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HomeMy WebLinkAboutMiscD.R. STRONG CONSULTING ENGINEERS TECHNICAL INFORMATION REPORT for ALPINE NURSERY Preliminary Plat 16023 SE 144'" Street and 14609/14625 161'' Avenue SE Renton, WA DRS Project No. 14069 Renton File No. Owner/Applicant Roy Boyer 14609 161 51 Ave SE Seattle, WA 98103 Report Prepared by llfilt§IJ D.R. STRONG Consulting Engineers, Inc. 620 ?1h Avenue Kirkland WA 98033 (425) 827-3063 ©2015 D.R. STRONG Consulting Engineers Inc. Report Issue Date January 12, 2015 RECE\VED JAN 1 4 ?.G15 CITY Of RENTON PLANNING DIVISION TECHNICAL INFORMATION REPORT ALPINE NURSERY PRELIMINARY PLAT TABLE OF CONTENTS SECTION I ...................................................................................................................... 1 Project Overview ......................................................................................................... 1 Predeveloped Site Conditions ..................................................................................... 1 Developed Site Conditions .......................................................................................... 2 Natural Drainage System Functions ............................................................................ 3 SECTION II ................................................................................................................... 11 Conditions and Requirements Summary ................................................................... 11 SECTION Ill .................................................................................................................. 13 Off-Site Analysis ........................................................................................................ 13 SECTION IV .................................................................................................................. 14 Flow Control and Water Quality Facility Analysis and Design ................................... 14 Existing Site Hydrology (Part A) ............................................................................. 14 Pre-developed Hourly Time Step Modeling Input: .................................................. 15 Pre-developed Hourly Time Step Modeling Output: ............................................... 15 Developed Site Area Hydrology (B) ....................................................................... 18 Developed Site Area Hydrology ............................................................................. 18 Developed Hourly Time Step Modeling Input: ........................................................ 19 Developed Hourly Time Step Modeling Output: ..................................................... 19 Bypass Hourly Time Step Modeling Input: ............................................................. 20 Bypass Hourly Time Step Modeling Output: ........................................................... 20 Performance Standards (Part C) ............................................................................... 22 Flow Control System (Part D) .................................................................................... 22 Flow Control BMP Selection ................................................................................... 23 Flow Control Facility Design Output ....................................................................... 24 Water Quality Treatment System (Part E) ................................................................. 27 SECTION V ................................................................................................................... 29 Conveyance System Analysis and Design ................................................................ 29 SECTION VI .................................................................................................................. 31 Special Reports and Studies ..................................................................................... 31 ©2015 D.R. STRONG Consulting Engineers Inc. Technical Information Report Alpine Nursery Page i of ii City of Renton SECTION VII ................................................................................................................. 32 Other Permits, Variances and Adjustments ............................................................... 32 SECTION VIII ................................................................................................................ 33 ESC Plan Analysis and Design (Part A) .................................................................... 33 SWPPS Plan Design (Part B) .................................................................................... 34 SECTION IX .................................................................................................................. 35 Bond Quantities, Facility Summaries, and Declaration of Covenant. ......................... 35 Stormwater Facility Summary Sheet. ......................................................................... 36 SECTION X ................................................................................................................... 38 Operations and Maintenance Manual ........................................................................ 38 APPENDIX A ................................................................................................................ 39 Offsite Analysis .......................................................................................................... 39 List of Figures Figure 1 Tl R Worksheet .................................................................................................. 4 Figure 2 Vicinity Map ....................................................................................................... 7 Figure 3 Drainage Basins, Subbasins, and Site Characteristics ..................................... 8 Figure 4 Soils .................................................................................................................. 9 Figure 5 Predevelopment Area Map .............................................................................. 15 Figure 6 Post Development Area Map .......................................................................... 20 Figure 7 Detention & Water Quality Facility Details ....................................................... 27 ©2015 D.R. STRONG Consulting Engineers Inc. Technical Information Report Alpine Nursery Page ii of ii City of Renton SECTION I PROJECT OVERVIEW The Project is the subdivision of three existing parcels zoned R4 (9.64 ac. total) into 27 single-family residential lots, per the City of Renton's (City) subdivision process. The Tax Parcel Numbers are 232305-9044, -9099, and -9167. The Project (Site) is located at 16023 SE 144th Street and 14609/14625 161 51 Avenue SE Renton, Washington. The Project will meet the drainage requirements of the 2009 King County Surface Water Design Manual (Manual), as adopted by the City. PREDEVELOPED SITE CONDITIONS Total existing Site area is approximately 419,829 s.f. (9.64 ac). Total proposed Project area is 435,880 s.f. (10.0 ac). This includes Tract C, a tree retention tract, which will remain undisturbed and not be considered in final drainage calculations (0.73 acres, total developable area will be 9.27 acres). The Site contains two single family residences with associated driveways. The Site also includes a plant nursery with associated green houses and driveways. The remainder of the site is bramble, pasture and an area of trees on the southern parcels. The Site contains two Threshold Discharge Areas (TOA), TOA North and TOA South. TOA North includes the northeast corner of the Project and the associated frontage around the corner of SE 144th Street and 161 51 Avenue SE. Runoff from approximately 18,929 s.f. (0.43 acres) sheet flows to the north into a catch basin on the south side of SE 1441h Street. Runoff continues west through the conveyance system for approximately 0.25 miles to the intersection with 155th Avenue SE. Runoff continues west in the dirt road west of SE 1441h Street and then crosses underneath 154th Place SE where it outlets to Stewart Creek, a Class 3 stream. Stewart Creek outlets to Cedar River approximately 0.4 miles west of the Site. TOA South is approximately 9.57 acres in size (8.84 acres excluding tree retention area). Runoff sheet flows across the south property line and onto adjacent properties. Runoff continues south as sheet flow across adjacent properties to the south before it enters the conveyance system in the cul-de-sac of 1601h Place SE which outlets to the ditch at the northeast corner of SE 1481h Street and 1601h Place SE. Flow enters a Type 2 catch basin east of the intersection approximately 100' and follows the conveyance system west in SE 1481h Street and then south in 1601h Place SE. At the corner of SE 1491h Street and 1601h Place SE runoff is directed southwest through a property and conveyed down the hillside through an 18" HOPE pipe. Flow continues south through the conveyance system in 1601h Place SE and eventually outlets to Cedar River. See Section Ill for more detail. Due to site conditions (grading) and required right-of-way improvements the predeveloped areas for both TDAs will be modified in the developed condition (See Section IV). For the purpose of hydrologic calculations, both TDAs will be modeled as outwash forest. There is also an upstream tributary area that enters the Site that is approximately 9,800 s.f. (0.225 ac). It is currently developed with a single family residence and associated gravel and paved driveways. This existing upstream area will be collected and ©2015 D.R. STRONG Consulting Engineers Inc. Technical Information Report Alpine Nursery Page 1 Ctty of Renton conveyed to the proposed infiltration facility in Tract "B". For the purpose of hydrologic calculations, the upstream tributary area will be modeled as existing conditions for both the predeveloped and developed conditions. DEVELOPED SITE CONDITIONS The applicant is seeking approval to create 27 lots with lot sizes ranging from approximately 8,000 s.f. to 13,369 s.f. All existing improvements located on the Site will be demolished or removed during plat construction. The Project is subject to Full Drainage Review and has two distinct TDAs as described in the previous section. Developed TDA South will be approximately 9.02 acres, excluding the tree retention tract, which makes TDA North is 11,009 s.f. (0.253 ac) in the developed condition. The frontage improvements within TDA North will create less than 10,000 s.f. of new impervious surface (5,641 s.f. total) and less than 5,000 s.f. of pollution generating impervious surface (2,068 s.f. total). TDA North will result in no more than a 0.1-cfs difference between the developed 100-year peak flow and the historic site conditions 100-year peak flow. Therefore, TDA North meets the criteria for Conservation Flow Control Area Exceptions and is exempt from Core Requirement #3 Flow Control. Additionally, TDA North is exempt from Core Requirement #8 Water Quality by meeting the criteria for the "Surface Area Exemption". See Section IV for detail. TDA South will consist of the remaining frontage improvements for the Project along with the 27 single-family residences. For purposes of hydrologic calculations, the tree retention tract will not be included in the following area calculations as it does not constitute a target surface as defined in the Manual. The 27 single-family residences combined with their driveways will create approximately 98,065 s.f. (2.25 ac) of impervious area (this number includes the 50% credit taken for BMP's proposed on each lot, See Section IV). The proposed internal plat road will have a proposed 53-foot right of way and will be improved with 26 feet of pavement, vertical curb, gutter, 8-foot planter strip and 5-foot sidewalk. The improvements from the internal plat road along with the remaining frontage improvements will add approximately 123,177 s.f. (2.83 ac) of impervious surface. TDA South, including bypass area, will result in a total of 5.41 ac of new impervious surfaces. The remainder of the TDA South (3.61 ac) will consist of landscaping and lawns. As described above, the upstream tributary area will be modeled as existing conditions in the developed conditions. The upstream tributary area consists of 4,580 s.f. (0.105 ac) of impervious area and 5,220 s.f. (0.120 ac) of lawn. The Project is required to provide Flow Control Duration Standard, Forested Site Conditions and Basic Water Quality treatment, per the Manual. All surface water runoff from impervious surfaces except from the bypass areas will be collected and conveyed to an infiltration pond located in Tract "B"; the pond is designed to infiltrate the 100-year storm event and will limit the discharge to emergency overflow situations only. Prior to entering the pond, runoff will be routed through a StormFilter vault to accommodate Water Quality requirements. The bypass area of 4,009 s.f., in the southernmost part of 160 1h Ave SE along the west property line (160 1h Bypass Area), will be directed to a drywell in the southwest corner to be fully infiltrated. The bypass area of 1, 11 O s.f. at ©2015 D.R. STRONG Consulting Engineers Inc. Technical Information Report Alpine Nursery Page 2 City of Renton the southeast corner of the Project (161 51 Bypass Area) will flow south into the rroposed conveyance system and connect to the existing conveyance system in SE 1481 Street. NATURAL DRAINAGE SYSTEM FUNCTIONS Runoff generally flows south and southwest as sheet flow across the Site. The northeast portion of the Project including the frontage along the intersection of SE 144th Street and 161 51 Avenue SE, approximately 18,929 s.f., sheet flows northwest off the Site and into a catch basin on the south side of SE 1441h Street. The vegetation consists of pasture, underbrush and scattered trees. Site runoff travels as sheet flow over the western half of the south property line onto neighboring properties. A review of the SCS soils map for the area (see Figure 4, Soils) indicates Everett gravelly sandy loam with O to 5 percent slopes (EvB). Per the Manual, this soil type is classified as "Outwash" material. The SCS Soil series descriptions follow Figure 4. In evaluating the upstream area, we reviewed King County iMAP aerial topography, City of Renton Mapping Application and conducted field reconnaissance to evaluate conditions and potential problems. There is small portion of upstream tributary runoff entering the Site. It will be collected and conveyed to the proposed infiltration pond. ©2015 D.R. STRONG Consulting Engineers Inc. Technical Information Report Alpine Nursery Page 3 City of Renton FIGURE 1 TIR WORKSHEET King County Department of Development and Environmental Services TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 1 PROJECT OWNER AND PROJECT ENGINEER Project Owner: Roy Boyer Address/Phone: 14609 151•1 Avenue SE Renton, WA 98059 Project Engineer: Maher A. Joudi, P.E. Part 2 PROJECT LOCATION AND DESCRIPTION Project Name: Alpine Nursery Location: Township: Range: Section: 23 North 05 East 23 D. R. STRONG Consulting Engineers Inc. Address/Phone: 620 ih Avenue Kirkland WA 98033 (425) 827-3063 Part 3 TYPE OF PERMIT Part 4 OTHER REVIEWS AND PERMITS APPLICATION ~ Subdivision LJ DFWHPA LJ Shoreline D Short Subdivision ~ Clearing and Grading D Commercial D other: Management 0 COE404 D Rockery D DOE Dam Safety D Structural Vault D FEMA Floodplain D other: D COE Wetlands Part 5 SITE COMMUNITY AND DRAINAGE BASIN Community: Newcastle Drainage Basin Lower Cedar River ©2015 D.R. STRONG Consulting Engineers Inc. Technical Information Report Alpine Nursery Page4 City of Renton Part 6 SITE CHARACTERISTICS LJRiver: D Floodplain D Wetland D Stream: D Seeps/Springs D Critical Stream Reach D High Groundwater Table D Depressions/Swales D Groundwater Recharge D Lake: D Other: D Steep Slopes Part 7 SOILS Soil Type: Slopes: Erosion Potential: Erosive Velocities: Everett (EvB) 0-5% Slight Slow [giAdditional Sheets Attached: SCS Map and Soil Description, Figure 4 Part 8 DEVELOPMENT LIMITATIONS REFERENCE LIMITATION/SITE CONSTRAINT [gJ Level 1 Downstream Analysis None _____________ _ [gJ Geotechnical Engineering Study D Environmentally Sensitive Areas D Level 2 Off-Site Stormwater Analysis [gJ Level I Traffic Impact Analysis D Structural Report D Additional Sheets Attached Part 9 ESC REQUIREMENTS MINIMUM ESC REQUIREMENTS DURING CONSTRUCTION [g!Sedimentation Facilities [g!Stabilized Construction Entrance [g!Perimeter Runoff Control [g!Clearing and Grading Restrictions [gicover Practices [g!Construction Sequence D Other ©2015 D.R. STRONG Consulting Engineers Inc. Technical Information Report MINIMUM ESC REQUIREMENTS AFTER CONSTRUCTION [g!Stabilize Exposed Surface [giRemove and Restore Temporary ESC Facilities [giClean and Remove All Silt and Debris [g!Ensure Operation of Permanent Facilities DFlag Limits of SAO and open space preservation areas D Other Alpine Nursery Page 5 City of Renton Part 10 SURFACE WATER SYSTEM LJ Grass Lined Channel [2J Pipe System 0 Open Channel 0 Dry Pond 0 Wet Pond 0 Tank 0 Vault 0 Energy Dissipater 0 Wetland D Stream ~ Infiltration Pond 0 Depression 0 Flow Dispersal 0 Waiver 0 Regional Detention Method of Analysis: KCRTS Compensation/ Mitigation of Eliminated Site Storage NIA Brief Description of System Operation: Runoff from impervious surfaces will be collected and conveyed to the infiltration facility. An emergency overflow is provided to connect to the proposed conveyance system in 1s1•1 Avenue SE before discharging into the existing conveyance system in SE 1481h Street. Facility Related Site Limitations: Reference Facility Limitation Part 11 STRUCTURAL ANALYSIS ~ D D D Cast in Place Vault Retaining Wall Rockery > 4' High Structural on Steep Slope Other: Part 12 EASEMENTS/TRACTS ~ Drainage Easement 0 Access Easement 0 Native Growth Protection Easement [2J Tracts [2J Other: Temp. Turnaround Easement Part 13 SIGNATURE OF PROFESSIONAL ENGINEER I or a civil engineer under 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 in mation provided here is accurate. ©2015 D.R. STRONG Consulting Engineers Inc. Technical Information Report Alpine Nursery Page6 City of Renton The informat ion included on this map has been comp iled by King County staff from a variety of sources and is subject to change without notice. King County makes no representat io ns or warranties , express or implied , as to accuracy, co mpleteness. timeliness, or rights to the use of such information. King County shall not be liable for any general, special , ind irect , incidental, or consequential damages including , but not l imited to, l ost revenues or l os t profits resulting from t he use or misuse of the informati on contained on this map. Any sale of th is map or information on th is map is p roh ibited except by wri tte n permission of King County. ©2015 D . R . STRONG Consulting Engineers Inc. Technical Informat ion Report A lp ine Nursery Page 7 City of Renton FIGURE 3 DRAINAGE BASINS, SUBBASINS, AND SITE CHARACTERISTICS ©2015 D.R. STRONG Consulting Engineers Inc. Technical Information Report Alpine Nursery Page 8 City of Renton I I ' I ' I I j ,Jc '. / I ,-------1:l\.'. J J I : ·--1 -----l ,·-} \ (,{ ;.,< J>' " ..c' _{' ,, I ' ' I I I ' '. j . -'i· .. ··.' " ' 1 .. ·' ·.···.· .i' I I I ,· I II I ~1-~._j1. , .!-;_~ ·:Js,q1. n~("'"'"''~)--_ J I ~ ---~ ---i ! r --• , .. ·.,, -.. -...•. -.. "·.· . . ::,,.;;· ... . . , .. 1 ' . I ' -J r ' ----..-· x "-. • . ... . . '>-. •. ,,,, I -I 1 1· --·-l''"'' TOA·,\,.. . , ·~·. '· ·--,,·,, ' ' ' ' ' -' ,, ' ' ' ---;;{NOFF I J'/ '.i ';;1':,dt'm ~.;,:'?::cc-, : I ,ij \ [i ,' J I J f1/7rlj'f~1i~c~~ '\. t .. : · ... t2' '/\ -~~.--. "-c' _ \ \ ·.--···· ~-::,,...-~---.· ---_f' ';;, < .... ,C;;;:iC:,CC'fr;·c;:,oe::;cC,J;;<f!'', ',,;;,~,·;.',· I _•n,.s=~j 'I' , ., > ":j ,, ,· "':,. ... . . ·" .,,,.,,,.,.' ,, ·."'" '-_;, -_.,.. _.,,.. -i .: . t'-. 1. >f#.,,:'til _:· .-.. 1. f ""! ,. 'ii < --:;.<• ;;,,; ,,;:: -:-,. ""·~ ; ' ' ' _i _;; --_,.- I .. ' / , ' 'O ' ' '' • ' ' _l -. ; ~ ;-_ ·_ iv i .· ;~ 1 \ \f. . , · ":, .' ' i'i. ; -'-' . ---1 "" .. ~.y. ', ' ' 'J, ' ' ,,, '. . ,,,, I I ~ ,, ~·1 ; -t . . '., '''''"'-! . /• . 'Ill ' ' "". .--. '~ ~-<,/(· I r l'Y , i r~·''·""'·----;::, , t,u;:J~T"~,;,'.\~ I r 1:. lfZ 1r--'::::-, ·. I t'>t; r , t; j I if i U~1L:;1[;·; .. ,0 ft .. =·''.:::/ '; . y ___ ) ? J'J /:-·--··--·"· '-~--"~,) -· ---, L,, t_ "-----:,~~~'.;-'; £?::·L2~· _---} \~ 4· _.,,,,.._ , <:.-.. 1 -}\' ;)'' ..:__, ' t~ f, ' ----: ~ / ~-;· . ' I :J, • -, --r. :-\X ,, (: ~"--.,' ·, .. Ji -:---'/' 11 ' ::{!.· Jc,' J ·. ·. :::::::\ ; , I .r, --' ::--..i :,;.> ; I r ·. ·-. .---: ---' i ·_ ;> ~ - ·····.J--;> "{; 1 • ,' J '\ ,. ::----, :-----» ' ~ ~- ~ ---.._ ·, --..,,,.,. :-:';N--. · .:__ i~----->,·" ; ii' " 1, . I I I I ---JI / RUNOFF DISfiiARGES- AS SHEET fl-OW ACROSS S04/TH PROPERTY 'NE ___ LI_ I "' I y-~ ( ---- -~·- /~I- I I T'. <. ·-·-·-n. . ,, I ~ K_----.... --/~ -~ r>~·:, ·· 1-:a~~v:;E , --"""'". _ -· =--== ·i-I , 1 r : ~T ·--i'..~·tf,~~·-,·~. ,{4/,'t·;::~.,.:· -~-I ~---L_ ,, 1,,, ,,,, J,;; r'", I';;_' rt i:t ·nt. ~? tt~ .~ t1, .. \ \ ! r LEGEND ---PROJECT BOUNDARY @ • • • • • • TOA BOUNDARY NORTH GRAPHIC SCALE SITE BOUNDARY 0 50 100 150 g UPSTREAM TRIBUTARY AREA 1 INCH= 100 FT. R:\2014\0\14069\3\Drow!ngs\Plots\PP\Report Flgures\FIGJ BASIN 14069.dwg 1/12/2015 8:14:50 AM PST COPYRIGHT@ 2015_,. D.R. STRONG CONSULTING ENGINEERS INC. I I~ ! 