed in lieu of the approach described above, at the discretion of the applicant, as long as at a minimum there is a financial guarantee which assures the above-noted intersection improvements will be installed within two years of the date of recording of the plat of Rosemonte. [Comprehensive Plan Policy T-303 and King County Code 21A.28.060A] . L03P0018 / REVISED SEPA TD December 29, 2006 Page4 2. Documentation shall be provided to demonstrate to the satisfaction of WSDOT that stopping sight distance (360 feet) Is available on the east leg of the SR 900/1481h Ave intersection. The intersection shall be modified by the applicant, if necessary, so that this stopping sight distance requirement is met on the east leg. In addition, the applicant shall clear vegetation within the right-of-way along SR 900, east of 148th Ave., to maximize the entering sight distance for the north and south legs of the Intersection. [Comprehensive Plan Policy T-303 and King County Comprehensive Policy T-303 and King County Code 21A.28.060A] Extilnded Period for Comments and Appeals The SEPA determination may be appealed in writing to the King County Hearing Examiner. Written comments or a notice of appeal must be filed with the Department of Development and Environmental Services (DOES) at the address listed below prior to 4:30 p.m. on January 22, 2007 be accompanied with a filing fee of $250.00 payable to the King County Office of Finance .. Please reference the file numbers when corresponding. · If a SEPA Appeal Is filed, the appellant must also file a Statement of Appeal with ODES at the address listed below prior to 4:30 p.m. on January 22, 2007. The Statement of Appeal shall identify the decision appealed (Including the file number) and the alleged errors in that SEPA decision. The Statement of Appeal shall state: 1) specific reasons why the decision should be reversed or modified; and 2) the harm suffered or anticipated by the appeHant, and ttie relief sought. The scope of an appeal shall be based on matters or issues raised in the Statement of Appeal. Failure to timely file a Notice of Appeal, appeal fee or Statement of Appeal, deprives the Hearing Examiner of jurisdiction to consider the appeal. Comment/appeal deadline: Appeal flllng fee: Address for comment/appeal: 4:30 PM on January 22, 2007 $250 check or money order made out to the King County Office of Finance King County Land Use Services Division 900 Oakesdale Avenue SW Renton, WA 98057-5212 ATTN: Current Planning Section December 29, 2006 Date Signed ' ' 11, 1" J I <:r\. OFFICE OF THE HEARING EXAMINER KING COUNTY, WASHINGTON 400 Yesler Way, Room 404 Seattle, Washington 98104 Telephone (206) 296-4660 Facsimile (206) 296-1654 Email: hearex@metrokc.gov April 5, 2007 REPORT AND DECISION SUBJECT: Department of Development and Environmental Services File No. L02P0005 Proposed Ordinance no. 2007-0010 EAST RENTON Preliminary Plat Application Location: West of 148th Avenue Southeast at approximately Southeast 120th Street, Renton Applicant: CamWest Real Estate Dev., Inc. represented by Robert Johns, Attorney Johns Monroe Mitsunaga 1601 -I 14th Ave. SE,# 110 Bellevue, Washington 98004 Telephone: (425) 467-9960 Facsimile: (425) 451-2818 King County: Department of Development and Environmental Services (ODES) represented by Karen Scharer 900 Oakesdale Avenue Southwest Renton, Washington 98055-1219 Telephone: (206) 296-7114 Facsimile: (206) 296-7051 SUMMARY OF RECOMMENDATIONS/DECISION: Department's Preliminary Recommendation: Department's Final Recommendation: Examiner's Decision: EXAMINER PROCEEDINGS: Hearing Opened: Continued for Administrative Purposes: Hearing Closed: Approve subject to conditions Approve subject to conditions (modified) Approve subject to conditions (modified) March 22, 2007 March22, 20<17:,@ MrtfcH~3, 2007~. D DEC Z 6 ;:no? [_ 0 7 \/.<Or/.@.~. L02P0005-East Renton 2 The public hearing on the proposed subdivision of East Renton was conducted concurrently with the public hearing on the proposed subdivision ofRosemonte (DOES File No. L03P0018). Participants at the public hearing and the exhibits offered and entered are listed in the attached minutes. At 12:31 p.m. the hearing was continued for administrative purposes, to allow for the submission of proposed exh. no. 29, that would set forth the final recommendation of the department concerning revisions to recommended conditions #'s 6, 20, 21 and 22. Exhibit 29 was received by the Hearing Examiner on March 22, 2007, and the hearing was declared closed on March 23, 2007 A verbatim recording of the hearing is available in the office of the King County Hearing Examiner. ISSUES AND TOPICS ADDRESSED: • Future development tract Red-tailed hawks nest Safe walking conditions SUMMARY: • • • Recreation area Wetland buffers Surface water drainage The proposed subdivision of 17.01 acres into 66 lots in the urban area is approved subject to conditions. FINDINGS, CONCLUSIONS & DECISION: Having reviewed the record in this matter, the Examiner now makes and enters the following: FINDINGS: 1. General Information: Developer: Engineer: STR: Location: Zoning: Acreage: Number of Lots: Density: Lot Size: Camwest Real Estate Development, Inc. 9720 NE !20th Place, Suite 100 Kirkland, WA 98034 Contact: Sars Slatten 425-825-1955 Triad Associates 12112 115th Ave NE Kirkland, WA 98034 Contact: Gerry Buck 425-821-8448 10-23-05 West of 148"' Ave SE at approximately SE 120th St. Parcel -1023059023 R-4 17.01 acres 66 Approximately 3.9 units per acre Approximately 5,000 square feet in size ,;J' ' ' L02P0005-East Renton Proposed Use: Sewage Disposal: Water Supply: Fire District: School District: Single Family Detached Dwellings City of Renton Water District # 90 City of Renton Issaquah School District Complete Application Date: April 17, 2002 3 2. Except as modified herein, the facts set forth in the King County Land Use Services Division's preliminary report to the King County Hearing Examiner for the March 22, 2007, public hearing are found to be correct and are incorporated herein by this reference. The LUSD staff recommends approval of this subdivision; subject to conditions. 3. Development of this subdivision may affect, and lead to the abandonment of, a red-tailed hawks nest on the subject property. The red-trail hawk is not an endangered or threatened species, and no protection of the red-tail hawk is afforded by law or the King County Code within the designated urban area of King County. 4. The applicant has proposed the establishment of Tract E as a "future development" tract. DOES determined that there is no reasonable access available to Tract E that would not cross wetland or wetland buffer. At the hearing the applicant abandoned its request to designate Tract E as a "future development" tract, and proposes to establish that tract as recreation area, to be connected by trail with the designated recreation/detention Tract G within this subdivision and adjacent to the proposed plat ofRosemonte. 5. The applicant has submitted a revised recreation plan for this subdivision and the adjacent plat of Rosemonte ( exh. 26). This plan provides adequate area within Tracts C, G and E and within the proposed recreation tract and trail within Rosemonte to serve these plats jointly with well conceived amenities for recreation and open space, consistent with the requirements of the King County Code. To the extent that a portion of the recreation area necessary to meet the requirements for the plat of Rosemonte is located on the East Renton property, that can be corrected by boundary line adjustment or recording the two plats as a single plat, ifDDES determines that it is necessary to do so. 6. Wetland buffers within this subdivision will need to be modified, utilizing the buffer averaging provisions of the critical areas code, to accommodate the proposed alignment of 145th Avenue Southeast in the vicinity of the north property line, and adding buffer to mitigate the impacts of the proposed trail corridor within Tract F (between Tracts E and G), in accordance with the provisions ofKCC 21A.24.045.D.47.b. 7. The proposed subdivision will provide for safe walking conditions for students who will walk to Apollo Elementary School on southeast I 17th Street by constructing urban improvements to 148th Avenue Southeast from the plat to Southeast I 17th Street. A school crosswalk ( crossing 148th Avenue Southeast) is located on the north side of Southeast I 17th Street, where an existing walkway is used by students to travel along the north side of Southeast I 17th Street east from 148th Avenue Southeast to the school. This crosswalk also serves students walking from the area north of Southeast I 17th Street. Consequently, the crosswalk should be maintained on the L02P0005-East Renton 4 north side of Southeast I 17th Street unless it is physically impractical to do so because of constraints resulting from the topography within the right-of-way for 148th Avenue Southeast, south of Southeast I 17th Street. If those constraints preclude extending curb, gutter and sidewalk from the plat of East Renton to the north side of Southeast I 17th Street, the crosswalk can be relocated to the south, and improvements made on the east side of 148th Avenue Southeast to Southeast I 17th Street. 8. The conceptual review of drainage plans has shown that there are no downstream impacts likely to occur from development of the subject property if Level I flow control and basic water quality treatment improvements are designed and constructed in a.ccordance with the 1998 King County Drainage Manual. The fmal drainage plan will include calculations to assure that the capacity of drainage facilities and discharge rates will be consistent with those flow control standards. CONCLUSIONS: I. If approved subject to the conditions recommended below, the proposed subdivision will comply with the goals and objectives of the King County Comprehensive Plan, subdivision and zoning codes, and other official land use controls and policies of King County. 2. If approved subject to the conditions recommended below, this proposed subdivision will make appropriate provision for the public health, safety and general welfare, and for open spaces, drainage ways, streets, other public ways, transit stops, potable water supply, sanitary waste, parks and recreation, playgrounds, schools and school grounds and safe walking conditions for students who only walk to school; and it will serve the public use and interest. 3. The conditions for fmal plat approval recommended below are in the public interest and are reasonable and proportionate requirements necessary to mitigate the impacts of the development upon the environment. 4. The dedications ofland or easements within and adjacent to the proposed plat, as required for final plat approval or as shown on the proposed preliminary plat submitted by the Applicant on March 17, 2006 and the conceptual recreation plan submitted March 22, 2007 (exh. 26), are reasonable and necessary as a direct result of the development of this proposed plat, and are proportionate to the impacts of the development. 5. No provisions are required to be made by this subdivision for the protection of the red-tail hawks nest(s) on the site. 6. The proposed future development designation for Tract E has been withdrawn by the applicant, and that tract shall be a portion of the designated recreation area for the current development. 7. The proposed conceptual recreation plan submitted as exh. no. 26 is a reasonable and appropriate plan to serve the plats of East Renton and Rosemonte jointly. Minor alterations may be made in the final design and review by DDES, and boundary adjustments, if necessary, may be made to comply with provisions ofKCC 21A.14.180-200. L02P0005-East Renton 5 8. Revisions to the wetland buffers will be necessary to comply with the provisions of the King County Critical Areas Code, to permit construction of 145th Avenue Southeast in the vicinity of the north property line and to mitigate the impacts of the trail connecting Tracts E and G. 9. In order to provide for safe walking conditions for students walking from this development to Apollo Elementary School, urban improvements must be made to 148th Avenue Southeast north from the proposed plat to the north side of Southeast I 17th Street. These improvements should be made to the west side of 148th Avenue Southeast to the extent it is feasible to do so. In the event it is not practical to construct improvements extending to the existing crosswalk located at the north side of Southeast I 17th Street, a crosswalk may be established south of Southeast I 17th Street and a safe walkway provided on the east side of 148th Avenue Southeast from the new crosswalk to the north side of Southeast I 17th Street .. 10. Calculations for surface water detention facilities shall assure that the release of storm water from the site does not exceed the rates allowed by the 1998 King County Drainage Manual for achieving Level I flow control. DECISION: The pr_oposed preliminary plat of East Renton, as revised and received on March 17, 2006, is approved, subject to the following conditions of final plat approval: I. . Compliance with all platting provisions of Title 19A of the King County Code. 2. All persons having an ownership interest in the subject property shall sign on the face of the final plat a dedication that includes the language set forth in King County Council Motion No. 5952. 3. The plat shall comply with the base density and minimum density requirements of the R-4 zone classification. All lots shall meet the minimum dimensional requirements of the R-4 zone classification or shall be as shown on the face of the approved preliminary plat, whichever is larger, except that minor revisions to the plat which do not result in substantial changes may be approved at the discretion of the Department of Development and Environment Services. Any/all plat boundary discrepancy(ies) shall be resolved to the satisfaction ofDDES prior to the submittal of the final plat documents. As used in this condition, "discrepancy" is a boundary hiatus, an overlapping boundary or a physical appurtenance which indicates an encroachment, lines of possession or a conflict of title. 4. The applicant must obtain final approval from the King County Health Department. 5. All construction and upgrading of public and private roads shall be done in accordance with the King County Road Standards established and adopted by Ordinance No. 11187, as amended (1993 KCRS). (Also see conditions 8 and 24.) L02P0005-East Renton 6. The applicant must obtain the approval of the King County Fire Protection Engineer for the adequacy of the fire hydrant, water main, and fire flow standards of Chapter 17 .08 of the King County Code. 6 All future residences constructed within this subdivision are required to be sprinklered (NFP A 13D) unless the requirement is removed by the King County fire Marshal or his/her designee. The Fire Code .requires all portions of the exterior walls of structures to be within 150 feet (as a person would walk via an approved route around the building) from a minimum 20-foot wide, unobstructed driving surface. To qualify for removal of the sprinkler requirement, driving surfaces between curbs must be a minimum of 28 feet in width when parking is allowed on one side of the roadway, and at least 36 feet in width when parking is permitted on both sides. The road width requirement applies to both on-site access and roads accessing the subdivision. 