The URL can be used to link to this page

17019 73RD PL W.PDFIIIIIIIIIIII 5821 17019 73RD PL W ADDRESS: /70l ( — .7314 &- /,fj TAX ACCOUNT/PARCEL NUMBER: E D �1-- 4& �/5 BUILDING PERMIT (NEW STRUCTURE): lye ——/95-3 I COVENANTS (RECORDED) FOR: CRITICAL AREAS: DETERMINATION: ❑ Conditional Waiver ❑ Study Required ❑ Waiver DISCRETIONARY PERMIT #'S: DRAINAGE PLAN DATED: PARKING AGREEMENTS DATED: EASEMENT(S) RECORDED FOR: PLANNING DATA CHECKLIST DATED: SCALED PLOT PLAN DA SEWER LID FEE $: SHORT PLAT SIDE SEWER AS BUILT DATED: SIDE SEWER PERMIT(S) #: V 77 I U GEOTECH REPORT DATED: STREET USE / ENCROACHMENT PERMIT #: WATER METER TAP CARD DATED: OTHER: LID #: 64 LATEMP\DSTs\Fonns\Street File Checklist.doc _ ra�.vc�..t tcc.vlc,W C;t17,7�;tU1J1'' ,,��yy P`KQJECT NAME: I PROJECT ADDRESS: ��IQ � Yj APPLICATION RECEIPT DATE: -7 /r ,1' , 7,^, ., r i�v a++ Reviewed by: (initial/date) PLANNING WPR/SWR STREET ENC�TRNG BUILDING FIRE SINGE FAMILY/K;LTIPIAL - "(Circle One) S VARI (S -Planning VARIANCE/SETFiACK E/SETRA ADJ. 1.-- CONDITIONAL USE. PERMIT ////// `'"--' ///////// // 77777 ADB REQUIRET'IQ�'I5 CHECKED OTHER ZONING REQUIREMENTS ////// "" ///////// //////// 4 K V� � rF t 11111117- ENVIRCX`A MAL FEATURES ////// ///////// //////// / ACCESS SLOPE &VEHICLE ACCESS ////•-///// /////// 6 "DRAINAGE /lQ 777771111 PLAN (On Site) ////// ///////// ///////// //////// 7 / 11111T/ // / 7777777 STREET FILE ' 777777777777777 LEGAL DESCRIPTION VERIFICATION ////// ///////// ///////// //////// 9 CIAIM/DEDICATIONS / // / ////// QUIT '10 17 EASEMW - PUBLIC/PRIVATE �tCALCLJLATE SBM CONNECTION�IF NO LID# ////// ///////// ///////// //////// 12 ,< 777777 77777777777T77777 PLAT/SUBDIVISICN REQUIREMENTS 13 MIGHT-0E-WAY 'CONSTRUCTION PERMIT REC_1D '�f ////// ///////// ///////// d ? " 14 �AOND REQp FOR PUBLIC IMPROVEMENTS + ''' ////// ///////// ///////// //////// 15 SOILS.CCNDITIONS;& GROUND ^; -' WATER'FIEM CHECKED -,i ////1/ ///////// ///////// //////// '" °'' 16 �'(STR_EET"PAVING REQUIRED' /�//�/// ///////// ///////// 17 LS ix ry' 1I / / / CURB AND GAI'TER REQUIRED <.SIDEWAIiC,,RDXIRED" ` '� i I — 19 #� // CURS CUT'MR DRIVEWAY RDQD ' `' ////// ///////// ///////// ////////// 20 111111777711111111 7777777777 — STREET NAME SIGN'REQD ///////// ///////// ////////// 21 111171 711111111 — OTfiER SIGNING READ/]/f/// 22 4 ^ - `SIDE SEWER AVAILAAILTTY / 11111I / / / / 23 A.> iTTT i1TfTi TTi'Ti777 -" EXISTING WATER MAIN SIZE ////// ///////// �FP, r //////// ////////// 24 �' WATER METER SIZE//�/ ///////// //////// ////////// 25. 'SERVICE^LINE SIZE ////// //////////"/ //////// 26 HYDRANT REQUIRID ,, ///////// ///////// //////// ////////// 27 / HYDRANT SIZE_EXISTING _ ////// ///////// //////// ////////// 28 TIT117TIT-/ /TIT CROSS CONNECTION INSPECTION READ ////// ///////// //////// ////////// 29 MTER METER CHARGE REQD ////// ///// ///////// p �� IT/1/ //////// 7777777777 ////////// 30 , / / — '' FIRE LINE CHARGE READ - SPRINKLER ///////// //////// ////////// 31 STREET CUT ////// ///////// ////////// 32 OPEN DITCH EXISTING ////// ///////// ///////// 33 CITY OF EDMONDS ��j'�P�`�;�' �p� �. AST INFORMATION SHEET • L� NEWro2, -EDONDS ��-u � ASSET NO. ❑ ADDITION NO-- 5'3 ��AlITION, TO ASSET NO. ❑ RETIREMENT DESCRIPTION SERIAL NO. LOCATION D / L� DEP . NO. ' " PURCHASE ORDER NO. PURCHASE ORDER DATE COST ' PROJECT NUMBER Zf/i ? //a If PROJECT COMPLETION DATE �� G COST �� D B.A.R.S. ACCOUNT NO. ESTIMATED LIFE o� INITIATED BY DATE APPROVED BY "SUBMIT ASSET INFORMATION SHEET WITH FINAL PAYMENT REQUEST 'SUBMIT ASSET INFORMATION SHEET UPON CLOSE OF PROJECT ACCOUNTING ONLY Er/DEPRECIATE MONTHLY DEPRECIATION AMOUNT ANNUAL DEPRECIATION AMOUNT G.L. ENTRY REFERENCE b P INITIAL DATE VERIFIED BY PROCESSED BATCH NO. DEPARTMENT FILE PLANNING DATA SINGLE FAMILY RESIDENTIAL STREET FILE Name: �,Av, Date: 10 23/o Site Address: �o _ %3 = p W Plan Check #: Zoa 1 14 0 Project Description: 2 - sa.•y aaa a/- 94 % j (ate[ r lGvt� LyPtwt,tK l 6ko rfC. rb< L/c ' �Cp bc.l� b 0-V j,rs., Sbr 7 5 4 Reduced Site Plan Provided: (YES / NO) /1 ,• Zoning: (Lp, j9 Z. Map Page: .45-7 Corner Lot: (YES / O) Flag Lot: (YES /N Critical Areas Determination #: ❑ Study Required 5+w01) C- jw 1,-/ '1441I'A TO-11 )? /&2.t, ❑ Waiver u944%1W wi 5i' pV SEPA Determination: L 5 DD LYdS 9 rQ di "9 ® Exempt ❑ Needed (for 500 cubic yards of grading or site within 200 feet of Puget Sound or Lake Ballinger) ❑ Fee ❑ Checklist ❑ APO List with notarized form Required Setbacks Street: O Side: D Side: —J-Rear: u Actual Setbacks Street: 0 Side: G Side: v Rear: 0 ❑ Detached Structures: �Jp,c . � � 4 ❑ Rockeries: No c S ,,,,,,,� parc+ ❑ Fences/Trellises: z. ❑ Bay Windows/Projecting Modulation: +.tea wz-u, 14,,, t Stairs Deck: Nw aQcK ud nes,r ja6 Buildin Height Datum Point: DAB Datum Elevation: Maximum Height Allowed: Z5. Actual Height: N 35z. Al v Other Parking Required: Z Parking Provided: 3 Lot Area: a55 x Sa : Z 7Sa fti)-- -77&7, Maximum Lot Coverage: 35°!!a Proposed: Lot Coverage Calculations: j L &� f 55 L : 224o L -75. ADU Created: (YES / la) a„� Subdivision: L, .. 15 Eh,,, v,Y-j Dv, I.- Cf4), nNsr 0„U, L Legal Nonconforming Land Use Determination Issued: (YES Comments 6 � 3�iZ•�5 1314. Sfs Plan Review By:Planning Data Form 04-11-06.doc Imf Yla (.ol�+'q 2/ I /off -Fvr Yn�g 92 _ I" 100.0' --1 141- , ��- - - - - - - - - NEW ADD ❑ EXISTING RESIDENCE 100.0' )LL 1 Sq.Ft. 1 Sq.Ft. 3 Sq.Ft. i Sq.Ft. 8 Sq.Ft. L-D 95 875' j 96 98 i 55'1 o° 100 [Z - - - - - - - - - - - - - 30'-0° I_�---2 0- 0 - - - -) - B 100.0' EXISTING DRIVEWAY 0 / 10 HEIGHT CALCS. A = 100.0' B = 100.0' C = 100.0' D = 95.875' TOTAL = 395.875' _ 4 = MAXIMUM: 98.97' + 25 ACTUAL: 123'-71" -FIRE HYDRANT / DATUM POINT - BASE +100' I EAGL I- BUILD: PARC O L Z LOT 30 006 6:44:07 AM, \' 9800 4 Proposed Upper Level Cantilever 0 Existing deck to be removed N HA-1 HA-2 Approximate top of slope HA eck B-2 � BI Proposed Two - Level Addition Existing 2-ft. high rockery Existing —' wall to be removed Existing Two -Level Residence Existing Upper Level Deck 73rd Place W. LEGEND HA-1 Number and Approximate • �- Property Line + Location of Hand Auger 0 10 20 B-1 * Approximate Location — — Number and Approximate of Cross- Section t Location of Boring Scale: 1 inch =10 feet a Reference: Site Plan based on a plan dated May 16, 2006, titled "Existing Residence: David and Darlene Stem," prepared by LOT Design Group. Project Number NELsoN GEOTECHNICAL No. Date Revision By CK 743106 Stem Residence Addition NGA ASSOCIATE3� INC. 1 W,� o(gmid ACO EHK Site Plan GEOTECHNICAL ENGINEERS & GEOLOGISTS Figure 2 Wa"mmb,WA9WM =r.;ft qrM 76FZI68 G (436)4W1=1F 4W-W10 U' Z NELSON GEOTECHNICAL A ASSOCIATES, INC. GEOTECHNICAL ENGINEERS & GEOLOGISTS Main Office Engineering -Geology Branch 17311 — 135`" Avenue NE, A-500 112 Olds Station Road, Suite C Woodinville, WA 98072 Wenatchee, WA 98801 (425) 486-1669 • FAX (425) 481-2510 (509) 665-7696 (Phone/Fax) (425) 337-1669 Snohomish County pr 10P MEMORANDUM DATE: October 4, 2006 TO: Larry Throndsen - Architect CC: Mr. David Stern FROM: Khaled Shawish, PE Calvin McCaughan, EIT RE: Footing Drain Elimination Stern Residence Addition Edmonds, Washington NGA File No. 743106 El\/ 10 200 DEPARTMEN AL EDMONDS ST BEET FILE val OCT BUILDING CITY OF This memorandum summarizes our opinions regarding the elimination of footing drains around the planned addition to the Stern Residence located at 17019 - 73`d Place West in Edmonds, Washington. We have previously prepared a geotechnical report for the project that recommended the use of footing drains around the planned addition. You have informed us that due to site grades, footing drains would be impractical for the project. Also, you have informed us that the runoff from the roof downspouts around the addition would be directed to the stormwater system running beneath 73`d Place West. We understand that the addition will be underlain by a crawl space. Based on our understanding of the soils within the project area, it is our opinion that footing drains can be eliminated from the project plans. The on -site soils consist of sand and silty sand, and groundwater conditions were not encountered in our explorations. However, the recommendations discussed below should be incorporated into the plans. We recommend that the bottom of the crawl space be graded such that water is not allowed to pond in the crawl space. Ponding water could cause damp conditions to develop within the addition. We also A- MPmnranclnm 0 Footing Drain Elimination Stern Residence Addition October 4, 2006 NGA File No. 743106 Page 2 recommend that adequate ventilation slots be incorporated into the design of the stemwalls and that fill is not placed on the outside of the stem walls higher than the elevation of the addition floor. We should be retained to evaluate the exposed soils and grades at the base of the crawlspace excavation and provide additional recommendations for drainage, if necessary. We trust this memorandum should satisfy your needs at this time. Please contact us if you have any questions or comments regarding our findings and recommendations, or if we can be of further help. NELSON GEOTECHN/CAL ASSOCIATES, INC. f,, + - ' s- �, .,N, y r�s 1f; .. Yr.ik. .�iYo i�i'i}4a, :.rue -:il��•o .;�.w`;-,. i.., .�. CITY of EDMaIDS So#E SEWER PERMIT For Inspection Call 771-3202 RLE PERMIT Njo. 07776 Address of Construction: `� ��( -?3��L• W�-� t Property Legal Description (Include all easements): L n —\ Z S 6Li -S Nr=< Owner and/or Builder: ��at �N--��--� p cvN�F_S _ay.0 • ;r. Contractor & License No: a 00 0 r l N N •r a) W Singl:e Family Residence Multi -Family Commercial (No. of Units ) (No. of fixture Units ) Invasion into City Right -of -Way: No )4, Yes (If Yes, Right -of -Way Construction Permit required. Call One -Call -Center (1-800-424-5555) before any excavation.) Cross other Private Property: No i4, Yes (If Yes, easement required, attach legal description and county easement number.) PLEASE READ THE ITEMS LISTED ON THE BACK I certify that I have read and shall comply with the items listed on the back. Date Permit Fee: A,30, V� °Issued By: Trunk Charge: �o?s� P-P Date Issued: Assessment Fee: Receipt No.: v Partial Inspection: Comments Date Initial Final Inspection Approved: _a5=8% Date Initial Rejected: Reason Date Initial ** PERMIT MUST BE POSTED ON JOB SITE ** White Copy - File Green Copy -Inspector Buff Copy - Applicant Side Sewer Drawing The City of Edmonds EASEMENT NO . ............................................ NEW CONSTRUCTION REPAIRS ❑ LID NO - ------------------ -ASMT. NO................ OWNER ---- C)-Qt-- _`- .LO)....--- .TqF—---------- .S-hJci---------- CONTRACTOR --- �-'-'A4 - - -------------------------------- ----------•--•-••---------- PERMIT NO. Q......7 .. 11-•-� p� `"j 2 1 \ �, l JOB ADDRESS-.l.--1 .�....1----------- `-----o--•-- ` �+`l S .......... LEGAL DESCRIPTION: LOT NO. -A BLOCK NO. .. W IA•�� 0 C��S �O � � P� Rr 1 ✓a l e s l Q s ti 1 v}s------- ---------------------------------------------------------------------------------- NAMEOF ADDITION----------------------------------------------------------------------------------------------------------------------- NNWOOD LINE 2�i ��IpU.e 6o Luu., 4Ol& i / Approved: DATE .q.-:;� �-...... -7-------.. B �` 3.30 A f -sue 36_ 338 340_ Zone Corner Flag I --Set l` 0 _Rcc��_:�,-nd Actual Front 0 Sides S Rear c= Other �{ t z� ; z ri? o rib 6�Z 1XISTING NEW TOTAL 828 Sq.Ft. 688 Sq.Ft. _ Total Living Area __i (o50pf. 6AAGc2 605 Sq.Ft. 605 Sq.Ft. 162 Sq.Ft. ,he-C-A-, 286 Sq.Ft. 448 Sq.Ft. 240 Sq.Ft. 3 31 '31 � 3'1 T NEW I )� C_K_ ' I i I I EXISTING RESIDENCE ---------------; 30'-0' p �r"ED B`(P iVN G ZJ EXISTING DRIVEWAY raj_-20_ 0'—� 316- -318 -320 322 ENGI OV D AS OTO 3 2 --Co 326 328 ss'� 332 330 0�0 334 \336 �338 o?3�AF 340 A �s 40 RECEIVED ---JU" 7 2014 DEVELOPMENT SERVICE. Colimp BUILDING SITE PLAN EXISTING/PROPOS: �,PARCE NUMBER 007415 000 015 00 EAGLES NEST DIV,2 BLK 000 D-00 LOT 15 SCALE 1" = 20'-0" PLANNING DATA SINGLE FAMILY RESIDENTIAL 11 STREET FILE Name:' S �n (Z:D 00 '� y S-0190 m t no d) Date: 2 l Site Address: -I -%0 1 �( % 'eo Plan Check #: 960 ZO ` 06 2 Z Project Description: ►J �G� (a� -eDc� Reduced Site Plan Provided: S NO) Zoning: Map Page:—` Corner Lot: (YES / Flag Lot: (YES Critical Areas Determination #: 3�? . (�pd�{Gh rypJ/IS cot,, 4011 Study Required f(c��S t 2 (2.Od (g f ❑ Waiver / SEPA Determination: Exempt ❑ Needed (for over 500 cubic yards of grading) ❑ Fee ❑ Checklist '❑ APO List with nota "zpd form Required Setbacks Gi < (/_ Street: O 1V Side: O i S��: O Rear:C) ` ActualSetbacks Street: Side: O+ Side: to Rear: Ot ❑ Detached Structures: ❑ Rockeries: ❑ Fences/Trellises: ❑ Bay Windows/Projecting Modulation: ❑ Stairs/Deck: Bui/din Hei bt Datum Point: ---�",- Datum Elevation: Maximum Height Allowed: 2 S Actual Height: \ Z Other Parking Required: Parking Provided -- Lot Area: 2, `7 p S� Maximum Lot Coverage: /o Pro osed: Lot Coverage Calculations: dvse— cl (6 2-vl0 -1 300 S� Z z�� ADU Created: (YES / O Subdivision: Legal Nonconforming Land Use Determination Issued: (YES / :. Comments Plan Review By: 4-- Planning Data Form 04-11-06.doc` City of Edmonds Critical Area Notice of Decision Applicant: S�fv Property Owner: Critical Area File #: C2 �� 1 3 Permit Number: �L� ?� yc96 2- Site Location: 790 aa� Parcel Number: .0 (, .7 1-(( D v a c:)/ J oc)o Project Description: LC Gc. C 'r"� ❑ Conditional Waiver. No critical area report is required for the project described above. There will be no alteration of a Critical Area or its required buffer. 2. The proposal is an allowed activity pursuant to ECDC 23.40.2 0, 23.50.2 0, and/or 23.80.040. f /Von Cr,.o� 3. The proposal is exempt pursuant to ECDC 23.40.230. So C I �f ❑ Erosion Hazard. Project is within erosion hazard area. Applicant must prepare an erosion and �� 206 6 sediment control plan in compliance with ECDC 18.30. v— J'() ;K Critical Area Report Required: The proposed project is within a critical area and/or a critical a ea buffer and a critical area report is required. A critical area report has been submitted and evaluated for compliance with the following criteria pursuant to ECDC 23.40.160: 1. The proposal minimizes the impact on critical areas in accordance with ECDC 23.40,120, Mitigation sequencing; 2. The proposal does not pose an unreasonable threat to the public health, safety, or welfare on or off the development proposal site; 3. l The proposal. is consistent with the general purposes of this title and the public interest; 4. Any alterations permitted to the critical area are mitigated in accordance with ECDC 23.40.110, Mitigation requirements. 