1 l ~ I ! Ii M»III I:; ~ ~ ~ ~ r::: ~ ~ ). ~~ !'fi, ~ ((j ~ !,&j ~ ::! as i..;;; !:i:~~ 0 :::s 15 "" ~ ~ ::! ~- II:: ;!: "II f? i ~!;;; u i!: ~ ! ri5 ~ ~ ~ .... ORAFTED BY.· CEN DESIGNED BY: PROJECr ENGINEER: MAJ OA TE: 01.06.15 PROJ£CT NO.: 14Q69 F1GURE: 3 I FIGURE 4 SOILS ----====-------=======-0 ~ ~ ~ ~ --==----=====rttt 0 50 ~ 200 XX> ~~: -~ Can:r~ >\GS84 fdQo= llll1Zme ICYI V,GS&I l&O\ N3ti.nl R~ iiilllii ConH<V.otion s..v;~ ©2015 D.R . STRONG Consu lt ing Engineers Inc. Technical Information Report WebSoil~ N~tion.1! Cooperative Soil Survey A lpine Nursery t, 12/15/2014 P.:,ge 1 ol 3 Page 9 City of Renton EvB-Everett gravelly sandy loam, 0 to 5 percent slopes Map Unit Setting • National map unit symbol: 1 hmt2 • Mean annual precipitation: 30 to 45 inches • Mean annual air temperature: 50 degrees F • Frost-free period: 180 days • Farmland classification: Prime farmland if irrigated Map Unit Composition • Everett and similar soils: 100 percent • Estimates are based on observations, descriptions, and transects of the mapunit. Description of Everett Setting • Landform: Terraces • Parent material: Glacial outwash with a component of volcanic ash in the upper part Typical profile • H1 -0 to 17 inches: gravelly ashy sandy loam • H2 -17 to 32 inches: very gravelly sandy loam • H3 -32 to 60 inches: very gravelly coarse sand Properties and qualities • Slope: O to 5 percent • Depth to restrictive feature: More than 80 inches • Natural drainage class: Somewhat excessively drained • Capacity of the most limiting layer to transmit water (Ksat): High (1.98 to 5.95 in/hr) • Depth to water table: More than 80 inches • Frequency of flooding: None • Frequency of ponding: None • Available water storage in profile: Low (about 5.0 inches) Interpretive groups • Land capability classification (irrigated): None specified • Land capability classification (nonirrigated): 3s • Hydrologic Soil Group: A • Other vegetative classification: Draughty Soils (G002XN402WA) ©2015 D.R. STRONG Consulting Engineers Inc. Technical Information Report Alpine Nursery Page 10 City of Renton SECTION II CONDITIONS AND REQUIREMENTS SUMMARY The Project must comply with the following Core and Special Requirements: • C.R. #1 -Discharge at the Natural Location: TDAs North and South will discharge at their natural location. TOA North will discharge into the existing conveyance system within SE 144th Street. Whereas, TOA South runoff discharges from the Site as sheet flow over the western half of the south property line. Developed Site runoff will discharge at the southeast corner into the proposed conveyance system flowing south along 161st Avenue SE and then west into the SE 148th Street conveyance system. The existing downstream path and proposed downstream path converge approximately 600' downstream and are within the same TOA. • C.R. #2 -Offsite Analysis: Analysis is included in Appendix A. The Analysis describes the Site's runoff patterns in detail. • C.R. #3 -The Project is located in the Flow Control Duration Standard, Forested Site Conditions area. An infiltration pond will provide flow control as required. The Project is required to match durations for 50% of the two-year peak flow up to the full 50-year peak flow. Also match developed peak discharge rates to predeveloped peak discharge rates for the 2-year and 10-year return periods (KCSWDM, Sec. 1.2.) Furthermore, the Project must meet the Flow Control BMP requirements as specified in Section 1.2.3.3 of the Manual. The Project will utilize limited infiltration through drywells to mitigate for an impervious area equal to at least 10% of each lot area. See Section IV. • C.R. #4 -Conveyance System: New pipe systems and ditches/channels are required to be designed with 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. Pipe system structures and ditches/channels may overtop for runoff events that exceed the 25-year design capacity, provided the overflow from a 100-year runoff event does not create or aggravate a "severe flooding problem" or "severe erosion problem" as defined in C.R. #2. Any overflow occurring onsite for runoff events up to and including the 100- year event must discharge at the natural location for the project Site. In residential subdivisions, such overflow must be contained within an onsite drainage easement, tract. covenant or public right-of-way. The proposed conveyance system was analyzed using the KCBW program, and is capable of conveying the 100-year peak storm without overtopping any structures or channels. This analysis will be performed at time of construction plan preparation. • C.R. #5 -Erosion and Sediment Control: The Project provides the nine minimum ESC measures. • C.R. #6 -Maintenance and Operations: Maintenance of the proposed storm drainage facilities will be the responsibility of the City. An Operation and ©2015 D.R. STRONG Consulting Engineers Inc. Technical Information Report Alpine Nursery Page 11 City of Renton Maintenance Manual will be included in Section X at the time of construction plan preparation. • C.R. #7 -Financial Guarantees: Prior to commencing construction, the Applicant must post a drainage facilities restoration and Site stabilization financial guarantee. For any constructed or modified drainage facilities to be maintained and operated by the City, the Applicant must: 1) Post a drainage defect and maintenance financial guarantee for a period of two years, and 2) Maintain the drainage facilities during the two-year period following posting of the drainage defect and maintenance financial guarantee. • C.R. #8 -The Project is located in the Basic Water Quality Treatment area. The Project will utilize an infiltration facility and is therefore required to provide water quality prior to infiltration. A StormFilter will accommodate this requirement. • S.R. #1 -Other Adopted Area-Specific Requirements: Not applicable for this Project. • S.R. #2 -Floodplain/Floodway Delineation: Not applicable for this Project. • S.R. #3 -Flood Protection Facilities: Not applicable for this Project. • S.R. #4 -Source Control: Not applicable for this Project. ©2015 D. R. STRONG Consulting Engineers Inc. Technical Information Report Alpine Nursery Page 12 City of Renton SECTION Ill OFF-SITE ANALYSIS An Offsite Level One Downstream Analysis was prepared by D.R. STRONG Consulting Engineers Inc. and is included in Appendix A. ©2015 D.R. STRONG Consulting Engineers Inc. Technical Information Report Alpine Nursery Page 13 Cny of Renton SECTION IV FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN EXISTING SITE HYDROLOGY (PART A) KCRTS was used to model the peak runoff from the Site. Per Table 3.2.2.b of the Manual the soil type is modeled as "Outwash" for the Everett gravelly sandy loam SCS classification as shown in Figure 4. Soils. The entire Site, with the exception of the upstream tributary area, is modeled as "Forest." Results of the KCRTS analysis are included in this section. Area Breakdown TDA North Outwash Forest TDA South Outwash Forest Upstream Tributary Area Impervious Till Grass 18,929 s.f. 384,968 s.f. 4,580 s.f. 5,220 s.f. 0.435 acres 8.838 acres 0.105 acres 0.120 acres For modeling purposes, the upstream tributary area was combined with TOA South for analysis. ©2015 D. R. STRONG Consulting Engineers Inc. Technical Information Report Alpine Nursery Page 14 City of Renton TOA NORTH PRE-DEVELOPED HOURLY TIME STEP MODELING INPUT: Land cover Till Forest (ac) 0.000 Till Grass (ac) 0.000 Outwash Forest (ac) 0.435 Impervious (ac) 0.000 Scale Factor: 1.00 Time Step: Hourly Data Type: Reduced Project location: Seatac Total Area: • 0.435 PRE-DEVELOPED HOURLY TIME STEP MODELING OUTPUT: Flow Frequency Analysis Time Series File:predev.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--------Flow Frequency Analysis------- Flow Rate Rank Time of Peak --Peaks Rank Return (CFS) (CFS) Period 0.000 2 10/09/00 23:00 0.001 1 100.00 0.000 3 11/19/01 4:00 0.000 2 25.00 0.000 4 11/03/02 18:00 0.000 3 10.00 0.000 5 2/10/04 8:00 0.000 4 5.00 0.000 6 11/16/04 6:00 0.000 5 3.00 0.000 7 10/27/05 12:00 0.000 6 2.00 0.000 8 10/26/06 15:00 0.000 7 1.30 0.001 1 1/09/08 3:00 0.000 8 1.10 Computed Peaks 0.001 50.00 TOA SOUTH PRE-DEVELOPED HOURLY TIME STEP MODELING INPUT: Land cover Till Forest (ac) Till Grass (ac) Outwash Forest (ac) Impervious (ac) Scale Factor: Time Step: Data Type: Project location: Total Area: .. 0.000 0.120 8.838 0.105 1.00 Hourly Reduced Seatac 9.063 ©2015 D.R. STRONG Consulting Engineers Inc. Technical Information Report Alpine Nursery Prob 0.990 0. 960 0.900 0.800 0.667 0.500 0.231 0.091 0.980 Page 15 City of Renton TDA SOUTH PRE-DEVELOPED HOURLY TIME STEP MODELING OUTPUT: Flow Frequency Analysis Time Series File:predev.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- Flow Rate Rank Time of Peak (CFS) 0.038 5 2/09/01 2:00 0.028 8 1/05/02 16:00 0.044 2 2/27/03 7:00 0.029 7 8/2 6/04 2:00 0.036 6 10/28/04 16:00 0.038 4 1/18/06 16:00 0.042 3 10/26/06 0:00 0.079 1 1/09/08 6:00 Computed Peaks ©2015 D.R. STRONG Consulting Engineers Inc. Technical Information Report -----Flow Frequency Analysis------- --Peaks Rank (CFS) 0.079 1 0.044 2 0.042 3 0.038 4 0.038 5 0.036 6 0. 029 7 0.028 8 0. 067 Alpine Nursery Return Period 100.00 25.00 10.00 5.00 3.00 2.00 l. 30 1.10 50.00 Prob 0.990 0. 960 0.900 0.800 0.667 0.500 0.231 0.091 0.980 Page 16 City of Renton FIGURE 5 PREDEVELOPMENT AREA MAP ©2015 D.R. STRONG Consulting Engineers Inc. Technical Information Report Alpine Nursery Page 17 City of Renton / , -! I , )f -·-· ,./·, ·~ . 11 -----, -·-·. J' 1/'.Ji·· " ~ I . ·'-)f I 1~ ·•· __j -; I ,'/'I'' I r lJJ I I I I,, i 1:.: ,!;1' ,I, i!V ~I . \:'Vi ):.,i;~:f· ..-,'. }i1\ ·--- I -I ' '1 I L 1:1 ::1 .. ')Ji, ·-· :-4,:~1~,Z;j.,) I I I ~---t-----J L ---J I I I ,' I .. j I / , I ' r'. J' -!t!!, I /~, -: : ; ,: , . ,.} . I ' "''. I I '··1 I ' " -:--,: -· "-.. 1;~~..: ~s \ ... ,i,. --~·,c:.s::-.:- ~~·?> '--1..... }. 1li1 ,,,;~·s-r'".kw~z.rs,e··~,·, . ~--,-·--/~,.~~ J6f_ --· ;:sp!!,;_ ':-:-:-:-;y.:~-:,~-:~~\h.:,:,:~~ ... :-:.:.,;.:.;.:~ :-.-................ .. mt:·:,. :~:.: ........ ·: -~.:':: 1f;OTHAVESE · • -· T~--·-·--;, I -· --·-·-·-·,-i! L'_ -- AREA BREAKDOWN TOTAL SITE: AREA: TOTAL PROJECT AREA: TOTAL DEVELOPABLE AREA: TOA SOUTH AREA: 419,829 SF. (9.64 ACRES) 435,880 S.F. (10. 0 ACRES) 403,897 S.F. (9.27 ACRES} 384,968 S.F. (8.84 ACRES} TOA NORTH AREA: 18,929 S.F. (0.43 ACRES} UPSTREAM TRIBUTARY AREA TOTAL PARCEL AREA: IMPERVIOUS AREA: PERVIOUS AREA (TILL GRASS}: 9,800 S.F. (0.225 ACRES) 4,580 S.F. (0.105 ACRES) 5,220 S.F. (0.120 ACRES) LEGEND ---PROJECT BOUNDARY • • • • • • TOA BOUNDARY ~ ~ [G7] L8J TOA SOUTH TOA NORTH UPSTREAM TRIBUTARY AREA R: \2014\0\14069\3\Drawfngs\Pfals\PP\Reporl Figures\FIGS PREDEV 14069.dwg 1/12/2015 8:22:03 AM PST I I I ·t 0 I -I I' , .1-1~ I; \· i! l!a -- ti~ <I• :;,: "' ,__ so: ,_,._ so:~ g,6 " ,e:'t>:: " C5 a.: .~ :<: " ;,,:_ i:!:!e ~ c:, :::, 111d e:: ~ / / / f' ~ ~ @ NORTH GRAPHIC SCALE 50 100 150 1 INCH= 100 FT. ; ~ I~ ' E o a 11 ll~JJ 11 ~ Q. ~ ; <( 1-, Cl) ~ <o ~ >-ii Q: 8:i 't ~ ~~~ @ ~~~ ~ ~;e ~ ~~; ~ ! 1.1,j ~ 9:: ~ a.: ~ .... DRAFTED BY: C£N DESIGNED BY: PRo.ECT ENGINffR: MAJ DATE:; 01.06.15 PROJECT NO.: 14069 FIGURE: 5 COPYRfGHT @2015, D.R. STRONG CONSULTING ENGlNEERS INC. I DEVELOPED SITE AREA HYDROLOGY (B) DEVELOPED SITE AREA HYDROLOGY KCRTS was used to model the developed peak runoff from the Site. The soil types are unchanged from the pre-developed conditions. However, all lawn and landscaping portions of the Site will be modeled as "Till Grass" rather than outwash to account for topsoil and landscaped conditions. Results of the KCRTS analysis are included in this section. Area Breakdown TDA North* Impervious Till Grass TDA South Impervious Till Grass Upstream Tributary Area Impervious Till Grass 5,641 s.f. 5,368 s.f. 231,256 s.f. 156,049 s.f. 4,580 s.f. 5,220 s.f. 0.130 acres 0.123 acres 5.309 acres 3.582 acres 0.105 acres 0. 120 acres 1601h Bypass Area {Routed to Drywell for Full Infiltration)** Impervious 3,093 s.f. 0.071 acres Till Grass 916 s.f. 0.021 acres 161 51 Bypass Area {161 51 Ave SE} Impervious 1,110 s.f. Till Grass 464 s.f. 0.025 acres 0.011 acres *Due to construction of frontage improvements, the developed TOA boundaries are different than the predeveloped. TOA South grows approximately 0.20 acres in the developed condition. The predeveloped boundaries were used to calculate allowable discharges, as to not increase or alter runoff going to each TOA. **A 10-foot by 10-foot by 2.5-foot deep drywell will be utilized to fully infiltrate the bypass area within 1601h Avenue SE. The drywell was sized based on 60 c.f. of gravel per 1,000 s.f. of impervious surface area. This is per Section C.2.2.4 of the Manual and soil logs per the Geotechnical Engineer. No KCRTS modelling was performed. ©2015 D.R. STRONG Consulting Engineers Inc. Technical Information Report Alpine Nursery Page 18 Ctty of Renton TDA NORTH DEVELOPED HOURLY TIME STEP MODELING INPUT: Land cover Till Forest (ac) 0.000 Till Grass (ac) 0.123 Outwash Forest (ac) 0.000 Impervious (ac) 0.130 Scale Factor: 1.00 Time Step: Hourty Data Type: Reduced Project location: ~ Seatac Total Area: 0.253 TDA NORTH DEVELOPED HOURLY TIME STEP MODELING OUTPUT: Flow Frequency Analysis Time Series File:dev.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--------Flow Frequency Analysis------- Flow Rate Rank Time of Peak --Peaks Rank Return (CFS I (CFS) Period 0.043 5 2/09/01 2:00 0.088 1 100.00 0.033 8 1/05/02 16:00 0.051 2 25.00 0.051 2 2/27/03 7:00 0.051 3 10.00 0.035 7 8/26/04 2:00 0.045 4 5.00 0.042 6 10/28/04 16:00 0.043 5 3.00 0.045 4 1/18/06 16:00 0.042 6 2.00 0.051 3 10/26/06 0:00 0.035 7 1. 30 0.088 1 1/09/08 6:00 0.033 8 1.10 Computed Peaks 0.076 50.00 TDA SOUTH DEVELOPED HOURLY TIME STEP MODELING INPUT: Land cover Till Forest (ac) 0.000 Till Grass (ac) 3.702 Outwash Forest (ac) 0.000 Impervious (ac) 5.414 Scale Factor: 1.00 Time Step: Hourty Data Type: Reduced Project location: Seatac ... Total Area: 9.116 ©2015 D.R. STRONG Consulting Engineers Inc. Technical Information Report Alpine Nursery Prob 0.990 0. 960 0.900 0.800 0.667 0.500 0.231 0.091 0.980 Page 19 City of Renton TDA SOUTH DEVELOPED HOURLY TIME STEP MODELING OUTPUT: Flow Frequency Analysis Time Series File:dev.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--------Flow Frequency Analysis------- Flow Rate Rank Time of Peak --Peaks (CFS) (CFS) 1. 64 6 2/09/01 2:00 3.34 1.32 8 1/05/02 16:00 2.06 1. 98 3 2/27 /03 7:00 1. 98 1. 42 7 8/2 6/04 2:00 1. 74 1. 71 5 10/28/04 16:00 1. 71 1. 74 4 1/18/06 16:00 1. 64 2.06 2 10/2 6/06 0:00 1. 42 3.34 1 1/09/08 6:00 1. 32 Computed Peaks 2.92 161 5 T BYPASS HOURLY TIME STEP MODELING INPUT: Land cover Till Forest (ac) 0.000 Till Grass (ac) 0.011 Outwash Forest (ac) 0.000 Impervious (ac) 0.025 Scale Factor: 1.00 Time Step: Hourly Data Type: Reduced Project location: Seatac .. Total Area: 0.036 161 5 T BYPASS HOURLY TIME STEP MODELING OUTPUT: Flow Frequency Analysis Time Series File:bypass(l6lst) .tsf Project Location:Sea-Tac 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 0.091 50.00 0.980 ---Annual Peak Flow Rates--------Flow Frequency Analysis------- Flow Rate Rank Time of Peak --Peaks Rank Return Prob (CFS) (CFS) Period 0.007 6 2/09/01 2:00 0. 014 1 100.00 0.990 0.006 8 1/05/02 16:00 0.009 2 25.00 0. 960 0.009 3 2/27/03 7:00 0.009 3 10.00 0.900 0.006 7 8/26/04 2:00 0.008 4 5.00 0.800 0.008 4 10/28/04 16:00 0.007 5 3.00 0.667 0.007 5 1/18/06 16:00 0.007 6 2.00 0.500 0.009 2 10/26/06 0:00 0.006 7 1. 30 0.231 0.014 1 1/09/08 6:00 0.006 8 1.10 0.091 Computed Peaks 0. 013 50.00 0.980 ©2015 D.R. STRONG Consulting Engineers Inc. Alpine Nursery Page 20 Technical Information Report City of Renton FIGURE 6 POST DEVELOPMENT AREA MAP ©2015 D. R. STRONG Consulting Engineers Inc. Technical Information Report Alpine Nursery Page 21 City of Renton ~ ClTil ~ ' O.., Q ""-Q::"" O.""P "'·O "'O"' O...,. o oQo 0 o 0 6°o,oCS'qoo(>0 o Q O O O O q Q 0 o 0 o 0 o 0 o 0 o 0 oqo 0 9 0 Q oAo 0 o 0 o 0 o 0 oQq 0 o 0 o, od°()ooodoooQOQ~dc>,. ooooooooqoqoooooo o Oob 0.0 o 0 o 0 o 0 o 0 .Q" o " n A. -,o_o_o_o.....,o !~H 1~: ::H :;:::::~~;~:~;:~::,,:~:ii,::::::::.::: ,._ ... _,, ': :::: 180THAVESE AREA BREAKDOWN TOTAL EXISTING SITE AREA: TOTAL PROJECT AREA: TOTAL DEVELOPABLE AREA: TOA SOU TH AREA: LOT AREA (COLLECTED): IMPERVIOUS: TILL GRASS: 419,829 S.F. (9.64 AC) 435,880 S.F. (lo.a AC) 403,897 S.F. (9.27 AC) 392,888 S.F. (9.02 AC) 242,330 S.F. (5.563 AC) 98,065 S.F. (2.251 AC) 144,265 S.F. (3.312 AC) *INCLUDES 50% CREDIT FOR BMP REQUIREMENTS ROW AREA (COLLECTED): IMPERVIOUS: TILL GRASS: TRACT B AREA (COLLECTED): IMPERVIOUS: TILL GRASS: 123,177 S.F. (2.828 AC) 123,177 S.F. (2.828 AC) 0 S.F. (0.000 AC) 20,028 S.F. (0.460 AC) 10,014 S.F. (0.230 AC) 10,014 S.F. (0.230 AC) r-:::1 ~ ~ II m ~~g~ !El l ~. ??} ·::::::::::::: ·.·.·.·.·.·.·, :.: .:. :. :.: ·l f.::::::: :=::: 1-:-:-:-:-:-:-....... '• ..... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . •,. ~:.· .... ::::::::::::1 ..... -~.;-~ .. ~ .. ~."'· .~ .. ~.-.. -.. ;' ...... . : : : : : : : :::~: ::.: ::: : : : : : : : : : : : : : -~.w~:j:j:j;j:::~:::;:::j::::::::::: :~~ --· --_ --:::::::::sIT~sT::::::: ttliltltlt}f {jr r ; TRACT C/UNDISTURBEQ AREA: IMPERVIOUS: OUTWASH FOREST: OPEN SPACE AREA: TILL GRASS: BYPASS {161ST A VE SE): IMPERVIOUS: TILL GRASS: BYPASS: IMPERVIOUS: TILL GRASS: 'TO BE FULL Y INFIL TRA TED UPSTREAM TRIBUTARY AREA (COLLECTED): IMPERVIOUS: TILL GRASS: TOA NORTH AREA (NOT COLLECTED): IMPERVIOUS: TILL GRASS: ~: ~: i: ~: ~: ~: ~: i: ~ 1 ~? ! ~ ~ ~ i ! ~ ~~ 31,983 S.F. (0. 734 AC) 0 S.F. (0.0 AC) 31,983 S.F. (0. 734 AC) 1.770 S.F. (0.041 AC) 1,770 S.F. (0. 041 AC) 1,574 S.F. (0.036 AC) 1,110 S.F. (0. 025 AC) 464 S.F. (0.011 AC) 4,009 S.F. (0.092 AC) 3,093 S.F. (0.071 AC) 916 S.F. (0.021 AC) 9,800 S.F (0.225 AC) 4,580 S.F. (0.105 AC) 5,220 S.F (0.120 AC) 11,009 S.F. (0.253 AC) 5,641 S.F. (0.130 AC) 5,368 S.F. (0.123 AC) ' Ct NOR.TH GRAPHIC SCALE 0 50 100 150 1 INCH= 100 FT. R:\2014\0\f4Dli9\J\Drawlngs\Plots\PP\Report ngures\RG6_DEV 14069.dwg 1/12/2015 8:23:22 AM PST COPYRIGHT@ 2015, D.R. STRONG CONSULTING ENGINEERS INC. I I 1~ ~! Q,, i fl) m ,q: fil ~ id ::::i ~ ~ I ~ Ii~ I I i I~ ' ~ ~ '<C ~ ~ ~ 0 ij ).. "' 11! tE &i i.! ~~as ~ix~ w!~ ~Oil~ II.. ... ~ <i! ~ ~ ! ~ ~ ls ~ DRAF7fD BY: CEN D£S/GN£D BY: PROJECT ENGIN£ER: MAJ DA TE: 01.06.15 PROJECT NO.: 14069 F1GVRE: 6 I PERFORMANCE STANDARDS (PART C) The Project is required to adhere to Flow Control Duration Standard, Forest Site Conditions criteria. The Flow Control performance criteria requires that the developed condition's durations must match the predeveloped durations ranging from 50% of the two-year peak flow up to the full 50-year peak flow and also match developed peak discharge rates to predeveloped (forested) peak discharge rates for the 2-year and 10- year return periods (KCSWDM, Sec. 1.2). The Basic Water Quality Treatment goal is to remove 80% of TSS for flows or volumes up to and including the WQ design flow or volume. Conveyance criteria for the Project require that all new pipes be designed to convey and contain (at minimum) the 25-year peak flow. The conveyance system design will be analyzed at time of final engineering. Given the proposed design of a full infiltration pond, the actual discharge from the Project will be limited that which is generated by the bypass area (TOA South) and TOA North. As discussed previously, TOA North was exempt from flow control since the developed 100-year peak flow (0.088 cfs) did not increase by more than 0.1 cfs from the predeveloped 100-year peak flow (0.001 cfs). For TOA South, the Point of Compliance comparison should be made between the predeveloped and 151•1 Bypass time series. Below is the duration analysis curve for the predeveloped and 1a1•1 Bypass basins. PRE-DEVELOPED VS. BYPASS DURATION ANALYSIS :g 0 !+--~-------4~---------- TARGET dur -:- BYPASS.di.Ir • ~ --~, ~ ~I----------<~--'\--------------------- ; ~ ' Oi ~ ~l--------------"----------------- 0 ' of------------------------------- 0 Probability Exceed1mce FLOW CONTROL SYSTEM (PART D) The Site will utilize an infiltration pond meeting the Flow Control Duration Standard, Forested Site Conditions requirements. The King County Runoff Time Series (KCRTS) software was used to size the infiltration facility. The infiltration pond design information is included in this section. ©2015 D.R. STRONG Consulting Engineers Inc. Technical Information Report Alpine Nursery Page 22 Ctty of Renton A measured infiltration rate of 60 inches/hour was found for soils within the site by Earth Solutions, on December 22, 2014. This rate was found using the EPA falling head test. The designed infiltration rate was determined by using the simplified method. IDesign = I Measured X FTesting X FGeometry X FPlugging I Measured= 60 inches/hour FTesting = 0.30 (EPA method) FGeometry = 4 (OM/) + 0.05 = 0.403 D = 3-feet (Depth of pond bottom above ground table) W = 34-feet (Width of pond) FP1ugging = 1.0 (Infiltration Facility preceded by water quality facility) IDesign = 7.2 inches/hour= 8.3 minutes/inch FLOW CONTROL BMP SELECTION Subdivision projects are required to mitigate for impervious surface equal to a minimum of 10% of each lot area by use of Flow Control Best Management Practices (BMP's). The project must analyze the feasibility of infiltration and dispersion of roof runoff. The project may utilize splash blocks, pervious pavement or other BMP's as found in Appendix C of the Manual. Evaluation and inclusion of a BMP will be accomplished at final engineering. As currently proposed, each lot will utilize a drywell a 15-foot long by 10-foot wide by 4-foot deep drywell. The total 600 c.f. of drywell will mitigate an impervious area of 2,608 s.f. on each lot. A 50% surface credit is reflected in the developed area breakdown. ©2015 D.R. STRONG Consulting Engineers Inc. Technical Information Report Alpine Nursery Page 23 City of Renton FLOW CONTROL FACILITY DESIGN OUTPUT Retention/Detention Facility Type of Facility: Infiltration Pond Side Slope: 3. 