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15604 75TH PL W.PDFlillIIII lill IIIII lill6034 15604 75TH PL W J ADDRESS: (/J �/`'T / G- h _ TAX ACCOUNT/PARCEL NUMBER BUILDING PERMIT (NEW STRUCTURE): COVENANTS (RECORDED) CRITICAL AREAS:. ! S ` ` / DETERMINATION: []Conditional Waiver AStudyRequired ❑ Waiver DISCRETIONARY PERMIT #'S: � ` / 1' 3- ^00 . V--q-01 DRAINAGE PLAN DATED: PARKING AGREEMENTS DATED: EASEMENT(S) RECORDED FOR: PERMITS (OTHER): IM41 36-/ 644y6 . ��CIS f!S6 G% CL(�4'IOT�:Da3�6�f� / h et A 2 003--0649 Ajed &✓jNdayecl, 20"136 Q�C.Y, p, 2oo �1-d1,3; pi a PLANNING DATA CHECKLIST DAI SCALED PLOT PLAN DATED: Z SEWER LID FEE $ SHORT PLAT FILE: J rL%1 -7 �� L�r LOT: SIDE SEWER AS BUILT DA SIDE SEWER PERMITS) #: 0 74t " GEOTECH REPORT DA' STREET USE / ENCROACHMENT PERMIT #: WATER METER TAP CARD DATED: LID #: -2L f, � 1 i3Ido /Jl Vy/ovi%1 /'�t Gq,-Vkk *C•u pce caV BLOCK: LATEMP\DSTsTorms\Street File Checklistdoc Date: To: From: Subject: MEMORANDUM March 11, 1999 Jeannine Graf, Building Official Jim Waite, Water/Sewer Supervisor Single family home at 15604 75 PL W. E Theresa Aldridge at 15604 75'h PI. W. has submitted for a building permit. There is a grinder pump station for sewage, which exists for the home she demolished. The discharge line for the grinder pump station is only 1'/2 feet deep in places and we are concerned that excavation may damage this line. Please have Ms. Aldridge address the following items before issuing a building permit: Show on the plans for the new house the new location of the grinder pump station, which she will be responsible to move at her expense. Replace the sewer discharge line, also at her cost. If this property is ever subdivided, the sewer discharge line will probably have to be relocated at Ms. Aldridge's expense. C:\WORDATA\Memos\JeannineAldridge. DOC cr 00 _o a) Ln a� ` CITY of EDM.�DS ��® 'I�IL�ForInspection Call 77MEff UBL� WORKS Address of Construction: r? SJJE SEWER. PERMIT WP PERMIT NO. 07609 GQ1m0C.R PUMP. DEL►6vc RED 3-►,7-8G V `.. L. �y MNW00D LINE Property Legal Description (Include all easements): Owner and/or Builder: Contractor & License No: 9/✓/W_V �0 I/VS q-/! Ft )ST Single Family Residence, Multi -Family (No. of Units ) Commercial (No. of fixture Units ) Invasion into City Right -of -Way: No �'" 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 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 Date with the items listed on the back. Permit Fee:.('U Issued By: Trunk Charge: ZSQp Date Issued: 3�/��8� Assessment Fee: Receipt No.: Partial Inspection:• 13AC-KFILL Ki6 4.3-86 Comments DateInitial ty STP.Tr TIF- G . I N SP. Final Inspection Approved: � AO.R'iAN �LN,.\ Date Initial g-SG °t1'707 5 2 Rejected: Keason ** PERMIT MUST BE -POSTED ON JOB.SITE ** Date Initial f_, Wh.ite Copy - File Green Copy - Inspector Buff Copy -.Applicant W " A -4 d o � z I~ zz U O a , p U� O z 1" a O U � A Ha z ow 2p3O� = J a °s 4 d e/ W 11 ~ Apo c 9d 2 0 zo �Q 1 \ ► , 7 i I � � ♦ f Y , 1 � � W I qa a ► I 7 1 or ii 1 ► i11 aW ► ' ► 1 1 d ° I I � � � I o 1 1Ui ci •: I I 4 QY Oka �J - ► ��• a-� :� m O fix � i 0 1 �$ r I 1 � 1 Q- L 1 � ON a CA Fif P No- %.,ritical Areas Checklist Site Information (soils/topography/hydrology/vegetation) L 1. Site Address/Location: 2. Property Tax Account Nui er: 0 E Number: _Sj 3jCnf)10,2q. nsosl 3. Approximate Site Size .(acres or square feet): I ArjeoF" 4. Is this site currently developed? X yes, no. If yes; how is site developed? wn.'V 't .5. Describe the general site topography. Check all that apply., Flat: less than 5-feet elevation change over entire site., Rolling-- s opes on site generally less than 15% (a vertical rise of 10-feet Over a 'horizontal distance of 66-feet). (Z Hilly:- slopes piese'nto!:n,site ` of more than 15% and less than 30% a vertical rise,',!-,,, of 10-feet over a horizontal distance of 33 to 66-feet). Steep::: grades of greater than 30% present on site (a vertical rise of 10-feet over a horizontal distance of less than 33-feet). Other (please describe): 6. Site contains areas of year-round standing water: A16 Approx- Depth: 7. Site Contains areas of seasonal standing water: Approx. Depth: What season(s) of the year? 8. Site is in the floodway floodplain A)n of a water course. 9. Site contains a creek or an area where water flows across the grounds surface? Flows are year- round? 412- Flows are seasonal? AI)4- (What time of year? 10. Site is primarily: forested meadow ;shrubs ;mixed urban landscaped (lawn,shrubs etc) 1-1. Obvious wetland is present on site: RcVOIA)04 I .t 6, 3.i-9 •r�zV4 �y.' _t- '') t''�� ;6.ir.i .gin ri.`.�• ICA City of . Edmonds Critical.'-Areas.,,,--.Che"cklist. The Critical AreasChecklist-contained; on, ;7 and -submit it to'the City. The City will this form is to tbe, filled out by. any,person : ,N ; n? ;j review the.+checklist, make a precursory site preparing'a Development Permit _,-visit,.aPd make a determination of the Application for the,City of Edmonds prior subsequent steps necessaryr to complete a to his/her- submittal •of a' development,,:, development permit application.- -' permit to the City. ' With a signed copy 'of this form,. the The purpose of the Checklist is to enable ' °' = applicant should -also submit a vicinity map City staff to`determine whether any. or plot plan for individual lots of the parcel potential Critical Areas are or may be _ _ .., with enough detail that City staff can find present on the subject property. The and identify -the subject parcel(s). In information needed to complete the addition, the applicant shall ' include .. Checklist should be easily available from other.pertinent information (e.g. site observations of the site or data available at plan, topography map, etc.) or studies in City Hall (Critical Areas inventories, maps, conjunction with this Checklist to assist or soil surveys). staff in completing their preliminary. �.:. amassment of the site. An applicant, or his/her representative; must fill out the checklist, sign and date it, ' I have completed the attached Critical Area Checklist and attest that the answers provided are factual, to the best of my knowledge (fill out the appropriate column below). -- I Owner / Applicant: Applicant Representative: oglo GC S o�✓ I Name Name 707c .---L g rk ,eyeal Street Address StreetAddress ,... ,.: City, State, ZIP = '' vie t •} Phone CityState, ZIP , . Phone. �I��ZY�'Y/'r . '' (ice �� . _ " :11 k. •: - " - -.._ . _ Signattdd. Date - Date . Signature f ' _t'3 tii ltiA°^}1�t.'' - t L- t Y.a •! \ 6; t {. Y: Yr > } t y- may' f t J i City of Edmonds Critical Areas Determination Applicant: Torkjel Carlson Determination #: CA-95-111 Project Name: Permit Number: Site Location: 15604 75th Place West Property Tax Acct #: 5131 000 024 �08 Project Description: Non -Project Specific Determination: Study Required: During review and inspection of the subject site on June 14, 1995, it was found that the site contains a Steep Slope Hazard Area pursuant to Chapter 20.15B of the Edmonds Community Development Code (ECDC). Based on these findings, prior to submission of any development permit, you will be required satisfy the requirements of ECDC 20.15B by completing the following: Before any permit application may be submitted, submit to the Planning Department a topographic survey prepared by a Licensed Land Surveyor delineating Steep Slope Hazard Areas. Any slope over 40% with more than 20 feet of rise will be classified as a Steep Slope Hazard Area. A 50 foot buffer is required from both the top and toe of the slope. A 15 foot building setback is required from the 50 foot buffer. For development of any kind which is proposed within the critical area, 50 foot buffer or 15 foot buffer setback, it must be shown that the development will not adversely impact the Critical Area or its buffer, by doing one or possibly both of the following depending on the outcome of the study: For development proposals which will occur within the 50 foot buffer, but no closer than 25 fdet from the top or toe or the slope, the 50 foot buffer requirement may be reduced to 10 feet if a study is completed by a licensed geologist or geotechnical engineer which clearly demonstrates that the proposed buffer alteration will have no adverse impact upon the site, the public or any private party. All Critical Area Studies must be completed under a three party contract where the City hires the professional required, and the applicant pays for the study (pursuant to ECDC Section 20.15B.150). 2. If development must occur within the critical area, buffer, and/or buffer setback, and is not identified as an exception per ECDC Chapter 20.15B, a Reasonable Use Exception and Variance must be obtained pursuant to ECDC 20.15B.180A and 20.15B.040C). All proposed development of the .subject lot must meet the requirements of Chapter 19.05 of the Edmonds Community Development Code. If the property owner wishes to apply for a, specific development permit which they feel would not impact the Critical Areas located on the site, they may submit their proposal to the Planning Department for review. If the Planning Department finds that the proposed development permit will not.adversely impact a Critical Areas or its buffers, a conditional waiver may be issued on a project by project basis. Ann Bullis Name Signature 9 Date PLANNING DATA NAME:_ "coin M w DATE:_ Z/2 7/ -3 SITE ADDRESS: lsG o4-- 7S°' fl W, PLAN CHK#: 03 -53' PRO.ICT DESCRIPTION: Mewl;,,, hQfh(.e /'/.fie) l�,I,a r (44") 5k.A / I89 "/ -,A ,.I- I ble4 r REDUCED SITE PLAN PROVIDED?: Ce Uoo MAP PAGE: CORNER LOT: es /?No _ FLAG LOT: Yes / o ZONING: R-S - 7.- CRITICAL AREAS DETERMINATION #: i5 -1/ l 5 rw w �xy, �prf ��'`^` ✓ ti"L 0 Study Required: V- Zm- - iS —,, 4''"^ F f^f vr^'• —_� ❑ Waiver G,wca . aa, �a wa+« v/e fb*L V :L ? (,4, - i'U A cw' " 3 P- ❑ Conditional Waiver SEPA DETERMINATION: ❑ Fee r7 wH De..c �' ii1 M �"YAr., oL ° ^L(' t.+ r« M M*+c Mil 414,1 a441. ❑ Checklist ll/99 II❑ APO list w/ notarized form `1 (Needed for 500 cubic yards of grading, Shoreline Area- site within 200 ft. of Puget Sound or Lake Ballinger) V ❑ Exempt SETBACKS: (J/4- - n, 01—i, kPodrl Required Setbacks: Street: Left Side: Right Side: Rear: Actual Setbacks: " Street: Left Side: Right Side: Rear: Street map checked for additional setback required? (Yes / No / DNA) ❑ DETACHED STRUCTURES: X. ❑ ROCKERIES: n� "kk ❑ FENCES/TRELLISES: ❑ BAY WINDOWS / PROJECTING MODULATION: ❑ STAIRS / DECKS: C�"' P A-fjj " 4""t u, Pam PARKING: Required: 94 Actual: LOT ARFA- `YL '7SO LOT O �z Al,,, BUILDING HEIGHT: N/A Datum Point: Datum Elevation: Maximum Allowed: Actual Height: A.D.U. CREATED?: fWoj Yes) SUBDIVISION: JY +,c ► S �a WGZ ,r ram. tiA �n ate_ LEGAL NONCONFORMING LAND USE DETERMINATION ISSUED: Yes / o 6 9zo OTHER: "2Aa. -G V x — A—te a,,*- l k-a ;M ' oil i A^i4,1, (Kr 4L.' '- nnr OL LCo la�iu E -12-M ` V. i )J_1 /.•i.'!.. J% A • lU4-e A-e-, rei ^A,( wMC p. 1 %.a•I�(.G1-C. N/v`n.L (aLGAµs! .�- Mr [-ewl� W� Sic Ac a �.( L(L.VL(O/Je'K•.,r fu�ti. i.f /-Y GK Plan Review By: NewBPPlanningDataForm.DOC PLANNING DATA NAME: 'T1wt5& AlAn` $4 SITE ADDRESS: _15too 4- 75n DATE: 91XI/2-no ZONING: P-S- Za PLAN CHK#: 199 — 44 PROJECT DESCRIPTION:_ "OF- - Mc,1J.4wA4 _ Awa.- CORNER LOT Na (Yes/No) FLAG LOT As (Yes/No) SETBACKS: Required Setbacks: Front: 7 • Left Side: WV35' Right Side: I013s'. Rear: - Z5 Actual Setbacks: -� k-,K � ajjIv-i1,�� o,,n-r : 4-', Front: d ' i *' Left Side: I-T Right Side: Zr3, I „ Rear: 7V Street map checked for additional setback required? m - mit(Yes/No) LEGAL NONCONFORMING LAND USE DETERMINATION ISSUED N (Y/N) LOT COVERAGE: (AW1. j ZZ' 9� Maximum Allowed: 35h. Actual:23 a� 13,+S z. 13 °Z BUILDING HEIGHT: Maximum Allowed: 7-5' Actual Height: _ 7-5 ) Datum Point: -it n rL sm,L- 1. �J. r"., Datum Elevation: //6,. i3, A.D.U. CREATED?: fF cr�x�,, ��,r rsws�� a i 3+? sa:(� . ►^ ^�,� i,. a. !x-Ar>s••n/ �11,�a.,„ . n Slums l 9'/4 ytA,'- kw r-o, fa on:n. bw 9747- verK;on A-i A-w, SUBDIVISION: 5-9q- i 44 I ) ►„ ow„ ,� I r6Y f61 CRITICAL AREAS #: 95 -1 bl - 5a 2!4 ; �*y s�-Pq -, t44ti b �> oL sPN - ice � 7� -4 SEPA DETERMINATION: DNS Arynp'al r,, a,, Z� 197°J, SFn L, Q g , sale-/7a LOT AREA: Z 3. 4 sla OTHER: 5acw s�vc su�bvucc s�i�v q L� w�ti b�1v i� V- 7,�-35 'iku ror� a r+ 4 S,m��a $/iz, M •�h �o' oLw,r Plan Review By: OffleAKnniA-plandacdoc . CITY CCU? DRAINAGE .CALCULATIONS FOR: Aldridge Residence 16504 75th Place West Edmonds, .WA Project No. 9809 .21 PC �.�� 5 se, Y S. 44 1728RQp ISTE S SION��G EXPIRES 11M00 ?i C qc�mmoll ENGINEERING 111 MAIN STREET, SUITE 106 EDMONDS, WASHINGTON 98020 (425) 778 - 8500 These calculations delineate a hydrologic assessment for a proposed single family residence located at 16504 75`h Place West, Edmonds. The subject site, approximately 1.25 acres in size, is situated along the Puget Sound waterfront in the Meadowdale area of Edmonds. The site is bordered on the east by 75 h Place West, on the north and south by existing single family residences, and on the west by the Burlingtom Northem/Santa Fe (BNSF) railroad tracks. The site currently contains three buildings: a 1,200 sf dilapidated single family residence; a 1,125 sf dilapidated utility building; and a small storage shed. Existing site topography is steep to very steep with some evidence of past slides. The western 1/3 of the site is dominated by slopes in excess of 40% which extend down into the BNSF right-of-way. The topography of the site directs stormwater runoff westerly to the eastern side of the BNSF railroad tracks. An existing ditch in this location collects and conveys this runoff to culverts situated beneath the tracks, which subsequently discharge to Puget Sound. Stormwater runoff from the upland basin is intercepted by an existing ditch and storm drain system along.75`h Place West. Erosion control and site drainage facilities were designed to comply with the City of Edmonds Community Development Code Title 18 with the exception of on -site detention. Due to the close proximaty of the subject site to the Puget Sound, on=site detention necessary to reduce streambank erosion and/or to address inadequate downstream conveyance system capacity is not warranted for this development. Discussions with Trent Hudak, P.E. of BNSF regarding basin hydrology and conveyance systems beneath the BNSF railroad tracks to the Puget Sound in this area (see attached letter) confirm this assessment. In light of these conditions, undetained discharge from the development is proposed to be tightlined down the western slope to the existing BNSF railroad ditch ,l'li jli l.yyv 10:18 4257785536 CG ENGINEERING PAGE 02 C 4M ENGINEERING December 31, 1998 t:. ,.-. Trent A Hudak, P.E. Burlington Northern Santa Fe Railroad 2454 Occidental Ave South - Suite IA Seattle, WA 98134 Re: Aldridge Residence —16SO4 7Sth Place West Dear Trent: This letter is to confirm our recent conversation regarding stormwater runoff from the above referenced project and to provide documentation to the City of Edmonds indicating your concurrence with direct discharge from the proposed development to the east side of the Burlington Northern Santa Fe (BNSF) railroad tracks, During our conversation on 12/22/98 you indicated that you had reviewed our calculations and drawings submitted for the purpose of approving discharge from the project site to the east of the BNSF railroad tracks. In our calculations we delineated a 100 year post -developed un- detained peak runoff from the site of 0.44 cfs. In discussing the hydrology of the basin and. the existing downstream drainage system, we concurred that direct discharge from the site without detention would be acceptable for this project. Please sign and date below to acknowledge your acceptance of direct discharge from the site as discussed above and to indicate your approval of our revised detail (attached) for dispersion of stormwater along the east side of the subject tracks. Thank you for your time and consideration to this matter. Please feel free to call with anv questions or concerns. Sincerely, CG Engineering Jeff Haynes, P.E. a 14 * Street u 9llttaiaB, WA QM .off: 425.71e.M Project Manager Acknowledgment: 7-R - ff 5/94 signature date T�� dGl� �o•� s�Grrvha � ,E„ 9ii22Pi vrinted name and title .12/31,/1998 10:18 4257785536 CG ENGINEERING 14 is VP W � � W 9 lie O �6 Q� a � d a� i ;,i I N N PAGE 03 V / r /MN 190 • SRo>rcT' l 1 /2 1 MILE 1000 0 1000 2000 3000 4000 FEET Printed from TOPO! m1997 Wildflower Productions (www.topo.com) � ........ a �e � 50 N • •SOIL SURVEY OF SNOHOMISH COU PRosFc i sfrf- 1 OOOOFEET (Joins sheet 44) R � d.y : � Y�-': �cisi• ^��• a�+i�.v � i&,�Be'�atlf� [. •r 4 ` t '•��y:'•-� eYrr�} SS?� � d •S �� , (', • >'"'J�.�• __ � 'a • �`J r , .r , t 3 73 •1. r r +Y e f { k « �.��i ,, � � �'. 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', i ""F - �_� l't, f .� =11Ytt _!t�e�r-�i .� » .•�J ai#la.�' • `�'j'�' ...i �t ';tom'... �.` '32 `=17 L(- tQbai� (Joins sheet 57) TYPC "V AI-DA2wvv© ,EvEitFTT GARuTr cy, S,4NDY C-OA- VI $ 1 3/4 1/2 1/4 0 70 1 0.5 0 • �, ��. •� -.J r.' ;:ail` .1T:E!'• 'r�., �a: ' 1 , . , �:. y: , ... _ �,. ; .r.�•1 :l_ '.:1�: i'r:•..�. , � \ia r-h.'��1 • .1.T .t6y�c -� �). u`;t hf, lid• !t. r:� r�� J+'l�J'x"'i��=�:.. ........` N:-:�. �: _'y',�'T�`�j,....��_c.:.�a*�t� � .' �..ka .r ' _f'.\'i.y+�r.��;...�. -..... .-._.are.. •�.a`�:� �, - � n Sta'�.. `. .a%5 a s a 11RRTT �,�� ! Ste. '!� "�E v.��: 'l ��;� S►�- �w'-'1Y'�'l-R�•::i,.:__. , �.�: ••:r. _�. - _ T .•� STORMWATER MANAGEMENT MANUAL FOR THE PUGET SOUND BASIN Table III-1.6 Hydrologic Soil Groups fos Soils in the Puget Sound Basin Hydrologic Soil [Soil Hydrologic Soil Soil Type Group Type Group Agnew C Colter C Ahl B Custer ND Aits C Dabob Delphi Dick ND D ND Alderwood C Arents, Alderwooa is. Arena, Everett B Dian! D Ashoe B Dupont D Baldhrll B Earimont C Baraeston C Edgewick C Baumgard B Ed B Beausite B Elwell B Belfast C Esquattel B Bellingham D Everett A Bellingham variant C Everson D Boistfort B Galvin D Bow. D Getchell A Briscot D Giles B Buckley C Godfrey D Bunker B Greenwater A Cagey C Grove C Carisborg ND Harstine . C Casey ND Hartnit ND Cassolary C Hoh ND Cathcart B Hoko ND Centralia B Hoodsport ND Chehalis B Hoogdal C Chesaw A Hoypus ND Cinebar B Huel ND Clallam C Indianola ND Clayton B Jonas B Coastal beaches variable Jumps ND Kapowsin CID Kalaloe6 C Kanda C Rem D Kilchis C Republic B Kitsap C Riverwash variable Klaus ND Rober C Mono ND Saw C Lates C Salkum B Lebam B Sammamish D Vrmmi ND San Juan ND Lynnwood ND Scanumn D Lystair ND Schneider B Mal C Seattle D Manley B Sekiu ND Mashel B Semishmoo D Maytown C Shalcar D McKenna D Shano B McMurray ND Shelton C Melbourne B Si C Menzel ND Sinclair C Mixed Alluvial variable Skipopa D Molson B Skykomish B Mukilteo CID Snohopish ND Naff l B Snohomish D Nargar A Solduc B National ND Solleks ND Neilton A Spam D III-1-9 FEBRUARY, 1992 STORMWATER MANAGEMENT MANUAL FOR THE PUGET SOUND BASIN Table III-1.3 SCS Western Washington Runoff Curve Numbers (Published by SCS in 1982) Runoff curve numbers for selected agricultural, suburban and urban land use for Tvne lA rainfall distribution. 24-hour storm duration. LAND USE DESCRIPTION CURVE NUMBERS BY HYDROLOGIC SOIL GROUP A B C I D Cultivated land(1): •winter condition 86 91 94 95 Mountain open areas: low growing brush & grasslands 74 82 89 92 Meadow or pasture: 65 78 85 89 Wood or forest land: undisturbed 42 64 76 81 86 94 Wood or forest land: young second growth or brush 55 72 81 Orchard: with cover crop 81 88 92 Open spaces, lawns, parks, golf courses, cemeteries, landscaping. 68 80 86 90 Good condition: grass cover on t75% of the area 77 85 90 * 92 Fair condition: grass cover on 50-75% of the area Gravel roads & parking lots: 76 85 89 91 Dirt roads & parking lots: 72 82 87 89 Impervious surfaces, pavement, roofs etc. 98 98 98 98 Open water bodies: lakes, wetlands, ponds etc. 100 100 100 100 Single family residential(2): Dwelling Unit/Gross Acre %Impervious(3) Separate curve number 1.0 DU/GA 15 shall be selected for 1.5 DU/GA 20 pervious & impervious 2.0 DU/GA 25 portions of the site 2.5 DU/GA 30 or basin 3.0 DU/GA 34 3.5 DU/GA 38 4.0 DU/GA 42 4.5 DU/GA 46 5.0 DU/GA 48 5.5 DU/GA 50 6.0 DU/GA 52 6.5 DU/GA 54 7.0 DU/GA 56 PUD's, condos, apartments, %impervious commercial businesses & must be industrial areas computed (1) For a more detailed description of agricultural land use curve numbers refer to National Engineering Handbook, Sec. 4, Hydrology, Chapter 9, August 1972. (2) Assumes roof and driveway runoff is directed into street/storm system. (3) The remaining pervious areas (lawn) are considered to be in good condition for these curve numbers. III-1-12 FEBRUARY, 1992 4kyfL STORMWATER MANAGEMENT MANUAL FOR THE PUGET SOUND.BASIN 124 123 122 121 49 _. 45 .480 EL t c lY ds 40 I 45 PRE sr�T o �:, � � C S r,� ► �. 55 _ 40� "i HA R OR .PORT S7ANLE 6t Go 70 .. i �5 6085 \ 35 30 % I 10 ON, 10 .75 _ %� T 5 6 � / I 0 302 'S' ' � �� ( 55 48 75 3 1 = =u tt 80 5 45 t o . I 8. 35 4@ (1 . , I )��1 so( 4 71 i `!eta • A 6 E 1 E�� W i 55t � Y ^�� ' I� •Y Y� vu�s _ �� 40 IADAM' 95 WASHINGTON ; '40 - tzK`l 100 PLl EN E 10 '0 10 20 30 40 Op 7 1 - ^---� MILES 40 /I04635 .... _� Figure 30 I NOAA ATLAS 2, Volume IX 45 50 55 60 65 ` Prepared by U.S. Department of Commerce ISOPLUVIALS F 100-YR 24-HR PRECIPITgTION National oceanic and Atmospheric Ak!ministration IN TENTHS OF N INCH National Weather Servit:e, office of Hydrology Prepared for U.S. Department of AJricukure, — 'Sail Conservation Service, Engineering Division 124 123 122 121 III-1-46 FEBRUARY, 1992 100yr.txt KING COUNTY DEPARTMENT OF PUBLIC WORKS Surface Water Management Division HYDROGRAPH PROGRAMS Version 4.21B 1 - INFO ON THIS PROGRAM 2 - SBUHYD 3 - MODIFIED SBUHYD 4 - ROUTE 5 - ROUTE2 6 - ADDHYD 7 - BASEFLOW 8 - PLOTHYD 9 - DATA 10 - RDFAC 11 - RETURN TO DOS ENTER OPTION: SBUH/SCS METHOD FOR COMPUTING RUNOFF HYDROGRAPH STORM OPTIONS: 1 - S.C.S. TYPE-lA 2 - 7-DAY DESIGN STORM 3 - STORM DATA FILE SPECIFY STORM OPTION: S.C.S. TYPE-lA RAINFALL DISTRIBUTION ENTER: FREQ(YEAR), DURATION(HOUR), PRECIP(INCHES) ---------------------------------------------------------------------- ******************** S.C.S. TYPE-lA DISTRIBUTION ******************** ********* 100-YEAR 24-HOUR STORM **** 3.00" TOTAL PRECIP. ********* ---------------------------------------------------------------------- ENTER: A(PERV), CN(PERV), A(IMPERV), CN(IMPERV), TC FOR BASIN NO. 1 DATA PRINT-OUT: AREA(ACRES) PERVIOUS IMPERVIOUS TC(MINUTES) A CN A CN .7 .4 86.0 .2 98.0 5.0 E -- A SSOA10 0 PEAK-Q(CFS) T-PEAK(HRS) VOL(CU-FT) 38 7.67 5006 ENTER (d:](path]filename[.ext] FOR STORAGE OF COMPUTED HYDROGRAPH: SPECIFY: C - CONTINUE, N - NEWSTORM, P - PRINT, S - STOP Page 1 Orz/G�N/'►c. c�cc��,�rlJ•vs 5„gv,-� TR�N�N�o�K CoNsr-) wf�� ,z 4AA64A R F S / Dr3N c,C �✓/ Ma �2 /M PkR V /o S S 0iZ Fi4cA CORPORATE OFFICE 911 Fifth Avenue, Suite 100 Kirkland, Washington 98033 (206) 827-7701 FAX (206) 827-5424 BAINBRIDGE ISLAND OFFICE 179 Madrone Lane North Bainbridge Island, WA 98110 (206)780-9370 FAX (206) 780-9438 • /��o�f � 94 k1 SUBSURFACE EXPLORATION, GEOLOGIC HAZARDS AND PRELIMINARY GEOTECHNICAL ENGINEERING REPORT ALDRIDGE SHORT PLAT EDMONDS, WASHINGTON PREPARED FOR Ms. Theresa Aldridge PROJECT NO. G97224A OCTOBER 1997 ASSOCIATED EARTH SCIENCES, INC 4, SUBSURFACE EXPLORATION, GEOLOGIC HAZARDS AND PRELIMINARY GEOTECHNICAL ENGINEERING REPORT ALDRIDGE SHORT PLAT 15604 75"' PLACE WEST EDMONDS, WASHINGTON October 24, 1997 Project No. G97224A I. PROJECT AND SITE CONDITIONS 1.0 INTRODUCTION This report presents the results of our subsurface exploration, geologic hazards and preliminary geotechnical engineering study for the proposed residential 2-lot plat, located at 15604 75" Place West, Edmonds, Washington. Our study was performed with the understanding that the 1 1/ acre property is proposed to be subdivided into 2 residential lots. The locations of existing and proposed structures and the approximate location of the subsurface explorations completed for this study are presented on the Site and Exploration Plan, Figure 1. In the event that any changes in the nature, design, or location of the structures are planned, the conclusions and recommendations contained in this report should be reviewed and modified, or verified, as necessary. 1.1 Purpose and Scope The purpose of this study was to provide subsurface soil and shallow ground water data to be utilized in the preliminary design and development of the subject residential project. This report is intended to comply with the City of Edmonds Geotechnical Report Guidelines for sites within the Meadowdale area (ECDC 19.05.030B). Our field study included the excavation of four exploration pits, three exploration borings, the installation of two slope inclinometers, and performing geologic studies to assess the type, thickness, distribution and physical properties of the subsurface sediments. Geotechnical engineering studies were also conducted to determine seismic and landslide hazard considerations, the type of suitable foundation, allowable foundation soil bearing capacities, anticipated foundation settlements, floor support considerations, utility connection considerations, lateral wall pressures, and drainage considerations. We also reviewed a geotechnical report prepared by Terra Associates, Inc. dated July 28, 1990 conducted for the property to the north of the subject property. This report summarizes our recent field work and offers development recommendations based on our present understanding of the project. Also, this report is preliminary and subject to modification due to ongoing slope monitoring and potential changes in development plans. ' 1.2 Authorization Written authorization to proceed with this study was granted by Ms. Theresa Aldridge. Our study was accomplished in general accordance with our proposal dated August 18, 1997. This report has been prepared for the exclusive use of Theresa Aldridge, and her agents, for specific application to this project. Within the limitations of scope, schedule and budget, our services have been performed in accordance with generally accepted geotechnical engineering and engineering geology practices in effect in this area at the time our report was prepared. No other warranty, expressed or implied is made. Our observations, findings, and conclusions are a means to identify or reduce inherent risks to the owner. 2.0 SITE AND PROJECT DESCRIPTION The subject property is located at 15604 75`h Place West. The approximately 260 foot north - south by 195 foot east -west rectangular -shaped property was bordered on the west by the f Burlington Northern Railroad, on the east by 75' Place West, and on the north and south by single family homes. Puget Sound was located just west of the Burlington Northern Railroad. The railroad tracks lie approximately 40 feet west of the western property line. The subject property sloped down from 75"' Place West to the railroad tracks. Three existing structures were located on a gently sloping bench with steep slopes located on the west and to the east. To the west, a steep, approximately 55 percent slope, 40 feet tall, sloped down towards the railroad tracks. Many of the taller trees on this steep western slope were tilted downslope. To the east, a steep, 65 to 75 percent slope rose up towards 75`h Place West. The slope to the east varied from a few feet high at the south end to 32 feet at the north. Existing structures on the property consisted of a dilapidated house, utility building, and storage shed. The house was a wood -frame, one-story structure with daylight basement and was located on the north side of the property. The utility building was a wood -frame, two- story structure with a crawlspace and was located on the south side of the property. The storage shed was located approximately 45 feet west of the utility building. The existing home revealed evidence of previous subsurface soil movement. The basement retaining and foundation walls were cracked and out of plumb. In addition, window frames were askew and the home was generally tilted to the west approximately 6 inches. Preliminary plans are to demolish the existing structures and construct two new homes. The new homes are to be located near the existing buildings. New construction will consist of two- story wood -frame homes with attached garages. Daylight basements and/or retaining walls are ;.a possible. Vegetation, within and surrounding the proposed building sites consisted mostly of blackberry j vines with a few deciduous trees. Utilities to the existing house consisted of sewer and overhead power. The electrical power line to the house was observed to be under tension most likely due to downslope movement of the house. A sewer pump vault was located near the southeast corner of the house. The location of a water supply was not determined. However, T. 1 2 according to a nearby neighbor, Norm Nelson, an abandoned water well was located near, or possibly beneath, the existing house. 