7. Final plat approval shall require full compliance with the drainage provisions set forth in King County Code 9.04. Compliance may result in reducing the number and/or location oflots as shown on the preliminary approved plat. Preliminary review has identified the following conditions of approval, which represent portions of the drainage requirements. All other applicable requirements in KCC 9.04 and the Surface Water Design Manual (SWDM) must also be satisfied during engineering and final review. a. Drainage plans and analysis shall comply with the 1998 King County Surface Water Design Manual. DOES approval of the drainage and roadway plans is required prior to any construction. b. Current standard plan notes and ESC notes, as established by DOES Engineering Review shall be shown on the engineering plans. c. The following note shall be shown on the final recorded plat: "All building downspouts, footing drains, and drains from all impervious surfaces such as patios and driveways shall be connected to the permanent storm drain outlet as shown on the approved construction drawings # on file with DOES and/or the Department of Transportation. This plan shall be submitted with the application of any building permit. All connections of the drains must be constructed and approved prior to the final building inspection approval. For those lots that are designated for individual lot infiltration systems, the systems shall be constructed at the time of the building permit and shall comply with the plans on file." d. Storm water facilities shall be designed using the KCRTS level one flow control standard. Water quality facilities shall also be provided ·using the basic water quality protection menu. The size of the proposed drainage tracts may have to increase to accommodate the required detention volumes and water quality facilities. All runoff control facilities shall be located in a separate tract and dedicated to King County unless portions of the drainage tract are used for recreation space in accordance with KCC 21A.14.180. L02P0005-East Renton 7 e. The applicant has received approval for two drainage adjustment applications regarding designs for the discharge of storm water and a shared facility detention pond. The adjustment decisions are contained within file numbers L02V0089 and L04VO 103. During final review of the engineering plans, all applicable conditions of the adjustment approvals shall be satisfied including requirements for the shared facility located offsite within the plat of Rosemonte. f. As stated in the drainage adjustment decision, the offsite drainage pond shall be designed using the Level 1 flow control standard. Basic water quality standards are also required for design of the facility. If a wet pond facility is provided for water quality, the design shall comply with the 3:1 flow length ratio as outlined on page 6-72 in the drainage manual. For evaluation of the onsite storm vault and the off site detention 'pond, a soils report shall be prepared by a geotechnical engineer to evaluate the soils and groundwater conditions. g. For any proposed bypass of storm water from the flow control facility, the final drainage designs shall comply with applicable design requirements in the drainage manual as outlined on pages 1-36 and 3-52. h. As required by Special Requirement No. 2 in the drainage manual, the 100-year floodplain boundaries for the onsite wetlands shall be shown on the final engineering plans and recorded plat. Access and Roads 8. The proposed subdivision shall comply with the 1993 King County Road Standards (KCRS) including the following requirements: a. During preliminary review the applicant submitted a road variance application (File No. L03V0049), regarding the crest vertical curve and substandard stopping sight distance along the plat frontage. In response to the variance application, the King County Road Engineer provided a decision letter dated October 20, 2004 which approved the variance based upon specific design criteria for constructing 148th Ave SE. As noted in the variance decision, the crest curve on 148th Ave SE must be reconstructed to provide 455 feet of stopping sight distance based upon design criteria with a 2-foot target. The final road improvements and design plans for the project shall demonstrate compliance with all applicable conditions of approval as stated in the variance decision. b. 148th Avenue SE shall be improved along the frontage as an urban collector arterial including all design criteria from the road variance decision. In accordance with KCRS 2.02, the curb location shall be designed at 22-feet from the road crown to provide full width travel lanes and a bike lane. The preliminary design plans for East Renton shows road grading extending outside the right-of-way on the east side of 148th Ave SE. During final engineering review, the applicant shall acquire easements for any proposed construction on private property or provide an alternative design which is acceptable to King County for road construction within the existing right-of-way. L02P0005-East Renton 8 c. The project entry road to 1481h Ave SE shall be improved as an urban neighborhood .collector. As shown on the preliminary plat, the required right-of-way width is 56 feet. d. The proposed roads within the subdivision shall be improved using urban design standards and in accordance with the street classifications shown on the preliminary plat map. e. Tract D shall be improved as a private joint use driveway serving a maximum of two lots. The lots served shall have undivided ownership of the tract and be responsible for its maintenance. As specified in KCRS 3.0IC, improvements shall include an 18 foot paved surface and a minimum tract width of 20 feet. Drainage control shall include a curb or thickened edge on one side. f. Street trees shall be included in the design of all road improvements and shall comply with Section 5.03 of the KCRS. g. Street illumination shall be provided along the plat frontage and at intersections with arterials in accordance with KCRS 5.05. h. The proposed road improvements shall address the requirements for road surfacing outlined in KCRS Chapter 4. As noted in section 4.0 IF, full width pavement overlay is required where widening existing asphalt, unless otherwise approved by King County. 1. 1481h Ave SE is classified as an arterial street which may require designs for bus zones and turn outs. As specified in KCRS 2.16, the designer shall contact Metro and the local school district to determine specific requirements. j. Modifications to the above road conditions may be considered by King County pursuant to the variance procedures in KCRS 1.08. 9. All utilities within proposed rights-of-way must be included within a franchise approved by the King County Council prior to final plat recording. 10. The site plans for East Renton show the northerly road stub for 1451h Ave SE which may extend into the wetland buffer and associated setback within the Rosemont plat. During engineering review for East Renton, a revised road alignment and grading plan shall be provided which demonstrates that road construction within Rosemonte will comply with applicable sensitive area codes. The revised road design and grading plan may result in modification or loss of lots as shown on the preliminary plat. Alternatively, the applicant may seek approval to use buffer averaging as a means to revise the location of the buffer and BSLB to achieve code compliance within Rosemonte. 11. There shall be no direct vehicular access to or from 1481h Ave SE from those lots which abut it. A note to this effect shall appear on the engineering plans and the final plat. 12. The applicant shall provide a safe walking access to Apollo Elementary School with urban improvements along the west side of 148th Ave NE to the existing crosswalk on the north side of .. L02P0005-East Renton 9 SE I I 711, St. This improvement includes urban frontage improvements along property frontage of the Plat of East Renton, urban improvements along frontage of Rosemonte and urban improvements north to the existing crosswalk on the north side of SE I I 711, ST. (It is noted that the adjoining plat of Rosemonte also will be subject to urban frontage requirements and urban improvements north to the existing crosswalk on the north side of SE I J.711, ST.) In the event it is not practical to construct urban improvements on the west side of 148th Avenue Southeast extending to the existing crosswalk, a new crosswalk may be established south of Southeast I I 7th Street and a safe walkway provided on the east side of 148th Avenue Southeast from the new crosswalk to the north side of Southeast I 17th Street. This alternative may use a graded surface on the east side of 148th Ave SE to ensure that school-age pedestrians are provided an acceptable-width walkway surface behind the curbing. The walkway shall be designed to the satisfaction of the school district and DDES. Mitigation/Impact Fees 13. The applicant or subsequent owner shall comply with King County Code 14.75, Mitigation Payment System (MPS), by paying the required MPS fee and administration fee as determined by .. the applicable fee ordinance. The applicant has the option to either: (I) pay the MPS fee at the .final plat recording, or (2) pay the MPS fee at the time of building permit issuance. If the first option is chosen, the fee paid shall be the fee in effect at the time of plat application and a note shall be placed on the face of the plat that reads, "All fees required by King County Code 14.75, . Mitigation Payment System (MPS), have been paid." If the second option is chosen, the fee paid shall be the amount in effect as of the date of building permit application. 14. Lots within this subdivision are subject to King County Code 21A.43, which imposes impact fees to fund school system improvements needed to serve new development. As a condition of final approval, fifty percent (50%) of the impact fees due for the plat shall be assessed and collected immediately prior to the recording, using the fee schedules in effect when the plat receives final approval. The balance of the assessed fee shall be allocated evenly to the dwelling units in the plat and shall be collected prior to building permit issuance. Wetlands 15. Preliminary plat review has identified specific requirements which apply to this project as listed below. All other applicable requirements from K.C.C. 21A.24 shall also be addressed by the applicant. a. The Class 2 wetland shall have a minimum SO-foot buffer of undisturbed vegetation as measured from the wetland edge. b. Sensitive area tract(s) shall be used to delineate and protect sensitive areas and buffers in development proposals for subdivisions and shall be recorded on all documents of title of record for all affected lots. L02P0005-East Renton 10 c. Buffer width averaging may be allowed by King County if it will provide additional protection to the wetland/stream or enhance their functions, as Jong as the total area contained in the buffer on the development proposal site does not decrease. In no area shall the buffer be less than 65 percent of the required minimum distance. To ensure such functions are enhanced a mitigation plan will be required for the remaining on-site sensitive areas. An enhancement plan shall be submitted for review during engineering review. d. A 15-foot BSBL shall be established from the edge of buffer and/or the sensitive areas Tract( s) and shown on an affected lots. e. To ensure long term protection of the Sensitive Areas a split-railed fence of no more than 4 feet in height shall be installed along the Sensitive Area Tract boundaries in the area of proposed lots. Sensitive Area signs shall be attached to the fence at no less than I 00 foot intervals. f. If alterations of streams and/or wetlands are approved in conformance with K.C.C. 21A.24, then a detailed plan to mitigate for impacts from that alteration win be required to be reviewed and approved along with the plat engineering plans. A performance bond or other financial guarantee will be required at the time of plan approval to guarantee that the mitigation measures are installed according to the plan. Once the mitigation work is completed to a ODES Senior Ecologist's satisfaction, the performance bond may be replaced by a maintenance bond for the remainder of the five-year monitoring period to guarantee the success of the mitigation. The applicant shan be responsible for the installation, maintenance and monitoring of any approved mitigation. The mitigation plan must be installed prior to final inspection of the plat. g, Prior to commencing construction activities on the site, the applicant shall temporarily mark sensitive areas tract(s) in a highly visible manner, and these areas must remain so marked until all development proposal activities in the vicinity of the sensitive areas are completed. h. During engineering plan review the applicant shall provide a wetland hydrology analysis to demonstrate how the wetland hydrology will be maintained post-construction. i. Detention out-fan structures maybe permitted within the wetland/stream buffers, however, structures shall be located in the outer edge of the buffer, if possible. An buffer impacts shall be mitigated. 16. Development authorized by this approval may require other state and/or federal permits or approvals. It is the applicant's responsibility to correspond with these agencies prior to beginning work on the site. 17. During engineering review, the plan set shall be routed to the sensitive areas group to determine if the above conditions have been met. L02P0005-East Renton 11 Geo technical 18. The applicant shall delineate all on-site erosion hazard areas on the final engineering plans ( erosion hazard areas are defined in KCC 21 A.06.415). The delineation of such areas shall be approved by a DDES geologist. The requirements found in KCC 21 A.24.220 concerning erosion hazard areas shaJI be met, including seasonal restrictions on clearing and grading activities. Sensitive Area 19. The following note shall be shown on the final engineering plan and recorded plat: Other RESTRICTIONS FOR SENSITNE AREA TRACTS AND SENSITNE AREAS AND BUFFERS Dedication of a sensitive area tract/sensitive area and buffer conveys to the public a beneficial interest in the land within the tract/sensitive area and buffer. This interest includes the preservation of native vegetation for all purposes that benefit the public health, safety and welfare, including control of surface water and erosion, maintenance of slope stability, and protection of plant and animal habitat. The sensitive area tract/sensitive area and buffer imposes . upon all present and future owners and occupiers of the land subject to the tract/sensitive area and buffer the obligation, enforceable on behalf of the public by King County, to leave undisturbed all trees and other vegetation within the tract/sensitive area and buffer. The vegetation within the tract/sensitive area and buffer may not be cut, pruned, covered by fill, removed or damaged without approval in writing from the King County Department of Development and Environmental Services or its successor agency, unless otherwise provided by law. The common boundary between the tract/sensitive area and buffer and the area of development activity must be marked or otherwise flagged to the satisfaction of King County prior to any clearing, grading, building construction or other development activity on a Jot subject to the sensitive area tract/sensitive area and buffer. The required marking or flagging shall remain in place until all development proposal activities in the vicinity of the sensitive area are completed. No building foundations are allowed beyond the required 15-foot building setback line, unless otherwise provided by law. 20. The plat design shall be revised to provide the minimum suitable recreation space consistent with the requirements ofK.C.C. 21A.14.180 and K.C.C. 21A. 14.190 (i.e., minimum area, as well as, sport court[s), children's play equipment, picnic table[s], benches, etc.), as shown on hearing exh. no. 26. a. A detailed recreation space plan (i.e., location, area calculations, dimensions, landscape specs, equipment specs, etc.) shall be submitted for review and approval by DDES prior to or concurrent with the submittal of engineering plats. L02P0005-East Renton b. A performance bond for recreation space improvements shall be posted prior to recording of the plat. 12 21. Tract E shall be designated for recreational area, with an approved trail (across wetland buffers) extending from the recreational Tract G and functioning as an extension of recreation from Tract G. Plans for the tract -designation and design, shall comply with codes and shall be to the satisfaction ofDDES prior to engineering approval. 22. A homeowners' association or other workable organization shall be established to the satisfaction ofDDES which provides for the ownership and continued maintenance of the recreation, open space and/or sensitive area tract(s) which combines usage ofrecreation area within L03POOl 8, the plat ofRosemonte, pursuant to hearing exh. no. 26. (See condition no. 25.) 23. Street trees shall be provided as follows (per KCRS 5.03 and K.C.C. 21A.16.050): a. Trees shall be planted at a rate of one tree for every 40 feet of frontage along all roads. Spacing may be modified to accommodate sight distance requirements for driveways and intersections. b. Trees shall be located within the street right-of-way and planted in accordance with Drawing No. 5-009 of the 1993 King County Road Standards, unless King County Department of Transportation determines that trees should not be located in the street right-of-way. c. If King County determines that the required street trees should not be located within the right-of-way, they shall be located no more than 20 feet from the street right-of-way line. d. , The trees shall be owned and maintained by the abutting lot owners or the homeowners association or other workable organization unless the county has adopted a maintenance program. Ownership and maintenance shall be noted on the face of the final recorded plat. e. The species of trees shall be approved by DOES iflocated within the right-of-way, and shall not include poplar, cottonwood, soft maples, gum, any fruit-bearing trees, or any other tree or shrub whose roots are likely to obstruct sanitary or storm sewers, or that is not compatible with overhead utility lines. f. The applicant shall submit a street tree plan and bond quantity sheet for review and approval by DOES prior to engineering plan approval. g. The applicant shall contact Metro Service Planning at (206) 684-1622 to determine if 148th Ave SE is on a bus route. If 148th Ave SE is a bus route, the street tree plan shall also be reviewed by Metro. h. The street trees must be installed and inspected, or a performance bond posted prior to recording of the plat. If a performance bond is posted, the street trees must be installed and inspected within one year of recording of the plat. At the time of inspection, if the L02P0005-East Renton 13 SEPA trees are found to be installed per the approved plan, a maintenance bond must be submitted or the performance bond replaced with a maintenance bond, and held for one year. After one year, the maintenance bond may be released after ODES has completed a second inspection and determined that the trees have been kept healthy and thriving. 