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Storm Drainage Report for Brandon Lee Short Plat 2709 Talbot Road South, Renton WA MAC ! 3 2009 Prepared far: RECEIVED Brandon Lee 618 Pasco Place NE Renton, Washington Prepared by: Nhan Vo 1922 Arab Drive SE Olympia, WA 98501 (360) 951-6678 September, 2008 ENGINEER CERTIFICATION "1 hereby state that this Drainage and Erosion/Sediment Control Plan for the Brandon Lee Short Plat project has been prepared by me or under my supervision and meets the standard of care and expertise which is usual and customary in this community for professional engineers. I understand that City of Renton does not and will not assume liability for the sufficiency, suitability, or performance of drainage facilities prepared by me." © 1RES:72116! Nhan D. Vo, P.E. TABLE OF CONTENTS SECTION 1 DRAINAGE PLAN..............................................................................................1-1 1. Introduction ........................ 1-1 ProjectOverview ................. ................................................... I ................................... ...1-1 II. Preliminary Conditions Summary.................................................................................... 1-2 III. Off -site Analysis.............................................................................................................. 1-2 IV. Retenton/Detention Analysis and Design........................................................................ 1-2 V. Conveyance System Analysis and Design ...................................................... ................. 1-3 VI. Special Reports and Studies.............................................................................................1-3 VII. Basin And Community Plan Areas..................................................................................1-3 VIII. Other Permits................................................................................................................... 1-3 IX, Temporary Erosion And Sediment Control Analysis and Design ................................... 1-3 a) Construction Sequence and Procedure.............................................................................1-3 b) Trapping Sediment ............... ....................... ..................................................................... 1-4 c) Control of pollutants other than sediment .................... - d) ............................................. utilities .................................................................... 1-4 e) Organization Responsible for Maintenance .................... - f) Catch Basins.................................................................................................................... 1-5 g) Vegetation Management Plan.......................................................................................... 1-5 ATTACHMENT: EXHIBIT A: Existing Site Conditions EXHIBIT B: Proposed Site Conditions EXHIBIT C: Temporary Erosion Control EXHIBIT D: Erosion Control Details APPENDIX A: Geotechnical Study Wetland Studies and Delineation APPENDIX B: General Soils Map Hydrologic Soil Group SCS Western Washington Runoff Curve Numbers APPENDIX C: Roof Drainage Calculations Brandon Lee Short Plat Storm Drainage Report i Ady 2008 n \ � ] 302305 OYd <`i 'Ill s G0l ��I '! ,rl �� �•}� y 4, 1i ♦ i�.. I '�. nk - M yr� � � ��� - �I_ Y" I FgA ter; • • .n , rl I x = t � � = �, 1� ` � r g � t F1rr1 s1ll r ca Mllr �_ � 1 '�R 3,j°n 9'`t 1R! •y�Y ;+� 9JRI 't r�l t�'t t� v - �� iWY�4nf bs I g It a iif111R — _ r�'r tll II S♦ it f '� � � � P<p ur " � � m0 � T'A ,i _--i-_ i VICTOR K VICINITY MAP NOT TO SCALE SECTION 1 DRAINAGE PLAN I. INTRODUCTION This is the Stormwater Site Plan (SSP) for the proposed short plat for 2709 Talbot Road South located within the limits of Renton, Washington. It contains the technical information and analysis necessary for regulatory agencies to evaluate stormwater drainage and erosion controls for the improvements at the proposed site. This SSP has been prepared in accordance with the City of Renton ,Surface Water Management Requirements and will document the existing and proposed site conditions and detail the design of water quantity and conveyance system structures for the purpose of controlling storm runoff from the site. PROJECT OVERVIEW This report is in response to the City of Renton's (City) request for proposed short plat development of an existing parcel into two single-family lots. The parcel is located at 2709 Talbot Road South in Renton, WA (Tax Parcel No. 3023059036). The current zoning and landuse planning criteria for the above tax parcels is R-8. Single family homes are an allowed use in this zoning classification. The general vicinity of the project area is shown on Exhibit 1-1. The project site consists of approximately 51,253 square feet (1.18 acres), located within the Northeast quarter of Section 30, Township 23N, Range 05E, W.M., Renton, WA. The proposed project will divide the existing parcel into two lots with each lot area as shown in the following table: Surface Categories LOT 1 (Sq. Ft.) (Acre) LOT 2 (Sq. Ft.) (Acre) Total Area (Acres) Buildable Area 8,918 0.205 6,243 0.142 0.347 Steep Slope Area 9,683 0.222 10,649 0.244 0.467 Steep Slope Buffer 2,205 0.051 1,633 0.037 0.088 Wetland Area 4,358 0.100 7,564 0.174 0.275 Total 255164 0.578 26,089 0.599 1.177 Although the overall parcel is larger than 1 acre but only 0.35 acre of the said lot is buildable. With the existing house is situated on Lot 1 with a total area of approximately 25,168 square feet (8,910 buildable square feet) and Lot 2 with a total area of approximately 26,085 square feet (6,205 buildable square feet). Lot 2 is proposed for the new development; thus, grading, drainage, and utilities improvements are required. Based on the topographic constrains and available of existing utilities, the square footage of the proposed building for Lot 2 will limit to 3,500 square feet in area with associated driveway entrance and landscaping. Brandon Lee Short Plat Storm Drainage Report 1-1 July 2008 The developed site will drain by overland flow to a well -grown grass and shrugs area in the west side behind the proposed building and follow the existing drainage pattern to the existing wetland crossing the westerly portion of the site. Roof runoff from the proposed building will be collected by downspouts and disposed into an underground infiltration system per City of Renton requirements. No storm runoff from the site will enter the public or adjacent properties. No off - site drainage areas contribute to the site; thus, off -site stormwater analysis is not applicable to this site. A Technical Information Report (TIR) Worksheet is used as a guideline in the Manual. This project has followed the design steps outlined in the TIR to prepare this SSP and report. The TIR Worksheet is included in Appendix A. The objective of this report is to determine the required size of the stormwater system for the Brandon Lee Short Plat project located at the 2709 Talbot Road, Renton, Washington. II. PRELIMINARY CONDITIONS SUMMARY The project will consist of constructing infrastructure to service the residential dwellings as required per City of Renton design standards. The infrastructure will include the following: installation of new driveway for the new lot, utilities (water, sewer, gas, etc.) to serve the site, and stormwater management. It is the intention to utilize the Best Management Practices (BMP's) as established by the 1992 King County Surface Water Design Manual (Manual) to minimize sediment runoff and erosion, while meeting water quality requirements prior to discharging from the project site. An Exhibit to show the proposed site development and drainage basin for this project is included in this section for your review. Geotechnical, wetland studies and soils analysis were performed on the site to delineate the setback lines for wetland buffer and steep slopes to ensure that the proposed building will be placed away from these sensitive areas. The geotechnical and wetland reports are included in Appendix A for your review. II1. OFF -SITE ANALYSIS Storm runoff from the roof will be collected and infiltrate into the ground through the infiltration trench behind the building. The infiltration trench will be design according to the City of Renton standards/requirements. Surface runoff from the site will flow in the same patterns as it was before the site was developed. Runoff from the yard is very minimal and will sheet flow through the planter strip (grass area in the back yard) before it flows to the lower land and finally discharges into the wetland buffer and wetland in the northern portion of the site. No erosion and flooding are anticipated and no down stream or off -site will be impacted as part of the development of this project. IV. RETENTON/DETENTION ANALYSIS AND DESIGN Per 1992 King County Surface Water Desgin Manual — Core Requirements 43, this project is exempt from on -site peak runoff control because of the following reasons: Brandon Lee Short Plai Storm ,Drainage Report 1-2 Ady 2008 (1) The proposed project site post -developed peak runoff rate for the 100-year, 24-hour duration design storm event for each discharge location to be less than 0.5 efs more than the peak runoff for the existing site conditions; OR, (2) The project proposes to construct 5,000 square feet, or less, of new impervious surface. For the project, the proposed impervious surface for the site is less than 5,000 square feet; so peak runoff control from the site is exempt. V. CONVEYANCE SYSTEM ANALYSIS AND DESIGN No conveyance system is proposed for the project except the roof downspout and the roof infiltration trench is used in accordance with the City of Renton Standards. VI. SPECIAL REPORTS AND STUDIES Geotechnical studies and reports were performed on the project site and is included in this report for your review. Wetland delineation and report was also performed on the site to locate the wetland on -site and is included in this report for your review. VII. BASIN AND COMMUNITY PLAN AREAS This project is not part of the Basin and Community Plan Areas. VIII. OTHER PERMITS Only Storm Drainage and Site Development permits are applied for this project. The property owner or his/her designated person will apply for other permits if required by the City of Renton. IX. TEMPORARY EROSION AND SEDIMENT CONTROL ANALYSIS AND DESIGN a) Construction Sequence and Procedure The intent of delineating a construction sequence and procedure is to protect the existing and new storm drainage systems from erosion and sedimentation deposits. Protecting the existing drainage systems, such as catch basin, ditches, etc. from sedimentation requires controlling sediment laden runoff and backfilling open trenches each day and installing inlet protection in the catch basins. The contractor will be reminded of the importance of closing open trenches each day. Grass vegetation (sod or seed) will be accomplished as soon as possible following construction of the site. The contractor shall install erosion control facilities shown on the plans prior to any land disturbing activities. Silt fence shall be installed as the first activities. The remaining silt fence surrounding the proposed building foundation, gravel infiltration trench, and grading limits may be installed prior to excavation of these facilities. Brandon Lee Short Plat Storm Drainage Report 1-3 .hily 2008 b) Trapping Sediment Construction entrance is proposed for the site. Any accumulation of mud and debris on the tires of construction vehicles should be knocked off prior to entering the public street. Periodic sweeping of the road would ensure no tracking to the Talbot Road occurs. Daily inspections of the