2.1 Back rg ound The Meadowdale area, including the subject property, has been identified as an earth subsidence/landslide area. The main Meadowdale landslide likely occurred several thousand years ago. According to Terra Associates, Inc.'s report and conversations with a nearby homeowner, parts of the original slide have more recently moved during the winters of 1946- 47, 1955-56, and during the 1960s and 1970s. According to'Norm Nelson, slope movement in the winter of 1955-56 caused damage to the existing house. On the subject property there was evidence of subsurface movement that may have occurred as recently as this last winter. This evidence consisted of tension cracks and scarps which were not heavily eroded or overgrown 'with vegetation. Several previous, regional -scale geotechnical studies have been completed by others to evaluate the landslide hazard potential within the Meadowdale area. In 1979, Roger Lowe Associates, Inc. estimated landslide failure probabilities on a map of the Meadowdale area. At the time of Lowe's report, Lowe estimated that the subject property had a 90 percent chance of landslide movement during a 25-year period. In 1980 through 1985, sanitary sewer, storm sewer, and ground water interceptor drains were installed within landslide areas based on recommendations from Lowe's report. In 1985, GeoEngineers, Inc. revised Lowe's landslide probabilities based on the installation of ground water control improvements. For the subject property, the probability of a landslide occurring in a 25-year period was reduced by GeoEngineers from 90 percent to 30 percent. 3.0 SUBSURFACE EXPLORATION Our field study included excavating a series of exploration pits, drilling exploration borings and the installation of two slope inclinometers to gain subsurface information about the site. The exploration pits were excavated on August 18, 1997 and the exploration borings with slope inclinometers were completed on September 9 and 10, 1997. Our field work was conducted during an extended period of dry weather. The various types of sediments, as well as the depths where characteristics of the sediments changed, are indicated on the exploration logs presented in the Appendix. The depths indicated on the logs where conditions changed may represent gradational variations between sediment types in the field. Our explorations were approximately located in the field by measuring from known site features shown on a site plan with topographic information prepared by Cramer Northwest, Inc. dated September 4, 'i 1997. The preliminary conclusions and recommendations presented in this report are based on the 4 exploration pits and 3 exploration borings completed for this study. The number, location, and depth- of the explorations/borings were completed within site and budgetary constraints. Because of the nature of exploratory work below ground, extrapolation of subsurface conditions between and beyond field explorations is necessary. It should be noted that 3 'differing subsurface conditions may sometimes be present due to the random nature of deposition and the alteration of topography by past grading, filling; and landsliding. The nature and extent of any variations between the field explorations may not become fully evident until construction. If variations are observed at that time, as new information becomes available, it may be necessary to re-evaluate specific recommendations in this report and make appropriate changes. This report is preliminary and subject to modification based on future monitoring of the slope inclinometers installed on the property. 3.1 Exploration Pits Exploration pits were excavated with a track -mounted Case 9010B 30,000-pound excavator to a depth from 15 to 18 feet below present surface grade. The pits permitted direct, visual observation of subsurface conditions. Materials encountered in the exploration pits were studied and classified in the field by a geotechnical engineer from our firm. All exploration pits were backfilled immediately after examination and logging. Selected samples were then transported to our laboratory for further visual classification and testing, as necessary. 3.2 Exploration Borings The exploration borings were completed by advancing a 4'/a inch inside -diameter, hollow - stein auger using a track -mounted drill rig. During the drilling process, samples were obtained at generally 2.5 or 5.0-foot depth intervals. The borings were continuously observed and logged by a geotechnical engineer from our firm. The exploration logs presented in the Appendix are based on the field logs, drilling action, and inspection of the samples secured. Disturbed but representative samples were obtained by using the Standard Penetration Test procedure in accordance with ASTM:D-1586. This test and. sampling method consists of driving a standard 2 inch outside -diameter, split barrel sampler a distance of 18 inches into the soil with a 140 pound hammer free -falling a distance of 30 inches. The number of blows for each 6 inch interval is recorded and the number of blows required to drive the sampler the final 12 inches is known as the Standard Penetration Resistance ("N") or blow count. If a total of 50 are recorded within one 6-inch interval, the blow comet is recorded as 50 blows for the number of inches of penetration. The resistance, or N-value, provides a measure of the relative density of granular soils or the relative consistency of cohesive soils; these values are plotted on the attached boring logs. 3.3 Slope Inclinometers Two slope inclinometers were installed on the property to monitor potential slope movement. Slope inclinometer 1 (SI-1) was located within EB-1 and SI-2 was located within EB-3. The slope inclinometer casing consists of 2 inch diameter PVC pipe that has 4 vertical grooves. An instrument is periodically lowered down the casing via the groove tracks to measure the casing profile. These measurements are taken to determine the magnitude of movement over time. -. 4 4.0 SUBSURFACE CONDITIONS Subsurface conditions on the parcel were inferred from the field explorations accomplished for this study, visual reconnaissance of the site and review of applicable geologic literature. As shown on the exploration logs, the exploration holes generally encountered fill and colluvium materials overlying natural silt/clay and sand deposits. The following section presents more detailed subsurface information organized from the upper (youngest) to the lower (oldest) sediment types. 4.1 Stratigraphy Fill Fill soils (those not naturally placed) were encountered in all four exploration pits and in all three exploration borings. The fill was approximately 4 feet deep in EP-2, EB-2, and E13-3. In EP-4 and EB-1 the fill was estimated to be approximately 8 to 10 feet deep, respectively. Disturbed/fill soils were observed to a depth of 3 feet in EP-1 and. EP-3. As noted on the exploration logs, the fill varied in material properties. Within EP-2, the fill generally consisted of loose, moist, brown, sand. and gravel. In EP-4 the fill consisted of loose, dry, dark brown, fine sand with gravel, roots, and chunks of asphalt. In EB-1 and EB-2 fill soils consisted of loose, damp, reddish -brown, sand with varying amounts of gravel. The fill soils appeared to vary in both quality and depth across the site. Since the quality, thickness and compaction of the fill materials are variable, the fill is unsuitable for foundation support. Possession Drift Natural soils beneath the fill materials consisted, for the most part, of stiff, moist, bluish -gray, clay or silt and occasional lenses of silty fine sand. These sediments were encountered in our exploration pits from depths ranging from 3 feet (EP-1) to 12 feet (EP-3) beneath present surface grade and extended below the termination depth. In our exploration borings these sediments were first encountered from approximately 4 feet (EB-2 and EB-3) to 11 feet (EB-1) below present surface grade. These sediments extended to 321/2 feet, 27 feet, and 17 feet below surface grade in EB-1, EB-2, and EB-3, respectively. The stiff bluish -clay sediments have been interpreted as Possession Drift sediments. These Possession Drift sediments were deposited in a glacial lake environment and subsequently overridden by multiple glaciations. Double Bluff Drift Beneath the fine-grained Possession Drift sediments, our three exploration borings terminated in very dense, moist, light brown, fine sand. The termination depth of our borings was at 36'/2 feet below present surface grade. These fine sand sediments have been interpreted as Double z Bluff Drift glacial deposits. a 5 i 4.2 Hydrology Ground water was not encountered in any of our subsurface explorations. During wetter times of the year we expect some ground water seepage from perched zones on top of the Possession clay sediments and within sand lenses. In the Puget Sound Basin, the Possession Drift sediments are very fine-grained and in a compact condition which has resulted in a near impermeable barrier to the vertical movement of ground water. Minor horizontal movement of ground water can be expected within thin sand lenses. No seepages were observed daylighting at the toe of the slopes located on the east and west sides of the proposed home locations at the time of our explorations. R October 24, 1997 Project No. G97224A II. GEOLOGIC HAZARDS AND MITIGATIONS The following discussion of geologic hazards is based on the geologic, slope and ground/surface water conditions as observed and discussed herein. The discussion will be limited to seismic, landslides, and erosion. 5.0 SEISMIC HAZARDS AND RECOMMENDED MITIGATION Earthquakes occur in the Puget Lowland with great regularity. Tile vast majority of these events are small and are usually not felt by people. However, large earthquakes do occur as evidenced by the 1949, 7.2 magnitude event and the 1965, 6.5 magnitude event. The 1949 earthquake is the largest in this area during recorded history. More recently, the Puget Lowland experienced a moderate 5.4 magnitude event in the spring of 1996 and a 4.9 magnitude event in the spring of 1997. Evaluations of earthquake return rates indicate that an earthquake of the magnitude between 5.5 and 6.0 likely will occur within the next 8 to 12 years. The subject property is located near several identified signficant fault zones. The north- northwest trending South Whidbey Island/Lake Alice fault has been mapped through the Meadowdale area. Recently, two north -south trending faults have been tentatively mapped beneath the waters of Puget Sound and within 10 miles southwest of the subject site. The Whidbey Island fault zone is interpreted to represent a significant boundary between two major crustal blocks. The fault originated as a right lateral strike -slip fault but vertical offset has also been identified. No recurrence interval has been conclusively determined for movement along the Whidbey Island fault, but is estimated to be thousands of years (Pratt, 1995). Published reports of the north -south trending faults beneath Puget Sound have not been completed at the time of this report. However, it is preliminarily estimated that the recurrence interval for the faults is thousands of years. Generally, there are 4 types of potential geologic hazards associated with large seismic events: 1) surficial ground rupture; 2) seismically induced landslides; 3) liquefaction; and 4) ground motion. The potential for each of these hazards to adversely impact the proposed project is discussed below. 5.1 Surficial Ground Rupture Generally, the largest earthquakes, which have occurred in the Puget Sound/Seattle area, are sub -crustal events with epicenters ranging from 50 to 70 kilometers in depth. Therefore, it is 17 • • our opinion, based on existing geologic data, that the risk of surface rupture impacting the proposed project is low and no specific mitigations are recommended. 5.2 Seismically Induced Landslides The steep slope located on the east side of the proposed home locations likely consists of shallow surficial fill soils used for the road grade, overlying natural stiff silt/clay sediments. As previously mentioned, no seepages were observed at the toe of the slope. Various areas of the slope were evaluated using a soils probe. Probing with a standard soil probe indicated that stiff sediments were present at shallow depths (approximately one foot) on the slope. Based on probing, geologic literature, and our reconnaissance of the area, it is our opinion that the core of the slope is comprised of consolidated, natural sediments. Due to the soil density and lack of adverse ground water conditions, the potential for a seismically induced landslide of the core of this slope is interpreted to be low. Mitigation for. this slope will include leaving mature, natural vegetation intact, preventing runoff from discharging onto the slope, and possible enhancement of native ground cover plants to reduce the potential for surface erosion. The steep slope on the west side of the proposed home locations consisted of Possession Drift sediments (clay) as observed on the slope surface. Near the top of the slope at the northwest corner of the property was a 2 to 3 foot tall vertical landslide scarp. The ground below the scarp likely shifted last winter based on the lack of erosion and overgrowth of the scarp face. Another shallow scarp was identified near the existing shed. This scarp appeared older, was overgrown and the vertical offset of the ground surface was a few inches. The trunks of several trees on the slope were observed to be tilted slightly downslope indicating ongoing slope movement. No seepages were observed at the toe of the slope. Due to the history and recent evidence of subsurface soil movement on the property, the steep slope to the west of the proposed home locations is interpreted to have a moderate to high potential for a seismically induced landslides. Landslide mitigations are presented in Section 6.0, Landslide Hazards and Mitigation. 5.3 Liquefaction Liquefaction is a condition where loose, saturated, fine-grained soils lose shear strength when subjected to high intensity, cyclic loads of very short duration, such as occur during earthquakes. The resulting reduction in strength can cause differential foundation settlements and slope failures. Loose, saturated, fine-grained sands, which lack cohesion and cannot z dissipate the buildup of pore water pressure, are most susceptible to liquefaction. Based on our review of the samples obtained from our explorations, it is our opinion that the encountered stratigraphy has a very fine-grain size, cohesive (clay) sediments that have been glacially consolidated. The sediment type is not prone to liquefaction. Therefore, there is a low potential for soil liquefaction and no mitigations are recommended. N. 4. 5.4 Ground Motion • • Based on the stratigraphy and visual reconnaissance of the site, it is our opinion that any earthquake damage to the proposed structures founded on a suitable bearing strata, and following the recommended setback recommendations, would be caused by the intensity and acceleration associated with the event and not any of the above discussed impacts. - Structural design of the building should follow UBC standards for Seismic Zone 3. 6.0 LANDSLIDE HAZARDS AND MITIGATION The potential landslide risk can be divided into two depth categories; shallow and deep. The potential shallow (approximately 8 feet thick) landslide risk includes the fill soils on top of the Possession Drift (clay) sediments. Based on discussions with Norm Nelson and on our subsurface investigation, the existing house was likely damaged from a shallow landslide. In addition, the presence of landslide scarps, which appear to be recent, indicate that there has been recent shallow landslide soil movement. The potential deep, landslide risk has been identified at the Possession (clay) and Double Bluff (fine sand) contact. This deeper slide surface was identified at depths of approximately 31 feet, 26 feet, and 16 feet in EB-1, EB-2, and EB-3, respectively. Currently, it is not known whether the deep-seated slide is active, has been active in the recent past, or is ancient. Slope inclinometers were installed to assist in the evaluation of whether the deep-seated slide plane is currently active. On a preliminary basis, we concur with the assessment by GeoEngineers that the subject property has a 30 percent probability of ground failure within a 25-year period. The risk for shallow landslides can be reduced by several methods. Currently the roof downspouts from existing structures discharge onto soft/loose fill soils. In addition, the soft/loose soils surrounding the house have open tension . cracks, which readily permit the infiltration of surface runoff, exacerbating the landslide potential. The risk of shallow landslides can be partially mitigated through the control of storm water runoff as described in Section 15.0, Drainage Considerations. Portions of the property can be graded to further reduce the potential for shallow slope movement. The buffer area between the top of the western slope and the proposed homes can be terraced. Terracing the moderate slope by the removal of 3 to 6 feet of soil would reduce the potential of shallow soil movement by reducing the weight of excess fill soil at the top of the slope. At no time should fill be pushed over or placed near the top of slopes. Buildings should be set back from the toe of the eastern slope by 20 feet. Preliminary top of slope setbacks of 35 feet and 25 feet are recommended for the western slope and the southern slope, respectively. These slope setbacks are subject to modification based on periodic monitoring of the property through the winter. Associated Earth Sciences, Inc. (AESI) should review grading plans to address slope stability concerns. Through the proper management of storm water runoff and proper grading of the property, the potential risk of shallow subsurface movement can be reduced but it must be understood that some risk will always remain. This risk can be quantified by slope stability modeling during the design optimization phase of the project. 4 E Significant grading of the property should be limited to dryer times of the year (May 1 to October 1). Since our explorations were completed during the dry sutmmer months, an accurate assessment of potential ground water conditions was not possible. If our continued monitoring reveals slope movement, seepage/spring activity, or other drainage concerns, it is recommended that additional subsurface work (exploration pits or borings) be conducted during wetter times of the year to assess ground water conditions and their potential impacts to slope stability. 7.0 EROSION HAZARDS AND MITIGATION When disturbed, the encountered surficial sediments, as well as sediments at depth, possess a moderate potential for erosion, even on gentle to moderate sloping areas, when subjected to concentrated flows. Therefore, storm water runoff should be collected, routed and discharged through a suitable, City approved storm water system. Uncontrolled discharge from impermeable surfaces should not be allowed to flow across or infiltrate into the site sediments. It is our understanding that the existing structures may be demolished during the fall or winter of 1997 with new construction to occur at a later date. Erosion control measures for the demolition phase of work should consist of,the following: 1. Placement of 2 inch or larger crushed rock for construction equipment access road improvements. 2. Once existing structures have been demolished, all exposed ground surfaces should be hydroseeded and mulched with a suitable seed/mulch erosion control mixture. 3. All work should be confined to the immediate vicinity of the structures and access road. 4. Additional measures should be employed as necessary to prevent off -site sediment transport. Once new development activities are begun, to mitigate erosion and off -site sediment transport, we recommend the following measures: A silt fence should be constructed at the lower portion of the property to intercept any sediment eroded during the construction phases of the project. 2. The outlets from detention/retention facilities on the property should be designed to prevent direct flow over unprotected slopes. This can be accomplished by tightlining the outlets down to the toe of the western slope. 3. All disturbed areas should be re -vegetated or landscaped as soon as possible. 10 J 4. If construction occurs after October 1 and before April 1, exposed ground should be maintained with a mulch cover. 5. Surface runoff must not be directed onto or above the steeply sloping areas. All devices used to collect surface discharge should be directed into a tightlined system., which discharges away from slope areas. Uncontrolled discharge on slope areas will promote erosion and slope instability. 6. Temporary erosion and sedimentation facilities must be maintained and improved as necessary to control runoff and off -site sediment transport. 11 ,i October 24, 1997 Project No. G97224A III. PRELIMINARY DESIGN RECOMMENDATIONS 8.0 INTRODUCTION Our exploration indicates that, from a geotechnical standpoint, the parcel is suitable for the proposed development with the understanding and acceptance that some risk of earth movement will always be present. The foundation -bearing stratum is relatively deep, approximately 9 feet below present surface grade. Due to the history of landslide movement and a thick sequence of landslide, fill, or disturbed soils, we recommend the installation of a deep foundation system (piles) for the new structures. A pile foundation is also recommended for support of garages and slab -on -grade floors. Pavements for driveways can be supported on compacted existing fill or structural fill that is placed atop compacted existing fill. Recommendations for preparation of driveway subgrades are discussed in the Site Preparation section of this report. Our foundation recommendations are based on the preliminarily interpretation that the deep- seated landslide potential is inactive. Therefore, the recommendations in this report are preliminary and subject to modification based on results of future monitoring of the site. A pile foundation will not prevent damage from a deep-seated landslide. -` The conclusions and recommendations presented in this report are offered as a means to identify and reduce risks associated with steep slopes, erosion and seismic hazards. Elimination of risks from geologic hazards, as identified on this site, are not possible. It should be understood that our recommendations are not meant to fully mitigate against future earth movement, but will provide vertical foundation support only, without increasing the risks of slope movement. Development of the site using any of the recommendations presented in this report may only proceed if the owner accepts full responsibility for any damage in the event of slope movement. 9.0 SITE PREPARATION To mitigate the potential shallow landslide hazard we recommend that within critical landscape areas, the top 4 to 6 feet of loose fill soils should be removed. Critical landscape areas are those areas adjacent to steep slopes, which may have an increased potential for slope failure. These critical landscape areas are within 30 feet of the top of the westerly slope. The landscape areas can be terraced in order to remove loose fill soils (overburden). The removal of loose soils is intended to reduce the risk of shallow landslide potential. Slope movement in these - critical landscape areas may not directly impact the proposed residences, but would impact the buffer/setback zone between the houses and slope. Grading plans for these areas should be reviewed and approved by our office prior to construction. 1W • 0 Site preparation of planned building and driveway areas should include removal of all trees, brush, debris and any other deleterious material.. Additionally, for driveway areas the upper organic topsoil should be removed and the remaining roots grubbed. Areas where loose surficial soils exist due to grubbing operations should be considered as fill to the depth of disturbance and treated as subsequently recommended for structural fill placement. Any buried utilities should .be removed or relocated if they are under building areas. The resulting depressions should be backfilled with structural fill as discussed under the Structural Fill section. The soils at the site contain a high percentage of fine-grained material that makes them moisture -sensitive and subject to softening and disturbance when wet. We therefore recommend that earthwork operations should be performed during dry weather periods. 10.0 STRUCTURAL FILL There is a possibility that structural fill will be necessary to fill voids created by the removal of existing utilities or to establish desired grades for driveways. Under no circumstances should fill be placed on or near the steep western slope. All references to structural fill in this report refer to subgrade preparation, fill type, placement and compaction of materials as discussed in this section. If a percentage of compaction is specified under another section of this report, the value given in that section should be used. After the exposed ground is recornpacted and approved, structural fill should be placed to attain desired grades. Structural fill is defined as non -organic soil, acceptable to the geotechnical engineer, placed in maximum 8 inch loose lifts, with each lift being compacted to at least 95 percent of the modified Proctor maximum density (ASTM:D-1557). The top of the compacted fill should extend horizontally outward a minimum distance of 3 feet beyond pavement edges or building foundations before sloping down at an angle of 2H:1V (Horizontal: Vertical). The contractor should note that any proposed fill soils must be evaluated, approved and laboratory tested prior to their use in fills. This would require that we have a sample of the material 48 hours in advance to perform a Proctor test and determine its field compaction standard. Soils in which the amount of fine-grained material (smaller than No. 200 sieve) is greater than approximately 5 percent (measured on the minus No. 4 sieve size) should be considered moisture -sensitive. Use of moisture -sensitive soil in structural fills should be limited to favorable dry weather and dry subgrade conditions. The near -surface, on -site soils generally contained significant amounts of silt and are considered moisture -sensitive. At the time of our field work, the on -site, near -surface soils, were too wet to compact as structural fill. Construction equipment traversing the site when the soils are wet can cause considerable disturbance. If fill is placed during wet weather, or if proper compaction cannot be obtained, a select fill material consisting of a clean, free -draining gravel and/or sand should be used. 13 • • ' Free -draining fill consists of non -organic soil with the amount of fine-grained material limited to 5 percent by weight when treasured on the minus No. 4 sieve fraction. A representative from our firm should inspect the stripped subgrade and be present during placement of structural fill to observe the work and perform a representative number of in - place density tests. In this way, the adequacy of the earthwork may be evaluated as filling progresses and any problem areas may be corrected at that time. It is important to understand that taking random compaction tests on a part-time basis will not assure uniformity or acceptable performance of a fill. 11.0 FOUNDATION RECOMMENDATIONS As discussed in the first half of this report, the proposed building areas are underlain by fill and soft/loose soils, which are up to 9 feet thick. The depth of these sediments and their soft/loose condition would. likely result in excessive total and differential settlement of a conventional, shallow foundation constructed on or within this material. Extended spread footings founded on stiff clay sediments were also considered. However, in our opinion since the subject site has a history of soil movement, a pile foundation system would offer the most resistance to potential soil settlement and shallow earth movement. 11.1 Pile Foundations - Augercast Piles Cast -in -place concrete piles (augercast) are recommended for foundation support. We recommend that the placement of all piles be accomplished by a contractor experienced in their installation. We estimate pile lengths will be on the order of 17 to 20 feet for a 16 inch diameter pile with an allowable 10 ton vertical capacity, and an embedment of 8 feet into the bearing strata. Pile length estimates are relative to site grades at the time of our exploration and should be adjusted accordingly if the site is graded prior to pile installation. Pile lengths will be deeper at higher elevations on the property. Allowable design loads may be increased by one-third for short-term wind or seismic loading. Anticipated settlements of augercast pile -supported structures will generally be less than one half inch. 11.1.1 Lateral Pile Capacity The recommended allowable lateral capacity of 16 inch diameter augercast piles (applied at the pile top), assuming a fixed head condition, is 6.5 tons each. The lateral capacities above were determined assuming 0.5 inch of deflection at the pile top with the pile tops fixed to prevent rotation. A factor of safety of 2 was applied to the allowable horizontal lateral capacity. r For a -17 foot deep pile, the depth to fixity (maximum moment) has been calculated to be about 10 feet. Moment reinforcement should extend the full pile length. 