5. The proposal protects the critical area functions and values consistent with the best available science and results in no net loss of critical functions and values; and 6. / The proposal is consistent with other applicable regulations and standards. ❑ Unfavorable Critical Area Decision. The proposed project is not exempt or does not adequately mitigate its impacts on critical areas and/or does not comply with the criteria in ECDC.23.40.160 and the provisions of the City of Edmonds critical area regulations. See attached findings of noncompliance. Favorable Critical Area Decision. The proposed project as described above and as shown on the attached site plan meets or is exempt from the criteria in ECDC 23.40.160, Review Criteria, and complies with the applicable provisions of the City of Edmonds critical area regulations. Any subsequent changes to the proposal shall void this decision pending re -review of the proposal. ❑ Conditions. Critical Area specific condition(s) have been applied to the permit number referenced above. See referenced permit number for specific condition(s). Reviewer Signature % Z� / Date Appeals: Any decision to approve, condition, or deny a development proposal or other activity based on the requirements of critical area regulations may be appealed according to, and as part of, the appeal procedure, if any, for the permit or approval involved. Revised 12/16/2010 GEOTECHNICAL ENGINEERING LETTER STERN DECK 17019-73RD PLACE WEST EDMONDS, WASHINGTON PREPARED FOR MS. DARLENE STERN Recel1v o JUL 17 2014 CEVELOPMEIVT SE CpuN�R RVICES �NGNELSON GEOTECHNICAL A AssOCIATES, INC. GEOTECHNICAL ENGINEERS & GEOLOGISTS Main Office 17311 — 135" Ave NE, A-500 Woodinville, WA 98072 (425) 486-1669 - FAX (425) 481-25 10 July 2, 2014 Ms. Darlene Stern 17019 — T) Place West Edmonds, Washington 98026 Geotechnical Engineering Letter Stern Deck Edmonds, Washington NGA File No. 8800B 14 Dear Ms. Stern: Engineering -Geology Branch 5526 Industry Lane, H2 East Wenatchee, WA 98802 (509) 665-7696 • FAX (509) 665-7692 This letter documents our recommendations for your new deck project at your residence located at 17019 — 73`d Place West in Edmonds, Washington. INTRODUCTION Development plans consist of constructing a new deck on to the northeastern corner of your existing residence. We previously prepared a geotechnical report for a house addition that was planned. in 2006, but it is our understanding that the addition was not constructed. Our report was titled "Geotechnical Engineering Evaluation — Stern Residence Addition — Edmonds, Washington," dated July 12, 2006. In the report, we recommended that the addition be supported on drilled piers. The updated plans include supporting the new deck on pin piles. We have been requested to provide an updated letter that provides recommendations for pin pile installation. For our use in preparing this letter, we were provided with the following documents: • Sheets S1.1 and S2.1 of the plans titled "Stern Residence Deck Addition — 17019 73rd PL W — Edmonds, WA 98026," prepared by CG Engineering dated September 10, 2013. Geotechnical Engineering Letter Stern Deck Edmonds, Washington NGA File No. 8800B14 July 2, 2014 Page 2 • An undated plan titled "Stern Sketch — Rear Deck Proposal," showing the extents of the existing deck and the new deck. SCOPE The purpose of this study is to explore and characterize the site surface and subsurface conditions, and provide general recommendations regarding the settlement and proposed foundation and underpinning support. Specifically, our scope of services under this phase includes the -following: 1. Review our original geotechnical evaluation documents. 2. Visit the site to observe existing conditions. 3. Review the provided deck plans. 4. Prepare an updated addendum letter regarding the new plans. SITE CONDITIONS Surface Conditions We visited the site on Wednesday, June 18, 2014 to observe the current conditions at the site. The deck will be located along the top of a steep slope on the northeastern corner of the residence. The ground is relatively level in the area of the deck then slopes steeply down. We observed that the slope was covered with trees and underbrush. We did not observe stability issues such as recent landsliding or sloughing on the slope. CONSLUSIONS AND RECOMMENDATIONS General Based on our recent observations, it is our opinion that the plans to support the new deck on pin piles are feasible. In the original report, we recommended that the foundation lines for the addition that was planned at the time be supported on drilled piers. The plans for the deck indicate that ten, 2-inch diameter pin piles will be utilized to support the new deck. The pin piles will be driven to refusal using a hand operated 140-pound jackhammer. For 2-inch diameter pipe piles driven to refusal using a hand-held, 140-pound jackhammer, we recommend a design axial compression capacity of two tons for each pile. The refusal criterion for this pile and hammer size is defined as less than one inch of movement during 60 seconds of continuous NELSON. GEOTECHNICAL ASSOCIATES, INC. w Geotechnical Engineering Letter NGA File No. 8800B14 Stern Deck July•2, 2014. Edmonds, Washington Page 3 driving. We recommend using galvanized extra strong (Schedule 80) steel pipe. The piles should be driven to a minimum depth of 12 feet below the existing ground surface. Other recommendations found in the 2006 report should be followed with respect to slope protection and erosion control. The steep slope should not be disturbed or modified through the placement of fill or removal of existing vegetation. Runoff should be collected in permanent catch basins or yard drains, and the drains should be routed to a permanent discharge location. Under no circumstances should water be allowed to concentrate or flow over the steep slope. We recommend that all downspouts and drains associated with the residence be investigated and improved as needed to ensure functionality and that all runoff generated on this site is diverted away from the slope. USE OF THIS LETTER NGA has prepared this letter for Ms. Darlene Stern and her agents for use in the pin pile supports planned for the new deck on this site only. The scope of our work does not include services related to construction safety precautions and our recommendations are not intended to direct the contractors' methods, techniques, sequences, or procedures, except as specifically described in our letter for consideration in design. There are possible variations in subsurface conditions between the explorations and also with time. Our letter, conclusions, and interpretations. should not be construed as a warranty of subsurface conditions. A contingency for unanticipated conditions should be included in the budget and schedule. We will be on site to monitor the installation of the pin piles and evaluate pile refusal; to observe actual conditions encountered in the field with respect to anticipated conditions; to provide recommendations for design changes should the conditions differ from anticipated; and to evaluate whether construction activities comply with contract plans and specifications. 0 ••• NELSON GEOTECHNICAL ASSOCIATES, INC. > Geotechnical Engineering Letter Stern Deck Edmonds, Washington NGA File No. 880OB14 July 2, 2014 Page 4 We appreciate the opportunity to provide service to you on this project. If you have any questions or require further information, please call. Sincerely, NELSON GEOTECHNICAL ASSOCIATES, INC. Bala Dodoye-Alali Project Geologist EXP. July 28, 2014 Khaled M. Shawish, PE Principal Three Copies submitted cc: Greg Guillen — CG Engineering (via email) Steve Magee — Custom Builders Inc (via email) BD:KMS:c.la NELSON GEOTECHNICAL ASSOCIATES, INC. NELSON GEOTECFINICAL YtG ASSOCIATES, INC. N A GEOTECHNICAL ENGINEERS & GEOLOGISTS Main Office 17311 —135`h Avenue NE, A-500, Woodinville, WA 98072 (425) 486-1669 • FAX (425) 481-2510 (425) 337-1669 Snohomish County 1 I July 12, 2006 Mr. David Stern . c/o 1VIr:'Larry Throndsen 22630 - 881h Avenue West Edmonds, Washington 98026 Geotechnical Engineering Evaluation Stern Residence Addition 17019-73`d Place West Edmonds, Washington NGA File No: 743106 Dear Mr. Stem, Engineering -Geology Branch 112 Olds Station Road, Suite C Wenatchee, WA 98801 (509) 665-7696 (Phone/Fax) We are pleased to submit this report titled "Geotechnical Engineering Evaluation — Stern Residence Addition - Edmonds, Washington." This report summarizes the existing surface and subsurface conditions within the project site and, provides general recommendations for the proposed improvements. Our services were completed in general accordance with the proposal signed by you on June 6, 2006. The proposed improvements include removing an existing deck and constructing a new, two-story residential addition and a new second -story deck along the eastern side of the existing residence. The addition and deck will be constructed at least partially over sloping ground, utilizing an exaggerated crawl space for storage. We explored the site subsurface soil and groundwater conditions with two soil borings using a portable limited access drill rig. Our explorations indicated that the site is underlain by up to seven feet of loose undocumented fill, that is in turn underlain by dense native outwash soils. From a 'geotechnical. standpoint, we have concluded that the planned development is feasible. However, due to the close proximity of the improvements to the steep slope, we have recommended that the residential additionbe supported, at least partially, on drilled piers extending down into the slope to maintain a minimum effective foundation setback distance of 25 feet between the face of the slope and the bottom of the footings. This setback requirement should also be maintained for shallow spread footings. The new improvements should also be structurally tied to the existing residence for added stability. Specific recommendations for design and installation of the drilled piers are included in the attached report. We also recommend that the planned deck be entirely cantilevered off the residence to reduce impacts on the slope. General site grading and drainage recommendations have also been included in this report. Preliminary Geotechnical Engineering Evaluation . Stern Addition July 12, 2006 NGA File No. 743106 Summary - Page 2 It has been a pleasure to provide service to you on this project. Please contact us if you have any questions regarding this report or require further information. Sincerely, NELSON GEOTECHNICAL ASSOCIATES, INC. i Khaled M. Shawish, PE Principal Three Copies Submitted TABLE OF CONTENTS INTRODUCTION......................................................................................................................................1 SCOPE.........................................................................................................................................................1 SITECONDITIONS.................................................................................................................................. 2 SURFACECONDITIONS.............................................................................................................................. 2 SUBSURFACECONDITIONS........................................................................................................................ 2 HYDROLOGICCONDITIONS....................................................................................................................... 4 SENSITIVEAREA EVALUATION............................................................................................ ......... 4 SEISMIC HAZARD EROSIONHAZARD..................................................................................................................................... 4 LANDSLIDE HAZARD/SLOPE STABILITY................................................................................................... 5 CONCLUSIONS AND RECOMMENDATIONS ................................................................................... 5 GENERAL................................................................................................................................................... 5 SLOPEPROTECTION................................................................................................................................... 7 EROSIONCONTROL.....................................:............................................................................................. 7 STRUCTURESETBACKS.............................................................................................................................. 7 SITE PREPARATION AND GRADING........................................................................................................... 8 FOUNDATIONSUPPORT............................................................................................................................. 8 SITEDRAINAGE....................................................................................................................................... 10 USEOF THIS REPORT ..........................................................................................................................11 LIST OF FIGURES Figure 1 — Vicinity Map Figure 2 — Site Plan Figure 3 — Cross Section A -A' Figure 4 — Cross Section B-B' Figure 5 — Soil Classification Chart Figures 6 and 7 — Boring Logs Figure 8 — Hand Auger Logs Figure 9 — Effective Setback Detail NELSON GEOTECHNICAL ASSOCIATES, INC. Geotechnical Engineering Evaluation Stem Residence Addition Edmonds, Washington INTRODUCTION This report presents the results of our geotechnical engineering investigation and evaluation of the proposed improvements to the Stem. Residence, located at 17019 - 73`d Place West in Edmonds, Washington, as shown on the Vicinity Map in Figure 1. The purpose of this study is to explore and characterize the subsurface soil and groundwater conditions within the site and. provide recommendations for the proposed improvements. For our use in preparing this report, we have been provided a set of floor plans titled "Existing Residence — David and Darlene Stern," dated May 16, 2006, prepared by LOT Design Group. Project plans include a 12-foot by 50-foot, two-story residential addition and 7-foot by 30-foot second - story deck, both located along the eastern side of the existing residence. The residence is located along the top of a steep eastern facing slope, which has a vertical relief of about 55 feet. Based on floor plans provided by LOT Design Group, the addition would extend 12 feet east of the existing residence and be constructed at least partially over sloping ground, utilizing an exaggerated crawl space for. storage. Specific stormwater management and grading plans were not available at the time this report was prepared. SCOPE The purpose of this study is to explore and characterize the site surface and subsurface conditions, and provide general recommendations for site development. Specifically, our scope of services includes the following: 1. • Review available soils and geologic maps of the area. 2. Explore the subsurface soil and groundwater conditions within the site with two geotechnical borings to depths of approximately 20 feet using a portable drill rig. The drill rig was subcontracted by NGA. 3. Map the conditions on the site slope and evaluate slope stability. 4. Provide recommendations for an effective structure setback from the steep slope. 5. Provide general recommendations for site grading and earthwork. 6. Provide recommendations for foundation support of the addition, including deep foundations. NELSON GEOTECHNICAL ASSOCIATES, INC. Geotechnical Engineering Evaluation Stern Residence Addition July 12, 2006 NGA File No. 743106 Page 2 7. Provide recommendations for site drainage and erosion control. 