public right-of-way for accumulation of mud or debris shall occur. If mud or debris is found, street sweeping will be required. Siltation fences will be placed at the downstream side of the cut and/or filled slopes, which will minimize the amount of sediments leaving the project site. The sediment control facility such as silt fence, construction entrance, and catch basin inlet protection shall be inspected after every storm event to ensure accumulation of sediment remains a minimum and/or replace or remove by if necessary. c) Control of pollutants other than sediment It is the contractors' responsibility to prevent, reduce, or eliminate the discharge of pollutants from material delivery and storage to the stormwater system or watercourses by minimizing the storage of hazardous materials onsite, storing materials in a designated area, and installing secondary containment. The contractor should establish an area away from all storm drainage facilities and natural drainage courses for the storage of chemicals such as paints, adhesives solvents or curing compounds, storage of petroleum products such as fuels for vehicles and construction equipment. The contractor shall set aside an area for concrete truck washing where all concrete debris and affected soil may be removed upon completion of the project. d) Utilities All required utilities (except for sanitary sewer) are along the property within the public right-of-way. The contractor shall construct a unified trench for all utilities ensuring appropriate separation between utilities. No utilities will be installed prior to installation of the erosion sediment control facilities. Excavated trench material shall be placed upstream of the silt fence. The excavated material may not be placed outside the silt fence perimeter or against the filter fence. e) Organization Responsible for Maintenance The owner or his/her designated person(s) of the proposed development will be responsible to maintain the storm drainage facilities. The type and frequency of long-term maintenance of the drainage facilities are presented below. Cost of maintaining shall be entirely with the owner and a budgeted amount should be included within their annual budgeting schedule. Brandon Lee Short plat Storm Drainage Report 1-4 July 2008 fj Catch Basins Catch basins should be inspected for sediment build-up, structural damage, and pollution. Catch basins should be inspected once a year, and if more than one-third of the depth to the invert is silted, cleaning should be conducted. Secondly, the catch basin should be inspected for structural damage on the order of every 10 years. Attention is needed if the frame is out of flush by 3/4-inch, cracks are evident in walls, settlement is noticed, or rotation occurs. Since the catch basins may be located in traffic areas, structural damage is likely. Thirdly, the catch basins should be inspected for pollution each year. g) Vegetation Management Plan Vegetation around the proposed building will be grass. This normal garden grass to be planted will be determined by the owner recommendations. Management of the grass will consist of mowing, but will also include selective thatching, aerating, and reseeding as needed. Brandon Lee Short Plat Storm Drainage Report 1-5 July 2008 ATTACHMENT: EXHIBIT A: Existing Site Conditions EXHIBIT B: Proposed Site Conditions EXHIBIT C: Erosion Control EXHIBIT D: Erosion Control Details 6 1 c I D I E I F I G H K PROTECT EXILING CATCH BASIN WITH INLET PROTECTION PROTECT DRIVEWAY L A IN A 3'! PROTECT EXISTING BUILDINGti T_ 77 L % PROTECT EXI51•1 % WATER ME "x \j TOP OF STEEP SLOPE 25, SL ACK LJNEo x WETLAND DELINEATION UNE---/ k E`C�__' !.N!' (N% �F= PROTECT EXIS TING- BUILDING it F jj ...... . .. . . ... .. . ....... . . ....... ... .. Ail 0 20 40 VSCALE IN FEET NHAN VO 1922 ARAB DRIVE SE, OLYMPIA, WA Phone: (360) 943-2108 0ESCRIPT10N Ig VERIFY SCALE PAR IS HALT INCH ON ORKWAL DRAWING EXHIBIT A DATE: XNE 15. 2OOL__ 0 - 0.5' PROJECT NO. F Nor nkf INCH ON THIS SHErl, EXISTING SITE CONDITIONS ADXST SCALES ACCOF&HCLY REVISION NO. DRAWN: DV 2709 TALBOT ROAD SOUTH, RENTON, WASHINGTON DESIGNED: NDV — APPLICANT:• BRANDON LEE SHT NO. OF I CHECKVEVV. IFIAi R 618 PASCO PLACE NE, RENTON, WASHINGTON DWG NO. c_S APPROD. IE m r.-I 7 6 5 4 3 2 A B_ c D E F G H I J K L mi I N _t 0 1 ;_l SITE SURFACING NOTES: 10 ... . ... .... . .. . ... . ... 1. 7W EM7W _qW SOLS REWWRE PROPER COMPACTION PRIOR TO . . . . ... . . . ............ ... .. . . ..... .. PLACEMENr OF BtXDK PAVI% AM UnUrY IMPROVOWiM N, S REPAIR / REP[ACE ALL DOSTING FACLITIES THAT ARE COMIlvem 70 OAIAWED DLIRM CON911R)OTION TO PRE-CONSTFAICTION CONDnION. CONTRACIOR TO MWW 2 FEET CRUM SETRAM M AU PROPERLY LIDS J_ 9 r '0, L J 0 0 r J T E ESV, EX BUILDING PROPOSEDTyp. LOTLJN TO REMAIN T Zii 7"� DNt' Krv", r� GAS W bE J� 7 41 '4, A� 41 4. 3/4"rWA7ER SERVICE P.R.V.� PER W 3 4 gy I� RENITO� CITY V, -Z -a ai Z 4CONNtCT TO Ext WATER T? -5- LINE PER CITY OF JRENTON STANDARDS 24' GAS VICE TO )BE • -,,PROPOSED PROVIDED BY LOCAL 77, :-GAS TWPANY P, BUILDING' 6PICAMOW, l0kcF0 .24' WIDE SINGLE FAMILY RESIDENTIAL DRIVAY b PER CITY OF RE �STANDARDS CONNECT J TO EX. F LINE PER C17Y 0 RENTON STANDARD� ZWETLAND AREA L'25' STEEP SLCIPE, SETBACK LINE] ---------- 6� EWER LATERAL DER 4 Ty OF RENTON % STEEP SLOPE AREA Ifi TAX LO-T No. 30`,2,0;5 STANDARDS )ii z "'C") 4�'A ES!A No, 9-15091 24" DRIVEWAY 4 FIRE HYDRANT 30d RADIUS LINE WETLAND AREA .3 BOUNDARY . . . . . . . . . ..... . .... . .. . .. ... ... .............................. . . .... ... . . . ........ . .... ------- 2 0 20 40 rI t SCALE IN FEET 1�a VERIFY SCALE EXHIBIT B DATE: SEPT� 15. 2007 NAR M HALF INCH ON ORIGINAL ORhriMG NHAN VO 0 - ILI PROJECT NO. F NOT HALF INCH ON THIS SHEET. PROPOSED CONDITIONS ADJUST SUJXS ACCOMNGLY REVISION NO. 1922 ARAB DRIVE SE, OLYMPIA, WA -DRAWN: Nnv 2709 TALBOT ROAD SOUTH, RENTON, WASHINGTON Phone: (360) 943-2108 DENGNED: NOY APPLICANT: BRANDON LEE SHT NO. I OF I REV DESCRIPTtQN BY CHECKED: RR 618 PASCO PLACE NE, RENTON, WASHINGTON DWG NO, 2700 PRE-APPLE;wc REVISIONS APPROVED: 13L A DESCRIPTION A a K I L m I N i 0 PROTECT EX1s71NG CATCH BASIN WITH INLET PROTEC71ON R 1 H FL II )r V I 'L'3 PROTECT EXISTING BUILDING A • - r"l Z % % .................. N 51 DUI (Vi) E 1 ;41.0 PRO CT E)Os-nNG WATER IAETEk f L-L CONMUCTION ENTRANCE v m V% ssmi-i RN L— W2.113 + PROTECT EXISTING BUILDING F N HAN VO 1922 ARAB DRIVE SE, OLYMPIA, WA Phone: (360) 943-2108 20 4c WALE IN FEET VERIFY SCALE EXHIBIT C BAR IS 14AU ApCm am ORDINAL ORAI 0 r 0.57 IF NOT HALF INCH ON THIS SHEET. TEMPORARY ERONSION CONTROL AMST StQ.ES ACCOOON(Xy DRAWN: Nov - 2709 TALBOT ROAD SOUTH, RENTON. WASHINGTON Dumm: —Nov L- APPLICANT: BRALNDON LEE CHECKED: as 618 PASCO PLACE NE, RENTON, WASHINGTON APPROVED: BL_ DATE: SEPT. 10, 2DO7 PROJECT NO. REVISION NO. SHI NO. 1 OF I DING NO. 0 A 9 5 4 3 6 I NOTES: I. FILTER FABRIC SHALL BE PURCHASED IN A CONTINUOUS ROLL AND CUT TO THE LENGTH OF THE BARRIER TO AVOID USE OF JOINTS. WHEN JONTS ARE NECESSARY, FILTER CLOTH SHALL BE SPLICED TOGETHER ONLY AT A SUPPORT POST, WITH A MINIMUM 6-INCH OVERLAP, AND SECURELY FASTENED AT BOTH ENDS TO POSTS. Z POSTS SHALL BE SPACED A MAXIMUM OF 6 FEET APART AND DRIVEN SECURELY INTO THE GROUND (MINIMUM OF 30 INCHES). S, A TRENCH SHALL BE EXCAVATED APPROXIMATELY B INCHES WIDE AND T2 INCHES DEEP ALONG THE LINE OF POSTS AND UPSLOPE FROM THE BARRIER. THIS TRENCH SHALL BE BACKFILLED WITH WASHED GRAVEL. 4. WHEN STANDARD STRENGTH FILTER FABRIC IS USED, A WIRE MESH SUPPORT FENCE SHALL BE FASTENED SECURELY TO THE UPSLOPE SIDE OF THE POSTS USING HEAVY-DUTY WIRE STAPLES AT LEAST 1-INCH LONG, TIE WIRES OR HOG RINGS. THE WIRE SHALL EXTEND INTO THE TRENCH A MINIMUM OF 4 INCHES AND SHALL NOT EXTEND MORE THAN 24 INCHES ABOVE THE ORIGINAL GROUND SURFACE. 5. THE STANDARD STRENGTH FILTER FABRIC SHALL BE STAPLED OR WIRED TO THE FENCE, AND 20 INCHES OF THE FABRIC SHALL BE EXTENDED INTO THE TRENCH. THE FABRIC SHALL NOT EXTEND MORE THAN 24 INCHES ABOVE THE ORIGINAL GROUND SURFACE. FILTER FABRIC SHALL NOT BE STAPLED TO EXISTING TREES. 6. WHEN EXTRA -STRENGTH FILTER FABRIC AND CLOSER POST SPACING IS USED, THE WIRE MESH SUPPORT FENCE MAY BE ELIMINATED. IN SUCH A CASE, THE FILTER FABRIC IS STAPLED OR WfREO DIRECTLY TO THE POSTS WITH ALL OTHER PROVIVOINS OF ABOVE NOTES APPLYING. 7. FILTER FABRIC FENCES SHALL NOT BE REMOVED BEFORE THE VPSLOPE AREA FINS REIN PERMANENTLY STABILIZED. 6. FILTER FABRIC FENCES SHALL BE INSPECTED IMMEDIATELY AFTER EACH RAINFALL AND AT LEAST DAILY DURING PROLONGED RAINFALL. ANY REQUIRED REPAIRS SHALL BE MADE IMMEDIATELY. 9_ SILT FENCES WILL BE INSTALLED PARALLEL TO ANY SLOPE CONTOURS. 10. CONTRIBUTING LENGTH TO FENCE WILL NOT BE GREATER THAN 700 FEET. 11. DO NOT INSTALL BELOW AN OUTLET PIPE OR WEIR. 12. INSTALL OOWNSLOPE OF EXPOSED AREAS. 13. DO NOT DRIVE OVER OR FILL OVER SILT FENCES. FILTER FABRIC MATERIAL WIRE MESH SUPPORT IN CONTINUOUS ROLL USf FENCE FOR FILTER STAPLES OR WIRE RINGS FABRIC TO ATTACH TO FABRIC TO WIRE. r- Q' "K5' WOOD 9 POSTS. STANDARD N OR BETTER OR EOUNELANT. r Z'x2"n5' WOOD POSTS. STANDARD L�V9I[QN OR BETTER OR EQUIVFLANi FILTER FABRIC MATERIAL - WASHED GRAVEL BACKFILL, 3/4•-3' IN TRENCH AND ON BOTH SIDES OF FILTER "' o FABRIC 1 UNI FILTER MATERIAL IN B"s12" 8• i x TRENCH AND LEAVE MINIMUM 2" n EXPOSED. nnCAL CROSS SECTION SIL TA TION FENCE SCALE: NTS DESCRIPTION F H l5 4' TO B" QUARRY SPALLS, 12' MIN. THICKNESS PROVIDE FULL WIDTH OF INGRESS/EGRESS CONSTRUCTION ENTRANCE SCALE: NTS RETRIEVAL STRAP ADAPTER SKIRT A '% CB GRATE CS INSERT - SEE NOTE I OVERFLOW (TO BYPASS PEAK FLOWS) SEDIMENT ACCUMULATOR O.5CF CAPACITY, MIN. CB INLET PROTECTION NOTES: 1. CATCH BASIN INSERT TO BE ULTRA-ORAINGUARD ITEM/9226 (PLASTIC ENGINEERED PROOLICTS CO.. I-BOD-407-3726), OR APPROVED EOLNVALENT, 2. FILTERS SHALL BE REMOVED AND CLEANED OR REPLACED AFTER EACH STORM EVENT. CB INSERT PROTECTION SCALE: NTS N HAN VO 2:1 MAX, SLOPE DIKE MATERIAL COMPACTED 2 MIN TO 95X MODIFIED PROCTOR — !j�18- MIN. _I __6' MIN. 1 I r INTERCEPTOR DIKE SPACING =100', 200'. OR 300' DEPENDS ON SLOPE GRADIENT INTERCEPTOR D1KES GRASS OR ROCK 2:1 MAX. SLOPE LEVEL BOTTOM / II i' MIN. 11L I 1 2' WIN - I —I 1922 ARAB DRIVE SE, OLYMPIA, WA Phone: (360) 943-2108 SCALE/DITCH SPACING =100'. 2DO', OR 3DO' DEPENDS ON SLOPE GRADIENT INTERCEPTOR SWALES TEMPORARY SWALES AND DIKES SCALE: NTS VERIFY SCALE BAR IS "AV NQI ON ORHIIK& DRAWING a as IF NOT HALF INCH ON THIS SHEET, AMUST SCALES ACCORDINGLY DRAWN: Nov DESIGNED: -,..NDV CHECKED: BB AS A B� B N A EARTH @FAIN flAC{ 6" MIN, F 10 EARTH BERM - FILTER FABRIC 9 5/8" MINUS / WASHED ROCK SECTION B-19 �- EX. CROUND TOP OF DIKE 6" MIN. EX. GROUND SECTION 3- GRAVEL OUTLET STRUCTURE SCALE: NTS EXHIBIT D ERONSION CONTROL DETAILS 2709 TALBOT ROAD SOUTH, RENTON, WASHINGTON APPLICANT: BRANDON LEE 618 PASCO PLACE NE, RENTON, WASHINGTON CALL UTILITIES LOCATOR 48 HOURS PRIOR TO DIGGING 1-800-424-5555 0 IFA 6 5 4 3 2 DATE: SEPT. 10. 2007 1 PRWECT NO. REVISION NO. SHT NO. 7 OF DWG NO. G-7 APPENDIX A: Technical Information Report (TIR) Geotechnical Study Wetland Studies and Delineation Page 1 of 2 King County Building and Land Development Division TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Project Owner l3LArf*AQQkJ LE7e Address 61?A,$(-0 p A C O 14C Phone _(d7s Project EngineerANI V0 Company Address Phone 14 ZZ &fit. 5C.0"Mrip ngpehI 12f..1 /Ic!