14 11.1.2 Pile Inspections The actual total length of each pile may be adjusted in the field based on required capacity and conditions encountered during drilling. Since completion of the piles takes place below ground, the judgment and experience of the geotechnical engineer or his field representative must be used as a basis for determining the required penetration and acceptability of each pile. Consequently, use of the presented pile capacities in the design requires that all piles be inspected by a qualified representative from our firm who can interpret and collect the installation data and observe the contractors operations. The geotechnical engineer, acting as the owner's field representative, would determine the required lengths of the piles and keep records of pertinent installation data. A final summary report would then be distributed, following completion of pile installation. 12.0 FLOOR SUPPORT Floors may be either erawlspace, slab -on -grade, or structural (pile supported). For crawlspace, the. soil subgrade should be covered by a plastic moisture barrier. For slab -on - grade or pile supported, the soil subgrade must consist of stiff natural sediments or compacted structural fill as necessary to establish grades. Once the soil subgrade has been prepared to the desired grade and to the satisfaction of the geotechnical engineer, the floor should be cast atop a minimum of 4 inches of pea gravel to act as a capillary break. The pea gravel should then be covered by a plastic moisture barrier. A 2 inch layer of sand may then be placed atop the moisture barrier to aid in the finishing and curing of concrete and to protect the integrity of the plastic membrane: 13.0 UTILITY CONNECTIONS Due to the soft/loose nature of the near -surface soils underlying the site, flexible connections between all utilities and the residences are recommended. These connectors should allow up to 6 inches of ground movement. 14.0 LATERAL WALL PRESSURES Currently, retaining walls are not plaiuied. However, if retaining walls are to be used, the following considerations should apply. All backfill behind walls or around foundation units should be placed as per our reconumendations for structural fill and as described in this section of the report. Horizontally backfilled walls which are free to yield laterally at least 0.1 percent of their height, may be designed using an equivalent fluid equal to 40 pounds per cubic foot (pcf). Fully restrained, horizontally backfilled rigid walls which cannot yield should be designed for an equivalent fluid of 60 pcf. Surcharges from adjacent footings, heavy construction equipment, floor loads, or sloping ground must be added to the above values. 15 ' The lateral pressures presented above are based on the conditions of a uniform horizontal backfill consisting of imported sand and gravel compacted to 90 percent of ASTM:D-1557 with a 12 inch horizontal blanket drain of washed drain rock immediately adjacent to the wall. Achieving a minimum 90 percent of AS'FM:D-1557 compaction using on -site natural silty clay soils may be difficult. A higher degree of compaction is not recommended as this will increase the pressure acting on the wall. A lower compaction may result in settlement behind the wall. It is therefore recommended that wall backfill consist of imported sand and gravel. 14.1 Passive Resistance and Friction Factors Retaining wall footings/keyways cast directly against undisturbed, stiff soils in a trench may be designed for passive resistance against lateral translation using an equivalent fluid equal to 300 pounds per cubic foot (pcf). The passive equivalent fluid pressure diagram begins at the top of the footing, however, total lateral resistance should be summed only over the depth of the actual key (truncated triangular diagram). This value applies only to footings/keyways where concrete is placed directly against the trench sidewalls without the use of forms. If footings are placed on grade and then backfilled, the top of the compacted backfill must be horizontal and extend outward from the footing for a minimum lateral distance equal to three times the height of the backfill, before tapering down to grade. The passive resistance value includes a factor of safety equal to 3 in order to reduce the amount of movement necessary to generate passive resistance. The friction coefficient for footings cast directly on undisturbed, stiff . soils may be taken as 0.3. This is an ultimate value and does not include a safety factor. 15.0 DRAINAGE CONSIDERATIONS All perimeter foundation walls and grade beams should be provided with a drain at the grade beam base elevation. Drains should consist of rigid, PVC, perforated pipe backfilled within 1 foot of ground surface with washed drain rock. The size of the drain rock must be greater than the diameter of the pipe perforations. The bottom of the pipe should be set approximately 2 inches below the bottom of the foundation and should be constructed with sufficient gradient to allow gravity discharge away from the homes. Roof and surface runoff should not discharge into the footing drain systeni but should be handled by a separate tightline drain. In planning, exterior grades adjacent to walls should be sloped downward away from the structures to achieve surface drainage. All drains must be either tightlined to a suitable engineered storm water conveyance system or tightlined to the bottom of slopes. If tightlining drains over slopes, the pipe should consist of a minimum 8 inch diameter HDPE pipe. The pipe must be anchored at the top of the slope and should be routed on the surface of the slope. The anchor should consist of the pipe fastened to a concrete catch basin fitted with an overflow grate. Yard/landscape drains should be provided as necessary. 16 I 16.0 PROJECT DESIGN AND CONSTRUCTION MONITORING We are available to provide additional geotechnical consultation as the project design develops and possibly changes from that upon which this report is based. This is especially important since periodic monitoring of the site is planned throughout the winter. In addition, no foundation plans were available for the residence at the time our work was completed. We recommend that AESI perform a geotechnical review of the foundation and site plans prior to final design completion. In this way, our earthwork and foundation recommendations may be properly interpreted and implemented in the design. We are also available to provide geotechnical engineering and monitoring services during construction. The integrity of the foundations depends on proper site preparation and construction procedures. In addition, engineering decisions may have to be made in the field in the event that variations in subsurface conditions become apparent. We have enjoyed working with you on this study and are confident that these recommendations will aid in the successful completion of your project. If you should have any questions, or require further assistance, please do not hesitate to call. Sincerely, ASSOCIATED EARTH SCIENCES, INC. Kirkland, Washington Joseph B. Clare, E.I.T. Staff Geotechnical Engineer Ronald A. Parker, P.G. Principal 1BC/,d G97224A 1 10/1/97 Id - W97 Bruce L. Blyton, P.E. Associate Engineer v/;'s/C17 17 ,, ELEVATION IN FEET LU 0 0 0 r •r- N N r QC a y a Z LU L0 uw 0 n w = Q o 3 T a a W v) 3g A~ 0 Z r- O Na Oa 02 Q e Q W N N ti C7 C ae 73 T � � ca Wcc �, I U Z U 0 F= LOUo-' NQW U o NaU � o o QWN Ch a m m V W of ' o ? M U o Q m U W 2 E' ►UA Ir W LU J wq H � ; y a 0 a� c N 0 T T T 133zi NI NOLMA313 i� !V NORTHEWIV RAILROAD ' - - - - - - - - - - - - - - - - - - - - - - - - - 22 - ----24 - - - - - - - - , =-26 3 2- - — — — — — — — 36-8 -i- .- :'••. i •�:.+.' . - • • :�: , • `ice - - - - - -- - - 4442 48-1 -5250 _56 54 o _60 62 - - - - - - w co - - ---64- - ;:- - - - - 62> - - 66 - - - - -_-'-- - - s - - - -64 �_/��'/� -6pL rn —68 70 - - - ,76 (A-0 Rl X- =78 o r � / co - rnm� p v_ A ti 2 �m —cz m -i rn v / AA A 2 o '9 Z39 ! ♦ —178 go cn -94 —98 102 -��\��\--arm Q -92=� // i--'�104. m� cam` ;�' �// � 0� (a O \'o �106 CO m� y o '10$ m O 91 C "' m 110 ?E-- ^, / 14 116 SQfl- _ _ _ _ _ - _- - �= o dv D 120 _- - S06'39'5," E Z64 -0 -r - -_ _ � _ - - - -L - - - co `. (T \ ASpW -mo �� Nam -cp - c" r OVL....EAU POWER & TELEPHONE a p— O Z_ N ----- o-92 94 02 9 , LO co co ZL OL 99 N Ul 9S OS - - 7 7-7 - t 9 Ot — 82 — — — — — — — — — — — — — Z2 Oi -----.-_-_- - - -gz+ —----9Z 2 U z W Q W u., W L�11jI7�118 °` • U a 13 Z W w O a�v Q W J N M IL to 0 0 x W�ZW NQU M w LI) QWN p OZME oWw.. Q �CmW W a LU CL V/ -a a 0 0 0 0 a a m m O O 0 O 0 0 m z z x x W O O W C J Q Q ® � O W W W W LL = F. Z O 0 O W z Q 1, 0 vi 01 10 I� I' II II I 807 I 'I I I I I �L•. I I .. .SCARP � 98155 A P E 194116.' I I I 1 ( 0 18"MAPLE I 1 1 1 \ J I.I I t i EP.4 18"MAPLL14 I \ / \\ S IEVERGR�® -O RH p POWER _�1%j .I I II llll 1}11 1S\i �(;\ t S1aALDE \ --t- \ 1 PROPOSED 1 =—s HOUSE I i I DILAPIDATED I r 1 ) HOUSE CO 00 L T 1I:II Irdl 11:i1. i j l', - - CQVEED Ir'I. I I I I I J 4 J I, .. I I ' CON ETE I I 'I PATIO 1 ! f % \ �I ll�l I;I.I II,.Ii .nd / � � � c° � CIOI ! i I 1 1 o ! I/ LO V I ! X } If EP-1 l.lt, \ 1 I I I ' 2�40 �; \ \ \ �' \ I I ' EB-3 ° I EB-1t9 IF a DECIDUOUS EP-3 ' r.{ I 1 (:�;•; I I .I t 16.116' h 1f cQ) ! / I 1.1 CIRES I; tI I� III .I IIII ,IIII :I`. 11 1■ I I I ;Ira / I I i i. • NOTE( I I .I ;I / HOC ,WIRE! FENCE I BROKEN FLOWN AND ! (1, / r 96 UNDEFINA LE (r I I I I 1 I 1.-I .I. T{{��ROUGH DENF E I I11 I I i •:. I I I i I: �TENSION I I l (./ PROPOSED X SHED CRACK HOUSE EB-2/1 II II) '1111 .:(Ill :LI I 11 Ir�I.`4i1�. IIII :II I,.� I I �S�I EP2 ao S DILAPIDATED UTILITY 1 III r. r I; CRACK TENSIONI BUILDING I I i ).L I I •1 r I 1 is � \. \ � , h � w\ �, t\\ ":.\ \ j Is \ V. N83'03'43' I I I I I I S S S\ S S I I 1 I I S II I I I I I I S S S IS S S i l V I I I I I I I III I I I I I S S i l l I I I S I I I I I I I I IIII I I T i l l I V I I I I I I I I I I I I I I IIII i 1 I IIL cOaoON4600 Nd cDaoOcv� iDaOOCVd cf>�OCV is 00 600 dCCOrpC tV N r7 r7 r7 r•1 d• -t - un 0 un n to co 0 0 to r r• r, rr r• 00 00' m ' TAMER NORTHWEST, INC. SURVEYORS & PLANNERS SURVEY -TOPOGRAPHIC SURVEY FOR THERESA ALDRIDGE' DATED 9/4/97. LEGEND EP-1 N Approximate location of exploration pit EB-1 0 Approximate location of exploration boring NORTH r FIGURE 1 SITE AND EXPLORATION P ALDRIDGE SHORT PLAT EDMONDS, WASHINGTON PROJECT NO. G97224A SEPTEMBER 1997 3n an QCrintf A qr =w 9EXPLORATICi4 PIT LOG 0 Meimhar FP-1 5 10 15 Kbimhcr FP-2 N 5 10 15 Subsurface conditions depicted represent our observation at the time and location of this exploratory hole, modified by geologic interpretation, engineering analysis, and judgment. They are not necessarily representative of other times and locations. We will not accept responsibility for the use or interpretation by others of information presented on this log. Reviewed By Associated Earth Sciences, Inc. Aldridge Short Plat 911 Fifth Avenue, Suite 100 Edmonds, Washington Kirkland, Washington 98033 Project No. G97224A Phone: . 425-827-7701 September 1997 Fax: 425-827-5424 9EXPLORATICiJ PIT LOG Number EP-3 0 5 10 15 — 0 5 10 15 Loose/soft, moist, dark brown, silty, fine SAND with roots. (Fill) Loose, moist, brown, medium SAND. (Fill) Loose, moist, reddish -brown, medium SAND with occasional gravel. (Fill) Stiff to very stiff, moist, bluish -gray, silty CLAY. (Possession Drift) BOH @ 18' Note: No seepage; caving. Number EP-4 Loose, dry, dark brown, silty, fine SAND with occasional gravel, roots, chunks of asphalt. (Fill) Loose, damp, reddish -brown, medium SAND wtih occasional gravel. (Fill) Stiff to very stiff, moist, bluish -gray, silty CLAY; slickensided surfaces; upper 1' slide debris. (Possession Drift) BOH @ 16' Note: No seepage; caving 0 to 8'. ) Subsurface conditions depicted represent our observation at the time and location of this exploratory hole, modified by geologic interpretation, engineering analysis, and judgment. They are not necessarily representative of other times and locations. We will not accept responsibility for the use or interpretation by others of information presented on this log. Reviewed By Associated Earth Sciences, Inc. 911 Fifth Avenue, Suite 100 Aldridge Short Plat Kirkland, Washington 98033 Edmonds, Washington Phone: 425-827-7701 Project No. G97224A - Fax: 425-827-5424 September 1997 ~` EXPLORATIBORING LOG ` Number EB-1 Page 1 of 2 � STANDARD PENETRATION a. Z W RESISTANCE SEDIMENT DESCRIPTION IL O Q Blows/Foot OQ to 0 10 20 30 40 Damp, light brown, silty, fine SAND with trace roots; 8A bottom of sample damp, light brown with gray SILT I with trace fine sand. 1 Damp, brown, silty, fine SAND with lenses of silt with - 5 4 trace fine sand; tip of sample damp, reddish -brown I A i SAND with some small gravel. Damp, reddish -brown SAND with trace gravel. I 5 I No recovery. (Fill) 10 14 .............................. ..-----..........---7...................... ?------------.....----?............ ' i Moist to wet, light brown, silty, fine SAND; top of sample I 8� black charcoal with fine sandy silt. i 15 6A l ' Moist, brown, silty, fine SAND: tiny roots observed. I Damp to moist, blue, silty CLAY, plastic. I A Moist, blue, silty CLAY, laminated. 20 I I 12 A t Moist, blue,. silty CLAY to clayey SILT. I i� I I t � Moist, blue, silty CLAY to clayey SILT. 25 I I ; i A 22 Moist, blue, silty CLAY to clayey SILT. I 118� I Moist, blue, silty CLAY to clayey SILT with lenses of 30 I (� 22 fine, oxidized sand; slickensided surfaces observed. (Possession Drift) t ........................................................................................................................ Damp to moist, light brown, silty, fine SAND, upper I 70 portion oxidized. (Double Bluff Drift) Subsurface conditions depicted represent our observations at the time and location of this exploratory hole, modified try geologlc Interpretations, engineering analysis, and Judgment. They are not necessarily representative of other times and locations. We will not accept responsibility for the use or Interpretation by others of Information presented on this log. Reviewed By Associated Earth Sciences, Inc. Aldridge Short Plat 911 Fifth Avenue, Suite 100 Edmonds, Washington Kirkland, Washington 98033 Project No. G97224A Phone: 425-827-7701 September 1997 Fax: 425-827-5424 EXPLORATION! BORING LOG Number EB-1 Page 2 of 2 STANDARD PENETRATION Z W RESISTANCE SEDIMENT DESCRIPTION w g 0 Q Blows/Foot 10 20 30 40 48A (Double Bluff Drift) i I BOH @ 36-1/2' I Note: Slope inclinometer installed. 40 I I I 45 I 50 I I i 55 I 60 I i I 65 __. i--..w.....s M.io e�...lnr mry Min_ modified by Geolop1C subsurface conditions depicted represent our ooservauons — — w..a -••- - - -- --- - - - interpretations, engineering anaysis, and Judgment They are not necessarily representative of other times and locations. We Will not accept responsibility for the use or Interpretation by others of information presented on this tog. Reviewed By Associated Earth Sciences, Inc. Aldridge Short Plat 911 Fifth Avenue, Suite 100 Edmonds, Washington Kirkland, Washington 98033 Project No. G97224A Phone: 425-827-7701 September 1997 Fax: 425-827-5424 X r • EXPLORAT106 BORING LOG " Number E13-2 Page 1 of 2 4 STANDARD PENETRATION ' a Z W RESISTANCE SEDIMENT DESCRIPTION o Q 0 R Bit v7 � 10 20 30 40 Damp, brown, fine to coarse SAND with trace fine (Fill) I � -- gravel------------------------------------ ------------------------------------ Damp, light brown SILT in top of sample; damp, light 5 T 7 gray, clayey SILT to silty CLAY in bottom of sample. 1 Damp, gray, silty CLAY. (Slide Debris) I Al2 Damp, gray, silty CLAY. 10 1i 16A Moist, bluish -gray, clayey SILT to silty CLAY. I 64 Moist, light brown, fine SAND in top of sample; moist, 15 T i 10 bluish -gray, silty CLAY in bottom of sample. 1 f Moist, bluish -gray, silty CLAY; wet, medium SAND in I i 30 tip of sample. 1 Moist, bluish -gray, silty CLAY. 20 I 14 i i Moist, bluish -gray, silty CLAY; fine sand tense in middle I I 34 A of sample. � Moist, bluish -gray, silty CLAY; medium sand lense in 25 I � ` ' I 27 middle of sample. (Possession Drift) 1 j A Damp to moist, light brown, fine SAND at top of sample; I , 38 A medium sand lower half of sample. 1 30 I 73 Damp to moist, light brown, fine SAND. Damp to moist, light brown, fine SAND. I I 65 (Double Bluff Drift) Subsurface conditions depicted represent our observations at the time and location of this exploratory hole, modified by geologic Interpretations, engineering analysis, and Judgment. They are not necessarily representative of other times and locations. We wail not accept responsibility for the use or Interpretation by others of Information presented on this log. Reviewed By Associated Earth Sciences, Inc. Aldridge Short Plat 911 Fifth Avenue, Suite 100 Edmonds, Washington Kirkland, Washington 98033 Project No. G97224A. Phone: 425-827-7701 September 1997 Fax: 425-827-5424 ik • EXPLORATION BORING LOG . Number E13-2 Page 2 of 2 SEDIMENT DESCRIPTION F=- Q a Z w Q 0 U STANDARD PENETRATION RESISTANCE Blcws/Foot 10 20 30 40 (Double Bluff Drift) i 62 BOH @ 36-1/2' 40 i I I 45 i 50 I i � f I i I I I 55 I 1 i i i 60 � I I I r 65 j Subsurface conditions depicted represent our observations at the time and location of this exploratory nose, moamea oy geoiogic Interpretations, engineering analysis, and judgment They are not necessarily representative of other times and locations. We will not accept responsibility for the use or Interpretation by others of Information presented on this log. Reviewed By Associated Earth Sciences, Inc. Aldridge Short Plat 911 Fifth Avenue, Suite 100 Edmonds, Washington Kirkland, Washington 98033 Project No. G97224A - Phone: 425-827-7701 September 1997 Fax: 425-827-5424 ' 3 EXPLORATION BORING LOG Number EB-3 Page 1 of 2 = w z W STANDARD PENETRATION I— � Z w RESISTANCE SEDIMENT DESCRIPTION o Q 0 , Bi t CD 0 10 20 30 40 Moist, orangish-brown, silty SAND. (Fill) 1 5 • I Moist, gray, clayey SILT (Slide Debris) 5 7• Moist, gray, silty CLAY to clayey SILT. I 1 •12 I Moist, bluish -gray, silty CLAY with moist, brown, fine in 10 T 1 • 14I j sand lenses 4" thick middle of sample. Ij Moist, bluish -gray, silty CLAY; fine sand lense in T 15• I middle of sample. Moist, bluish -gray CLAY; 6" thick lense of peat with silt; 15 I I � I 28 • slickenside surfaces. (Possession Drift) 1 ............................................................................... Damp, light brown, fine SAND. I ( 34 • Damp, light brown, fine SAND; very fine sand to silt lense 20 T 1 30 in middle of sample. 1 Damp, light brown to gray, fine to medium SAND. T I j 57 Damp, light brown, fine SAND; moist, brown, fine SAND 25 69 in bottom of sample. I Moist, brown, fine SAND. 1 I 81 Moist, brown, fine SAND. 30 f 71 Moist, brown, fine SAND. I 82 Subsurface conditions depleted represent our observations at the time and location of this exploratory hole, modified by geologic Interpretations, engineering analysis, and judgment. They are not necessarily representative of other times and locations. We will not � accept responsibility for the use or Interpretation by others of information presented on this log. Reviewed By aEl Associated Earth Sciences, Inc. 911 Fifth Avenue, Suite 100 Kirkland, Washington 98033 Phone: 425-827-7701 Fax: 425-827-5424 Aldridge Short Plat Edmonds, Washington Project No. G97224A September 1997 :i. Number EB-3 0 Page 2 of 2 EXPLORATION BORING LOG SEDIMENT DESCRIPTION 1-- o J Z W Q 0 R � STANDARD PENETRATION RESISTANCE Blows/Foot _. 10 20 30 40 i 64 (Double Bluff Drift) I BOH @ 36-1/2' Note: Slope inclinometer installed. 40 i i 45 I i I � ` 50 1 I 55 j i 60 � 1 —65 I 1 Subsurface conditions depicted represent our observations at the time and location or tnrs expioratory nove, moomeo oy geotogic Interpretations, engineering analysis, and judgment. They are not necessarily representative of other times and locations. We will not accept responsibility for the use or Interpretation by others of information presented on this log. Reviewed By Associated Earth Sciences, Inc. 911 Fifth Avenue, Suite 100 Kirkland, Washington 98033 r Phone: 425-827-7701 Fax: 425-827-5424 Aldridge Short Plat Edmonds, Washington Project No. G97224A September 1997 J7 �0�XA+--1�J VW1 4 ZS' LANDAU ASSOCIATES, INC. Environmental and Geotechnical Services Ms. Lara Knaak City of Edmonds 250 5th Avenue North RECEIVED APR 2 01999 DEVELOPMENT SERVICES CTR. CITY OF EDMONDS Edmonds, WA 98020 - - --- — RE: PRELIMINARY GEOTECHNICAL REVIEW PROPOSED ALDRIDGE SFR 15604 - 75TH PLACE WEST EDMONDS, WASHINGTON Dear Ms. Knaak: April 19, 1999 In accordance with your request, Landau Associates has completed a preliminary geotechnical review of construction plans and other submitted documents concerning the proposed Aldridge residence, to be located at 15604 75`s Place West in Edmonds, Washington. Our review follows requirements outlined within City of Edmonds (City) Ordinance No. 2661. A list of the documents that were provided to us for review are referenced in Attachment 1. The site is located within the Meadowdale landslide area, at the north terminus of 75th Place West, between 75th Place West and the Burlington Northern Santa Fe Railroad (BNSF) right-of-way. This property is reported to have been involved in landslide movement in 1955-1956, and is also reported to have experienced localized slope instability in 1997. Information from the 1968 Dames and Moore and 1979 Roger Lowe Associates reports regarding the subject site, along with discussions with Ms. Jeannine Graf of the City of Edmonds, provide a historical perspective on this reported slope movement. The following summarize our comments on the submitted documents. GENERAL Several items were not included in the submittal package we received that are required by City Ordinance No. 2661. The following items were not included in the submittal: 0 Environmental Checklist 0 Structural Design Calculations • Affidavit of "Notice of Application Posted at Site" • Lead Design Professional statement on drawings' • Architect and Structural Engineer Declarations • Covenant to Notify / Hold Harmless. Agreement WAPATO CREEK PLACE - 4210 - 20TH STREET E. • SUITE F TACOMA, WA 98424-1823 (253) 926.2493 Fax: (253) 926-2531 E-Mail: info@Landauinc.com Edmonds Spokane Tacoma Though the above documents are not required to complete our review of the geotechnical aspects of the project, the. City should require submittal of these documents prior to issuing. a building permit. In addition, City Ordinance No. 2661 requires that a lead design professional be identified for each project. The applicant will need to identify this lead design professional, unless the City waives this provision. GEOTECHNICAL REPORT The October 1997 geotechnical report, prepared by Associated Earth Sciences, Inc. (AESI) and submitted by the applicant, discusses geologic hazards and provides preliminary geotechnical engineering recommendations for .site development. The report does not specifically address the proposed site development. Based on our review of the submittal documents, several items still need to be addressed by the geotechnical engineer, including: • An evaluation of possible impacts to site stability due to groundwater • Further analyses/discussion regarding deep seated landslide potential • Recommendations for temporary excavation slopes/shoring requirements • Recommendations for rockeries/retaining walls along the driveway The above items, along with additional comments on the October 1997 geotechnical report, are discussed in greater detail below. The stratigraphy, as interpreted by AESI in the geotechnical report, consists of a sequence of fill, Possession Drift and Double Bluff Drift.. Review of boring logs in the 1979 Roger Lowe report indicates that the undisturbed Possession Drift (referred to as the Whidbey Formation) typically has SPT blow counts in excess of. 50, while the borings completed by AESI (EB-1 through EB-3) show SPT blow counts in the range of 10 to 30 for the unit interpreted as Possession Drift. These blow counts are similar to those for soil identified in the 1979 Roger Lowe report as "landslide material". Also, boring EB-1 encountered clay with slickensides and oxidized sand layers at a depth of about 30 ft, just above the .. contact with the Double Bluff Drift. Based on the lower SPT blow counts recorded in the AESI borings, and the presence of slickensides, it is our opinion that the soil identified as Possession Drift in the summary boring logs has been disturbed by past slope movements. Landslide Hazard Based on our review of AESI's October 1997 report, and our discussions with Ms. Jeannine Graf of the City of Edmonds, it is our opinion that the landslide hazard at the site has not been fully evaluated. According to a 1968 Dames and Moore report, the 1979 Roger Lowe report, and the 1997 AESI report, the site was subjected to slope movements during the winter of 1955-1956. 04/19/99 I:\PROJECT\074W83\iWdgeSFR_Rr.doc. LANDAU ASSOCIATES. 2 0 Even though drainage improvements related to stabilization of the Meadowdale landslide were implemented in the 1980s, the site has continued to show indications of soil movement. In the October 1997 AESI report, tension cracks were identified at the site and were inferred to be related to a shallow slide plane possibly located near the contact of the fill and upper part of the Possession Drift unit. AESI recommended in the report that the site be monitored for continued soil movement, but it is unknown if this monitoring was ever completed. From our discussions with Ms. Jeannine Graf of the City of Edmonds, we understand that the tenants who had lived at the site moved out in the winter of 1997 because of concerns of ongoing slope movement and formation of tension cracks at the site. Based on this history, it appears that the site has not benefited substantially from the City's drainage improvements. In Section 6.0 of the 1997 AESI report, they discuss the potential of a deep-seated landslide and recommend monitoring of two slope inclinometers installed at the site to assist in the evaluation of whether the potential deep-seated slide plane is active or not. In addition, since AESI's explorations were completed during the dry summer months, the report states that an accurate assessment of potential groundwater conditions was- not possible, and recommends that the site be monitored for possible slope movement, seepage/spring activity, or other drainage concerns in order to evaluate potential impacts to slope stability. No documents and/or discussions of the recommended monitoring (inclinometers, groundwater, and slope movement) were included in the documents submitted. In Section 5.2 of the AESI report, they conclude that the risk of seismically induced landsliding of the slope to the east (along the west side of 75`s Place West) and to the west (along the BNSF right-of- way) is low. We concur with AESI's opinion regarding the west slope along the BNSF right-of-way, but question their conclusion regarding the slope along the west side of 75 h Place West. AESI's conclusions about the slope along the west side of 75`h Place West is based partially on the lack of the presence of adverse groundwater conditions and, (based on shallow probing), that the hillside core is composed of consolidated, (native) sediments. Since AESI's explorations were completed during early September when groundwater levels are generally at their lowest levels, it is not known how they could conclude that there are no adverse groundwater.conditions present at the site. Probing of the surficial soil on the slope along the west side of 75's Place West reportedly indicated stiff (native) sediment is present below a depth of a few feet. However, based on the topography shown on the Site Topography Drawing, and our understanding of the area from previous reviews, the portion of 75°i Place West adjacent to the site may be underlain by a significant amount of road fill that may have been placed with little or no engineering controls. Deeper borings would be needed to allow proper characterization of the soil composing the slope along the west side of 75`s Place West and the landslide hazard, under both static and dynamic conditions. 