1. A landscape inspection fee shall also be submitted prior to plat recording. The inspection fee is subject to change based on the current county fees. 24. The following have been established by SEPA as necessary requirements to mitigate the adverse environmental impacts of this development. The applicants shall demonstrate compliance with these items prior to final approval. (!.) To mitigate the significant adverse impact the plat of East Renton will have on the intersections of SR 9001148th Ave SE and SR 9001164th Ave SE, the applicant shall install, either individually or in conjunction with other development projects in this area, the following improvements at the SR 9001148th Ave intersection: • A traffic signal, and • Eastbound and westbound left turn lanes The design for the SR 9001148th Ave intersection improvements shall be approved by the Washington State Department of Transportation (and by King County to the extent such improvements are located in County right-of-way). ht addition, at a minimum, the existing · entering sight distance looking east for the north and south legs of the intersection (602 feet and :·386 feet, respectively) shall not be reduced as part of the intersection improvements. Documentation shall be submitted to show this requirement is met All construction work associated with the intersection improvements shall be completed between April l" and September 30th. This seasonal restriction shall be clearly shown on the final engineering plans. ht lieu of the installation of the above-noted intersection improvements prior to final plat approval, the applicant may post a financial guarantee with WSDOT which assures the . installation of these improvements within two years of the recording of East Renton. ht this event, intersection improvement design must be approved by WSDOT prior to King County approval of the engineering plans for East Renton. If the above-noted intersection improvements have already been made by others prior to the recording of East Renton, or a financial guarantee has been posted by others which assures the installation of these improvements, then the applicant for East Renton shall pay a pro-rata share dollar amount to the developer who has made the improvements or "bonded" for the improvements, in an amount proportional to the impacts of East Renton. The pro-rata share dollar amount to be paid shall be set by WSDOT, and documentation shall be provided by the East Renton applicant to the King County Land Use Services Division to show this payment has been made, prior to final plat recording. The pro-rata dollar amount to be paid shall be based on the following: • The final East Renton lot count • The trip distribution for East Renton L02P0005-East Renton 14 • The total trips contributed to the intersection of SR 900.1481h Ave by the plats of Aster Park (LOOP0024), Stone Ridge 9L99P3008), East Renton (L02P0005), Shamrock (L02P0014), Rosemonte (aka Ironwood-L03POOl8), Martin (L05POOl9) and any future land use applications submitted to King County for which compliance with the Kin} County Intersection Standards (KCC 14.80) is required at either the SR 900/148 Ave intersection, or the SR 9001164th Ave High Accident Location. In the event that either King County or WSDOT adopts a formal "latecomer's" system prior to final plat recording, that system may be followed in lieu of the approach described above, at the discretion of the applicant, as long as at a minimum there is a financial guarantee which assures the above-noted intersection improvements will be installed within two years of the date of · recording of the plat of East Renton. [Comprehensive Plan Policy T-303 and King County Code 21A.28.060A] (2.) Documentation shall be provided to demonstrate to the satisfaction ofWSDOT that stopping sight distance (360 feet) is available on the east leg of the SR 900/1481h Ave intersection. The intersection shall be modified by the applicant, if necessary, so that this stopping sight distance requirement is met on the east leg. In addition, the applicant shall clear vegetation within the right-of-way along SR 900, east of 148th Ave., to maximize the entering sight distance for the north and south legs of the intersection. [Comprehensive Plan Policy T -303 and King County Comprehensive Policy T -303 and King County Code 21A.28.060AJ 25. The recreation area may serve the adjacent plat ofRosemonte. If necessary, boundary line adjustments may be approved to establish a portion of the East Renton plat recreation area as a part of the Rosemonte Plat, or the two plats may be recorded as a single plat. 26. Wetland buffer averaging or additional buffer are required to compensate for reduction of wetland buffers adjacent to 145th Avenue southeast, as proposed in the vicinity of the north property line, and to compensate for construction of the recreation tract trail through wetland buffer between Tracts E and G. · ORDERED this 5th day of April, 2007. TRANSMITTED this 5th day of April, 2007, to the parties and interested persons ofrecord: Robert L. Anderson PO Box 353 Maple Valley WA 98038 Cam West Devel., Inc. Attn: Sara Slatten 9720 NE 120th Pl. #100 Kirkland WA 98034 Kristine & Keith Childs 12004 -148th Ave. SE Renton WA 98059 .. L02P0005-East Renton 15 Claudia Donnelly Renee & Mark Engbaum John Graves 10415 • 147th Ave. SE 5424 NE I 0th St. Lozier Homes Renton WA 98059 Renton WA 98059-4386 1203 I 14th Ave. SE Bellevue WA 98004 Ralph Hickman Robert D. Johns Rebecca Lind 9720 NE I 20th Pl. # I 00 Johns Monroe Mitsunaga City of Renton, EDNSP Kirkland WA 98034 1601 · I 14th Ave. SE,# 110 1055 S. Grady Way Bellevue WA 98004 Renton WA 98057 Seattle KC Health Dept. Triad Associates · Kim Claussen E. Dist. Environ. Health 12112 • I 15th Ave NE DDES/LUSD 14350 SE Eastgate Way Kirkland WA 98034 MS OAK-DE-0100 Bellevue WA 98007 Lisa Dinsmore Peter Dye Nick Gillen DDES/LUSD DDES/LUSD DDES/LUSD MS OAK-DE-0100 MS OAK-DE-0100 MS OAK-DE-0100 Shirley Goll Kristen Langley Karen Scharer DDES/LUSD DDES/LUSD DDES/LUSD MS OAK-DE-0100 MS OAK-DE-0100 MS OAK-DE-0100 Steve Townsend Larry West Kelly Whiting DDES/LUSD DDES/LUSD KC DOT, Rd. Srvcs. Div. MS OAK-DE-0100 MS OAK-DE-0100 MS KSC-TR-0231 Bruce Whittaker DDES/LUSD MS OAK-DE-0100 NOTICE OF RIGHT TO APPEAL ht order to appeal the decision of the Examiner, written notice of appeal must be filed with the Clerk of the King County Council with a fee of$250.00 (check payable to King County Office of Finance) on or before April 19, 2007. Ifa notice of appeal is filed, the original and six (6) copies ofa written appeal statement specifying the basis for the appeal and argument in support of the appeal must be filed with the Clerk of the King County Council on or before April 26, 2007. Appeal statements may refer only to facts contained in the hearing record; new facts may not be presented on appeal. Filing requires actual delivery to the Office of the Clerk of the Council, Room 1025, King County Courthouse, 516 3nl Avenue, Seattle, Washington 98104, prior to the close of business (4:30 p.m.) on the date due. Prior mailing is not sufficient if actual receipt by the Clerk does not occur within the applicable time period. The Examiner does not have authority to extend the time period unless the Office of the Clerk is not open on the specified closing date, in which event delivery prior to. the close of business on the next business day is sufficient to meet the filing requirement. L02P0005-East Renton 16 If a written notice of appeal and filing fee are not filed within fourteen ( 14) calendar days of the date of this report, or if a written appeal statement and argument are not filed within twenty-one (21) calendar days of the date of this report, the decision of the hearing examiner contained herein shall be the final decision of King County without the need for further action by the Council. MINUTES OF THE MARCH 22, 2007, PUBLIC HEARING ON DEPARTMENT OF DEVELOPMENT AND ENVIRONMENT AL SERVICES FILE NO. L02P0005 James N. O'Connor was the Hearing Examiner in this matter. Participating in the hearing were Karen Scharer, Pete Dye and Kristen Langley, representing the Department; Robert Johns representing the Applicant; and Renee Engbaum. Exhibit No. I Exhibit No. 2 Exhibit No. 3 Exhibit No. 4 Exhibit No. 5 Exhibit No. 6 Exhibit No. 7 Exhibit No. 8 Exhibit No. 9 Exhibit No. I 0 Exhibit No. 11 Exhibit No. 12 Exhibit No. 13 Exhibit No. 14 Exhibit No. 15 DOES file L02P0005 DOES preliminary report for L02P0005, prepared 12/29/2006 with attachments as follow: 2.1. Plat Map w/66 Lot Plat Design 2.2. City of Renton Sewer Availability 2.3. Road Variance/L03V0049 2.4. Surface Water Management Variance/L02V0089 2.5 Surface Water Management Variance/L04V0103 2.6. Density Calculations w/R-4 zoning 2.7 Recreation cross section for Tract G (previously labeled Tract C) Application for land use permit no. AOIP0071 received 4/3/2002 Environmental checklist received 4/3/2002 Revised SEPA Mitigated Determination ofNonsignificance, date ofrevised issuance: 12/29/2006 Affidavit of posting of Notice of Application indicating posting date of 5/3/2002, received by ODES on 5/3/2002 Revised Site plan (66 lot preliminary plat map) received 3/17/2006 Assessor's maps (2) SE 10-23-05 & SW 11-23-05 Revised Level I Downstream Analysis by Triad & Associates, received 11/24/2004 Traffic Impact Analysis by Gary Struthers Associates received 4/3/2002 Request for School Information form from the Issaquah School District, received 4/25/2002 King County Certificate of Water Availability, received 4/03/2002 Vicinity Map for LOSP0019, L03P0018 & L02P0005, prepared by KC staff on 3/19/2007 DOES Field Report and GIS Information dated 5/1/2002 Revised Wetlands Determination and Habitat analysis by C. Gary Schulz dated 9/12/2002 • • it' L02P0005-East Renton 17 ExhibitNo. 16 Exhibit No. 17 Exhibit No. 18 Exhibit No. 19 Exhibit No. 20 Exhibit No. 21 Exhibit No. 22 Exhibit No. 23 Exhibit No. 24 Exhibit No. 25 Exhibit No. 26 Exhibit No. 27 Exhibit No. 28 Exhibit No. 29 JNOC:gao L02POOOS RPT Watertype/stream Classification Survey comments from Washington Trout, dated 10/15/2004 Drainage outfall report by Associated Earth Sciences, Inc., dated 9/24/2002 Boundary line adjustment proposal with attached map, dated 5/3/2004 Not entered Response to East Renton Transportation Comments by Gary Struthers Associates, Inc., dated 1/23/2003 Washington State Department ofTranportation comments regarding Traffic Impact Analysis, dated I 1/13/2002 Letter from Claudia Donnelly dated 6/13/2003 regarding basin plan, with 2 attachments Note from Claudia Donnelly with attached copy of 11/12/03 newspaper article regarding transportation model City of Renton comments, regarding sewer service, dated 3/28/2002 Revised language for Condition 6 Conceptual recreation plan by Triad Associates Revised preliminary plat received March 22, 2007 Letter from Renee and Mark Engbaum dated March 22, 2007, with attached map indicating the location of their property Revisions to Conditions 20, 21 and 22 ,. ' . . ' ® King County DEPARiMENT OF DEVELOPMENT AND ENVIRONMENTAL SERVICES . LAND USE SERVICES DIVISION KING COUNTY, WASHINGTON PRELIMINARY REPORT TO THIE HEARING EXAMINER March 22, 2007 -PUBLIC HEARING AT 9:30 A.M. DOES Hearing Room 900 Oakesdale Avenue Southwest Renton, WA 98057-5212 Phone: (206) 296-6600 PROPOSED PLAT OF EAST RENTON FILE NO: L02P0005 PROPOSED ORDINANCE NO: 2007-0010 A. SUMMARY OF PROPOSED ACTION: This is a request for a subdivision of 17.01 acres into 66 lots for detached single- family dwellings. The proposed density Is 3.9 dwelling units per acre based on gross area. Density based on net bulldable area of 1.1.88 acres is 5.6 units per acre. The lot sizes are predominately 5,000 square feet. See Attachment 1 for a · copy of the proposed plat map. B. GENERAL INFORMATION: Developer. Engineer. STR: Location: Zoning:· Acreage: Number of Lots: Density: Lot Size: Proposed Use: · Sewage Disposal: Water Supply: Fire District: School District: Camwest Real Estate-Development, Inc. 9720 NE 120~ Place, Suite 1 _00 Kirkland, WA 98034. Contact: Sers Slatten 425-825-1955 Triad Associates 12112115'' Ave NE Kirkland, WA 98034 Contact: Gerry Buck 425-821-8448 10-23-05 West of 1481h Ave SE at approximately SE120~ St. Parcel -1023059023 . R-4 17.01 acres 66 Approximately 3.9 units per acre Approximately 5,000 square feet in size Single Family Detached Dwellings City of Renton Water District# 90 City of Renton Issaquah School District Complete Application Date: April 17, 2002 C. HISTORY/BACKGROUND: The Subdivision Technical Committee (STC) of Ki6g County has conducted an on- site examination of the subject property. The STC has discussed the proposed development with the applicant to clarify technical details of the application, and to determine the compatlblllty of this project with applicable King County plans, codes, and other ~fflclal documents regulating this development. As a result of preliminary discussions, the applicant presented the Technical Committee with numerous revision~ with the most recent plat revision on March 17, 2006. The modifications from the inttial submittal include: • · Revisod entrance to the plat , Revised location of recreational space , Clarification of t~e sidewalk improvements to be constructed along frontage and within the plat. • Adjustment to the buffer and BSBL lines associated with the on site wetlands. , Revised plat boundaries, eliminating the far wast portion (2+ acres) from the plat application. Boundary revision was completed under file L04L0055 and recorded under# 20041223900001. The purpose of the boundary adjustment was to separate that portion of the site annexed Into the City of Renton under Ordinance 5147, effective on July 6, 2005. • SWM Adjustment L02V0089 approved allowing the diversio~ of runoff to a single facility. • s·ubsequently SWM Adjustment L04V0103 was approved 3124105 for shared facility concept of the northeast comer of East Repton 1o utilize eastern drainage faclllty in Rosemonte. , Road Variance L03V0049 approved 10/20/2004 for a 620 -foot vertical curve with 455 feet of stopping sight distance, utilizing a two-foot target. Additionally approved is the slight grade break (under 1 %) at .the north end of the vertical curve. D. THRESHOLD DETERMINATION OF ENVIRONMENTAL SIGNIFICANCE: Pursuant to the State Environmental Polley Act (SEPA), RCW 43.21 C, the responsible official of LUSD Issued a mitigatod threshold determination of non- significance (MONS) for the proposed development on December 15, 2006. This detennlnatlon was based on the review of the environmental checklist and other pertinent documents, resulting in the conclusion that the proposal would not cause probable significant adverse Impacts on the environment proyjded mitigations measures are implemented. Subsequently, staff recognized Incorrect references to other subdivisions and Issued a REVISED MONS on December 29, 2006 referencing the following mitigations: 1. To mitigate the significant adverse impact the plat of East Renton will have on the intersections of SR 900/148 11' Ave SE and SR 900/1641h Ave SE, the applicant shall install, either individually or In conjunction with other development projects In this area, the following Improvements at the SR 900/1481" Ave intersection: • A traffic signal, and • Eastbound and westbound left tum lanes FILE NO L02P0005 Page 2 The. design for the SR 900/148~ Ave intersection improvements shall be approved by the Washington State Department of Transportation (and by King County to tho extent such improvements are located in County right-of- way). In addition, at a minimum, the existing entering sight distance looking east for the north and south legs of the intersection (602 feet and 386 feet, respectivGly) shall not be ·reduced as part of the intersection improvements. Documentation shall be submitted to show this requirement is met. All ' construction work associated with the intersection improvements shall be completed between April 1131 and September 30th. This seasonal