_ "7%q Q Subdivision Short Subdivision Grading Q Commercial Q Other Community Tmo l Drainage Basin Q River [ Stream Q Critical Stream Reach Q Depressions/Swales Q Lake Steep Slopes Lakeside/Erosion Hazard i So'IT i Al�9I�pe 10-%41,1 ear Project Name FNZAt4Do*► LEG SHORT MI Location 270 'CALM % D S. Rom` OP UAN Township 210 Range 57I Section 130 Project Size .St 2S`t �IF AC t►t AC. Upstream Drainage Basin Size AC Q DOF/G HPA Q COF 404 Q DOE Dam Safety Q FEMA Floodplain Q COE Wetlands Floodplain Wetlands Seeps/Springs High Groundwater Table Groundwater Recharge Other Q Shoreline Management Q Rockery Q Structural Vaults Other Q HPA s� Slopes Erosion Potential Erosive Velocities E] Additional Sheets Attatched M Page 2 of 2 0 0 0 0 0 King County Building and land Development Division TECHNICAL INFORMATION REPORT (TIR) WORKSHEET REFERENCE LIMITATION/SITE CONSTRAINT Ch. 4 - Downstream Analysis y1t, t We—Z,; l5 MitAe i , roe s ..P' AIfe•AV- "N OFf La>N ICAD t. A LPP �Oftft L10 t IMP 4: TO DOW#-)-129ftA R- , Additional Sheets Attatched MINIMUM ESC REQUIREMENTS MINIMUM ESC REQUIREMENTS DURING CONSTRUCTION FOLLOWING CONSTRUCTION Sedimentation Facilities © Stabilize Exposed Surface ® Stabilized Construction Entrance EJ Remove and Restore Temporary ESC Facilities Perimeter Runoff Control ® Clean and Remove All Silt and Debris I� Clearing and Grading Restrictions ® Ensure Operation of Permanent Facilities ® Cover Practices 0 Flag Limits of NGPES E:1 Construction Sequence 0 Other [::1 Other PART i SURFACE WATER SYSTEM ® Grass Lined Channel 1:1 Tank [XI Infiltration Method of Analysis X1 Pipe System 0 Vault 0 Depression S6L)4 Open Channel 0 Energy Dissapator 0 Flow Dispersal Compensation/Mitigation Dry Pond Wetland 0 Waiver of Eliminated Site Storage 0 Wet Pond Stream 0 Regional Detention Brief Description of System Operation Of (2.001F Wp oFF f M 4 N r _ _ CDUN T%( T Nn Facility Related Site Limitations Additional Sheets Attatched Reference Facility Limitation 0 Cast in Place Vault Other Retaining Wall C] Rockery>4'High 0 Structural on Steep Slope I or a civil engineer under my supervision have visited the site. Actual site conditions as observed were incorporated into this worksheet and the attatchments. To the best of my knowledge the information provided here is accurate. Drainage Easement Access Easement [] Native Growth Protection Easement [� Tract Other 1/90 Basin: OFF -SITE ANALYSIS DRAINAGE SYSTEM TABLE Surface Water Design Manual, Core Requirement #2 Subbasin Name: Subbasin Number: Symbol D:ainage. Drainage Cor pc�nent',i.. Slope `; >Distance Existing Potential . ;' Observations;0 field'irispector Ccrnpbnenf TYpa.; bes riptirrn from site: Problems Problems ' resource r vo wer, or resident ' t«farri{e��ar�d :Size .. ... ! disclisr a 1ype;sheet:llow svrak,'_ . q,y i,1,/e L'BP :.Oohding1.::` see:m8p : str�rtr :ahanhd.,: w*:' i#Ah* lrtg"Oh, t r, 96 /4 #�t} :1,?f2o ft oveftoppEnp; noodtng, FiabRak tir drganhsitii "fi wtary area, MWIS11w of >robkm. pond `size dianstter depth type er�saffr >arEai volume demnKfim. t i ftbank abughtr .' > ovet0ow pathways; poter al impacia • .. :ra Btli�Faceareer <<,:: :<:: >;: "-.' .. . >.;: ;- ;;> . ... :>. r;^ aedimentatien: #ncfs6en:;afhar'erasion :,'r .. OTabie,doc IV2192 OFF -SITE ANALYSIS DRAINAGE SYSTEM TABLE Surface Water Design Manual, Core Requirement #2 Basin: Crystal Drainage Basin Subbasin Name: Clear Creels Subbasin Number: AA Symbol, Drainer :;' Qrair apd. amponent. : ; Slope Distance.::.Existing Poteniklal Otyseryatians �f field inspector• , Cnt: Type,< a3rnpon e C?oscnptit►rr from.site Problems Problems resource reviewer, or resident :. Name acid Sire:<r :. dischar dt: Type. sheet fkrirx aanrare., c6nstnctio�s ender ca #ingA. Pay she map '. dart, eftanrtet, pipe, dry ti>3sln, Via►, rdver, 96 fId mi 91 32Q R ovet6opping. floatting, habftet or �rganlem tt�uteiy area, �kdihood of pro�te t,. . pond;. S1ze: diameter. deptl i tYP4 at:aeneaflve ewer. voturr�c destn�ction scovrin9, bad stoughfng, : overflow pathways.. potential Orr acts: auitaoe area „.. sedimentation Inch ion-athererosion > A Site Discharge Crystal Drainage Basin 0' Location A - B Natural Swale Natural, dense vegetation 2% 0 - 249 None None Swale has capacity; no erosion exists. B - C 12" CMP Under private drive 240' - 260' None Under capacity No erosion exists 3% 1 C - D Draw Natural, dense vegetation 8% 260' - 500' Erosion Further erosion Tributary area about 650 - 1900 acres D - E 18" CMP Under 57th Street 6% 500' - 660' None Under capacity Overtopping is unlikely. If culvert were plugged, drainage would flow toward roadside ditch. E - F Seasonal stream Natural, dense vegetation 5% 660' - 860' None None No erosion exists. with gravel and sand at the flow line G - H 36" RCP Under 15th Street 5% 860' - 1010' None Under capacity No erosion exists. H - 1 36" RCP Under 1-22 3% 1010' - 1160' None Under capacity No erosion exists. I - J 36" RCP Adjacent to Smith Street 1.5% 1160' -1310' Flooding and Under capacity No erosion exists. Sedimentation J - K Clear Creek Type 2 Stream 1.5% 1310' - 1610' Erosion Further erosion No erosion exists. K - L Wetland CL21 Type 2 Wetland 1610' - 1660' Tributary area 15 sq. mi. L - M Crystal Lake 1660' L1Table.doc 11r2M Geotechnical Engineering Date: 6-20-07 HGE Construction Inspections Project: Lee Talbot Prop CONSULTING Retaining Structures File #: 34-007 Materials Testing June, 25 2007 SUBSURFACE EXPLGRATIGN AND G EGTECHNICAL ENGINEERING REPORT Brandon Lee 2709 Talbot Road South Renton,WA. Prepared for Brandon Lee 618 Pasco Place NE Renton, WA. Geotechnical Engineering Date: 6-20-07 HGE Construction Inspections Project: Lee Talbot Prop CONSULTING Retaining Structures File #: 34-007 op Materials Testing Mr. Brandon Lee Project Address: 2709 Talbot Road South 618 Pasco Place NE. Renton, WA Renton, WA. Parcel#: 3023059036 Re: Subsurface Exploration/Geotechnical Engineering Report Attn: Mr. Brandon Lee: At your request, we have conducted a soils exploration and foundation evaluation for the above mentioned project. The results of this investigation, and our recommendations, are to be found in the following report. We have provided three copies for your review and distribution. During our exploration, four test holes were dug and soil samples submitted for laboratory testing from the project site. The data has been carefully analyzed to determine soils bearing capacities, slope stability, and footing embedment depths. The results of the exploration and analysis indicate that conventional spread and continuous wall footings appear to be the most suitable type of foundation for the support of the proposed structures. Net allowable soil pressures, embedment depth, soil parameters, and total expected settlements have been presented for the site, later in the report. Often, because of design and construction details that occur on a project, questions arise concerning soil conditions. We would be pleased to continue our role as geotechnical engineers during the project. We appreciate this opportunity to be of service to you and we look forward to working with you in the future. If you have any questions concerning this report, the procedures used, or if we can be of any further assistance please call us at (253)405-4654. Respectfully, HGE CONSULTING Jamie C. Hicks Jason E.C. Bell, P.E. President Geotechnical Engineer 907 Orting-Kapowsin Hwy., Orting, WA 98360 Page 2 of 24 Phone: 253-405-4654 Email: jamiehicks50@msn.com Geotechnical Engineering Date: 6-20-07 HGE Construction Inspections Project: Lee Talbot Prop CONSULTING Retaining Structures File #: 34-007 -0 Materials Testing Table of Contents Table of Contents Investigation Information Introduction: Scope: General: Site Exploration Procedures General Notes: Drilling & Sampling Procedures: Laboratory Testing Program: _ Site Information 3 4 4 4 6 7 7 7 7 8 Project Description 8 Climate of Area: 8 Geology of Area: (AgC) and (AgD) Alderwood Gravelly Sandy loam soils 8 Description of Foundation Materials: 9 Geoseismic Setting: 9 Liquefaction Potential: 9 Foundation Discussion & Recommendations 11 General Notes: 11 Foundation Design Recommendations: 11 Structural Fill: 12 Percolation Rate: 13 Groundwater Control: 13 Lateral Earth Pressures: 13 Slope Recommendations: 14 Slope Impact Analysis: 14 Building Setback 14 Construction Considerations 15 Earthwork: 15 Excavations: 15 Floor Slab -On -Grade: 15 Erosion Conclusion APPENDIX I VICINITYMAP APPENDIX II SITE PLAN LVITHBORING LOG LOCATIONS APPENDIX III BORING LOG APPENDIX IV LAB TESTING APPENDIX V LIQUEFACTION MAP 907 Orting-Kapowsin Hwy., Orting, WA 98360 I Page 3 of 24 Phone: 253-405-4654 Email: jamiehicks50@msn.com 16 17 i8 18 20 20 22 22 23 23 24 24 Geotechnical Engineering Date: 6-20-07 HGE Construction Inspections Project: Lee Talbot Prop CONSULTING Retaining Structures File #: 34-007 op Materials Testing Investigation Information Introduction: This report presents the results of a soils exploration and foundation analysis for the proposed new short plat located at 2709 Talbot Road South in Renton, WA. The subsurface exploration and analysis determines the various soil profile components, the engineering characteristics of the foundation materials, the appropriate slope setbacks, and provides criteria for the design engineers and architects to prepare or verify the suitability of the foundation design. This report was requested by Mr. Brandon Lee. Verbal authorization to perform this exploration and analysis was provided by Mr. Brandon Lee Scope: The scope of this geotechnical report and analysis included; a review of geological maps of the area, review of geologic and related literature, a reconnaissance of the immediate site, subsurface exploration, field and laboratory testing, and an engineering analysis and evaluation of the foundation materials to provide allowable bearing capacity, estimates of settlement, lateral earth pressure design values, geotechnical recommendations for slope setbacks, site grading including site preparation, subgrade preparation, fill placement criteria, suitability of on -site soils as structural fill, drainage and erosion control measures, as well as an evaluation of landslide and erosion hazards at the site per the King County Critical Areas regulations and the City of Renton Municipal Code Section 4- 3-050 Critical Areas Ordinance. King County -City of Renton Erosion Hazard An erosion hazard area is defined in the King County critical areas ordinance 15051 as an area underlain by soils that are subject to severe erosion when disturbed. These soils include, but are not limited to, those classified as having a severe to very severe erosion hazard according to the United States Department of Agriculture Soil Conservation Service, the 1973 King County Soils Survey or any subsequent revisions or addition by or to these sources, such as any occurrence of River Wash ("Rh") or Coastal Beaches ("Cb") and any of the following when they occur on slopes inclined at fifteen percent or more: Alderwood gravely sandy loam ("AgD"); Alderwood and Kitsap soils ("AkF"); Beausite gravely sandy loam ("BeD" and "BeF"); Kitsap silt loam ("KpD"); Ovall gravely loam ("OvD" and "OvF"); Ragnar fine sandy loam ("RaD"); Ragnar-Indianola Association ("RdE"). The site is classified by the USDA as having an erosion hazard of "moderate", for the Alderwood gravelly sandy loam (AgQ on the east portion of the site, The other portion of the site (west) is classified by the USDA as having Alderwood gravelly sandy loam (AgD) soils with slopes between 35 -40%. According to the United States Department of Agriculture Soil Conservation Service, the 1973 King County Soils Survey the AIderwood gravelly sandy loam soils (AgD) are listed as having a severe erosion hazard. The City of Renton Municipal code section 4-3-050 J.1.c give the definition of an erosion hazard. Erosion hazards are classified in one of two categories, Low Erosion Hazard (EL) or High Erosion Hazard (EH). The criteria for Low Erosion Hazard (EL) are areas with soils characterized by the Department of Agriculture Soil Conservation Service as having slight to moderate erosion potential, and that slope less than 15 percent. The criteria for High Erosion Hazard are areas with soils characterized by the Department of Agriculture Soil Conservation Service as having severe or very severe erosion potential, and that slope more steeply than 15 percent. The City of Renton Municipal Code (RMC) also provides an erosion hazard map RMC Figure-4-3-050Q3c(i). The hazard map includes the City of Renton and shows graphically throughout the city where high erosion hazards are present. 