04/19/99 I:%PROJECT\074VQ83\aldridgeSFR_Itr.doc LANDAU AssociATEs 3 • The entire site is contained within a mapped landslide block, which reportedly experienced movement during the winter of 1955-1956 (Dames and Moore 1968). The mapped landslide block extends from the railroad right-of-way to near the base of the hillside east of 75's Place West, and from about the north property line to about 200 ft south of the south property. No discussion is provided in the report regarding the potential of reactivation of the 1955-1956 landslide block during.a seismic event. AESI indicates that. the site will likely be subjected to a magnitude 5.5 to 6.0 earthquake within the next 8 to 12 years. Therefore, the effect of.this earthquake on site stability should be evaluated. We recommend that AESI reevaluate the landslide hazard at the site. The analyses should include the inclinometer data and groundwater monitoring data per their recommendations. If the data is not currently. available, then additional monitoring of the inclinometers and groundwater levels appears warranted. Temporary and Permanent Excavations Sheet C1.1 of the Civil Drawings shows a 4 to 5 ft high rockery along the east side of the drive at the toe of the slope supporting 75`s Place West. Cutting into the toe of this slope for a rockery could destabilize the slope. In addition, a rockery may not be an appropriate retaining structure for such an embankment. No discussion/recommendations for rockeries or retaining structures for the slope are provided in AESI's October 1997 report. We recommend that AESI address this concern. In addition, if the City has a slope easement along the west side of 75's Place West, their permission would be required to construct the rockery, or any other retaining system. Review of Sheets.7, 8, and 9 of the construction drawings indicate that temporary cuts of up to 16 ft could be required to construct the foundation of.the lower floor. No recommendations or discussions regarding temporary excavation slopes at the site are provided in either the October 190 AESI report or their February 23, 1999 letter.of review of the construction drawings. Because. of the potential for instability of temporary cut slopes, AESI must provide recommendations for appropriate temporary . excavations and/or temporary shoring. Wall Backfill Though AESI's October 1997 report provides general recommendations for placement and compaction of site fill, .no specific recommendations are provided regarding backfilling behind below= grade walls of the proposed structure. Since the fill will underlie portions of.the upper floors (which we understand are structural slabs), it is important that the fill be properly placed and compacted to prevent future settlement which could affect underslab utilities. We recommend that,AESI review and comment on this issue. 04/19/99 I:IPROJ ECT\074\083\aldridgeSFR_ftr.doc LANDAU ASSOCIATES 4 Lateral Pile Capacity Though the October 17, 1997 report provides recommended lateral capacities for auger -cast pile foundations, no guidance is provided on the use of the recommended lateral pile capacity for resisting wind and/or seismic loading, soil movement, etc. In addition, if the deep seated landslide were to reactivate, the piles would offer little, if any resistance .to soil movement. We recommend that AESI review and comment on this issue. Passive Earth Pressure The October 1997 report recommends using a passive soil resistance of 300 pcf (including a factor of safety of 3 to reduce the amount of movement necessary to generate passive resistance) to resist lateral translations. In our opinion, a value of 300 pcf would be appropriate for a dense to, very dense or hard glacially consolidated soil, which extends laterally in the direction of loading a distance equal to or greater than twice the embedded depth. The fill and disturbed Possession Drift soil at the site is of poor quality and, in our opinion, probably could not develop the recommended passive resistance and maintain a factor of safety of 3.0. We recommend AESI review and comment on this issue. DRAINAGE CALCULATIONS The drainage calculations prepared by CG Engineering reference the wrong site address (16504 75'h Place West). To avoid future confusion, we recommend that the correct address be shown on the document. GEOTECHNICAL PLAN REVIEW The only item that appears to have not been corrected, as recommend by AESI in their February. 23, 1999 review of the project plans, is the addition of clean outs on the perforated dispersal pipe (Sheet . C2.2, Detail 4). We recommend that this recommendation be followed. In summary, it is our opinion -that the landslide hazard at the site has not been adequately characterized. In addition, several issues need to be addressed by the. geotechnical engineer- as noted above. We recommend that the documents be returned to the applicant for further action, and a lead design professional should be -designated. The lead design professional should review the plans and other documents and make whatever appropriate changes are necessary in order to be consistent with the requirements of Ordinance 2661. In addition, the design professionals (Geotechnical Engineer, Structural Engineer, and Civil Engineer responsible for site stormwater drainage design) should evaluate and comment on specific issues raised herein-. 04/19/99 I:\PROJECT\074X083\aldridgeSFR_Kr.doc LANDAU ASSOCIATES 5 Please call if you have questions concerning this review, or require the services of Landau Associates for subsequent review services. EJHIWDE/jas 04/19/99 I:\PROJECT074\0831aldridgeSF R_ttr.doc LANDAU ASSOCIATES, INC. By: Edward J. Hea ey, P.E. Senior Engineer and William D. Evans, CPG Associate LANDAu AssoaAns 2 ATTACHMENT 1 • Subsurface Exploration, Geologic Hazards and Preliminary Geotechnical Engineering Report, Aldridge Short Plat,Edmonds, Washington, prepared for Ms. Theresa Aldridge by Associated Earth Sciences, Inc. Project No. G97224A, October 1997. • Geotechnical Plan Review, Aldridge Residence, 15604 75`h Place West, Edmonds, Washington, prepared for Ms. Theresa Aldridge by Associated Earth Sciences, Inc. Project No. KE97224A, February 23, 1999. • Drainage Calculations for: Aldridge Residence 16504 75 h Place West, Edmonds; Washington, prepared by CG Engineering, Project No. 98092.21, December 31, 1998. Construction Drawings, New Residence for Theresa Aldridge, Sheets 1 through 19, prepared by Terence C. Watson, dated February 4, 1999. • Topography Survey prepared by Cramer Northwest, Inc., dated November 1998. • Civil Drawings, Sheets CIA, C2.1, and C2.2, prepared by CG Engineering, Project No. 98092.21, February 23, 1999. • Owners Liability Statement, dated February 25, 1999 by Theresa Aldridge. 04/19/99 I:XPROJECT O74\083\aldridgeSF R_hr.doc LANDAU ASSOCIATES 7 RECEIVED CORPORATE OFFICE ASSOCIATEO 911 Fifth Avenue, 5uiie 100 EARTH JAN 1 8 2000 Kirkland, Washington 90033 (425) 827-7701 SCIENCES, INC FAX (425) 827.5424 BAINDMOE ISLAND OFFICE 179 Madrone Lune North Bainbridge Idond, WA 98110 January 18, 2000 (206) 780.9370 Project No. KE97224A FAX (206) 780.9456 Reed and Associates 8311 -- 212" Street SW Edmonds, Washington 98026 t� Attention: Robert Hughes Subject: Cylinder Pile Retaining Wall Aldridge Single-Fanuly Residence 15604 -- 75"' Place West Edmonds, Washington Reference: City of Edmonds Response Letter by Jeamvne L. Graf, October 27, 1999 Tear Mr. 1-lughes: Associated Earth ,Sciences, Inc. (AESI) has completed additional geotechnical study with regards to the design and installation of a cylinder pile wall for the Aldridge property. Our scope of work included evaluating ground water conditions on the property, computer slope stability modeling, and developing geotech.nical. design . parameters and installation recommendations for the retaining structure. BACKGROUND In reference to the above; City of Edmonds letter dated October 27, 1999, to satisfy the: requirements set forth by the City, the owner has chosen to proceed with the design and installation of a retaining structure. This structure is intended to mitigate against landslide hazard for both proposed north and south lots of the Aldridge short plat. SITE CONDITIONS Since, AESI's initial geotechnical report dated October 1997, additional geoteclulical field study has included the monitoring of slope inclinometers, the installation of two shallow ground water monitoring standpipes, and surface reeon.naMance. 'Additional geotecluiical analyses performed included computer stability modeling of the existing and proposed post -construction conditions of the property, Based on the installation of two ground water standpipes, ground water has been observed at shallow depths ranging between 2 and 3 feet below ground surface. The two standpipes were hand installed and located within the western end of the northern half of the property (near the top of the western slope). Ground water observations were made on December 14, 1999 at a tinic of extended wet weather. Due to the fractured and non -homogenous soil texture, the presence of ground water is expected to vary with location. The impacts of a. high ground water, table have been considered in the design of the wall and in home construction. Proposed deep excavation for the basement of the home and the installation of foundation wall drainage will intercept a portion of the shallow ground water observed on -site. No deep ground water was observed within our initial geoteeluucal exploration borings and the shallow ground water on -site has been interpreted as seasonal perched ground water. The movement of the water through the silt and clay will be through fractures and sand lenses in contrast to movement throughout the soil ut-k Additional field recotuiaissance has not shown an appreciable change in the surface topography of the site since AESI's original study in late 1997. However, slight soil movement has been measured in the two slope inclinometers as reported in AESI's ruly 22, 1999 letter. RETAINING WALL As currently proposed, the retaining structure consists of a cylinder pile wall. This wall consists of closely spaced, reinforced concrete soldier piles. Since timber lagging is not used between the piles, the edge -to -edge pile spacing is designed to utilize soil arching for lateral restraint of the retained soil. The soldier piles will be completed below grade and located near the top of the western slope. The wall will extend from the northern property line to within about 50 feet of the southern property line. Piles will consist of 24-inch-diameter augered holes filled with concrete. Per the structural engineer's design, W 16 x 89 steel beams will extend the full depth of the augered holes and spaced on 6-foot centers (4 feet edge to edge), The piles will be embedded a minimuin of 20 feet into bearing soils (Double Bluff Drift) with about 1.3 feet of retained soil. Final pile locations may be field adjusted to minimize impacts to - the slope. The recommended � lateral earth pressure for the upper 13 feet of retained soil (slide dcbris/Possession Drift) is 117 pounds per cubic foot (pcf) equivalent fluid, acting over the 6- foot pile spacing. This value includes saturated soil forces with sloping topography behind the wall. An equivalent fluid of 67 pcf acting over one pile diameter (2 feet) should be used within the bearing soils below 13 feet depth (Double Bluff Drift). A passive resistance of 400 pcf equivalent fluid should be used for the lower 20 feet (Double Bluff Drift) of the downslope end of the pile. The passive resistance acts over two pile diameters (4 feet). Computer modeling of slope stability demonstrates an increase in the factor of safety following construction of the soldier pile wall.. The computer model was developed such that the existing slope and geologic conditions provided a factor of safety equal to 1. The impact of a high 2 H ground water table was included in the model. Following construction of the wall, the factor of safety increases, to 1.15 under static (non -seismic) conditions and assuming no decrease in the ground .water level on the property. Under seismic conditions, a factor of safety of < 1 was modeled, indicating that a large earthquake (greater than TO magnitude, 0.2g Horizontal acceleration) would likely result in wall damage. Additional reinforcement of the slope will be realized following excavation and installation of home foundation piles, but this benefit was not relied upon in the computer model. During the design life of the wall, downslope soil movement may occur on the west side of die wall (downslope). If erosion between the individual piles occurs, tunber or concrete lagging can be installed to shore the upslope soils. INSTALLATION RECOMA ENDATIONS AEST should be on -site during pile installation. to verify that construction is in accordance to the :approved plans and specifications. The AESI field representative will document individual pile depths, embedment, and verify that subsurface conditions are consistent with the design. CONCLUSIONS In our opinion, the construction of the soldier pile wall is a suitable mitigation for the potential of shallow earth movement on the property. The impacts of a high ground water table have been considered in the design of the wall and in home construction. Should you have any questions, or require further assistance, please do not Hesitate to call. Sincerely, ASSOCIATED EARTH SCTENCES, INC.' Kirkland, Washington os7 p B. Clare, E.I.T. Senior Staff Geotechn.ical Engineer cc: Theresa Aldridge 18330 Olympic View Drive Edmonds, Washington 98020 ills 110 • KL•97224A7 - LD-D:\I01.00 • W2K $ O r! 290� �L EXPIPES Bruce L. Blyton, P.E. 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Q' CQ U'N Ot0 9204160927 a "Co*i...�°.. ;01(SU OS280£8)OV . .10((iROA010moa • 1 X= O;T00£60£8)18- Y C,(69Z0£Z90£9)5V ',V Associated -Earth, Sciences, Inc. May 7, 200 G Project No. KE03034A All - 7 ?044 Vivian Bennett and Tommy Fong c/o Thienes/Williams Architects, PLLC 3201 First Avenue South, Suite 209 Seattle, Washington 98134 Attention: Mr. Paul Thienes, _ Subject: Bennett/Fong Property Demolition of Derelict Structures 15604 750 Place West Edmonds, Washington Edmonds Permit Nos. 2003-0647 and 2003-0468- . Dear Mr. Thienes: Associated Earth Sciences, Inc (AESI) has prepared this letter to summarize the work that has been completed' at the subject site. The demolition of the derelict structures has been completed in .accordance with the recommendations -of AESI and the permit fP quirements established by the City of Edmonds. Work on the 'site began on February 17, - 2004 with the required pre -construction meeting. Erosion control measures. including the silt fence along the west side of the property, the. quarry spall construction entrance, and the gravel roads, , were completed by the contractor under par -time observation by AESI. AESI com^leted a site visit on May 5, 2004 and observed that the derelict structures had been removed to the concrete foundations. All voids and depressions had been backfilled with "hog fuel". The erosion control measures noted above remain in place and are performing adequately. 911 Fifth Avenue, Suite 100 • Kirkland, WA 98033 • Phone 425 827-7701 • Fax 425 827-5424 • If you have any questions concerning this.. letter, or wish to schedule a pre -construction meeting, please contact me. Sincerely, ASSOCIATED EARTH SCIENCES, INC. Kirkland, Washington Wks Bruce L. Blyton, P.E.- Principal Engineer BLBMa . KE03034A6 Projocts\2003034\K E\W P-W2K — 2 Associated Earth Sciences, Inc. January 22, 2004 Project No. KE03034A Vivian Bennett and Tommy Fong c/o Thienes/Williams Architects, PLLC 3201 First Avenue South, _Suite 209 Seattle, Washington 98134 Attention: Mr. Paul Thienes Subject: Bennett/Fong Property Demolition of Derelict Structures 1-5604 75Place West Edmonds, Washington -Edmonds Permit Nos. 2003-0647 and 2003=0468 Dear Mr. Thienes: As requested, we have reviewed the permit documents sent to our office on January 16, 2004. Based on the information contained in this packet, and our knowledge of site conditions, it is our opinion that. the permitted demolition work may -proceed at any time, provided that the following conditions are met. 1. Prior, to commencing work, a pre=construction meeting should be held with Associated Earth Sciences, Inc. (AESI) to review the approved plan and permit requirements, and coordinate inspection demolition activities. J 2. Access and site preparation, site demolition, and restoration work should be completed during . periods of no rainfall. If significant precipitation occurs on a given workday, . work. should be suspended., the site stabilized, and work should not resume until precipitation has stopped. 3. All work must be executed in accordance with the approved permit documents. 4. AESI will provide daily construction monitoring on a part-time basis, as the work progresses. Daily field reports will be provided to Thienes/Williams Architects, PLLC with copies to the City of Edmonds. 911 Fifth Avenue, Suite 100 • Kirkland, WA 98033 • Phone 425 827-7701 • Fax 42S 827-5424. With the. above conditions, it is AESI's opinion that the demolition work may be completed during periods of dry weather this winter, without increasing the risk of earth movement on the property or on adjacent properties. If you have any questions concerning ..this letter, or wish to schedule of pre=constructiofi meeting; please contact me. , Sincerely, ASSOCIATED EARTH SCIENCES, INC. Kirkland, Washington �� c a,►s,y, 0� , 7- vL( „L Bruce L. Blyton, P.E. Principal Engineer BLB/W KE03034A3 Projcus12003034\KE1WP • W2K. 2 CITY OF EDMONDS 121 5TH AVENUE NORTH • EDMONDS. WA 98020 • (425) 771-0220 • FAX (425) 771-0221 Website: www dedmonds.wa.us DEVELOPMENT SERVICES DEPARTMENT In e 1 gol0 Planning • Building • Engineering November 25, 2003 Mr. Paul Thienes Thienes/Williams Architects, PLLC 3201 First Avenue South, Suite 209 Seattle, Washington 98134 RE: 15604 751h Place West Dear Mr. Thienes: GARY HAAKENSON MAYOR This letter is written to you as representative of Cheung Calvin Trustee and the subject property. As a follow-up to your telephone message to me yesterday, the purpose of this letter is to confirm the Fong's decision to demolish all three buildings/out-structures on the subject property by the City's established deadline of February 22, 2004. As you are aware, there are currently two demolition permits associated with this property: ♦ Permit #2003-0647 for the house and carport and, ♦ Permit #2003-0648 for the shed and utility building; the work on both permits must be completed by February 22, 2004. However, due to the property being located in the designated Meadowdale Landslide Hazard Area, if the Fong's geotechnical engineer of record prohibits work to be completed from now until spring of 2004 (due to wet weather conditions) a letter must be submitted to the City stating this determination. If such a letter is provided prior to February 22, 2004, the City shall extend the life of the existing demolition permits to June 1, 2004. Note, this date is not arbitrary as the dryer season for Meadowdale has been established by City Ordinance to be from May lst to September 301h which gives the Fong's 31 days to complete the demolition work (i.e., May 1st to June 1", 2004). If you or the owner have any questions regarding these date requirements and actions contact me at 425-771-0220 extension 1226. If you wish to meet in person please call in advance for an appointment as I am not always immediately available. Sincerely, Jeannine L. Graf Building Official • Incorporated August 11, 1890 • Sister City - Hekinan, Japan Inc.189v CITY OF EDMONDS 121 5TH AVENUE NORTH • EDMONDS, WA98020 • (425) 771-0220 • FAX (425) 771-0221 Website: www.ci.edmonds.wa.us DEVELOPMENT SERVICES DEPARTMENT Planning • Building • Engineering November 13, 2003. Mr. Paul Thienes Thienes/Williams Architects, PLLC 3201 First Avenue South, Suite 209 Seattle, Washington 98134 . RE: 15604 75th Place West Dear Mr. Thienes: GARY HAAKENSON MAYOR This letter is written to you as representative of Cheung Calvin Trustee and the subject property. In response to your request for an official determination on the three vacant buildings at the subject property, the City Building Inspector met the property caretaker and performed an inspection from the exterior of the building, .to determine if any of the buildings or appurtenances were considered to be dangerous as described in Chapter 3 of the 1997 edition of the Abatement of Dangerous Building Code (ADBC). Based on this inspection the following is my determination: ♦ Regarding the building on the southwest portion of the property; the building may remain provided it is secured (doors and windows boarded) from unwanted entry by children, vagrants or animals. If the owner chooses to board the building the work must be done by December 19, 2003. Failure to meet this deadline shall result in a determination of dangerous building. pursuant to ADBC Section items, 9,12, and 17 (copy of code enclosed) and appropriate action shall be taken by this department. ♦ Regarding the building on the southwest portion of the property; the building may remain provided it is secured (doors and windows boarded) with the exception of the porch --which is determined to be dangerous according to ADBC Section 302, items 1, 2, 3, 5, 6, 8, and 9, (copy of code enclosed) and must be removed. If the owner chooses to remove the porch and board the building, the work must be done by December 19, 2003. Failure to meet this deadline shall result in a determination of dangerous building pursuant to ADBC Section items; 9, 12, and 17 and appropriate action shall be taken by this department. ♦ Regarding the building on the northwest portion of the property; this building is in a partial state of demolition. The majority of the roof structure is removed exposing the interior of the building to weather and animals. This building is determined to be dangerous according to ADBC Section 302 items 3, 5, 6, 7, 8, 9, 11, 12, 15, 17, and 18 and shall be abated by complete demolition by first obtaining a demolition permit from the City. The owner is required to obtain a demolition permit by December 1, 2003 and have the work complete within 180 days of permit issuance. If the geotechnical engineer of record prohibits work to be completed until spring (due to the site location in the Meadowdale Landslide Hazard area complex) a letter must be submitted stating this determination. -Incorporated August 11, 1890 • Cict— 1-iFn - ".1fi .1-- Mr. Thienes November 13, 2003 Page Two If you or the owner have any questions regarding these determinations contact me immediately. In my discussions with you on this matter you have concurred that the one building needs to be demolished, however, if the owner chooses to appeal this decision a formal written appeal must be submitted within 10 working days date of this letter with a complete appeal submittal and filing fee (handout enclosed). If any of the established time frames cannot be met the City requires that a letter be provided with an alternate submittal date.. If you or the Fong's have any questions regarding this letter please feel free to contact me at 425-771-0220 extension 1226. If you wish to meet in person please call in advance for an appointment. It is not the City's intent to cause undue hardship to the property owners, rather to protect the health, safety and welfare of all citizens. Sincerely, Jeannine L. Graf Building Official Friday, November 07, 2003 Re: BE-03-202 Cheung 15604 751h Place West I visited site on 11/6/03, to verify if any dangerous buildings existed at 15604 75" Place West. I was met onsite by the caretaker, Milt. The first building that was looked at was located on the Southeast portion of the property. The building appeared to be structurally sound, except for the porch and porch cover on the South side of the building. They both appeared to be hanging away from the main building. I also noticed a small portion of the roof, located on the West side of the building, which appeared to be hanging down. Most of the windows had been broken out. The second building was located on the Southwest portion of the property, and appeared structurally sound. The door was open and it appeared that most of the windows had been broken out. The third building was located on the Northwest side of the property, and appeared to have been partially taken down. Most of the roof was gone, and there were several stacks of lumber that appeared to have been salvaged from the building. . It appears tome that only the northwest building could be considered a dangerous building, due to the fact that a portion of the .building had been previously taken down. Mike Snook Combination Building Inspector City of Edmonds CITY OF E D M O N D S GARY HAAKEM oR 121 5TH AVENUE NORTH • EDMONDS, WA 98020 • (425) 771-0220 • FAX (425) 771-0221 f Website: www d.edmonds.wa.us DEVELOPMENT SERVICES DEPARTMENT Inc. 189p Planning • Building • Engineering Mr. Paul Thienes October 23, 2003 Thienes/Williams Architects, PLLC 3201 First Avenue South, Suite 209 Seattle, Washington 98134 RE: 15604 75th Place West Dear Mr. Thienes: In response to your letter dated March 26, 2003 received by the City on October 16, 2003 I have the following response: Regarding non -disclosure of information on the property sale, the Fong's may want to contact their real estate agent who presided over the transaction. 2. The City has adopted the 1907 edition of the Abatement of Dangerous Building Code under City Ordinance #3215 (a copy of the ordinance is available from the City Clerk for a fee). This code allows the Building Official to determine that a building is dangerous, declare a public nuisance and require it to be abated by repair, rehabilitation, demolition or removal. The Fong's obtained a permit to demolish, if they have changed their mind and now desire to repair or rehabilitate the structures, a building permit is required prior to the start of work. 3. A design professional is not required in order to file a demolition permit application. However, the City will grant an extension for filing the demolition application to. November 14, 2003 including all applicable permit fees. If the Fong's decide to repair or rehabilitate the existing structures, I shall require that a letter be submitted by November 14, 2003 describing the scope of work for the project and schedule of work (start and completion dates). The repair building permit application, including full plans and fees, shall then be submitted by December 15, 2003. 4. ECDC 19.00.010F1, establishes the time frame of demolition permits at 180 days (copy of code section enclosed). If any of the established time frames cannot be met the City requires that a letter be provided with an alternate submittal date. If you or the Fong's have any questions regarding this letter please feel free to contact me at 425-771-0220 extension 1226. If you wish to meet in person please call in advance for an appointment. Sincerely, Jeammne L. Graf Building Official • Incorporated August 11, 1890 • ii-ter C'itu - Hokinan .ianan nc�.18913 CITY OF EDMONDS 121 5TH AVENUE NORTH - EDMONDS, WA 98020 - (425) 771-0220 - FAX (425) 771-=I Website: www d.edmonds.wa.us DEVELOPMENT SERVICES DEPARTMENT Planning - Building - Engineering GARY HAAKENSON MAYOR Calvin Cheung Trustee October 8, 2003 725 North 185th Street Shoreline, Washington 98133 RE: Tax Account Parcel No. 005131-000-024-09/10, 15604 75' Place West, Edmonds Demolition Permits #2003-0647 & #2003-0648 To Whom It May Concern: The purpose of this letter is to inform the property owner of the subject parcel, that the subject demolition permits expired on September 30, 2003 without project approval. For background information on April 27, 1998 a Stop Work order was issued on this property for demolition work commencing without the required demolition permit (see enclosed copy of stop work order and City letter dated 4/28/98). In response to this Stop Work order, demolition permits were issued to Calvin Cheung Trustee, unfortunately since the demolition permits have now expired, and the work is not complete, the property is again in violation of the code. Pursuant to my authority under Edmonds Community Development Code Chapter 19.05 which regulates property located in the Meadowdale Landslide Hazard Area, I shall require that the current property owner obtain new demolition permit(s) and complete the work subject to geotechnical approval. The demolition permits shall be conditioned to include the following required of a geotechnical engineer: 1) the geotechnical engineer shall determine start of work, 2) required temporary erosion control, 3) protection of exposed soils and hydro seeding, and 4) site winterization requirements after work is complete. For convenience I have enclosed two permit application forms and indicated the areas that need to be completed and the required permit fees. Please complete the forms and return to the City Building Department with full payment by October 22, 2003. Be advised, the demolition bonds associated with the subject permits shall not be released until the work is complete to the satisfaction of the City. If you have any questions regarding this directive please immediately contact me at 425-771- 0220 extension 1226. Sincerely, Jeannine L. ra Building Official Incorporated August 11, 1890 rt - - -- 'r,[-- 11-1-]--- 1---- THIENES/WILLI,WS ARCHITECTS PLLf 3201 First Avenue South #209 Seattle, WA 98134 (206) 623-8733 Fax:(206)6 60 BennettTong Property Demolition of Derelict Structures Questions concerning requirements of Original permit Silt Fence — Discussed the requirement for the entire property to have a silt fence: A. Geotech suggests fence at each structure rather than the entire property length. B. The silt fence ditch digging can cause it own silt problem so one only in the affected areas would reduce the potential for silt. C. The road covering is screened thus eliminating the silt from that process. 