00 H: 1 V Pond Bottom Length: 155.80 ft Pond Bottom Width: 27 .58 ft Pond Bottom Area: 4296. sq. ft Top Area at 1 ft. FB: 10697. sq. ft 0. 24 6 acres Effective Storage Depth: 4. 00 ft Stage O Elevation: 357.00 ft Storage Volume: 26755. cu. ft 0.614 ac-ft Vertical Permeability: 8.30 min/in Permeable Surfaces: Bottom Riser Head: 4. 00 ft Riser Diameter: 18.00 inches Top Notch Weir: None Outflow Rating Curve: None Stage Elevation Storage Discharge Percolation Surf Area (ft) I ft) (cu. ft) (ac-ft) (cfs) (cfs) (sq. ft) 0.00 357.00 0. 0.000 0.000 0.00 4296. 0.09 357.09 391. 0.009 0.000 0. 72 4396. 0.19 357 .19 836. 0.019 0.000 o. 72 4507. 0.29 357.29 1293. 0.030 0.000 0.72 4618. 0.39 357.39 1760. 0.040 0. 000 0.72 4 731. 0.49 357.49 2239. 0.051 0.000 0. 72 4844. 0.59 357.59 2729. 0.063 0.000 0.72 4958. 0.69 357.69 3230. 0.074 0.000 0.72 5073. 0.79 357.79 3743. 0.086 0.000 0. 72 5188. 0.89 357.89 4268. 0.098 0.000 0.72 5304. 0.99 357.99 4804. 0.110 0.000 0. 72 5421. 1. 09 358.09 5352. 0.123 0.000 0.72 5538. 1.19 358.19 5912. 0 .136 0.000 0.72 5657. 1. 29 358.29 6483. 0.149 0. 000 0.72 5775. 1. 39 358.39 7067. 0 .162 0. 000 0.72 5895. 1. 49 358.49 7662. 0.176 0.000 0.72 6016. 1. 59 358.59 8270. 0 .190 0.000 0.72 6137. 1. 69 358.69 8890. 0.204 0.000 0.72 6258. 1. 79 358.79 9522. 0.219 0.000 0.72 6381. 1. 89 358.89 10166. 0.233 0.000 0. 72 6504. 1. 99 358.99 10823. 0.248 0.000 0. 72 6628. 2.09 359.09 11492. 0.264 0.000 0. 72 6753. 2.19 359.19 1217 3. 0.279 0.000 0. 72 6878. 2.29 359.29 12867. 0 .295 0.000 0. 72 7005. 2.39 359.39 13574. 0.312 0.000 0. 72 7131. 2.49 359.49 14294. 0.328 0.000 0. 72 7259. 2.59 359.59 1502 6. 0.345 0.000 0. 72 7387. 2.69 359.69 15771. 0.362 0.000 0. 72 7516. 2.79 359.79 1652 9. 0.379 0.000 0.72 7646. 2.89 359.89 17300. 0.397 0.000 0. 72 7777. 2.99 359.99 18085. 0. 415 0.000 0.72 7908. ©2015 D.R. STRONG Consulting Engineers Inc. Alpine Nursery Page 24 Technical Information Report City of Renton 3.09 3.19 3.29 3.39 3.49 3.59 3.69 3.79 3.89 3.99 4.00 4.10 4.20 4.30 4.40 4.50 4. 60 4.70 4.80 4.90 5.00 5.10 5.20 5.30 5.40 5.50 5.60 5.70 5.80 5.90 6.00 360.09 360.19 360.29 360.39 360.49 360.59 360.69 360.79 360.89 360.99 361.00 361.10 361. 20 361.30 361.40 361.50 3 61. 60 361. 70 361. 80 361.90 362.00 362.10 362.20 3 62. 3 0 3 62. 4 0 362.50 362.60 362.70 362.80 362.90 363.00 18882. 19693. 20517. 21354. 22205. 23069. 23947. 24838. 25743. 26662. 26755. 27689. 28637. 29600. 30576. 31567. 32571. 33590. 3 4 62 4 • 35672. 36734. 37811. 38 903. 40010. 41131. 42267. 43418. 44584. 45766. 46962. 48174. Hyd Inflow Outflow Peak 0.433 0.000 0.452 0.000 0.471 0.000 0.490 0.000 0.510 0.000 0.530 0.000 0.550 0.000 0.570 0.000 0.591 0.000 0.612 0.000 0.614 0.000 0.636 0.462 0.657 1.310 0.680 2.400 0.702 3.700 0. 725 5.160 0.748 6.590 0. 771 7. 120 0.795 7.610 0.819 8.070 0.843 8.510 0.868 8.920 0.893 9.320 0.918 9.700 0.944 10.070 0.970 10.420 0.997 10.760 1.024 11.100 1.051 11.420 1. 078 11. 730 1.106 12.030 Storage 0.72 0. 72 0. 72 0.72 0. 72 0. 72 0.72 0.72 0.72 0.72 0.72 0. 72 0. 72 0.72 0.72 0.72 0.72 0. 72 0. 72 0. 72 0.72 0.72 0.72 0. 72 0. 72 0. 72 0.72 0.72 0. 72 0. 72 0. 72 Target Cale Stage Elev (Cu-Ft) (Ac-Ft) 1 3.34 ******* 2.10 4.27 361.27 29339. 0.674 2 3 4 5 6 7 8 1.64 0.00 1.74 ******* 1.65 ******* 1.98 ******* 1.71 ******* 1.42 ******* 1.32 ******* 0.00 4.00 361.00 0.00 3.78 360.78 0.00 3.19 360.19 0.00 2.66 359.66 0.00 1.74 358.74 0.00 0.67 357.67 0.00 0.62 357.62 Route Time Series through Facility Inflow Time Series File:dev.tsf Outflow Time Series File:rdout 2 67 5 5. 24729. 19717. 15577. 9201. 3118. 2855. Inflow/Outflow Analysis Peak Inflow Discharge: Peak Outflow Discharge: Peak Reservoir Stage: 3.34 CFS at 6:00 on Jan 2.10 CFS at 9:00 on Jan 4 .27 Ft Peak Reservoir Elev: 361.27 Ft Peak Reservoir Storage: 29339. Cu-Ft 0.674 Ac-Ft Flow Frequency Analysis Time Series File:rdout.tsf Project Location:Sea-Tac ©2015 D. R. STRONG Consulting Engineers Inc. Technical Information Report Alpine Nursery 0.614 0.568 0.453 0.358 0.211 0.072 0.066 9 in Year 8 9 in Year 8 8040. 8172. 8306. 8440. 8575. 8710. 8846. 8983. 9121. 9259. 9273. 9412. 9552. 9693. 9834. 9976. 10119. 10263. 10407. 10552. 10697. 10844. 10991. 11139. 11287. 11437. 11587. 11737. 11889. 12041. 12194. Page 25 City of Renton ---Annual Peak Flow Rates--------Flow Frequency Analysis------- Flow Rate Rank Time of Peak --Peaks --Rank Return Prob (CFS) (CFS) (ft) Period 0.000 2 2/09/01 20:00 2.10 4 .27 1 100.00 0.990 0.000 8 1/05/02 17: 00 0.000 4. 00 2 25.00 0. 960 0.000 5 2/27 /03 10:00 0.000 3.78 3 10.00 0.900 0.000 7 8/26/04 3:00 0.000 3.19 4 5.00 0.800 0.000 6 10/28/04 19:00 0.000 2. 66 5 3.00 0.667 0.000 3 1/18/06 22:00 0.000 1. 74 6 2.00 0.500 0.000 4 11/24/06 7:00 0.000 0. 67 7 1. 30 0.231 2.10 1 1/09/08 9:00 0.000 0. 62 8 1.10 0.091 Computed Peaks 1. 40 4.21 50.00 0. 980 Duration Comparison Anaylsis Base File: predev.tsf New File: bypass(161st).tsf Cutoff Units: Discharge in CFS -----Fraction of Time--------------Check of Tolerance------- Cutoff Base New %Change Probability 0.018 0.23E-02 O.OOE+OO -100.0 I 0.23E-02 0.020 0.18E-02 O.OOE+OO -100.0 I 0.18E-02 0.022 0 .14E-02 O.OOE+OO -100.0 I 0.14E-02 0.024 0.95E-03 O.OOE+OO -100.0 I 0.95E-03 0. 026 0. 72E-03 O.OOE+OO -100.0 I 0. 72E-03 0.028 0.55E-03 O.OOE+OO -100.0 I 0.55E-03 0.030 0. 4 lE-03 O.OOE+OO -100.0 I 0.41E-03 0.032 0.31E-03 O.OOE+OO -100.0 I 0.31E-03 0.034 0.21E-03 O.OOE+OO -100.0 I 0.21E-03 0.036 0.15E-03 O.OOE+OO -100.0 I 0.15E-03 0.038 0.82E-04 O.OOE+OO -100.0 I 0.82E-04 0.040 0.49E-04 O.OOE+OO -100.0 I 0.49E-04 0.042 0.16E-04 O.OOE+OO -100.0 I 0.16E-04 0.044 0 .16E-04 O.OOE+OO -100.0 I 0.16E-04 There is no positive excursion Maximum negative excursion= 0.021 cfs (-81.1%) occurring at 0.026 cfs on the Base Data:predev.tsf and at 0.005 cfs on the New Data:bypass(161st) .tsf ©2015 D.R. STRONG Consulting Engineers Inc. Technical Information Report Alpine Nursery Base New %Change 0.018 0.004 -78.5 0.020 0.004 -7 9. 1 0.022 0.004 -79.6 0.024 0.005 -79.9 0.026 0.005 -80.3 0.028 0.006 -79.6 0.030 0.006 -79.8 0.032 0.006 -80.0 0.034 0.007 -79.5 0.036 0.007 -80.5 0.038 0.008 -79.9 0.040 0.008 -79.3 0.042 0.009 -78.1 0.044 0.009 -79.1 Page 26 City of Renton WATER QUALITY TREATMENT SYSTEM (PART E) The Project is located in the Basic Water Quality Treatment area. The treatment goal is 80% removal of total suspend solids for a typical rainfall year, assuming typical pollutant concentrations in urban runoff. The Project will utilize an infiltration facility and is therefore required to provide water quality treatment prior to infiltration. A StormFilter preceding the infiltration pond will accommodate this requirement. ©2015 o. R. STRONG Consulting Engineers Inc. Technical Information Report Alpine Nursery Page 27 City of Renton FIGURE 7 DETENTION & WATER QUALITY FACILITY DETAILS This will be provided at time of final engineering. ©2015 D. R. STRONG Consulting Engineers Inc. Technical Information Report Alpine Nursery Page 28 City of Renton SECTION V CONVEYANCE SYSTEM ANALYSIS AND DESIGN Per C.R. #4 of the KCSWDM, the conveyance system must be analyzed and designed for existing tributary and developed onsite runoff from the proposed project. Pipe systems shall be designed to convey the 100-year design storm. The Rational Method will be used to calculate the Q-Ratio for each pipe node. Analysis will be performed at final engineering. ©2015 D.R. STRONG Consulting Engineers Inc. Technical Information Report Alpine Nursery Page 29 City of Renton BACKWATER ANALYSIS A backwater analysis will be provided at time of final engineering. ©2015 D.R. STRONG Consulting Engineers Inc. Technical Information Report Alpine Nursery Page 30 City of Renton SECTION VI SPECIAL REPORTS AND STUDIES The following report and studies have been provided with this submittal. 1. Wetland Evaluation -Re-Align Environmental January 4, 2015 2. Traffic Impact Analysis -TraffEx, Inc., December 31, 2014 3. Geotechnical Engineering Study -Earth Solutions NW LLC, June 5, 2014 4. Infiltration Evaluation -Earth Solutions NW LLC, January 9, 2015 5. Arborist Report -GreenForest, Inc., January 5, 2015 6. School Walkway Analysis -D.R. Strong Consulting Engineers, Inc. December 30, 2014 ©2015 D. R. STRONG Consulting Engineers Inc. Technical Information Report Alpine Nursery Page 31 City of Renton SECTION VII OTHER PERMITS, VARIANCES AND ADJUSTMENTS None anticipated at this time. ©2015 D.R. STRONG Consulting Engineers Inc. Technical Information Report Alpine Nursery Page 32 City of Renton SECTION VIII ESC PLAN ANALYSIS AND DESIGN (PART A) The Erosion and Sedimentation Control Design meets the nine minimum requirements: 1. Clearing Limits -Areas to remain undisturbed shall be delineated with a high- visibility plastic fence prior to any Site clearing or grading. 2. Cover Measures -Disturbed Site areas shall be covered with mulch and seeded, as appropriate, for temporary or permanent measures. 3. Perimeter protection -Perimeter protection shall consist of a silt fence down slope of any disturbed areas or stockpiles. 4. Traffic Area Stabilization -A stabilized construction entrance will be located at the point of ingress/egress. 5. Sediment Retention -Surface water collected from disturbed areas of the Site shall be routed through a sediment vault or sediment traps prior to release from the Site. The sediment vault or traps will be installed prior to grading of any contributing area. 6. Surface Water Control -Interceptor berms or swales shall be installed to control and intercept all surface water from disturbed areas. Surface water controls shall be installed concurrently with and/or immediately following rough grading. 7. Dewatering Control -Will be provided as needed. 8. Dust Control -Dust control shall be provided by spraying exposed soils with water until wet. This is required when exposed soils are dry to the point that wind transport is possible which would impact roadways, drainage ways, surface waters, or neighboring residences. 9. Flow Control -Flow control will be provided by sediment traps and the proposed infiltration pond during construction. ©2015 D. R. STRONG Consulting Engineers Inc. Technical Information Report Alpine Nursery Page 33 City of Renton SWPPS PLAN DESIGN (PART B) Construction activities that could contribute pollutants to surface and storm water include the following, with applicable BMP's listed for each item: 1. Storage and use of chemicals: Utilize source control, and soil erosion and sedimentation control practices, such as using only recommended amounts of chemical materials applied in the proper manner; neutralizing concrete wash water, and disposing of excess concrete material only in areas prepared for concrete placement, or return to batch plant; disposing of wash-up waters from water-based paints in sanitary sewer; disposing of wastes from oil-based paints, solvents, thinners, and mineral spirits only through a licensed waste management firm, or treatment, storage, and disposal (TSO) facility. 2. Material delivery and storage: Locate temporary storage areas away from vehicular traffic, near the construction entrance, and away from storm drains. Material Safety Data Sheets (MSDS) should be supplied for all materials stored, and chemicals kept in their original labeled containers. Maintenance, fueling, and repair of heavy equipment and vehicles shall be conducted using spill prevention and control measures. Contaminated surfaces shall be cleaned immediately following any spill incident. Provide cover, containment, and protection from vandalism for all chemicals, liquid products, petroleum products, and other potentially hazardous materials. 3. Building demolition: Protect stormwater drainage system from sediment-laden runoff and loose particles. To the extent possible, use dikes, berms, or other methods to protect overland discharge paths from runoff. Street gutter, sidewalks, driveways, and other paved surfaces in the immediate area of demolition must be swept daily to collect and properly dispose of loose debris and garbage. Spray the minimum amount of water to help control windblown fine particles such as concrete, dust, and paint chips. Avoid excessive spraying so that runoff from the Site does not occur, yet dust control is achieved. Oils must never be used for dust control. 4. Sawcutting: Slurry and cuttings shall be vacuumed during the activity to prevent migration offsite and must not remain on permanent concrete or asphalt paving overnight. Collected slurry and cuttings shall be disposed of in a manner that does not violate ground water or surface water quality standards. The complete CSWPPP will be submitted at the time of final engineering. ©2015 D. R. STRONG Consulting Engineers Inc. Technical Information Report Alpine Nursery Page 34 City of Renton SECTION IX BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT 1. Bond Quantity Worksheet -will be submitted at final engineering 2. The Stormwater Facility Summary Sheet is included in this section 3. Declaration of Covenant-will be provided prior to final engineering approval. ©2015 D.R. STRONG Consulting Engineers Inc. Technical Information Report Alpine Nursery Page 35 City of Renton STORMWATER FACILITY SUMMARY SHEET Development. __ ~A=l~p=in=e~N=u=rs=e=ry~_Date January 5, 2015 Location 16023 SE 144th Street and 14609/14625 161"1 Avenue SE, Renton, Washington ENGINEER Name Maher A. Joudi, P.E. Firm D. R. STRONG Consulting Enaineers, Inc. Address 620 7 .. Avenue Kirkland, WA 98033 Phone (425) 827-3063 Developed Site: 9.12 acres Number of lots 27 Number of detention facilities on Site: vaults ---___ pond tanks --- DEVELOPER Name Roy Boyer Firm Address 14609 161"' Ave SE Renton, WA 98059 Phone (425) 766-3066 Number of infiltration facilities on Site: vaults ---__ 1~pond tanks --- Flow control provided in regional facility (give location) __ -,----,----------- No flow control required ___ Exemption number D ownstream D . ramaae B . asins Immediate Major Basin Basin Lower Cedar River Cedar River Number & type of water quality facilities on Site: biofiltration swale (regular/weU or continuous inflow?) ___ sand filter (basic or large?) ___ sand filter, linear (basic or large?) combined detentionNVQ vault --- __ combined detention/wetpond ___ compost filter ___ filter strip ___ flow dispersion ___ farm management plan ___ landscape management plan 1 CONTECH Stormfilter ___ sand filter vault (basic or large?) stormwater wetland --- ___ wetvault (basic or large?) Wetvault ---___ pre-settling pond ___ flow-splitter catchbasin ___ oil/water separator (baffle or coalescing plate?) ©2015 D. R. STRONG Consulting Engineers Inc. Technical Information Report Alpine Nursery Page 36 City of Renton ___ catch basin inserts: Manufacturer ---------------------___ pre-settling structure: Manufacturer ___________________ _ DESIGN INFORMATION INDIVIDUAL BASIN Water Qualitv desian flow Water Qualitv treated volume Drainaae basin/s) TOA South Onsite area (includes frontaae) 9.12 Offsite area Type of Storage Facility Infiltration Pond Live Storaae Volume /re< uiredl 26,755 Predev Runoff Rate 2-vear 0.036 10-vear 0.042 100-vear 0.079 Develooed Runoff Rate 2-vear 0.007 /includes bvoass) 10-vear 0.009 100-vear 2.114 Tvoe of Restrictor N/A Size of orifice/restriction No. 1 No. 2 No. 3 ©2015 D.R. STRONG Consulting Engineers Inc. Technical Information Report Alpine Nursery Page 37 City of Renton SECTION X OPERATIONS AND MAINTENANCE MANUAL Excerpts from the 2009 KCSWDM will be provided at final engineering. ©2015 D.R. STRONG Consulting Engineers Inc. Technical Information Report Alpine Nursery Page 38 City of Renton OFFSITE ANALYSIS ©2015 D.R. STRONG Consulting Engineers Inc. Technical Information Report APPENDIX A Alpine Nursery Page 39 City of Renton LEVEL ONE DOWNSTREAM ANALYSIS for ALPINE NURSERY Preliminary Plat 16023 SE 144'" Street and 14609/14625 161'1 Avenue SE, Renton, Washington DRS Project No. 14069 Renton File No. LUA XXXXXX Owner/Applicant Roy Boyer 14609 161 51 Ave SE Renton, WA 98059 Report Prepared by UM D. R. STRONG Consulting Engineers, Inc. 620 ?1h Avenue NE Kirkland WA 98033 (425) 827-3063 ©2015 D.R. STRONG Consulting Engineers lnc. Report Issue Date January 12, 2015 LEVEL ONE DOWNSTREAM ANALYSIS ALPINE NURSERY TABLE OF CONTENTS TASK 1 DEFINE AND MAP THE STUDY AREA ......................................................... 2 TASK 2 RESOURCE REVIEW ..................................................................................... 6 TASK 3 FIELD INSPECTION ..................................................................................... 16 Upstream Tributary Area ........................................................................................... 16 General Onsite and Offsite Drainage Description ..................................................... 16 TASK 4 DRAINAGE SYSTEM DESCRIPTION AND PROBLEM DESCRIPTIONS ... 17 Drainage System Description .................................................................................... 17 Downstream Path TOA .............................................................................................. 17 TASK 5 MITIGATION OF EXISTING OR POTENTIAL PROBLEMS ......................... 21 APPENDIX A ................................................................................................................ 23 APPENDIX B ................................................................................................................ 26 List of Figures Figure 1. Vicinity Map ...................................................................................................... 3 Figure 2. Site Map ........................................................................................................... 4 Figure 3. City of Renton Topography .............................................................................. 5 Figure 4. Streams and 100-Year Floodplains and Floodway ........................................... 7 Figure 5. City of Renton Wetlands ................................................................................... 8 Figure 6. City of Renton Erosion Hazard Areas .............................................................. 9 Figure 7. King County iMap Landslide Hazard Areas .................................................... 10 Figure 8. City of Renton Seismic Hazard Areas ............................................................ 11 Figure 9. FEMA -Flood Insurance Rate Map ............................................................... 12 Figure 10. King County iMap Drainage Complaints ...................................................... 13 Figure 11. USDA King County Soils Survey Map .......................................................... 14 Figure 12. Downstream Table ....................................................................................... 24 Figure 13. Downstream Map ......................................................................................... 30 ©2015 D.R. STRONG Consulting Engineers lnc. Level One Downstream Analysis Alpine Nursery Page 1 Ctty of Renton DISCLAIMER: THIS REPORT WAS PREPARED AT THE REQUEST OF ROY BOYER FOR THE 9.638 ACRE PARCELS KNOWN AS A PORTION OF THE NORTHEAST QUARTER OF SECTION 23, TOWNSHIP 23 NORTH, RANGE 5 EAST, W.M., IN KING COUNTY, TAX PARCEL NUMBER 232305-9004, -9099, AND -9167 (SITE). D. R. STRONG CONSUL TING ENGINEERS INC. (DRS) HAS PREPARED THIS REPORT FOR THE EXCLUSIVE USE OF DRS, THE OWNER, AND THEIR AGENTS, FOR SPECIFIC APPLICATION TO THE DEVELOPMENT PROJECT AS DESCRIBED HEREIN. USE OR RELIANCE ON THIS REPORT, OR ANY OF ITS CONTENTS FOR ANY REVISIONS OF THIS PROJECT, OR ANY OTHER PROJECT, OR BY OTHERS NOT DESCRIBED ABOVE, IS FORBIDDEN WITHOUT THE EXPRESSED PERMISSION BY DRS. TASK1 DEFINE AND MAP THE STUDY AREA This Offsite Analysis was prepared in accordance with Core Requirement #2, Section 1.2.2 of the 2009 King County Surface Water Design Manual (Manual) as adopted by the City. The Site is located at 16023 SE 144th Street and 14609/14625 161st Avenue SE in Renton, Washington. See Figure 1, Figure 2, and Figure 3 for maps of the study area. ©2015 D.R. STRONG Consulting Engineers Inc. Level One Downstream Analysis Alpine Nursery Page 2 City of Renton FIGURE 1. VICINITY MAP The information inclu ded on th is map has been compi l ed by King Count y staff from a variety of sources and is subject to change wi th ou t notice. King Coun ty makes no represent ations or wa rranties , express or i mplied , as to accuracy, completeness , timel ines s. or rights to the use of such information. King County shall not be liable for any general, special . indirect . incidental, or consequential damages inc lud ing , bu t not lim ited t o, lost revenues or lost profits resulting from the use or misuse of the information contained on this map. Any sale of th is map or information on this map is proh ibited except by written p erm issi on of Ki ng County . <0 20 15 D.R . ST RONG Consulting Eng ineers Inc. Level O ne Downstream Analysis Alpi ne Nursery Page 3 City of Renton ©2015 D.R. STRONG Consulting Engineers Inc. Level One Downstream Analysis FIGURE 2. SITE MAP Alpine Nursery Page4 City of Renton /' I J 1: / I ,1 I i 1 -. • I !1 I \ • I -a 1 -11 11 , _· ~II , u -,·-; . \ I u I :-( • ·1.; _) ·"-x-ic-ll'--._~-t- ~ 1 I ~ I / ____ / / i H ---illO H / / I I . 