907 Orting-Kapowsin Hwy., Orting, WA 98360 I Page 4 of 24 Phone: 253-405-4654 Email: jamiehicks5O@msn.com Geotechnical Engineering Date: 6-20-07 HGE Construction Inspections Project: Lee Talbot Prop CONSULTING Retaining Structures File #: 34-007 Materials Testine According to the above stated criteria for both King County Critical Areas and the Renton Municipal Code Critical Areas. The project site is found to be an erosion hazard area (King County) or a High Erosion Hazard (EH) (City of Renton). Landslide Hazard Area Ordinance 10870, Section 176, and K.C.C. 21A.06.680 defines a Landslide Hazard Area as an area subject to severe risk with the following criteria: A. An area with a combination of: 1. Slopes steeper than fifteen percent of inclination; 2. Impermeable soils, such as silt and clay, frequently interbedded with granular soils, such as sand and gravel; and 3. Springs or ground water seepage; B. An area that has shown movement during the Holocene epoch, which is from ten thousand years ago to the present, or that is underlain by mass wastage debris from that epoch; C. An area potentially unstable as a result of rapid stream incision, stream bank erosion or undercutting by wave action; D. An area that shows evidence of or is at risk from snow avalanches; or E. An area located on an alluvial fan, presently or potentially subject to inundation by debris flows or deposition of stream -transported sediments. The City of Renton Municipal Code (RMC) Section 4-3-050J- Geologic Hazards categorizes a landslide hazard into one of four categories. The Landslide Hazards are classified as either a Low Landslide Hazard (LL), Medium Landslide Hazard (LM), High Landslide Hazard (LH), or Very High Landslide Hazards (LV). The landslide hazards are defined as follows: Low Landslide Hazard (LL)- Areas having slopes less than 15 percent. Medium Landslide Hazard (LM)- Areas having slopes between 15 and 40 percent and are underlain by soils that consist largely of sand, gravel, or glacial till. High Landslide Hazard (LH)- Areas with slopes greater than 40 percent or areas with slopes between 15 and 40 percent and underlain by soils consisting largely of silt and clay. Very High Landslide Hazard (LV)- Area of known mappable landslide deposits. King County Critical Areas: A) Sloped areas are steeper than 15% and the lower layers are mostly comprised of compact glacial till, however they do not appear to be interbedded with granular soils or gravel and no springs or seeps were noted on site during the site visit. B) No evidence of slippage or movement was noted during the site visit. During the Quaternary, the Puget Lowland was covered a number of times by continental ice sheets. The most recent (Fraser) glaciation reached its peak about 14,000 years ago. Holocene deposits are typically younger than the end of either the Fraser or Wisconsin glaciations, depending on the location. The site consists of glacial till which indicates that it was below the large ice sheets from the Frasier Glaciations. C) The site does not sit near a stream or moving water course that can cause stream incision or possible erosion. D) There are no risks from snow avalanches on site. E) The site soils consist of Alderwood ("AgC" and "AgD") gravely sandy loam soils. These soils were not formed in alluvium and do not appear to be subject to inundation by debris flow or stream -transported sediments. Renton Municipal Code Critical Areas: According to the Renton Municipal Code Critical Areas- Geologic Hazards section the Landslide Hazard for the site is listed as a Medium Landslide Hazard (LM). The site has slopes up to 40 percent and it is underlain by the Alderwood gravelly sandy loam till soils ("AgC" and "AgD"). 907 Orting-Kapowsin Hwy., Orting, WA 98360 Page 5 of 24 Phone: 253-405-4654 Email: jamiehicks50@msn.com Geotechnical Engineering Date: 6-20-07 HGE Construction Inspections Project: Lee Talbot Prop CONSULTING Retaining Structures File #: 34-007 Materials Testing We were not requested to provide an Environmental Site Assessment for this property. Any comments concerning onsite conditions and/or observations, including soil appearances and odors, are provided as general information. Information in this report is not intended to describe, quantify or evaluate any environmental concern or situation. General: The exploration and analysis of the foundation conditions reported herein are considered sufficient in detail and scope to form a reasonable basis for the foundation design. If deviations from the noted subsurface conditions are encountered during construction, they should also be brought to the attention of the soils engineer. The soils engineer warrants that the findings, recommendations, specifications, or professional advice contained herein, have been promulgated after being prepared according to generally accepted professional engineering practice in the fields of foundation engineering, soil mechanics and engineering geology. No other warranties are implied or expressed. This investigative report has been prepared for the exclusive use of Brandon Lee and retained design consultants thereof. Findings and recommendations within this report are for specific application to the proposed project. All recommendations are in accordance with generally accepted soils and foundation engineering practices. 907 Orting-Kapowsin Hwy., Orting, WA 98360 Page 6 of 24 Phone: 253-405-4654 Email: jamiehicks50@msn.com Geotechnical Engineering Date: 6-20-07 HGE Construction inspections Project: Lee Talbot Prop CONSULTING Retaining Structures File #: 34-007 -0 Materials Testing Site Exploration Procedures General Notes: The field exploration to determine the engineering characteristics of the onsite soils included a reconnaissance of the project site, excavating the test holes, and recovering disturbed grab samples. A total of four test holes were placed on the site. Test holes were advanced up to 5.5 feet below the existing ground surface. Test holes were located by the field crew to provide a cross section for the three lots. Brandon Lee's planning consultant supplied a site plan, to locate the proposed lots orientation and position the excavations. The test holes locations are shown on the site plan in Appendix II. The types of onsite native materials encountered in the test holes have been visually classified and described in detail on the test hole logs provided in Appendix III. The results of the moisture contents and other laboratory tests are presented in the laboratory testing section found in Appendix IV. It is recommended that the logs not to be used for estimating quantities due to highly interpretive results. Drilling & Sampling Procedures: The test holes were performed with a track excavator. Representative samples were obtained from the holes at various soil intervals. The samples obtained by this procedure were classified in the field by a soils technician, identified according to test hole number and depth, placed in plastic bags to protect against moisture loss and transported to the laboratory for additional testing. Laboratory Testing Program: Along with the field investigation, a supplemental laboratory testing program was conducted to determine additional pertinent engineering characteristics of the onsite materials necessary in analyzing the behavior of the proposed construction. The laboratory testing program included supplementary visual classification on all samples. In addition, selected samples were subjected to Grain Size Analysis - ASTM designation C-117, C-136. All phases of the laboratory testing program were conducted according to applicable ASTM Specifications and the results of these tests are to be found on the accompanying laboratory testing section located in the Appendix IV. 907 Orting-Kapowsin Hwy., Orting, WA 98360 I Page 7 of 24 Phone: 253-405-4654 Email: jamiehicks50®msn.com Geotechnical Engineering Date: 6-20-07 Ask HGE Construction Inspections Pr_ oject: Lee Talbot Prop CONSULTING Retaining Structures File #: 34-007 VW Materials Testing Site Information Project Description The purpose of this section is to enumerate details of the proposed construction. The following information was provided by Mr. Brandon Lee's planning consultant. The lot currently has a house and a garage structure onsite. The proposed construction will be the short platting of the one larger lot into three subsequent building lots and the construction of three houses, one per each lot. No construction details have been given for any of the structures so it is assumed that the construction will consist of conventional spread footings and slab -on -grade floors. Differential settlements are limited to 3/ inch. A pavement section will not be required since the structures are to be accessed by private or shared private driveways. The site topography consists of a semi -flat, 0-5% slope, front yard that slopes to the west, away from Talbot Road South. The slope then increases to 40% at the rear of the garage and continues to the west until it flattens out on the western portion of the property. The relief of the site is approximately 80 feet. The site vegetation consists of lawn in the front (east) and side (south) of the structure, second growth timber with areas of alder, cottonwood, maple, and fir trees on the sloped portion of the site (west of the structure). The underbrush consists of blackberry bushes, ferns, salal, and vine maple. Climate of Area: The climate of the site and surrounding area as taken from the USDA Soil Conservation Service Survey consists of annual precipitation of 35 to 60 inches, most of which is rainfall, between October and May. The mean annual temperature is about 50 degrees F. The frost free season is 150 to 200 days. Geology of Area: (AgC) and (AgD) Alderwood Gravelly Sandy loam sails The Alderwood (AgC) and (AgD) soils are both Alderwood soils that vary mainly because of their slopes. The soils formed in the same manner and are very similar however they do have differences due to their slope inclination. Both soil types will be described in the following section. The geology of the area as compared to the "USDA Soil Conservation Service (SCS), Soil Survey of King County Area, Washington. 