2. Road covering — There is a conflict between H2 of "Methodology & Sequence" that calls for 4' to 8" screened recycled concrete and the correction on the drawing concerning this issue where quarry spalls 4" or larger. 3.. Abatement Letter, 13 Nov '03, third paragraph of determination, last sentence — With Edmonds' statement that the work can be done during the rainy season, is this present permit's expiration date incorrect? A. The permit was incorrectly set to expire 9/30/03. B. The permit was issued 8/22/03 and necessarily had to expire 9/25/03 when the termination letter was issued because there was not time to do the work prior to Edmonds expiration date. C. I suggest there may be 146 days left on the permit. D. The permit could resume as soon as the questions I & 2 are resolved. It must be noted that the work may have to be interrupted by weather assuming work can be done in the rainy period. A conversation with the Geotechnical Engineer has revealed the possibility of working during this time. Maybe it could resume when the Geotech certifies work can commence. *, r,Ic.189v CITY OF EDMONDS 121 5TH AVENUE NORTH • EDMONDS, WA 98020 • (425) 771-OM • FAX (425) 771-=I Website: www.ci.edmonds.wa.us DEVELOPMENT SERVICES DEPARTMENT Planning • Building • Engineering April 15, 2003 Paul Thienes 3201 1st Avenue S Suite 209 Seattle, WA 98134 Re: Fong/Cheung Calvin Trustee Demo Application Plan Check # 03-055 Mr. Thienes: GARY HAAKENSON MAYOR The engineering department has determined a $10,000.00 bond will be required for the long term erosion and control measures. The building department has determined a $2,000.00 bond will be required for the demolition permit. We will need two separate bonds since the erosion and control bond will be long term. I have enclosed two types of bond forms for your convenience. One is through a bonding company and the other is for a frozen fund through a financial institution. The type of bond is up to the owner. Please return the completed bonds to Marie Harrison. Thank you. Sincerely, tae Harrison Permit Coordinato Cc: File • Incorporated August 11, 1890 • Sister City - Hekinan..iannn • • RESIDENTIAL DEMOLITION SHORELINE SUBSTANTIAL DEVELOPMENT PERMIT EXEMPTION STREET FILE Project Location: 15604 — 75 h Place W., Edmonds Applicant: Tommy Fong Project Description: Demolish an existing house (900 square feet), carport (418 square feet), shed (180 square feet), and utility building (912 square feet) down to the foundations and slabs. See Attached: 0 Site Plan Plan Check Number: PC-03-53 Date Issued: April 14, 2003 SEPA Determination: Determination of Nonsignificance, appeal period expired June 28, 1999 (demolition of house and structures were considered with an earlier house construction proposal — no significant change in circumstances since then) Issued by: Meg Gruwell, Senior Planner `"�4, The above project has been determined to be exempt from the requirement to obtain a Shoreline Substantial Development Permit based on information from Robert Fritzen, Shoreline Planner with the Department of Ecology, who has stated that demolition of a house does not require a shoreline permit because it is not considered "development", unless some aspect of the proposal is development (such as excavation, digging, etcetera), from a message left on March 3, 2003. This exemption is not being sent to the Department of Ecology because it appears to City staff that it is not subject to U.S. Army Corps of Engineers section 10 permit under the Rivers and Harbors Act of 1899 (the provisions of section 10 of the Rivers and Harbors Act generally apply to any project occurring on or over navigable waters. Specific applicability. information should be obtained from the Corps of Engineers.) Nor does the project appear to City staff to require a section 404 permit under the Federal Water Pollution Control Act of 1972. (The provisions of section 404 of the Federal Water Pollution Control Act generally apply to any project which may involve discharge of dredge or fill material to any water or wetland area. Specific applicability information should be obtained from the Corps of Engineers.) Robert Fritzen has advised us that per WAC 173-27-050, no letter is required to be sent to Department of Ecology. While this letter provides an exemption from the need to obtain a Shoreline Substantial Development Permit from the City of Edmonds, it does not evaluate whether other State and Federal approvals are required and leaves that responsibility to the applicants.. cc: Street file for 15604 — 75"' Place!W. Shoreline Permit Exemption File, i i Page 2 of 2 I xv-- 7/0", 3-10-203 7: 42AN1 I FROe4OL I T I ON MAN 20G7631 6c�0 Paul ihlenes 3201 1' Ave S Suile 209 Seattle, WA 98134 Deer Sir. 0 P. RECEIVED MAR 2 6 L3 BUILDING DEPT. March 8, 2W3 We hope to address the ooncems of the City of Edmonds regarding the demolition of the derelict strictures located at 1b6Q4 75"' PL W. 1. We win install a sit fence per City Of Edmonds E1.2 Starting approximately fifty feet southeast of the shed, then west following the natural contour of the land north to a point frity feet past the abandoned house. 2. We will Build a con ruction road using 4° to 8' screened recycled u mrrete from 7e PL W north to the and of the abanxtonod utility building, and we wiii also build a cxmstruciion road folk7wirlg the. ri ;ww driveway to the lower hatse ondkd the concrete stab bekthe carport. 3. We win use a Komatsu track hoe weighing approxhrrat" forty tour thousand pounds to demolish the Structures. We will use truck,t with end dump trailers to bririp in the material for the constrodlon road and to haul out the Construction debris. The truck and trailer vreigh approx. forty thousand pounds when loaded. 4. Note: all machinery win stay on the construction road and should rat impact sumuunding areas 5. We Plan to wreck the utiirty building first using our track hoe and stotItpiling the material with in the original footprint of the structure. Then we will follow the conatnxtion road to the main house , demolish the house and stockpile the debris on the rarport stab. Next we will start hauling the debris to Waste Management's Eastmont transfer station for disposal. Between loading debris trucks the operator will demolish the shed and stockpile debris for loading. When the strictures have been demolished and removed we will bring in wood chips to fill the basement depression to a slope recommerxiod by a geolechnical "neer. 6. We Propose to access the Property from 76" W to avoid an streets that have weight limits. Sincerely, Joe Murray Demolition Man Inc 20ei-793.0244 THIENES/WILL*VIS ARCHITECTS PLL 3201 First Avenue South #209 Seattle, WA 98134 (206) 623-8733 Fax:(206 3-8760 City of Edmonds, Development Services Department 121 5"' Avenue North Edmonds, WA 98020 Attn: Jeannine Graf, Building Official Re: Stop work information letter 8 Oct `03 Dear Ms Graf. 26 March 2003 1 S 2033 This letter is to acknowledge receipt of this letter by Vivian Bennett and Tommy Fong, present owners, and to make some comments and questions concerning the letter: 1. When the Fongs purchased the property, they had no knowledge of the "Stop Work Order" and further their application for demolition was made with no knowledge of this "Order" and the subject did not come up during the considerable time it took to get their permit. It seems curious that during all the communication with your department this subject did not come up. 2. Your second paragraph indicates that a permit is required to do demolition. We understand this. What is not understandable is your implication that the Fongs are required to demolish the structures..If that is the case will you please supply a copy of the ordinance that requires it. 3. In your third paragraph you state that a new application must be filed by October 22. The Fongs received the letter yesterday. That date is impossible to meet particularly when the necessity for demolition is in question. Nothing in your letter to Aldridge indicates the necessity to demolish the structures; only that a permit is required for demolition. The Fongs are not capable of applying for the permit on their own and I will be out of town until 27 Oct. Clearly your requirements need a professional to perform the application. 4. .I also have trouble understanding the period that the permit the Fongs obtained was valid only until the work cut-off date this year. Usually permits, especially as complicated as that one, are valid for a year. I find no rational reason that the permit should not be valid for another working season. Are you sure you are correct? In conclusion the first step is to show that the Fongs must demolish those structures. We should be provided paperwork showing this requirement. Thank you for assisting us in this matter. Copy: Fong J i Associated Earth Sciences, Inc. M 0 � N U •- January 30, 2003 Project No. KE03034A Vivian Bennett and Tommy Fong c/o Thienes Williams Architects, PLLC 3201 First Avenue South, Suite 209 Seattle, Washington 98134 Attention: Mr. Paul Thienes Subject: Geotechnical Recommendations During Demolition Bennett/Fong Property 15604 75`h Place West Edmonds, Washington Dear Ms. Bennett and Mr. Fong: INTRODUCTION We understand that the current proposal for the subject property is to remove the existing derelict structures (leaving their concrete foundations) to eliminate the liability associated with the "attractive nuisance" of these the structures on the property. This letter summarizes Associated Earth Sciences, Inc.'s (AESI's) recommendations for the proposed demolition. Additionally, recommendations for stabilizing the work areas during demolition activities are provided. AESI completed a geotechnical report for the subject property titled "Subsurface Exploration, Geologic Hazards and Preliminary Geotechnical Engineering Report - Aldridge Short Plat" dated October 24, 1997. A copy of the 1997 report is attached to this letter for reference. SITE DESCRIPTION The subject property is located at 15604 75`h Place West. The approximately 260-foot north - south by 195-foot east -west rectangular -shaped property is bordered on the west by the Burlington Northern Railroad, on the east by 75`h Place West, and on the north and south by single-family homes. Puget Sound is located just west of the Burlington Northern Railroad. The railroad tracks lie approximately 40 feet west of the western property line. ^!M" 9 1 1 Fiff h Avnni ie•, SUi1r 100 • k'irl Lrvl. WA "U"' 2 Phi gin., 4? , R?7-,'701 . f.! F I L E The subject property slopes down from 75'h Place West to the railroad tracks. Three existing structures are located on a gently sloping bench with steep slopes located on the west and to the east. To the west, a steep, approximately 55 percent slope, 40 feet tall, slopes down towards the railroad tracks. Many of the taller trees on this steep western slope are tilted downslope. To the east, a steep, 65 to 75 percent slope rises towards 75' Place West. The slope to the east varies from a few feet high at the south end to 32 feet at the north. - Existing structures on the property consist of a dilapidated house, utility building, and storage shed. The house is a wood -frame, one-story structure with daylight basement and is located on the north side of the property. The utility building is a wood -frame, two-story structure with a crawl space and is located on the south side of the property. The storage shed is located approximately 45 feet west of the utility building. The Meadowdale area, including the subject property, has been identified as an earth subsidence/landslide area. The main Meadowdale landslide likely occurred several thousand years ago. On the subject property there was evidence of subsurface movement that may have occurred as recently as this last winter. This evidence consisted of tension cracks and ground subsidence which were not heavily eroded or overgrown with vegetation. Several previous, regional -scale geotechnical studies have been completed by others to evaluate the landslide hazard potential within the Meadowdale area. In 1979, Roger Lowe Associates, Inc. (Lowe) estimated landslide failure probabilities on a map of the Meadowdale area. At the time of Lowe's report, Lowe estimated that the subject property had a 90 percent chance of landslide movement during a 25-year period. In 1980 through 1985, sanitary sewer, storm sewer, and ground water interceptor drains were installed within landslide areas based on recommendations from Lowe's report. In 1985, GeoEngineers, Inc. revised Lowe's landslide probabilities based on the installation of ground water control improvements. For the subject property, the probability of a landslide occurring in a 25-year period was reduced by GeoEngineers, Inc. from 90 percent to 30 percent. DEMOLITION The existing structures on the property are to be razed in accordance with the "Demolition of Derelict Structures" plan dated January 22, 2003 prepared by Thienes Williams Architects, PLLC. The three existing structures on the property will be removed to the -concrete foundation. All depressions resulting from removal of the structures should be backfilled. Demolition of the existing structures should have a low impact on the stability of the western slope provided the recommendations contained herein are followed. AESI recommends backfilling the basement with a low -weight backfill material such as wood chips (aka "hog fuel"). This material will eliminate the safety hazard by filling the basement depression, is light 'weight, and can easily be removed and reused (in landscape areas) following development of the property. 2 STABILIZATION OF WORK AREAS During demolition activities we recommend the contractor adhere to the following recommendations. 1. Placement of 2-inch or larger crushed rock as necessary for construction equipment access to avoid tracking soil onto adjacent streets. 2. Once existing structures have been demolished, all exposed ground surfaces should be seeded and mulched with a suitable seed/mulch erosion control mixture. 3. All work should be confined to the immediate vicinity of the structures and access road. 4. Additional measures, such as silt fences, should be employed as necessary to prevent off -site sediment transport. We have enjoyed working with you on this study and are .confident that the recommendations presented in this report will aid in the successful completion of your project. If you should have any questions or if we can be of additional help to you, we are here to assist you. Sincerely, ASSOCIATED EARTH SCIENCES, INC. Kirkland, Washington Bruce L. Blyton, P.E. Principal Engineer Attachment: 1997 Geotechnical Engineering Report BLB/Id KE03034A1 Projectt\2003034A\KW\WP. W2K 3 • CITY OF EDMONDS 121 5TH AVENUE NORTH - EDMONDS, WA 98020 - (425) 771-0220 • FAX (425) 771.0221 DEVELOPMENT SERVICES DEPARTMENT Ih c 1 gcj0 Planning . Building - Engineering August 28, 2000 Robert Hughes Reed and Associates, PS 8311 212th Street SW Edmonds, WA 98026 SUBJECT: Aldridge Single Family Residence at 15604=751h,Place West'(I!C#-99-044) Dear Mr. Hughes, GARY HAAKENSON MAYOR, In an earlier discussion with Theresa Aldridge, she asked if we would allow two grinder pump systems to be tied into one sewer lateral. She was advised that the Public Works Department will not allow it, and that each house must have a separate side sewer line. During my review of the subject application, the drawings indicate the two systems tied into one lateral. Since we do not allow that arrangement, two separate lines will have to be installed. After reading the Geo-Technical Engineer's recommendation not to disturb the slope west of 75`h Place West, I am recommending the two systems tie into ssmh #63 (south of short plat entrance) above the existing 8" line. Listed below are areas of concern that need to be addressed before I can complete the review of this application. Please submit 3 copies of the new drawings to the Development Services Coordinator. 1. Show location and connection of the 2 new grinder pump lines to ssmh #63. 2. Place note on drawing to cap old side sewer. 3. Driveway width on "Typical Driveway Section" should be 12.00' between curbs. 4. Change note on Sanitary Sewer Cleanout Detail to reflect separate lines and show connection to ssmh #63 (if this option is taken). 5. Pipe anchor details do not match details submitted and approved by BNSF. Please make changes to reflect approved anchor system. 6. Indicate water meter locations for both lots (per short plat requirements). Water lines should be under driveway and separated from the sewer line by 10'. 7. Show location of other utilities to avoid conflicts. If you have any questions, please call me at 425-771-0220, Ext. 1324. Sincerely, 4G� LYLE CMUSMAN Development Services Engineer ALC/cmc c: Marie Harrison, Development Services Permit Coordinator • Incorporated August 11, 1890 G: \ENGRU.YLE\developmrnt-review\bldgyermit\99-441tr.doc Sister City - Hekinan, Japan Ij7 c 18g0 CITY OF EDMONDS 121 5TH AVENUE NORTH • EDMONDS, WA 98020 • (425) 771-0220 • FAX (425) 771.0221 DEVELOPMENT SERVICES DEPARTMENT Planning • Building • Engineering April 10, 2000 Reed and Associates, PS 8311 - 212'' Street SW Edmonds, WA 98026 Attn: Robert Hughes SUBJECT: Theresa Aldridge Residence (,PC-99-441 Dear Mr.. Hughes, GARY HAAKENSON MAYOR I discussed .your March 24 letter with the City Engineer, Jim Walker. The following comments and clarifications result from that discussion. I duly note your items 1, 2 and 3 and expect to see them placed on the final plans for construction approval. There remains some question or need for clarification regarding your item 4. The City has every intention of constructing a pedestrian path or walkway on the west side of 75' Place West, and the proposed wall cannot infringe upon the potential sidewalk location. Rather than a maintenance agreement for your item 5, the City wants Ms. Aldridge to obtain an Encroachment Permit for any rockery or wall within the public night -of -way - To better allow for future sidewalk construction, the City Engineer feels that the convergence of the driveway and the roadway can be better designed. You are correct in item 6 that the existing situation is "grandfathered-in". However, that existing condition rule only applies for the single-family residence. Your client also applied for .a subdivision. The Engineering Division staff. can approve the existing condition for the single-family permit, but the City Engineer may require that the access be revised prior to approval for the subdivision. I trust this clarifies any confusion that may arise. If you have any questions, please do not hesitate to contact the Jim Walker at (425) 771-0220 or me at (425) 77.5-7744 at your convenience. Sincerely, GORDON HYDE Development Services Engineer GCH/cmc R: \ENGR\GORDY\eldridgesfr. DOC • Incorporated August 11, 1890 • Sister Citv - Hekinan. Japan i ASSOCItORPQRATE OFFICE RECEIVES 911 FA Avenue, suite 100 ARTj" Kirkland, Washington 98033 ,�&TIE(425) 827-7701 SCIENCES, MC FEB 18 2000 FAX (425) 827.5)124 REED & ASSOCIATES i ruaiy 15, 2000 Project No. KE97224A FILE Theresa Aldridge 8311 212"' Street SW Edmonds, WA 98026 Subject: Geotechnical Plan Review and Response Aldridge Single Family Residence Edmonds, Washington BAINBRIDGE ISLAND OFFICE 179 Madrane Lane North Bainbridge Island, WA 98110 (2061780.9370 FAX (2061 750.9438 VL� I,'' a R Z7' DEVELOPMUIT SERVICES CTR. CITY OF EDMoi4ll5 Reference: 1) Proposed Aldridge SFR, Cylinder Pile Retaining Wall, February 1, 2000 Landau Associates. 2) Geotechnical Report, January 18, 2000, Associated Earth Sciences, Inc. 3) Site Plan, Sheet 2, revised January 7, 2000, Terrence C. Watson Architect. Dear Ms. Aldridge: Associated Earth Sciences, Inc. (AF,SI) has reviewed the February 1, 2000 letter by the City of Edmonds geotechnical consultant Landau Associates. In response, AESI has reviewed the structural engineering design and has provided additional geotechnical comments regarding the proposed cylinder pile wall. The reviewed referenced plans and structural design for the cylinder pile wall are in conformance to AESI's geotechnical recommendations, The geotechnical declaration and statement of risk provided in AESI's letter dated February 23, 1999 is still applicable to the project as designed. In AESI's opinion, the construction of the wall will provide a factor of safety of at least 1.25 under static loading. In addition, it is AESI's opinion that following construction of the wall as designed, the risk of slope movement within a 25-year period is less than 30 percent, OCEIVED If you have any questions, please do not Hesitate to call, Sincerely, ASSOCIA'iCED EARTH SCIENCES, INC. Kirkland, Washington Joseph B. Clare, E,I.T. Senior Staff Engineer cc: Robert Hughes, Landau Associates City of Edmonds, Jeannine Graf Landau Associates, Edward Heavey nuapi kC97224a8 Id • d;\jI11244 - vr2k FEB 18 2000 REED & ASSOCIATES EXPIRES Bruce L. Blyton, P.E. Senior Associate Engineer 0) RECEIVED CORPORATE OFFICE ASSOCIATED 911 Fifth Avenue, Suite too EARTH ,JAN 1 $ 2000 Kirkland, Washington 90033 (425) 827-7701 SCIENCES, INC FAX (425) 827-5424 BAINBRIDOE ISLAND OFFICE 179 Madrone Lune North Bainbridge kdond, WA 9811 D January 18, 2000 (206) 780-9370 Project No. KE97224A FAX (206) 780-9458 Reed and Associates 8311 - 212" Street SW Edmonds, Washington 98026 Attention: Robert Hughes Subject: Cylinder Pile Retaining Wall Aldridge Single -Fan -Lily Residence 15604 -- 75`t' Place West Edmonds, Washington Reference: City of Edmonds Response Letter by Jearuune L. Graf, October 27, 1999 Tear Mr. Hughes: RECEIVED JAN 2 0. MOO DEVELOPMENT CTR. CITY OF EDMONDS CI'TY COPY Associated Earth Sciences, Inc, (AESI) has completed additional geotechnical study with regards to the design and installation of a cylinder pile wall for the Aldridge property, Our scope of work included evaluating ground water conditions on the property, computer slope stability . modeling, and developing geotechnical design parameters and installation recommendations for the retaining structure. BACKGROUND In reference to the above; City of Edmonds letter dated October 27, 1999, to satisfy the: requirements set forth by the City, the owner has chosen to proceed with the design and installation of a retaining structure. This structure is intended to mitigate against landslide hazard for both proposed north and south lots of the Aldridge short plat. SITE CONDI'T'IONS Since AESI's initial geotechnical report dated October 1997, additional geotechnical field study has included the monitoring of slope inclinometers, the installation of two shallow ground water monitoring standpipes, and surface reconnaissance. Additional geotecluucal analyses performed included computer stability modeling of the existing and proposed post -construction conditions of the property. Based on the installation of two ground water standpipes, ground water has been observed at shallow depths ranging between 2 and 3 feet below ground surface. The two standpipes were hand installed and located within the western end of the northern half of the property (near the top of tho western slope). Ground water observations were 'niade on December 14, 1999 at a time of extended wet weather. Due to the fractured and non -homogenous soil texture, the presence of ground water is expected to vary with location. The impacts of a, high ground water table have been considered in the design of the wall and in home construction. Proposed deep excavation for the basement of the home and the installation of foundation wall drainage will intercept a portion of Ehe shallow ground water observed on -site. No deep ground water was observed within our initial geotecluiical exploration borings and the shallow ground water on -site has been interpreted as seasonal perched ground water. The movement of the water through the silt and clay will be through fractures and sand lenses in contrast to movement throughout the soil unit. Additional field reconnaissance has not shown an appreciable change in the surface topography of the site. since AESI's original study in late 1997. However, slight soil movement has been measured in the two slope inclinometers as reported in AESI's July 22, 1999 letter. MAINING WALL As .currently proposed, the retaining structure consists of a cylinder pile wall, This wall consists of closely spaced, reinforced concrete soldier piles. Since timber lagging is not used between the piles, the edge -to -edge pile spacing is designed to utilize soil arching for lateral restraint of the retained soil. The soldier piles will be completed below grade and located near the top of the western slope. The wall will extend from the northern property line to within about 50 feet of the southern property line. Piles will consist of 247inch-diameter augered holes filled with concrete. Per the structural engineer's design, W16 x 89 steel beams will extend the full depth of the augered holes and spaced on 6-foot centers (4 feet edge to edge). The piles will be embedded a minimum of 20 feet into bearing soils (Double Bluff Drift) with about 1.3 -feet of retained soil. Final pile locations may be field adjusted to minimize impacts to the slope. The recommended lateral earth pressure for the upper 13 feet of retained soil (slide debris/Possession Drift) is 117 pounds per cubic foot (pct) equivalent fluid, acting over the 6- foot pile spacing. This value includes saturated soil forces with sloping topography behind the wall. An equivalent fluid of 67 pcf acting over one pile diameter (2 feet) should be used within the bearing soils below 13 feet depth (Double bluff Drift). A passive resistance of 400 pcf equivalent fluid should be used for the lower 20 feet (Double Bluff Drift) of the downslope end of the pile. The passive resistance acts over two pile diameters (4 feet). Computer modeling of slope stability demonstrates an increase in, the factor of safety following construction of the soldier pile wall. The computer model was developed such that the existing slope and geologic conditions provided a factor of safety equal to 1. The impact of a high 2 N ground water table was included in the model. Following construction of the wall, the factor of safety increases, to 1.15 under static (non -seismic) conditions and assuming no decrease in the ground water level on the property. Under seismic conditions, a factor of safety of < I was modeled, indicating that a large earthquake (greater than TO magnitude, 0.2g horizontal acceleration) would likely result in wall damage. Additional reinforcement of the slope will be realized following excavation and installation of home foundation piles, but this benefit was not relied upon in the computer model. During the design life of the wall, downslope soil movement may occur on the west side of the wall (downslope). If erosion between the individual piles occurs, ti nber or concrete lagging can be installed to shore the upslope soils. INSTALLATION RECOMMENDATIONS AESI should be on -site during pile installation to verify that construction is in accordance to the approved plans and specifications. The AESI field representative will document individual pile depths, embedment, and verify that subsurface conditions are consistent with the design. CONCLUSIONS In our opinion, the construction of the soldier pile wall is a suitable mitigation for the potential of shallow earth movement on the property. The impacts of a high ground water table have been considered in die design of the wall and in .home construction, Should you have any questions, or require further assistance, please do not hesitate to call. Sincerely, ASSOCIATED EARTH SCIENCES, INC. Kirkland, Washington os�eph E. Clare, E.I.T. Senior Staff Geotech.n.ical Engineer cc: Theresa Aldridge 18330 Olympic View Drive Edmonds, Washington 98020 PiChl .100224A7 - LD-DAIMI-00 • W2K WAS �� oY " rr Bruce L. Blyton, P.E. Senior