restriction shall be clearly shown on the final engineering plans. In lieu of the installation of the abovo-noted intersection improvements prior to final plat approval, the applicant may post a financial guarantee with WSDOT which assures lhe msta!latlon of these improvements within two years of the recording of East Renton. In this event, intersection improvement design must be approved by WSDOT prior to King County approval of the.engineering plans for East Renton. If the above-noted intersection improvements have already been made by others prior to the. recording of East Renton, or a financial guarantee has been posted by olhera which assures the installation of these · Improvements, thon the applicant for East Renton shall pay a pro-rata share dollar amount to the developer who has made the improvements or "bonded" for the improvements, in an amount proportional to the impacts of East Renton. The pro-rata share dollar amount to be paid shall be set by WSDOT, and documentation shall be provided by the East Renton applicant to the King County Land Use Services Division to show this payment has been made, prior to final plat recording. The pro-rata dollar amount to be paid shall be based on the following: The final East Renton lot count • The trip distribution for East Renton • The total trips contributed to the intersection of SR 900.148'" Ave by the plats of Aster Park (LOOP0024), Stone Ridge 9L99P3008), East Renton (L02P0005), Shamrock (L02P0014), Rosemonte (aka Ironwood - L03P0018), Martin (L05P0019) and eny future land use applications submitted to King County for which compliance with the King County Intersection Standards (KCC 14.80) is requlreg at either the SR 9001148th Avo intersection, or the SR 900/164 Ave High Accident Location. · In the event that either King County or WSDOT adopts a fonnal "latecomer's" system prior to final plat recording, that system may bo followed in lieu of the approach described above, at the discretion of the applicant, as Jong as at a minimum there is a financial guarantee which assures the above-noted·intersectlon improvements w!ll be installed within. two years of the date of recording of tho plat of East Renton. [Comprehensive Plan Policy T-303 and King County Code 21A.28.060A) 2. Documentation shall be provided to demonstrate to the satisfaction of WSDOT that stop~ng sight distance (360 feet) is available on the east leg of the SR 900/148 Ave Intersection. The intersection shall be modified by the applicant. if necessary, so that this stopping sight distance requirement is met on the east leg. In addltion,.the app~cant shall clear vegetation within the right-of-way along SR 900, east of 1481 Ave., to maximize the entering sight distance for the north and south legs of the Intersection. [Comprehensive Plan Policy T-303 and King County Comprehensive Policy 'r-303 and King County Code 21A.28.060AJ An.environmental Impact statement (EIS) was not requirod as a result of issuing· the MONS. The appeal period for the revised threshold determination ends at the close of business on January 22, 2007. The specific mitigation measures have been incorporated as part of the applicant's proposal and are included in the list of ~ecommended conditions of preliminary approval. Agencies, affected Native American tribes and the public are offered the opportunity to comment on or appeal the determination until January 22, 2007. FILE NO L02P0005 Page 3 . ' E. AGENCIES CONTACTED: F. 1. King County Department of Natural Resources and Parks: Comments aro incorporated in the discussion in this report regarding wildlrre. 2. King County Fire Protection Engineer: Fire protection engineering preliminary approval has been granted subject to the standard code requirements and requirement for sprinklering of homos unless higher standards for road improvements are met. 3. Issaquah School District: The comments from this district have been Incorporated Into this report. 4. King County Water District #90: The comments from this district have been Incorporated into this report. 5. City of Renton (sewer provider): See Attachment 2. 6. METRO: No response. 7. Washington State Department of Ecology: No response. 8. Washington State Department of Fish and Wildlife: No res_ponse. 9. Washington State Department of Natural Resources: No Response 10. Washington State Department of Transportation: The comments from WSDOT have been incorporated into tho SEPA TD and in this report. NATURAL ENVIRONMENT: · 1. Topography: The site slopes from east down to the west with an overall elevation change of approximately 60 feet across the site with 20-30 percent slopes on the central 113rd of the site. 2. Soils: Two types of surfaces soils are found on this site per King County Soil Survey, 1973. a. The east 2/3rds of the site is classified as t,gQ -Alderwood gravely, sandy loam; 15-30% slopes. Runoff Is medium and the eroslo.n hazard Is severe. This soil has a severe !Imitation for foundaUons due to slope, and a moderate slippage potential. It has severe llmltatlons for septic tank filter fields due to very slow permeability In the substratum. b. The west 113'' of the site is. classttied as AqB -Alderwood gravely, sandy loam; 0-6% slopes. Runoff is slow and the erosion hazard is slight. This soil type has a moderate limitation for low building foundations due to a seasonally high water table, and severe limitations for septic tank filter fields due to very slow permeability in the substratum. Soll exploration was preformed by Associated Earth Sciences, Inc. in April of 2001 and Technical Memorandum, dated September 24, 2002 Indicates slopes 15 % or over are moderately susceptible to erosion, howeverthey·concluded is that with the design of the outfall the storm water flows will not be susceptible to erosion. 3. Wetland/streams: Awetland/and or stream report was prepared by C, Gary Schultz dated April 3, 2001 and revised September 12, 2002. The wetlands (A, B & C) are classified together as Class 2 Wetlands. These wetlands are part of a wetland system exceeding one acre in size and include forested area as the headwaters of Honey Creek. Some buffer averaging Is proposed along the east side of the on-site wetland. FILE NO L02P0005 Page 4 G. H. While this subdivision as presented has been determined to comply with sensiti\/e area provisions, the adjoining plat of Rosemonte currently as designed will either need to shift the street east so that the retaining wall is outside of the BSBL (this would change the street alignment of 145'" Ave SE) or instead propose additional buffor averaging In Rosemonte to allow the BSBL to be shifted wost. According to the Conservation District maps, the site is characterized by a high water table. The sl~e lies within the Honey Creek subbasln of the May Crnek drainage basin. 4. · Vegetation: The west third of the site is heavily wooded with a second and third-growth mixture of coniferous and broad-leafed trees native to the Pacific Northwest. Within the wetland Itself, there is predominately Red Alder. The remaining portion of the site (east 2/3rds) ls primarily covered in pasture grasses. Scattei-ed evergreen/deciduous trees and brush occur in limited numbers. · 5. Wildlife: Two Red Tall Hawk Nests were identified back in 2001 with the central one determined to be abandoned and the northerly one active. The applicant has proposed on the most recent plat plan location of lots at a minimum of 250 feet from the nest. Such birds are not listed as threatened or endangered species nor are they protected In the Urban area of King County. other small birds and animals undoubtedly inhabit this site; and larger species may visit this site on occasion, however, the population of species is limited due to lncreased nearby development. 6. Mapped Sensitive Areas: The Sensitive Areas Map Folio Indicates that there Is a wetland which crosses over from this property onto the property to the north and south. NEIGHBORHOOD CHARACTl;RISTICS: The prope~ lies in southeast King County, north of the City of Renton on the west side of 148 Ave SE which provides arterial access to the site. The site ts designated as Urban and is within the urban growth boundary. In recent years there have been numerous plats in the local area approved by King County. This East Renton area Is In transition from a rural residential area to a low to medium density urban setting. On this site there Is an existing residence and detached garage and the remaining upland portion is manly In pasture: The forested area on the wost third Is the lowest portion of the site and contains the wetland noted In this report This prdperty and other surrounding property In the Urban area are zoned R-4 (Residential~ 4 du's per acre). Properties east of 148° Ave SE and north of SE 120• St. are zoned RA-5 (Rural Area -1 du per 5 acres). Additionally, the.so properties are outside the Urban Growth Boundary, 148° Ave SE is a 60 foot pub\lc right-of way and the right-of-way is within the Urban Growth Boundary. SUBDtVISlON DESIGN FEATURES: 1. Lot Pattern and Density: The proposed lot and street layout is in conformance with King County Codes (i.e. KCC 21A and the 1993 King County Road Standards. Density calculation for the plat average is 3.9 d.u.'s per acre based on total acreage of 17.01 acres. Code would allow 68 lots under the base density provisions. Minimum density code provisions require development of at least 35 lots. Density of the net buildable area of 11.88 acres would be 5.6 dwelling units per acre. The 66 lots are . generally 5,000 square feet In area and have a width typically of 50 feet. See Attachment 6 for the Density & Dimension Calculation Worksheet for further details. Additionally, Tract Ea future growth development tract is proposed between wetlands on the far wast potion of the property. This tract is 48,128 square feet in size and is FILE NO L02P0005 Page 5 almost totally surrounded by sensitive area/wetlands except on the south tract boundary which also is the south property line of the plat. Future development of this tract would be subject to Critical Area Code requirements which could require additional_ property be set aside as buffers. 2. Internal Circulation: Lots will front onto the internal public streets that provide access within the subdivision and exits out to 148th Ave SE. Additionally street stubs connections are planned which would provide access to properties both north (145~ and 147~ Ave SE) and south (145'" Ave-SE). See the proposed plat layout, Attachment 1 to this report. The applicant has stated that the future development tract could be served with access from the southerly abutting property, however though preappllcatlon review of the abutting parcel, it appears access to the proposed r.uture development tract on East Renton could not be provided due to the extent of wetlands to the south on the abutting parcel when applying code llmltatlons of KCC 21A.24. · 3. Roadway Section: As proposed by the applicant, 1481h Ave SE frontage will be improved with urban ·improvements, Including curb, gutter, and sidewalks. A road variance was approved allowing an alternative design for Improvement (see Attachment 3. The Internal public street planned as SE 119~ St will be improved _as a subcolleclor street, as will the proposed 145" Ave SE from SE 119~ to the south property line. SE 120'' St and 147'' Ave SE south of SE 11 gth St will function as a subaccess street and 146~ Ave.SE will be a minor access. 4. Drainage: The proposed subdivision Includes an underground storm water vault located within Tract G shown on the preliminary plat. Since the drainage facility will be located below ground, the surface area will be utilized as a recreation space for the future homeowners. A portion of the subdivision drains northerly to the property currently proposed for development as the Rosemonte subdivision. Since tha King County drainage manual requires storm water to be discharged at the natural location, the applicant requested a drainage adjustment to divert storm water" froin the northern portion of the site to the proposed storm vault. This adjustment was approved·by King County in 2002: however, the applicant revised the proposed drainage plan in 2003 after the adjacent parcel of land was proposed for development as the Rosemont subdivision. The current drainage plan shows an offsite detention pond located wlthln Rosemonte which is designed to accommodate drainage for.Rosemonte and the northern portion of East Renton. To allow an off site drainage facility, the applicant requested approval for a second drainage adjustment to allow a shared facility for both subdivisions. As shown on the preliminary plat map for Rosemonte, a detention pond Is proposed within Tract C (per 3/B/06 revised plan) which will provide designs for flow control and water quality treatment. The dralnago adjustments for the original diversion and the subsequent adjustment for a sh_ared facility ate both shown in the staff report as ·Attachments 4 and 5. In accordance with tha 1998 King County drainage manual, the drainage facilities will be designed for Level 1 flow control and basic water quality treatment. Tho site is located within the Honey Creek subbasin which drains to the larger May Creek watershed. The King County basin plan for May Creek has evaluated the Honey Creek basin and recommends that future development in this area use the level one flow control standard as shown In the drainage manual. A review of the downstream corridor in the immediate vicinity of the project did not identify any specific drainage problems. After construction and acceptance of the storm water vault and detention pond for the subdivisions, the drainage facilities will be maintained in the future by King County. FILE NO L02P0005 Page 6 I. TRANSPORTATION PLANS: 1. Transportation Plans: The King County Transportation Plan indicates that 148"' Avenue Southeast (adjoining east boundary) is doslgnated as a collector arterial. The King County Non-motorized Transportation Plan indicates 148~ Avenue Southeast as part of the plan and is to accommodate bicycles as a shared roadway. 2. Subdivision Access: The East Renton subdivision will provide urban road improvements with curb, gutter, and sidewalk for both the internal roads and frontage improvements along 1481h Ave SE. During preliminary 'r0view of the roadw~ys, King County detormined that the existing crest vertical cuJVe along 1481h Ave SE did not meet design standards for stopping sight distance. Due lo the substandard road design and tho need for improving the property frontage, the applicant submitted a road variance application to evaluate design requirements for the roadway. As shown in Attachment 3, the road variance was approved by the King County Department of Transportation to allow reconstruction of the frontage road to provide 455 feet of stopping sight distance. To provide adequate walking conditions !or school children, an offsite sidewalk will also be provided along 1481n Ave SE, extending northorly from the site to an existing crosswalk at the intersection of SE 11ih Street. Due to the topography and existing road improvements near the crosswalk, the applicants design for the . sidewalk shows a rockery located outside the right-of-way on private proper(y. The applicant has contacted the property owner regarding acquisition of a road easement, however this property owner has not clarified in writing a willingness to· negotiate to allow easement rights, therefore final resolution has not been provided at this time. During final engineoring, the applicant will need to obtain an easement for construction on private property or prepare an alternative walkway · design which satisfies the design requirements within the exlsti,ng right-of-way. It is possible that the applicant could design improvements on the east side of 148'h that would meat the walkway requirements, as well. Access into the plat will be provided off 148• Ave SE. The planned stub street to the south may someday provide for a secondary access out to 1481h Ave SE. and will · Improve the connectivity between subdivisions. 3. Traffic <,eneration:' It _is expected that approximately 660 vehicle trips per day. will be generated with full development of the proposed subdivision_. This calculation includes service vehicles (i.e., mail delivery, garbage pick"."up, school bus) which may currently serve this neighborhood, as well as work trips, shopping, etc. 4. Adequacy of Artorial Roads: This proposal has been reviewed under the criteria In King County Code 14.70, Transportation Concurrency Management; 14.80, Intersection Standards; and King County Code 14.75; Mitigation Payment System. a. King County Code 14.70 -Transportation Concurrency Management: The Transportation Certificate of Concurrency dated April 9, 2002, Indicates that transportation Improvements or strategies will be in place at the lime of development, or that a financial commitment is in place to complete the improvements or strategies within six (6) years, according to RCW 36. 