1 I j I ----i f I :: I rff I r-1 L ; CT . ; J :: I I I! f II t ~ N I i z : II I I l I . ll II I I I -II I ! t 1 · "1 w. 1:~' r· • 11 1 1 B5 I :J ,y- I • I ~ ;11m-·, : o I ; 7 • \ ----B ----- --1----- "" ·i;.-:--- ~- / f' Ii I 8 .• i I IS . ---...... __ I • L __ I J I I I . • I l }I ~-==-----· ~ ~ _.,,. • 4 ~ ;-x x· I I ~---!---- ~ ; I I · I / ,1 . I • I ii / f j . ia i / 1 I -1hl 11 ,, J I \ , " I I ·iii 1,1 I: -- /, ( ---~~ ®.>~~~ . • 5 ... . ··., .j ' ' ·. . •. ., ' : \ ; --; -· ~.:=:"'--"' \ ' I \ --r I ' --I ':",;-'._.,_, ,) ,__ -I --',,~ I _··. ii! r :_ r_ :_ 1~-__ . ·. , mn U: . ~-~ '. . . ' ', i • • • • 5 • I ~~-\ ·-: II 1:;iJ -~-... 11 / > I' ~ . I ,_ ' I ~-------.~;N.! ·-... '--:\ -• ~· \ --;-tn: • • •• \) ! LLJI ·1 1.-·. i i ,,J w 1 r11.···· ., . . . _.,-\ I ·.·; ·I .• I \ ...... / } ),!11 f I -I i I I --4--', . ,/ '' ' . ) .Y \ I • , I ' I =:.:::.', -, I I \.....-- 0 <I • ! ill 11~ ·~ --- ' ...... "'•', __ ,,,.,,,,., ,,._ / : / j"\ --1, /•& -j" \ ·, // // ., \ . ' ,._______-, I'.._ \ . , , •1 ( I I / I I f / ,i ! I ,_! ,, .~ / "'l ) I ~ // ' •l!I ( rj . Ii .; \ I . ·~ \/ -/I ,-. I ' . " ; / ("\ - / I I \ \ / .. ~ ~ I 1/·1 k=·:::+' .... !6.P!rl. AVf .. S.~ 1 ~jf Iii ·,-·-1 ... . . ... -~-' ··1········ ····-<J·· ..... · ··· ······· L '~ _ ~!jt I!! .. <1] 1: @ NOR.TH GRAPHIC SCALE 0 40 80 120 1 INCH= 80 FT. R: \2014\0\14069\.J\Orawlngs\Plats\PP\Repart Rgures\3SM14D69.dwg 1/12/2015 8: 10: 11 AM PST COPYRIGHT_@. 2014, D.R. STRONG CONSULTING ENGINEERS INC. I ljj ,~ ~1 ~I~ Ii~ I, i lfi ~ f ~ 0 ti lg ~ "( ... l'J) ... ~ ).. I() !)) Q. t:i ~ is s: Cl) :!: a! ii! ~~~ ~ ~ :!: ~- u; ~ ~~ ~~~ ! lg ~ ~ ... DRAF7ED BY: CEN DE:SK;NCD BY: PROJECT ENGINEER: MAJ DA1E: 12.16.2014 PROJECT NO.: 14069 FIGURE: 2 I FIGURE 3. CITY OF RENTON TOPOGRAPHY ,..,, 1+11t u4,• ..... "'" ..... , • ..... ""' - M )i~ -..... • I I i ""' l ; SE 1~1" St. ; I i .. .i "'" ""' i I ; i 1St'17 "::'., IMO$ i ... ,. , l ,, I ; I u.,m I I I I I I ' i I I I I I i I :j I I l i L. "'" 1!.t)O 0 0 128 1ffU' ©2015 D.R. STRONG Consulting Engineers Inc. Level One Downstream Analysis ""' '"" ..... ,..,, ""' t41JO ,u1M H,QI 1111-4 Site ,., .,. ·--·-·-·-·-·-·-·-·-·-..... ~ ...... ·-'{ /' B ·~ IU02 , ~ 'I 144M , 1440il 'i Ip ~. J 14'10 :"' , I I I / HUI ! I I ! I ... ,. / ' .;,,. ! tf10ol "" ~, it.I .,,.\ j\ 111' rn!. mOJ \ ,\ ' 1\ ; I \ \ I \ \ t ' \ "' ...... '/tun 16117 .. ·: HUJ · 1&110 IIUO \ ·-mu ""' ' I .! ~., l_,&Ul ·UIM Hill , . ""' IUU 1"41 · 250- I ' INN ~; ..... ---,_ w•-w•-........ ~---....... ..,_ ..,_ .,_, .,_ ,._ ·--- Alpine Nursery "'" IUU Page 5 Crty of Renton TASK2 RESOURCE REVIEW • Adopted Basin Plans: Lower Cedar River Basin and Nonpoint Action Plan was adopted in July 1998. • Floodplain/Floodway (FEMA) Map: No floodplains exist on site, See Figure 9. • Other Offsite Analysis Reports: None available at this time. • Sensitive Areas Folio Maps: See Figures 4-8 for documentation of the distance downstream from the proposed project to the nearest critical areas. Included, are sections of the City of Renton Mapping Application and King County Sensitive Areas Folio which indicate the following: • Figure 4 Streams and 100-Year Floodplains and Floodway: There is one Type 1 river, Cedar River to the south, within one mile of the Site. A 100-year floodplain is within one mile of the Site along Cedar River. • Figure 5 Wetlands: There is one wetland around a porlion of Cedar River within one mile of the Site along the downstream path. • Figure 6 Erosion Hazard: There are mapped Erosion Hazard Areas within one mile of the Site along the downstream path. • Figure 7 Landslide Hazard: There are mapped Landslide Hazard Areas within one mile of the Site along the downstream path. • Figure 8 Seismic Hazard: There are mapped Seismic Hazard Areas within one mile of the Site along the downstream path. • DNRP Drainage Complaints and Studies: As shown in Figure 10, there are drainage complaints within 1 mile of the Site along the downstream path. There are three drainage complaints on Site but they regard fee re-measurement and are not relevant to this reporl. The other drainage complaints within one mile along the downstream path are not relevant to a Level One Analysis. See Task 5. • Road Drainage Problems: None noted. • USDA King County Soils Survey: See Figure 11. • Wetlands Inventory: The wetland inventory revealed no additional wetlands within the downstream path. • Migrating River Studies: None are applicable to the site. • Washington State Department of Ecology's latest published Clean Water Act Section 303d list of polluted waters: None listed along the downstream path. • King County Designated Water Quality Problems: None at this time. • Adopted Stormwater Compliance Plans: City of Renton Storm Water Management Plan; King County 2013 Stormwater Management Plan • Basin Reconnaissance Summary Reports: Cedar River Current and Future Conditions Report (April 1993). ©2015 D.R. STRONG Consulting Engineers Inc. Level One Downstream Analysis Alpine Nursery Page6 City of Renton FIGURE 4. STREAMS AND 100-YEAR FLOODPLAINS AND FLOODWAY - 0 1023 0 512 ©2015 D.R. STRONG Consulting Engineers Inc. Level One Downstream Analysis i I I ...,. --·-·-·-·-·--·-·--·-·-I ! ' I ' Site I I I ' ', , ' ' I I I I r"-·-·-·-·---,,·-·-·-·· i -··-·-· ·t:_ .. -.. -· -.. -·-· '-· -' 1023- ,•, ._ .. _ '. - "'""' ,.,,_ ''""" --- ... -- -~~"--(100 ....... M 00., ROlld"'-a-X. SI» ---- Alpine Nursery ' ' i ' ...... Page? City of Renton FIGURE 5. CITY OF RENTON WETLANDS ' ; ; i . ' l '·, I ' ! Site : ' I .---,,{,,.-·--·-·--·~·-----... --....... ........ ·-.-·-·-·-·-·-·---...... ~~ - 0 _,,...--...... -- CJ Ult•--w,,_ ~·-..,,,_ ~·---....... ---' 1023 0 512 1023-Ill- ©2015 D.R. STRONG Consulting Engineers Inc. Level One Downstream Analysis Alpine Nursery ' I ! ' ! ' ' '~ ·····-...... ~ ... -·-·-·----.... 'L.-... ' ! ' I ' ---. ,_._! Page 8 City of Renton FIGURE 6. CITY OF RENTON EROSION HAZARD AREAS ............... ....... ........ 1 -·-. -...... , --- ' I I I I ; I I I I -·-·-·-·-·-·-·-·-. -·-·-·--·--·-. I i I I i i I ' I I I I I I ..... -............ - 0 1023 0 512 ©2015 D.R. STRONG Consulting Engineers Inc. Level One Downstream Analysis -.. .. __ _ 1023,... c-; """·--'. l wn.... n:~ ·; WF'lc:ol ~J 0.,. ........ -· ·- Alpine Nursery I ~~-r---------· I ! ..,_,_, -Site -·-...... _ ... __ ~ .... _ Page 9 City of Renton FIGURE 7. HAZARD AREAS AP LANDSLIDE • TY IM · "I i KING COUN i . i J. . . . ... I ..••••. ~ ... ...,... ·-. . . I 111 : I! i i i --.. Ill Hlghllghlad Featura ,._ -· Boundary -, _ .. , I -Mountain Peak• X Highways Streets r,v1' HitfwM, t/~· (cont) NG Consulting Eng ©2015 D.R. STn~~eam Analysis Level One Dow ,...,, -;' Art.-, .• l.• Loca: Legend Pan~el• Rivera Lakes and Large g Streamo fill! SAO Landslide ineers Inc. Alpine Nursery i • I \. '$ • ·. Site """"" l • • • i i .. ..... ., "'" Page 10 City of Renton FIGURE 8. CITY OF RENTON SEISMIC HAZARD AREAS 0 1023 0 ~12 ©2015 D.R. STRONG Consulting Engineers Inc. Level One Downstream Analysis 1023,.. . -·-·-·-·-·-·-·-·-· .. ·-·-·-·-·-i ~·-: ()hr~ ....... , .... • ~111:'Md,U.. Alpine Nursery i i i I i j ' I ; I ' Site Page 11 City of Renton FIGURE 9. FEMA-FLOOD INSURANCE RATE MAP ... 23 ~'T~:~>o ...,---,;.-,~,LT l l ! NOTE: MAI AREA SHOWN ON THIS PANEL IS lOCATED z· ,OWNSH" ,a NOnH AND OANGE S EAS,. AW!!O>:,M>'ESr.;..,r ~H[' ~ ..... I ..,,.,, IIJI' IMSm 111115,15"1 -·-"-'.':-J ©2015 D.R. STRONG Consulting Engineers Inc. Level One Downstream Analysis ZONE X -~ I, • is".::' ~ I """""' .. I -'= f .$ .. -i i ~ s '""""" ~ 23 \ i i i ti .. "™ """ ---"'"" - --~ ,, ~--------~--~--'-------- -.UII-- FIRM fLGID INSURAla UTE 1W ~-·.!~------ Alpine Nursery Page 12 City of Renton FIGURE 10. KING COUNTY IMAP DRAINAGE COMPLAINTS \ ""' ~ "-, ,~1:. ' ' ' Ill S1ltcted P1rcel1 .-_. Coool)'Bollldary X -ntaln Ptakt Hlgllwayt ' \, ,II' lncorporaiad Ania StrHta (coot) Legend Parcel• 0 Lak11 and Larga Riven // Sb'e8111$ • Dr11na111 eomp111nto ©2015 D.R. STRONG Consulting Engineers Inc. Level One Downstream Analysis Alpine Nursery w \" G t .. ' •• I l'E~ff \ • i • C ~ .. I Page 13 City of Renton FIGURE 11. USDA KING COUNTY SOILS SURVEY MAP 0 • --•lS,;===.,"""-----..,======L'.~ ,~ -"!!so,===;100;!'!"--•x,,~==-;."' ~~-n \Wt)~ (O!UU-U"Jrlft!,;i',GS84 ~lb,:~]il-..,1fJl'I~ lf'iD\ Natt,31 R~s iilaiii Conse-<Y.Mion Se-nria- 62015 D. R. STRONG Consulting Engineers Inc. Level One Downstream Analysis Web Soil Sun.-ey N.Jb:H'\..1.l Cooper.JWe Scil 5urve)' Alpine Nursery 121,~20;4 P.-,ge 1 cl 3 Page 14 City of Renton EvB-Everett gravelly sandy loam, 0 to 5 percent slopes Map Unit Setting • National map unit symbol: 1 hmt2 • Mean annual precipitation: 30 to 45 inches • Mean annual air temperature: 50 degrees F • Frost-free period: 180 days • Farmland classification: Prime farmland if irrigated Map Unit Composition • Everett and similar soils: 100 percent • Estimates are based on observations, descriptions, and transects of the mapunit. Description of Everett Setting • Landform: Terraces • Parent material: Glacial outwash with a component of volcanic ash in the upper part Typical profile • H1 -O to 17 inches: gravelly ashy sandy loam • H2 -17 to 32 inches: very gravelly sandy loam • H3 -32 to 60 inches: very gravelly coarse sand Properties and qualities • Slope: 0 to 5 percent • Depth to restrictive feature: More than 80 inches • Natural drainage class: Somewhat excessively drained • Capacity of the most limiting layer to transmit water (Ksat): High (1.98 to 5.95 in/hr) • Depth to water table: More than 80 inches • Frequency of flooding: None • Frequency of ponding: None • Available water storage in profile: Low (about 5.0 inches) Interpretive groups • Land capability classification (irrigated): None specified • Land capability classification (nonirrigated): 3s • Hydrologic Soil Group: A • Other vegetative classification: Droughty Soils (G002XN402WA) ©2015 D.R. STRONG Consulting Engineers Inc. Level One Downstream Analysis Alpine Nursery Page 15 City of Renton TASK3 FIELD INSPECTION UPSTREAM TRIBUTARY AREA In evaluating the upstream area, we reviewed King County iMAP aerial topography, City of Renton Mapping Application, conducted field reconnaissance and have concluded that upstream tributary area for the Site is minimal. Upstream runoff from the north appears to be collected into the pipe/ditch conveyance system along the north side of SE 144th Street. 161 61 Avenue SE bordering the eastern property line slopes east and directs runoff away from the Site. Topography shows the west and south properties slope away from the Site. There is upstream runoff from Parcel 2323059156 that is in the northwest corner of the Site. This property conveys runoff south onto the Site and the upstream tributary area is considered minimal. GENERAL ONSITE AND OFFSITE DRAINAGE DESCRIPTION Runoff travels south and southwest as sheet flow across the property over grass, dense brush, and soil/gravel driving paths. The Site contains two Threshold Discharge Areas (TDA), TOA South and TOA North. TOA South consists of everything except approximately 0.5 acres of the northeast portion of the Site. The discharge point of TOA South is approximately the western half of the south property line. Runoff sheet flows onto the properties to the south of the Site and continues south through the public conveyance system. Runoff eventually reaches the Cedar River approximately 0.5 miles south of the Site. TOA North consists of approximately 18,929 s.f. of the northeast portion of the property. Runoff sheet flows north into the conveyance system in SE 144th Street. Runoff continues west through the conveyance system in SE 144th Street and then crosses underneath 154th Place SE where it outlets to Stewart Creek, a Class 3 stream. Stewart Creek outlets to Cedar River approximately 0.4 miles west of the Site. ©2015 D. R. STRONG Consulting Engineers Inc. Level One Downstream Analysis Alpine Nursery Page 16 City of Renton TASK 4 DRAINAGE SYSTEM DESCRIPTION AND PROBLEM DESCRIPTIONS DRAINAGE SYSTEM DESCRIPTION The downstream analysis is further illustrated and detailed in the Downstream Map and Downstream Table located in Appendix A. The downstream area is located within the Lower Cedar River basin. The downstream area was evaluated by reviewing available resources, and by conducting a field reconnaissance on December 17, 2014 under cloudy/rainy conditions. The Site contains two TDA's, TOA North and TOA South. Runoff from TOA South exits along the south property line. Runoff continues south as sheet flow across adjacent properties to the south before it enters the conveyance system in the cul-de-sac of 1601h Place SE which outlets to the ditch at the northeast corner of SE 1481h Street and 1601h Place SE. Flow enters a Type 2 catch basin east of the intersection approximately 100' and follows the conveyance system west in SE 1481h Street and then south in 1601h Place SE. At the corner of SE 1491h Street and 1601h Place SE runoff is directed southwest through a property and conveyed down the hillside throu~h an 18" HOPE pipe. Flow continues south through the conveyance system in 160 h Place SE and eventually outlets to Cedar River. Runoff from TOA North sheet flows north and into a catch basin on the south side of SE 1441h Street. Flow enters the conveyance system in SE 144th Street and continues west for approximately 0.25 miles towards the intersection with 1561h Avenue SE. Runoff continues west in the in the dirt road west of SE 1441h Street and then crosses underneath 154th Place SE where it outlets to Stewart Creek, a Class 3 stream. Stewart Creek outlets to Cedar River approximately 0.4 miles west of the Site. Downstream Path TDA South Point "A" is the natural discharge point of TOA South. Runoff is conveyed south across the south property line as sheet flow (±0'). From Point "A" to Point "B", runoff heads south as sheet flow to the paved cul-de-sac of 1601h Place SE (±0'-11 O'). Point "B", runoff enters the paved cul-de-sac of 1601h Place SE (±110'). From Point "B" to Point "C", runoff heads south as sheet flow. No flow was observed (±110'-275'). Point "C", runoff enters a grass-lined ditch located on the northeast corner of SE 1481h Street and 1601h Place SE (±275'). From Point "C" to Point "D", runoff heads west as channel flow in the grass lined ditch (6' top, 1.5' deep, 1.5' bottom). No flow observed (±275'-477'). Point "D", runoff enters a 12" corrugated metal pipe (CMP) located on the north side of SE 1481h Street (±477'). From Point "D" to Point "E", runoff continues west as pipe flow via a 12-inch diameter CMP. No flow was observed (±477'-490'). ©2015 D. R. STRONG Consulting Engineers Inc. Level One Downstream Analysis Alpine Nursery Page 17 City of Renton Point "E", runoff enters a Type 2 catch basin at the east end of SE 1481h Street on the north side (±490'). From Point "E" to Point "F", runoff continues south as pipe flow via a 12-inch diameter CMP. No flow was observed (±490'-528'). Point "F", runoff enters a Type 1 catch basin located at the east end of SE 1481h Street on the south side (±528'). From Point "F" to Point "G", runoff heads east as pipe flow via a 12-inch diameter reinforced concrete pipe (RCP). No flow was observed (±528'-639'). Point "G", runoff enters a Type 2 catch basin located at the intersection of SE 1481h Street and 1601h Place SE (±639'). From Point "G" to Point "H", runoff heads south as pipe flow via a 12-inch diameter RCP. No flow was observed (±639'-865'). Point "H", runoff enters a Type 2 catch basin on the west side of 1601h Place SE (±865'). From Point "H" to Point "I", runoff continues southeast as pipe flow via a 12-inch diameter RCP. No flow was observed (±865'-940'). Point "I", runoff enters a Type 2 catch basin located on the south side of SE 1491h Street (±940'). From Point "I" to Point "J", runoff heads southwest as pipe flow via a 12-inch diameter RCP. No flow was observed (±940'-1, 161'). Point "J", runoff enters a Type 2 catch basin located in the southwest corner of parcel 7806500240 (±1,161'). From Point "J" to Point "K", runoff continues south as pipe flow via an 18-inch diameter high-density polyethylene (HOPE) pipe. The HOPE pipe becomes an above ground pipe approximately 35' south of parcel 7806400240. Catch basin was inaccessible (±1, 161 '-1,624'). Point "K", runoff enters a Type 2 catch basin located on the eastern portion of Parcel 7806450140 (±1,624'). Runoff continues south in the conveyance system in 160 1h Place SE and outlets to Cedar River approximately 0.5 miles south of the Site. Downstream Path TDA North Point "A2" is the natural discharge point of TOA North. Runoff is conveyed northwest to SE 1441h Street as sheet flow (±0'). From Point "A2" to Point "B2", runoff heads northwest as sheet flow to the catch basin on the south side of SE 1441h Street at the approximate midpoint of the north property line (±0'-19'). Point "B2", runoff enters a catch basin on the south side of SE 144th Street at the approximate midpoint of the north property line (±19'). From Point "B2" to Point "C2", runoff heads west as pipe flow via an 18-inch diameter corrugated metal pipe (CMP). Flow observed (±19'-219'). ©2015 D.R. STRONG Consulting Engineers Inc. Level One Downstream Analysis Alpine Nursery Page 18 Cny of Renton Point "C2", runoff enters a Type 1 catch basin located at the southeast corner of SE 1441h Street and 1601h Avenue SE (±219'}. From Point "C2" to Point "02", runoff heads west as pipe flow via an 18-inch diameter CMP. Flow observed (±219'-260'}. Point "02", runoff enters a Type 1 catch basin located at the southwest corner of SE 1441h Street and 1601h Avenue SE (±260'}. From Point "02" to Point "E2", runoff heads west as pipe flow via an 18-inch diameter CMP. Flow observed (±260'-378'}. Point "E2", runoff enters a Type 1 catch basin on the south side of SE 1441h Street (±378'}. From Point "E2" to Point "F2", runoff continues west as pipe flow via an 18-inch diameter CMP. Flow observed (±378'-523'}. Point "F2", runoff enters a Type 1 catch basin located on the south side of SE 144th Street (±523'). From Point "F2" to Point "G2", runoff continues west as pipe flow via an 18-inch diameter CMP. Flow observed (±523'-689'). Point "G2", runoff enters a Type 1 catch basin located on the southeast corner of SE 1441h Street and 1581h Place SE (±689'}. From Point "G2" to Point "H2", runoff continues west as pipe flow via an 18-inch diameter CMP. Flow observed (±689'-832'}. Point "H2", runoff enters a Type 1 on the south side of SE 1441h Street (±832'}. From Point "H2" to Point "12", runoff continues west as pipe flow via an 18-inch diameter CMP. Flow observed (±832'-1,009'}. Point "12", runoff enters a Type 1 catch basin located on the south side of SE 1441h Street (±1,009'}. From Point "12" to Point "J2", runoff continues west as pipe flow via an 18-inch diameter CMP. Flow observed (±1,009'-1, 188'). Point "J2", runoff enters a Type 1 catch basin on the south side of SE 144th Street (±1, 188'}. From Point "J2" to Point "K2", runoff continues west as pipe flow via an 18-inch diameter CMP. Flow observed (±1,188'-1,360'}. Point "K2", runoff enters a Type 1 catch basin on the south side of SE 144th Street (±1,360'}. From Point "K2" to Point "L2", runoff continues west as pipe flow via an 18-inch diameter CMP. Flow observed (±1,360'-1,511 '}. Point "L2", runoff enters a Type 1 catch basin on the south side of SE 144th Street (±1,511 '}. This is just past the quarter mile downstream path for NOA North. Runoff continues west in this conveyance system and is directed southwest across 1541h Place ©2015 D.R. STRONG Consulting Engineers Inc. Level One Downstream Analysis Alpine Nursery Page 19 Crty of Renton SE where it outlets to Stewart Creek which outlets to Cedar River approximately 0.4 miles west of the Site. ©2015 D.R. STRONG Consulting Engineers Inc. Level One Downstream Analysis Alpine Nursery Page 20 City of Renton TASKS MITIGATION OF EXISTING OR POTENTIAL PROBLEMS A review of the King County Water and Land Resources Division -Drainage Services Section Documented Drainage Complaints within one mile of the downstream flow paths revealed 3 complaints within the last ten years. Two of the complaints are a special permit use request and the other a water quality complaint, both of which are not relevant to a Level One downstream analysis. The third complaint is a residential facility complaint regarding dumping of sod by an adjacent property owner and is not applicable to this analysis. A map of the drainage complaints along the downstream path is shown in Appendix B. Project runoff will be collected and released per the Manual's requirements to accommodate Flow Control Duration Standard, Forested Site Conditions and Basic Water Quality requirements. During construction, standard sediment and erosion control methods will be utilized. This will include the use of a stabilized construction entrance, perimeter silt fencing, and other necessary measures to minimize soil erosion during construction. The project should not create any problems as specified in Section 1.2.2.1 of the