Associate Engineer 3 NY-1-1 ;WS C4 zLzb-99G (90z) Mid W--CL9 (OV) -H �G— =W LG c-G9G (9oc) GG LgGbi L"'911H9NV WO.1 glt=199W WIN .j w am 0 U) Fu to t2 W c:c air cc LLJ o. nn Es 01 Ig RR o 99 U, t fli 4.s= w !'6E .1b .6 4 .1fe LLN — illivi� X, ---------- ------ AM, --------------- ------- ---- -------- --------------- ----------------- --- --------- ------------------- ----------- ------------------- N -------------------- -------------------- -------------- ------------------ ----------------- -------- -- ----------- ---------- -:-:-: -- ------------- --- ---------- ------------ ---------- --- . . . . . . . . ---------------- ---- ----- ----------------- -------- --------- ------ ----- - -- - ---------- -- - ------------ ----------------- ----- ----------------- -------- ---------- -- ----------- ---------------------------- ---------- - - ------ --------------- --- --------- --- - --- - ---------- ------- - --- -------- -- ------------------------------ - ---------------- -- ----------------- --- ---- -------------------------- -------------- ------ -------------------------- G -9v ,1 -1 --- G-VG N617fff JO N NO 19 Ni�2i no W vp j P iWN I \C# @6pijp[v esajaql - HB6\B66j\sqor\:0 9V :01 :9; 00;1L01;0 6MP'3AS-20-H96 HEY CITY OF EDMONDS BARBARA MA MAYOR 121 5TH AVENUE NORTH • EDMONDS, WA 98020 • (425) 771.0220 • FAX (425) 771.0221 DEVELOPMENT SERVICES DEPARTMENT j 0 Planning • Building • Engineering nc.189 October 27, 1999 Mr. Robert J. Hughes Reed & Associates, PS 8311 212th Street Southwest Edmonds, Washington 98026 RE: Aldridge SFR @ 15604 75`h Place West, Plan Check #99-44 This letter is in response to your October 18, 1999 letter, and also includes my comments regarding the Associated Earth Sciences, Inc., (AESI) Technical Memorandum of October 8, 1999. As you are aware, outside geotechnical consultant review is required to demonstrate compliance with the Meadowdale Ordinance. It is expected that the review will also demonstrate that the submittal meets accepted engineering practices in effect at the time of the submittal. This is an important distinction, since our understanding of the Meadowdale landslide, and of general geologic conditions within the City, is constantly evolving, whereas the Ordinance is not regularly updated. As Building Official for the City, it is my job to ensure that submittals meet both of these objectives, and advise the Council if, in my opinion, the Ordinance needs revision. With this in mind, I have reviewed the application and have made several conclusions and determinations. First, for new construction and significant remodels within the Meadowdale landslide boundary, submittals must include feasible attendant measures and improvements to minimize the potential of earth movement anywhere on the site, prevent avoidable damage to structures, safeguard adjacent properties, and limit risk to inhabitants. The geotechnical report must provide subsurface data to support the engineers conclusions regarding slope stability and all forms of potential future earth movement (e.g. slumps, debris avalanches, earth flows, debris falls, mud flows, deep rotational failures, and complex landslides involving several forms of movement): While the Ordinance does not require an applicant to stabilize potential deep-seated landslide movement (of the type that impacts several parcels), it is expected that such potential movement will be clearly described in the geotechnical report. This is so the original design team/owner, and all future owners, will be aware of the risks associated with living in the Meadowdale landslide area. It is required that shallow movement on individual parcels be addressed through engineering controls and best available science to eliminate the threat of such movement, to the degree possible. • Incorporated August 11., 1890 • Sister City - Hekinan, Japan t Mr. Hughes October 27, 1999 Page Two In the AESI original 1997 report they conclude that the site is buildable, but note that future inclinometer and groundwater monitoring may effect that conclusion. Landau Associates review of the 1997 report identified concerns about slope stability, .and pointed out that supplemental data had not been submitted with the application. Landau Associates identified additional issues, but my review indicates that those items have been addressed. The AESI July 1999 response letter describes shallow and deep landslide hazards. The discussion on shallow landsliding focuses on the east and west slopes, but does not address the mechanism(s) causing the sliding, particularly of the "bench" where the proposed home will be located. A description of groundwater conditions, and the relationship between groundwater and soil movement, is noticeably absent (even though AESI's original scope of services included groundwater as a key study element). Inclinometer data submitted with the report indicates the upper 10 to 15 feet of the site has undergone movement over the past two winters. This data, plus City staff and professional consultant observations of fresh ground cracks at the site during the 1996/97 winter, and past history of sliding at the site reported by others, leads to my determination that near -surface soil at the site is not stable under current Ordinance definitions. The last letter does not specify what choices for stabilization have been made and does not address current movement. The owner must decide from the geotechnical evaluation which measures are to be provided for stabilization. The geotechnical engineer must then evaluate the potential of the attendant measures to stabilize the movement over the 25 year period. As for deep-seated landslide potential, the AESI response indicates a low to moderate hazard. It has been called to my attention that one. of the two inclinometers is set with its base at the projected slide zone, and question whether accurate data can be collected from that location. It has also been called to my attention that no groundwater data is presented to support AESI's conclusions about deep landslide hazards. However, since movement on the deeper slide plane would likely affect several properties, and since the inclinometer data does not suggest movement is occurring along the deeper slide plane, I have concluded that AESI's statement of risk, as it pertains to deep-seated landsliding, is currently acceptable. I have concluded that supporting the proposed house. on piles is an acceptable means of addressing foundation concerns, and site stability, in the immediate vicinity of the home. I have also concluded that simply removing several feet of soil from atop the west slope in front of the home is not adequate to stabilize the rest of the site, based on the absence of a stability analysis verifying that this approach will work. One of my concerns is that this soil may be acting as a buttress, and that by removing it you may actually accelerate landslide movement. Page 9 of AESI's original report states that slope stability modeling can be done during the design phase of the project, but to my knowledge this has not been performed. Mr. Hughes October 27, 1999 Page Three Concerning the AESI Technical Memo dated October 8. 1999. AESI does not mention the September 28, 1999 Review Status letter by Landau Associates; therefore, it is not clear whether their memo is of a general nature, or intended to address the Landau comments. In any event, and as stated above, I have determined that the site is not stable and will likely not be stabilized by the means recommended to date. Alternatives available to you at this time appear to include: 1) Withdraw the permit application. 2) Perform additional testing, including, but not limited to, groundwater monitoring, additional inclinometer readings and slope stability analysis, to demonstrate that the proposed construction will, a) halt the seasonal movement which appears to be occurring, and b) lower site risks to the level required by the Ordinance. Such testing must also include a post -construction compliance component, to demonstrate that the site has been stabilized. Once geotechnical study and evaluation is complete recommendations to the owner must be presented. The homeowner must decide which measures to implement. The geotechnical engineer must then evaluate the improvements to stabilize the documented earth movement over the 25 year period. Construction techniques and phasing of specific improvements must be specifically addressed. The geotechnical engineer must then address anticipated conditions after the improvements are installed including movement on the site. 3) Design and construct a retaining structure atop the west slope, similar to, what has been approved for the neighboring parcel to the north. Additional investigations may be needed for this structure, and I anticipate that a stability analysis will also be required. If you will be pursuing this approach, please contact me before beginning design efforts. Please contact me if you have any questions concerning the contents of this letter. Thank you, �rOW4� Jeannine L. Graf Building Official, C.B.O. cc: Theresa Aldridge, Owner Bruce L. Blyton, P.E., AESI Landau Associates ' o f EQ4 `y G CITY OF EDMONDS 121 5TH AVENUE NORTH • EDMONDS • WA 98020 • (425) 771-0220 http://www.ci.edmonds.wa.us RCW 197-11-970 Determination of Nonsignificance (DNS) DETERMINATION OF NONSIGNIFICANCE Description of proposal: Construction of a 5,000 square foot, Single Family Residence within a designated Environmentally Sensitive Area for Steep Slopes and the Meadowdale Landslide Hazard Area. Application includes 1,957 cubic yards of excavation. Proponent: Theresa Aldridge Location of proposal, including street address if any: 15604 75d, Place West Lead agency: CITY OF EDMONDS The lead agency for this proposal has determined that it does not have a probable significant adverse impact on the environment. An environmental impact statement is not required under RCW 43.21.030(2)(c). This decision was made after review of a completed environmental checklist and other information on file with the lead agency. This information is available to the public on request. . XX There is no comment period for this DNS. • This DNS is issued under 197-11-340(2); the lead agency will not act on this proposal for 14 days from the date below. Comments must be submitted by 11999. • Responsible Official: Jeffrey S. Wilson A.I.C.P. Position/Title: Planning Supervisor Phone: 425-771-0220 Address: City of Edmonds, 121 5th Avenue North, Edmonds, WA 98020 Date: Signature: XX You may appeal this determination to Robert Chave, Planning Manager, at 121 5th Avenue North, Edmonds, WA 98020, no later than JLLne 7S , 1999, by filing a written appeal citing the factual reasons for the appeal. The appeal submittal must also include the required fees and mailing list. Please contact the Planning Division for specific submittal requirements. You should be prepared to make specific factual objections. Contact Jeffrey S. Wilson to read or ask about the procedures for SEPA appeals. XX Posted on `lam 1 �" , 1999, at the Edmonds Public Library, Edmonds Community Services Building, and the Edmonds Post Office. XX Distribute to "Checked" Agencies on the reverse side of this form, along with a copy of the Checklist. Page 1 of 3 PLCK 99-44 DNS. DOC CREATED ON 06/10/99 4:25 PM Mailed to the following along with the Environmental Checklist: XX Environmental Review Section XX • Department of Ecology P.O. Box 47703 Olympia, WA 98504-7703 XX XX Department of Fisheries Attn.: Richard E. Johnson Regional Habitat Manger 16018 Mill Creek Boulevard XX Mill Creek, WA 98012 XX Department of Wildlife 16018 Mill Creek Boulevard Mill Creek, WA 98012 i I Attachments pc: File No. Pt -k a9-44 SEPA Notebook i I I � II I j Page 2 of 3 PLCK 99-44 DNS. DOC CREATED ON 06/10/99 4:25 PM Iij Burlington Northem-Santa Fe Railroad 2900 Bond Everett, WA 98201 Theresa Aldridge 18330 Olympic View Drive Edmonds, WA 98020 Robert Hughes 144 Railroad Ave #206 Edmonds, WA 98020 • • Date: To: From: Via: MEMORANDUM June 10, 1999 Plan Check File No. 99-44 Karissa Kawamoto, Planner Jeffrey S. Wilson, Responsible Official Subject: ENVIRONMENTAL DETERMINATION FOR A PROPOSED 5,000 SQUARE FOOT SINGLE FAMILY RESIDENCE LOCATED WITHIN THE ENVIRONMENTALLY SENSITIVE AREA FOR STEEP SLOPES AND THE MEADOWDALE LANDSLIDE HAZARD AREA. SITE ADDRESS IS 15604 75T" PLACE WEST. I have had the opportunity to field check the site, review the Building permit application and environmental checklist which have been provided for the proposal. A survey and geotechnical report has been submitted and reviewed by Landau and Associates for compliance with the Meadowdale Earth Subsidence requirements. Final details are yet to be worked out, but the house location most likely will not be moving.. The applicant has also indicated approximately 1,957 cubic yards of excacation will be required for construction of the home and driveway. Based on my review of all available information, analysis of the project proposal by licensed professionals. for adequacy, and adopted policies of the City, I recommend that a determination of nonsignificance be issued for the project. Review by Responsible Official I concur: I do not concur: Jeffrey S. Wilson A.I.C.P. Date PLCK 99-44.SEPA.DOC 06/ 10/99. City of Edmonds cQ Planning Division 16. 009-000-001-0207 Degan, Thomas and Marilyn 15570- 75 PI.W. Edmonds, WA 98026 5009-000-001-0306 Mezich, Rick and Mary 7215-156 St. SW Edmonds, WA 98026 5009-000-003-0205 Namkung, Yong and Keesoon 15516- 72 Ave. W. Edmonds, WA 98026 5131-028-001-0001 Schluter, Ursula 15620 -75 P1.W Edmonds, WA 98026 131-028-005-0106 W570ell, Harrison 6 -75 PI.W. Edmonds, WA 98026 5131-000-024-0102 Hansen, Sott and Tiffany 15615 - 75 P1.W. Edmonds, WA 98026 5131-000-024-0201 Maden, Richard and Linda 15625- 75 PI.W. Edmonds, WA 9026 5131-000-024-0409 Andahl, Alice 15605 - 75 PI.W. Edmonds, WA 98026 5131-000-025-0109 Rusnak, Michael and Betty Od620 - 75 PI.W. monds, WA 98026 5133-000-025-0208 Caryl, DH 15701 - 75 PI.W. Edmonds, WA 98026 5133-000-025-0307 Spiro, Joanne 15631 - 75 PI.W. Edmonds, WA 98026 5133-000-027-0008 Nelson, Norman and Doris 15729 - 75 PI.W. Edmonds, WA 98026 5009-000-001-0108 Chynoweth, Vic and Nancy PO Box 213 Warner Springs, CA 92086 5009-000-001-0306 Miller, Kenneth 19911- 89 PI.W. Edmonds, WA 98026 5131-028-003-0009 Lantz, R.Michael Jr. 18225 - 47 Pl. N.E. Seattle, WA 98155 Theresa Aldridge 18330 Olympic View Dr. Edmonds, WA 98020 Robert Hughes 144 Railrqpd Ave. #206 Edmonds, WA 98020 Vacant lot N of 15605- 75 P1.W. Blk 000 D-0 of 01 Less th ptn LY W oM LN of exist RD Vacant lot N of 15570- 75 P1.W. Blk 000 D-0 th P TN Lot 4 LY W of W Exist RD, Also N ]OF L t l LY W of Exist RD Vacant ;7_00- f 15620 - 75 P1.W. -�-- Blk 02Lots 3and 4 Plus Vac ST CORPORATE OFFICE ASSOCIATED 911 Fihh Avenue, site too EARTH Kirkland, Washington 98033 JEMSCIENCES, IIVC 827-7701 FAX )(425)827,5424 February 23, 1999 Project No. KE97224A Theresa Aldridge 18330 Olympic View Drive Edmonds, Washington 98020 Subject: Geotechnical Plan Review Aldridge Residence 15604 75' Place West Edmonds, Washington Dear Mrs. Aldridge: BAINBRIDGE ISLAND OFFICE 179 Madrone Lane North Bainbridge Island, WA 98110 (206) 780-9370 FAX (206) 780-9438 As requested, Associated Earth Sciences, Inc. (AESI) performed a geotechnical review of the plans for the proposed Aldridge Residence within the Meadowdale area of Edmonds, Washington. In addition, as requested by the project engineer representative, Robert Hughes of Reed and Associates, we have provided a generalized construction sequence, verified augercast pile capacity, and reviewed the proposed drainage plan. This letter also provides a statement and declaration of risk as required by the City of Edmonds for development within the Meadowdale area. EROSION CONTROL AND STORMWATER DRAINAGE PLANS The erosion control and drainage plans were prepared by CG Engineering, referenced as Aldridge Residence, sheets C1.1, C2.1, and C2.2 and dated May 28, 1997. In our opinion, the following changes should be made: • Sheet C 1.1 Detail 2: Minimum of 8-inch thickness of 4- to 6-inch quarry spalls over fabric (Amoco 2002 or equal). • Sheet C 1.1: Construction Sequence: Delete repeated line 7. • Sheet CIA: Erosion Control Notes: Hydroseeding, vegetation, sod should be planted by September 15. • Sheet C2.2 Detail 4: Provide for clean out of perforated dispersal pipe. • Sheet C2.1 Construction Notes 11: 4-inch dia., rigid, perforated PVC pipe. • Sheet C2.1 Construction. Notes 12: 4-inch dia. PVC tightline from 4-inch dia. rigid, perforated PVC foundation and rockery drains. r� J In our opinion, due to the existing geologic conditions, the use of a storm water dispersal system, as designed and approved by Burlington Northern Railroad, is preferred over a buried or surface mounted detention system located near the top of the western slope. FOUNDATION AND STRUCTURAL PLANS The architectural and structural plans were prepared by Terrence C. Watson, referenced as Aldridge Residence, sheets 1 through 9, and 11 through 19, sheet 10 not used, and dated February 4, 1998. In our opinion, the following changes should be made: • Sheet 1 General Structural Notes, Foundations: Extend piers into bearing strata per on site geotechnical engineer. Fourteen feet minimum into bearing strata. • Sheets 16 and 17: Drain pipe for grade beams, foundation/retaining wails to consist of 4-inch diameter, rigid, perforated PVC pipe. Drain pipe should be surrounded by a minimum of 8 inches of washed drain rock. • Sheets 16 and 17: Minimum 4-inch thickness of washed pea gravel capillary break beneath floor slabs. Plastic vapor barrier where required. GENERALIZED CONSTRUCTION SEQUENCE 1. Install and inspect TESC measures (late winter). 2. Demolish existing structures (late winter/early spring). 3. Hydroseed disturbed areas outside development area. Protect other areas per TESC plan (late winter/early spring). 4. Excavate home foundation area (early spring). 5. Install drainage measures (early spring). 6. Install foundation elements (spring). 7. Construct home, backfill foundation elements, and finish grade site (summer). 8. Plant temporary and/or permanent vegetation by September 15. 9. All site earthwork to be completed by October 1. 10. Establish Landscaping and permanent vegetation (fall or spring). 2 i • ft AUGERCAST PILE CONSIDERATIONS Augercast piles 16 inches in diameter are proposed for foundation support. To provide the required allowable 20-ton vertical capacity, we estimate that piles will be on the order of 26 to 31 feet in length. A minimum embedment of 14 feet into the bearing strata will be required. GEOTECHNICAL DECLARATION AND STATEMENT OF RISK In our judgement, the plans and specifications prepared by the structural engineer conform to the recommendations in the geotechnical report provided that the above revisions are made. The risk of damage to the proposed development, or to adjacent properties, from soil instability will be minimal, subject to the conditions set forth in the report. The proposed development will not increase the potential for soil movement. Based on the proposed drainage and grading mitigations as described in our report, as specified on the plans, and as presented in published geologic literature, we estimate that the site is susceptible to a 30 percent probability of earth movement within a 25-year period. With the above revisions, the plans reviewed by us conform to the recommendations in AESI's Subsurface Exploration, Geologic Hazards, and Preliminary Geotechnical Report, dated October 24, 1997. If you should have any questions or if we can be of additional help to you, please call. Sincerely, ASSOCIATED EARTH SCIENCES, INC. Kirkland, Washington J Joseph B. Clare, E.I.T. Senior Staff Geotechnical Engineer CC: Robert Hughes Reed & Associates 144 Railroad Avenue, Suite 206 Edmonds, WA 98020 JEC/mb - KE97224A2 - 2/20199 mb - W97 ' JCS B L was�,�ti,,0�'L �Jy�l9q ieAoO A,. EXFIR'cS S l 31 r7 Bruce L. Blyton, P.E. Senior Associate Engineer 3 CITY OF EDMO1VDS BARBARA FAHEY 121 5TH AVENUE NORTH - EDMONDS, WA 98020 - (425) 771-0220 - FAX (425) 771-0221 MAYOR COMMUNITY SERVICES DEPARTMENT Public Works • Planning/Building • Parks and Recreation • Engineering • Wastewater Treatment Plant Theresa J. Aldridge April 28, 1998 18330, Olympic View Drive Edmonds, Washington 98020 RE: 15604 75d' Place West, Edmonds The purpose of this letter is to notify you that a "Stop Work" Order has been placed at property you own at 15604 75`h Place West, (ownership verified by Snohomish County Assessor's office). The stop work_ was placed because demolition work had commenced on buildings without the required demolition permit(s). This is a violation of Section 106 of the 1994.Uniform Building Code and Edmonds Community Development Code (ECDC) Chapter 19.05 and is subject to penalties as outlined in ECDC 19.00.080 and ECDC 20.110. As you know from your meeting on 1/22/98 with City Officials, the property is located in the designated Meadowdale Earth Subsidence Area and is subject to strict development requirements of ECDC Chapter 19.05. Therefore, the stop work shall remain in. force until a demolition permit is issued by the Building Official. Please be advised, the typical Meadowdale permit process is six months to one year to obtain permits and groundwork is limited from May 0 to September 30th. In order for the demolition permit to be issued at a minimum, the City shall require that you enlist the services of a licensed professional geotechnical engineer to provide a detailed report as outlined in the Meadowdale packet. This report shall be reviewed by third party review and full review fees are paid by the applicant. A demolition plan shall also be required that details existing structures to be removed and provides temporary and permanent slope protection or site restoration in accordance with the geotechnical engineers' recommendations. Note, double permit fees and investigation fees will be assessed upon permit issuance since work started prior to permit issuance. Our records indicate that you have already purchased a Meadowdale Earth Subsidence packet and we recommend that you provide a copy to your geotechnical engineer for review. To. reiterate no work that requires a permit shall continue at 15604'75`h Place West, Edmonds, until further notice from the Building Official. On a sidenote, Jim Waite, Water/Sewer Supervisor has informed me that a City maintained grinder pump is located on site. He would like the opportunity to remove it at your earliest convenience, please call him at 425-771-0235 extension 649. If you have any questions please feel free to contact me at 425-771-0220. Thank you, 464�f )—�) Jeannine L. Graf Building Official • Incorporated August 11, 1890 • Sister Cities International — Hekinan, Japan 0 . 6 By order of the Building Official for the City of Edmonds All Persons Are Ordered to STOP WORK AT ONCE Pursuant to Section 202(d) of the Uniform Building Code the Building Official for the City of Edmonds hereby orders all work to STOP at the site listed below. Address: For the following reason(s): WARNING T Posted this day of The failure to stop work, or the at 3• a� Elm Building Official resuming of work without permis- sion from the Building Official, or the removal, mutilation, or concealment of this notice is punishable by fine and imprison-. ment. N 0 . 0 CITY OF EDMONDS 250 - 5TH AVE. N. • EDMONDS, WA 98020 • (206) 771-0220 • FAX (206) 771-0221 COMMUNITY SERVICES DEPARTMENT Public Works • Planning • Parks and Recreation • Engineering 89p . 19y September 26, 1995 Ms. Ann Kivimaki 17630 18th Avenue West Lynnwood, Washington 98037 RE: Torkjel Carlson Property @ 15604 75th Place West LAURA M. HALL MAYOR The City is in receipt of the AGRA soil reconnaissance report dated 9/21/95 for the subject site. The City shall impose the recommendations for erosion control as described within the report and pursuant to the Meadowdale Earth Subsidence Ordinance the work shall be completed by October 15th, 1995, If some unforeseen event prevents you from completing the work by the established deadline you must immediately notify the City. Enclosed is a permit application for the demolition of the shed structure. Please complete the form and return it to the City with permit fees of $30.00. The required work as described by AGRA is as follows: 1. The ramped slope must be track -walked upslope and downslope to provide ridges to interrupt runoff sheet flow. 2. The final grading should be 3:1 with ruts or depressions removed. 3. The slope area must be hydroseeded and maintained until vegetation becomes established. 4. Protection of new vegetation shall be protected with visqueen or erosion control fabric until the vegetation becomes established. 5. If the ramp slope will be continued to be used for construction activities the slope shall be covered with quarry spall rock of 2 to 4 inch size. If no further work will be done in this area, revegetation with hydroseeding, is required. If you have any questions regarding the recommendations of the report you should contact your engineer for clarification. Please call me at 771-0220 when the work is complete. Thank you, (*AW Jeannine L. Graf Building Official cc: AGRA Kurt D. Merriman, P.E. • Incorporated August 11, 1890 • Sister Cities International — Hekinan, Japan 1 FROM.: KIVIMAKI# TAD/FAX • PHONE NO. : +206 743 3109 Sep. 25 1995 03:25PM P1 0AGRA. Earth & Environmental 21 September 1995 11-10620-00 Ann Kivimaki 17630 lath Avenue Wast Lynnwood, Washington 98037 Attention: Subject: Ms. Kivimaki: Ms. Ann Kivimakl AGRA Earth & Environmental, Inc. 11335 NE 122nd way Suite 100 Kirkland, Washington U.S-A, 98034•0918 Tal (206) 820.4660 r � Fax (206) $21.3914 Erosion Control Recommendations 15604 75th Piece West Edmonds, Washington ., t, This letter presents the rests of a visual slope reconnaissance and recommendations on the above rs eferenced ite. The.property is located at 16604 76th place West in the Meadow.dele area of Rdmonds, immediately north of new construction for a residence. We visited the site on 16 September 1995 and met with the property owner Ms. Ann Kivimaki. According to Ms. KhAmakl, the owner of the parcel to the south wee given permission to use the gravel driveway for access to construct the new house. We understand an abandoned shed, on the order of 20 feet by 40 feat In dimension, was removed from the south side of the driveway to access the south parcel, due to the site being within the Meadowdole Earth Subsidence Area a permit was required by the City of Edmonds for removal of the shed which was not obtained prior to removal. We performed a site reconnaissance on 1s September 1996 and:observed the slope area. The area is approximately 30 feet in width and slopes from the south edge of the drNoway down approximately 10 feet on a 31-1:1 V (Horizontal:vertical) to the generally level building pad. The surficial soils consist of a loose to medium dense silty sand with some gravel which was placed as fill soil excavated from the construction area. Apparently the contractor constructed the fill ramp for heavy equipment access to drill the piling and deliver building materials for the new construction. We did not observe remnants of the shed foundation at the surface, which possibly is buried under the ramp. The adjacent driveway slope to the east is covered with thiok aurfsoe brush, including blackberries and ivy, and elder and maple trees, and to the west downed trees for the site development are stockpiled. Further to the wait thick surficlai brush and native trees cover the slope. Groundwater seepage from the slope areas was not observed during our.reconnaiesance. 411c� Engineering a Environmontal Services FROM kIUIMAKItt TAD/FAY • PHONE NO. : +206 743 3109 . Sep_ 25 1995 03:25PM P2 Ann Kivimaki 11-10628.00 . 