8. Document the results of our explorations, findings, conclusions, and recommendations in a written geotechnical report. SITE CONDITIONS Surface Conditions The property is a rectangular -shaped parcel covering approximately 2,750 square feet. The site measures roughly 55 feet in the east -west direction and 50 feet in the north -south direction. This is a zero -lot -line parcel with the land surrounding the site • owned by the Homeowners'. Association. The proposed development area will be within the eastern portion of the site behind the existing residence. The property is bounded to the north and south by residential properties, to the west by 73`d Place West, and to the east by undeveloped steeply sloping ground. The proposed development portion of the property is currently occupied by a second -story deck, and partially covered with cedar shrubs and ivy. Several young alder trees are located at the top of the slope. It appears that at least a portion of the ground along the top of slope was previously modified/filled to create a backyard. The slope is vegetated with scattered young to mature deciduous and fir trees, blackberries and underbrush. We observed thick tree stumps, debris, and fallen trees on the slope, but we did not observe bowing of the coniferous trees on the slope. A trail, approximately three to four feet wide has been excavated across the upper third of the slope. The bottom of the slope terminates in a ravine, which dips at an approximate inclination of 10 degrees to the north. 1 East of the ravine, the slope continues steeply upwards. Bent conifer trees were observed on this west - facing slope. We measured the approximate inclination of the east -facing slope using a hand-held clinometer. The slope inclined at approximately 34 to 40 degrees (68 to 84 percent) and is shown as Cross-section A -A' in Figure 3. The top of the slope within the proposed development area dips moderately to the south, as shown in Cross-section B-B,' presented as Figure 4. We did not observe ponding surface water or seepage emitting from the slope during our June 15, 2006 site visit. Subsurface Conditions Geology: The PreliminM Surficial Geologic Map of the Edmonds East and Edmonds West Quadrangles, Snohomish and King Counties, Washington, by Mackie Smith (U.S.G.S., 1975) was referenced for the NELSON GEOTECHNICAL ASSOCIATES, INC. Geotechnical Engineering Evaluation Stern Residence Addition July 12, 2006 NGA File No. 743106 Page 3 geologic conditions at the site. The site is mapped. as Vashon Till (Qt) and Esperance Sand (Qe). The Vashon Till is described as a non -sorted mixture of clay, silt, sand, and gravel and the Esperance Sand is described as sand with gravel and trace silt. Our explorations generally encountered dense sand with varying amounts of silt at depth, consistent with the description of the Esperance Sand. Explorations: The subsurface conditions within the site were explored on June 15, 2006 by drilling two borings to 21.5 feet below the existing surface using a portable drill rig. The approximate locations of our explorations are shown on the Site Plan in Figure 2. . A geologist from NGA was present during the explorations, examined the soils and geologic conditions encountered, obtained samples of the different soil types, and maintained logs of the borings. The soils were visually classified in general accordance with the Unified Soil Classification System, presented in Figure 5. The logs of our explorations are attached to this report and are presented as Figures 6 and 7. We present a brief summary of the subsurface conditions in the following paragraphs. For a detailed description of the subsurface conditions, the boring logs should be reviewed. Both explorations encountered a surficial 4.5 to 7.0 foot thick layer of very loose to loose, brown and gray, silty fine to medium sand with varying amounts of organics and gravel. Plastic and woodchips were also encountered in these surficial soils which we interpreted as undocumented fill. Below the fill, both explorations encountered gray, fine to medium sand with varying amounts of silt, interbedded with gray, silty fine sand. This material graded from medium dense to very dense with depth and we interpreted it to be native outwash. Both borings were terminated at 21.5 feet in the outwash material. We excavated three hand augers on the slope. Hand Auger 1 encountered a surficial layer of topsoil which extended to approximately 0.5 feet below the existing ground surface. Below the topsoil, Hand Auger 1 encountered loose to medium dense, orange -brown, silty fine to medium sand, which we interpreted as native outwash. Hand Auger 1 was terminated at a depth of 4.0 feet below the existing .ground surface. Hand Auger 2 encountered a surficial layer of topsoil extending 0.5 feet below the ground surface. Below the topsoil, Hand Auger 2 encountered loose to medium dense, gray -brown, silty fine to medium sand with gravel and pieces of compact silty fine sand with gravel. We interpreted this material to be slope wash. Hand Auger 2 was terminated in the slope wash material at a depth of approximately 1.5 feet. Hand Auger 3, located near the top of the slope, encountered a surficial layer of NELSON GEOTECHNICAL ASSOCIATES, INC. Geotechnical Engineering Evaluation Stern Residence Addition July 12, 2006 NGA File No. 743106 Page 4 loose, gray, iron -oxide stained, silty fine sand with gravel. We interpreted this material to be fill. The fill extended to approximately 2.5 feet below the existing ground surface. Below the fill, Hand Auger 3 encountered a layer of medium dense, light brown, silty fine sand with trace gravel. We interpreted this material to be weathered native outwash. Hand Auger 3 was terminated in the weathered outwash at a depth of 3.0 feet. Hydrologic Conditions Groundwater was not encountered in our explorations; however, it is our opinion that there is potential for a perched groundwater condition to develop on this site. Perched water occurs when surface water infiltrates through less dense, more permeable soils and accumulates on top of underlying, less permeable soils. On this site, the more permeable soils would consist of loose fill and the clean native sandy materials. The less permeable materials would consist of the very dense sand with varying amounts of silt. Perched water does not represent a regional groundwater "table" within the upper soil horizons. Perched water tends to vary spatially and is dependent upon the amount of rainfall. We would expect the amount of perched water to decrease during drier times of the year and increase during wetter periods. SENSITIVE AREA EVALUATION Seismic Hazard Medium dense to very dense outwash soils were encountered underlying the site. Based on the 2003 International Building Code (IBC), the site conditions best fit the description for Site Class D. Hazards associated with seismic activity include liquefaction potential and amplification of ground motion by soft deposits. Liquefaction is caused by a rise in pore pressures in a loose, fine sand deposit beneath the groundwater table. The medium dense to very dense outwash material interpreted to underlie the site has a low potential for liquefaction or amplification of ground motion. Erosion Hazard The erosion hazard criteria used for determination of affected areas includes soil type, slope gradient, vegetation cover, and groundwater conditions. The erosion sensitivity is related to vegetative cover and the specific surface soil types, which are related to the underlying geologic soil units. The Soil Survey, Snohomish County Area, Washington, by the Soil Conservation Service (SCS) was reviewed to determine the erosion hazard of the on -site soils. The site surface soils were classified using the SCS classification system as Alderwood-Everett gravelly sandy loam, 25 to 70 percent slopes. This unit is NELSON GEOTECHNICAL ASSOCIATES, INC. Geotechnical Engineering Evaluation Stern Residence Addition July 12, 2006 NGA File No. 743106 Page 5 listed as having a high erosion hazard for exposed soils. We consider the on -site soils on the steep slope to have a moderate erosion hazard in their current state with a vegetative cover. However, the erosion hazard on the steep slope would be severe if the vegetation were removed, or if stormwater runoff were allowed to concentrate and flow over the slope. Landslide Hazard/Slope Stability The criteria used for evaluation of landslide hazards include soil type, slope gradient, and groundwater conditions. A steep eastern -facing slope with inclinations ranging from 34 to 40 degrees (68 to 84. percent) is located in the area of the planned improvements. This slope has a vertical relief of approximately 55 feet. Significant erosion on the slope was not observed, but our explorations encountered loose fill on the top of slope and slopewash partway down the slope above a walking trail. We did not observe groundwater seepage emitting from the slope during our site visit. The core of the site slope is inferred to consist primarily of medium dense to very dense sand. Inclinations of up to 40 degrees on the slope indicate high strength and internal friction angle within the underlying unweathered soils. It is our opinion that there is not a significant potential for deep-seated slope.failuces within the native materials under current site conditions. Failures and erosion should be expected on the steep slope, especially within the undocumented fill if conditions are not improved. This potential could be limited through the maintenance of the vegetation on the steep slope and appropriate drainage systems. Proper site grading and drainage as well as vegetation management as recommended in this report should help improve stability conditions. It would be best to improve the density of the fill found on the slope to reduce sliding potential. We could consult with the designer and/or contractor regarding this at the time of construction. CONCLUSIONS AND RECOMMENDATIONS General It is our opinion from a geotechnical standpoint that the site is compatible with the proposed development. Our explorations indicate that a layer of loose fill underlies the area of the planned addition, with competent native soil deposits at depth. The planned residential addition and deck are to be constructed at least partially over sloping ground, in direct proximity to the steep slope. We consider this slope to be stable with respect to deep-seated failures, but shallow failures on the slope, especially in the undocumented fill are possible. NELSON GEOTECHNICAL ASSOCIATES, INC. Geotechnical Engineering Evaluation Stern Residence Addition July 12, 2006 NGA File No. 743106 Page 6 To protect the proposed development against potential failures on the slope, we recommend that the eastern and southern .foundation footing lines be supported on drilled piers. The piers should extend at least three feet into the competent native soils, and, extend deep enough to provide a horizontal effective setback distance of 25 feet between the bottom of the piers and the face of the slope, as indicated by the detail in Figure 9. A minimum pier length of 12 feet should be used for axial capacity considerations. The piers should consist of a minimum of 16-inch diameter cast -in place reinforced concrete. Recommendations for design and installation of the piers are presented in the Drilled Piers subsection of this report. The northern footing line of the addition could likely be constructed using shallow foundations; however, the footings should extend at least three feet into competent medium dense native soil, and the 25-foot effective setback criteria should still be achieved. Drilled piers could be used in lieu of the northern spread footing line. ,Specific recommendations for shallow foundations are discussed further in the Foundations subsection of this report. In addition to maintaining the recommended setback distance, the addition should be structurally tied to the existing residence for added stability. We recommend that the planned deck be cantilevered off the residence. This would eliminate the need for deep deck footing excavations through the undocumented fill. Deck supports, if utilized, should consist of 2-inch pin piles advanced through the fill down into the native material. Pin piles should consist of schedule 80 water pipe driven using a 140-lb jackhammer. Minimum pin pile embedments of 12 feet should be achieved. Also, the piles should be driven until an advancement rate of less than one inch per minute is reached. Excavation spoils should not be stockpiled near the slope. For this site, this area would include the entire backyard. It is prudent that the contractor develop a plan for the immediate removal of the drilled cuttings from the slope during construction, and a way of catching excavated debris before heading downslope. Runoff generated within the site should be collected and routed into a permanent discharge system and not be allowed to flow over the slope. Future vegetation management on the slope should be the subject of a specific evaluation and a plan approved by the City of Edmonds. Lawn clippings and any other debris should not be cast over the slope. NELSON GEOTECHNICAL ASSOCIATES, INC. Geotechnical Engineering Evaluation Stem Residence Addition July 12, 2006 NGA File No. 743106 Page 7 To improve the stability of the top of the slope area, it would be best to remove the existing fill and replace the fill with competent material. However, this may prove difficult. In this case, the fill face should be compacted using a heavy hoepack and then covered with erosion control material. The fill should be monitored, especially during the winter for any signs of movement or distress. Depending on fill performance, emergency repairs might need to be employed should fill movement be experienced. It is therefore our opinion that the planned deck should be entirely cantilevered off the residence and not be supported on pads near the fill. Future fill movement should not impact the addition if the addition is supported on deep foundations, however, future fill movement could impact any deck supports, even if pin piles are used. Slope Protection Protection of the steep slope should be performed as required by the City of Edmonds. Specifically, we recommend that the slope not be disturbed or modified through placement of any fill or removal of the existing vegetation. Any excavation spoils that reach the slope should be removed. Runoff should be collected in permanent catch basins or yard drains and should be routed into a permanent discharge system. Under no .circumstances should water be allowed to concentrate or flow over the slopes. Treating the existing fill as described above should help reduce the potential for future slope movement. Erosion Control The on -site soils can have moderate to severe erosion potential, depending on how the site is graded and how water is allowed to concentrate. Best Management Practices (BMPs) should be used to control erosion.. Areas disturbed during construction should be protected from erosion. Measures taken may include diverting surface water away from the stripped areas. Silt fences or straw bales should be erected to prevent muddy water from flowing over the site slopes or into the existing storm system. Disturbed areas should be replanted with vegetation at the end of construction. The vegetation should be maintained until established. Final grading should incorporate appropriate erosion control measures to route stormwater runoff away from the top of slope and into appropriate discharge locations. Structure Setbacks Uncertainties related to building along the top of steep slopes are typically addressed by the use of building setbacks. The purpose of the setback is to establish a "buffer zone" between the structure and the top of the slope so that ample room is allowed for normal slope recession during a reasonable life span NELSON GEOTECHNICAL ASSOCIATES, INC. Geotechnical Engineering Evaluation Stern Residence Addition July 12, 2006 NGA File No. 743106 Page 8 of the structure. In a general sense, the greater the setback, the lower the risk