70A.070(6). b. King County Code 14:80 -Intersection Standards: The existing arterial system requires Improvements to accommodate the increased traffic volume generated by this proposal. As a result, DOES issued a MONS which calls for the mitigation needed to address the Impacts resulting from added traffic onto local intersections rather than requiring an EIS prior to action on the preliminary plat application, see Section D of this report. The appeal period for the Threshold Determination closes January 11, 2007. FILE NO L02P0005 Page 7 c. King County Code 14.75-Mitigation Payment System: King County Code 14.75, Mitigation Payment System (MPS), requires the payment of a traffic impact mitigation fee (MPS fee) and an administration feo for each single-family residential lot or unit created. MPS fees are determined by the zone in which tho site is located. This site is in Zone(s) 442 per the MPS/Quarterseclion list. MPS fees may be paid at the time of final plat recording, or deferred until building permits are issued. The amount of the fee will be detennined by the applicable fee ordlnanco at the time the fee is collected. J. PUBLIC SERVICES: 1. Schools: This proposal has boon reviewed under RCW 58.17.110 and King County Code 21A.28 (School Adequacy). a. School Facllltles: Students from the proposed plats of East Renton and Rosemont will be served by Apollo Elementary, Maywood Middle, and Liberty High School. As a result of the passage of time (nearly 5years between the April 2002/East Renton Request for School Information and the date of preparation of this staff report) following the receipt of the response from the District, the STC has reconfirmed the school service boundaries by checking tho School District's web site, and the 'service area'/Attendance map pages for each of the applicable schools. b. School Impact Fees: Currently the Issaquah School District required that an impact fee per lot be imposed to fund school system Improvements to serve new development within this district. Payment of this too in a rriariner consistent with K.C.C. 21 A.43 will be a condition of subdivision approval. c. School Access: Apollo Elementary School ls located to the north of tho subject subdivision, off of SE 1171" Street, east of 148~ Avenue SE. According to information provided by the Issaquah School District, stud.ants of this age gioup would be provided bus transportation to the school due to cond!Uons along the walkway route unless sidewalk improvements would be provided along 148~ Avenue SE (see Condition 12). The Subdivision Technical Committee (STC) has recommended that, in addttion to the urban shoulder improvements acrosS the frontage ofth8 proposed subdivision, that urban improvements be provided across the frontage of the abuttin9 (and, related by ownership, access and required off-site mitigation) proposed plat of Rosemonte (FKA Ironwood), DOES File# L03P0018. The existing designated crossing across 148'" Avenue SE Is located immediately off-frontage from the ~orthem subdivision ·boundary of Rosemonte, therefore, the STC believes that additional improvements -off~site to both plats' frontage -is necessary to provide adequate walkways for this ago group. Such improvements should meet the urban standards for sidewalks and curbs due to location on the north side of the intersection, the need for a railing, and traffic volumes on 148°' Ave SE. Additionally, due to the potential need to construct a curb and gutter section along the east side of 141i'" Avenue SE (lo re-profile 148fu Avenue SE, end maintain the resultant slope grading within existing right-of-way), the STC recommends that if the project proponent elects lo Implement this option, that a graded surface be provided to ensure that school-age p_edestrians are provided an acceptable-width walkway surface behind the curbing. Maywood Middle School is located to the south of the proposed subdivision, on the opposite side of Southeast 1281" Street, in the 14400 block of 1681" Avenue SE. Students of this age group are provided bus transportatio111 to/from the school due to dlstance and the traffic conditions along any potential walking routes. The District had requested that a safe waiting area be provided at the Intersection of Southeast 120~ StreeV148'" Avenue ~E. The STC recommends in the plat conditions that a level concrete 'pad' be constructed to augment the required sidewalk Improvements at/near the FILE NO L02P0005 Pages I indicated intersection. See Condition 8.h. This improvement will serve the middle and high school-aged residents of both 1he subject subdivision and the proposed plat of Rosemonte. liberty High School is located lo the south of the proposed subdivision, on the opposite side of Sou1heast 1281" Street, in the 15500 block of Southeast · 1361h Street. Students of this age; group are provided bus transportation to/from the school due to distance and the traffic conditions along any potential walking routes. The Issaquah School Dis1rict had requested, In its April 2002 response, that a safe waiting area be provided at the intersec1ion of Southeast 120 1" StreoU148~ Avenue SE. The STC recommends in 1he plat conditions that a level concrete 'pad' be constructed to augrnent the roquired sidewalk Improvements aUnear the indicated intersection. See Condition 8.h. This improvement will servo the middle and high school-· aged residents of both the subject subdivision and the proposed plat of Rosemonte. 2. Parks and Recreation Space: K.C.C. 21A.14 requires subdivisions in the UR and R zone classifications to either providO on .. site recreatiOn space or pay a fee to the Parks Division for establlshment and maintenance of neighborhood parks. At this time, it does not appear that the applicant's plan wlll provide suitable recreation space as required by code. Additionally, there are no nearby parks where a "fee in liou" could be applied. In total 25,740 square feet of rocreatlonal area is required (390 square feet per lot). East Renton Tract Cal 1he comer of 147~ Ave. SE. with SE 11'1~ St. Includes 9,335 sf and Tract G at the corner 145• Ave. SE. with SE 11t• St. is shown to contain 16.407 sf. Together these tracts equal 25,742 sf., however all ofTract G currently does not fit the definition of flat, dry and usable area. With placement of a drainage vault on the tract, that recreation area on top tho vault and any additional area in the tract contoured for recreational use (all 5% slope or !ess) would be counted towards the total needed square footage. Staff estimates that the vaul1 has an 8,400 sf surface area and given the existing 1opography not all the remaining tract area could possibly be counted towards the total flat, dry, useable area due to topography beyond the tract Attachment 7, shows the limiting factors in the cross section of an earlier configuration of Tract G (labeled Tract C). Options to comply with minimum area · would Include adding add~ional area to either tho current Tract C or Traci G. Staff would not be In support of creating a third tract for recreation, except if such tract was connected to either Tract C or Tract G by trail (i.e. conversion of Tract E to recreation area minimally providing a trail). · K.C.C. 21A.14.190 requires subdivisions to provide a 1oUchildron play area within the recreation space on site and two additional recreational facilities as listed in K.C.C. 21A.14.190 E.2. Staff would support a plan with at least one recreation facllily on ono tract and two on the other tract. Both recreation tracts are localed on tracts easily accessible to plat residents. Tract C is near the plat entry on a comer so to provide good visibility and access. Tract G is at a location that takes advantage of the views into the sensitive area (wetland) west · of the 1ract. Also the tract functions in providing stonm detention. The request would not comply with all provisions of KCC 21.14.180 F. and therefore per code, KCC 21.14.180 C. applies to both recreation tracts. 3. Fire Protection: The Certificate of Waler Availability from Water District# 90 Indicates that water will be available to the site In sufficient quantity to satisfy King County Fire Flow Standards, Prior to final recording of the plat, the water service facilities must be reviewed and approved per King County Fire Flow Standards. All future residences constructed within this subdivision are required to be sprinklered NFPA 130 unless the requirement is removed by the King County Fire FILE NO L02P0005 Page 9 ' .. K. MarShal or his/her designee. The Fire Code requires all portions of the exterior walls of structures to be within 150 feet (as a person would walk via an approved route around the building) from a minimum 20-foot wide, unobstructed driving surface. To qualify for removal of the sprtnkler requirement driving surfaces between curbs must be a minfmum of 28 feet in width when parking is allowed on one side of the roadway, and at least 36 feet in width when parking is permitted on both sides. UTILITIES 1. Sewage Disposal: The applicant proposes to serve !he subjec.t subdivision by public sewer of tho City of Renton. The City conditioned the extension of sewer to the requirement that the developer sign a covenant allowing for future annexation of the property into the City. (Seo Attachment 2). 2. Water Supply: The applicant proposes to serve the subject subdivision from a public water supply and distribution system managed by Water and District# 90. A Certificate of Water Availability, dated April 4, 2004, indicates this district's capability to serve the proposed development. Dedication of easements to the district for extension of water mains wilt be required. L. COMPREHENSIVE AND COMMUNITY PLAN: 1. Comprehensive Plan: This plat is governed by the 1994 King County Comprehensive plan which designates this area as Urban Residential 4-12 dwelling units per acre. The proposed subdivision is not in conflict with the policies of the Comprehensive Plan. 2. Community Plans: The subject subdivision is located In the Newcastle Planning Area and does not conflict with. the goals, guidelines, and pollclas of the Community Plan. M. STATUTES/CODES: If approved with the recommended conditions In this report, the proposed development wlll comply with the requirements of the County and State Platting Codes and Statutes, and the lots In the proposed subdivision will comply with the minimum dimensional requirements of the zone district. N. CONCLUSIONS: 1. The subject subdivision will comply with the goals and objectives of the King County Comprehensive Plan and will comply with the requirements of the Subdivision and Zoning Codes and other offlclal lend use controls cif King County, based on the conditions for final plat approval. 2. Beyond the typical plat requirements, conditions ara proposed which would require the applicant to provide design plans and documentation that addres~ the items below to the satisfaction of ODES: a. Acquisition of easements from private property owners with property adjacent to 1481h Ave SE are needed to construct road improvements lo 148th Ave SE. as proposed. Acquisitions Includes an easement for a retaining wall to support sidewalk improvements to the existing crosswalk on the north side of at SE 117"' St., and from property owners on the east side of 148ili Ave SE for side slope easements to support the planned profile/elevation change to 148ili Ave SE. FILE NO L02P0005 Page 10 0. Urban ioad improvements on the west side of 1481" Ave SE along the property frontage ( and frontage of Rosemonte) north to the north side of SE 111• St. will satisfy the need for safe waikway access to the school. Should the applicant be unablo to obtain easements, urban road improvements could feasibly be provided on the east side of 148• Avo SE as a means to elimlnate the need for slope easements on the east side of the road and provide an alternative for a safo walking to the school. b. As designed, the plat does not provide for sufficient area to meet code minimum for recreation area. As a means to enlarge either Tract C and/or G, lots proposed could be reduced in size, if needed, and still comply with the minimum standards for size and width without lose of density. Revision to the plat design will be needed to adjust the size recreation area · tract(s) to meet code minimum for recreatlonal.area. c. Tract E (proposed as a future development tract) can not under all reasonable scenarios actually be developed for lots in the future. When development of the south abutting property occurs, access from the south will unlikely be proposed. Such access would require crossing wetland and/or buffer on abutting property that Is not allowed by the code criteria for critical areas in KCC 21 A.24 .. Altemativoly, staff would support adding Tract E: 1) into the sensitive area tract surroundi'ng, 2) des[gnaling tho tract as open space, or 3) designing the tract as recreational area, if served by trail extending from the recreational Tract G to Tract E, whereby Tract E would function as an extension of recreation from Tract G.. · d. Buffer averaging is the preferred alternative to assure the retaining wall In Rosemonteoff 145'" Ave SE is outside of the wetland buffer and BSBL. Should buffer averaging not·provide complete relief from buffer and BSBL limitations, then 145• Ave SE must be shifted east. Alignment of 145• Ave SE within East Renton and within Rosemonte should be coordinated to assure a workable alignment of 145• Ave SE for the two plats. RECOMMENDATIONS: It is recommended that the subject subdivision's East Renton Preliminary Plat Page 1, revised and received March 17, 2006, be granted preliminary approval subject to the following revisions to the plat design and conditions of final approval: 1. . Complianco with all platting provisions of Title 19A of tho King County Code. 2. All persons having an ownership interest In the subject property shall sign on the face of the final plat a dedication that includes the language set forth In King County Council Motion No. 5952. 3. The plat shall comply with the base density and minimum density requirements of the R-4 zone classification. All lots shall meet the minimum dimensional requirements of the R-4 zone classification or shall be shown on the face of the approved preliminary plat, whichever Is larger, except that minor revisions to the plat which do not result In substantial changes may be approved at the discretion of the Department of Development and Environment Services. Any/all plat boundary discrepancy shall be resolved to the satisfaction of DDES prior to the submittal of the final plat documents. As used in this condition, "discrepancy" is a boundary hiatus, an overlapping boundary or a physical appurtenance which Indicates an encroachment, lines of possession or a conflict of title. FILE NO L02P0005 Page 11 4. 5. 6. 