1973" was consistent with the materials found onsite. The area is mapped as an Alderwood gravelly sandy loam (AgC) 6-15% slopes or an (AgD) 15-30% slopes. The Alderwood gravelly sandy loam soils are moderately well drained and have a weakly to strongly consolidated substratum. The Alderwood soils formed in glacial till deposits on broad uplands. The existing topography, as well as the surfrcial and shallow subsurface soils in the area are the result of the most recent Vashon stade of the Frasier glaciations of 12,000 to 15,000 years ago, and weathering and erosion that has occurred since. The site soils are part of the Alderwood-Everett Association. The Alderwood gravelly sandy loam soils typically form in zones of glacial till and have a, slow to medium (AgC) and medium (AgD), surface runoff, and create a, moderate (AgC) and severe (AgD) erosion hazard. We observed no evidence of seeps onsite, however seeps are very common with this soil type due to a perched water table above the very slowly permeable, weakly cemented, and compact substratum during periods of heavy rainfall. We observed no signs of active erosion or slope disturbance on the parcel. There are no signs of active bluff retreat onsite either. The Alderwood (AgC) and (AgD) gravelly sandy loam soils have the inherent ability to support large loads. The primary limitation for urban development are slope and the weakly cemented substratum generally associated with this soil type. 907 Orting-Kapowsin Hwy., Orting, WA 98360 I Page 8 of 24 Phone: 253-405-4654 Email: jamiehicks50®msn.com Geotechnical Engineering Date: 6-20-07 HGE Construction Inspections Project: Lee Talbot Prop CONSULTING Retaining Structures File #: 34-007 Materials Testing Description of Foundation Materials: The soil profiles encountered were consistent among the four holes. The soils were found to consist of Alderwood soils in all 4 test holes. It is to be noted that, whereas the test holes were placed and sampled by an experienced technician, it is sometimes difficult to record changes in stratification within narrow limits. It is recommended that the test hole logs are not to be used for estimating quantities due to highly interpretive results. The surface of the proposed construction site is covered with 6 to 12 inches of topsoil or forest duff that should be removed prior to the start of any construction due to the high compressibility of these soils. In all areas the Alderwood soils were encountered beneath the existing topsoil and extended to depths beyond the scope of this investigation. Lines of demarcation represent the approximate boundary between the soil types, but the transition may be gradual. The site soils showed minor signs of mottling at depths of 24"48" in the test holes. Mottled soil indicates seasonal soil saturation (alternate oxidizing and reducing conditions). In other words, water flows through this layer periodically creating a saturated soil condition at times and at other times the soil may be dry. This can create a soft, saturated yard area, problems for basements and septic fields, and poor aeration for landscape plantings. Implementation of perimeter footing drains should alleviate many difficulties associated with these soil conditions. Geoseismic Setting. This project site is classified as a Site Class C per the 2003 International Building Code (I.B.C.) from Table 1615.11. All building structures on this project should be designed per the Code Requirements for such a seismic classification. These types of soils have a shear wave velocity in the range of 1,200 to 2,500 ft/sec and undrained shear strength greater than 2000 psf with blow counts greater than 50 blows per foot. The following may be used for the seismic coefficients. Design Response Spectrum 120.00 5 100.00 s0.00 s F- ai 60.00 40.00 s 20.00-- 0.00 0.00 0.20 0.40 0,00 03D 1.00 1.20 1.40 Period, T Liquefaction Potential: Seismic Coefficient Z=0.3 C, 0.33 C, 0.45 Period, T Sa 0 0.00 40.00 To 0.05 100.00 Ts 0.26 100.00 1 1.00 26.00 2 2.00 13.00 Liquefaction is when saturated, cohesionless soils are temporarily turned in to a liquid state usually from a seismic event. If ground motion lasts for extended amounts of time, the grain to grain contact shifts and the grain structure can collapse. If the water within the soil cannot flow easily between the grain and out of a collapsing area, the water pressure increases. When pore pressures build up within the soil and exceed the effective contact pressure of the soil, the water can push the soil particles apart. When the particles lose contact with each other, the soil mass can behave like a liquid. If pore pressures are great enough, water may discharge out of the ground Iike a geyser leaving characteristic signs, such as sand boils. Liquefaction is generally related to; soil characteristics, water table 907 Orting-Kapowsin Hwy., Orting, WA 98360 I Page 9 of 24 Phone: 253-405-4654 Email: jamiehicks50®msn.com Geotechnical Engineering Date: 6-20-07 HGE Construction Inspections Project: Lee Talbot Prop CONSULTING Retaining Structures File #: 34-007 Materials Testing depths and the degree of seismic activity. The results are lower bearing capacities, increased settlement issues, landslides, and lateral spreading to name a few things. Liquefaction potential for this site is provided within the boundaries of the site. In our review we found no evidence of liquefaction of the soils in the immediate area from the 1949, 1965 and 2001 earthquakes. In review of the King County Liquefaction Susceptibility Map produced by the Washington State Department of Natural Resources, the project site was classified as very low to low liquefaction susceptibility. A copy of the applicable portion of the map and the map legend are located in the Appendix V. 907 Orting-Kapowsin Hwy., Orting, WA 98360 Page 10 of 24 Phone: 253-405-4654 Email: jamiehicks50@msn.com Geotechnical Engineering Date: 6-20-07 HGE Construction Inspections Project' Lee Talbot Prop CONSULTING Retaining Structures File #: 34-007 Materials Testing Foundation Discussion & Recommendations General Notes: Various foundation types have been considered for the support of the proposed building structures. Two requirements must be fulfilled in the design of foundations. First, the load must be less than the ultimate bearing capacity of the foundation soils to maintain stability; and secondly, the differential settlement must not exceed an amount that will produce adverse behavior of the superstructure. The allowable settlement is usually exceeded before bearing capacity considerations become important; thus, the allowable bearing pressure is normally controlled by settlement considerations. Considering the subsurface conditions and the variability of the proposed construction since each lot may have different owners with different home designs. It is recommended that each structure be evaluated separately using the recommendations contained within this report. The following recommendations are an overall generalization assuming a structure that is single story and that requires a bearing capacity of no more than 1800 psf, if the structures differ from this we recommend that a geotechnicai professional review the structure and provide recommendations. Using our generalization of a single story structure and 1800 psf requirement, it is recommended that the structure be founded upon conventional spread and continuous wall footing foundations. Settlements should not exceed tolerable limits if the following design and construction recommendations are observed. Foundation Design Recommendations: On the basis of the data obtained from the site and the test results from the various laboratory tests performed, we recommend that the following guidelines be used for the net allowable soils bearing capacity. All footings are to be excavated to native undisturbed soils. Footings are required to be a minimum of 18 inches below grade for freeze thaw purposes. After excavation, compact the surface with a jumping jack compactor. Confirm compaction of the native soils and that all soft spots have been removed and replaced with suitable fill material and compacted to least 95% of the maximum dry density as determined by ASTM D-1557. All footings are to be excavated at least 2 feet below final grade due to the increased bearing capacity of the soils on the site at depths. Footings are required to be a minimum of 18 inches below grade for freeze thaw purposes. f Continuous wall footings should be a minimum of 18 inches in width and any slab for the proposed building should be suitably reinforced and connected to the footings so as to limit the effects of differential settlement and to provide some degree of uniform settlement ability for the building should the site undergo liquefaction during a major seismic event. 907 Orting-Kapowsin Hwy., Orting, WA 98360 I Page 11 of 24 Phone. 253-405-4654 Email: jamiehicks50®msn.com Geotechnical Engineering Date: 6-20-07 HG E Construction Inspections Project: Lee Talbot Prop CONSULTING Retaining Structures File #: 34-007 Materials Testing Ground Surface ---..I -� --� -- Perimeter Footing Drain 18.0 inch min. Perforated, 6 inch pipe required for freeze -thaw Footing Depth: 18 inches 18.0 inches min. width Net Allowable Footing Bearing Capacity: 2,000 PSF Native Bearing (Approx): 2,000 PSF I The footings should be proportioned to meet the stated bearing capacity and/or the International Building Code 2003 minimum requirements. Total settlement should be limited to 1 inch total with differential settlement of 3/ inch. Any excessively loose or soft spots or areas that do not meet the compaction requirements that are encountered in the footing subgrade will require over -excavation and backfilling with at least 1 foot of structural fill. In order to minimize the effects of any slight differential movement that may occur due to variations in the characters of the supporting soils and any variations in seasonal moisture contents, it is recommended that all continuous footings be suitably reinforced to make them as rigid as possible. Structural FiII: Structural fill should consist of a 3 inch minus select, clean, granular soil with no more than 5% fines (4200). Suitable structural fill should consist of material that meets one of the following specifications, WSDOT Section 9- 03.10 Aggregate for Gravel Base, WSDOT Section 9-03.14(1) Gravel Borrow, WSDOT Section 9-03.14(2) Select Borrow, WSDOT Section 9-03.9(3) Crushed Surfacing (Base Course Specs), WSDOT Section 9-03.9(3) Crushed Surfacing (Top Course Specs), APWA Class A Pit Run, or APWA class B Pit Run. Material that does not meet one of the specifications should be submitted with sieve analysis results for approval prior to placement. The fill should be placed in lifts not to exceed 12 inches in loose thickness. Each layer of structural fill should be compacted to a minimum density of 95% of the maximum dry density as determined by ASTM designation D-1557. For structural fill below footings, the area of the compacted backfill must extend outside the perimeter of the foundation for a distance at least equal to the thickness of the fill between the bottom of the foundation and the underlying soils. If it is elected to utilize a compacted backfill for the support of foundations, the subgrade preparation and the placing of the backfill should be monitored continuously by a qualified engineer or his representative so that the work is performed according to these recommendations. The use of on -site soils as structural fill is not recommended during wet weather. These materials require very high moisture contents for compaction and require a long time to dry out if natural moisture contents are too high. This makes moisture content, lift thickness, and compactive effort difficult to control. 907 Orting-Kapowsin Hwy., Orting, WA 98360 I Page 12 of 24 Phone: 253-405-4654 Email: jamiehicks50@msn.com Geotechnical Engineering Date: 6-20-07 HGE Construction Inspections Project: Lee Talbot Prop CONSULTING Retaining Structures File #: 34-007 Materials Testing Percolation Rate: In -situ percolation tests were not performed on the site. However the "USDA Soil Conservation Service (SCS), Soil Survey of King County Area, Washington. 1973" has Table 2 which provides "Estimated Properties" of the soils in the King County Soil Survey. The following is a table of the permeability properties of the site soils at a depth of 23" as found in Table 2 USDA Soil Conservation Service (SCS), Soil Survey of King County Area, Washington. 