Manual and therefore is not required to provide Drainage Problem Impact Mitigation subject to the requirements of Section 1.2.2.2. ©2015 D.R. STRONG Consulting Engineers Inc. Level One Downstream Analysis Alpine Nursery Page 21 City of Renton Complaint Parcel Summary Recurring number 2006-0552 1079300100 Special use No permit requesting private use of pond 2002-0244 7806450230 Adjacent No property owner dumping sod. 2011-1008 232305HYDR Two televisions No ©2015 D.R. STRONG Consulting Engineers Inc. Level One Downstream Analysis dumped into Cedar River Alpine Nursery Type N/A N/A N/A Required Mitigation None None None Page 22 Ctty of Renton APPENDIX A. OFFSITE ANALYSIS DRAINAGE SYSTEM TABLE & DOWNSTREAM MAP ©2015 D.R. STRONG Consulting Engineers Inc. Level One Downstream Analysis Alpine Nursery Page 23 City of Renton Basin: Cedar Riv~r Symbol Drainage Drainage Component Component Type, Description Name, and Size Type: sheet flow, See map swale, Stream, drainage basin, vegetation, cover, channel, pipe, depth, type of sensitive area, volume Pond; Size: diameter Surface area A NATURAL WESTERN HALF OF SOUTH DISCHARGE POINT PROPERTY LINE A-B SOUTHERLY SHEET NATIVE VEGETATION/ GRASS FLOW B CUL-DE-SAC 160'" PAVED CONVEYANCE SYSTEM PLSE B-C SOUTHERLY SHEET PAVED CONVEYANCE SYSTEM FLOW C DITCH GRASS-LINED DITCH C-D WESTERLY GRASS-LINED DITCH CHANNEL FLOW (6'TOP, 1.5' DEEP, 1.5' BOTTOM) D PIPE INLET 12" 0 CMP D-E WESTERLY PIPE 12" 0 CMP FLOW ©2015 D.R. STRONG Consulting Engineers Inc. Level One Downstream Analysis FIGURE 12. DOWNSTREAM TABLE TOA South Subbasin Number: Lower Cedar River Slope Distance Existing Potential From site Problems Problems Discharqe Constrictions, under capacity, ponding, % 1/4 mi=1,320 ft overtopping, flooding, habitat or organism destruction, scouring, bank sloughing, sedimentation, incision, other erosion ±0' NONE NONE OBSERVED ANTICIPATED NONE NONE OBSERVED ANTICIPATED ±110' NONE NONE OBSERVED ANTICIPATED NONE NONE OBSERVED ANTICIPATED ±275' NONE NONE OBSERVED ANTICIPATED NONE NONE OBSERVED ANTICIPATED ±477' NONE NONE OBSERVED ANTICIPATED NONE NONE OBSERVED ANTICIPATED Alpine Nursery Observations of field inspector resource reviewer, or resident tributary area, likelihood of problem, overflow pathways, potential impacts. NO FLOW OBSERVED NO FLOW OBSERVED NO FLOW OBSERVED NO FLOW OBSERVED Page 24 City of Renton E E-F F F-G G G-H H H-1 I I-J J J-K CATCH BASIN -INLET (E) -OUTLET (S) SOUTHERLY PIPE 12" 0 CMP FLOW CATCH BASIN -INLET (N) -OUTLET (E) EASTERLY PIPE 12" 0 RCP FLOW CATCH BASIN -INLET (vV) -OUTLET (S) SOUTHERLY PIPE 12" 0 RCP FLOW CATCH BASIN -INLET (N) -OUTLET (SE) SOUTHEASTERLY 12" 0 RCP PIPE FLOW CATCH BASIN -INLET (NW) -OUTLET (SW) SOUTHWESTERLY 12" 0 RCP PIPE FLOW CATCH BASIN -INLET (NE) -OUTLET (S) SOUTHERLY PIPE 18" 0 HDPE FLOW ©2015 D. R. STRONG Consulting Engineers Inc. Level One Downstream Analysis ±490' NONE OBSERVED NONE OBSERVED ±528' NONE OBSERVED NONE OBSERVED ±639' NONE OBSERVED NONE OBSERVED ±865' NONE OBSERVED NONE OBSERVED ±940' NONE OBSERVED NONE OBSERVED ±1, 161' NONE OBSERVED NONE OBSERVED Alpine Nursery NONE ANTICIPATED NONE ANTICIPATED NONE ANTICIPATED NONE ANTICIPATED NONE ANTICIPATED NONE ANTICIPATED NONE ANTICIPATED NONE ANTICIPATED NONE ANTICIPATED NONE ANTICIPATED NONE ANTICIPATED NONE ANTICIPATED NO FLOW OBSERVED NO FLOW OBSERVED NO FLOW OBSERVED NO FLOW OBSERVED NO FLOW OBSERVED INACCESSIBLE Page 25 City of Renton K CATCH BASIN 18" 0 HOPE ©2015 0. R. STRONG Consulting Engineers Inc. Level One Downstream Analysis ±1,624' NONE OBSERVED Alpine Nursery NONE ANTICIPATED THIS rs THE END OF THE QUARTER MILE DOWNSTREAM PATH. RUNOFF CONTINUES SOUTH IN THE CONVEYANCE SYSTEM IN 160'" PLACE SE AND OUTLETS TO CEDAR RIVER APPROXIMATELY 0.5 MILES SOUTH OF THE SITE. Page 26 City of Renton Basin: Cedar__River Symbol Drainage Drainage Component Component Type, Description Name, and Size Type: sheet flow, See map swale, Stream, drainage basin, vegetation, cover, channel, pipe, depth, type of sensitive area, volume Pond; Size: diameter Surface area A NATURAL SOUTH SIDE OF SE 144T" STREET DISCHARGE POINT A-B NORTHWESTERLY NATIVE VEGETATION/ GRASS/SOIL SHEET FLOW B CATCH BASIN -OUTLET 0N) B-C WESTERLY PIPE 18" 0CMP FLOW C CATCH BASIN -INLET (E) -OUTLET 0N) C-D WESTERLY PIPE 18" 0 CMP FLOW D PIPE INLET -INLET (E) -OUTLET 0N) D-E WESTERLY PIPE 18" 0 CMP FLOW E CATCH BASIN -INLET (E) -OUTLET 0N) ©2015 D.R. STRONG Consulting Engineers Inc. Level One Downstream Analysis TOA North Subbasin Number: Lower Cedar River Slope Distance Existing Potential Observations of field inspector From site Problems Problems resource reviewer, or resident Discharae Constrictions, under capacity, ponding, tributary area, likelihood of problem, % 1/4mr-1.320ft overtopping, flooding, habitat or organism overflow pathways, potential impacts. destruction, scouring, bank sloughing, sedimentation, incision, other erosion ±0' NONE NONE OBSERVED ANTICIPATED NONE NONE NO FLOW OBSERVED OBSERVED ANTICIPATED ±19' NONE NONE OBSERVED ANTICIPATED NONE NONE NO FLOW OBSERVED OBSERVED ANTICIPATED ±219' NONE NONE OBSERVED ANTICIPATED NONE NONE FLOW OBSERVED OBSERVED ANTICIPATED ±260' NONE NONE OBSERVED ANTICIPATED NONE NONE FLOW OBSERVED OBSERVED ANTICIPATED ±378' NONE NONE OBSERVED ANTICIPATED Alpine Nursery Page 27 City of Renton E-F F F-G G G-H H H-1 I 1-J J J-K K WESTERLY PIPE 18"0CMP FLOW CATCH BASIN -INLET (E) -OUTLET (!N) WESTERLY PIPE 18" 0 CMP FLOW CATCH BASIN -INLET (E) -OUTLET (!N) WESTERLY PIPE 18" 0 CMP FLOW CATCH BASIN -INLET (E) -OUTLET (!N) WESTERLY PIPE 18" 0 CMP FLOW CATCH BASIN -INLET (E) -OUTLET (!N) WESTERLY PIPE 18" 0CMP FLOW CATCH BASIN -INLET (E) -OUTLET (!N) WESTERLY PIPE 18" 0 CMP FLOW CATCH BASIN -INLET (E) -OUTLET (!N) ©2015 D.R. STRONG Consulting Engineers Inc. Level One Downstream Analysis NONE OBSERVED ±523' NONE OBSERVED NONE OBSERVED ±689' NONE OBSERVED NONE OBSERVED ±832' NONE OBSERVED NONE OBSERVED ±1,009' NONE OBSERVED NONE OBSERVED ±1,188' NONE OBSERVED NONE OBSERVED ±1,360' NONE OBSERVED Alpine Nursery NONE ANTICIPATED NONE ANTICIPATED NONE ANTICIPATED NONE ANTICIPATED NONE ANTICIPATED NONE ANTICIPATED NONE ANTICIPATED NONE ANTICIPATED NONE ANTICIPATED NONE ANTICIPATED NONE ANTICIPATED NONE ANTICIPATED FLOW OBSERVED FLOW OBSERVED FLOW OBSERVED FLOW OBSERVED FLOW OBSERVED FLOW OBSERVED Page 28 City of Renton K-L L WESTERLY PIPE 18" 0 CMP FLOW CATCH BASIN -INLET (E) -OUTLET (NW) ©2015 D.R. STRONG Consulting Engineers Inc. Level One Downstream Analysis NONE OBSERVED ±1.511' NONE OBSERVED Alpine Nursery NONE ANTICIPATED NONE ANTICIPATED FLOW OBSERVED THIS IS THE END OF THE QUARTER MILE DOWNSTREAM. RUNOFF CONTINUES WEST IN THIS CONVEYANCE SYSTEM AND CROSSES 1541 " PLACE SE AND OUTLETS TO STEWART CREEK WHICH OUTLETS TO CEDAR RIVER APPROXIMATELY 0.4 MILES WEST OF THE SITE. Page 29 City of Renton FIGURE 13. DOWNSTREAM MAP ©2015 D.R. STRONG Consulting Engineers Inc. Level One Downstream Analysis Alpine Nursery Page 30 City of Renton VI ' ~ ----/ !:'I !!:! J2 'q; i!: ~ ----------, ~------------__ __J _____ ~-- ' i ' i ' i ' ! ! ! ! i i L_ !:'I it i!: Ill - -------I ----' bl ---------L--,.. % '. -"'-? -a:'<':: "<f> 5£ JONES RD ..:: i!: ~ - --------..,',V:11 i ' i I I I : I I I I 1•~-T--\-r---r--r-r--.r-1 1 r , r I J 1 11 ) I J I f I I I II ,,."' I ' ' I l I I I I I \ ..... 1 , I t I I I I I \ t l--1 __ ...L...._l----1 •. ...L....l __ ~----, ·-t I C "~ t=' ~,-------\(\ K --------- ,,-I I I ---~ I ' i ' i i ' i i ! ! ! . -----____ j @ NORTH GRAPHIC SCALE 0 250 500 750 1 INCH = 500 FT. R: \2014\0\14069\3\Drowings\Plots\PP\Report Flgun!!ts\3DS140f,9.dwg 1/12/2015 8: IJ:2.J AM PST COPYRIGHT @2014, D.R. STRONG CONSULTlNG ENGINEERS INC. m I 11 ;I ~ I ~ ! i· 1 I I i I~ ' ~ 0 ti ~ ~ '<C 1-- Q., ~ s: co :=!l ~i~ ~ ~""~ ~ !§ 1~ l:t: :.!: "" _,.-t;;; !,IJ ,-.. ... ~ ~"ii~ ~ a: 1--;.: ~ ~~~ g ! ~ ~ l5 ,-.. DRAFTED BY: GEN DE'SICNm BY.· PRO.ECT ENGIN££R: MAJ DAT£: 12,16,2014 PROJ£CT NO.: l,wli9 FIGURE: 13 I APPENDIX B. DRAINAGE COMPLAINTS MAP \ "-1 ', '-,~1:. ' ' ' \ "' ,,, ©2015 D.R. STRONG Consulting Engineers Inc. Level One Downstream Analysis Alpine Nursery I '" Page 31 City of Renton (l•)ild) D.R. STRONG CONSUL TING ENGINEERS Geotechnical Engineering Geology Environmental Scientists Construction Monitoring .-~' ) ,:'! • -·-.:.. GEOTECHNICAL ENGINEERING STUDY ALPINE GARDENS PRELIMINARY PLA 16023 SOUTHEAST 144TH STREET RENTON, WASHINGTON ES-3377 PREPARED FOR JAYMARC HOMES June 5, 2014 Stephen H. Avril Staff Geologist Kyle R. Campbell, P.E. Principal GEOTECHNICAL ENGINEERING STUDY ALPINE GARDENS PRELIMINARY PLAT 16023 SOUTHEAST 144th STREET RENTON, WASHINGTON ES-3377 Earth Solutions NW, LLC 1805. 1361h Place Northeast, Suite 201 Bellevue, Washington 98005 Phone: 425-449-4704 Fax: 425-449-4711 Toll Free: 866-336-8710 Important Information About Your Geotechnical Engineering Report Subsurface problems are a pnncipal cause of construct/On delays, cost overruns, claims, and d1sput~s . • The following informal/On is provided to help you manage your nsks. Geotechnical Services Are Performed for Specific Purposes, Persons, and Protects Geotechnical engineers structure their services to meet tile specific needs of their clients. A geotechnical engineering study conducted for a civil engi- neer may not fulfill the needs of a construction contractor or even another civil engineer. Because each geotechnical engineering study is unique, each geotechnical engineering report is unique, prepared sole/yfor the client. No one except you should rely on your geotechnical engineering report without first conferring with the geotechnical engineer who prepared it. And no one -not even you-should apply tile report for any purpose or project except the one originally contemplated. Read the Fall Report Serious problems have occurred because those relying on a geotechnical engineering report did not read it all. Do not rely on an executive summary. Do not read selected elements only. A Geotechnical Engineering Rlort Is Based on A Unique Sat of Project-Spec c Factors Geotechnical engineers consider a number of unique, project-specific fac- tors when establishing the scope of a study. Typical factors include: the client's goals, objectives, and risk management preferences; the general nature of the structure involved, its size, and configuration; the location of the structure on the site; and other planned or existing site improvements, such as access roads, parking lots, and underground utilities. Unless the geotechnical engineer who conducted the study specifically indicates oth- erwise, do not rely on a geotechnical engineering report that was: • not prepared for you, • not prepared for your project, • not prepared for the specific site explored, or • completed before important project changes were made. Typical changes that can erode the reliability of an existing geotechnical engineering report include those that affect: • the function of the proposed structure, as when it's changed from a parking garage to an office building, or from a light industrial plant to a refrigerated warehouse, • elevation. configuration, location, orientation, or weight of the proposed structure, • composition of the design team, or • project ownership. As a general rule, always inform your geotechnical engineer of project changes-€Ven minor ones-and request an assessment of their impact. Geotechnical engineers cannot accept responsibility or liability tor problems that occur because their reports do not consider developments of which they were not informed. Subsurface Conditions Can Change A geotechnical engineering report is based on conditions that existed at the time the study was performed. Do not rely on a geotechnical engineer- ing reportwhose adequacy may have been affected by: the passage of time; by man-made events. such as construction on or adjacent to the site; or by natural events. such as floods, earthquakes. or groundwater fluctua- tions. Always contact the geotechnical engineer before applying the report to determine if it is still reliable. A minor amount of additional testing or analysis could prevent major problems. Most Geotechnical Findings Are Professional Opinions Site exploration identifies subsurface conditions only at those points where subsurface tests are conducted or samples are taken. Geotechnical engi- neers review field and laboratory data and then apply their professional judgment to render an opinion about subsurface conditions throughout the site. Actual subsurface conditions may differ-sometimes significantly- from those indicated in your report. Retaining the geotechnical engineer who developed your report to provide construction observation is the most effective method of managing the risks associated with unanticipated conditions. A Report's Recommendations Are Not Final Do not overrely on the construction recommendations included in your report. Those recommendations are not final, because geotechnical engi- neers develop them principally from judgment and opinion. Geotechnical engineers can finalize their recommendations only by observing actual subsurtace conditions revealed during construction. The geotechnica/ engineer who developed your report cannot assume responsibility or liability for the report's recommendations if that engineer does not perform construction observation. A Geotechnical Engineering Report Is SubJect to Misinterpretation Other design team members' misinterpretation of geotechnical engineering reports has resulted in costly problems. Lower that risk by having your geo- technical engineer confer with appropriate members of the design team after submitting the report. Also retain your geotechnical engineer to review perti- nent elements of the design team's plans and specifications. Contractors can also misinterpret a geotechnical engineering report. Reduce that risk by having your geotechnical engineer participate in prebid and preconstruction conferences, and by providing construction observation. Do Not Redraw the Engineer's Logs Geotechnical engineers prepare final boring and testing logs based upon their interpretation of field logs and laboratory data. To prevent errors or omissions, the logs included in a geotechnical engineering report should never be redrawn for inclusion in architectural or other design drawings. Only photographic or electronic reproduction is acceptable, but recognize that separahng logs from the report can elevate nsk. Give Contractors a Complete Report and Guidance Some owners and design professionals mistakenly believe they can make contractors liable for unanticipated subsurface conditions by limiting what they provide for bid preparation. To help prevent costly problems, give con- tractors the complete geotechnical engineering report, bu/preface it with a clearly written letter of transmittal. In that letter, advise conhactors that the report was not prepared for purposes of bid development and that the report's accuracy is limited; encourage them to confer with the geotechnical engineer who prepared the report (a modest fee may be required) and/or to conduct additional study to obtain the specific types of information they need or prefer. A prebid conference can also be valuable. Be sure con/Jac- tors have sufficient time to perform additional study. Only then might you re in a position to give contractors the best information available to you, white requiring them to at least share some of the financial responsibilities stemming from unanticipated conditions. Read-.Responsibility Provisions CloselJ Some clients, design professionals, and contractors do not recognize that geotechnical engineering is far less exact than other engineering disci- plines. This lack of understanding has created unrealistic expectations that have led to disappointments, claims, and disputes. To help reduce the risk of such outcomes, geotechnical engineers commonly include a variety of explanatory provisions in their reports. Sometimes labeled 'limitations" many of these provisions indicate where geotechnical engineers' responsi- bilities begin and end, to help others recognize their own responsibilities and risks. Read these provisions closely. Ask questions. Your geotechnical engineer should respond fully and frankly. Geoenvironmental Concerns Are Not Covered The equipment, techniques, and personnel used to perform a geoenviron- mental study differ significantly from those used to perform a gcotechn/cat study. For that reason, a geotechnical engineering report does not usually relate any geoenvironmental findings, conclusions, or recommendations; e.g., about the likelihood of encountering underground storage tanks or regulated contaminants. Unanticipated environmental problems have led lo numerous project failures. If you have not yet obtained your own geoen- vironmental information, ask your geotechnical consultant for risk man- agement guidance. Do not rely on an environmental report prepared for someone else. Obta~ Professional Assistance To Deal with Mold Diverse strategies can be applied during building design, construction, operation, and maintenance to prevent significant amounts of mold from growing on indoor surfaces. To be effective, all such strategies should be devised for the express purpose of mold prevention, integrated into a com- prehensive plan, and executed with diligent oversight by a professional mold prevention consultant. Because just a small amount of water or moisture can lead to the development of severe mold infestations, a num- ber of mold prevention strategies focus on keeping building surtaces dry. While groundwater, water infiltration, and similar issues may have been addressed as part of the geotechnical engineering study whose findings are conveyed in-this report, the geotechnical engineer in charge of this project is not a mold prevention consultant none of the services per- formed in connection with the geotechnica/ engineer's study were designed or conducted tor the purpose of mold preven- tion. Proper implementation of the recommendations conveyed in this report will not of itself be sufficient to prevent mold from growing in or on the structure involved. RelY, on Y& ASFE-Membar Geotecbnclal Engineer far Ad•na1 Assistance Membership in ASFE/fhe Best People on Earth exposes geoteclmical engineers to a wide array of risk management techniques that can be of genuine benefit for everyone involved with a construction project. Confer with you ASFE-member geotechnical engineer for more information. ASFE TU 1•11 PIHi• 11 Earlll 8811 Colesville Road/Suite G106, Silver Spring, MO 20910 Telephone: 301/565-2733 Facsimile: 301/589-2017 e-mail: info@asfe.org www.asfe.org Copyright 20Q4 by ASFE, lnc. Dupllcation, reproduction, or copying of this document, In whole or In part by any m,;ins whatsoever, Is stn·ctly prohibited, except with ASFE's specific writtsn permission. Excerpllng, quoting, Of oth9!Wfso ,xtractlng wording from this documtmt is psrmlltld only with the express written permission of ASFE, and oofy for purpoSBS of scholarly Medrch or book review. onry mtmbtlrs of ASFE may use this document as a complBment to or as an element of a geotachnlcal engineering report. Any other firm. lndlvfdual, or othet Bnlily that so us,s Ws docuffl8nt without being ,n ASFE member could be committing negligent or intentional (fraudufent) misreprasentation. IIGER06045.0M June 5, 2014 ES-3377 JayMarc Homes 7525 Southeast 24th Street, Suite 487 Mercer Island, Washington 98040 Attention: Mr. Jay Mezistrano Dear Mr. Mezistrano: Earth Solutions NW LLC • Geotechnical Engineering • Construct.ion Monitoring • Environmental Sciences Earth Solutions NW, LLC (ESNW) is pleased to present this report titled "Geotechnical Engineering Study, Alpine Gardens Preliminary Plat, 16023 Southeast 144th Street, Renton, Washington". In general, the site is underlain primarily by glacial outwash and limited areas of fill surrounding the existing structures and utility alignments. In our opinion, the proposed residential structures can be supported on conventional continuous and spread footing foundations bearing on competent native soil encountered at depths between two to four feet; or structural fill. Groundwater seepage was not observed at any of the test locations. However, seepage should be expected during grading activities, particularly during winter, spring and early summer months. Recommendations for foundation design, site preparation, drainage, and other pertinent recommendations are provided in this study. We appreciate the opportunity to be of service to you on this project. If you have questions regarding the content of this geotechnical engineering study, please call. Sincerely, EARTH SOLUTIONS NW, LLC Stephen H. Avril Staff Geologist 1805 -136th Place N.E., Suite 201 • Bellevue, WA 98005 • (425) 449-4704 • FAX (425) 449-4711 Table of Contents ES-3377 PAGE INTRODUCTION . .. .. . . .. . .. . . . . .. . .. ... .... .. .. . .. . .. . . .. . .. . . . . .. . .. .. . . . . .. . .. .. 1 General ... ............... ... ... ... ...... ............ ... ...... ... ... .......... 1 Project Description........ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 SITE CONDITIONS.................................................................. 2 Surface........................................................................ 2 Subsurface................................................................... 2 Fill..................................................................... 3 Topsoil............................................................... 