21 September 1966 Page 2 in review of the Edmonds (Earth Subsidence Criteria, the site is mapped as old landslide soils (Gols) with a 30 percent probability of slumps occurring during a 25-year period. In our opinion, the soil ramp from the gravel ddvewey to the building pad will not increase the potential for soil movement In this area, we recommend the following erosion control Measures be performed to the ramp area prior to the rainy season to prevent surficia) soil erosion. We recommend the ramp slope be track -walked with a bulldozer upslope. and downslope to provide -. ridges to interrupt runoff sheet flow. The final surface should be graded on a 3H:1 V slope with any ruts or depressions removed. The slope eras should be hydroseeded and maintained until vegetation becomes established. Depending on the season, it may be appropriate to protect the surface with visqueen or staked erosion control fabric until vegetation becomes established. If the ramp area is to be used for further construction access activities we recommend the slope be covered with a quarry spall rock. We recommend using 2- to 4-inch quarry 3pa113 for blanketing the ramp slope. After construction activities are completed, revagetation of the area should be performed as stated above. According to the property owner Me. Kivimaki, the ramp area at the south side of the 1 acre parcel Is to be revegetated and no development is planned in the near future. We trust this letter serves your current needs. If you have any questions please do not hesitate to call. Respectfully submitted, AGRA Earth & Environmental, Inc. urt R. Tho nps n Senior project Geol ist Kurt D. Merriman, P.S. Associate oIV Al. V CRT/KDMIiad 0A6RA �� Earth & Environmental 8g0 19y CITY OF EDMONDS 250 - 5TH AVE. N. • EDMONDS, WA 98020 • (206) 771-0220 • FAX (206) 771-0221 COMMUNITY SERVICES DEPARTMENT Public Works • Planning • Parks and Recreation • Engineering September 5, 1995 Torkjel Carlson 17630 18th Avenue West Lynnwood, WA 98037 RE: Demolition of abandon house without permit at 15604 75th Place West Dear Mr. Carlson: LAURA M. HALL MAYOR According to our records on June 9, 1995 Ursula Schluter submitted a Building Permit Application under your signature for a permit to demolish the abandoned house on property you own at 15604 75th Place West. .On June 15, 1995 a City letter was sent notifying Ms. Schluter, Linda Carlson (assumed trustee), and yourself that additional information was needed before the permit application could be approved to ensure that the requirements of the Critical Areas and the Meadowdale Earth Subsidence Area Ordinance(s) were met. After receipt of this letter, the permit application was withdrawn by Ms. Carlson on your behalf on June 27, 1995. It has come to our attention and verified by site inspection, that the abandoned house has since been demolished without first obtaining the required development permits including the building demolition permit. This is in violation of Chapters 19.00, 19.05, and 20.15B of the Edmonds Community Development Code and is subject to penalties as outlined therein. Since these violations have been verified by staff, within 15 days from the date of this letter, you must apply for the required permit to demolish the house. The application shall include a written report prepared by a licensed geotechnical engineer of the State of Washington. The report shall reference compliance with requirements of the Critical Areas Ordinance and Meadowdale Earth Subsidence Ordinance and make specific reference to protection of exposed slopes and impact of such work on a known landslide area. Failure to submit the required permit application by September 25, 1995 shall initiate the first stage of the Civil Penalties Ordinance, whereby issuance of an Order to Correct Violation will be posted on site. Please contact us if you have any questions at 771-0220. It is not our intent to cause you undue hardship however, as property owner you are ultimately responsible to resolve this violations and compliance -to the code is mandatory to ensure the fair and equal treatment of all citizens. Sincerely, Jeanine L. Graf, Bui din Ificial Ann Bullis, Code Enforcement Officer cc: U. Schluter Linda Carlson • Incorporated August 11, 1890 • Sister Cities International — Hekinan, Japan 890.19 June 15, 1995 CITY OF EDMONDS 250 - 5TH AVE. N. • EDMONDS. WA 98020 • (206) 771-0220 • FAX (206) 771-0221 COMMUNITY SERVICES DEPARTMENT Public Works • Planning . Parks and Recreation • Engineering Ursula Schluter 21701 80th Avenue West, #4 Edmonds, WA 98026 RE: Proposed demolition of dilapidated house at 15604 75th Place West Dear Ms. Schluter: LAURA M. HALL MAYOR We understand that you are working on behalf of Torkjel Carlson. On June 14, 1995 a site inspection was conducted at 15604 75th Place West to render a Critical Areas Determination. There is some confusion because the building permit application description of work states that a shed will be demolished, while the site inspection revealed an abandoned house. Assuming it is the house that will be demolished, it appears to be located within the buffer of a Steep Slope Hazard Area.as defined in the Critical Areas Ordinance. Since the house is located right on the edge of a steep slope, there is concern that the methodology and equipment used to demolish the house may create soil disturbance and possible erosion of the slope, thereby impacting the critical area. Before it is possible to determine if a conditional waiver of the required Critical Areas study may be granted, more information is needed. Please submit a site plan showing the location and square footage of the house, and explain in writing how you will be demolishing the house, what machinery you will be using, what time frame the work will be completed in, under the supervision of whom (i.e. licensed P.E.) and what protective measures you will be taking not to disturb the soil or slope. Also, granting of permission to demo the structure and obtain access for demolition and construction of your new residence, must be done in writing by Torkjel Carlson or his attorney -in -fact. Please submit a signed statement from Mr. Carlson or his attorney -in -fact with appropriate documentation, giving you such permission. Should you have any questions, please feel free to contact us at 771-0226. Sincerely, Ann Bullis Jeannine L. Graf Code Enforcement Officer Building Official cc: Torkjel Carlson, 17630 18th Avenue West, Lynnwood, WA 98037 Linda T. Carlson, 15604 75th Place West, Edmonds, WA 98026 • Incorporated August 11, 1890 • Sister Cities International — Hekinan, Japan 1 f 890.199i 0 STREETS FILE � CITY OF EDMOND 250 - 5TH AVE. N. • EDMONDS, WA 98020 • (206) 771-0220 • FAX (206) 771-0221 COMMUNITY SERVICES DEPARTMENT Public Works • Planning • Parks and Recreation • Engineering June 1, 1993 L. Carlson 15604 - 75th P1. W. Edmonds, WA 98026 LAURA M. HALL MAYOR This letter is to inform you that you are served by a city maintained grinder pump system. This system pumps.your sanitary waste to city gravity sewer lines as your house was too low to obtain gravity flow when city sewer mains were installed. I hope to inform you of the basics of how these pumps function, who to call should you experience alarms, and what precautions should be -taken to prevent damage to your home. 1. The grinder pump -was originally installed by the homeowner, but the hardware was purchased by the city of Edmonds' Lid Bond that paid for the sewer project in your area in 1985. These pumps are float activated to cycle the one pump to take your sewage up to where gravity flow can be obtained. 2. The following precautions must be adhered to prevent damage to your home: A. Do not dump any nonbiodegradable products down into the pump tank. VIA your drains in your house. B. Minimize the amount of grease disposed down your drain. This may cause problems with the float operations. C. Do not empty pools into the tanks without a restrictor approved by the city of Edmonds. D. Do not attempt to access tank or electrical cabinets. Should you have a pump failure from any of the above mentioned items, the homeowner will be held responsible for damage. 3. The city of Edmonds Sewer Section will maintain the pumps every three (3) months to ensure the proper operations.' We will also clean, operate and check all components to ensure$ proper working status. A separate log is kept to your pump that will reflect any maintenance done. We can track reliability and the need for upgrade or repairs when a chain.of failures start to occur. Crews will require the use of your water so the -tank can be washed down and we will always try to notify you of their presence when they arrive on the site. 4. Should you experience any problems with the pump, there are two alarms that will indicate failure. One alarm is located within your home and has a black push button to reset to silence. There is also a visual alarm located on the electrical box outside your home. When this occurs, please call us at 771-0235 immediately to investigate any problems. Our office hours are 8:00 AM -.5:00 PM Monday Through Friday. Should an alarm occur after hours, weekends, or holiday, contact 911. There is a 24-hour call person on duty to be dispatched. We do carry parts for all of these systems and should be able to correct most problems within a reasonable amount of time. If you have any questions or concerns, please contact Everett.Akau or myself at 771-0235, extension 349. Sincerely, QW "�) Ron Holland Water/Sewer Supervisor cc: Everett Akau RH/lk GRIND/LT/TXTSEWER ' EDMONDS CITY COUNCIL AGENDA MEMO Item number: Originator: Robert J. Alberts For Action: x For Information: SUBJECT: AUTHORIZATION FOR MAYOR TO SIGN PERMIT TO SUPPLEMENT EXISTING PERMIT WITH BURLINGTON NORTHERN RAILROAD AGENDA TIME: Consent AGENDA DATE: February 2, 1988 EXHIBITS ATTACHED: Transmittal letters from: Burlington Northern RR Harrison Jewel Reid, Middleton & Assoc. Vicinity Map Permit Supplement Clearances: Dept./Indiv./Initials ------------------ ------------------ ADMIN SVCS/FINANCE CITY ATTORNEY CITY CLERK COMMUNITY SERVICES ENGINEERING PARKS & RECREATION PLANNING PUBLIC WORKS FIRE PERSONNEL POLICE COMMITTEE MAYOR COMMENTS: EXPENDITURE AMOUNT APPROPRIATION REQUIRED: $0 BUDGETED: $0 REQUIRED: $0 HISTORY AND SUMMARY STATEMENT: Harrison Jewel and Jean Riggle are property/home owners in the Meadowdale area. They are preparing to build/remodel. They approached the City with their proposed drainage plans and were instructed to obtain approval for their proposal from Burlington Northern Railroad. Burlington Northern staff have indicated their approval of the Jewel/Riggle proposal. Burlington Northern have forwarded a supplement (for Jewel/Riggle) to the existing permit for the City (obtained prior to construction of LID 210). RECOMMENDED ACTION: Authorize Mayor Naughten to sign the supplement to the permit. COUNCIL ACTION: BNRRPER/TXTAGNDA kzu( ..u�,d�.;�;Y ,f �..:,�;�'� a.�h!_��.k>� ;4!4.�R-.-i4...P..�-��. '�rJi�uc•..�i�ifht.. BURUNGTON NORTHERN RAILROAD 2000 First Interstate Center 999 Third Avenue Seattle, WA 98104-1105 .206-467-3289 Reid, Middleton & Associates, Inc. October 29, 1987.. 121 5th Avenue North - Suite 200 Edmonds, WA 98020 Attention: Allan R. Morgan Associate Engineer Gentlemen' i.. RE: Supplement to Permit No. 245260 for additional storm pipeline at'. MEADOWDALE, WA Enclosed, in duplicate, is the above=mentioned' agreement. , BOTH copies h p should be signed in the presence of witnesses and returned. for signature on behalf of Burlington Northern"Railroad Company' One copy will be returned for your records.' At that time, you may contact the roadmaster and begin occupancy of Burlington Northern property. There is no charge for this supplement as in this way the Railroad may update their inventory of facilities on Railroad property and/or Right of Way. Kindly refer to file number shown below when phoning and/or correspond- ing about this permit until finalized. Sincerely, Bob Luckey Permit Clerk/PACIFIC DIVISION Enc. File: 5133 Edmonds i January 20, 1988 City of Edmonds Engineering Department Dear Mr. Hauth: Enclosed is my permit from Burlington Northern —Railroad authorizing attachment to their drain pipe which runs under their right"ofiiway. The city required me to provide plans showing where'+the water off my roof and• lot were to be discharged. I hired Reid, Middleton &'Associates to draw the plans and get the necessary permit from the railroad.;' It would be appreciated if you would have the engineering department sign the supplement. I will then forward it to the railroad and another requirement of the city will be satisfied. i I• Thank you for your'help regarding this matter. Sincerely yours, Harrison Jewell 5535 Seaview Ave NW Seattle, WA 98107 789-5010 or 789-1382 e Reid, Middleton & Associates, Inc. :Engineers Surveyors Pionners November.:.9, 1987 File No. 02-86-130-001 Mr. Harrison Jewell 5535 Seaview Ave. N.W. Seattle, Washington 98107 Subject: Burlington Northern Supplement to Permit No. 245260 for New Storm Sewer Additions Dear Mr. Jewell: Pursuant to our telephone conversation this morning, enclosed please find the two copies of the permit and a copy of Mr. Luckey's transmittal with instructions for you to follow. Please note that there is a signature line for Jean Riggle on this supplement. If she doesn't wish to sign the document please contact our office so that we can contact Burlington Northern regarding possible problems. If you have any question please contact our office. Sincerely, REID, MIDDLETON & ASSOCIATES, INC. Allan R. org Associate Eng' eer i Encl. AR4: bb: ALLAN: JEWELL BN I 121 5th Avenue North, Suite 200, Edmonds, \Voshington 98020 (206) 775-3434 ' VICINITY MAP SUPPLEMENT TO PERMIT 245260 BY MUTUAL AGREEMENT, the description in that certain permit numbered 245260, dated October 1, 1983, issued to CITY OF EDMONDS, whose post office address is Civic Center, Edmonds, WA 98020 by the BURLINGTON NORTHERN RAILROAD COMPANY (formerly BURLINGTON NORTHERN INC.) a Delaware corporation, hereinafter called "Railroad", authorizing an 18-inch stormwater pipeline, hereinafter referred to as the "facility,", located at or near MEADOWDALE Station, in the County of Snohomish, State of Washington is hereby amended to read as follows: For Mr. Harrison Jewell, P.O. Box 17481, Seattle, WA 98107 & Mrs. Jean Riggle, 15714 - 75th Place West., Edmonds, WA 98020 the placement of a 6" storm pipeline, as shown colored green on the plat hereto attached, marked Exhibit "A" dated October 29, 1987, an�this reference thereto made a part hereof, which will attach to the "facility" as described in that certain permit numbered 245260, dated October 1, 1987, and located at Survey Station 1242+03 - Milepost 21.56 at or near MEADOWDALE Station, in the County of Snohomish, State of Washington, with said pipe to be anchored into the hillside with a six foot fence posts at 20' intervals, or less, to adequately support the pipe, installation to be done by hand with the slope to be restored to its present, or better, conditions under the supervision and inspection of the Railroad's Roadmaster. Except as hereby amended, all other terms and conditions of said permit shall remain in full force and effect. This agreement is effective as of the 16th day of NOVEMBER, 1987. IN WITNESS WHEREOF, the parties hereto have executed these presents the day and year first above written. BURLINGTON NORTHERN RAILROAD COMPANY Witnesses to Execution by APPROVED AS TO FORM: City Attorhby By Division Engineer CITY OF EDMONDS By Title Witnesses to Execution by HARRISON JEWELL Witnesses to Execution by JEAN RIGGLE i\ �♦ '\, t pp } • ,ire ' � •C: p i s . t � tir1 ��ti .. \ - A \ ,. �/ - � rti'+`� Fit `t• rM.f .�a t `'i: I. s�i� ,.e{�!! i}irr':. P r ' L,w a �`atiV :'i a. • '.\ �\� _ I � r . � '. +• N+yC t t � 'a ( :. . • � � t ++ 1 i\ �rn�;ls ♦ � =F Ya• ��, . may• t'..' � \ 4' t r _ • - f.. � N vLl tl 044. '♦ `�4 .4y r ; 'r•!F gyp'° i •+�,G•1 r �'. s i• a r♦ ♦, , e4 G v `f r 1 ' t r ♦+ r t I .: 4 " .+ +));�\) r 41 py r r; �{G i �• 11 .y'z ` i ` `. t\°J j(''pp ♦♦ • �•r ;L I.: iA' •' it�'1,J'% I IS f a t yr .'L ~�, 1 ��O .y1, \ , ♦ • F` w` c Y: I ! `{' i jr1' •;y,j: ►`•(j p?�I r` 1, 1 1 r �R'tryr \t <•zii v ' ( r' ^r rsti ,. .r 7 ♦. 1 ,.. ' 't 1 j '. >jt 1 • i � • • -,l,�... : , ;'•r �1.Z . ' 1 Q � � •�•f Itd t / ' lY r o \•r ' C. : � q.. r" \ Z i U•r9+ t l�.r 1• i�:� �� { Yip, ,r r. 1 \ .:s r �(`1G7m (9t /' `t}Fj �• •r •r t 4. F - rf p•a0 � Q X � %.'� a t.L♦�ic ,9 1: - " Sr � a_. f I �;. ;.♦ Zw - :t / i:r7` Y f. •,f. x r ,.l 'f { 0...i V t .LI i S , t 4 o Z p / y. it 1 SUBSURFACE EXPLORATION, GEOLOGIC HAZARDS AND PRELIMINARY GEOTECHMCAL ENGINEERING REPORT ALDRIDGE SHORT PLAT EDMONDS, WASHINGTON PREPARED FOR Ms. Theresa Aldridge PROJECT NO. G97224A OCTO C1j9- 7ED flV FEB 1 1 2G63 ' CORPORATE OFFICE PERMIT COUNTER 911 Fifth Avenue, suite 100 ASSOCIATED Kirkland, Washington 98033 (425) 827-7701 EARTH FAX (425) 827-5424 SCIENCES, INC BAINBRIDGE ISLAND OFFICE 179 Madrone Lane North Bainbridge Island, WA 98110 (206) 780-9370 y_ Ej LE FAX (206) 780-9438 a �. I ' i I SUBSURFACE EXPLORATION, GEOLOGIC HAZARDS AND PRELIMINARY GEOTECHNICAL ENGINEERING REPORT ALDRIDGE SHORT PLAT 15604 75 `H PLACE WEST EDMONDS, WASHINGTON October 24, 1997 Project No. G97224A I. PROJECT AND SITE CONDITIONS 1.0 INTRODUCTION ' This report resents the results of our subsurface exploration, geologic hazards and P P P g g preliminary geotechnical engineering study for the proposed residential 2-lot plat, located at 15604 75`' Place West, Edmonds, Washington. Our study was performed with the understanding that the 1'/a acre property is proposed to be subdivided into 2 residential lots. The locations of existing and proposed structures and the approximate location of the ' subsurface explorations completed for this study are presented on the Site and Exploration Plan, Figure 1. In the event that any changes in the nature, design, or location of the structures are planned, the conclusions and recommendations contained in this report should be reviewed and modified, or verified, as necessary. 1 1.1 Purpose and Scone The purpose of this study was to provide subsurface soil and shallow ground water data to be utilized in the preliminary design and development of the subject residential project. This report is intended to comply with the City of Edmonds Geotechnical Report Guidelines for sites within the Meadowdale area (ECDC 19.05.03013). Our field study included the excavation of four exploration pits, three exploration borings, the installation of two slope inclinometers, and performing geologic studies to assess the type, thickness, distribution and physical properties of the subsurface sediments. Geotechnical engineering studies were also conducted to determine seismic and landslide hazard considerations, the type of suitable foundation, allowable foundation soil bearing capacities, anticipated foundation settlements, floor support considerations, utility connection considerations, lateral wall pressures, and drainage considerations. We also reviewed a geotechnical report prepared by Terra Associates, Inc: dated July 28, 1990 conducted for the property to the north of the subject property. This report summarizes our recent field work and offers development recommendations based on our present understanding of the project. Also, this report is I preliminary and subject to modification due to ongoing slope monitoring and potential changes in development plans. 1.2 Authorization Written authorization to proceed with this study was granted by Ms. Theresa Aldridge. Our study was accomplished in general accordance with our proposal dated August 18, 1997. This report has been prepared for the exclusive use of Theresa Aldridge, and her agents, for specific application to this project. Within the limitations of scope, schedule and budget, our services have been performed in accordance with generally accepted geotechnical engineering and engineering geology practices in effect in this area at the time our report was prepared. No other warranty, expressed or implied is made. Our observations, findings, and conclusions are a means to identify or reduce inherent risks to the owner. 111 2.0 SITE AND PROJECT DESCRIPTION The subject property is located at 15604 75" Place West. The approximately 260 foot north - south by 195 foot east -west rectangular -shaped property was bordered on the west by the Burlington Northern Railroad, on the east by 75`'' Place West, and on the north and south by single family homes. Puget Sound was located just west of the Burlington Northern Railroad. The railroad tracks lie approximately 40 feet west of the western property line. The subject property sloped down from 75`' Place West to the railroad tracks. Three existing structures were located on a gently sloping bench with steep slopes located on the west and to the east. To the west, a steep, approximately 55 percent slope, 40 feet tall, sloped down towards the railroad tracks. Many of the taller trees on this steep western slope were tilted downslope. To the east, a steep, 65 to 75 percent slope rose up towards 75`, Place West. The slope to the east varied from a few feet high at the south end to 32 feet at the north. Existing structures on the property consisted of a dilapidated house, utility building, and storage shed. The house was a wood -frame, one-story structure with daylight basement and was located on the north side of the property. The utility building was a wood -frame, two- story structure with a crawlspace and was located on the south side of the property. The storage shed was located approximately 45 feet west of the utility building. The existing home revealed evidence of previous subsurface soil movement. The basement retaining and foundation walls were cracked and out of plumb. In addition, window frames were askew and the home was generally tilted to the west approximately 6 inches. Preliminary plans are to demolish the existing structures and construct two new homes. The new homes are to be located near the existing buildings. New construction will consist of two- story wood -frame homes with attached garages. Daylight basements and/or retaining walls are possible. 1 Vegetation, within and surrounding the proposed building sites consisted mostly of blackberry vines with a few deciduous trees. Utilities to the existing house consisted of sewer and _ overhead power. The electrical power line to the house was observed to be under tension most likely due to downslope movement of the house. A sewer pump vault was located near the southeast corner of the house. The location of a water supply was not determined. However, 1 according to a nearby neighbor, Norm Nelson, an abandoned water well was located near, or possibly beneath, the existing house. 2.1 Background The Meadowdale area, including the subject property, has been identified as an earth subsidence/landslide area. The main Meadowdale landslide likely occurred several thousand years ago. According to Terra Associates, Inc.'s report and conversations with a nearby homeowner, parts of the original slide have more recently moved during the winters of 1946- 47, 1955-56, and during the 1960s and 1970s. According to Norm Nelson, slope movement in the winter of 1955-56 caused damage to the existing house. On the subject property there was evidence of subsurface movement that may have occurred as recently as this last winter.. This evidence consisted of tension cracks and scarps which were not heavily eroded or overgrown with vegetation. Several previous, regional -scale geotechnical studies have been completed by others to evaluate the landslide hazard potential within the Meadowdale area. In 1979, Roger Lowe Associates, Inc. estimated landslide failure probabilities on a map of the Meadowdale area. At the time of Lowe's report, Lowe estimated that the subject property had a 90 percent chance of landslide movement during a 25-year period. In 1980 through 1985, sanitary sewer, storm sewer, and ground water interceptor drains were installed within landslide areas based on recommendations from Lowe's report. In 1985, GeoEngineers, Inc. revised Lowe's landslide probabilities based on the installation of ground water control improvements. For the subject property, the probability of a landslide occurring in a 25-year period was reduced by GeoEngineers from 90 percent to 30 percent. 3.0 SUBSURFACE EXPLORATION Our field study included excavating a series of exploration pits, drilling exploration borings and the installation of two slope inclinometers to gain subsurface information about the site. The exploration pits were excavated on August 18, 1997 and the exploration borings with slope inclinometers were completed on September 9 and 10, 1997. Our field work was conducted during an extended period of dry weather. The various types of sediments, as well as the depths where characteristics of the sediments changed, are indicated on the exploration logs presented in the Appendix. The depths indicated on the logs where conditions changed may represent gradational variations between sediment types in the field. Our explorations were approximately located in the field by measuring from known site features shown on a site plan with topographic information prepared by Cramer Northwest, Inc. dated September 4, 1997. 1 The preliminary conclusions and recommendations presented in this report are based on the 4 exploration pits and 3 exploration borings completed for this study. The number, location, and depth of the explorations/borings were completed within site and budgetary constraints. Because of the nature of exploratory work below ground, extrapolation of subsurface conditions between and beyond field explorations is necessary. It should be noted that 1 3 differing subsurface conditions may sometimes be present due to the random nature of deposition and the alteration of topography by past grading, filling, and landsliding. The nature and extent of any variations between the field explorations may not become fully evident until construction. If variations are observed at that time, as new information becomes available, it may be necessary to re-evaluate specific recommendations in this report and make appropriate changes. This report is preliminary and subject to modification based on future monitoring of the slope inclinometers installed on the property. 3.1 Exploration Pits Exploration pits were excavated with a track -mounted Case 9010B 30,000-pound excavator to a depth from 15 to 18 feet below present surface grade. The pits permitted direct, visual 1 observation of subsurface conditions. Materials encountered in the exploration pits were studied and classified in the field by a geotechnical engineer from our firm. All exploration ' pits were backfilled immediately after examination and logging. Selected samples were then transported to our laboratory for further visual classification and testing, as necessary. 1 3.2 Exploration Borings The exploration borings were completed by advancing a 4'/4 inch inside -diameter, hollow - stem auger using a track -mounted drill rig. During the drilling process, samples were obtained at generally 2.5 or 5.0-foot depth intervals. The borings were continuously observed and logged by a geotechnical engineer from our firm. The exploration logs presented in the Appendix are based on the field logs, drilling action, and inspection of the samples secured. 1 Disturbed but representative samples were obtained by using the Standard Penetration Test procedure in accordance with ASTM:D-1586. This test and sampling method consists of driving a standard 2 inch outside -diameter, split barrel sampler a distance of 18 inches into the soil with a 140 pound hammer free -falling a distance of 30 inches. The number of blows for each 6 inch interval is recorded and the number of blows required to drive the sampler the final 12 inches is known as the Standard Penetration Resistance ("N") or blow count. If a total of 50 are recorded within one 6-inch interval, the blow count is recorded as 50 blows for the number of inches of penetration. The resistance, or N-value, provides a measure of the I relative density of granular soils or the relative consistency of cohesive soils; these values are plotted on the attached boring logs. 1 3.3 Slope Inclinometers Two slope inclinometers were installed on the property to monitor potential slope movement. Slope inclinometer 1 (SI-1) was located within EB-1 and SI-2 was located within EB-3. The slope inclinometer casing consists of 2 inch diameter PVC pipe that has 4 vertical grooves. An instrument is periodically lowered down the casing via the groove tracks to measure the casing profile. These measurements are taken to determine the magnitude of movement over time. 1 4.0 SUBSURFACE CONDITIONS Subsurface conditions on the parcel were inferred from the field explorations accomplished for 1 this study, visual reconnaissance of the site and review of applicable geologic literature. As shown on the exploration logs, the exploration holes generally encountered fill and colluvium materials overlying natural silt/clay and sand deposits. The following section presents more ' detailed subsurface information organized from the upper (youngest) to the lower (oldest) sediment types. 