1973 Soil Type Rate: inches per hour Ave. Depth to <.06 in/hr Alderwood 2.0-6.3 1 27" Groundwater Control: Groundwater was not encountered when the field exploration was conducted. Groundwater is not expected to cause difficulties during construction of this project. It is recommended that runoff caused by wet weather be directed away from all open excavations. The on -site sandy loam soils can be expected to become soft and pump if subjected to excessive traffic after becoming wet during periods of bad weather. This can be avoided by constructing temporary or permanent driveway sections should wet weather be forecast. The on -site drainage (roof drains & catch basins for pavement areas) should be collected and directed away from the property. This can be accomplished by tight -lining the drainage to the city approved storm drainage system or to an onsite infiltration system. If retaining walls or basements are proposed all retaining or basement walls should contain at least 12 inches of free draining material behind the wall as well as a 6 inch perforated drainpipe at the bottom of the wall to alleviate any pressure buildup. Connect the drainpipe to the on site storm drainage system or to the city approved storm system. It is recommended that all structures have footing drains placed around the perimeter of the structures. These drains can be tight lined and connected to the storm drainage system or the city storm system, if available. Lateral Earth Pressures: Lateral earth pressures are dependent upon the backfill materials and their configuration and moisture content. Three inch minus sand and gravel mixtures that are free draining are recommended for backfilling walls greater than four feet tall. Below grade retaining walls or walls designed for retaining earthen fills on this project may use the following values for design. Values were obtained by using unit weight of 126.6 pcf, and phi angle of 37 degrees. Earth Pressure Coefficients Active, Ka: 0.249 At Rest, Ka: 0.398 Passive, KP: 4.023 Earth Pressure Active: 31 lbs./ft3 At Rest: 50 lbs./ft3 Passive: 509 lbs./ft3 Coefficient of Friction: 0.40 907 Orting-Kapowsin Hwy., Orting, WA 98360 Page 13 of 24 Phone: 253-405-4654 Email: jamiehicks50@msn.com Geotechnical Engineering Date: 6-20-07 HGE Construction Inspections Pr- okect: Lee Talbot Prop CONSULTING Retaining Structures File #: 34-007 op Materials Testing Slope Recommendations: We recommend that the proposed structures be built using a minimum setback of 25 feet from the top of the slope to the east. This may be reduced depending on the design of the proposed structures and the possible change of footing type. This reduction of slope setback must be evaluated by a geotechnical engineer with the specific proposed house plans for each building lot. The slope to the west of the proposed building pads currently shows no signs of bluff retreat and/or erosion. To maintain this stability it is our recommendation that the site slope remain vegetated with the natural vegetation. Slope Impact Analysis: We do not anticipate that the proposed residential structures and construction of the project will have any off -site impacts. On -site care should be taken during construction to make sure that runoff caused by wet weather is directed away from all open excavations and site slopes. The site is stable enough to support the proposed residential construction within the recommendations made herein. Building Setback Based on our geotechnical evaluation of the site and our experience in the area, we believe that the structures may be built with a minimum setback (including buffers) of 25 feet total from the top of the western slope. This may be reduced by a geotechnical engineer using site specific information in the future. The site is stable in relation to deep seated failures. As previously discussed, weathering, erosion and resulting surface sloughing and shallow land sliding are natural processes that effect slope areas. As noted no evidence of surface raveling or sloughing was observed in the sloping portions of the site. To manage and reduce the potential for these natural processes, we recommend no drainage of concentrated surface water or significant sheet flow onto or near the slope area. Drainage from the roof area should be collected and tight lined to the infiltration system or city approved system. No filling within the buffer or setback zone unless retained by engineered retaining walls or constructed as an engineered fill. 907 Orting-Kapowsin Hwy., Orting, WA 98360 I Page 14 of 24 Phone: 253-405-4654 Email: jamiehicks50®msn.com Geotechnical Engineering Date: 6-20-07 HGE Construction Inspections nroject: Lee Talbot Prop CONSULTING Retaining Structures File #: 34-007 1) Materials Testing Construction Considerations Earthwork: Excessively organic top soils generally undergo high volume changes when subjected to loads. This is detrimental to the behavior of pavements, floor slabs, structural fills and foundations placed upon them. It is recommended that excessively organic top soils be stripped from these areas to depths of 6-12 inches and wasted or stockpiled for later use. Exact depths of stripping should be adjusted in the field to assure that the entire root zone is removed. It is recommended that the final exposed subgrade be inspected by a representative of the soils engineer. This inspection should verify that all organic material has been removed. Any soft spots or deflecting areas should be removed to sound bearing and replaced with structural fill. Once the existing soils are excavated to the design grade, proper control of the subgrade conditions (i.e., moisture content) and the placement & compaction of new fill (if required) should be maintained by a representative of the soils engineer. The recommendations for structural fill presented within this report, can be utilized to minimize the volume changes and differential settlements that are detrimental to the behavior of footings, and floor slabs. Enough density tests should be taken to monitor proper compaction. For structural fill beneath building structures one in -place density test per lift for every 1,000 ft2 is recommended. In parking and driveway areas this can be increased to two tests per lift for every 3,000 ft2. Excavation equipment may disturb the bearing soils and loose pockets can occur at bearing levels that were not disclosed by the test holes. For this reason, it is recommended that the bottoms of the excavations be compacted in - place by vibratory compactors. The upper 12 inches should be recompacted to achieve an in -place density of not less than 95% of the maximum dry density as determined by ASTM D-1557. Excavations: Shallow excavations required for construction of foundations that do not exceed four feet in depth may be constructed with side slopes approaching vertical. Below this depth it is recommended that slopes not exceed one vertical to one horizontal. For deep excavations, the soils present cannot be expected to remain in position. These materials can be expected to fail, and collapse into any excavation thereby undermining the upper soils materials. This is especially true when working at depths near the water table. Proper care must be taken to protect personnel and equipment. Care roust be taken so that all excavations made for the foundations are properly backfilled with suitable material compacted according to the procedures outlined in this report. Before the backfill is placed, all water and loose debris should be removed from these excavations. This information is provided for planning purposes. It is our opinion that maintaining safe working conditions is the responsibility of the contractor. Jobsite conditions such as soil moisture content, weather condition, earth movements and equipment type and operation can all affect slope stability. All excavations should be sloped or braced as required by applicable local, state and federal requirements. Floor Slab -On -Grade: Before the placing of concrete floors or pavements on the site, or before any floor supporting fill is placed, the organic, loose or obviously compressive materials must be removed. The subgrade should then be verified by the geotechnical engineer or his representative that all soft or deflecting areas have been removed. Areas of excessive yielding should be excavated and backfilled with structural fill. 907 Orting-Kapowsin Hwy., Orting, WA 98360 Page 15 of 24 Phone: 253-405-4654 Email: jamiehicks50@msn.com Geotechnical Engineering Date: 6-20-07 HGE Construction Inspections Project: Lee Talbot Prop CONSULTING Retaining Structures File #. 34-007 - 4) Materials Testing Any additional fill used to increase the elevation of the floor slab should meet the requirement for structural fill. Structural fill should be placed in layers of not more than 12 inches in thickness, at moisture contents at or above optimum, and compacted to a minimum density of 95% of the maximum dry density as determined by ASTM designation D-1557. A granular mat should be provided below the floor slabs. This should be a minimum of four inches in thickness and properly compacted. The mat should consist of sand or a sand and gravel mixture with non -plastic fines. All material should pass a 3/ inch sieve and contain less than 10% passing the #200 sieve. Groundwater can be expected at shallower depths during the winter months. A moisture barrier, such as 10 mil visqueen or 10 mil plastic sheeting, may be placed beneath all floor slabs. Erosion Control It is our opinion that the potential erosion hazard is not a limiting factor for the proposed construction. At the time of our original site visit the original vegetation was still on the site. The site was vegetated with grasses, blackberry bushes, and trees. Temporary erosion control measures may be necessary during construction. Permanent erosion control measures are required as soon as they are feasible to install. Temporary erosion control measures may include, plastic covering, temporary seeding, surface roughening, mulching, and matting. Permanent erosion control measures may include permanent seeding and planting, sodding, surface roughening, and topsoiling then seeding. Permanent erosion control should be established on the site as soon as possible. 907 Orting-Kapowsin Hwy., Orting, WA 98360 Page 16 of 24 Phone: 253-405-4654 Email: jamiehicks50@msn.com Geotechnical Engineering Date: 6-20-07 HGE Construction Inspections Project: Lee Talbot Prop CONSULTING Retaining Structures File #: 34-007 1P Materials Testing Conclusion The results of the geotechnical investigation that was performed for this project has indicated that the site is classified under the Renton Municipal Code Critical Areas definitions, as a High Erosion Hazard (EH) and Medium Landslide Hazard (LM). These however do not appear to be a limiting factor that would affect the construction of the three new residences on the three parcels. Overall the site is suitable for the proposed construction. Without the specific house plans for each individual lot it is proposed that the building setback from the top of the slope to the west shall be 25 feet (including buffer) unless it is reduced by a geotechnical engineer. If you have any questions concerning the test results, the procedures used, or if we can be of any further assistance please call on us at (360) 893-0045. 907 Orting-Kapowsin Hwy., Orting, WA 98360 Page 17 of 24 Phone: 253-405-4654 Email: jamiehicks50@msn.com Geotechnical Engineering Date: 6-20-07 HGE Construction Inspections Project: Lee Talbot Prop CONSULTING Retaining Structures File #: 34-007 Materials Testing VICINITY MAP 907 Qrting-Kapowsin Hwy., Orting, WA 98360 Page 18 of 24 Phone: 253-405-4654 Email: jamiehicks50@msn.com HGE MW CONSULTING IFFM Geotechnical Engineering j Date: 6-20-07 Construction Inspections Pr.