of slope failures to impact the structure. From a geological standpoint, the setback dimension is based on the slope's physical characteristics, such as slope height, slope gradient, soil type, and groundwater conditions. Other factors such as historical slope activity, rate of regression, and the type and desired life span of the development are important considerations as well. Based upon the conditions described above, it is our opinion that the potential for shallow sloughing -type failures exists on the steep slope. The planned addition will be set back approximately 15 feet from the top of the slope along the northern end of the site, and constructed over the top of slope to the east. To reduce the risk of potential slope failures of affecting the structure, the structure should be supported on foundations extending deep enough to provide a 25-foot effective setback from the face of the slope to the bottom of the footings. This will likely mean that the southern and eastern footing lines will have to be placed on drilled piers to maintain this requirement. Site Preparation and Grading Site preparation should consist of the removal of the existing deck and landscaping features, then stripping any topsoil or organic fill from the development area. The stripped material should be hauled off site. The stripped material should not be stockpiled near the slope or be used for structural fill. With granular soils exposed at the ground surface, the site should be prepared for access for the drill rig. This may include importing rock spalls or crushed rock to temporarily grade the- site so that the drilling equipment has access to the southern portion of the site. Also, initial access for the drilling equipment will likely be via the northern side yard. The contractor installing the drilled piers should be consulted regarding necessary site preparation for equipment access. Foundation Support Drilled Piers: We recommend that the eastern and southern foundation footing lines be supported on 16- inch reinforced concrete piers, extending a minimum of three feet into the medium dense or better native soils, while satisfying the recommended 25-foot effective setback from the face of the slope. Also, drilled piers should extend a minimum of 12 feet below the ground surface to develop sufficient axial capacity. The remainder of the foundations could be constructed using shallow spread footings extending at least three feet into the competent native soil. NELSON GEOTECHNICAL ASSOCIATES, INC Geotechnical Engineering Evaluation Stern Residence Addition July 12, 2006 NGA File No. 743106 Page 9 Based on the loose fill encountered in our explorations, an open hole drilling method will most likely be unfeasible. Caving conditions should be anticipated, and pile casing will likely be required. The holes should be cleaned of any slough or water prior to pouring concrete. We recommend that the concrete be readily available on site at the time of drilling. The holes should not be left open for any extended period of time, as sloughing debris and/or groundwater seepage into the excavations may hamper pier installation. For a 12-foot deep drilled pier installed successfully as described above, we recommend using design axial compression capacities of 14 tons for 16-inch piers. We should be consulted if higher capacities are needed. Lateral resistance on the piers could be calculated based on an equivalent fluid density of 150 pounds per cubic foot (pcf) applied to two pile diameters. The upper four feet should be neglected for the purpose of calculating the lateral resistance due to the existence of loose fill. A qualified structural engineer licensed in the State of Washington should design the piers. We should be retained to review the design. Shallow Foundations: For the portion of the addition supported on shallow spread footings, footings should extend at least three feet into the native medium dense or better soils.. Minimum foundation widths of 16 and 24 inches should be used for continuous and isolated spread footings, respectively, but footings should also be sized based on anticipated loads and allowable soil bearing pressure. Standing water should not be allowed to accumulate in footing trenches. All loose or disturbed soil should be removed from the foundation excavation prior to placing concrete. For foundations constructed as outlined above, we recommend an allowable design bearing pressure of not more than 2,000 pounds per square foot (psf) be used for the footing design for footings founded on the medium dense or better native soils. A representative of NGA should evaluate the foundation bearing soil prior to placing footing forms. We should be consulted if higher bearing pressures are needed. Current Uniform Building Code (UBC) guidelines should be used when considering increased allowable bearing pressure for short-term transitory wind or seismic loads. Potential foundation settlement using the recommended allowable bearing pressure is estimated to be less than one inch total and 1/2 inch differential between adjacent footings or across a distance of about 30 feet, based on our experience with similar projects. NELSON GEOTECHNICAL ASSOCIATES, INC. Geotechnical Engineering Evaluation Stern Residence Addition July 12, 2006 NGA File No. 743106 Page 10 Lateral loads may be resisted by friction on the base of the footing and passive resistance against the subsurface portions of the foundation. A coefficient of friction of 0.35 may be used to calculate the base friction and should be applied to the vertical dead load only. Passive resistance may be calculated as a triangular equivalent fluid pressure distribution. An equivalent fluid density of 150 pcf should be used for passive resistance design for a level ground surface adjacent to the footing. This level surface should extend a distance equal to at least three times the footing depth. These recommended values incorporate safety factors of 1.5 and 2.0 applied to the estimated ultimate values for frictional and passive resistance, respectively. To achieve this value of passive resistance, the foundations should be poured "neat' against the native medium dense soils or compacted fill should be used as backfill against the front of the footing. We recommend that the upper one foot of soil be neglected when calculating the passive resistance. Frictional resistance should be neglected for footings supported on drilled piers. Site Drainage Surface Drainage: Final site grades should allow for drainage away from the top of the steep slope and the residence. We suggest that the finished ground be sloped at a gradient of three -percent minimum for a distance of at least 10 feet away from slope and the addition. Runoff generated on this site should be collected and routed into a permanent discharge system or to the bottom of the slope. Under no circumstances should water be allowed to flow uncontrolled over the slope. Subsurface Drainage: If groundwater is encountered during construction, we recommend that the contractor slope the construction area and collect the water into ditches and small sump pits where the water can be pumped out and routed into a permanent storm drain. We recommend the use of footing drains around structures. Footing drains should be installed at least one foot below planned finished floor elevation. The drains should consist of a minimum four -inch -diameter, rigid, slotted or perforated, PVC pipe surrounded by free -draining material wrapped in a filter fabric. We recommend that the free - draining material consist of an 18-inch-wide zone of clean (less than three -percent fines), granular material placed along the back of walls. Pea gravel is an acceptable drain material or drainage composite may also be used instead. The free -draining material should extend up the wall to one foot below the finished surface. The top foot of soil should consist of impermeable soil placed over plastic sheeting or building paper to minimize surface water or fines migration into the footing drain. Footing drains should discharge into tightlines leading to an appropriate collection and discharge point with convenient cleanouts to prolong the useful life of the drains. Roof drains should not be connected to footing drains. NELSON GEOTECHNICAL ASSOCIATES, INC. Geotechnical Engineering Evaluation Stern Residence Addition July 12, 2006 NGA File No. 743106 Page 11 USE OF THIS REPORT NGA has prepared this report for Mr. David Stern and his agents for use in the planning and design of the development planned on this site only. The scope of our work does not include services related to construction safety precautions and our recommendations are not intended to direct the contractors' methods, techniques, sequences, or procedures, except as specifically described in our report for consideration in design. There are possible variations in subsurface conditions between the explorations and also with time. Our report, conclusions, and interpretations should not be construed as a warranty of subsurface conditions. A contingency for unanticipated conditions should be included in the budget and schedule. We recommend that NGA be retained to review final project plans and provide consultation regarding structure placement, drilled pier capacities, setback distances, and foundation support. We also recommend that NGA be retained to'provide monitoring and consultation services during construction to confirm that the conditions encountered are consistent with those indicated by the explorations, to provide recommendations for design changes should the conditions revealed during the work differ from those anticipated, and to evaluate whether or not earthwork and foundation installation activities comply with contract plans and specifications. We should be contacted a minimum of one week prior to construction activities and could attend pre -construction meetings if requested. All people who own or occupy homes on hillsides should realize that landslide movements are always a possibility. The landowner should periodically inspect the slope, especially after a winter storm.. If distress is evident, a geotechnical engineer should be contacted for advice on remedial/preventative measures. The probability that landsliding will occur is substantially reduced by the proper maintenance r of drainage control measures at the site (the runoff from the roofs should be led to an approved discharge point). Therefore, the homeowner should take responsibility for performing such maintenance. Consequently, we recommend that a copy of our report be provided to any future homeowners of the property if the home is sold. Within the limitations of scope, schedule, and budget, our services have been performed in accordance with generally accepted geotechnical engineering practices in effect in this area at the time this report was prepared. No other warranty, expressed or implied, is made. Our observations, findings, and opinions are a means to identify and reduce the inherent risks to the owner. NELSON GEOTECHNICAL ASSOCIATES, INC. Geotechnical Engineering Evaluation Stern Residence. Addition July 12, 2006 NGA File No. 743106 Page 12 It has been a pleasure .to provide service to you on this project. If you have any questions or require further information, please call. Sincerely, NELSON GEOTECHNICAL ASSOCIATES, INC. Calvin. A. McCaughan, EIT Senior Staff Engineer %�42-o(p Khaled M. Shawish, PE Principal CAM:KMS:lam Nine Figures Attached NELSON GEOTECHNICAL ASSOCIATES, INC. VICINITY MAP Not to Scale oi�9y� . t 6Oth St Sw Wdale 4 .... Pt sw �,' 160ih `1 al. PI Sws I ' d PI Sw_ _ 164tIII StSv+ M.. t r eaa 3 a ,t; _ J Pro ect';: y �? 1. ` ;- '•-�.+� .1 � Site d✓ ��i�r: 170th Pi Sw {ed, T.el ` 173rd St Sw" 1G PL jr Cyrus PI _j 4 t I. j galhot Rd -- St Stv �t 7. 174th St Sw .. G Fiedenck t?I t 17_ Sth,_ —141 .11 ,I . . t® 2606 MaDCuest; Inc; -` ot 177th Stw- Z.�� I� sm I iV i fa ;3 - -� 179th St Sw - St S IF l i a 1l SE Sw ... �! 1 EASY :Pt Sw. y T , 020066 NAVTEQ Edmonds, WA Project Number NIL soN GEOTECHNICAL No. Date Revision By CK " Stem Residence Addition AsSOCIATES� INC. 743106 N C� A 1 7110106 Original ACO EHK Vicinity Magi GEOTECHNiCAL ENGINEERS & GEOLOGISTS Figure 1 i1J,1-,]6E A .HE WmRwW, WA 98072 dW9w�09S (424W1WQ1iu481-3510 -T,E7e5i8 d ~.mlmnPal ch— LL' N • \ — HA-1 IN, — — HA-2 \ Approximate B-1 top of slope + HA Proposed Upper Level Cantilever I leck B-2 i I' I Existing deck to be removed Proposed Two - Level Addition Existing 2-ft. high rockery Existing — wall to be removed I Existing Two -Level Residence Existing Upper Level Deck 73rd Place W. LEGEND HA-1 I Number and Approximate • Property Line Location of Hand Auger 0 10 20 A AApproximate Location B-1 Number and Approximate of Cross- Section + Location of Boring Scale: 1 inch = 10 feet ' a rn Reference: Site Plan based on a plan dated May 16, 2006, titled "Existing Residence: David and Darlene Stem," prepared by LOT Design Group. o Project Number NELSON GEOTECHNICAL No. Date Revision By CK 743106 Stem Residence Addition NGA ASSOCIATES, INC. , sr27/06 Original ACO EHK W Site Plan GKOTECHNICAL ENGINIXIMS & GBOI.OGISTO Figure 2 173„-,11N Ah. NE A300 9nomnim cw ty i.26 ,-150 WmAnvb, WA 99W2 Ww•thWgrim 6W)76t-276D = 0 Q (425) 4E61W9 / Fa 4L1,2510 ww.ndo�po Z A A'' -4m oZ West l I c� 80 Proposed Proposed (n Addition Deck co 03 B-2 (Projected 10 ft. South) a Cn X Existing B-1 (Projected 10 ft. North) y (D Residence R Cl)i1 3 0 5 60 „•26 Fill ; O n y 44 e 12 a Dn ,.ID a--, o .� �e co ' 40 _ J W Medium dense to very n 0 Z Z, dense,ouiwash soils HA Slopewash o r z 20 m Yto r _ to z 0 o HA-1 m E� Ilk m a Ip -4 o It to M 0 10 � c zZ I I I I I I I I I I I I I I I 101 - 0 20 40 60 80 100 120 140 m 0 Distance (feet) - ; Exploration East 80 .a 40 20 '11 a Boring Designation B-1 23 SPT N-value NOTES: m m m <_ Groundwater Level —� 1) Stratigraphic conditions are interpolated between s During Exploration 23 the explorations. Actual conditions may vary. Geologic Contact � ? 23_ —? 2) Elevations are arbitrary. (approximate) o.c° x 1 A 1 Reference: Cross Section is based on field measurements using a hand-held clinometer and 100-ft tape measure. -4 A B BI C W Z _ O O C 3 1 - North HA-3 (Projected 8 n. West, I South C 40 40 a 3 R Existing Rockery N W CI , m 30 B-2 R 30 ca Q ao 3 3* n o :3 v C O zo r Medium dense to very : ""cts c a'� 20 den seroutwash sods 20 o Z y w s Z Q r z a 10 10 a w O to� 78 z � m aM §a !p M -1 - d G n a r S 0 _ r _ _. 0 Z F 0 50 10 20 30 40 Exploration �e = n ,c Reference: Cross Section is based on field measurements Boring Designation � B-1 za 23 E— SPT N-value Groundwater Level 23 During Exploration za Geologic Contact (approximate) Distance (feet) NOTES: 1) Stratigraphic conditions are interpolated between the explorations. Actual conditions may vary. 2) Elevations are arbitrary. a hand-held clinometer and 100-ft tape measure. ' UNIFIED SOIL CLASSIFICATION SYSTEM GROUP MAJOR DIVISIONS GROUP NAME SYMBOL CLEAN GW WELL -GRADED, FINE TO COARSE GRAVEL COARSE- GRAVEL GRAVEL GP POORLY -GRADED GRAVEL GRAINED MORE THAN 50 % GRAVEL GM SILTY GRAVEL OF COARSE FRACTION RETAINED ON SOILS NO.4 SIEVE WITH FINES GC CLAYEY GRAVEL SAND CLEAN, $W WELL -GRADED SAND, FINE TO COARSE SAND SAND SP POORLY GRADED SAND MORE THAN 50 % RETAINED MORE THAN 50 N0.200 SIEVE OF COARSE FRACTION SAND SM SILTY SAND PASSES NO.4 SIEVE SC WITH FINES CLAYEY SAND FINE - SILT AND CLAY ML SILT INORGANIC GRAINED LIQUID LIMIT CL CLAY LESS THAN 50 % SOILS ORGANIC OL ORGANIC SILT, ORGANIC CLAY SILT AND CLAY MH SILT OF. HIGH PLASTICITY, ELASTIC SILT INORGANIC MORE THAN 50 % PASSES LIQUID LIMIT CH CLAY OF HIGH PLASTICITY, FLAT CLAY NO.200 SIEVE 50 % OR MORE ORGANIC OH ORGANIC CLAY, ORGANIC SILT HIGHLY ORGANIC SOILS PT PEAT NOTES: 1) Field classification Is based on visual SOIL MOISTURE MODIFIERS: examination of soil In general accordance with ASTM D 2488-93. Dry - Absence of moisture; dusty, dry to the touch 2) Soil classification using laboratory tests Is based on ASTM D 2488-93. Moist - Damp, but no visible water. 