3 Native Soil .. . .. . .. . .. . .. . .. . .. . .. .. . .. .. . .. .. ... . .. .. .. . . .. .. ....... 3 Geologic Setting..................................................... 3 Groundwater................................................................. 3 DISCUSSION AND RECOMMENDATIONS.................................. 4 General........................................................................ 4 Site Preparation and General Earthwork........................... 4 Wet Season Grading............................................. 5 In-situ Soils..................................................................... 5 Imported Soils................................................................ 5 Structural Fill.................................................................. 6 Foundations .. . . . . .. . .. .. .. .. .. .. . .. .. . . .. . .. .. .. .. . .. .. .. .... .. . . . .. . .. . .. . 6 Seismic Design Considerations...................................... 6 Slab-On-Grade Floors.................................................... 7 Retaining Walls............................................................. 7 Drainage.................................................................................... 8 Excavations and Slopes........................................................... 9 Utility Trench Backfill..................................................... 9 Pavement Sections .. . .. .. .. . .. . .. . .. . .. . .. . .. . . .. .. .. .. .. .. .. .. .. . .. .. .... 9 LIMITATIONS......................................................................... 10 Additional Services....................................................... 10 Earth Solutions NW, LLC GRAPHICS Plate 1 Plate 2 Plate 3 Plate 4 APPENDICES Appendix A Appendix B Table of Contents Cont'd ES-3377 Vicinity Map Test Pit Location Plan Retaining Wall Drainage Detail Footing Drain Detail Subsurface Exploration Test Pit Logs Laboratory Test Results Earth Solutions NW, LLC General GEOTECHNICAL ENGINEERING STUDY ALPINE GARDENS PRELIMINARY PLAT 16023 SOUTHEAST 144th STREET RENTON, WASHINGTON ES-3377 INTRODUCTION This geotechnical engineering study was prepared for the proposed residential development to be constructed on the south side of Southeast 144th Street in Renton, Washington. The site is comprised of three tax parcels; and is located south of Southeast 144th Street, between 160th Avenue Southeast and 161"1 Avenue Southeast. The purpose of this study was to develop geotechnical recommendations for the proposed development. Our scope of services for completing this geotechnical engineering study included the following: • Reviewing the project details; • Excavation, logging and sampling oftest pits excavated at the site; • Engineering analyses of data obtained through the site exploration, and; • Preparation of this report. The following documents/maps were reviewed as part of our report preparation: • Conceptual Site Plan -Option C, by ESM Consulting Engineers, LLC., Sheet PL-03, dated April 18, 2014; • King County iMap online resource; • Geologic Map of Washington, Southwest Quadrant, by Walsh, et al, 1987, and; • Washington State USDA Soil Conservation Survey (SCS). JayMarc Homes June 5, 2014 Project Description ES-3377 Page 2 We understand the site will be developed with 30 single-family residential structures, on-site roadways, parking areas, and associated improvements. Grading plans were not available at the time of this report production; however, given the topographic change across the site, we anticipate grading activities will likely involve cuts and fills on the order of eight feet or less to establish the final design grades. Final building loads were not available at the time of our report. However, we anticipate wall loads for one to two-story single-family residential structures will be on the order of 1 to 2 kips per lineal foot; and slab-on-grade loading of 150 pounds per square foot (psf). A stormwater pond is proposed to be located on the south side of the site. Design parameters were not available at the time of report production for the pond. If the above design estimates are incorrect or change, ESNW should be contacted to review the recommendations in this report. ESNW should review the final design to confirm that our geotechnical recommendations have been incorporated into the final design. SITE CONDITIONS Surface The site is located on the south side of Southeast 144th Street, and east of 160th Avenue Southeast in Renton, Washington. The approximate location of the property is illustrated on Plate 1 (Vicinity Map). The site is roughly rectangular in shape and consists of three tax parcels. The majority of the site is currently developed with a plant nursery. Green belts and several single-family residences are also located on the subject site within the proposed development envelope. The existing site topography descends very gently from the street elevation towards the south; with elevation change on the order of approximately 15 feet. Vegetation consisted primarily of grassy landscaped areas located between planter strips and greenhouses. ESNW observed second-growth fir and cedar trees on the site periphery during our fieldwork. Subsurface A representative of ESNW observed, logged and sampled seven test pits excavated with a track-hoe across the site. The test pits were excavated for the purposes of characterizing the subsurface conditions. The approximate locations of the test pits are depicted on the Test Pit Location Plan (Plate 2). Please refer to the test pit logs provided in Appendix A for a detailed description of the subsurface conditions. Earth Solutions NW, LLC JayMarc Homes June 5, 2014 Fill ES-3377 Page 3 Fill was encountered at test pit location TP-4, located in the southern portion of the site. Fill soil should be anticipated surrounding the existing residential structures and outbuildings throughout the site. The fill was observed to extend to three and one half feet below existing grades. The silty sand with gravel (Unified Soil Classification, SM) fill may be suitable for support of foundations; however a representative of ESNW should be retained during the construction phases of the site development to evaluate the suitability of any on-site soils for use as structural fill or bearing of foundations. Topsoil Topsoil was encountered at all but one of the test pit locations extending to depths of between about two to six inches below existing grade. Topsoil is not suitable for use as structural fill nor should it be mixed with material to be used as structural fill. Topsoil or otherwise unsuitable material can be used in landscaping areas if desired. Native Soil Underlying the topsoil and fill, native soil consisting primarily medium dense to dense glacial outwash consisting of poorly graded sand with silt and gravel (SP) was encountered extending to the maximum exploration depth of five feet below existing grades. The native soil consisted of silty sand with gravel (SM); and poorly graded sand with silt and gravel (SP). The native soil transitioned from a medium dense condition to dense at approximately three feet in depth at most of the test pit locations. Geologic Setting The referenced geologic map resource identifies glacial outwash (Qgo) deposits across the site and surrounding areas. The referenced SGS soil survey identifies Everett Gravelly Sandy Loam (EvB) series soils across the site and surrounding area. Everett gravelly sandy loam soils consist of glacial outwash formed on terraces and typically present a low to moderate erosion hazard; and are somewhat excessively drained. The soil conditions observed at the test pit locations are generally consistent with glacial outwash deposits. Groundwater Groundwater was not observed at any of the test pit locations during the fieldwork (May 2014). However, seepage should be expected at some locations, particularly during the winter, spring and early summer months. Groundwater seepage rates and elevations fluctuate depending on many factors, including precipitation duration and intensity, the time of year, and soil conditions. In general, groundwater flow rates are higher during the wetter, winter months. Earth Solutions NW, LLC JayMarc Homes June 5, 2014 DISCUSSION AND RECOMMENDATIONS General ES-3377 Page4 In our opinion, construction of the proposed residential development is feasible from a geotechnical standpoint. The proposed buildings can be supported on conventional continuous and spread footing foundations bearing on competent native soil, existing competent fill or at least two feet of structural fill. Slab-on-grade floors should be supported on a firm and unyielding subgrade. Recommendations for foundation design, site preparation, drainage, and other pertinent geotechnical recommendations are provided in the following sections of this study. This study has been prepared for the exclusive use of JayMarc Homes and their representatives. No warranty, expressed or implied, is made. This study has been prepared in a manner consistent with the level of care and skill ordinarily exercised by other members of the profession currently practicing under similar conditions in this area. Site Preparation and Earthwork Site preparation activities will involve removal of existing structures, site clearing and stripping, and implementation of temporary erosion control measures. The primary geotechnical considerations associated with site preparation activities include building pad subgrade preparation, underground utility installations, and preparation of pavement subgrade areas. Temporary construction entrances and drive lanes, consisting of at least 12 inches of quarry spalls can be considered in order to minimize off-site soil tracking and to provide a stable access entrance surface. Erosion control measures should consist of silt fencing placed along the down gradient side of the site. Soil stockpiles should be covered or otherwise protected to reduce soil erosion. Temporary sedimentation ponds or other approaches for controlling surface water runoff should be in place prior to beginning earthwork activities. Topsoil and organic-rich soil was encountered generally within the upper six to eight inches at the test pit locations. Topsoil and organic-rich soil is not suitable for direct foundation support, nor is it suitable for use as structural fill. Topsoil or organic-rich soil can be used in non- structural areas if desired. A representative of ESNW should observe the initial stripping operations, to provide recommendations for stripping depths based on the soil conditions exposed during stripping. Subgrade conditions expected to be exposed throughout the proposed building and pavement areas will likely be comprised of poorly graded sand with silt and gravel glacial deposits. After the completion of site stripping the subgrade conditions should be evaluated by a representative of ESNW. A proofroll utilizing a fully loaded solo dump truck may be necessary to evaluate the suitability of the exposed native soils prior to placement of fill. ESNW should be retained during this phase of earthwork to observe the subgrade conditions and other earthwork activities. The soils exposed throughout subgrade areas should be compacted to structural fill specifications prior to constructing the foundation, slab, and pavement elements. The subgrade throughout pavement areas should be compacted as necessary and exhibit a firm and unyielding condition when subjected to the proofrolting with a loaded solo dump truck. Earth Solutions NW, LLC JayMarc Homes June 5, 2014 ES-3377 Page 5 Overexcavation and replacement with crushed rock may be necessary, depending on the conditions encountered during construction. Structural fill soils placed throughout foundation, slab, and pavement areas should be placed over a firm base. Loose or otherwise unsuitable areas of native soil exposed at subgrade elevations should be compacted to structural fill requirements or overexcavated and replaced with a suitable structural fill material. Where structural fill soils are used to construct foundation subgrade areas, the soil should be compacted to the requirements of structural fill described in the following section. Foundation subgrade areas should be protected from disturbance, construction traffic, and excessive moisture. Where instability develops below structural fill areas, use of a woven geotextile below the structural fill areas may be required. A representative of ESNW should observe structural fill placement in foundation, slab, and pavement areas. Wet Season Grading The moderate moisture sensitivity of the on-site soil will make grading during periods of rain somewhat difficult. Mass grading should take place during the late summer months when conditions are more favorable. If grading takes place during the wetter winter, spring or early summer months, a contingency in the project budget should be included to allow for export of native soil and import of structural fill as described below. In-situ Soils The soils encountered throughout the majority of the test sites have a moderate sensitivity to moisture and were generally in a moist condition at the time of the exploration (May 2014). In this respect, the in-situ soils may not be suitable for use as structural fill if the soil moisture content is more than 4 to 5 percent above the optimum level at the time of construction in the case of the silty sand and poorly graded sand with silt soil encountered at a number of the test pit locations. In general, soils encountered during the site excavations that are excessively over the optimum moisture content will require moisture conditioning prior to placement and compaction. Conversely, soils that are below the optimum moisture content will require moisture conditioning through the addition of water prior to use as structural fill. If the in-situ soils are determined to not be suitable for use as structural fill, then use of a suitable imported soil may be necessary. In our opinion, a contingency should be included in the project budget for exporting unsuitable soil and importing structural fill; or moisture conditioning recommendations can be provided upon request based on field observations during the construction phase of on-site work. Imported Soils Imported soil intended for use as structural fill should consist of a well graded granular soil with a moisture content that is at or near the optimum level. During wet weather conditions, imported soil intended for use as structural fill should consist of a well graded granular soil with a fines content of 5 percent or less defined as the percent passing the #200 sieve, based on the minus three-quarter inch fraction. Earth Solutions NW, LLC JayMarc Homes June 5, 2014 Structural Fill ES-3377 Page 6 Structural fill is defined as compacted soil placed in foundation, slab-on-grade, and roadway areas. Fills placed to construct permanent slopes and throughout retaining wall and utility trench backfill areas are also considered structural fill. Soils placed in structural areas should be placed in loose lifts of 12 inches or less, at moisture contents above the optimum level and compacted to a relative compaction of 90 percent, based on the laboratory maximum dry density as determined by the Modified Proctor Method (ASTM D-1557). Soil placed in utility trenches, pavement areas and in the upper 12 inches of slab-on-grade areas should be compacted to a relative compaction of at least 95 percent. Additionally, more stringent compaction specifications may be required for utility trench backfill zones, depending on the responsible utility district or jurisdiction. Foundations Based on the results of our study, the proposed residential buildings can be supported on conventional spread and continuous footings bearing on competent native soils encountered between two and four feet below existing grades, competent existing fill or new structural fill. Loose soil exposed at foundation subgrade elevations can be compacted in-place. Provided foundations are be supported as described above, the following parameters can be used for design of new foundations: • Allowable soil bearing capacity • Passive earth pressure • Coefficient of friction 2,500 psf 300 pcf (equivalent fluid) 0.40 A one-third increase in the allowable soil bearing capacity can be assumed for short-term wind and seismic loading conditions. The above passive pressure and friction values include a factor-of-safety of 1.5. With structural loading as expected, total settlement in the range of one and one half inch and differential settlement of about one inch is anticipated. The majority of the settlements should occur during construction, as dead loads are applied. Seismic Design Considerations The 2012 !BC recognized the American Society of Civil Engineers (ASCE) for seismic site class definitions. In accordance with Table 20.1-1 of the ASCE Minimum Design Loads for Buildings and Other Structures manual, Site Class D should be used for design. Liquefaction is a phenomenon where saturated or loose soils suddenly lose internal strength in response to increased pore water pressures resulting from an earthquake or other intense ground shaking. The referenced liquefaction susceptibility map of King County indicates the site and surrounding areas exhibit a very low to low liquefaction susceptibility. Earth Solutions NW, LLC JayMarc Homes June 5, 2014 ES-3377 Page 7 In our opinion, site susceptibility to liquefaction can be characterized as low. The absence of a uniformly established shallow groundwater table is the primary basis for this characterization. Slab-On-Grade Floors Slab-on-grade floors for residential buildings constructed at this site should be supported on a firm and unyielding subgrade. Where feasible, the existing native soils exposed at the slab-on- grade subgrade level can be compacted in place to the specifications of structural fill. Unstable or yielding areas of the subgrade should be recompacted or overexcavated and replaced with suitable structural fill prior to construction of the slab. A capillary break consisting of a minimum of four inches of free draining crushed rock or gravel should be placed below the slab. The free draining material should have a fines content of 5 percent or less (percent passing the #200 sieve, based on the minus three-quarter inch fraction). In areas where slab moisture is undesirable, installation of a vapor barrier below the slab should be considered. If a vapor barrier is to be utilized it should be a material specifically designed for use as a vapor barrier and should be installed in accordance with the manufacturer's specifications. Retaining Walls Retaining walls must be designed to resist earth pressures and applicable surcharge loads. The following parameters can be used for retaining wall design: • Active earth pressure (yielding condition) 35 pcf (equivalent fluid) • At-rest earth pressure (restrained condition) 55 pcf • Traffic surcharge for passenger vehicles 70 psf (rectangular distribution) (where applicable) • Passive earth pressure 300 pcf (equivalent fluid) • Coefficient of friction O .40 • Seismic surcharge (active condition) 6H* • Seismic surcharge (restrained condition) 14H* *where H equals retained height Additional surcharge loading from adjacent foundations, sloped backfill, or other loads should be included in the retaining wall design. Drainage should be provided behind retaining walls such that hydrostatic pressures do not develop. If drainage is not provided, hydrostatic pressures should be included in the wall design. Earth Solutions NW, LLC JayMarc Homes June 5, 2014 ES-3377 Page 8 Retaining walls should be backfilled with free draining material that extends along the height of the wall, and a distance of at least 18 inches behind the wall. The upper one foot of the wall backfill can consist of a less permeable soil, if desired. A perforated drain pipe should be placed along the base of the wall, and connected to an approved discharge location. A typical retaining wall drainage detail is provided on Plate 3. Drainage Groundwater was not observed during the fieldwork (May 2014). However, groundwater should be anticipated in deeper site excavations particularly during the wetter winter and early spring months. Temporary measures to control surface water runoff and groundwater during construction would likely involve interceptor trenches and sumps. ESNW should be consulted during preliminary grading to identify areas of seepage and to provide recommendations to reduce the potential for instability related to seepage effects. Infiltration of stormwater runoff from downspouts and roadways is feasible on the subject site, given the subsurface conditions ESNW observed at the test pit locations. However, further infiltration testing will be required to provide the allowable rates of infiltration in accordance with local and state regulations. In our opinion, foundation drains may not be necessary if free-draining sand is exposed in foundation excavations. A representative of ESNW should observe the foundation excavations during construction to evaluate the need for foundation drains. A typical foundation drain detail is provided as Plate 4. Excavations and Slopes The Federal Occupation Safety and Health Administration (OSHA) and the Washington Industrial Safety and Health Act (WISHA) provide soil