--oject: Lee Talbot Prop Retaining Structures File #: 34-007 Materials Testing 907 Orting-Kapowsin Hwy., Orting, WA 98360 Page 19 of 24 Phone: 253-405-4654 Email: jamiehicks50@msn.com Geotechnical Engineering HGE Construction Inspections CONSULTING Retaining Structures Materials Testier APPENDIX II Date: 6-20-07 Project: Lee Talbot Prop File #: 34-007 SITE PLAN WITH BORING LOG LOCATIONS 907 Orting-Kapowsin Hwy., Orting, WA 98360 Page 20 of 24 Phone: 253-405-4654 Email: jamiehicks50®msn.com HGE op CONSULTING Geotechnical Engineering I Date: 6-20-07 Construction Inspections Project: Lee Talbot Prop Retaining Structures File #: 34-007 Materials Testin, 907 Orting-Kapowsin Hwy., Orting, WA 98360 Page 21 of 24 Phone: 253-405-4654 Email: jamiehicks5D@msn.com ANA HGE JW CONSULTING Geotechnical Engineering Date: 6-20-07 Construction Inspections Project: Lee Talbot Prop Retaining Structures File #: 34-007 Materials APPENDIX III BORING LOG 907 Orting-Kapowsin Hwy., Orting, WA 98360 I Page 22 of 24 Phone: 253-405-4654 Email: jamiehicks50@msn.com Geotechnical Engineering Date: 6-20-07 HGE Construction Inspections Project: Lee Talbot Prop CONSULTING Retaining Structures File #: 34-007 op Materials Testine APPENDIX IV LAB TESTING 907 Orting-Kapowsin Hwy., Orting, WA 98360 Page 23 of 24 Phone: 253-405-4654 Email: jamiehicks50®msn.com Geotechnical Engineering Date: 6-20-07 HGE Construction Inspections Project: lee Talbot Prop CONSULTING Retaining Structures File #: 34-007 . Materials Testing APPENDIX V LIQUEFACTION MAP 907 Orting-Kapowsin Hwy., Orting, WA 98360 Page 24 of 24 Phone: 253-405-4654 Email: jamiehicks50@msn.com 3i WATERSHED October 8, 2007 Brandon Lee 618 Pasco Place NE Renton, WA 98055 brandonlee618 @ yahoo.com Re: Wetland Delineation Study, TWC Ref# 070926 Dear Mr. Lee: S C I E N C E & D E 5 I G N On October 3, 2007, The Watershed Company Ecologists Nell Lund and Meagan McManus conducted a wetland delineation study on the property located at 2709 Talbot Road South in the City of Renton (parcel 3023059036). This letter summarizes the findings of this study and details applicable federal, state, and local wetland regulations. The following attachments are included: • Wetland Delineation Sketch • Wetland Determination Data Forms Methods The subject property was evaluated for wetlands using methodology from the Washington State Wetlands Identification and Delineation Manual (Manual) (Washington Department of Ecology [Ecology] 1997). Wetland boundaries were determined on the basis of an examination of vegetation, soils, and hydrology. Areas meeting the criteria set forth in the Manual were determined to be wetland. Soil, vegetation, and hydrologic parameters were sampled at several locations on the property to make the determination. We recorded data at four of these locations. Wetlands are marked with pink- and black -striped flags. Wetland A and is marked with 9 flags. Data points are marked with yellow- and black -striped flags. On -site wetlands are classified using the revised Western Washington Wetland Rating System (Ecology, Aug 2004, version 2). Field and aerial photos from King County's mapping website (iMAP) were used in conjunction with data collected on -site to rate the wetlands. Findings 750 Sixth Street South Kirkland, WA 98033 p 425.822.5242 j' 425.827.8136 watershedco.com Brandon Lee October 8, 2007 Page 2 of 3 The subject property is located in the City of Renton north of Panther Lake and east of Highway 167 in the Cedar River/Lake Sammamish watershed (WRIA 8). The property consists of a house and mowed backyard area on the eastern portion of the property, steep forested slopes in the center, and a large flat wetland area on the western boundary. The subject wetland (Wetland A) is part of a 73-acre system of depressional and riverine areas known as Panther Creek Wetlands. Wetland A is characterized by very dark grayish brown loamy clay soils (10YR3/2) with dark yellowish brown (10YR4/6) redoxomorphic features (RMFs). At 12", the soils contain clay inclusions, which are gleyed (10Y5/1) with yellowish brown (10YR5/8) RMFs. Vegetation is dominated by reed canary grass (Pholaris arundinacea) with Oregon ash (Fraxinus latifolia), Himalayan blackberry (Rubus armeniacus) and cattails (Typha latifolia) also present. The soil was saturated to the surface at the time of our visit. The steep -sloped non -wetland forested area east of Wetland A is characterized by soils ranging from very dark brown (10YR2/2) to dark yellowish brown (10YR4/4) sandy loams and very dark grayish brown (10YR3/2) sandy clay loams with no RMFs. Dominant vegetation includes snowberry (Symphoricarpus albus), Himalayan blackberry and scouring rush (Equisetum hyemale). Other vegetation observed on the slope includes big -leaf maple (Ater macrophyllum) and Oregon ash (Fraxinus latifolia). Vegetation east and south of the house in the yard area is dominated by climbing nightshade (Solanum dulcamara) and English ivy (Hedera helix) with apple trees (Malus spp.), Himalayan blackberry and domestic grape vines (Vitis spp.) also present. Saturation was observed within the top inch of the soil at all non -wetland data sites, likely due to heavy rainfall at the time of our visit. The soils at all data sites were dry at a depth of 10". Local Regulations The City of Renton regulates wetlands with its own classification system according to Renton Municipal Code (RMC) Section 4-3-050 Chapter 3 Section M. Wetland A is a Category 2 wetland according to RMC.3.M.ii.c, being a wetland "of any size located at the headwaters of a watercoursc", noting its association with southerly flowing streams. Standard buffer widths for a Category II wetland in the City of Renton are 50 feet as measured from the wetland boundary as surveyed in the field (RMC 4-3-050.3.M.6.b&c). Steep slopes between 25-40% as defined in figure 4-3-050Q3e(i) of RMC were observed on the property abutting the delineated wetland boundary to the east. Additionally, on -site slopes may satisfy the criteria for high erosion and landslide hazard areas according to RMC figures 4-3-050Q3b(i) & 4-3-050Q3c(i)). According to RMC 4-3-0503.M.6.d.ii & iii, such areas may have their buffers increased to protect wetland functions and values. A representative of the City of Renton makes this determination. Upon your request, standard buffer widths may be altered in accordance with RMC 3-4-050.6 through buffer averaging or reduction. Buffer averaging may be allowed if the applicant demonstrates that such averaging will not adversely impact the wetland functions and values, the total area contained within the averaged wetland buffer is no less than that contained within the required standard buffer prior to averaging and the buffer is not reduced by more than fifty (50%) of the standard buffer or less than twenty-five feet (25'). A site -specific evaluation and documentation of buffer adequacy must be conducted according to best available science as Brandon Lee October 8, 2007 Page 3 of 3 described in Washington Administrative Code 365-195-905. Standard buffer widths may be reduced upon approval if the applicant can demonstrate compliance with a buffer enhancement plan using native vegetation in which the enhanced buffer will be equal to or improve the functional attributes of the existing buffer. Buffer enhancement shall not result in greater than a twenty-five percent (25%) reduction in the buffer width. State and Federal Regulations Wetlands are also regulated by the U.S. Army Corps of Engineers (Corps) under section 404 of the Clean Water Act. Any filling of Waters of the State, including wetlands (except isolated wetlands) would likely require notification and permits from the Corps. The Corps would not consider Wetland A isolated. Federally permitted actions that could affect endangered species (i.e. salmon or bull trout) may also require a biological assessment study and consultation with the U.S. Department of Fish and Wildlife and/or the National Marine Fisheries Service. Application for Corps permits may also require an individual 401 Water Quality Certification and Coastal Zone Management Consistency determination from Ecology. Please note that the findings of this letter, including wetland classification and resulting buffer width predictions, are subject to the verification and agreement of local, state, and/or federal regulatory authorities. Please call if you have any questions or if we can provide you with any additional information Sincerely, Meagan McManus Ecologist Enclosures Wetland Delineation Sketch (parcel number 3023059036) TWC # 070926 City of Renton, Washington Prepared for Brandon Lee October 4, 2007 Tl I F WATE€ SHED CC)%1 PANY 750 Sixth Street South Kirkland ' WA 98033 p 425,822.5242 425.827.8136 WATERSHED WETLAND DETERMINATION DATA FORM 750 Sixth Street South Kirkland, Washington 98033 (425) 822-5242 Fax (425) 827-8136 WATERSHED WETLAND DETERMINATION DATA FORM 750 Sixth Street South Kirkland, Washington 98033 (425) 822-5242 Fax (425) 827-8136 WETLAND? YES Date: October 3, 2007 Data point: DP-1 Wetland # : A Project Name: _Lee Property Data point location: North property edge (See sketch) Biologist(s): NL, MNI Do normal environmental conditions exist . YES NO Has vegetation, soils &/or hvdrolopv been sip aptly disturbed within the past 5 yrs? YES NO Stratum: T=tree. S=shrub, H=herb, V=vine VEGETATION Dominant Species Stratum WIS Other Species Stratum WIS Rubus armeniacus S FACU Fraxinus latifolia T FACW S m horicar us albus S FACU Rubus laciniatus V FACU+ E uisetum h emale H FACW Po! stichum munitum H FACU Percent of dominant species that are FAC, FACW or OBL 33% Vegetation criteria met? YES NO Other observed tree vegetation outside of data point area includes big -leaf Notes: maple (Ater macrophyllum). SOILS Mottles Depth Horizon Matrix Color (UsfincyPromneni) Texture 1-16" B 10YR2/2 None Sandy loam Soil Criteria Met? YES Notes: Surface saturation? Q NO Depth to saturation N/A Depth of inundation NIA Depth to free in pit N/A Flow? YES Channel? Sheet? HYDROLOGY Primary Indicators: (1 required) Observation of inundation _ Observation of soil saturation Water marks Drift lines or drainage patterns Sediment deposits Hydric indicators: Gleyed/Low Chroma Sulfidic odor Histosol Other (list in notes) Secondary Indicators: (>2 required) Oxidized root channels Water -stained leaves _ Local soil survey data FAC-neutral test Hydrologic Criteria Met? YES (�D Recent rainfall: Very high High Normal Low Very low Notes: * Top --1" saturated by recent rainfall. No satur " elow. WILDLIFE OBSERVATIONS AND GENERAL NOTES FF WETLAND DETERMINATION DATA FORM WATERSHED 750 Sixth Street South Kirkland, Washington 98033 (425) 822-5242 Fax (425) 827-8136 WETLAND? YES NO Date: October 3, 2007 Project Name: Lee Property Biologist(s): NIL, MM Do normal environmental conditions exist? Has vegetation, soils Wor hydrology been Data point: DP-2 Wetland # : A Data point location: West of DP-1 (See sketch) Stratum: T=tree, S=shrub, H=herb, V=vine VEGETATION Dominant Species Stratum WIS Other Species Stratum WIS Phalaris arundinacea H FACW Fraxinus latifolia T FACW Rubus armeniacus S FACU Typha latifolia H O B L Percent of dominant species that are FAC, FACW or OBL 100% Vegetation criteria met? YES NO Notes: SOILS Matrix Mottles Depth Horizon Color DistinctlProOnenl Texture Hydric Indicators: 2-16" B 10YR 3/2 10YR416 Loamy clay Gleyed/Low Chroma 12-16" Inclusions 10Y5/1 10YR5/8 Clay Sulfidic odor Soil Criteria Met? YES NO Notes: Surface saturation? Q NO Depth to saturation 0" Depth of inundation N/A Depth to free water in pit NIA Flow? YES NO Channel? Sheet? HYDROLOGY Primary Indicators: (1 required) Observation of inundation Observation of soil saturation _ Water marks _ Drift lines or drainage patterns Sediment deposits Hydrologic Criteria Met NO Notes: Histosol Other (list in notes) Secondary Indicators: (?2 required) _ Oxidized root channels Water -stained leaves Local soil survey data FAC-neutral test Recent rainfall: Very high High Normal WILDLIFE OBSERVATIONS AND GENERAL NOTES Low Very low i E > WATERSHED WETLAND DETERMINATION DATA FORM 750 Sixth Street South Kirkland, Washington 98033 (425) 822-5242 Fax (425) 827-8136 _ WETLAND? YES NO Date: October 3, 2007 Data point: DP-3 Wetland # : A Project Name: Lee Property Data point location: East of wetland flags A-6 and A-7 Biologist(s): MM, NIL Do normal environmental conditions exist? YES NO Has vegetation, soils &/or hydrology been sig ' ' ntly disturbed within the past 5 rs? YES NO ,Stratum: T=tree, S=shrub, H=herb, V=vine VEGETATION Dominant Species Stratum WIS Other Species Stratum WIS Rubus armeniacus S FACU E uisetum telmateia H FACW Percent of dominant species that are FAC, FACW or OBL 0% Vegetation criteria met? YES NO Notes: SOILS Depth...