7. The applicant must obtain final approval from the King County Health Department. · All construction and upgrading of public and private roads shall be done in accordance with the King County Road Standards established and adopted by Ordinance No. 11187, as amended (1993 KCRS). The applicant must obtain the approval of the King County Fire Protection Engineer for the adequacy of the fire hydrant, water main, and fire flow standards of Chapter 17.08 of the King Count_y / C.ode. · Add.' h OYl cH /µezd W ,d'/Z..._ Final plat approval shaJfrequire full compliance with the drainage provisions set forth in King County Code 9.04. Compliance may result in reducing the number and/or location of lots as shown on the preliminary approved plat. Preliminary review has identified the following conditions of approval, which represent portions of the drainage requirements. All other applicable roquircments In KCC 9.04 and the Surface Water Design Manual (SWDM) must also be satisfied during engineering and final review. a. Drainage plans and analysis shall comply with the 1998 King County Surface Water Design Manual. ODES approval of the drainage and roadway plans is required prior to any construction. b. Current standard plan notes and ESC notes, as established by DOES Englneering RoviAw shall be shown·on the englneerlng plans. c. Tho following note shall be shown on the final recorded plat: "All building downspouts, footing drains, and drains from all impervious surfaces such as patios and driveways shall be connected to the permanent storm drain outlet as shown on the approved construction drawings # on file with DOES and/or the Department of Transportation. This plan shall be submftted with the application of any building permit. All connections of the drains must be constructed and approved prior to the final building Inspection approval. For those lots that are designated for Individual lot infiltration systems. tho systems shall be ccnstructed afthe time of the building permit and shall comply with the plans on file." d. Storm water facilities shall be designed using the KCRTS level one flow control standard. Water quality facilities shall also be provided using the basic water quality protection menu. The size of the proposed drainage tracts may have to lncremse to accommodate the required detel1tion volumes and "{ater quality facilllles. All runoff control facilities shall be located In a separate tract and dedicated to King County unless portions of · the drainage tract are used for recreation space in accordance with KCC 21A.14.180. . e. The applicant has received approval for two drainage adjustment applications regarding designs for the discharge of storm water and a shared facility detention pond. The adjustment decisions are contained within file numbers L02VOOB9 and L04V0103. During final review of the engineering plans, all applicable conditions of the adjustment approvals shall be satisfied including requirements for the shared faciltty located offsite within the plat of Rosemonte. f. As stated in the drainage adjustment decision, the offsite drainage pond shall be designed using the Level 1 flow control standard. Basic water quality standards are also required for design of the facility. If a wet pond facility is provided for water quality, the design shall comply with the 3:-1 flow length ratio as outlined on page 6-72 in the drainage manual. For evaluation of the onsite storm vault and the offstte detention pond, a soils FILE NO L02P0005 Page 1;! report shall be prepared be a geotechnical engineer to evaluate the soils and groundwater conditions. g. For any proposed bypass of storm water from the flow control facility, the final drainage designs shall comply with applicable design requirements in the dra[naga manual as outlined on pages 1-36 and 3-52. h. As required by Special Requirement No. 2 in the drainage manual, the 100-year floodplain boundaries for the onslte wetlands shall be shown on the final engineering plans and recorded plat Access and Roads 8. The proposed subdivision shall comply with the 1993 King County Road Standards (KCRS) Including the following requirements: a. During preliminary review the applicant submitted a road variance application (File No. L03V0049), regarding the crest vertical cuive and substandard stopping sight distance along the plat frontage. In response to tho variance application, the King County Road Engineer provided a decision letter dated October 20, 2004 which approved the variance based upon specific design criteria for constructing 148~ Ave SE. As noted in the variance decision, the crest curve on 148 1h Ave SE must be reconstructed to provide 455 feet of stopping sight distance based upon design criteria with a 2-foot target. The final road improvements and design plans for the project shall demonstrate compliance with all applicable conditions of approval as stated in the variance decision. b. 148" Avenue SE shall be improved along the frontage as an urban collector arterial inclu9ing all deslgri criteria from the road variance decision. In accordance with KCRS 2.02, the curb location shall be designed at 22- feet from the road crown to· provide fu!I width travel lanes and a bike lane. The preliminary doslgn plans for East Renton shows road grading extending outside the right-of-way on the east side of 148~ Ave SE. Ouring final engineering review, the applicant shall acquire easements for any proposed construction on private property or provide an alt6rnat1Ve design which is acceptable to King County for road construction within the existing right-of- way. c. The project entry mad to 148'" Ave SE shall be improved as an urban neighborhood collector. As shown on the preliminary plat, the required right-of-way width Is 56 feel. d. The proposed roads within the subdivision shall be improved using urban design standards and in accordance with the street classiflcations shown on the preliminary plat map . . e. Tract D shall be improved as a private joint use driveway seiving a maximum of two lots. The seiving lots shall have undivided ownership of the tract and be responsible for its maintenance. As specified in KCRS 3.01C, Improvements shall inclu·de an 18 foot paved surface and a minimum tract width of 20 feet. Drainage control shall Include a curb or thickened edg~ on one sido. f. Street trees shall be included in the design of all road· improvements and shall comply with Section 5.03 of the KCRS. g. Street illumination shall be provided along the plat frontage and at Intersections with arterials in accordance with KCRS 5.05 . . FILE NO L02P0005 Page 13 ,; . h. The proposed road improvements shall address the requirements for road surfacing outlined in KCRS Chapter 4. As noted in section 4.01 F. full width pavement overlay is required where widening existing asphalt, unless otherwise approved by King County. I. 148th Ave SE is classified an arterial street which may require designs for bus zones and turn outs. As specified in KCRS 2.16, the designer shall contact Metro and the local school district to determine specific requirements. j. Modifications to the above road conditions may be considered by King County pursuant to the variance procedures in KCRS 1.08. 9. All utilities within proposed rights-of-way must be included within a franchise approved by the King County Council prior to final plat recording. 10. The site plans for East Renton show the northerly road stub for 145'" Ave SE which may extend Into the wetland buffer and associated setback wllhin the Rosemont plat. Duling engineering review for East Renton, a revised road alignment and grading plan shall be provided which demonstrates.that road construction within Rosemonte will comply with applicable sensitive area codes. The revised road design and grading plan may result In modlflcatidn or loss of lots as shown on the preliminary plat. Alternatively, the applicant may seek approval to use buffer averaging as a means to revise the location of the buffer and BSLB to achieve code compliance within Rosemonte. 11. There shall be no direct vehicular access to or from 148'" Ave SE from those lots which abut it. A note to this effect shall appear on the engineering plans and the final plat. 12. The applicant shall provide a safe walking access to Apollo Elementary School with urban improvemenls along the west side of 148th Ave NE.to the existing crosswalk on the north side of SE 117'" St. This improvement Includes urban frontage improvements along property frontage of the Plat of East Renton, urban improvements along frontage of Rosemonte and urban Improvements north to the existing crosswalk on the north side of SE 117th ST. (It Is noted that the adjoining plat of Rosemonte will be subject to urban frontage requirements and urban Improvements north to the existing crosswalk on the north. side of SE 117'" ST.) . · Alternatively, due to the potential need to construct an urban curb and' gutter section along the east side of 148'" Avenue SE (to re-profile 148'" Avenue SE, and maintain the resultant slope grading within existing light-of-way), (he applicant may elect to provide a graded surface on the east side of 14l3th Ava SE to ensure that school-age pedestrians are provided an acceptable-width walkway surface behind the curbing. The walkway shall be doolgned to the satisfaction of the school district and ODES. Mitigation/Impact Fees 13. The applicant or subsequent owner shall comply with King County Code 14.75, Mitigation Payment System (MPS), by paying the required MPS fee and administration fee as determined by the applicable fee ordinance. The applicant has the option to either: (1) pay the MPS fee at the final plat recording, or (2) pay the MPS fee at the time of bulldlng permit issuance. If the first option is chosen, the fee paid shall be the fee in effect at the time of plat application and a note shall be placed on the face of the plat lhat reads, "All fees required by King County Code 14.75, Mitigation Payment System FILE NO L02P0005 Page 14 '' .. (MPS), have been paid." If the second option is chosen, the fee paid shall be the amount in effect as of tho date of building permit application. 14. Lots within this subdivision are subject to King County Code 21A.43, which imposes impact fees to .fund school system improvements needed to serve new development. As a condition of final approval, fifty percent (50%) of the impact fees due for the plat shall be assessed and collected immediately prior to the recording, using tho fee schedules in effect when the plat receives final approval. The balance of the assessed fee shall be allocated evenly to the dwelling units In the plat and shall be collected prior to building permit Issuance. Wetlands 15. Preliminary plat review has identified specific requirements which apply to this project as listed below. All other applicable requirements from K.C.C . . 21A.24 shall also be addressed by the applicant. a. The Class 2 wetland shall have a minimum 50-foot buffer of undisturbed v8getation as measured from the wetland edge. b. Sensitive area tract(s) shall be used to delineate and protect sensitive areas and buffl~rs in development proposals for slibdivisions and shall be recorded on all documents of title of record for all affected lots. c. Buffer width averaging may be allowed by King County if it will provide additional protection to the wetland/stream or enhance there functions, as long as the total area ccntalned In the buffer on the development proposal site does not decrease. ln no area shall the buffer bo less than 65 percent of the required minimum distance. To ensure such functions are enhanced a mitigation plan will be required for the remaining on-site ·sensitive areas. An enhancement plan shall be submitted for review during engineering review. d. A 15-foot BSBL shall be established from the odge of buffer and/or the sensitive areas Tract(s) and shown on all affected lots. e. To ensure long term protection of the Sensitive Areas a split-railed fence of no more than 4 feet in height shall be installed along the Sensitive Area Tract boundaries in the area of proposed lots. Sensitive Area· signs shall be attached to the fence at no less than 100 foot intervals. f. If alterations of streams and/or wetlallds are approved in conformance with K.C.C. 21A.24, then a detailed plan to mitigate for impacts from that alteration will be required to be rovlowed and approved along with 'the plat engineering plans. A performance bond or other financial guarantee will be required at the time of plan approval to guarantee that the mitigation measures are installed according to the plan. Once the mitigation work Is completed to a DDES Senior Ecologist's satisfaction, the performance bond may be replaced by a maintenance bond for the · remainder of the five-year monltorlng period to guarantee the success of the mitigation. Tho applicant shall be responsible for the installatlon, maintenance and monitoring of any approved mitigation. The·mitigation plan must be installed prior to final inspection of the plat. g. Prior to commencing construction activities on the site, the applicant shall temporarily mark sensitive areas tract(s) In a highly visible manner, and these areas must remain so marked until all development propciSal activities In the vicinity of the sensitive areas are completed. FILE NO L02P0005 Page 15 .. h. During engineering plat review the applicant shall provide a wetland hydrology analysis to. demonstrate how the wetland hydrology will be maintained post-construction. i. Detention out-fall structures maybe permitted within tho wetland/stroam buffers, however, structures shall be located in the outer edge of the buffer, ~ possible. All buffer impacts shall be mitigated. 16. Development authorized by this approval may require other state and/or federal permits or approvals. It is the applicant's responsibility to correspond with these agencies prior to beginning work on the site. 17. During engineering reviow, the plan set shall be routed to the sensitive areas group to determine if the above conditions have been met. Geotechnlcal 18. The applicant shall delineate all on-s~e erosion hazard areas on the final engineering plans (erosion hazard areas are defined In KCC 21A.06.415). The delineation of such areas shall be approved by a ODES geologist. The requirements found In KCC 21 /1.24.220 concerning erosion hazard areas shall be met, including seasonal restrictions on clearing and grading activities. Sensltlve Area 19. The following note shall be shown on the final engineering plan and recorded plat: RESTRICTIONS FOR SENSITIVE AREA TRACTS AND SENSITIVE AREAS AND BUFFERS Dedication of a sensitive area tract/sensitive area and buffer conveys· to the public a beneficial interest In tho lend within the tracVsensitive area and buffer. This interest Includes the preservation of native vegetation for all purposes that benefit the public health, safety and welfare, including control of surface water and erosion, maintenance of slope stability, and protection of plant and animal habitat. The sensitive area tracUsensitlvo area and buffer imposes upon all present ood future owners and occupiers of the land subject to the tracUsensitive area and buffer t.he obligation. enforceable on behalf of the public by King County, to leave undisturbed all trees and other vegetation within the tracVsensitive area and buffer. The vegetation within the tract/sonsltlve area and buffer may not be cut, pruned, covered by fill, removed or damaged without approval in writlng from the King County Department of Development and Environmental Services or its successor agency, unless otherwise-provided by law. The common boundary between the tracVsensltlve area and buffer and the area of · development activity must be marked or otherwise flagged to the satisfaction of King County prior to any_clearlng, grading, bulldlng construction or other development activity on a lot subject to the sensitive area tract/sensitive area and buffer. The required marking or flagging shall remain In place until all development proposal activities In the vicinity of the sensitive area are completed. No building foundations are allowed beyond the required 15-foot building setback line, unless otherwise provided by law.· FILE NO L02P0005 Page 16 I ,-- Other 20. The plat design shall be revised to provide the minimum suitable recreation space consistent with the requirements of K.C.C. 21A.14.180 and K.C.C. 21A. 14.190 {Le., minimum area, as well as, sport court[s], chlldren's play equipment, picnic table[s], benches, etc.). a. A detailed recreation space plan (i.e., location, area calculations, dimensions, landscape specs, equipment specs, etc.) shall be submitted for review and approval by ODES prior to or concurrent with the submittal of engineering plats. b. A performance bond for recreation space improvements shall be posted prior to recording of the plat. 21. Tract E shall be revised as a tract which is: a) combined with Track F (sensitive area), b) designated as an open space tract, or, c) designated as recreational area, if served by an approved trail (across wetland buffers) extending from the recreational Tract G and functioning as an extension of recreation from Tract G. Plans for the tract· designation and design, shall comply with codes and shall be to the satisfaction of DOES prior to engineering approval. 22. A homeowners' association .or other workable organization shall be established to the satisfaction of ODES which provides for the ownership and continued maintenance of the recreation, open space and/or sensitive area tract(s). 