classification in terms of temporary slope inclinations. Based on the soil conditions encountered at the hand hole locations, the soils encountered within the majority of the development envelope, and where groundwater seepage is exposed, are classified as Type C by OSHA/WISHA. Temporary slopes over four feet in height in Type C soils must be sloped no steeper than 1.5H:1V (Horizontal:Vertical). The presence of perched groundwater may cause caving of the temporary slopes due to hydrostatic pressure. ESNW should observe site excavations to confirm the soil type and allowable slope inclination. If the recommended temporary slope inclination cannot be achieved, temporary shoring may be necessary to support excavations. Permanent slopes should maintain a gradient of 2H:1V, or flatter, and should be planted with vegetation to enhance stability and to minimize erosion. A representative of ESNW should observe temporary and permanent slopes to confirm the slope inclinations, and to provide additional excavation and slope recommendations, as necessary. Earth Solutions NW, LLC JayMarc Homes June 5, 2014 Utility Support and Trench Backfill ES-3377 Page 9 In our opinion, the soils anticipated to be exposed in utility excavations should generally be suitable for support of utilities. Organic or highly compressible soils encountered in the trench excavations should not be used for supporting utilities. Some of the native soils are moisture sensitive and will therefore be difficult to use as structural trench backfill if the moisture content of the soil is high. Moisture conditioning of the soils will likely be necessary prior to use as structural backfill. Utility trench backfill should be placed and compacted to the specifications of structural fill provided in this report, or to the specifications of the applicable jurisdiction. Seepage should be anticipated within utility trench excavations. Caving of the trench sidewalls due to hydrostatic pressure or the cohesionless nature of the site soils should be anticipated by the contractor. Pavements The performance of site pavements is largely related to the condition of the underlying subgrade. To provide adequate pavement performance, the subgrade should be in a firm and unyielding condition when subjected to proofrolling with a loaded dump truck. Structural fill in pavement areas should be compacted as recommended in the "Site Preparation and Earthwork" section of this report. It is possible that soft, wet, or otherwise unsuitable subgrade areas may still exist after base grading activities. Areas of unsuitable or yielding subgrade conditions will require remedial measures such as overexcavation, placement of a geotextile and thicker crushed rock or structural fill sections prior to pavement. For lightly loaded pavement areas subjected primarily to passenger vehicles, the following preliminary pavement sections can be considered: • Two inches of hot-mix asphalt (HMA) placed over four inches of crushed rock base (CRB), or; • Two inches of HMA placed over three inches of asphalt treated base (ATB). The HMA, ATB and CRB materials should conform to WSDOT specifications. All soil base material should be compacted to at least 95 percent of the maximum dry density. Final pavement design recommendations can be provided once final traffic loading has been determined. If areas of seepage are exposed in roadway excavations, drains should be installed in these areas to allow removal of the water. Specific recommendations and details for roadway drainage can be provided upon request. Earth Solutions NW. LLC JayMarc Homes June 5, 2014 LIMITATIONS ES-3377 Page 10 The recommendations and conclusions provided in this geotechnical engineering study are professional opinions consistent with the level of care and skill that is typical of other members in the profession currently practicing under similar conditions in this area. A warranty is not expressed or implied. Variations in the soil and groundwater conditions observed at the test locations may exist, and may not become evident until construction. ESNW should reevaluate the conclusions in this geotechnical engineering study if variations are encountered. Additional Services ESNW should have an opportunity to review the final design with respect to the geotechnical recommendations provided in this report. ESNW should also be retained to provide testing and consultation services during construction. Earth Solutions NW, LLC Reference: King County, Washington Map 657 By The Thomas Guide Rand McNally 32nd Edition NOTE: This plate may contain areas of color. ESNW cannot be , responsible for any subsequent misinterpretation of the information I resulting from black & white reproductions of this plate. Drwn. GLS Checked SSR } -~-11 llffl Vicinity Map Alpine Gardens King County, Washington Date 05/21/2014 Proj. No. 3377 Date May 2014 Plate 1 19 ___ I I I "--__ _L ___ L __ l __ J I "--_ L _ -. <.:._J . I 11 l I I <.:. I R II. I 1--1 I~ 01----:~---r-~--I r---- : : :1 ~!TP~; :11 : ~ TP-61~ I ! I !i :f]fJ·n-. ! i: r-~-j~Ti :---- 1-_J-1 !-01 1JU;tfj~-im---;/ L----:; r-:--i 15 / _/J:J'i' !;J,/ ---! ~ ~----b __ ;~-8~g't1/ :!.!:::!/ ____ _ l::::"I 3[;:jJ I / 1..;_;I I,..,. I L A .... r--T-- i < 1--tJc--! -:._.:-··o I <: I 1:.....1415 1617 :01 i 0 300 --- 1 ~~ __ I __ I ___ I __ __,\ -£ \__ __ _J_ __ _ Scale in Feet I I ---t- / I I i-------1 ---1 --\---, I 22 I I 25 I I _j23 1 24\ I 1-----I I -\ \ l 1----- 1 I 21 1----\ 26 ~, I hP-4 I \-----I I 20 I ,.,· . \ f"':::-, I I TP-2 -~ ---'j . L.....:'.'..J 1 l T•-•'\ -· 1'-------·· -: , TP-3 1 -rr --1 11 -_ J 11 1 \ 28 , I ..l+,-o-1 l 18 I 19 Tl'flfi11 I Storm Pond \\------\ Scale 1" = 150' ( I I I I \----! 1 -. 1 1 -Approximate Location of 1 f P-1 ESNWTest Pit, Proj. No. 1 ES-3377, May 2014 LEGEND \ I :---I Subject Site '----'---- 27 Proposed Lot Number I I O \I 29 \ I-__ 1--e:n 1\ ______ -·\ I \ \ ( I D Existing Building I I 1\ 30 ----~ \ ____ ,..,.._),_ ---\ ----------------\ NOTE: The graphics shown on lhis plate are nol intended for design purposes or precise scale measuremenls, but only lo illustrate the approximate test locations relative to the approximate locations of existing and I or proposed site features. The information illustrated is largely based on data provided by the client at the time of our study. ESNW cannot be responsible for subsequent design changes or interpretation of the data by others. Drwn. GLS I \ NOTE: This plate may contain areas of color. ESNW cannot be responsible for any subsequent misinterpretation of the information resulting from black & white reproductions of this plate. Checked SSR I I ---'-- \ Test Pit Location Plan Alpine Gardens King County, Washington Date 05/2112014 Proj. No. 3377 Date May 2014 Plate 2 .. 18" Min . 111 111 111 QOQooO 0 00 00 o Oo cO o .D o oO o O ooQ O 0° 0 o() 0 0 0 o O ooO°Qo (j 0 0 ° oOooQ 0 c, Oo oo oO o 0 0 00000 OQo 00 0 00000000 0 0 O o o,:() 0 0 0 o 6 o oo O O O Q 0 f; 0 ° 0 -0 0 0 oo OoOoo O Q 0 o 0 ooo00o00 0 0 0 0 Oo o O O o () o o o Oo oo (t O 8 o o 0°0 o Oo o O o Q 0 0 £1 0 0 0 0 o V 0 0 o O o 0 o c, 0 0 0 0 0 0 0 Q 00 oo 0 o O oO O o O CJ 00 O c, 0 o O 0 C>,; o o o o o o o o oo o o B o o -o O 0 ooQO 0000g ooo o 0 c, OQo o 0 0 0 0 Oo O Q 0 ooo O O O O 0 o OooQ oo c, oQ O O o o_ 0 ° o ooo~ oO O O O ()e, 0 0 0 ,9 £70 O e o O Oo°o O°o 0 NOTES: • Free Draining Backfill should consist of soil having less than 5 percent fines. Percent passing #4 should be 25 to 75 percent. Structural Fill • Sheet Drain may be feasible in lieu of Free Draining Backfill, per ESNW recommendations. SCHEMATIC ONLY-NOTTO SCALE NOT A CONSTRUCTION DRAWING • Drain Pipe should consist of perforated, rigid PVC Pipe surrounded with 1" Drain Rock. LEGEND: Free Draining Structural Backfill 1 inch Drain Rock RETAINING WALL DRAINAGE DETAIL Alpine Gardens King County, Washington Drwn. GLS Date 05/27/2014 Proj. No. 3377 Checked SSR Date May 2014 Plate 3 Slope . . . . . . . . ' ... . . . . . . . . . . . . . . . . . . ...... .. 2" (Min.) Perforated Rigid Drain Pipe (Surround with 1" Rock) NOTES: • Do NOT tie roof downspouts to Footing Drain. • Surface Seal to consist of .,. . .,. . .,. ...... ............. rl'•rl'•r/'• ..... ............. ,l'•rl'•rl'•rl'•rl' ............. 12" of less permeable, suitable soil. Slope away from building. LEGEND: Surface Seal; native soil or other low permeability material. 1" Drain Rock SCHEMATIC ONLY-NOTTO SCALE NOT A CONSTRUCTION DRAWING Drwn. GLS FOOTING DRAIN DETAIL Alpine Gardens King County, Washington Date 05/27/2014 Proj. No. 3377 Checked SSR Date May 2014 Plate 4 Appendix A Subsurface Exploration ES-3377 The subsurface conditions at the site were explored by excavating a total of seven test pits excavated across accessible portions of the property. The subsurface explorations were completed in May of 2014. The approximate test pit locations are illustrated on Plate 2 of this report. Logs of the test pits are provided in this Appendix. The test pits were excavated to a maximum depth of 11 feet below existing grades. Earth Solutions NW, LLC Earth Solutions NWLLc SOIL CLASSIFICATION CHART MAJOR DIVISIONS SYMBOLS TYPICAL GRAPH LETTER DESCRIPTIONS COARSE GRAINED SOILS MORE THAN 50% OF MATERIAL IS LARGER THAN NO. 200 SIEVE SIZE FINE GRAINED SOILS MORE THAN 50% OF MA TERI ALIS SMALLER THAN NO. 200 SIEVE SIZE GRAVEL AND GRAVELLY SOILS MORE THAN 50% OF COARSE FRACTION RETAINED ON NO. 4SIEVE SAND AND SANDY SOILS CLEAN GRAVELS ILITILE OR NO FINES) GRAVELS WITH FINES (APPRECIABLE AMOUNT OF FINES) CLEAN SANDS (LITTLE OR NO FINES) SANDS WITH MORE THAN 50% FINES OF COARSE FRACTION PASSING ON NO. 4 SIEVE (APPRECIABLE SILTS AND CLAYS SILTS AND CLAYS AMOUNT OF FINES) LIQUID LIMIT LESS THAN 50 LIQUID LIMIT GREATER THAN SO HIGHLY ORGANIC SOILS GW WELL-GRADED GRAVELS, GRAVEL - SAND MIXTURES, LITTLE OR NO FINES POORLY-GRADED GRAVELS, GP GRAVEL-SAND MIXTURES, LITTLE OR NO FINES GM SILTY GRAVELS, GRAVEL-SAND- SILT MIXTURES GC CLAYEY GRAVELS, GRAVEL-SAND- CIA Y MllCTURES SW WELL-GRADED SANDS, GRAVEL!. Y SANOS, LITTLE OR NO FINES SP POORLY-GRADED SANDS. GRAVELLY SAND, LITTLE OR NO FINES SM SILTY SANOS. SAND-SILT MIXTURES SC CLAYEY SANDS. SANO-CLAY MIXTURES INORGANIC SIL TS AND VERY FINE ML SANOS, ROCK FLOUR, SILTY OR CLAYEY FINE SANOS OR CLAYEY SILTS WITH SLIGHT PLASTICITY INORGANIC CIA YS OF LOW TO CL MEDIUM PLASTICITY, GRAVELLY CLAYS, SANDY CLAYS, SILTY CIA VS, LEAN CIA YS OL ORGANIC SILTS ANO ORGANIC SIL TY CLAYS OF LOW PLASTICITY MH INORGANIC SILTS, MICACEOUS OR OIATOMACEOUS FINE SAND OR SILTY SOILS CH INORGANIC CIA YS OF HIGH PLASTICITY OH ORGANIC CIA YS OF MEDIUM TO HIGH PLASTICITY, ORGANIC SILTS PT PEAT, HUMUS, SWAMP SOILS WITH HIGH ORGANIC CONTENTS DUAL SYMBOLS are used to indicate borderline soil classifications. The discussion in the text of this report is necessary for a proper understanding of the nature of the material presented in the attached logs. :,: s g !3 i ~ ~ ~ ~ a ~ I • Earth Solutions NW 1805 -136th Place N.E., Suite 201 Bellevue, Washington 98005 Telephone: 425-449-4704 Fax: 425-449-4711 TEST PIT NUMBER TP-1 PAGE 1 OF 1 CLIENT Jay Marc Homes . ···-----PROJECT NAME ~A~l"pi~n~e~G~a~rd~e~n~•---------------I l-'-P_R=O.:.JE::CT::.:..:.:Nc:U.::M:.:B:..:E::.R~3=3=7=7===============~..:P~OJECT LOCATION ~ CountyLWashinglon DATESTARTED ~5~/1~3/~1~4~---COMPLETED ~5=/~13=/~14~---GROUND ELEVATION -----·· TEST PIT SIZE __ _ EXCAVATION CONTRACTOR ~N~W~E=x=c=a~va=t=in-g _______ ..... GROUND WATER LEVELS: EXCAVATION METHOD----------------AT TIME OF EXCAVATION ---------_______ 1 LOGGED BY ~S=H~A~-----CHECKED BY ~S=H~A~---AT END OF EXCAVATION --------------- AFTER EXCAVATION -------------------NOTES Depth of Topsoil & Sod 8": bare soil TESTS 0 u.i ci u.i ::, MATERIAL DESCRIPTION TOPSOIL -MC= 12.00% ~ 1 TPSL,, ,11, 1--+-·~·--'=·o~------~------------------------· ·-·--Brown silty SAND with gravel, loose, moist -' f-• f-- MC= 3.80% Fines= 1 o. 70% MC= 3.50% SM SP I 3.0 a.o -iron oxide staining Brown poorly graded SAND with gravel, dense, moist Test pit terminated at 8.0 feet below exlsting grade. No groundwater encountered during excavation. Bottom of test pit at 8.0 feet. '---.1.--.1-------'---'---'---------------------------' • Earth Solutions NW TEST PIT NUMBER TP-2 1805 -136th Place N.E., Suite 201 PAGE 1 OF 1 Bellevue, Washington 98005 Telephone; 425-449-4704 Fax: 425-449-4711 CLIENT _,@}'. Marc Homes PROJECT NAME ~ine Gardens PROJECT NUMBER 3377 PROJECT LOCATION King Count!'., Washington ------------· DATE STARTED 5113114 COMPLETED 5113/14 GROUND ELEVATION TEST PIT SIZE EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS: EXCAVATION METHOD AT TIME OF EXCAVATION ----~-"" LOGGED BY SHA CHECKED BY SHA AT END OF EXCAVATION -··- NOTES Depth of Topsoil & Sod 6": bare soil AFTER EXCAVATION -- w Q. 0 :,: ~ ffi u; 5:~ wm 0 j; Cl TESTS "-o MATERIAL DESCRIPTION w--'::;; u; c2-' 0 Q.::, :;; ::.z Cl < ' en 0 lfPSL Ll ~ 0.5 TOPSOIL Brown silty SAND with gravel, loose, moist " SM -iron oxide staining f- MC= 3.80% 2.5 Brown poorly graded SAND with gravel, dense, moist f-" \ I . SP _L I \ -slight caving MC= 22.40% 5.5 Fines= 41.50% Brown I gray silty SAND with gravel, dense, moist -" " -SM -" MC=3.00% _jQ_ 11.0 ------Test pit terminated at 11.0 feet below existing grade. No groundwater encountered during excavation. Bottom of test pit at 11.0 feet. • Earth Solutions NW TEST PIT NUMBER TP-3 1805 -136th Place N.E., Suite 201 Bellewe, Washington 98005 PAGE 1 OF 1 Telephone: 425-449-4704 Fax: 425-449-4711 CLIENT Ja~ Marc Homes --------· PROJECT NAME j\_lpine Gardens ·-- PROJECT NUMBER 3377 PROJECT LOCATION King County, Washington DATE STARTED 5113114 COMPLETED 5113/14 GROUND ELEVATION TEST PIT SIZE - EXCAVATION CONTRACTOR _ NW Excavating___ GROUND WATER LEVELS: EXCAVATION METHOD ATTIME OF EXCAVATION - LOGGED BY SHA CHECKED BY SHA AT END OF EXCAVATION ... NOTES OeRth of To~soil & Sod 6": grass AFTER EXCAVATION - w Q. 0 :r ~ffi ,,; h'. a= UJ"' ti j; Cl TESTS o.o MATERIAL DESCRIPTION U,J-..J::;; (/) ~...I C 0.:::, :j :ii z Cl en 0 TPSL ,,r,. ,• TOPSOIL -0.5 Brown poorly graded SANO with silt and gravel, dense, moist . MC= 3.70% . . SP- . SM . -becomes fine grained _L 5.0 Test pit terminated at 5.0 feet below existing grade. No groundwater encountered during excavation. Bottom of test pit at 5.0 feet. i= I .. ~ .. .. " .. • Earth Solutions NW 1805 -136th Place N.E., Suite 201 Bellevue, Washington 98005 Telephone: 425-449-4704 Fax: 425-449-4711 CLIENT Jay Marc Homes TEST PIT NUMBER TP-4 PAGE 1 OF 1 PROJECT NUMB_::E:::R~3=3=77~==============~.:_P.:_R::O::J::E:::C:.:T_.L:::O::C:::A~T:::IO~N-=K=inc,;gecC"co'=u=n=ty~,='W=as=h=in~n·to=n==··~-~-=======l DATE STARTED ~5ecl..e13ecl,c14e-___ COMPLETED _,5ecl..e13ecl_,c14e-___ GROUND ELEVATION ·-----TEST PIT SIZE ------ EXCAVATION CONTRACTOR ..,N~W=E:,x,,c,,a.,,vae,te.in,,,g _______ _ GROUND WATER LEVELS: EXCAVATION METHOD---------------AT TIME OF EXCAVATION -·=-------------- LOGGED BY .~S~H~A~-----CHECKED BY _,S,,,H.eA.,__ __ _ AT END OF EXCAVATION..:::;:.._ ___________ _ NOTES Depth of Topsoil & Sod 8": field grass AFTER EXCAVATION w :c ~ ffi li: 47 wlD w-_J:;; 0 a. ::, :;; z TESTS MATERIAL DESCRIPTION <( "' 0 TPSL ~ ~ o.5 TOPSOIL Brown silty SAND with gravel, medium dense, moist (Fill-Asphalt Debris) - SM MC= 14.40% -end fill -native contact . _L 5.0 - MC= 7.10% -. SP - -. MC= 3.70% -1..Q_ 10.0 Brown poorly graded SAND with silt and gravel, dense, moist -decreasing fines, becomes more coarse grained Test pit terminated at 10.0 feet below existing grade. No groundwater encountered during excavation. Bottom oftest pit at 10.0 feet. z w e,·L__.J... __ J_ ______ J__J..._L. ______________________________ __, • Earth Solutions NW TEST PIT NUMBER TP-5 1805 -136th Place N.E., Suite 201 PAGE 1 OF 1 Bellevue, Washington 98005 Telephone: 425-449-4704 Fax: 425-449-4711 CLIENT Jay Marc Homes PROJECT NAME Alpine Gardens --~------- PROJECT NUMBER 3377 PROJECT LOCATION King County, Wash[l_ston ··-----·· .•. -· ----. DATE STARTED 5113/14 COMPLETED 5113/14 GROUND ELEVATION TEST PIT SIZE -- EXCAVATION CONTRACTOR NW Excavating ·-··-GROUND WATER LEVELS: EXCAVATION METHOD AT TIME OF EXCAVATION LOGGED BY SHA CHECKED BY SHA AT END OF EXCAVATION NOTES Dei;i;th ofTo~soil & Sod 6": grass AFTER EXCAVATION w 0. :r 1'= ffi ui 0 :i: (!) ti:~ w Ill TESTS (.) o.o MATERIAL DESCRIPTION w-_,:. ui ~_, 0 o.:::, ::i :.z (!) <( "' 0 iTPSL '-' 0.5 TOPSOIL Brown poorly graded SANO with silt and gravel, medium dense, moist ,. . SP- SM 2.0 - MC= 2.40% Brown poorly graded SAND with gravel, medium dense, moist I-. -becomes dense, slight caving - __L SP -light iron oxide staining, becomes more coarse grained -- MC= 2.70% 6.0 -----Test pit terminated at 8.0 feet below existing grade. No groundwater encountered during excavation. Bottom of test pit at 8.0 feet. • Earth Solutions NW TEST PIT NUMBER TP-6 1805-136th Place N.E., Suile 201 Bellevue, Washington 98005 PAGE 1 OF 1 Telephone: 425-449-4704 Fax: 425-449-4711 CLIENT Ja:,: Marc Homes PROJECT NAME Ali;;'!ine Gardens PROJECT NUMBER 3377 ---PROJECT LOCATION Kin_g Count;t, Washington DATE STARTED 5/13/14 COMPLETED 5/13114 GROUND ELEVATION TEST PIT SIZE --~ EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS: EXCAVATION METHOD --· """" ---AT TIME OF EXCAVATION - LOGGED BY SHA CHECKED BY SHA AT END OF EXCAVATION ····-------- NOTES De~th ofTo~soil & Sod 6":_grass AFTER EXCAVATION - w :c: ~ ffi ui CJ Ii:., w a, <..i :i: Cl TESTS "-0 MATERIAL DESCRIPTION w---' :;; "' ~--' 0 "-::, :j :;; z Cl < en 0 TPSL d' "-5 TOPSOIL Brown poorly graded SAND with silt and gravel, dense, moist -- -I -coarse grained MC= 2_60% SP -heavy caving -- - ~ 5.p Test pit terminated at 5.0 feet below existing grade. No groundwater encountered during excavation. Bottom of test pit at 5.0 feet. • Earth Solutions NW TEST PIT NUMBER TP-7 1805 -136th Place N.E., Suite 201 PAGE 1 OF 1 Bellevue, Washington 98005 Telephone: 425-449-4704 Fax: 425-449-4711 CLIENT _,/ID, Marc Homes PROJECT NAME Al(:1'ine Gardens -- PROJECT NUMBER 3377 PROJECT LOCATION King Count~, Washington ····--·- DATE STARTED 5113114 COMPLETED 5113/14 GROUND ELEVATION TEST PIT SIZE EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS: EXCAVATION METHOD AT TIME OF EXCAVATION - LOGGED BY SHA CHECKED BY SHA AT END OF EXCAVATION - NOTES .J)J!.P.th ofTo~soil & Sod 6": grass AFTER EXCAVATION ··· w Cl. u r >-0:: <Ii 1-W r (!) t£ w"' TESTS <..i Cl. 0 MATERIAL DESCRIPTION w-...J:; "' ~...J Cl Cl. ::, ::i :.z (!) ;Ji o [fPSL ~ ' TOPSOIL 0.5 ;\ Brown poorly graded SAND with silt and gravel, medium dense to dense, moist " . SP " - -becomes more fine grained, decreasing silt 3.0 p-\ Brawn poorly graded GRAVEL with silt and sand, dense, moist 0 ['y • . GP l)o D' oO C ....L ,c-,, 5.0 \ I Brown poorly graded SAND with silt and gravel, dense, moist - MC=4.50% SP --I \ 8.0 -. Test pit terminated at 8.0 feet below existing grade. No groundwater encountered during excavation. Bottom of test pit at 8.0 feet. Appendix B Laboratory Test Results ES-3377 Earth Solutions NW, LLC • Earth Solutions NW GRAIN SIZE DISTRIBUTION 1805 -136th Place RE., Sutte 201 ' Bellevue, WA 98005 Telephone: 425-284-3300 CLIENT JavMarc Homes PROJECT NAME Al!;'.!ine Gardens Prelinina!}' Plat PROJECT NUMBER ES-3377 PROJECT LOCATION !S!!l!I Cou!l!J,< U.S. SIEVE OPENING IN INCHES I U.S. SIEVE NUMBERS I. HYOROMETER 6 4 3 2 1.5 1 1.4 1/23/8 3 4 6 810 1416 20 30 40 SO 60 100140200 100 I I ~ I I I I I I 95 -" 90 r\ 85 ' 80 \ 75 \ \ 70 \_ 65 f--r (!J 60 I ~ \ ~ 55 \ " a: " UJ 50 z la, u: f--45 z """ UJ I () 40 a: \ UJ "-35 \ 30 \ 25 \ 20 15 10 \ 5 -, 0 - 100 10 1 0.1 O.D1 0.001 GRAIN SIZE IN MILLIMETERS COBBLES I GRAVEL I SAND SILT OR CLAY I coarse fine I coarae medium fine Specimen Identification Classification LL PL Pl Cc Cu, 0 TP-1 3.0ft. uses: Brown Poor1y Graded SAND with Gravel, SP 0.86 5.28 18] TP-2 6.0ft. USDA: Tan Gravelly Loam. uses: SM. Specimen Identification D100 D60 D30 D10 %Gravel %Sand %Silt %Clay .o TP-1 3.0ft. 19 2.746 1.11 0.52 15.0 84.3 0.7 18] TP-2 6.0ft. 19 0.803 10.2 48.3 41.5 EMAIL ONLY Report Distribution ES-3377 JayMarc Homes 7525 Southeast 24th Street, Suite 487 Mercer Island, Washington 98040 Attention: Mr. Jay Mezistrano Earth Solutions NW, LLC THE ALPINE PLAT TRAFFIC IMPACT ANALYSIS CITY OF RENTON Prepared for Mr. Roy Boyer 14609 161"1 Ave. SE Renton, WA 98059 Prepared by C!i!lfEx TRAFFIC EXPERTS 11410 NE 124th St., #590 Kirkland, Washington 98034 Telephone: 425.522.4118 Fax: 425.522.4311 December 31, 2014 5 c.of•e.15 of' ~ ... -W,-c._ \2-qo,..