3) Descriptions of soil density or Wet - Visible free water or saturated, consistency are based on usually soil is obtained from Interpretation of blowcount data, below water table visual appearance of soils, and/or test data. Project Number NELSON GEOTECHNICAL No. Date Revision By CK 743106 Stem Residence Addition Soil Classification Chart NGA ASSOCIATES, INC. GEOTECHNICAL ENGINEERS & GEOLOGISTS 1 8/29/06 Original Aco EHK Figure 5 17H11-166atAMM-,Ad00 6rofomYhCmry(�21 a67-16eo WoodhVW WA86072 Wm�Id�dCMen 784-2755 (426)168-18691A&X461.=0 wWw — BORING LOG B-1 Approximate Ground Surface Elevation: Soil Profile Sample Data Penetration Resistance (Blows/foot - 0) Co y Piezometer 10 20 30 140 50 50+ 12 Installation - `-' c L- Ground Water Description P L rn J a o M M B - 3 c C r '=- Moisture Content (Percent - g o Data (9 E, v� m' o a Q 10 20 30 40 50 50+ m (Depth in Feet) PL J Light brown, silty fine sand with organics and woodchips 5 (loose, moist) FILL -- ' -slightly iron -oxide stained, very loose ;'• ---' SM 3 a ---• 5 .................................................. 5 -with trace gravel — 6 Light brown, iron -oxide stained, silty fine to medium sand, SM 12 with trace gravel (medium dense, moist) — ., ---------------- Brown -gray, iron -oxide stained, fine to medium sand with silt and (medium dense, moist) -. : — SP-SM 14 10 •• 10 gravel Gray, silty fine to medium sand with gravel (dense, moist) �,,a... 43 " SP .. 15 .................................................. 15 Gray, fine to medium sand with silt and trace gravel (dense, moist) �• SP-SM 38 ------------- Gray, silty fine to medium sand with trace gravel . , — 20 ......•• ......••• ......•• ••••• •• ......•• ......• 20 (dense, moist) SM 37 Boring was terminated below existing grade at 21.5 feet on 6/15/06. Groundwater seepage was not encountered during drilling. 25 ................................................... 25 l/ LEGEND ❑ Solid PVC Pipe Concrete M Moisture Content ergsiz Limits Depth Driven and Amount Recovered. 0 Slotted PVC Pipe Bentonite A AtterGrainize Analysis with 2-inch O.D. Split -Spoon Sam ler Monument/ Cap 4y� G P li r .? Native Soil DS Direct Shear Direct to Piezometer PP Pocket Penetrometer Readings, tons/ft ® Depth Driven and Amount Recovered Q Silica Sand ; P �r Liquid Limit P Sample Pushed � with 3-inch Shelby Tube Sampler + Plastic Limit = Water Level T Triaxial NOTE: Subsurface conditions depicted represent our observations at the time and location of this exploratory hole, modified by engineering tests, analysis and judgement. They are not necessarily r representative of other times and locations. We cannot accept responsibility for the use or interpretation by others of information presented on this ft. Project Number _ NELSON GEOTECHNICAL No. Date Revision By i CK Ic 743106 Stem Residence Addition NC7AssoCIATEs, INC. Boring Log GEOTECHNICAL ENCdINEERs & GEOLOGIsra 17311.135Qh Avg. NE, A-SM emhomhh county ((/25)) 337-1669 WoodhAh, WA 99 M WauhhedChW (5�!)7M-2786 "25"0e-1669IFU 01-2510 1N,,a.oro.0 mm 1 mama oriahal ACO EHK q rl C Figure 6 Page 1 of 1 BORING LOG - B-2 , Approximate Ground Surface Elevation: Soil Profile Sample Data Penetration Resistance (Blows/foot - 0) Piezometer 10 20 30 40 50 50+ v, H Installation - �, c Ground Water Description o o, n .0 E E 3 E CL a c_ m Moisture Content (Percent - �) Data O O fn m ca 10 20 30 40 50 50+ (Depth in Feet) J Topsoil loose moist)3 Gray, silty fine to medium sand with organics, gravel, and ; '..... pieces of plastic (very loose to loose, moist) FILL ' T< SM �.. 4 a — — — — — — — — — — — — — — — Brown -gray, iron -oxide stained, silty fine to medium sand - — 5 ......•• .................. 5 with trace gravel (medium dense, moist) 20 ' sM -grades to dense •'. , 44 — — — — — — — — — — — — — — — Gray, fine to medium sand with trace silt and trace gravel 10 interbedded with gray, silty fine to medium sand 54 (very dense, moist) SP/SM 15 .................................................. 15 .:^ 76 Gray, fine sand with silt (very dense, moist) ..; • .. 78 Boring was terminated below existing grade at 21.5 feet on 6/15/06. Groundwater seepage was not encountered during drilling. 25 ................................................... 25 LEGEND ❑ Solid PVC Pipe Concrete M Moisture. Content Limits Depth Driven and Amount Recovered Slotted PVC Pipe Bentonite A AttGrain-rbergsize with 2-inch O.D. Split -Spoon Sam ler Monument/ Ca G Grain -size Analysis P P � � Native Soil DS Direct Shear to Piezometer PP Pocket Penetrometer Readings, tons/ft Depth Driven and Amount Recovered q Q Silica Sand ; P �c Liquid Limit P Sample Pushed � 3-inch Shelby with Tube Sampler + Plasfic Limit 1 Water Level 7 Triaxial NOTE: Subsurface conditions depicted represent our observations at the time and location of this exploratory hole, modified by engineering tests, analysis and judgement. They are not necessarily representative of other times and locations. We cannot accept responsibility for the use or interpretation by others of information presented on this log. i Project Number NELSON GEOTECHNICAL No. Date Revision By i CK 743106 Stem Residence Addition NGA ASSOCIATES, INC. f Boring Log GEOTECHNICAL ENGINEERS & GEOL(OGIsTs 1T 11IM d�•WAOaM WaslohslChYa (bW 25 7Md736 (4294WJ66s1F.,,4e1-z510 i 8l28108 Orighal ACO EFiK r Figure 7 Page 1 of 1 .�.� DEPTH (FEET) USC LOG OF EXPLORATION , SOIL DESCRIPTION HAND AUGER ONE 0.0-0.5 DARK BROWN, SILTY FINE SAND WITH ORGANICS AND ROOTS (LOOSE, MOIST) (TOPSOIL) 0.5-3.5 SM ORANGE -BROWN, SILTY FINE TO MEDIUM SAND WITH TRACE SAND, TRACE ORGANICS, AND TRACE ROOTS (LOOSE TO MEDIUM DENSE, MOIST) 3.5-4.0 SM GRAY -BROWN, IRON -OXIDE STAINED, SILTY FINE TO MEDIUM SAND WITH TRACE GRAVEL AND TRACE ORGANICS (MEDIUM DENSE, MOIST) SAMPLES WERE COLLECTED AT 2.0 AND 3.9 FEET GROUNDWATER SEEPAGE WAS NOT ENCOUNTERED HAND AUGER CAVING WAS NOT ENCOUNTERED. HAND AUGER WAS COMPLETED AT 4.0 FEET ON 6/15/06 HAND AUGER TWO 0.0-0.5 DARK BROWN, SILTY FINE SAND WITH ORGANICS AND ROOTS (LOOSE, MOIST) _ (TOPSOIL) 0.5 -1.5 SM GRAY -BROWN, SILTY FINE TO MEDIUM SAND WITH GRAVEL AND PIECES OF SILTY, FINE SAND WITH GRAVEL (LOOSE TO MEDIUM DENSE, MOIST) (SLOPE WASH) SAMPLE WAS COLLECTED AT 1.4 FEET GROUNDWATER SEEPAGE WAS NOT ENCOUNTERED HAND AUGER CAVING WAS NOT ENCOUNTERED HAND AUGER WAS COMPLETED AT 1.5 FEET ON 6/15/06 HAND AUGER THREE 0.0-0.2 DARK BROWN, SILTY FINE SAND WITH ORGANICS AND ROOTS (LOOSE, MOIST) (TOPSOIL) 0.2 -2.5 SM GRAY, IRON -OXIDE STAINED, SILTY FINE SAND WITH GRAVEL 4 (LOOSE TO MEDIUM DENSE, MOIST TO WET) (FILL) 2.5 -3.0 SM LIGHT BROWN, SILTY FINE SAND WITH TRACE GRAVEL (MEDIUM DENSE, MOIST) SAMPLES WERE COLLECTED AT 2.0 AND 2.9 FEET GROUNDWATER SEEPAGE WAS NOT ENCOUNTERED HAND AUGER CAVING WAS NOT ENCOUNTERED HAND AUGER WAS COMPLETED AT 3.0 FEET ON 6/15/06 EHK:ACO NELSON GEOTECHNICAL ASSOCIATES, INC. FILE NO 743106 FIGURE 8 Typical Foundation Effective Setback Detail Footing Deepen footing excavation achieve the recommended setback from face of slope, or use drilled piers with a minimum 12-foot depth to achieve setback. (Not To Scale) three feet below bottom of fill. Minimum 25-foot Horizontal distance from face of slope a o Project Number NELSON GEOTECHNICAL No. Date Revision By cK 743106 Stem Residence Addition N GA ASSOCIATES INC. , 7110/06 odginal ACO Cana Foundation Effective Setback GEOTECHNICAL ENGINEERS & GEOLOGISTS Figure 9 IM11.159BiA—W-A= Bnomn+.ncwnry (� �-tom o g Wao*,w..WAGWn W.�uM1�CIW.n (SOB ,6t-T,56 I42e14W1W91 ram. ref-za1B wv.wnrmro z ��,�'I�:�q'��;.� ``� r` .,,,;�,� '.� So o' _ • . , � ,l �' alb E7� � �'� �•!`� t l , F . s a . r ice: -- .� _:=` --�., � �- .� ' ; ' _ ' � • :: F ':. 04 PI 627 spa•{` ^ t _J{t' r ,� r% ' _ �;.'`...+' '"tc'sA�" _ •' 'r.'9'!- s� (Z-�! s7_?LArI. /fir^EtJDh�CJ?�'' �o c1I 16L � ' +� J//-•'��\ �' � }1'' //1��,/ �ry�w^�,�r��T.I 1, E-�� R•r�O�+� ,�.,�.:J.-'N-"6J E W I f��/, C o � ,.(*ir* ,�. `,d• d', '• Il 1 1. � � 9,'�' _�_ K._'.. _-•�. - J.. Y f �,)�' �^ ?��%'•. I. N �ti • ^.�.s^•^ -,f r � ... �,' ' r It-r &�� I' � —�`•?�t��•?F,�'�t-' ��►'i`?.�''��ZS�•.3D:•�''•�''�'7.10��- ,I:'�?1.?.�•�=r�r �',; � , f�, ; .� �°s.. / j', 'r�� I-//'1rr y ,`w k. Tl�✓`GFN +., "r' •�� "�,,• + - f ✓", i n";'ti r x.'t 19 1 . 000 .. ... � - - (.\''-'�. � � Q� � �•. �` y.UJV .,�'•-.a♦ :. �'' . .. ..... �y .'_Z .... s. - . � .. , :.... 1•.a v...ti�.�.:e..:�.:-� .. s4 GEOTECHNICAL ENGINEERING EVALUATION STERN- RESIDENCE ADDITION EDMONDS, WASHINGTON PREPARED FOR MR. DAVID STERN 'A l 170/9- 73/` vl/ STREET FILE RECEj�V® OCT 10 2006 BUILDING DEPARTM> NT CITY OF EDMONDS T I NGA ' Main Office - 17311 —13e Avenue NE, A-500 Woodinville, WA 98072 (425) 486-1669 • FAX (425) 481-2510 (425) 337-1669 Snohomish County NELSON GEOTECHNICAL ASSOCIATES, INC. GEOTECHNICAL ENGINEERS & GEOLOGISTS • CJuly2, 2006 Mr_David Stern . ' c/o Mr:'Larry-Throndsen 22630 - 88`h Avenue West Edmonds, Washington 98026 ' Geotechnical Engineering Evaluation Stern Residence Addition 17019-73'd Place West Edmonds, Washington NGA File No: 743106 I Dear Mr. Stern, Engineering -Geology Branch 112 Olds Station Road, Suite C Wenatchee, WA 98801 (509) 665-7696 (Phone/Fax) We are pleased to submit this report titled "Geotechnical Engineering Evaluation — Stem Residence ' Addition - Edmonds, Washington." This report summarizes the existing surface and subsurface conditions within the project site and. provides general recommendations for the proposed improvements. Our services were completed in general accordance with the proposal signed by you on June 6, 2006. ' The proposed improvements include removing an existing deck and constructing a new, two-story residential addition and a new second -story deck along the eastern side of the existing residence. The ' addition and deck will be constructed at least partially over sloping ground, utilizing an exaggerated crawl space for storage. We explored the site subsurface soil and groundwater conditions with two soil borings using a portable ' limited access drill rig. Our explorations indicated that the site is underlain by up to seven feet of loose undocumented fill, that is in turn underlain by dense native outwash soils. From a geotechnical standpoint, we have concluded that the planned development is feasible. However, due to the close proximity of the improvements to the steep slope, we have recommended that the residential additionbe supported, at least partially, on drilled piers extending down into the slope to ' maintain a minimum effective foundation setback distance of 25 feet between the face of the slope and the bottom of the footings. This setback requirement should also be maintained for shallow spread footings. The new improvements should also be structurally tied to the existing residence for added stability. Specific recommendations for design and installation of the drilled piers are included in the attached report. We also recommend that the planned deck be entirely cantilevered off the residence to reduce impacts on the slope. General site grading and drainage recommendations have also been included I in this report. Preliminary Geotechnical Engineering Evaluation Stern Addition July 12, 2006 NGA File No. 743106 Summary - Page 2 It has been a pleasure to provide service to you on this project. Please contact us if you have any questions regarding this report or require further information. Sincerely, NELSON GEOTECHNICAL ASSOCIATES, INC. Khaled M. Shawish, PE Principal Three Copies Submitted -. 1 TABLE OF CONTENTS INTRODUCTION......................................................................................................................................1 SCOPE.........................................................................................................................................................1 SITECONDITIONS.................................................................................................................................. 2 SURFACECONDITIONS.............................................................................................................................. 2 SUBSURFACECONDITIONS........................................................................................................................ 2 HYDROLOGICCONDITIONS....................................................................................................................... 4 SENSITIVEAREA EVALUATION......................................................................................................... 4 SEISMICHAZARD...................................................................................................................................... 4 EROSIONHAZARD..................................................................................................................................... 4 LANDSLIDE HAZARD/SLOPE STABILITY................................................................................................... 5 CONCLUSIONS AND RECOMMENDATIONS................................................................................... 5 GENERAL................................................................................................................................................... 5 SLOPEPROTECTION................................................................................................................................... 7 EROSIONCONTROL................................................................................................................................... 7 STRUCTURESETBACKS.....................................................................:....................................................... 7 SITEPREPARATION AND GRADING........................................................................................................... 8 FOUNDATIONSUPPORT ............................................................................ ................................................. 8 SITEDRAINAGE....................................................................................................................................... 