23. Street trees shall be provided as follows (per KCRS 5.03 and K.C.C. 21A.16.050): a. Trees shall be planted at a rate of one tree for every 40 feet of frontage along all roads. Spacing may be modified to accommodate sight distance requirements for driveways and intersections. b. Trees shall be located within the street right-of-way and planted in accordance with Drawing No. 5-009 of the 1993 King County Road Standards, unless King County Department of Transportation determines that trees should not be located In the street right-of-way. c. If King County determines that the required street trees should not be located within the right-of-way, they shall be located no more than 20 feet from the street right-of-way line. d. The trees shall be owned and maintained by the abutting lot owners or the homeowners association or other workable organization unless the · county has adopted a maintenance program. Ownership and m8intenance shall be noted on the fac,, of the final recorded plat. e. The species of trees shall be approved by DOES if loceted within the right-of-way, and shall not include poplar, cottonwood, soft maples, gum, any fruit-bearing trees, or any other tree or shrub whose roots are likely to obstruct sanitary or storm sewers, or that Is not compatible with overhead utility lines. f. The applicant shall submit a street tree plan and bond quantity sheet for review and approval by DOES prior to engineering plan approval. g. The applicant shall contact Metro Service Planning at (206) 684-1622 to determine if 1481h Ave SE.is on a bus route. If 1481h Ave SE is a bus route, the street tree plan shall also be reviewed by Metro. FILE NO L02P0005 Page 17 ' SEPA h. The street trees must be installed and inspected, or a performance bond posted prior to recording of the plat. If a performance bond is posted, the street trees must be installed and inspected within one year of recording of the plat. At the time of inspection, if the trees are found to be installed per the approved plan, a maintenance bond must be submitted or the potiorm!:lnce bond replaced with a mnlntenance bond, and hold for ono year. After one year, the maintenance bond may be released after DOES has completed a second Inspection and determined that the trees have been kept healthy and thriving. i. A landscape inspection fee shall also be submitted prior to plat recording. The inspection fee is subject to change based on the current county fees. 24. The following have been established by SEPA as necessary requirements to mitigate the adverse environmental Impacts of this development. The applicants shall demonstrate compliance with these Items prior to final approval. (1.) To mitigate the significant adverse impact the plat of East Renton will have on the Intersections of SR 900/148~ Ave SE and SR 900/164~ Ave SE, the applicant shall Install, either iridlvldually or in conjunction with other development projects in this area, the following Improvements at the SR 900/148~ Ave Intersection: • A traffic signal, and • Eastbound and westbound left turn lanes The design for the SR 900/148~ Ave intersection improvements shall be approved by the Washington Stato Department of Transportation (ancj by Kini! County to the extent such improvements are located in County right-of- way). In addition, at a minimum, the existing entering sight distance looking east for the north and south legs of the intersection (602 feet and 386 ,feet, respectively) shall not be reduced as part of the intersection Improvements. Documentation shall be submitted to show this requirement is met. All construction work associated with the lntersectl~n improvements shall. be cofl1pleted between Aprll 181 and-September 301 • This seasonal restriction . shall be clearty ·shown on the final engineering plans. · In lieu of the installation of the above-noteq intersec.tion Improvements prior to final plat approval, the applicant may post a financial guarantee with WSDOT which assures tho installation of these Improvements within two years of the recording of East Renton. ln this event, Intersection improvement design must be approved by WSDOT prior to King County approval of the engineering plans for East Renton. If the above-noted Intersection improvemenls have already been made by others prior to th_e recording of East Renton, or a financial guarantee has been posted by others which assures the installation of these improvements, then the applicant for East Renton shall pay a pro-rata share dollar amount to the developer who hos made the improvements or .. bonded" for the improvements, in an amount proportioned to the lmpacts of East Renton. The pro-reta share dollar amount to be paid shall be set by · WSDOT, and documentation shall be provided by the East Renton applicant to the King County Land Use Services Division to show this payment has boon made, prior to final plat recording. The pro-rata dollar amount to be pald_shall be based on the following: • The final East Renton lot count , The trip distrlbution for East Renton . • The total trips contributed to the Intersection of SR 900.148~ Ave by the plats of Aster Park (LOOP0024), Stone Ridge 9L99P3008), East Re>nton (L02P0005), Shamrock (L02P0014), Rosemonte (aka Ironwood - L03P0018), Martin (L05P0019) and any future land use applications , FILE NO L02P0005 Pag_e 18 ., ' submitted to King County for which compliance with the King County Intersection Standards (KCC 14.80) is requireg at oither the SR 900/1481h Ave Intersection, or the SR 900/164 'Ave High Accident Location. In the event that either King County or WSDOT adopts a formal "latecomer's" system prior to final plat recording, that system may be followed in lieu of the approach described above, at the discretion of the applicant, as long as at a minimum there is a financial guarantee which assures the above-noted intersection improvements will bo installed wlthln two years of the date of recording of the plat of East Renton. [Comprehensive Plan Policy T-303 and King County Code 21A.28.060AJ (2.) Documentation shall be provided to demonstrate to the satisfaction of WSDOT that stopping sight distance (360 feet) is available on the east leg of tho SR 900/1481h Ave intersection. The intersection shall be modified by the applicant, if necessary, so that this stopping sight distance requirement is met on the east leg. In addition,. the applicant shall clear vegetation withi11 the right-of-way along SR 900, east of 1481h Ave., to maximize the entering sight distance for the north and south legs of the Intersection. [Comprehensive Plan Policy T-303 and King County Comprehensive Policy · T-303 and King County Code 21A.28.06bAJ Q. OTHER CONSIDERATIONS: R. 1. The subdivision shall conform to K.C.C. 16.82 relating to grading on private property. 2. Development of the subject property may require registration with the Washington State Department of Licensing, Real Estate Divlslon. 3. Preliminary approval of this application does not limit tho applicant's responsibility to obtain any required permit or license from the State or other regulatory body. This may Include, b~i\not limited to the following: a. Forest Practice Permit from the W~shington State Department of Natural Resources. \" National Pollutant Discharge Eliminal"<!' System (NPDES) Permit from WSDOE. . / ) ") b. Water Quality Modification Permit from WSDOE. · Water Quality Certification (401) Permit from,U.S. Army Corps of C. d. Engineers. / ATTACHMENTS: 1. Preliminary Plat Map 2. Renton Sewer Availability lettor 3. Road Variance/ L03V0049 4. Surface Water Management Variance/ L02V0089 5. Surface Water Management Variance/ L04V0103 6. Density Calculation Worksheet 7. Recreation cross section for Tract G (previously labeled Tract C) FILE NO L02P0005 Page 19 ® King County Department of Development and Environmental Services REVISED State Environmental Policy Act (SEPA) Mitigated Determination of Nonsignificance for East Renton/ L02P0005 Date of Revised Issuance: December 29, 2006 Date of Issuance: December 15, 2006 Project: Location: Applicant/Contact: King County Contact: · King County Permits: This Is a request for a subdivision of 17.01 acres into 66 lots for detached single-family dwellings. The proposed density is 3.9 dwelling units per acre. The lot sizes are predominately 5,000 square feet. · West of 148th Ave SE at approximately SE 120th St. Camwest Real Estate Development, Inc. 9720 NE 120th Place, Suite 100 Kirkland, WA 98034 Contact: Sara Slatten Phone# 425-825-1955 Karen Scharer, Project/Program Manager II Phone# 206-296-7114 or email at karen.scharer@metrokc.gov Formal Subdivision Existing Zoning: R-4 Community Plan: Newcastle Basin: May .Creek Section/Township/Range: 10-23-05 Parcel # 1023059023 Notes: The mitigations have been revised to reference the subject plat of East Renton rather than the previous incorrect reference to other plats. · A. This finding is based on review of the site plan showing the revised proposed development received 3/17//2006, SEPA Environmental Checklists, dated 4/3/2002, Revised Level 1 Downstream Analysis by Triad & Assoc., dated 11/24/2004, Traffic Impact Analysis by Garry Struthers Associates, Inc., received 4/3/2002, Garry Struthers Memorandum dated 1/23/2003, WSDOT correspondence of 2/27/2003 and 3/14/2003, Certificate of Water Availability, dated 4/4/2002, Certificate of Sewer Availability, dated 3/28/2002, Revised Wetlands Study with wildlife habitat study by C. Gary Schulz dated 07/28/2005. B. Issuance of this threshold determination does not constitute approval of the formal subdivision. The application will be reviewed for compliance with all applicable King County Comprehensive Plan Policies and King County Codes which regulate development activities, including the Uniform Fire and Road Standards, Surface Water Design Manual, and the Sensitive Areas Regulations. C. The Residential designation on the Land Use Map of the King County Comprehensive Plan allows for the proposed density. Additionally, this density is within the range per the R-4 Zone. The plat with 66 lots would yield an average density of 3.9 dwellings per acre {based on the site area). The lots will mostly be 50 feet by 100-105 feet with about 5,000 square feet. L02P0005 I REVISED SEPA TD December 29, 2006 .Page 2 D. SWM Adjustment L04V0103 was approved 3/24/05 for a shared facility concept allowing the northeast corner of East Renton to utilize the eastern drainage facility in Rosemonte, the proposed plat immediately north of the subject propertY. E. The subject propertY is located southwest of the intersection of State Route 900 and 148'" Ave. SE. According to the applicant's traffic analysis, this intersection will operate at Level-of- Service "F" following the development of the proposed plat (unless improvements to the intersection are made). Per the applicant's traffic analysis, approximately 51% of the P.M. peak hour trips from the proposed plat will pass through this intersection. The proposed plat will have a significant adverse impact on this intersection per KCC 14.80.030. F. A horizontal curve exists on the east leg of the SR 9001148'" Ave SE intersection. Based on data provided by the traffic engineer for the plat of Shamrock, which was reviewed by the Washington State Department of Transportation (WSDOT), the available stopping sight distance on the east leg of the intersection meets the standards of the Washington State Highway Design Manual. G. WSDOT has concluded that, based on tum lane warrants from the Washington State Highway Desi~ Manual, eastbound and westbound left turn lanes should be constructed on SR 900 at the 148 Ave. intersection. The proposed plat will add vehicular trips to the hazardous westbound left turn movement at this intersection. H. In order to address traffic impacts from the proposed plat, WSDOT has requested that the applicant (along with other development projects that will contribute traffic to the SR 900/146'" Ave. intersection) improve this intersection with a traffic signal and eastbound and westbound left turn lanes. I. The intersection of SR 900/164'" Ave SE is located approximately one mile east of the subject propertY. This intersection of SR 900/1641 " Ave SE. is located approximately one mile east of the subject property. This Intersection has been identified by WSDOT as a High Accident Location, and lies within a High Accident Corridor. The subject plat will contribute approximately 1 O peak hour trips to this intersection and WSDOT and the King County Department of Transportation have concluded that the subject plat will have a significant adverse impact at the intersection. The installation of a traffic signal at the 1481 " Ave. SE/SR 900 intersection will mitigate the impact of the proposed plat on the 1641" Ave. intersection, by diverting traffic away from the 1641" intersection to the 1481" intersection, where following signalization, certain turning movements can be made more safety. J, King County Road Engineer reviewed and granted road variance approval on 10/20/2004 for Road Variance L03VD049 the variance approved approval was for a 620 -foot vertical curve with 455 feet of stopping sight distance, utilizing a two-foot target. Additionally approved is the slight grade break (under 1 %) at the north end of the vertical curve. Threshold Determination The re~ponslble official finds that the above described proposal does not pose a probable significant adverse impact to the environment, provided the mitigation measures listed below are applied as conditions of permit issuance. This finding is made pursuant to RCW 43.21 C, KCC 20.44 and WAC 197-11 after reviewing the environmental checklist and other information on file with the lead agency and considering mitigation measures which the agency or the applicant will implement as part of the proposal. The responsible official finds this information reasonably sufficient to evaluate the environmental impact of this proposal. Mitigation List The following mitigation measures shall be attached as conditions of permit issuance. These mitigation measures are consistent with policies, plans, rules, or regulations designated by KCC 20.44.080 as a basis for the exercise of substantive authority and in effect when this ' L02P0005 / REVISED SEPA TD December 29, 2006 Page 3 threshold determination is issued. Key sources of substantive authority for each mitigation . measure are in parentheses; however, other sources of substantive authority may exist but are not expressly listed. 1. To mitigate the significant adverse impact the plat of East Renton will have on the intersections of SR 900/1481 h Ave SE and SR 900/1641h Ave SE, the applicant shall install, either individually or in conjunction with other development projects in this area, the following improvements at the SR 900/1481h Ave intersection; • A traffic signal, and • Eastbound and westbound left turn lanes The design for the SR 90011481h Ave intersection improvements shall be approved by the Washington State Department of Transportation (and by King County to the extent such improvements are located in County right-of-way). In addition, at a minimum, the existing entering sight distance looking east for the north and south legs of the intersection (602 feet and 386 feet, respectively) shall not be reduced as part of the intersection improvements. Documentation shall be submitted to show this requirement is met. All constructio~ work associated with the intersection improvements shall be completed between April 1'1 and September 30'". This seasonal restriction shall be clearly shown on the final engineering plans. In lieu of the installation of the above-noted intersection improvements prior to final plat approval, the applicant may post a financial guarantee with WSDOT which assures the installation of these improvements within two years of the recording of East Renton; In this event, intersection improvement design must be approved by WSDOT prior to King County approval of the engineering plans for East Renton. If the above-noted intersection Improvements have already been made by others prior to the recording of East Renton, or a financial guarantee has been posted by others which assures the installation of these improvements, then the applicant for East Renton shall pay a pro-rata share dollar amount to the developer who has made the improvements or "bonded" for the improvements, in an amount proportional to the Impacts of East Renton. The pro,rata share dollar amount to be paid shall be set by WSDOT, and documentation shall be provided by the East Renton applicant to the King County Land Use Services Division to show this payment has been made, prior to final plat recording. The pro-rata dollar amount to be paid shall be based on the following: • The final East Renton lot count • The trip distribution for East Renton • The total trips contributed to the intersection of SR 900.1481h Ave by the plats of Aster Park (LOOP0024), Stone Ridge 9L99P3008), East Renton (L02P0005), Shamrock (L02P0014), Rosemonte (aka Ironwood -L03P0018), Martin (L05P0019) and any future land use applications submitted to King County for which compliance with the King County Intersection Standards (KCC 14.80) is required at either the SR 900/148'" Ave intersection, or the SR 900/1641" Ave High Accident Location. In the event that either King County or WSDOT adopts a formal "latecomer's" system prior to final plat recording, that system may be followed in lieu of the approach described above, at the discretion of the applicant, as Jong as at a .