+ RECEIVED JAN l 4 2015 CITY OF RENTON PLANNING D1VISION TraFf'&I:t December 31, 2014 Mr. Roy Boyer 14609 161 81 Ave. SE Renton, WA 98059 Re: The Alpine Plat -City of Renton Traffic Impact Analysis Dear Mr. Boyer: NORTHWEST TRAFFIC EXPERTS 11410 NE 124th St., #590 Kirkland. WA 98034 Phone: 425.522A 118 Fax: 425.522.4311 We are pleased to present this traffic impact analysis report for the proposed 28 lot Alpine plat localed on the south side of SE 144th St. between 1601h Ave. SE and 161 81 Ave. SE at 16023 SE 144th St. in the City of Renton. The scope of this analysis is based upon the preliminary plat site plan and the City of Renton Policy Guidelines for Traffic Impact Analysis for New Development. Our summary, conclusions and recommendations begin on page 5 of this report. PROJECT DESCRIPTION Figure 1 is a vicinity map showing the location of the site and study area. Figure 2 shows the preliminary site plan. The internal access streets connect to 1601h Ave SE and 161 81 Ave SE that border the east and west sides of the site. The internal site streets will have curb, gutter and sidewalk on both sides. Half street improvements including curb, gutter and sidewalk will also be installed on the site frontage on 1601h Ave SE, 161 51 Ave SE and SE 144th Street. Development of The Alpine Plat is expected to occur by the year 2017. Therefore, for purposes of this study, 2017 is used as the horizon year. The existing Alpine Nursery will be removed with this development. Page 1 The Alpine Plat TraH&'Jx TRIP GENERATION AND DISTRIBUTION The 28 single-family units in the proposed Alpine Plat are expected to generate the vehicular trips during an average weekday and during the street traffic peak hours as shown below: Time Period Trip Rate Trips Trips Total Trips per unit Entering Exiting 133 134 Average Weekday 9.52 267 50% 50% AM Peak Hour 0.75 5 16 21 25% 75% PM Peak Hour 1.00 18 10 28 63% 37% A vehicle trip is defined as a single or one direction vehicle movement with either the origin or destination (exiting or entering) inside the study site. The trip generation is calculated using the average trip rates in the Institute of Transportation Engineers (ITE) Trip Generation. Ninth Edition for Single Family Detached Housing (ITE Land Use Code 210). These trip generation values account for all site trips made by all vehicles for all purposes, including resident, visitor, and service and delivery vehicle trips. Figure 3 shows the estimated trip distribution and the calculated site-generated traffic volumes. The distribution is based on existing traffic volume patterns, the characteristics of the road network, the location of likely trip origins and destinations (employment, shopping, social and recreational opportunities), expected travel times, and previous traffic studies. EXISTING PHYSICAL CONDITIONS Street Facilities The streets in the study area are classified per the City of Renton Comprehensive Plan as follows: SE 144th St. 1601h Ave SE 161 81 Ave SE Page2 Collector Arterial Residential Access Residential Access The Alpine Plat Traff@;'! SE 144th St. has a speed limit of 25 mph and consists of two 11 ft. lanes and a paved shoulder approximately 6 to 8 feet wide in the vicinity of the project site. SE 144th St. is straight and flat at the intersections of 160th Ave SE and 161 st Ave SE with apparent good sight distance observed in both directions. Both intersections are controlled with stop signs on the minor approaches. There are no curbs, gutters or sidewalks on SE 144th St., 160th Ave SE and 161st Ave. SE in the project vicinity. EXISTING TRAFFIC CONDITIONS Traffic Volumes Figure 4 shows existing, future without project and future with project PM peak hour traffic volumes atthe 160th Ave SE/SE 144th St. and 161 st Ave SE/SE 144th St. intersections. PM peak hour traffic volume turning movement counts were conducted on December 16, 2014 at the study intersections and are included in the technical appendix. Per the City of Renton Policy Guidelines for Traffic Impact Analysis for New Development intersections and road segments that experience an increase of 5% in traffic volumes require analysis. The two study intersections meet these requirements. Level of Service Analysis Level of Service (LOS) is a qualitative measure describing operational conditions within a traffic flow, and the perception of these conditions by drivers or passengers. These conditions include factors such as speed, delay, travel time, freedom to maneuver, traffic interruptions, comfort, convenience, and safety. Levels of service are given letter designations, from A to F, with LOS A representing the best operating conditions (free flow, little delay) and LOS F the worst (congestion, long delays). Generally, LOS A and B are high, LOS C and D are moderate and LOS E and F are low. Table 1 shows calculated level of service (LOS) for existing and future conditions including project traffic at the pertinent street intersection. The LOS was calculated using the procedures in the Transportation Research Board Highway Capacity Manual The LOS shown indicates overall intersection operation. At intersections, LOS is determined by the calculated average control delay per vehicle. The LOS and corresponding average control delay in seconds are as follows: Page 3 The Alpine Plat TraHINJr! TYPE OF A B C D E INTERSECTION < >10.0 and >20.0 and >35.0 and >55.0 and - Signalized 10. ~20.0 ~35.0 ~55.0 ~80.0 0 Stop Sign Control ~10 >10and<15 >15 and ~25 >25 and ~35 >35 and ~50 .0 FUTURE TRAFFIC CONDITIONS WITHOUT THE PROJECT Figure 4 shows projected 2017 PM peak hour traffic volumes without the project. These volumes include the existing traffic volume counts plus background traffic growth. The background growth factor accounts for traffic volumes generated from other approved but unbuilt subdivisions (pipeline projects) and general growth in traffic traveling through the area. A 3% per year annual rate was added for each year of the two year time period (for a total of 6%) from the 2015 traffic count to the 2017 horizon year of the proposal. From other recent nearby studies, the 6% increase is sufficient to cover trips generated by pipeline projects plus the general background growth in traffic. FUTURE TRAFFIC CONDITIONS WITH PROJECT Figure 4 shows the projected future 2017 PM peak hour traffic volumes with the proposed project. The site-generated PM peak hour traffic volumes were added to the projected future without project volumes to obtain the future with project volumes. Table 1 shows calculated LOS for future with project volumes at the study intersections. The study intersections operate at an acceptable LOS B for future 2017 conditions. TRAFFIC MIT/GA TION REQUIREMENTS The City of Renton requires a Transportation Mitigation Fee payment of $75 per new daily trip attributed to new development. The 28 single family units in the Alpine plat will generate 267 new trips per day resulting in an impact fee of $20,025 (267 daily trips X $75 per unit). Typically, credit is given for reduction in trips due to the removal of existing facilities. Using the ITE Trip Generation rate of 108.1 daily trips per acre for a Nursery (land use code 817), the 5.62 acre Alpine Nursery generates 608 trips per day. The removal of the Alpine Nursery along with the development of the Alpine plat should Page4 F >80. 0 >50 The Alpine Plat TraHjg;g therefore result in a net decrease of 341 trips per day (608 trips minus 267 trips per day). Therefore, no transportation mitigation fee should be required. SUMMARY, CONCLUSIONS AND RECOMMENDATIONS We recommend that the Alpine Plat be constructed as shown on the site plan with the following traffic impact mitigation measures: • Construct the street improvements including curb, gutter and sidewalk for the internal site streets and half street improvements along the site frontage on 1601h Ave SE, 161 51 Ave SE and SE 144th Street. No other traffic mitigation should be necessary. If you have any questions, please call 425-522-4118. You may also contact us via e-mail at vince@nwtraffex.com or larry@nwtraffex.com. Very truly yours, Vincent J. Geglia Principal TraffEx Page 5 Larry D. Hobbs, P.E. Principal TraffEx TABLE 1 PM PEAK HOUR LEVEL OF SERVICE SUMMARY THE ALPINE PLAT TRAFFIC IMPACT ANALYSIS EXISTING 2015 WITHOUT 2015 WITH INTERSECT/ON 2013 PROJECT PROJECT 16CYh Ave SE/ SE 144th St B 12.1 SB B 12.1 SB B 12.4 SB 161 51 Ave SE/ SE 144th St B 10.6 NB B 10.8 NB B 11.0 NB * Number shown is the average control delay in seconds per vehicle for the worst approach or movement which determines the LOS for an unsignalized intersection per the Transportation Research Board Highway Capacity Manual (XX) LOS and average control delay NB northbound approach SB southbound approach Page6 ·1 ';sE.l341hSt·; ~, ' Ii <;<:(:§~ ,13,6th St 1 SE 5th St SC 5th Pl SE 7rh St SE Rth $1 SE 1~3rd St "' m .SE' I 44th St SE 1·t>J/'1 ~. The Alpine Plat· City of Renton Vicinity Map SE 138th St j l:!:i!l!Ex TRAFFIC EXPERTS ,. ' · -·sf l34lh:St Sc.J40th S! SE 135/hj SE 136th ! ! ~ Sll42ndSr 1; , i's Figure 1 _.__ ---... ----· ------~-----,-------c:-r,, _l_ " /' '" / ' ,, ' ' \ ,--\ . • I . / I _j__ , :---1 --7 I , i ~ f . / ,---1 i ,,_ I ' I ' I I 1 ~--1---~ , I , , ,.,; ~ I ! I ) "'--_____ j ___ --- 1 __ ---- I ' , I ' ' I " ' /----- ' ' I I ' ' \ " ------- " ( ----··---- ' \ ' ' " \ ------------;- The Alpine Plat • City of Renton Site Plan " " \ Figure 2 ,SL b1!1 Pl -4 8- SF, /111 '~-l PM Peak Hour Traffic Volume Enter 18 Exit 10 Total 28 Proj~t Sites 1• < " "' .~ 160th Ave/ SE 144th 135% I -6 .. ,l"tl ,,. 4-~-'1 .. 1 .. ,. M 14/tl: '.51 161stAve SE 144th The Alpine Plat -City of Renton PM Peak Hour Trip Generation and Distribution '!!i![fEx TRAFFIC EXPERTS .. :j ~ ;;;l 11.;~,1u s~ J> ' C " " sr ltA1h st Legend 15% Percentage of Project Traffic -3 PM Peak Hour Traffic Volume Figure 3 Hb1t1PI , .. ' •" Existing '° <O -M v ,. ,., 12_,-' I CL 31 118-CI) -137 f' ... t rr 1 M "' 0 160th Ave/ SE 144th v a a 3-'J I I..'-1 133-®-104 58 .. \ I Cr 4 " a "' "' 161st Ave SE 144th SF 5th St Projei.t Site ,. < " "' .~ Future without Project "' "' -M s,- 13 _,-' I CL 33 125-CI) -145 -. r 3 0 t C 1 MN 0 160th Ave/ SE 144th s,-a a 3-'J I i..'-1 141-®-110 62',,cr4 "' a "' N 161st Ave SE 144th ~jf: 14~th s: 1,• ~, The Alpine Plat· City of Renton PM Peak Hour Traffic Volumes Project Traffic 0 N N Q_, .I I s L 1 4-CI)-2 ' r 4 > t C 3 160th Ave/ SE 144th 161stAve SE 144th 1:!i!!fEx TRAFFIC £XP£RT5 Sf l 4(ltl1 :::S!' .. .. , ~~ ~E:. l l;'.f,u' S:' ,. ' " ,. " Future with Project 160th Ave/ SE 144th v a a 3.Jl.1J1.._1 143-®-113 68-.,,cr7 re C) co 161stAve SE 144th Figure 4 TECHNICAL APPENDIX 2 Prepared for Traffex Traffic Count ConSJltants, Inc. Rion!!:(~ 933-00J9 FAX: (25J)922-7211 EMzil: Taim@rC.!inc:.o:m WBE/DllF. lntlllraectlon: 160th A,·e SE & ~E 144th SL DeleofCount: Tues 12116/2014 Jess Localon: Renton, Washinton Checked By; Time From North on (SB) From South on (NB) From East on M9l From ""'9st on (EB) Interval Interval 160th Ave SE 160th Ave SE SE 144th St SF. 144th St Total Endin<> ntl-'r'"'""'L""F'";,;:ar-R,-+-,T,-,--:L"'ii"'O,,'-"'-r--:R,-+-r,,.."T"--i,_"'-C:,:::!.:,,,--,---:R:-+s.Jc' "T~Lc.;:;:::;,;,"-,--,R,-11---'"""---I 4:15 P 4:30 P 4:45 P 5:00 P 5:l5P 5:30 P 5:45 P 6:00 P 6:15P 6:30 P 6:45 P 7:00 P Total Surveu Total %HV PHF 392700 0 02 0 26 6 0 9 2 II JO 0 0 16 0 4 13 10 0 11 0 0 0 0 0 0 0 0 0 0 0 0 0 0 37 2 I 46 I 3 I 1s 67 OB< SE 144th St 011 05 l 587 0 l 1 0 0 0 31 4 0 l O O I O 18 4 000 01 0 306 0 0 0 0 2 0 34 4 0 0 0 0 I O 19 S 0 U O O 2 0 28 5 00 0 0 0 0 0 0 00 0 0 0 0 0 0 00000 0 00 00 0 0 0 0 0 0 14 244 Peak Hour: 4:15 PM " 5:15PM 0 2 I o 137 159 "" .... 08' 0,,) 160th Ave SE I 102 I 1, I 46 35 I r-----, , 0 ,Bike ,------. L ..... 0 ....... i Ped 41 21 I lS8 I Pedj'_'X_:j Bike 4 33 0 87 6 26 0 115 2 24 2 " 0 65 40 99 0 25 0 86 0 41 0 80 0 36 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 23 2SJ 3 704 u I 12 118 364 133 364 "'" .... 0.77 0.79 SE 144th St I 3211 • 0 •Bike L!!!_I 4:15PM 5:15 PM 1----1 r::-:-, L. .... o ..... !Ped ~ INT 01 INT 02 INT 03 INT 04 INT 05 INT 06 INT 07 N s E w ' l I INT 08 __ _ INT 09 , _ •• INT 10 • INT 11 INT 12.1---~·-.,., ---,,_-~ -- '" " S=cial Notes The driveway on the south side, parallel to 3 l 0 0 I 0 0 0 0 0 0 0 5 Pedr.·.-.-~----_-_! ' I I • ' ' Hike: __ !/ __ _: I n I 160th Ave SE Blcyclee From:, l-"N4 1_,s,_,_1_.E _ _,_ l~W'--j INT01 i ] 2 3 INT 02 I I I INT03 I 0 INT04 I 0 INT 05 0 INT061·•· 0 :~~:::.. --··1 ~ the south leg of 160th A,•e SF. had very minimal traffic. No vehicles turned into the driveY..-ay during the count period, and (1) vehicle made a left INT 09 0 JNT 10 0 -- INT 11 0 ~T12.l----,---,'~-------..----,0 out of the driveway during the 4th interval ol 1 o 3 4 ~ 1.0 PHF Peak Hvur Vofr,me PHF %HY Che;;k F.B 0.77 wn 0.60 4.S% 4.4% In: 364 NB,i-,00,603+---""ls'--I ou1: 364 se . ..,o0.s0•+-s'c·'o"s•--1 ~---" T lnl,,e,;:0".7~9.__4"."IS~,--1 !conditions; I TRA 14140M 01 ' I I Traffex Prepared for: Traffic Count ConSJ!tants, Inc. A,~:(2SJJ 92EH:009 FAX :(253) 9:zl-?211 E-M;:il: T C1rn@JT'C2irl::.com WBE/DBE ln19rseclion: l6lstAveSE&SE l44thSt Dale of Count: Tues 12/16/2014 Location; Renton, Washinton Cl-ecked By: ks, Time From North on (SB} From South on tNB) From East on (WB) From Wnt on (EB) Interval Interval 161st Ave SE 161st Ave SF. SE 144th St SE 144th St Total Endine at T L s R T L s R T L s R T L s R 4:15 P 0 0 0 0 0 4 0 l 4 3 28 0 2 l 29 12 78 4:30 P 0 0 0 0 l 8 0 0 2 l " 0 2 0 30 5 102 4:45 P 0 0 0 l 0 2 0 l 0 l 32 0 l 0 26 ll 74 5:00 P 0 0 0 I 0 4 0 0 I 0 18 I 3 0 28 9 61 5:l5P 0 0 0 l 0 3 0 0 l 0 33 I I 0 34 22 94 5:30 P 0 0 0 I 0 2 0 2 2 2 34 0 0 0 31 8 so 5:45P 0 0 0 2 0 7 0 4 I I 16 0 0 l 34 15 80 6:oo r 0 0 0 0 l 12 0 0 I l 21 0 0 2 34 13 R1 6:15 P 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 6:30 P 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 6:45 P 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 7:00P 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Total Survey 0 0 0 6 2 42 0 s 12 9 240 2 9 4 246 95 652 Peak Hour: 5:00PM 10 6:00PM Total 0 o I 0 I 4 I Annro~ch 4 %HY .. PHF O.>J ; SE 144th St I m I Ped:_ .~ ..... ! Bike 0 I ml ' ~I 1-- ~ 58 rnis Acms,: N s E w 1NT01 . --J. l INT02 1----I_ ---· I INT03 0 .. - INT04 0 1----··· .•. INT05 0 - INT 06 I 0 I·· INT07 1------0 INTOB 1---.. . .. 0 INT 09 0 INT 10 1----.. . 0 INT 11 1----; ----0 1NT12 I-... 0 "' "' 2 Snecial Notes 24 0 I 6 5 30 ""' 0"'3 161stAveSE I 8 ~ ' , I , 4 I 104 109 .... o .... I 4 I r-----1 , (J ,Hike r.·.--~·-1Ped l ,----!_ 104 ~ 4 l 3 luJlss 337 194 337 -., .. ,., 0.90 SE 144th St I 2481 0 Bike 5:00 PM lo 6:00 PM 1---- L._·-~-· Ped ~ Pedl ...... .Y ...... ..J 24 Bikci __ g._J I " I 161st Ave SE Blcydee From: 1-~"~l~•~+-•~--,-~w~ I I INT01 INT02 INT03 INT04 INT05 INT 06 INT07 INTOB INT09 INT 10 ---·-0 ' -------i--0 'i_ ____ J,. " 0 .. !.. . i. --· --· -0 I I . .. o ----N'O BlKES . -----0 --T ---T 0 ---____ ll ___ ----:_--i I o INT 11 ! 0 INT 12~·-·....,,,---i-----i----lO ol ol o oo ~ 1.0 PHF Peak Hour Volume PHF %HY SB 0.87 0.5% Check WB 0.76 4.6% In: 3J7 NB 0.63 3.3% Out: 3J7 SB 0.50 Tint. 0.90 2.1% I conditions: I TAA 14140M 02r Existing PM Peak Hour 3: 160th Ave SE & SE 144th St Int Delay, s/veh 2.1 Vol, veh/h 12 118 3 1 137 31 3 2 0 46 Conflicting Peds, #/hr 0 0 0 0 0 0 0 0 0 0 Sign Control Free Free Free Free Free Free Stop Stop Stop Stop RT Channelized None None None Storage Length Veh in Median Storage, # 0 0 0 Grade,% 0 0 0 Peak Hour Faclor 79 79 79 79 79 79 79 79 79 79 Heavy Vehicles, % 4 4 0 0 5 5 0 0 0 3 Mvmt Flow 15 149 4 1 173 39 4 3 0 58 !illfoll!l!1norilf'~r~lita'!WilJor:1~:!'Wi~!Hl!!i:lll})al'.d'm~-~-Jtlil'fMN Conflicting Flow All 213 O O 153 O O 379 397 151 379 Stage 1 182 182 196 Stage2 197 215 183 Critical Hdwy 4.14 4.1 7.1 6.5 6.2 7.13 Critical Hdwy Stg 1 6.1 5.5 6.13 Critical Hdwy Stg 2 6.1 5.5 6.13 Follow-up Hdwy 2.236 2.2 3.5 4 3.3 3.527 Pot Cap-1 Maneuver 1345 1440 582 544 901 577 Stage 1 824 753 803 Stage 2 809 729 816 Platoon blocked, % Mov Cap-1 Maneuver Mov Cap-2 Maneuver Stage 1 Stage 2 1345 1440 573 537 901 573 537 814 744 804 728 569 569 793 803 HCMControlDelay,s 0.7 0 11.5 12.1 HCM LOS B B HCM Control Delay (s) HCM Lane LOS HCM 95th %tile Q(veh) 0 A 0 A 12/31/2014 3 0 Stop 0 0 79 0 4 380 196 184 0 0 Stop None 79 3 0 6.5 6.23 5.5 5.5 4 3.327 556 846 742 751 549 846 549 741 742 Baseline Synchro 8 Light Report Page 1 Existing PM Peak Hour 6: 161st Ave SE & SE 144th St 12/31/2014 Int Delay, s/Veh 1.2 Vol, veh/h 3 133 58 4 104 1 24 0 6 0 0 4 Conflicting Peds, #/hr 0 0 0 0 0 0 0 0 0 0 0 0 Sign Control Free Free Free Free Free Free Stop Stop Stop Stop Stop Stop RT Channelized None None None None Storage Length Veh in Median Storage,# 0 0 0 0 Grade,% 0 0 0 0 Peak Hour Factor 90 90 90 90 90 90 90 90 90 90 90 90 Heavy Vehicles, % 0 4 0 0 5 0 0 0 0 0 0 0 Mvmt Flow 3 148 64 4 116 1 27 0 7 0 0 4 M~l<lr!M!nor~?:·:~~,~:;~~Ml!iaa~~~wria!'A.i!$iii,m~i\f;~~M'f.J".f:~tt~1:i~~- Conflicting Flow All 117 0 0 212 0 0 314 313 180 315 344 116 Stage 1 187 187 125 125 Stage 2 127 126 190 219 Critical Hdwy 4.1 4.1 7. 1 6.5 6.2 7.1 6.5 6.2 Critical Hdwy Stg 1 6.1 5.5 6.1 5.5 Critical Hdwy Stg 2 6.1 5.5 6.1 5.5 Follow-up Hdwy 2.2 2.2 3.5 4 3.3 3.5 4 3.3 Pot Cap-1 Maneuver 1484 1370 643 606 868 642 582 942 Stage 1 819 749 884 796 Stage 2 882 796 816 726 Platoon blocked, % Mov Cap-1 Maneuver 1484 1370 638 603 868 635 579 942 Mov Cap-2 Maneuver 638 603 635 579 Stage 1 817 748 882 794 Stage 2 875 794 808 725 M~roai:tii:;g:,:~~»~""~.!il!!il$~a~~~~w~I1:£J;l'::'ioNs~:"~•~_,,1~-• HCM Control Delay, s 0. 1 HCM LOS 0.2 Baseline 7.4 A 0 0 A 0.3 0 A 0 10.6 B 8.8 A Synchro 8 Light Report Page2 Future Without Project PM Peak Hour 3: 160th Ave SE & SE 144th St Int Delay, s/veh 2.6 Vol, veh/h 12 125 3 Conflicting Peds, #/hr 0 0 0 Sign Control Free Free Free RT Channelized None Storage Length Veh in Median Storage, # 0 Grade,% 0 Peak Hour Factor 79 79 79 Heavy Vehicles, % 4 4 0 Mvmt Flow 15 158 4 1 0 Free 79 0 1 t;!ajo11ti:i1nor,~t~•lfdtl~~~- Conflicting Flow All 225 0 0 162 Stage 1 Stage 2 Critical Hdwy 4.14 4.1 Critical Hdwy Stg 1 Critical Hdwy Stg 2 Follow-up Hdwy 2.236 2.2 Pot Cap-1 Maneuver 1332 1429 Stage 1 Stage 2 Platoon blocked, % Mov Cap-1 Maneuver 1332 1429 Mov Cap-2 Maneuver Stage 1 Stage 2 12/31/2014 145 33 3 2 0 49 5 19 0 0 0 0 0 0 0 0 Free Free Stop Stop Stop Stop Stop Stop None None None 0 0 0 0 0 0 79 79 79 79 79 79 79 79 5 5 0 0 0 3 0 3 184 42 4 3 0 62 6 24 6.2 6.23 3.3 890 527 521 890 552 535 834 527 521 552 535 805 737 783 733 755 718 795 736 f,jfd&'l'iioi/Ma!o~1ffliN!!lfflDR»-!lf'JEJ:l1MWIIii\lW,Br;~wli8:SBLll1l .. ':!k1lf;~j;"~~kJ!:)~~.~-- Capacity (veh/h) 525 1332 1429 604 HCM Lane V/C Ratio 0.012 0.011 0.001 0.153 HCM Control Delay (s) 11.9 7.7 0 7.5 0 12 HCM Lane LOS B A A A A B HCM 95th %tile O(veh) o o O 0.5 Baseline Synch ro 8 Light Report Page 1 Future Without Project PM Peak Hour 6: 161st Ave SE & SE 144th St Int Delay, s/veh 1.2 Vol, veh/h 3 141 62 Conflicting Peds, #/hr 0 0 0 Sign Control Free Free Free RT Channelized None Storage Length Veh in Median Storage, # 0 Grade,% 0 Peak Hour Factor 90 90 90 Heavy Vehicles, % 0 4 0 Mvmt Flow 3 157 69 rdM~™-· Conflicting Flow All Stage 1 Stage 2 Critical Hdwy Critical Hdwy Sig 1 Critical Hdwy Sig 2 Follow-up Hdwy Pot Cap-1 Maneuver Stage 1 Stage 2 Platoon blocked,% Mov Cap-1 Maneuver Mov Cap-2 Maneuver Stage 1 Stage 2 123 4.1 2.2 1477 1477 0 4 0 Free 90 0 4 4.1 2.2 1354 1354 110 0 Free 0 0 90 5 122 0 12/31/2014 1 25 0 6 0 0 4 0 0 0 0 0 0 0 Free Stop Stop Stop Stop Stop Stop None None None 0 0 0 0 90 90 90 90 90 90 90 0 0 0 0 0 0 0 1 28 0 7 0 0 4 0 6.2 7.1 6.2 6.1 6.1 3.3 3.5 3.3 856 624 933 876 874 805 620 589 856 617 564 933 620 589 617 564 806 740 874 789 867 789 797 715 rn-li'i8:irr--·r·-·=,.,··""····'.''<'1'',Sli<!FIK"""fi"'TMk~....JLlkP&:1£1£..-!iir,R.._llllllmlli_. w~aiuritil\/.i:funpv!3Ln:1.fli,'J;Bliii11ll~81!ll,'4!,;0¥w¥'!""l"i'1J! ~~ Capacity (veh/h) 655 1477 1354 933 HCM Lane VIC Ratio 0.053 0.002 0.003 -0.005 HCM Control Delay (s) 10.8 7.4 O 7.7 0 8.9 HCM Lane LOS B A A A A A HCM 95th %tile Q(veh) 0.2 0 0 0 Baseline Synchro 8 Light Report Page 2 Future With Project PM Peak Hour 3: 160th Ave SE & SE 144th St Int Delay, s/veh 2.8 Vol, veh/h Conflicting Peds, #/hr Sign Control RT Channelized Storage Length Veh in Median Storage, # Grade,% Peak Hour Factor Heavy Vehicles, % Mvmt Flow HCM Control Delay, s HCM LOS 13 0 Free 79 4 16 4.14 2.236 1327 1327 0.7 129 7 0 0 Free Free None 0 0 79 79 4 0 163 9 4 0 Free 79 0 5 4.1 2.2 1417 1417 0.2 147 34 0 0 Free Free None 0 0 79 79 5 5 186 43 5 3 0 0 Stop Stop 0 0 79 79 0 0 6 4 509 505 509 505 795 729 743 708 2 0 Stop None 79 0 3 6.2 3.3 881 881 ~~·''~'"' . i~t ... ilh", 11.6 B 12/31/2014 51 5 19 0 0 0 Stop Stop Stop None 0 0 79 79 79 3 0 3 65 6 24 6.23 528 517 830 528 517 772 723 779 726 12.4 B KWB~a~ritffi'l!q:BEnWl'.~EB'iJP.,iiEBJ!:i~[SRliWlll'i:WBE~WB~ifLli',}fflM U MW1B!!iii~~i!;ili!:ffl Capacity (veh/h) 555 1327 1417 581 HCM Lane V/C Ratio 0.023 0.012 0.004 0.163 HCM Control Delay (s) 11.6 7. 7 0 7.5 O 12.4 HCM Lane LOS B A A A A B HCM 95th %tile Q(veh) 0.1 0 O 0.6 Baseline Synchro 8 Light Report Page 1 Future With Project PM Peak Hour 6: 161st Ave SE & SE 144th St Int Delay, s/veh 1.3 Vol, veh/h 3 143 68 Conflicting Peds, #/hr 0 0 0 Sign Control Free Free Free RT Channelized None Storage Length Veh in Median Storage,# 0 Grade,% 0 Peak Hour Factor 90 90 90 Heavy Vehicles, % 0 4 0 Mvmt Flow 3 159 76 filajq'l'JMlftdr~li;~Ql 7 113 0 0 Free Free 0 0 90 90 0 5 8 126 12/31/2014 1 28 0 8 0 0 4 0 0 0 0 0 0 0 Free Stop Stop Stop Stop Stop Stop None None None 0 0 0 0 90 90 90 90 90 90 90 0 0 0 0 0 0 0 1 31 0 9 0 0 4 Conflicting Flow All 127 0 O 234 0 0 347 345 197 350 383 126 Stage 1 203 203 142 142 Stage 2 144 142 208 241 Critical Hdwy 4.1 4.1 7.1 6.5 6.2 7.1 6.5 6.2 Critical Hdwy Stg 1 6.1 5.5 6.1 5.5 Critical Hdwy Stg 2 6.1 5.5 6.1 5.5 Follow-up Hdwy 2.2 2.2 3! 4 3J 3! 4 ll Pot Cap-1 Maneuver 1472 1345 611 581 849 608 553 930 Stage 1 Stage 2 Platoon blocked, % MovCap-1 Maneuver 1472 Mov Cap-2 Maneuver Stage 1 Stage 2 HCM Control Delay, s 0.1 HCMLOS 804 737 866 783 864 783 799 710 1345 604 576 849 598 549 930 604 576 598 549 802 736 864 778 855 778 789 709 ;;rm~rJl~~e&af6~--ffaw1.Kt1:,a1.:;~1,sr1!f!aaa•~fHat'8WBBWElrn1l:';~~~•ll Capacity (veh/h) 645 1472 1345 930 HCM Lane V/C Ratio 0.062 0.002 0.006 0.005 HCM Control Delay (s) 11 7.5 0 7.7 0 8.9 HCM Lane LOS B A A A A A HCM 95th %tile Q(veh) 0.2 0 0 0 Baseline Synchro 8 Light Report Page 2