10 USEOF THIS REPORT.......................................................................................................................... n LIST OF FIGURES Figure 1 — Vicinity Map Figure 2 — Site Plan Figure 3 — Cross Section A -A' Figure 4 — Cross Section B-B' Figure 5 — Soil Classification Chart Figures 6 and 7 — Boring Logs Figure 8 — Hand Auger Logs Figure 9 — Effective Setback Detail NELSON GEOTECHN/CAL ASSOCIATES, INC. Geotechnical Engineering Evaluation g g Stern Residence Addition Edmonds, Washington INTRODUCTION This report presents the results of our geotechnical engineering investigation and evaluation of the ' proposed improvements to the Stern Residence, located at 17019 - 73'd Place West in Edmonds, Washington, as shown on the Vicinity Map in Figure 1. The purpose of this study is to explore and ' characterize the subsurface soil and groundwater conditions within the site and provide recommendations for the proposed improvements. For our use in preparing this report, we have been provided a set of floor ' plans titled "Existing Residence — David and Darlene Stern," dated May 16, 2006, prepared by LOT Design Group. ' Project plans include a 12-foot by 50-foot, two-story residential addition and 7-foot by 30-foot second - story deck, both located along the eastern side of the existing residence. The residence is located along ' the top of a steep eastern facing slope, which has a vertical relief of about 55 feet. Based on floor plans provided by LOT Design Group, the addition would extend 12 feet east of the existing residence and be constructed at least partially over sloping ground, utilizing an exaggerated crawl space for storage. Specific stormwater management and grading plans were not available at the time this report was ' prepared. SCOPE The purpose of this study is to explore and characterize the site surface and subsurface conditions, and provide general recommendations for site development. Specifically, our scope of services includes the following: 1. Review available soils and geologic maps of the area. 2. Explore the subsurface soil and groundwater conditions within the site with two geotechnical borings to depths of approximately 20 feet using a portable drill rig. The drill rig was subcontracted by NGA. 3. Map the conditions on the site slope and evaluate slope stability. 4. Provide recommendations for an effective structure setback from the steep slope. 5. Provide general recommendations for site grading and earthwork. 6. Provide recommendations for foundation support of the addition, including deep foundations. NELSON GEOTECHNICAL ASSOCIATES, INC. Geotechnical Engineering Evaluation Stern Residence Addition July 12, 2006 NGA File No. 743106 Page 2 , . 7. Provide recommendations for site drainage and erosion control. 8. Document the results of our explorations, findings, conclusions, and recommendations in a written geotechnical report. SITE CONDITIONS Surface Conditions The property is a rectangular -shaped parcel covering approximately 2,750 square feet. The site measures roughly 55 feet in the east -west direction and 50 feet in the north -south direction. This is a zero -lot -line parcel with the land surrounding the site owned by the Homeowners' Association. The proposed development area will be within the eastern portion of the site behind the existing residence. The property is bounded to the north and south by residential properties, to the west by 73`d Place West, and to the east by undeveloped steeply sloping ground. The proposed development portion of the property is currently occupied by a second -story deck, and partially covered with cedar shrubs and ivy. Several young alder trees are located at the top of the slope. It appears that at least a portion of the ground along the top of slope was previously modified/filled to create a backyard. The slope is vegetated with scattered young to mature deciduous and fir trees, blackberries and underbrush. We observed thick tree stumps, debris, and fallen trees on the slope, but we did not observe bowing of the coniferous trees on the slope. A trail, approximately three to four feet wide has been excavated across the upper third of the slope. The bottom of the slope terminates in a ravine, which dips at an approximate inclination of 10 degrees to the north. East of the ravine, the slope continues steeply upwards. Bent conifer trees were observed on this west - facing slope. We measured the approximate inclination of the east -facing slope using a hand-held clinometer. The slope inclined at approximately 34 to 40 degrees (68 to 84 percent) and is shown as Cross-section A -A' in Figure 3. The top of the slope within the proposed development area dips moderately to the south, as shown in Cross-section B-B,' presented as Figure 4. We did not observe ponding surface water or seepage emitting from the slope during our June 15, 2006 site visit. Subsurface Conditions Geology: The Preliminary Surficial Geologic Map of the Edmonds East and Edmonds West Quadrangles, Snohomish and King Counties, Washington, by Mackie Smith (U.S.G.S., 1975) was referenced for the NELSON GEOTECHNICAL ASSOCIATES, INC. Geotechnical Engineering Evaluation Stern Residence Addition July 12, 2006 NGA File No. 743106 Page 3 geologic conditions at the site. The site is mapped as Vashon Till (Qt) and Esperance Sand (Qe). The Vashon Till is described as a non -sorted mixture of clay, silt, sand, and gravel and the Esperance Sand is described as sand with gravel and trace silt. Our explorations generally encountered dense sand with varying amounts of silt at depth, consistent with the description of the Esperance Sand. Explorations: The subsurface conditions within the site were explored on June 15, 2006 by drilling two borings to 21.5 feet below the existing surface using a portable drill rig. The approximate locations of our explorations are shown on the Site Plan in Figure 2. A geologist from NGA was present during the explorations, examined the soils and geologic conditions encountered, obtained samples of the different soil types, and maintained logs of the borings. The soils were visually classified in general accordance with the Unified Soil Classification System, presented in Figure 5. The logs of our explorations are attached to this report and are presented as Figures 6 and 7. We present a brief summary of the subsurface conditions in the following paragraphs. For a detailed description of the subsurface conditions, the boring logs should be reviewed. Both explorations encountered a surficial 4.5 to 7.0 foot thick layer of very loose to loose, brown and gray, silty fine to medium sand with varying amounts of organics and gravel. Plastic and woodchips were also encountered in these surficial soils which we interpreted as undocumented fill. Below the fill, both explorations encountered gray, fine to medium sand with varying amounts of silt, interbedded with gray, silty fine sand. This material graded from medium dense to very dense with depth and we interpreted it to be native outwash. Both borings were terminated at 21.5 feet in the outwash material. We excavated three hand augers on the slope. Hand Auger 1 encountered a surficial layer of topsoil which extended to approximately 0.5 feet below the existing ground surface. Below the topsoil, Hand Auger 1 encountered loose to medium dense, orange -brown, silty fine to medium sand, which we interpreted as native outwash. Hand Auger 1 was terminated at a depth of 4.0 feet below the existing ground surface. Hand Auger 2 encountered a surficial layer of topsoil extending 0.5 feet below the ground surface. Below the topsoil, Hand Auger 2 encountered loose to medium dense, gray -brown, silty fine to medium sand with gravel and pieces of compact silty fine sand with gravel. We interpreted this material to be slope wash. Hand Auger 2 was terminated in the slope wash material at a depth of approximately 1.5 feet. Hand Auger 3, located near the top of the slope, encountered a surficial layer of NELSON GEOTECHN/CAL ASSOCIATES, INC. ' Geotechnical Engineering Evaluation Stern Residence Addition July 12, 2006 NGA File No. 743106 Page 4 loose, gray, iron -oxide stained, silty fine sand with gravel. We interpreted this material to be fill. The fill extended to approximately 2.5 feet below the existing ground surface. Below the fill, Hand Auger 3 encountered a layer of medium dense, light brown, silty fine sand with trace gravel. We interpreted this material to be weathered native outwash. Hand Auger 3 was terminated in the weathered outwash at a depth of 3.0 feet. Hydrologic Conditions Groundwater was not encountered in our explorations; however, it is our opinion that there is potential for a perched groundwater condition to develop on this site. Perched water occurs when surface water infiltrates through less dense, more permeable soils and accumulates on top of underlying, less permeable soils. On this site, the more permeable soils would consist of loose fill and the clean native sandy materials. The less permeable materials would consist of the very dense sand with varying amounts of silt. Perched water does not represent a regional groundwater "table" within the upper soil horizons. Perched water tends to vary spatially and is dependent upon the amount of rainfall. We would expect the amount of perched water to decrease during drier times of the year and increase during wetter periods. SENSITIVE AREA EVALUATION Seismic Hazard Medium dense to very dense outwash soils were encountered underlying the site. Based on the 2003 International Building Code (IBC), the site conditions best fit the description for Site Class D. Hazards associated with seismic activity include liquefaction potential and amplification of ground motion by soft deposits. Liquefaction is caused by a rise in pore pressures in a loose, fine sand deposit beneath the groundwater table. The medium dense to very dense outwash material interpreted to underlie the site has a low potential for liquefaction or amplification of ground motion. Erosion Hazard The erosion hazard criteria used for determination of affected areas includes soil type, slope gradient, vegetation cover, and groundwater conditions. The erosion sensitivity is related to vegetative cover and the specific surface soil types, which are related to the underlying geologic soil units. The Soil Survey, Snohomish County Area, Washin on, by the Soil Conservation Service (SCS) was reviewed to determine the erosion hazard of the on -site soils. The site surface soils were classified using the SCS classification system as Alderwood-Everett gravelly sandy loam, 25 to 70 percent slopes. This unit is NELSON GEOTECHNICAL ASSOCIATES, INC. Geotechnical Engineering Evaluation Stem Residence Addition July 12, 2006 NGA File No: 743106 Page 5 listed as having a high erosion hazard for exposed soils. We consider the on -site soils on the steep slope ' to have a moderate erosion hazard in their current state with a vegetative cover. However, the erosion ' hazard on the steep slope would be severe if the vegetation were removed, or if stormwater runoff were allowed to concentrate and flow over the slope. Landslide Hazard/Slope Stability The criteria used for evaluation of landslide hazards include soil type, slope gradient, and groundwater conditions. A steep eastern -facing slope with inclinations ranging from 34 to 40 degrees (68 to 84 percent) is located in the area of the planned improvements. This slope has a vertical relief of approximately 55 feet. Significant erosion on the slope was not observed, but our explorations encountered loose fill on the top of slope and slopewash partway down the slope above a walking trail. We did not observe groundwater seepage emitting from the slope during our site visit. The core of the site slope is inferred to consist primarily of medium dense to very dense sand. Inclinations of up to 40 degrees on the slope indicate high strength and internal friction angle within the underlying unweathered soils. It is our opinion that there is not a significant potential for deep-seated slope failures within the native materials under current site conditions. Failures and erosion should be expected on the steep slope, especially within the undocumented fill if conditions are not improved. This potential could be limited through the maintenance of the vegetation on the steep slope and appropriate drainage systems. Proper site grading and drainage as well as vegetation management as recommended in this report should help improve stability conditions. It would be best to improve the density of the fill found on the slope to reduce sliding potential. We could consult with the designer and/or contractor regarding this at the time of construction. ' CONCLUSIONS AND RECOMMENDATIONS General ' It is our opinion from a geotechnical standpoint that the site is compatible with the proposed development. Our explorations indicate that a layer of loose fill underlies the area of the planned ' addition, with competent native soil deposits at depth. The planned residential addition and deck are to be constructed at least partially over sloping ground, in direct proximity to the steep slope. We consider this slope to be stable with respect to deep-seated failures, but shallow failures on the slope, especially in the undocumented fill are possible. HN/ AL ASSOCIATES INC. NELSON GEITEC C , Geotechnical Engineering Evaluation Stern Residence Addition July 12, 2006 NGA File No. 743106 Page 6 To protect the proposed development against potential failures on the slope, we recommend that the eastern and southern .foundation footing lines be supported on drilled piers. The piers should extend at least three feet into the competent native soils, and extend deep enough to provide a horizontal effective setback distance of 25 feet between the bottom of the piers and the face of the slope, as indicated by the detail in Figure 9. A minimum pier length of 12 feet should be used for axial capacity considerations. The piers should consist of a minimum of 16-inch diameter cast -in place reinforced concrete. Recommendations for design and installation of the piers are presented in the Drilled Piers subsection of this report. The northern footing line of the addition could likely be constructed using shallow foundations; however, the footings should extend at least three feet into competent medium dense native soil, and the 25-foot effective setback criteria should still be achieved. Drilled piers could be used in lieu of the northern spread footing line. Specific recommendations for shallow foundations are discussed further in the Foundations subsection of this report. In addition to maintaining the recommended setback distance, the addition should be structurally tied to the existing residence for added stability. We recommend that the planned deck be cantilevered off the residence. This would eliminate the need for deep deck footing excavations through the undocumented fill. Deck supports, if utilized, should consist of 2-inch pin piles advanced through the fill down into the native material. Pin piles should consist of schedule 80 water pipe driven using a 140-lb jackhammer. Minimum pin pile embedments of 12 feet should be achieved. Also, the piles should be driven until an advancement rate of less than one inch per minute is reached. Excavation spoils should not be stockpiled near the slope. For this site, this area would include the entire backyard. It is prudent that the contractor develop a plan for the immediate removal of the drilled cuttings from the slope during construction, and a way of catching excavated debris before heading downslope. Runoff generated within the site should be collected and routed into a permanent discharge system and not be allowed to flow over the slope. Future vegetation management on the slope should be the subject of a specific evaluation and a plan approved by the City of Edmonds. Lawn clippings and any other debris should not be cast over the slope. NELSON GEOTECHNICAL ASSOCIATES, INC. Geotechnical Engineering Evaluation stern Residence Addition July 12, 2006 NGA File No. 743106 Page 7 To improve the stability of the top of the slope area, it would be best to remove the existing fill and replace the fill with competent material. However, this may prove difficult. In this case, the fill face should be compacted using a heavy hoepack and then covered with erosion control material. The fill should be monitored, especially during the winter for any signs of