• i, L02P0005 / REVISED SEPA TD December 29, 2006 Page4 minimum there is a financial guarantee which assures the above-noted intersection improvements will be installed within two years of the date of recording of the plat of East Renton. [Comprehensive Plan Policy T-303 and King County Code 21A.28.060A] 2. Documentation shall be provided to demonstrate to the satisfaction of WSDOT that stopping sight distance (360 feet) is available on the east leg of the SR 900/148'" . Ave intersection. The intersection shall be modified by the applicant, if necessary, so that this stopping sight distance requirement is met on the east leg. In addition, the applicant shall clear vegetation within the right-of-way along SR 900, east of 148th Ave., to maximize the entering sight distance for the north and south legs of . the intersection. [Comprehensive Plan Policy T-303 and King County Comprehensive Policy T-303 and King County Code 21A.28.060A] , Extended Period for Comments and Appeals The SEPA determination may be appealed in writing to the King County Hearing Examiner. Written c6mments or a notice of appeal must be filed with the Department of Development and Environmental Services (DOES) at the address listed below prior to 4:30 p.m. on January 22, 2007 be accompanied with a filing fee of $250.00 payable to the King County Office of Finance .. Please reference the file numbers when corresponding. If a SEPA Appeal is filed, the appellant must also file a Statement of Appeal with ODES at the address listed below prior to 4:30 p.m. on January 22, 2007. The Statement of Appeal shall identify the decision appealed (including the file number) and the alleged errors in that SEPA decision. The Statement of Appeal shall state: 1) specific reasons why the decision should be reversed or modified; and 2) the harm suffered or anticipated by the appellant, and the relief sought. The scope of an appeal shall be based on matters or issues raised in the Statement of Appeal. Failure to timely file a Notice of Appeal, appeal fee or Statement of Appeal, deprives the Hearing Examiner of jurisdiction to consider the appeal. Comment/appeal deadline: Appeal filing fee: Address for comment/appeal: 4:30 PM on January 22, 2007 $250 check or money order made out to the King County Office of Finance King County Land Use Services Division 900 Oakesdale Avenue SW Renton, WA 98057-5212 ATTN: Current Planning Section December 29. 2006 Date Signed ~ King County Department of Development and Environmental Services 900 Oakesdale Avenue Southwest Renton, WA 98057-5212 206-296-6600 TIY 206-296-7217 August 27, 2008 Jennifer Reiner CamWest Development 9720 NE 1201h Place, Suite 100 Kirkland, WA 98034 RE: Plat of East Renton & Rosemente (ODES File No. L02P0005 and L03P0018) Recreation Space Plan Activity No. L07MI072 Dear Ms. Reiner: This is in response to your August 17, 2007 submittal requesting approval of the landscape and recreation space plan for the Plat of East Renton & Rosemente, and the additional information received August 25, 2008. We have reviewed your submittal, and with the following conditions and additions, approve it as submitted: 1. The equipment (structures, benches, picnic table, etc.) shall meet at a minimum, Consumer Product Safety Standards and be appropriately anchored. 2. Walkways/Trails shall be installed from the sidewalk to the play areas. Walkways shall be constructed of a material and grade that is Americans with Disabilities Act (ADA) accessible. 3. Street trees, significant tree retention, if any, shall be reviewed with the engineering plans and are not part of this approval. A revised recreation/landscape plan may be required, in the event modifications associated with a significant tree plan and/or drainage facilities are required The landscaping and recreation space improvements ·(i.e. play structures) must be installed and inspected or a performance bond posted, prior to plat recording. The amount of the bond has been established at $104.727 .22. This includes landscaping, equipment, surfacing materials, etc. The bond amount includes a thirty- percent contingency, and fencing. An inspection fee is also due prior to recording. This fee covers the cost of an installation inspection and a maintenance inspection. The amount of the inspection deposit will be determined by the Land Use Inspection Section (LUIS). If a performance financial guarantee is posted, the improvements must be installed within two year's from the date of recording. At the time of inspection by the Land Use Inspection Section, if the improvements are fully installed per the approved plan, the performance financial guarantee may be redu.ced. Enclosed is a copy of the approved plans and bond quantity worksheet for your records. If you have any questions, please call me at (206) 296-6673. If you have questions regarding the financial guarantee please contact Carol Rogers at (206) 296-7250. Questions regarding the inspection process may be directed to the Land Use Inspection Section (206) 296-6642. hannon Dorr ProjecUProgram Manager II Current Planning Section Encl: Approved recreation plan, approved August 27, 2008 Bond Quantity Worksheet, approved August 27, 2008 Cc: Carol Rogers, Fiscal Specialist Ill Joanne Carlson, Administrative Assistant 11-· Steve Townsend, Engineering Supervisor File · .. LANDSCAPE BOND QUANTITY FORM King county PROJECT NAME: East Renton/ Rosemonte -Recreation L02P0005 / L03P0018 ;iirE~;: :EB ~ ~ VJ ~ g,· DES PROJECT#: Renton, Wa m n 98055-1219 AUG 2 5 2nnA _A_D_D_R_E_s_s_: _______ w_e_st_o_f_1_4_8t_h_A_v_e_S_E_; _K_in_g_c_._ PREPARED BY: Margie Korve, Triad Assoc. K.C. D.D.E.S. DATE PREPARED: 8/25/2008 DRAWING DATE: 8/25/2008 Bonds are based upon required landscaping only and will be posted for performance and/or maintenance. Required landscaping includes perimeter landscaping, surface parking area landscaping, (KCC 21A 16) and any landscaping required by SEPA environmental review. The maintenance period is for the life of the project, however, after posting for maintenance, the performance bond will be reduced by 30% ($1,000.00 minimum) and be held for a two year period. Upon re-inspection of the site the bond will be released if the site has been properly maintained (21A 16.180). If the project has not been maintained and there are dead trees, shrubs, ground cover, or other deficiencies noted in the required landscaping the bond will be held until the deficiencies are corrected I UNIT PRICE UNIT TYPE QUANTITY SOD LAWN AREAS $500.00 MSF (1000 SQ. FT) 0.00 HYDROSEEDING: LAWN $50.00 MSF (1000 SQ. FT) 9.46 HYOROSEEDING: HILLSIDE PLANTING $50.00 MSF ( 1000 SQ. FT) 2.70 SOIL PREPARATION A. TOPSOIL: TREES & SHRUBS (6 INCHES DEEP) $25.00 CY (CUBIC YARD) 177.00 TOPSOIL: LAWN AREA (4 INCHES DEEP) $25.00 CY (CUBIC YARD) 117.00 B. MULCH (2 IN.): $24.00 CY (CUBIC YARD) 28.00 C. PEAT MOSS (TWO INCHES DEEP) $2.30 SY (SQUARE YARD) 0.00 D. COMPOST (3 INCHES DEEP & TILLING) $26.00 CY (CUBIC YARD) 88.00 E. FERTILIZER: included w/tree and shrub plant'a $6.67 CY (CUBIC YARD) 0.00 PLANT MATERIALS A. DECIDUOUS TREES (INTERIOR LANDSCAPING OR OTHER REC'D LANDSCAPING) 2.0" CALIPER /minimum height 10') $250.00 COST & LABOR 0.00 1.75" CALIPER (minimum height 10') $200.00 COST & LABOR 5.00 MUL Tl TRUNK (minimum height 6') $80.00 COST &LABOR 4.00 B. EVERGREEN TREES FIVE 15) FEET OR ABOVE $150.00 COST&LABOR 14.00 C. SHRUBS {5 Gallon) $45.00 COST & LABOR 0.00 C. SHRUBS {2 Gallon) $30.00 COST & LABOR 543.00 SHRUBS (1 gallon) $10.00 COST & LABOR 188.00 PRICE $473.00 $135.00 $4,425.00 $2,925.00 $672.00 $2.288.00 $0.00 $1,000.00 $320.00 $2,100.00 $16,290.00 $1.880.00 SUB TOTAL BOND AMOUNT BOND AMOUNT SUBTOTAL: $32,508.00 PAGE 1 OF 2 PAGE 2 OF 2 I • I UNIT PRICE UNIT TYPE QUANTITY PRICE I D. GROUND COVER 11 Gallon) $8.00 COST &LABOR 0.00 GROUND COVER £4 inch Potsl $4.00 COST & LABOR 0.00 MISCELLANEOUS TREE STAKES $2.65 PER ST AKE & LABOR 46.00 $121.90 FENCING LINEAR FOOT 3.5 FT. WOOD SPLIT RAIL (tract C) $8.00 INCLUDES LABOR 180.00 $1,440.00 10 FT. VINYL CLAD CHAIN LINK $18.00 INCLUDES LABOR "0.00 IRRIGATION IRRIGATION: Tracts C, H & L /Permanent) $0.50 SQUARE FOOT 17,987.00 $8,993.50 IRRIGATION: Tracts H & I -Trail Area (Temporary) $0.25 SQUARE FOOT 3,740.00 $935.00 ADDITIONAL ITEMS SURFACES CONCRETE PAVING/ WALK $15.00 SY (SQUARE YARD) 149.00 $2,235.00 4 FT. SOFT SURFACE TRAIL $4.00 LF INCLUDES LABOR 1,443.00 $5,772.00 TIMBER STAIRS $2,000.00 LUM SUM 1.00 $2,000.00 5 FT. GRAVEL SURFACE TRAIL $8.00 LF INCLUDES LABOR 129.00 $1,032.00 PLAYGROUND EQUIPMENT: All Unit Prices include delivery and installation PLAY STRUCTURE {Installation included) $15,000.00 LS (LUMP SUM) 1.00 $15,000.00 PLAY SURFACING ( 12 INCH DEPTH} -Delivered $2,500.00 LS (LUMP SUM) 1.00 $2,500.00 PLAY SURFACE TIMBER EDGING $7.00 LF (INCLUDES LABOR' 105.00 $735.00 BASKETBALL SYSTEM: Pole, Backboard, Rim $1,650.00 LS (LUMP SUM) 1.00 $1,650.00 BASKETBALL POLE SLEEVE: 4 inch surface sleeve $603.00 LS /LUMP SUM) 1.00 $603.00 BASKETBALL SYSTEM & SLEEVE INSTALLATION $450.00 LS {LUMP SUM) 1.00 $450.00 TETHER BALL (installation included) $300.00 LS 'LUMP SUM) 1.00 $300.00 SITE FURNISHINGS: All Unit Prices Include deliverv and installation WOOD BENCHES (installation included) $538.00 EACH 4.00 $2,152.00 RECYCLE PLASTIC BENCHES /installation included) $766.00 EACH 2.00 $1,532.00 PICNIC TABLES (installation included) $1,075.00 EACH 0.00 TRAIL SIGN $300.00 EACH 2.00 $600.00 THIRTY-PERCENT CONTINGENCY FEE $24,167.82 TOTAL BOND AMOUNT TOTAL BOND PRICE: , / $104,727 .2i (o' Note: ~. ~~~ 1. Street trees are not calculated in this bond quantity worksheet, but are included in a separate Street Tree Bond Quantity Form. PAGE 2 OF 2 15' BSB~' ,:v 7 71?ACT F // S(N,S!!' VE AfJ£_,;;, / ',, ··~ -~ ,,.. _,, / / '-/ --- ' ' -. POR OF THE NE 1/4 OF THE SE 1/4 & THE ', ___ . "-"---~· ____ , __ _ SE 1/4 OF THE NE -----··--·--- 1/4, ALL IN SEC. 10, TWP. 23 N., RGE. 5 E., W.M. ! / 11 I I l J /1 I I I I I FRAME AND GRATE LEGEND (J) ROLLED CURB FRAME AND VANED GRATE <zi STANDARD FRAME AND VANED GRATE Q) STANDARD FRAME AND SOLID LOCKING LID NOT£: "'~ ~J r--i J -- UNDERGROUND I • ' ' ' ' SE 118TH ST KEY MAP NOT TO SCALE SCALE: 1" = 40' 0 20 40 80 ~ SE£ SHEET 14 FOR 148TH A\.£' SE FRONTAGE IMPROVEMENTS. PROVIDE FALL PROTECTION FENCING AT TOP 0/f ANY WALL/ROCKERY 1'ALl£R THAN 30• THERE SHALL 8£ NO D 'R£CT VEHICULAR ACCESS TO OR FROM 148TH A VE SE FROM TH£ LOTS WHICH ABUT THIS STREET CLEANOUT SCHEDULE LOT# TOP SIZE AND (MATCH FG) INVERT 9 453.0 6" 1£ 449.5 10 454.5 6" 1£ 448.9 11 455.9 6" IE 448.J 12 457.4 8" 1£ 447.6 13 459.0 6" IE 455.0 14 459.9 6" IE 456.4 15 460.5 6" 1£ 455.8 16 460.2 8" 1£ 455.0 17 459.0 6" /£ 455.5 18 466.9 8" IE 463.0 19 468.2 6" IE 465.0 20 469.8 6" IE 466.2 21 470.1 6" IE 466.4 22 469.2 6" IE 465.6 23 467.8 6" IE 464.6 24 466.6 8" IE 462.6 25 464.7 6" IE 461.6 26 463.6 6" 1£ 460.2 29 475.1 8" IE 471.4 JO 477.9 8" IE 473.8 31 480.7 8" 1£ 476.0 32 48,'.~.5 8" IE 476.5 JJ 485.8 8" IE 477.0 34 488.6 6" IE 485.J 35 490.6 6" IE 487.6 36 488.9 5• 1£ 485.9 37 484.0 6" IE 480.0 38 503.0 8" IE 499.1 39 505.7 8" IE 502.1 40 508.0 6" IE 505.1 41 510.7 6" IE 507.6 42 512.0 6" IE 509.0 43 515.0 6" IE 510.5 44 514.0 6" IE 510.0 45 512.7 6" IE 508.9 46 512.5 6" IE 509.0 47 511.7 6" IE 508.J 48 509.7 6" IE 506.7 49 506.5 8" IE 503.0 50 503.7 5• IE 500.0 51 500.5 6" IE 497.0 54 484.6 6" IE 482.0 55 487.8 6" IE 484.8 56 490.7 6" IE 487.6 57 493.1 6" IE 490.4 58 495.9 6" IE 493.2 59 500.1 6" IE 496.J 60 512.5 6" IE 499.0 61 512.2 6" IE 498.4 62 510.6 6" IE 497.1 63 508.9 8" IE 493.9 64 504.9 8" IE 490.9 65 501.9 8" IE 488.0 ALL CATCH BASINS AR£ TYPE 1 UNLESS OTHERWISE NOTED. ALL STORM DRAIN PIP£ SHALL CONFORM TO SECTION 7.03 OF TH£ 1993 KING COUNTY ROAD STANDARDS. TH£ FOLLOWING PIPES. SP£C/F/£D IN SECTION 9-05 OF TH£ ~DOT/APWA STANDARD SPECIF/CA T/ONS AR£ ALLOWE'D: PLAIN AND REINFORCED CONCRETE STORM S£WE'R PIP£. DUCTILE IRON, POL YVINYI.. CHLORIDE (PVC), UN£D CORRUGATED POL YE:THYl..£N£ (LCP£), AND SOLID WALL POL YE:THYl..£N£ (SKF£) PIP£. CAUTION LOCATION OF EXISTING UT/UT/ES SHOWN IS APPROX/MAT£ AND MAY NOT 8£ ACCURA T£ OR ALL INCLUSIVE. IT IS TH£ CONTRACTOR'S R£SPONSIBIUTY TO FIELD VERIFY LOCATION OF UT/UT/ES PRIOR TO PROCEEDING WITH CONSTRUCTION. YOU MUST CALL 1-800-424-5555 NOT LESS THAN 2 FULL BUSINESS DA I'S BEFORE BEGINNING £XCA VA TION WHERE ANY UNDERGROUND UT/UT/ES MAY 8£ LOCATED. FAILURE TO DO SO COULD MEAN BEARING SUBSTANTIAL REPAIR COSTS. KING COUNTY D.D.E.S. Review Engineer Completion Date Senior Engineer Completion Dote NOT£: FOR PERMITTED WORK WITHIN TH£ BUFFER, SE£ APPROVED BUFFER MIT/GA TION/tNHANC£M£NT PLAN. NOT£: CATCH BASINS HA VE 8££N SIZED TO MEET CURRENT KING COUNTY AND WSDOT KNOCKOUT R£QU/R£M£NTS USING ADS N-12 PIP£. CONTRACTOR MAY WORK DIR£CTl. Y WITH CATCH BASIN MANUFACTURER TO REDUCE CATCH BASIN SIZES PROVIDED KNOCKOUT REQUIREMENTS AR£ STILL MET. SA WCUT AT EXISTING FOGUN£ TO PROVIDE A CLEAN, VERTICAL EDGE FOR JOINING TO TH£ NEW ASPHALT. SEAL NEW JOINT AND OVERLAY STREET ON£ INCH, PLUS A PR£ LEVEL COURSE. TH£ REQUIREMENT FOR OVERLAY MAY 8£ WAIVED BY TH£ £NGIN££R OR REVIEWING AGENCY BASED Of,./ TH£ CONDITION OF EXISTING PA VEM£NT AND TH£ EXTENT OF REQUIRED CHANGES TO CHANNELIZATION P£'R KCRS 4.01.F.1. COORDINA T£ WITH INSPECTOR DURING CONSTRUCT/ON. JAMES H. SANDERS, P.E. DEVELOPMENT ENGINEER Comments: Approval Dote © 2008 TRIAD ASSOCIATES . '-'--•-'--'---'--'----'~-· ---= . ; ASSOCIATES s..------- 12112115thAve. NE Kirkland, WA 98034-6923 425.821.8448 425.821.3481 fax 800.488.0756 loll free www.triadassociates.net . ' laud Development Consultc1nts ~ ::e: 0 ~ ~ .. ., a.; (/) ~ .... ~ 0 ;§ ~ re .... 0 ~ ~ " :s: i ~ ::e: E .... ~E (/) ~ 'I:( C\ 'I:( Q: 0 Q:: ..... (/) ·~ Llj G£RALD F. BUCK, AICP PROJECT MANAGER NICK A. )INGER, PLS PROJECT SURVEYOR SHERI H. MURATA. PE: PROJECT ENGINEER JEFFREY L COJ<; ASLA PROJECT LANDSCAPE ARCHITECT FIRST SUBMITTAL DATE: B/20/07 SCALE: HORIZ.: 1"=40' l'ER'l'.:N/A K.C. D.D.F.S. Lo8'V oo 3'7 STAMP NOT VALID UNLESS SIGNED AND DATED JOB NO. 01-047 SHEET NO. 8or21 ' ~ ~ ~ &i ~ ).." .... ~ C) 0 ~ ~ ~ J I ,J I I , I i I I I 'v • I I I I I I I \ i I ' \ I I I I I I I I I I I I I I \ I \ .. I I I I I \ I I \ ---··- POR OF THE NE 1/ 4 OF THE SE 1/ 4 & THE SE 1/ 4 OF THE NE 1/ 4, ALL IN SEC. 10, TWP. 23 N., RGE. 5 E., W.M. / J, " t ! ·'·''->~--~" ',, _.,,.,,~c,_, ~ .. ,., __ ., INT 4+98.16 SE 119TH STREET -26+22.59 146TH AVENUE SE CB 19 25+84.69, 15'-12" 25+69.69 14.22' LT INSTALL END CAP WITH PHI CONSTRUCTION, TO BE REMOVED DURING PH2 CONSTRUCT/ON. -"·•-'"•"•~ -·-·--··-~ --__ " ------~64!18-, CB.24 ---···-, •. /4'1-58.03, 14.22 LT ,-'<lH~'r 53 : I ,i. fJ 19A •• ~ 5+82.47, 14,2 RT , 1 ·6·Tfl A VE i __ PROflLI;;' SHE£ CB JO 16+31.74, 14.22 RT 10'-12· 16+41.74 14.22' RT INSTALL END CAP WITH PHI CONSTRUCTION, TO BE REMOVED DURING PH2 CONSTRUCTION. ---~ "·· --~---~~--~~-~ CB JOA PCR=16+36.64 !,=8'5'36" R=35.75' 16+36.64 14.00' LT FLOltl.lNE END VERTICAL CURB. TRANSITION TO ROLLED CURB PER DETAIL, SHEET 17 "'"'""'""""'" i J -- I SCALE: 1" = 40' 0 20 40 80 ~ -- BE 120TH BT KEY MAP NOT TO SCALE aEANOUT SCHEDULE LOT# I 2 J 4 5 6 7 8 27 28 52 53 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 TOP (MATCH FG) 494.4 480.7 476.9 472.6 467.3 462.2 458.1 462.6 461.8 472.7 498.5 482.7 489.0 478,7 474.2 470.0 466.2 462.9 461.6 459.0 458.0 458.1 458.0 457.0 457,1 457.8 459.0 462.5 456.5 460.5 464.5 468.5 471.5 474.5 475.5 485.2 486.2 490.2 SIZE AND INVERT 5• IE 490.5 6" IE 475.9 6" IE 471.6 6" IE 466.3 a• IE 460.9 a• IE 456.5 8" IE 454.5 8" IE 453.8 6" IE 458.1 6" IE 468.7 6" IE 495.0 6" IE 479.7 8" IE 485.9 6" IE 474.7 6" IE 470.2 6" IE 466.2 6" IE 462.8 8" IE 459.5 B" IE 457.1 6" IE 455.5 6" IE 454.5 6" IE 453.9 6" IE 442.5 6" IE 452.4 6" IE 452.5 6" IE 454.0 6" IE 454.5 8" IE 451.0 8" IE 452.5 8" IE 455.2 a• IE 459.2 8" IE 463.2 6" IE 467.5 6" IE 470.5 6" IE 471,5 8" IE 480.5 6" IE 483.0 6" IE 487.0 FRAME AND GRATE LEGEND SHEET 14 FOR ROLLED CURB FRAME AND VANED GRATE STANDARD FRAME AND VANED GRATE STANDARD FRAME AND SOLID LOCKING LID TH A~ SE FRONTAGE I. 'PROVEMENTS. ALL CATCH BASINS ARE TYPE 1 UNLESS OTHERWISE NOTED. TMH . CULVERT NOTE: CATCH BASINS HA VE' BEEN SIZED TO MEET CURRENT KING COUNTY AND WSDOT KNOCKOUT REQUIREMENTS USING ADS N-12 PIPE. CONTRACTOR MAY WORK DIRECTLY WITH CATCH BASIN MANUFACTURER TO REDUCE CATCH BASIN SIZES PROVIDED KNOCKOUT REQUIREMENTS ARE STILL MET. ALL STORM DRAIN PIPE SHALL CONFORM TO SECTION 7.03 OF THE 1993 KING COUNTY ROAD STANDARDS. THE FOLLOWING PIPES, SPECIFIED IN SECTION 9-05 OF THE WSDOT/APWA STANDARD SPECIF/CATIONS ARE ALLOWED: PLAIN AND REINFORCED CONCRETE STORM SEWER PIPE. DUCTILE IRON, POLYVINYL CHLORIDE (PVC), LINED CORRUGATED POLYETHYLENE (LCPE), AND SOLID WALL POLYETHYLENE (SWPE) PIPE. 1 Q2" IE CMP 499.29 I I I I / !1t!Ti 1+00.00 SE 119TH STREET 1 I 3+94.15 148TH AVENUE SE £1 I CULVERT CAU710N LOCATION OF EXISTING UTILITIES SHOWN IS APPROX/MA TE AND MAY NOT BE ACCURATE OR ALL INCLUSIVE. IT IS THE CONTRACTOR'S RESPONSIBILITY TO FIELD VE'RIFY LOCATION OF UTILITIES PRIOR TO PROCEEDING WITH EX. CULVERT CONSTRUCTION. YOU MUST CALL 1-800-424-5555 12" IE CONG 501.95 NOT LESS THAN 2 FULL BUSINESS DAYS BEFORE BEGINNING EXCAVATION WHERE ANY UNDERGROUND UTILITIES MAY BE LOCATED. FAILURE TO DO SO COULD MEAN BEARING SUBSTANTIAL REPAIR COSTS. PROVIDE FALL PROTECTION FENCING AT TOP OF ANY WALL/r?OCKERY TALLER THAN 30• THERE SHALL BE NO DIRECT VE'HICULAR ACCESS TO OR FROM 148TH A VE' SE FROM THE LOTS WHICH ABUT THIS STREET KING COUNTY D.D.E.S. Review Engineer Senior Engineer JAMES H, SANDERS. P.E. DEVELOPMENT ENGINEER Comments: Completion Dote Completron Date Approval Date © 2008 TRIAD ASSOCIATES \. T -,· J J . - ASSOCIATES 12112 115th Ave. NE Kirkland, WA 98034-6923 425.821.8448 425.821.3481 fax 800.488.0756 toll free www.triadassociates.net • • Land Develo'pment Co11sultci11ts • • :c: ,q; ~ ~ ~ .... ~ (/) ~ ,q; C:\ ~ tt: GERALD F. BUCK, AICP PROJECT MANAGER NICK A. YINGER, PLS PROJECT SURVEYOR SHERI H. MURATA, PE PROJECT ENGINEER .EFFREY L cox; ASLA PROJECT LANDSCAPE ARCHITECT FIRST SUBMl'ITAL DATE: 8/20/07 SCALE: HOim.: 1"-40' VIRT.:N/A STAMP NOT VALID UNLESS SIGNED AND DATED 10B NO. 01-047 SHEET NO. 9oF21