- Horizon Matrix Color Mottles p (uis,incuPromnen„ Texture 1-12" B 10YR312 None Sandy clay loam Soil Criteria Met? Notes: Surface saturation?CDNO Depth to saturation NIA Depth of inundation NIA Depth to free water in pit NIA Flow? YES NO Channel? Sheet? HYDROLOGY Primary Indicators: (i required) _ Observation of inundation _ Observation of soil saturation Water marks Drift lines or drainage patterns T Sediment deposits Hydric Indicators: Gleyed/Low Chroma Sulfidic odor Histosol Other (list in notes) Secondary Indicators: (>_2 required) Oxidized root channels Water -stained leaves Local soil survey data FAC-neutral test Hydrologic Criteria Met? YES NO Recent rainfall: Very high High Normal Low Very low Notes: * Only ton-1 " saturated due to recent rainfall. WILDLIFE OBSERVATIONS AND GENERAL. NOTES WETLAND DETERMINATION DATA FORM WATERSHED Date: October 3, 2007 Project Name: Lee Property Biologist(s): MM, NL 750 Sixth Street South Kirkland, Washington 98033 (425) 822-5242 Fax (425) 827-8136 WETLAND? YES Data point: DP-4 Wetland # : A Data point location: South corner of backyard Stratum: T=tree, S=shrub, H=herb, V=vine VEGETATION Dominant Species Stratum WIS Other Species Stratum WIS Solanum dulcamara H FAC+ Malus gpp. T NL Hadera helix H NL Rubus armeniacus S FACU Vitis s . V NL Percent of dominant species that are FAC, FACW or OBL 50% Vegetation criteria met? YES NO Notes: SOILS Depth Horizon Matrix Color Mottles Texture ofslincWromhnen, 10" B 10YR4/4 None Sandy foam Soil Criteria Met? YES Notes: Surface saturation? (Q) NO Depth to saturation NIA Depth of inundation N/A Depth to free water in pit NIA Flow? YES NO Channel? Sheet? Hydrologic Criteria Met? Notes: * O HYDROLOGY Primary Indicators (1 required) Observation of inundation Observation of soil saturation _ Water marks _ Drift lines or drainage patterns Sediment deposits YES NO Recent rainfall: --1 /4" saturated. Very high Hydric Indicators: Gleyed/Low Chroma Sulfidic odor Histosol Other (list in notes) Secondary Indicators: (?2 required) Oxidized root channels Water -stained leaves Local soil survey data FAC-neutral test Low Very low WILDLIFE OBSERVATIONS AND GENERAL NOTES Apple trees, holly tree, non-native conifer and ornamental shrubs, Himalayan blackberry, lawn grass, dandelion and Robert's geranium present. APPENDIX B: General Soils Map Hydrologic Soil Group SCS Western Washington Runoff Curve Numbers Soil Map —King County Area, Washington (2709 Talbot Road South) N Meters A 0 16 20 40 50 Feet 0 45 90 IN 270 6DA Natural Resources Web Sail Survey 2.0 81111200$ Conservation Service National Cooperative Soil Survey Page 1 of 3 MAP LEGEND Area of Interest (A01) Area of Interest (AO I) Soils Soil Map Units Special Point Features v Blowout N Borrow Pit x Clay Spot Closed Depression X Gravel Pit Gravelly Spot Landfill A, Lava Flaw Marsh Mine or Quarry O Miscellaneous Water O Perennial Water v Rock Outcrop + Saline Spot Sandy Spot Severely Eroded Spot 0 Sinkhole 3 Slide or Slip Sodic Spot Spoil Area 1) Stony Spot Soil Map —King County Area, Washington (2709 Talbot Road South) Very Stony Spot Wet Spot a Other Special Line Features Gully Short Steep Slope r'. Other Political Features Municipalities O Cities 0 Urban Areas Water Features Oceans Streams and Canals Transportation Rails Roads �. Interstate highways US Routes State Highways N Local Roads Other Roads MAP INFORMATION Original soil survey map sheets were prepared at publication scale. Viewing scale and printing scale, however, may vary from the original. Please rely on the bar scale on each map sheet for proper map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: http:llwebsoilsurvey.nrrs.usda.gov Coordinate System: UTM Zone 10N This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: King County Area, Washington Survey Area Data: Version 4, Nov 21, 2006 Date(s) aerial images were photographed: 7/1011990: 711 all 990 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. USDA Natural Resources Web Soil Survey 2.0 811112008 Conservation Service National Cooperative Soil Survey Page 2 of 3 Soil Map —King County Area, Washington Map Unit Legend 2709 Talbot Road South King County Area, Washington (WAB33) Map unit Symbol Map Unit Name Acres in AOI Percent of AOl AgC Aldervrood ravell sand Io 0.4 35.1 % 6 to 5 percent slopes AgD Alderwood rave oam 0.5 40.6°% 15 to 30 percent slopes Sk Seattle muck 0.3 24.3°% Totals for Area of Interest (AO I) 1.2 100.0% Ls � us Natural Resources Web Soil Survey 2.0 8111/2008 Conservation Service National Cooperative Soil Survey Page 3 of 3 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL (2) CN values can be area weighted when they apply to pervious areas of similar CN's (within 20 CN points). However, high CN areas should not be combined with low CN areas (unless the low CN areas are less than 15% of the subbasin). In this case, separate hydrographs should be generated and summed to form one hydrograph. FIGURE 3.5.2A HYDROLOGIC SOIL GROUP OF THE SOILS IN KING COUNTY SOIL GROUP HYDROLOGIC GROUP* SOIL_ GROUP HYDROLOGIC GROUP" Alderwood s� L_s:� Orcas Peat D rents, Aderwood Material C Oridia D Arents, Everett Material B Ovall C Beausite C Pilchuck C Bellingham D Puget D Briscot D Puyallup B Buckley D Ragnar B Coastal Beaches Variable Renton D Eadmont Silt Loam D Riverwash Variable Edgewick C Sala! C Everett A /B I-Sammamish D Indianola A Seattle D Kitsap C Shacar D Klaus C Si Silt C Mixed Alluvial Land Variable Snohomish D Neilton A Sultan C Newberg B Tukwila D Nooksack C Urban Variable Normal Sandy Loam D Woodinville D HYDROLOGIC SOIL_ GROUP CLASSIFICATIONS A. (Low runoff potential). Soils having high infiltration rates, even when thoroughly wetted, and consisting chiefly of deep, well -to -excessively drained sands or gravels. These sails have a high rate of water transmission. B. (Moderately low runoff potential). Soils having moderate Infiltration rates when thoroughly wetted, and consisting chiefly of moderately fine to moderately coarse textures. These soils have a moderate rate of water transmission. C. (Moderately high runoff potential). Soils having slow infiltration rates when thoroughly wetted, and consisting chiefly of soils with a layer that impedes downward movement of water, or soils with moderately fine to tine textures. These soils have a slow rate of water transmission. D. (High runoff potential). Soils having very slow infiltration rates when thoroughly wetted and consisting chiefly of clay soils with a high swelling potential, soils with a permanent high water table, soils with a hardpan or Gay layer at or near the surface, and shallow soils over nearly impervious material. These soils have a very slow rate of water transmission. From SCS, TR-55, Second Edition. June 1986, Exhibit A-1. Revisions made from SCS, Soil Interpretation Record, Form #5, September 1988. 3.5.2-2 11192 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL TABLE 3.5.213 SCS WESTERN WASHINGTON RUNOFF CURVE NUMBERS SCS WESTERN WASHINGTON RUNOFF CURVE NUMBERS (Published by SCS in 1982) Runoff curve numbers for selected agricultural, suburban and urban land use for Type 1A rainfall distribution, 24-hour storm duration. CURVE NUMBERS BY HYDROLOGIC SOIL GROUP LAND USE DESCRIPTION A 8 C D Cultivated land(i): winter condition 86 91 94 95 Mountain open areas: low growing brush and grasslands 74 82 89 92 Meadow or pasture: 65 78 85 89 Wood or forest land: undisturbed or older second growth 42 64 76 81 Wood or forest land: young second growth or brush 55 72 81 86 Orchard: with cover crop 81 88 92 94 Open spaces, lawns, parks, golf courses, cemeteries, landscaping. good condition: grass cover on 75% or more of the area 68 W 90 fair condition: grass cover on 50% to 7S% of the area 77 85 90 92 Gravel roads and parking lots 76 85 89 91 Dirt roads and parking lots 72 82 87 89 Impervious surfaces, pavement, roofs, etc. 98 98 W 98 Open water bodies: lakes, wetlands, ponds, etc. 100 100 100 100 Single Family Residential (2) Dwelling Unit/Grass Acre % Impervious (3) 1.0 DU/GA 15 Separate curve number 1.5 DU/GA 20 shall be selected 2.0 DU/GA 25 for pervious and 2.5 DU/GA 30 impervious portion 3.0 DU/GA 34 of the site or basin 3.5 DU/GA 38 4.0 DU/GA 42 4.5 DU/GA 46 5.0 DU/GA 48 5.5 DU/GA 50 6.0 DU/GA 52 6.5 DU/GA 54 7.0 DU/GA 56 Planned unit developments, % impervious condominiums, apartments, must be computed commercial business and Industrial areas. (1) For a more detailed description of agricultural land use curve numbers refer to National Engineering Handbook, Section 4, Hydrology, Chapter 9, August 1972. (2) Assumes roof and driveway runoff is directed into street/storm system. (3) The remaining pervious areas (lawn) are considered to be in good condition for these curve numbers. & 3.5.2-3 11/92 APPENDIX C: Level Spreader Calculations Conveyance Facility Design Calculations Roof Drainage Calculations KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL FIGURE 4.5.6A DOWNSPOUT DISPERSION TRENCH °ODo O O° PD 00 a !� D pO G 0 G O O P 0 °� a �o °DgnD �o 0 LEVEL OUTLET 0 a ° Q b q c 4 4" PERF PIPE D o D A o Q n Q° zi 18' MIN A o0 0 fl n O 1 /2" -1" WASHED ROCK v a oQa ° O °n ) b of P 7 O Q Q R h 2C MIN TRENCH X-SECTION SLOPE -s 25' MIN TO PROPERTY LINE (VEGETATED) 10' L ICHES ALL CATCH BASIN PLAN VIEW OF ROOF NOTE: NOT TO SCALE 4.5.6-3 11194 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL Note 2: Where dispersion trenches are used and there is at least 25 feet of vegetated surface between the outfell and the property line, 50% of the impervious roof area may be modeled as grassed pervious area when calculating required RID size. Dispersion Trench System Design Downspout dispersion systems should be broken up to require a separate segment for each 700 square feet of roof, with no segments directly uphill from other segments. Discharge points are not to be located within 10 feet of property lines, adjacent to steep slopes, or in a manner which would cause flooding or erosion problems on downstream properties, or flow over septic systems. All discharges must be directed into vegetated areas. Each trench segment should include a small catch basin (plastic is acceptable) for sediment. removal and overflow. There should be 10 feet of trench per segment. The trenches should be level, 2 feet wide, 18 inches deep, filled with drain rock to the surface and have a 4 inch perforated pipe laid with 6 inches of rock cover (see Figure 4.5.6At. Perforated Stub -Out Design The perforated stub -out connection shall be placed between the downspouts and the stub -out to the storm drain. The location of the perforated connection should be selected to allow a maximum amount of runoff to infiltrate into the ground (ideally a dry location on the site that is relatively well - drained). Perforated stub -out connections shall consist of at least 10 feet of perforated pipe laid in a level 2 foot wide trench backfilled with washed drain rock. The drain rock shall extend to a depth of at least 8 inches below the bottom of the pipe and shall cover the pipe. The pipe shall be laid level and the rock trench shall be covered with filter fabric and 6 inches of random fill (see Figure 4.5.68). j 4.5.6-2 11194