movement or distress. Depending on fill performance, emergency repairs might need to be employed should fill movement be experienced. It is therefore our opinion that the planned deck should be entirely cantilevered off the residence and not be supported on pads near the fill. Future fill movement should not impact the addition if the addition is supported on deep foundations, however, future fill movement could impact any deck supports, even if pin piles are used. Slope Protection Protection of the steep slope should be performed as required by the City of Edmonds. Specifically, we recommend that the slope not be disturbed or modified through placement of any fill or removal of the ' existing vegetation. Any excavation spoils that reach the slope should be removed. Runoff should be collected in permanent catch basins or yard drains and should be routed into a permanent discharge ' system. Under no circumstances should water be allowed to concentrate or flow over the slopes. Treating the existing fill as described above should help reduce the potential for future slope movement. Erosion Control The on -site soils can have moderate to severe erosion potential, depending on how the site is graded and how water is allowed to concentrate. Best Management Practices (BMPs) should be used to control erosion. Areas disturbed during construction should be protected from erosion. Measures taken may include diverting surface water away from the stripped areas. Silt fences or straw bales should be erected to prevent muddy water from flowing over the site slopes or into the existing storm system. Disturbed areas should be replanted with vegetation at the end of construction. The vegetation should be maintained until established. Final grading should incorporate appropriate erosion control measures to route stormwater runoff away from the top of slope and into appropriate discharge locations. Structure Setbacks Uncertainties related to building along the top of steep slopes are typically addressed by the use of building setbacks. The purpose of the setback is to establish a "buffer zone" between the structure and the top of the slope so that ample room is allowed for normal slope recession during a reasonable life span NELSON GEOTECHNICAL ASSOCIATES, INC. ' Geotechnical Engineering Evaluation Stem.Residence Addition July 12, 2006 ' NGA File No. 743106 Page 8 of the structure. In a general sense, the greater the setback, the lower the risk of slope failures to impact the structure. From a geological standpoint, the setback dimension is based on the slope's physical ' characteristics, such as slope height, slope gradient, soil type, and groundwater conditions. Other factors such as historical slope activity, rate of regression, and the type and desired life span of the development ' are important considerations as well. Based upon the conditions described above, it is our opinion that the potential for shallow sloughing -type ' failures exists on the steep slope. The planned addition will be set back approximately 15 feet from the top of the slope along the northern end of the site, and constructed over the top of slope to the east. To ' reduce the risk of potential slope failures of affecting the structure, the structure should be supported on foundations extending deep enough to provide a 25-foot effective setback from the face of the slope to the bottom of the footings. This will likely mean that the southern and eastern footing lines will have to be placed on drilled piers to maintain this requirement. Site Preparation and Grading ' Site preparation should consist of the removal of the existing deck and landscaping features, then stripping any topsoil or organic fill from the development area. The stripped material should be hauled off site. The stripped material should not be stockpiled near the slope or be used for structural fill. With granular soils exposed at the ground surface, the site should be prepared for access for the drill rig. This may include importing rock spalls or crushed rock to temporarily grade the site so that the drilling equipment has access to the southern portion of the site. Also, initial access for the drilling equipment will likely be via the northern side yard. The contractor installing the drilled piers should be consulted regarding necessary site preparation for equipment access. Foundation Support Drilled Piers: We recommend that the eastern and southern foundation footing lines be supported on 16- ' inch reinforced concrete piers, extending a minimum of three feet into the medium dense or better native soils, while satisfying the recommended 25-foot effective setback from the face of the slope. Also, drilled ' piers should extend a minimum of 12 feet below the ground surface to develop sufficient axial capacity. The remainder of the foundations could be constructed using shallow spread footings extending at least ' three feet into the competent native soil. NELSON GEOTECHNICAL ASSOCIATES INC. Geotechnical Engineering Evaluation Stern Residence Addition July 12, 2006 NGA File No. 743106 Page 9 Based on the loose fill encountered in our explorations, an open hole drilling method will most likely be unfeasible. Caving conditions should be anticipated, and pile .casing will likely be required. The holes should be cleaned of any slough or water prior to pouring concrete. We recommend that the concrete be readily available on site at the time of drilling. The holes should not be left open for any extended period of time, as sloughing debris and/or groundwater seepage into the excavations may hamper pier installation. For a 12-foot deep drilled pier installed successfully as described above, we recommend using design axial compression capacities of 14 tons for 16-inch piers. We should be consulted if higher capacities are needed. Lateral resistance on the piers could be calculated based on an equivalent fluid density of 150 pounds per cubic foot (pcf) applied to two pile diameters. The upper four feet should be neglected for the purpose of calculating the lateral resistance due to the existence of loose fill. A qualified structural engineer licensed in the State of Washington should design the piers. We should be retained to review the design. Shallow Foundations: For the portion of the addition supported on shallow spread footings, footings should extend at least three feet into the native medium dense or better soils. Minimum foundation widths of 16 and 24 inches should be used for continuous and isolated spread footings, respectively, but footings should also be sized based on anticipated loads and allowable soil bearing pressure. Standing water should not be allowed to accumulate in footing trenches. All loose or disturbed soil should be removed from the foundation excavation prior to placing concrete. For foundations constructed as outlined above, we recommend an allowable design bearing pressure of not more than 2,000 pounds per square foot (psf) be used for the footing design for footings founded on the medium dense or better native soils. A representative of NGA should evaluate the foundation bearing soil prior to placing footing forms. We should be consulted if higher bearing pressures are needed. Current Uniform Building Code (UBC) guidelines should be used when considering increased allowable bearing pressure for short-term transitory wind or seismic loads. Potential foundation settlement using the recommended allowable bearing pressure is estimated to be less than one inch total and 1/2 inch differential between adjacent footings or across a distance of about 30 feet, based on our experience with similar projects. NELSON GEOTECHNICAL ASSOCIATES, INC. . Geotechnical Engineering Evaluation Stern Residence Addition July 12, 2006 ' NGA File No. 743106 Page 10 ' Lateral loads may be resisted by friction on the base of the footing and passive resistance against the subsurface portions of the foundation. A coefficient of friction of 0.35 may be used to calculate the base ' friction and should be applied to the vertical dead load only. Passive resistance may be calculated as a triangular equivalent fluid pressure distribution. An equivalent fluid density of 150 pcf should be used for passive resistance design for a level ground surface adjacent to the footing. This level surface should extend a distance equal to at least three times the footing depth. These recommended values incorporate safety factors of 1.5 and 2.0 applied to the estimated ultimate values for frictional and passive resistance, ' respectively. To achieve this value of passive resistance, the foundations should be poured "neat' against the native medium dense soils or compacted fill should be used as backfill against the front of the footing. We recommend that the upper one foot of soil be neglected when calculating the passive resistance. Frictional resistance should be neglected for footings supported on drilled piers. Site Drainage ' Surface Drainage: Final site grades should allow for drainage away from the top of the steep slope and the residence. We suggest that the finished ground be sloped at a gradient of three -percent minimum for a ' distance of aE least 10 feet away from slope and the addition. Runoff generated on this site should be collected and routed into a permanent discharge system or to the bottom of the slope. Under no circumstances should water be allowed to flow uncontrolled over the slope. Subsurface Drainage: If groundwater is encountered during construction, we recommend that the contractor slope the construction area and collect the water into ditches and small sump pits where the water can be pumped out and routed into a permanent storm drain. We recommend the use of footing drains around structures. Footing drains should be installed at least one foot below planned finished floor elevation. The drains should consist of a minimum four -inch -diameter, rigid, slotted or perforated, PVC tpipe surrounded by free -draining material wrapped in a filter fabric. We recommend that the free - draining material consist of an 18-inch-wide zone of clean (less than three -percent fines), granular material placed along the back of walls. Pea gravel is an acceptable drain material or drainage composite may also be used instead. The free -draining material should extend up the wall to one foot below the finished surface. The top foot of soil should consist of impermeable soil placed over plastic sheeting or building paper to minimize surface water or fines migration into the footing drain. Footing drains should discharge into tightlines leading to an appropriate collection and discharge point with convenient cleanouts to prolong the useful life of the drains. Roof drains should not be connected to footing drains. ' NELSON GEOTECHN/CAL ASSOCIATES, INC. Geotechnical Engineering Evaluation ` Stern Residence Addition July 12, 2006 NGA File No. 743106 Page 11 USE OF THIS REPORT NGA has prepared this report for Mr. David Stern and his agents for use in the planning and design of the development planned on this site only. The scope of our work does not include services related to. construction safety precautions and our recommendations are not intended to direct the contractors' methods, techniques, sequences, or procedures, except as specifically described in our report for consideration in design. There are possible variations in subsurface conditions between the explorations and also with time. Our report, conclusions, and interpretations should not be construed as a warranty of subsurface conditions. A contingency for unanticipated conditions should be included in the budget and schedule. We recommend that NGA be retained to review final project plans and provide consultation regarding structure placement, drilled pier capacities, setback distances, and foundation support. We also recommend that NGA be retained to provide monitoring and consultation services during construction to confirm that the conditions encountered are consistent with those indicated by the explorations, to provide recommendations for design changes should the conditions revealed during the work differ from those anticipated, and to evaluate whether or not earthwork and foundation installation activities comply with contract plans and specifications. We should be contacted a minimum of one week prior to construction activities and could attend pre -construction meetings if requested. All people who own or occupy homes on hillsides should realize that landslide movements are always a tpossibility. The landowner should periodically inspect the slope, especially after a winter storm. If distress is evident, a geotechnical engineer should be contacted for advice on remedial/preventative measures. The probability that landsliding will occur is substantially reduced by the proper maintenance of drainage control measures at the site (the runoff from the roofs should be led to an approved discharge point). Therefore, the homeowner should take responsibility for performing such maintenance. Consequently, we recommend that a copy of our report be provided to any future homeowners of the property if the home is sold. ' Within the limitations of scope, schedule, and budget, our services have been performed in accordance with generally accepted geotechnical engineering practices in effect in this area at the time this report was prepared. No other warranty, expressed or implied, is made. Our observations, findings, and opinions are ' a means to identify and reduce the inherent risks to the owner. NELSON GEOTECHN/CAL ASSOCIATES, INC. Geotechnical Engineering Evaluation Stern Residence Addition July 12, 2006 NGA File No. 743106 Page 12 It has been a pleasure to provide service to you on this project. If you have any questions or require further information, please call. Sincerely, NELSON GEOTECHNICAL ASSOCIATES, INC. CdV1�-----X W Calvin A. McCaughan, EIT Senior Staff Engineer Khaled M. Shawish, PE Principal CAM:KMS:lam Nine Figures Attached NELSON GEOTECHNICAL ASSOCIATES, INC. VICINITY MAP N Not to Scale 2 a/ '�YYji 3 } .fi ¢•.,Jw 3�1+9 Rr S P ar' iF •"�€` ..'�L `^q� ' �;y a6f�K..:{{F¢ ,54®r, t, b z&'t gi itB { G�3 A ,,,.'„ 1 l� .M }tom .i Y.•`r t i'l�'�'a t _ d� �2�.` 1 y 4 5t 3S r 54 ,r a �r�a'�, 3Z' rae�y 4 r, t �, � '8•. ,Rq 4 yin ems._ 9 Edmonds, WA Project Number NELSON GEOTECHNICAL No. Date Revision By CK 743106 Stem Residence Addition jV ` A ASSOCIATES, INC. M orfamw aco ewc Vicinity Map GEOTECHNICAL ENGINEERS & GEOLOGISTS Figure 1 (QM4W18W1FaxI01-W10 Z Q N \ — HA-1 \ — — HA-2 Approximate B-1 top of slope �A-3 Proposed Upper Level Cantilever eck B-2 \ B F---_--� j \\ B1 —I Proposed Two - Level Addition I Existing 2-ft. Existing high rockery � deck to be removed / Existing ," wall to be removed I Existing Two -Level Residence Existing Upper Level Deck 73rd Place W. LEGEND HA-1 Number and Approximate • e Property Line + Location of Hand Auger 0 10 20 B-1 A X Approximate Location Number and Approximate t_J of Cross- Section —+— Location of Boring Scale: 1 inch =10 feet a Reference: Site Plan based on a plan dated May 16, 2006, titled "Existing Residence: David and Darlene Stem," prepared by LOT Design Group. o Project Number NELSON GEOTECHNICAL No. Date Revision By CK 743106 Stem Residence Addition NGA ASSOCIATES, INC. 1 6n7ro8 OrIgNEd ACO EHK Site Plan G6OTBCHNICAL ENGINEERS & GEOLOGISTS Figure 2 17VWhA:w337 VibLA0 (42fi)4W1W91Fet491.W10 — Z � � � � � a� �� iiiiiii�r �■ A � � � � J• � � 71 co o q qy w Q West I I cD East 80 - .. 6 03 B_2 (Projected 10 ft. South) . a Existing B-1 (Projected 10 ft. North) M Residence R �\•`� WCD60 - fill ; 60 �► 7 :7 r .. 20 CL O _ 14 t Y o O O f i O 440 i 40 W r y Medium dense to very j L t "� o Z"dense outwash soils ti HA Slopewash .1 f x gPI p>i Z yy� a i 20 L ^f: �.• 4,' f I S t..15 ,¢y 7 �:�,.. / M' m IV Z �( f t1 Jr 'f _!,. .M f g �h r ". Z > a +fie z(A n} r r tit ti r PI HA PI Z O i) U^ / s 7t Q 0 G A 0 l l l l i l l l l i l l t l i l l l l l 9 n 0 20 40 60 80 160 120 140 1 r Distance (feet) Exploration v S Boring Designation _—� B-1 23 20 0 m 23 � SPT N-value NOTES: co Groundwater Level 23 1) Stratigraphic conditions are interpolated between During Exploration 23 the explorations. Actual conditions may vary. Geologic contact ? 23_ —? 2) Elevations are arbitrary. .�° (approximate) m A X Reference: Cross Section is based on field measurements using a hand-held clinometer and 100-ft tape measure. m" 2006V43106 SternWNAwg M M ro -n o c o 3 m HA-3 (Projected 8 ft. CA 40 1 3 3 R Existing Rockery n� B' South T 40 CO W77 �' pp, n 7 C M 30 i B-2 R J ^ b r rY �_ ° Fill 1 r > E• L r t ` ,Medium dense to verya " s c w 20 dense-outwash soils r Z a >� g in n 120 ^ { -s - f `} J t 7 L t', `f's t a f t 1 1• ., . b bS t J 220055 F Z Q 1 10 a mo r Y Y F m am 4, r 9 J rx d 1 -1 � )f d i t F A O J. Z { �n I I I r l l l l l l l l r r r t t t t r 0 10 20 30 40 50 Exploration Z o Distance (feet) 30 10 it v � Boring Designation B-1 E-- SPr N-value NOTES: I Groundwater Level —� � 1) Stratigraphic conditions are interpolated between During Exploration the explorations. Actual conditions may vary. Geologic Contact ---> ? 23_ —? 2) Elevations are arbitrary. I(approximate) Reference: Cross Section is based on field measurements using a hand-held clinometer and 100-ft tape measure. zoos��a3�os sren,�e s1.4 wa 1 1 1 1 UNIFIED SOIL CLASSIFICATION SYSTEM - GROUP MAJOR DIVISIONS GROUP NAME SYMBOL CLEAN GW WELL -GRADED, FINE TO COARSE GRAVEL COARSE- GRAVEL GRAVEL GP POORLY -GRADED GRAVEL GRAINED MORE THAN 50 % GRAVEL GM SILTY GRAVEL OF COARSE FRACTION SOILS RETAINED ON NO.4 SIEVE WITH FINES GC CLAYEY GRAVEL SAND CLEAN SW WELL -GRADED SAND, FINE TO COARSE SAND SAND SP POORLY GRADED SAND MORE THAN 50 % RETAINED ON MORE THAN 50 % NO.200 SIEVE OF COARSE FRACTION PASSES NO.4 SIEVE SAND SM SILTY SAND Sc WITH FINES CLAYEY SAND FINE - SILT AND CLAY ML SILT INORGANIC GRAINED LIQUID LIMIT CL CLAY LESS THAN 50 % SOILS ORGANIC OL ORGANIC SILT, ORGANIC CLAY SILT AND CLAY MH SILT OF HIGH PLASTICITY, ELASTIC SILT INORGANIC MORE THAN 50 % PASSES LIQUID LIMIT CH CLAY OF HIGH PLASTICITY, FLAT CLAY NO.200 SIEVE 50 % OR MORE ORGANIC OH ORGANIC CLAY, ORGANIC SILT HIGHLY ORGANIC SOILS PT PEAT NOTES: 1) Field classification Is based on visual SOIL MOISTURE MODIFIERS: examination of soil In general accordance with ASTM D 2488-93. Dry - Absence of moisture, dusty, dry to the touch 2) Soil classification using laboratory tests Is based on ASTM D 2488-93. Moist - Damp, but no visible water. 3) Descriptions of soil density or Wet - Visible free water or saturated, consistency are based on usually soil Is obtained from Interpretation of blowcount data, below water fable visual appearance of soils, and/or � test data. ; Project Number NELSON GEOTECHNICAL No. Date Revision By CK 743106 Stem Residence Addition Soil Classification Chart NGp ASSOCIATES, INC. GEOTECHNICAL ENGINEERS & GEOLOGISTS 1 ene/0s Odg[W Aco EHK Figure 5 1"11-188N Avs. NE A = Wmd6r, WA880T2 OrohomW Cau dy (/Pb i97-,8� WauldiWChWn(9W 78/,TIBB 0 (428) 4W18881 Fax481,Y8,0 www I I I I 1 I I I I I I I BORING LOG B-1 Approximate Ground Surface Elevation: Soil Profile Sample Data Penetration Resistance (Blows/foot - 0) Plazometer 10 20 30 40 50 50-- 1! Installation Description A2 CIL CL 0 C 0 ;M L� Ground Water Data _' _J -4 . Moisture Content 120 E 2 E >1 r 8 E - 9 U) Percent - 0) S (Depth in Feet) Cn _J 8 10 20 30 40 50 50-t Light brown, silty fine sand with organics and woodchips :' 5 (loose, moist) (FILL -slightly iron -oxide stained, very loose SM 3 -with trace gravel 6 5 ... .... ......... ........ ......... ......... ........ 5 — — — — — — — — — — — — — — — — Light brown, iron -oxide stained, silty fine to medium sand trace dense, -- SM 12 with gravel (medium moist) Brown -gray, iron -oxide stained, fine to medium sand with silt and gravel (medium dense, moist) SP-SM 14 10 ........ ... .... ........ ......... ......... ........ -10 -- — — — — — — — — — — — — — — — — Gray, silty fine to medium sand with gravel (dense, moist) 43 SP 15 ........ ......... ........ ........ ... ........ -15 — — — — — — — — — — — — — — — -- Gray, fine to medium sand with silt and trace gravel L._*—b ;6: — (dense, moist) -- SP-SM 38 — — — — — — — — — — — — — — — — Grey, silty fine to medium sand with trace gravel - - — 20 ........ ......... ...... . ..... ... ........ ........ 20 (dense, moist) SM 37 Boring was terminated below existing grade at 21.5 feet on 6115/06. Groundwater seepage was not encountered during drilling. 25 ........ ......... ........ ......... ........ ........ -25 LEGEND ❑ Solid PVC Pipe Concrete M Moisture Content ❑Slotted PVC Pipe A Afterberg Limb Depth Driven and Amount Recovered Bentonita G Grain -size Analysis with 2-inch O.D. Split -Spoon Sampler Monument/ Cap tt�Native Soil DS Direct Shear to Plazometer Silica Sand PP Pocket Penetrometer Readings, tons/ft Depth Driven and Amount Recovered Liquid Limit P Sample Pushed 3-inch Shelby Tube Sampler with + Plastic Limit i Water Level T Tflaxial NOTE: Subsurface conditions depicted represent our observations at the time and location of this exploratory hole, modified by engineering tests, analysis and judgement. They are not necessarily representative of other tknes and locations. We cannot accept responslbflfty for the use or interpretation by others of Information presented on this log. Project Number NELSON GEOTECHNICAL No. By CK 743106 Stem Residence Addition -_'e�NGA ASSOCIATES, INC. Boring Log GECOTECHNICAL ENGINEERS & GE . OLOGISTS 1731i-iU1hA-NE.X= Woodhr4b.WAWM (425) 48&1869 1 FaX481-2510 1 W28M MDateRevislon Original AM EHK Figure 6 Page 1 of 1 • BORING LOG B-2 Approximate Ground Surface Elevation: Soil Profile Sample Data Penetration Resistance (Blows/foot - 0) a Piezometer 10 20 30 40 50 50+ Installation - Descrilion p r C n $ ; c 1 m c a S E r�' Z ° L° Ground Water Data Moisture Content (Percent -1 m 3 (Depth in Feet) c7 O rn 10 20 30 40 50 50+ ISO Topsoil loose moist 3 Gray, silty fine to medium sand with organics, gravel, and pieces of plastic (very loose to loose, moist) FILL SM 4 — — — — — — — — — — — — — — — F Brown -gray, iron -oxide stained, silty fine to medium sand ; -7771 — 5 ......• 5 with trace gravel (medium dense, moist) 20 ' SM -grades to dense ` -= •'. , • ,T 44 Grey, fine to medium sand with trace silt and trace gravel 10 10 interbedded with gray, silty fine to medium sand ::' •' 54 ' (very dense, moist) ; •;' ,.: SP/SM •... :.,. 15 ............................... ... 15 76 — — — — — — — — — — — — — — Gray, fine sand with silt (very dense, moist) — :• 78 Boring was terminated below existing grade at 21.5 feet on 6/15/06. Groundwater seepage was not encountered during drilling. 25 ................................................... 25 LEGEND ❑ Solid PVC Pipe Concrete M Moisture Content Depth Driven and Amount Recovered ❑ Slotted PVC Pipe +; Bentonite A Atterberg Limits Wwith 2-inch O.D. Split -Spoon Sam ler Monument/ Ca G Grain -size Analysis p p � Native Soil DS Direct Shear to Piezometer i Driven and Amount Recovered * Liquid Limit Silica SandPPPp Pocket Penetrometer Readings, tons/ft p Sample Pushed I Water LDepth with 3-inch Shelby Tube Sampler + Plastic Limit = T Triaxial 1 NOTE: Subsurface conditions depicted represent our observations at the time and location of this exploratory hole, modified by engineering testa, analysis and Judgement. They are not necessarily representative of other times and locations. We cannot accept responsibility for the use or interpretation by others of information presented on this log. i i Project Number NELSON GEOTECHNICAL No. Date Revision By CK 743106 Stem Residence Addition NGA ASSOCIATES, INC. Boring Log GEOTECHNICAL ENGINEERS & GEOLOGISTS tnttd� wA SM w we _ �re zrm .. t eneas Orighw ACO EKK a S Figure 7 Page 1 of 1 (.�.Be-ta39,�,at.,sta „ .r LOG OF EXPLORATION DEPTH (FEET) USC SOIL DESCRIPTION HAND AUGER ONE 0.0 - 0.5 0.5 - 3.5 3.5 - 4.0 HAND AUGER TWO 0.0 - 0.5 0.5 - 1.5 HAND AUGER THREE 0.0 - 0.2 0.2 - 2.5 2.5 - 3.0 EHK:ACO DARK BROWN, SILTY FINE SAND WITH ORGANICS AND ROOTS (LOOSE, MOIST) (TOPSOIL) SM ORANGE -BROWN, SILTY FINE TO MEDIUM SAND WITH TRACE SAND, TRACE ORGANICS, AND TRACE ROOTS (LOOSE TO MEDIUM DENSE, MOIST) SM GRAY -BROWN, IRON -OXIDE STAINED, SILTY FINE TO MEDIUM SAND WITH TRACE GRAVEL AND TRACE ORGANICS (MEDIUM DENSE, MOIST) SAMPLES WERE COLLECTED AT 2.0 AND 3.9 FEET GROUNDWATER SEEPAGE WAS NOT ENCOUNTERED HAND AUGER CAVING WAS NOT ENCOUNTERED HAND AUGER WAS COMPLETED AT 4.0 FEET ON 6/15/06 DARK BROWN, SILTY FINE SAND WITH ORGANICS AND ROOTS (LOOSE, MOIST) (TOPSOIL) SM GRAY -BROWN, SILTY FINE TO MEDIUM SAND WITH GRAVEL AND PIECES OF SILTY, FINE SAND WITH GRAVEL (LOOSE TO MEDIUM DENSE, MOIST) (SLOPE WASH) SAMPLE WAS COLLECTED AT 1.4 FEET GROUNDWATER SEEPAGE WAS NOT ENCOUNTERED HAND AUGER CAVING WAS NOT ENCOUNTERED HAND AUGER WAS COMPLETED AT 1.5 FEET ON 6/15/06 DARK BROWN, SILTY FINE SAND WITH ORGANICS AND ROOTS (LOOSE, MOIST) (TOPSOIL) SM GRAY, IRON -OXIDE STAINED, SILTY FINE SAND WITH GRAVEL (LOOSE TO MEDIUM DENSE, MOIST TO WET) (FILL) SM LIGHT BROWN, SILTY FINE SAND WITH TRACE GRAVEL (MEDIUM DENSE, MOIST) SAMPLES WERE COLLECTED AT 2.0 AND 2.9 FEET GROUNDWATER SEEPAGE WAS NOT ENCOUNTERED HAND AUGER CAVING WAS NOT ENCOUNTERED HAND AUGER WAS COMPLETED AT 3.0 FEET ON 6/15/06 NELSON GEOTECHNICAL ASSOCIATES, INC. FILE NO 743106 FIGURE 8 P. Typical Foundation Effective Setback Detail (Not To Scale) Footing Deepen footing excavation achieve the recommended setback from face of slope, or use drilled piers with a minimum 12-foot depth to achieve setback. VALGI I%A F/IG-i1 .7 Gi 1/III III l lu, I VI three feet below bottom of fill. Minimum 25-foot Horizontal distance from face of slope Project Number NELSON GEOTECHNICAL No. Date Revision By CK ` 743106 Stem Residence Addition NGA ASsoclArEs, INC. 1 7/10/06 odemai ACo cAnl Foundation Effective Setback GEOTECHNICAL ENGINEERS & GEOLOGISTS Figure 9 „n ,W1hA».NF AM 8= W=l WA 4Me1- MfamtllredGwmn ((16�)7B4T/H0 Q '(�) �B&1BBB / Fax x81-26,0 rrYnvn�aoW�.aom (7 CL U �4 U ' � O Ti mm Cd V 6 °0, ■ V♦ :C 0 0 �_0 0 Lo W f!I 00 N U ® > Q QO 00 REV. O1/09I2007 REV.01/09/2007 c m � o SILT FENCE LINE do N •C; .0 N w a 0 50'-0" CORNER ORIGINAL 331.94 EXTERIOR STAIRWAY CORN ORIGINAL 318.74' REV. 01/09/2007 Lpi REV. 01/09/ E 331.94' — — — —i NEW DECK REV. 01/09/2007 (ORIGINAL) 318.74' (B) HEIGHT CALLS;. (NEW ADDITION) (ORIGINAL) C = 331.75' 325.30' =NN = 331.94' NEW ADDITIO 318.74' TOTAL = 1,307.73' - 4 = 326.9325' p R GINAL5' O I I MAXIMUM: 25.00' + 326.9325' = 351.9325' 325.30' WW REV. 01/09/2007 (RIGINAL) z RESIDENCE TOP OF RIDGE i I a EXISTING BUILDING = 354.9800'ccp THE ( NORTH SIDE) IS 30' FROM ANY STRUCTURE ( i v ADDITION MAXIMUM = 351.9325' w THE (SOUTH SIDE) IS 15' FROM ANY STRUCTURE THE (EAST' END)' IS 400'+ FROM ANY STRUCTURE �� zNEW ADDITION MUST BE -3.0475(3-0 s ) I6 O 00 U LOWER THEN EXISTING RIDGE. THE (WEST END) IS 45 FROM ANY STRUCTURE Z I a DESIGN T-1" LOWER THEN EXISTING CCD cc FIELD VERIFIED AT TIME OF FRAMING tmi J L In F1106 i uta" p HEIGHT CALLS. (EXISTING RESIDENCE) p • = 331.25' p� = 332.65' C 3 tmi Z REV. 01/09/2007 EXISTING RESIDENCE = .75' I I I D = 325.30 TOTAL = 1,320.95' - 4 = 330.2375' EXISTING BUILDING SITE (NOT A LOT) I MAXIMUM: 25.00' + 330.2375' = 355.2375' ACTUAL 23.25' = 354.9800' w EAGLES NEST DIV. 2 BUILDING SITE 15. ----------------- I I REV.O1/09/2b07 IMPERVIOUS SURFACE CALCULATIONS N/A man 30'-0" 20'-0" NOTE: � � ' urn I ALL STRIPPED MTERIALS SHALL BE HAULED 14,, t GAILS • I FROM THE SITE. NOT STOCKPILED FOR RE- A-331.25' —� - - _ - - - - - - -�—T B-332.65 �32.5 USE AS PER GEOTECH REPROT �J "1 (ORIGINAL) (ORIGINAL)-- FIRE HYDRANT EXISTING 3ti• EXISTING NEW TOTAL DRIVEWAY "Moths g i t Pe itoapproval proem shall be ,A : ? 3 I • 2�' Living Area: interpreted allowing permitting the any aintenance of any cur rents existingill nconforming �'� _ --- I �) 4. 5 � •� + 2 � 3 FS • LP Lower Level 828 Sq.Ft. 335 Sq.Ft. 1,163 Sq.Ft. or building, o site condition which is outside the scope of the A-V-�'i 61 gP� G� d � � p Upper Level 1,688 Sq.Ft. 552 Sq.Ft. 2,240 Sq.Ft. a it application, regardless of whether such Gy Total Living Area 3,403 Sq.Ft. REV. 01/09/2007 uil in structure or condition is shown on the site pp g'or drawing. Such building, structure or I f — '{" Z 5 p Garage: Lower Level 605 Sq,Ft. 605 Sq.Ft. NOTE: condit n maybe the subject of a separate enforce ent action." p� Shop FILTER SOCKS ARE REQUIRED IN ANY = 36 3 . t0 45 • Lower Level Deck 162 Sq.Ft. 286 Sq.Ft. 448 Sq.Ft. CATCH BASINS IN THE VICINITY OF THIS PROJECT z Max t-+e,i 5 VW Upper Deck 240 Sq.Ft. 210 Sq.Ft. 450 Sq.Ft. 1�a,,�`i� w .. L__ Basement level Storage 254 Sq.Ft. 254 Sq.Ft. q q f l,Z:.:� = U LOT LINE STAKES MUSTf: \ o BE IN PLACE AT TIME OF F_r` E ! l� o OWNER/CONTIVkL'1 CAR IS RESPONSIBLE FOR EROSION h p CONTROL AND DAMAGE BUILDING SITE PLAN EXISTING/PROPOShD CONTENTS PARCE NUMBER 007415 000 015 00 SITE PLAN EAGLES NEST DIV,2 BLK 000 D-00 EXISTING & PROPOSED LOT 15 ; ,*SCALE 1 /8" = 1'-0" - 24 � Banc P-D' 1 -1 $1 .2. x 36 bach Corner oFla �® ' SCALE 1 16 " = 1 ' - 0" - 12 x 18 R Wired Front SDA 4422 Sides p Re Other DATE -hJJOw l(ZW mnr�n CL6V i � s A a5 hof-ed M APPROVED BY PLANNING, �He___ fight v 5 � — 09/07/06 9 Q,0-1-Lc,(n to i ca t 1(, ovf• c�g�,t� nti -o t • o �- REV.01/09/07 Drawing No. S`TR`EET FILE . IA �� l� 2ooa �Ur QlNr 3 yOP FEW [Ui j Gt--. I m ti- EFU HLE RR8u I Dal JAN 19 2007 LD3NO D� ffqT ELEV. 33' 1 (ADI ELEV. 331.25 1. ELEV. 33: 50'-0" F////FLOOR ELEV. @ EXISTING MINIMAL /// CUTS/FILLS STORAGE AREA 8.5 BELOW FIRST FLOOR 4' 15.30' .U.u1i V . UJG. PuUNDATIO""N PLAN SCALE 1 /4" = 1'-0" 24x36 SCALE 1 /8" = 1'-0" 12x18 �► CAS 0141 CALULATIONS 2 ® MINMAL FLOOR AREA 4 = 308 FT3 = 11.5 YRDS FILL 11.5 YRD3 FILL TOP VIEW 41 22' 21 FILL 2 � 11� STORAGE ELEV. CUT ® 13.5 YRD3 CUT 4, 4 2 1 GRADE 13.5 YRD3 FILL CUT= 22x2xl l/2 + 1/2 22'x2xll/2 = 363'CUT = 13.5 YRDS3 = 13.5 YRDS FILL IMPORTED SLAB ROCK AND SAND 6"x50'xll + 6"xl2'x6' = 11.5 YRDS3 FILL 11.5 YRD3 FILL PIERS 16" IA 10 PIERSxl2x7(.666)2 = 6.2 YRD3 6.2 YRD3 CUT 12' FOOTINGS/SPRED 1 @ 12' LONG x 4' DEEP @ 1'8" WIDE _ .69 YRD3 > 2YRDS 2 @ ll' LONG x 8' DEEP @ 1'8" WIDE = 1.17 YRD3 2 YRD3 CUT TOTAL YARDg = 36.5 FIL - 22 CUT = 14.5 NET FILL YARD BASED ON CALCULATIONS BY: Calvin A. McCaughan E.I.T. Senior Staff Engineer NALSON GEOTECHNICAL ASSOCIATES, INC. 17311 - 135th Ave. NE., Woodinville, WA 98072 425.486.1669 fax 425.481.2510 calvinm@nelsongeotech.com r STrm"'EET FILE 0 Z � 0 2007 "uC;i�oFEDM�Q � Q:\AutoCad Working\DAVID STERN\DAVID STERN F REV, 01.15.2007.dwg, 2/20/2007 9:48:48 AM, \\mobile\HP DesignJet 500 24 by HP 64011716 a��&Oov-s S- l3 iEET FILE r�� "Li �� yS CEO FEB 2 0 2007 S L-W& EDMOf 02-15-'07 16:01 FROM -Nelson Geotecbnical 425-481-2510 T-557 P002/002 F-186 f,L.9 NO. DATA $AEFT__I_. • :F So AL V NELSON G80TECHNICAL ASSOCIATES1 INC. U52 FEB 2 0 2007 aULD,NG0RpAFTrA4 C'T'Ycw=EEDm0j\j mqy 02-15-'07 16:01 FROM -Nelson Geotechnical 425-481-2510 T-557 P001/002 F-186 JOB FILE NO. . DATA ' ! 1F T : - OAF - ME PC bA- . Z! �. x NELSON GEOTECWNICAL ASSociATSS. mc. FEB 20 2007 / Of f�Y pF EDMQNEr