4.1 Stratigraphy ' Fill . Fill soils -(those not naturally placed) were encountered in all four exploration pits and in all three exploration borings. The fill was approximately 4 feet deep in EP-2, EB-2, and EB-3. In EP-4 and EB-1 the fill was estimated to be approximately 8 to 10 feet deep, respectively. Disturbed/fill soils were observed to a depth of 3 feet in EP-1 and EP-3. As noted on the ' exploration logs, the fill varied in material properties. Within EP-2, the fill generally consisted of loose, moist, brown, sand and gravel. In EP-4 the fill consisted of loose, dry, dark brown, fine sand with gravel, roots, and chunks of asphalt. In EB-1 and EB-2 fill soils consisted of loose, damp, reddish -brown, sand with varying amounts of gravel. The fill soils appeared to vary in both quality and depth across the site. Since the quality, thickness and compaction of the fill materials are variable, the fill is unsuitable for foundation support. Possession Drift Natural soils beneath the fill materials consisted, for the most part, of stiff, moist, bluish -gray, clay or silt and occasional lenses of silty fine sand. These sediments were encountered in our exploration pits from depths ranging from 3 feet (EP-1) to 12 feet (EP-3) beneath present surface grade and extended below the termination depth. In our exploration borings these sediments were first encountered from approximately 4 feet (EB-2 and EB-3) to 11 feet (EB-1) ' below present surface grade. These sediments extended to 32'/z feet, 27 feet, and 17 feet below surface grade in EB-1, EB-2, and EB-3, respectively. ' The stiff bluish -clay sediments have been interpreted as Possession Drift sediments. These Possession Drift sediments were deposited in a glacial lake environment and subsequently overridden by multiple glaciations. Double Bluff Drift Beneath the fine-grained Possession Drift sediments, our three exploration borings terminated in very dense, moist, light brown, fine sand. The termination depth of our borings was at 36'h feet below present surface grade. These fine sand sediments have been interpreted as Double Bluff Drift glacial deposits. 1 1 1 1 i 1 1 1 1 1 1 1 1 1 i 1 1 4.2 Hydrology Ground water was not encountered in any of our subsurface explorations. During wetter times of the year we expect some ground water seepage from perched zones on top of the Possession clay sediments and within sand lenses. In the Puget Sound Basin, the Possession Drift sediments are very fine-grained and in a compact condition which has resulted in a near impermeable barrier to the vertical movement of ground water. Minor horizontal movement. of ground water can be expected within thin sand lenses. No seepages were observed daylighting at the toe of the slopes located on the east and west sides of the proposed home locations at the time of our explorations. 0 I I October 24, 1997 Project No. G97224A IIL GEOLOGIC HAZARDS AND MITIGATIONS The following discussion of geologic hazards is based on the geologic, slope and ' ground/surface water conditions as observed and discussed herein. The discussion will be limited to seismic, landslides, and erosion. 5.0 SEISMIC HAZARDS AND RECOMMENDED MITIGATION Earthquakes occur in the Puget Lowland with great regularity. The vast majority of these events are small and are usually not felt by people. However, large earthquakes do occur as evidenced by the 1949, 7.2 magnitude event and the 1965, 6.5 magnitude event. The 1949 ( earthquake is the largest in this area during recorded history. More recently, the Puget Lowland experienced a moderate 5.4 magnitude event in the spring of 1996 and a 4.9 magnitude event in the spring of 1997. Evaluations of earthquake return rates indicate that an earthquake of the magnitude between 5.5 and 6.0 likely will occur within the next 8 to 12 years. The subject property is located near several identified significant fault. zones. The north- northwest trending South Whidbey Island/Lake Alice fault has been mapped through the 1 Meadowdale area. Recently, two north -south trending faults have been tentatively mapped beneath the waters of Puget Sound and within 10 miles southwest of the subject site. LThe Whidbey Island fault zone is interpreted to represent a significant boundary between two major crustal blocks. The fault originated as a right lateral strike -slip fault but vertical offset ' has also been identified. No recurrence interval has been conclusively determined for movement along the Whidbey Island fault, but is estimated to be thousands of years (Pratt, 1995). ' Published reports of the north -south trending faults beneath Puget Sound have not been completed at the time of this report. However, it is preliminarily estimated that the recurrence 1 interval for the faults is thousands of years. Generally, there are 4 types of potential geologic hazards associated with large seismic events: 1) surficial ground rupture; 2) seismically induced landslides; 3) liquefaction; and 4) ground motion. The potential for each of these hazards to adversely impact the proposed project is discussed below. 1 5.1 Surficial Ground Rupture tGenerally, the largest earthquakes, which have occurred in the Puget Sound/Seattle area, are sub -crustal events with epicenters ranging from 50 to 70 kilometers in depth. Therefore, it is ' 7 11 k I 1 1 our opinion, based on existing geologic data, that the risk of surface rupture impacting the proposed project is low and no specific mitigations are recommended. 5.2 Seismically Induced Landslides The steep slope located on the east side of the proposed home locations likely consists of shallow surficial fill soils used for the road grade, overlying natural stiff silt/clay sediments. As previously mentioned, no seepages were observed at the toe of the slope. Various areas of the slope were evaluated using a soils probe. Probing with a standard soil probe indicated that stiff sediments were present at shallow depths (approximately one foot) on the slope. Based on probing, geologic literature, and our reconnaissance of the area, it is our opinion that the core of the slope is comprised of consolidated, natural sediments. Due to the soil density and lack of adverse ground water conditions, the potential for a seismically induced landslide of the core of this slope is interpreted to be low. Mitigation for this slope will include leaving mature, natural vegetation intact, preventing runoff from discharging onto the slope, and possible enhancement of native ground cover plants to reduce the potential for surface erosion. The steep slope on the west side of the proposed home locations consisted of Possession Drift sediments (clay) as observed on the slope surface. Near the top of the slope at the northwest corner of the property was a 2 to 3 foot tall vertical landslide scarp. The ground below the 1 scarp likely shifted last winter based on the lack of erosion and overgrowth of the scarp face. Another shallow scarp was identified near the existing shed. This scarp appeared older, was overgrown and the vertical offset of the ground surface was a few inches. The trunks of 1 several trees on the slope were observed to be tilted slightly downslope indicating ongoing slope movement. No seepages were observed at the toe of the slope. ' Due to the history and recent evidence of subsurface soil movement on .the property, the steep slope to the west of the proposed home locations is interpreted to have a om derate to 'gh potential for a seismically i`nduced-landslides. Landslide mitigations are presented in Section ' 6.0, Landslide Hazards and Mitigation. ' 5.3 Liquefaction Liquefaction is a condition where loose, saturated, fine-grained soils lose shear strength when ' subjected to high intensity, cyclic loads of very short duration, such as occur during earthquakes. The resulting reduction in strength can cause differential foundation settlements and slope failures. Loose, saturated, fine-grained sands, which lack cohesion and cannot 1 dissipate the buildup of pore water pressure, are most susceptible to liquefaction. Based on our review of the samples obtained from our explorations, it is our opinion that the encountered stratigraphy has a very fine-grain size, cohesive (clay) sediments that have been glacially consolidated. The sediment type is not prone to liquefaction. Therefore, there is a low potential for soil liquefaction and no mitigations are recommended. �I 5.4 Ground Motion 1 f! 1 1 Based on the stratigraphy and visual reconnaissance of the site, it is our opinion that any earthquake damage to the proposed structures founded on a suitable bearing strata, and following the recommended setback recommendations, would be caused by the intensity and acceleration associated with the event and not any of the above discussed impacts. Structural design of the building should follow UBC standards for Seismic Zone 3. 6.0 LANDSLIDE HAZARDS AND MITIGATION The potential landslide risk can be divided into two depth categories; shallow and deep. The potential shallow (approximately 8 feet thick) landslide risk includes the fill soils on top of the Possession Drift (clay) sediments. Based on discussions with Norm Nelson and on our subsurface investigation, the existing house was likely damaged from a shallow landslide. In addition, the presence of landslide scarps, which appear to be recent, indicate that there has been recent shallow landslide soil movement. The potential deep, landslide risk has been identified at the Possession (clay) and Double Bluff (fine sand) contact. This deeper slide surface was identified at depths of approximately 31 feet, 26 feet, and 16 feet in EB-1, EB-2, and EB-3, respectively. Currently, it is not known whether the deep-seated slide is active, has been active in the recent past, or is ancient. Slope inclinometers were installed to assist in the evaluation of whether the deep-seated slide plane is currently active. On a preliminary basis, we concur with the assessment by GeoEngineers that the subject property has a 30 percent probability of ground failure within a 25-year period. The risk for shallow landslides can be reduced by several methods. Currently the roof ' downspouts from existing structures discharge onto soft/loose fill soils. In addition, the soft/loose soils surrounding the house have open tension cracks, which readily permit the ' infiltration of surface runoff, exacerbating the landslide potential. The risk of shallow landslides can be partially mitigated through the control of storm water runoff as described in Section 15.0, Drainage Considerations. Portions of the property can be graded to further reduce the potential for shallow slope movement. The buffer area between the top of the western slope and the proposed homes can ' be terraced. Terracing the moderate slope by the removal of 3 to 6 feet of soil would reduce the potential of shallow soil movement by reducing the weight of excess fill soil at the top of the slope. At no time should fill be pushed over or placed near the top of slopes. 1 Buildings should be set back from the toe of the eastern slope b 20 feet. Preliminary to of g P Y Y P ' slope setbacks of 35 feet and 25 feet are recommended for the western slope and the southern slope, respectively. These slope setbacks are subject to modification based on periodic monitoring of the property through the winter. Associated Earth Sciences, Inc. (AESI) should review grading plans to address slope stability concerns. Through the proper management of storm water runoff and proper grading of the property, the 1 potential risk of shallow subsurface movement can be reduced but it must be understood that some risk will always remain. This risk can be quantified by slope stability modeling during the design optimization phase of the project. ' 9 1 iSignificant grading of the property should be limited to dryer times of the year (May 1 to October 1). ' Since our explorations were completed during the dry summer months, an accurate assessment of potential ground water conditions was not possible. If our continued monitoring reveals slope movement, seepage/spring activity, or other drainage concerns, it is recommended that additional subsurface work (exploration pits or borings) be conducted during wetter times of the year to assess ground water conditions and their potential impacts to slope stability. 7.0 EROSION HAZARDS AND MITIGATION When disturbed, the encountered surficial sediments, as well as sediments at depth, possess a ' moderate potential for erosion, even on gentle to moderate sloping areas, when subjected to concentrated flows. Therefore, storm water runoff should be collected, routed and discharged through a suitable, City approved storm water system. Uncontrolled discharge from impermeable surfaces should not be allowed to flow across or infiltrate into the site sediments. It is our understanding that the existing structures may be demolished during the fall or winter of 1997 with new construction to occur at a later date. Erosion control measures for the demolition phase of work should consist of the following: 1. Placement of 2 inch or larger crushed rock for construction equipment access road improvements. 2. Once existing structures have been demolished, all exposed ground surfaces should be hydroseeded and mulched with a suitable seed/mulch erosion control mixture. 3. All work should be confined to the immediate vicinity of the structures and 1 access road. 1 4. Additional measures should be employed as necessary to prevent off -site sediment transport. Once new development activities are begun, to mitigate erosion and off -site sediment transport, we.recommend the following measures: I 1. A silt fence should be constructed at the lower portion of the property to intercept any sediment eroded during the construction phases of the project. 1 2. The outlets from detention/retention facilities on the property should be designed to prevent direct flow over unprotected slopes. This can be accomplished by tightlining the outlets down to the toe of the western slope. 1 All disturbed areas should be re -vegetated or landscaped as soon as possible. 3. A g p ' 10 1 1 1 1 1 1 t 1 1 1 1 1 1 4. If construction occurs after October 1 and before April 1, exposed ground should be maintained with a mulch cover. 5. Surface runoff must not be directed onto or above the steeply sloping areas. All devices used to collect surface discharge should be directed into a tightlined system, which discharges away from slope areas. Uncontrolled discharge on slope areas will promote erosion and slope instability. 6. Temporary erosion and sedimentation facilities must be maintained and improved as necessary to control runoff and off -site sediment transport. 11 1 11 1 i] LI LI 1 October 24, 1997 Project No. G97224A III. PRELIMINARY DESIGN RECOMMENDATIONS 8.0 INTRODUCTION Our exploration indicates that, from a geotechnical standpoint, the parcel is suitable for the proposed development with the understanding and acceptance that some risk of earth movement will always be present. The foundation -bearing stratum is relatively deep, approximately 9 feet below present surface grade. Due to the history of landslide movement and a thick sequence of landslide, fill, or disturbed soils, we recommend the installation of a deep foundation system (piles) for the new structures. A pile foundation is also recommended for support of garages and slab -on -grade floors. Pavements for driveways can be supported on compacted existing fill or structural fill that is placed atop compacted existing fill. Recommendations for preparation of driveway subgrades are discussed in the Site Preparation section of this report. Our foundation recommendations are based on the preliminarily interpretation that the deep- seated landslide potential is inactive. Therefore, the recommendations in this report are preliminary and subject to modification based on results of future monitoring of the site. A pile foundation will not prevent damage from a deep-seated landslide. The conclusions and recommendations presented in this report are offered as a means to identify and reduce risks associated with steep slopes, erosion and seismic hazards. Elimination of risks from geologic hazards, as identified on this site, are not possible. It should be understood that our recommendations are not meant to fully mitigate against future earth movement, but will provide vertical foundation support only, without increasing the risks of slope movement. Development of the site using any of the recommendations presented in this report may only proceed if the owner accepts full responsibility for any damage in the event of slope movement. 9.0 SITE PREPARATION To mitigate the potential shallow landslide hazard we recommend that within critical landscape areas, the top 4 to 6 feet of loose fill soils should be removed. Critical landscape areas are those areas adjacent to steep slopes, which may have an increased potential for slope failure. These critical landscape areas are within 30 feet of the top of the westerly slope. The landscape areas can be terraced in order to remove loose fill soils (overburden). The removal of loose soils is intended to reduce the risk of shallow landslide potential. Slope movement in these critical landscape areas may not directly impact the proposed residences, but would impact the buffer/setback zone between the houses and slope. Grading plans for these areas should be reviewed and approved by our office prior to construction. 12 Site preparation of planned building and driveway areas should include removal of all trees, brush, debris and any other deleterious material. Additionally, for driveway areas the upper organic topsoil should be removed and the remaining roots grubbed. Areas where loose ' surficial soils exist due to grubbing operations should be considered as fill to the depth of disturbance and treated as subsequently recommended for structural fill placement. Any buried utilities should be removed or relocated if they are under building areas. The resulting depressions should be backfilled with structural fill as discussed under the Structural Fill section. The soils at the site contain a high percentage of fine-grained material that makes them moisture -sensitive and subject to softening and disturbance when wet. We therefore recommend that earthwork operations should be performed during dry weather periods. ' 10.0 STRUCTURAL FILL There is a possibility that structural fill will be necessary to fill voids created by the removal of ' existing utilities or to establish desired grades for driveways. Under no circumstances should fill be placed on or near the steep western slope. All references to structural fill in this report ' refer to subgrade preparation, fill type, placement and compaction of materials as discussed in this section. If a percentage of compaction is specified under another section of this report, the value given in that section should be used. After the exposed ground is recompacted and approved, structural fill should be placed to attain desired grades. Structural fill is defined as non -organic soil, acceptable to the geotechnical engineer, placed in maximum 8 inch loose lifts, with each lift being compacted to at least 95 percent of the modified Proctor maximum density (ASTM:D-1557). The top of the compacted fill should extend horizontally outward a minimum distance of 3 feet beyond I pavement edges or building foundations before sloping down at an angle of 2H:1 V (Horizontal: Vertical). The contractor should note that any proposed fill soils must be evaluated, approved and laboratory tested prior to their use in fills. This would require that we have a sample of the material 48 hours in advance to perform a Proctor test and determine its field compaction standard. Soils in which the amount of fine-grained material (smaller than No. 200 sieve) is greater than approximately 5 percent (measured on the minus No. 4 sieve size) should be ' considered moisture -sensitive. Use of moisture -sensitive soil in structural fills should be limited to favorable dry weather and dry subgrade conditions. ' The near -surface, on -site soils generally contained significant amounts of silt and are considered moisture -sensitive. At the time of our field work, the on -site, near -surface soils, were too wet to compact as structural fill. Construction equipment traversing the site when the soils are wet can cause considerable disturbance. If fill is placed during wet weather, or if proper compaction cannot be obtained, a select fill material consisting of a clean, free -draining gravel and/or sand should be used. 1 13 1 1 fl I P I I r 7 I Free -draining fill consists of non -organic soil with the amount of fine-grained material limited to 5 percent by weight when measured on the minus No. 4 sieve fraction. A representative from our firm should inspect the stripped subgrade and be present during placement of structural fill to observe the work and perform a representative number of in - place density tests. In this way, the adequacy of the earthwork may be evaluated as filling progresses and any problem areas may be corrected at that time. It is important to understand that taking random compaction tests on a part-time basis will not assure uniformity or acceptable performance of a fill. 11.0 FOUNDATION RECOMMENDATIONS As discussed in the first half of this report, the proposed building areas are underlain by fill and soft/loose soils, which are up to 9 feet thick. The depth of these sediments and their soft/loose condition would likely result in excessive total and differential settlement of a conventional, shallow foundation constructed on or within this material. Extended spread footings founded on stiff clay sediments were also considered. However, in our opinion since the subject site has a history of soil movement, a pile foundation system would offer the most resistance to potential soil settlement and shallow earth movement. 11.1 Pile Foundations - Augercast Piles Cast -in -place concrete piles (augercast) are recommended for foundation support. We recommend that the placement of all piles be accomplished by a contractor experienced in their installation. We estimate pile lengths will be on the order of 17 to 20 feet for a 16 inch diameter pile with an allowable 10 ton vertical capacity, and an embedment of 8 feet into the bearing strata. Pile length estimates , are relative to site grades at the time of our exploration and should be adjusted accordingly if the site is graded prior to pile installation. Pile lengths will be deeper at higher elevations on the property. Allowable design loads may be increased by one-third for short-term wind or seismic loading. Anticipated settlements of augercast pile -supported structures will generally be less than one half inch. 11.1.1 Lateral Pile Capacity The recommended allowable lateral capacity of 16 inch diameter augercast piles (applied at the pile top), assuming a fixed head condition, is 6.5 tons each. The lateral capacities above were determined assuming 0.5 inch of deflection at the pile top with the pile tops fixed to prevent rotation. A factor of safety of 2 was applied to the allowable horizontal lateral capacity. For a 17 foot deep pile, the depth to fixity (maximum moment) has been calculated to be about 10 feet. Moment reinforcement should extend the full pile length. m 11.1.2 Pile Inspections each pile may be adjusted in the field based on required capacity and The actual total length of p y � q p ry ' conditions encountered during drilling. Since completion of the piles takes place below ground, the judgment and experience of the geotechnical engineer or his field representative • must be used as a basis for determining the required penetration and acceptability of each pile. ' Consequently, use of the presented pile capacities in the design requires that all piles be inspected by a qualified representative from our firm who can interpret and collect the installation data and observe the contractors operations. The geotechnical engineer, acting as ' the owner's field representative, would determine the required lengths of the piles and keep records of pertinent installation data. A final summary report would then be distributed, following completion of pile installation. 12.0 FLOOR SUPPORT Floors may be either crawlspace, slab -on -grade, or structural (pile supported). For crawlspace, the soil subgrade should be covered by a plastic moisture barrier. For slab -on - grade or pile supported, the soil subgrade must consist of stiff natural sediments or compacted structural fill as necessary to establish grades. ' Once the soil subgrade has been prepared to the desired grade and to the satisfaction of the geotechnical engineer, the floor should be cast atop a minimum of 4 inches of pea gravel to act ' as a capillary break. The pea gravel should then be covered by a plastic moisture barrier. A 2 inch layer of sand may then be placed atop the moisture barrier to aid in the finishing and curing of concrete and to protect the integrity of the plastic membrane. 1 13.0 UTILITY CONNECTIONS Due to the soft/loose nature of the near -surface soils underlying the site, flexible connections ' between all utilities and the residences are recommended. These connectors should allow up to 6 inches of ground movement. ' 14.0 LATERAL WALL PRESSURES Currently, retaining walls are not planned. However, if retaining walls are to be used, the following considerations should apply. All backfill behind walls or around foundation units should be placed as per our recommendations for structural fill and as described in this section ' of the report. Horizontally backfilled walls which are free to yield laterally at least 0.1 percent of their height, may be designed using an equivalent fluid equal to 40 pounds per cubic foot ' (pcf). Fully restrained, horizontally backfilled rigid walls which cannot yield should be designed for an equivalent fluid of 60 pcf. Surcharges from adjacent footings, heavy construction equipment, floor loads, or sloping ground must be added to the above values. i 15 1 1 1 1 1 The lateral pressures presented above are based on the conditions of a uniform horizontal backfill consisting of imported sand and gravel compacted to 90 percent of ASTM:D-1557 with a 12 inch horizontal blanket drain of washed drain rock immediately adjacent to the wall. Achieving a minimum 90 percent of ASTM:D-1557 compaction using on -site natural silty clay soils may be difficult. A higher degree of compaction is not recommended as this will increase the pressure acting on the wall. A lower compaction may result in settlement behind the wall. It is therefore recommended that wall backfill consist of imported sand and gravel. 14.1 Passive Resistance and Friction Factors Retaining wall footings/keyways cast directly against undisturbed, stiff soils in a trench may be designed for passive resistance against lateral translation using an equivalent fluid equal to 300 pounds per cubic foot (pcf). The passive equivalent fluid pressure diagram begins at the top of the footing, however, total lateral resistance should be summed only over the depth of the actual key (truncated triangular diagram). This value applies only to footings/keyways where concrete is placed directly against the trench sidewalls without the use of forms. If footings are placed on grade and then backfilled, the top of the compacted backfill must be horizontal and extend outward from the footing for a minimum lateral distance equal to three times the height of the backfill, before tapering down to grade. The passive resistance value includes a factor of safety equal to 3 in order to reduce the amount of movement necessary to generate passive resistance. The friction coefficient for footings cast directly on undisturbed, stiff soils may be taken as 0.3. This is an ultimate value and does not include a safety factor. 15.0 DRAINAGE CONSIDERATIONS All perimeter foundation walls and grade beams should be provided with a drain at the grade beam base elevation. Drains should consist of rigid, PVC, perforated pipe backfilled within 1 foot of ground surface with washed drain rock. The size of the drain rock must be greater than the diameter of the pipe perforations. The bottom of the pipe should be set approximately 2 inches below the bottom of the foundation and should be constructed with sufficient gradient to allow gravity discharge away from the homes. Roof and surface runoff should not discharge into the footing drain system but should be handled by a separate tightline drain. In planning, exterior grades adjacent to walls should be sloped downward away from the structures to achieve surface drainage. All drains must be either tightlined to a suitable engineered storm water conveyance system or tightlined to the bottom of slopes. If tightlining drains over slopes, the pipe should consist of a minimum 8 inch diameter HDPE pipe. The pipe must be anchored at the top of the slope and should be routed on the surface of the slope. The anchor should consist of the pipe fastened to a concrete catch basin fitted with an overflow grate. Yard/landscape drains should be provided as necessary. 16 16.0 PROJECT DESIGN AND CONSTRUCTION MONITORING We are available to provide additional geotechnical consultation as the project design develops and possibly changes from that upon which this report is based. This is especially important since periodic monitoring of the site is planned throughout the winter. In addition, no foundation plans were available for the residence at the time our work was completed. We recommend that AESI perform a geotechnical review of the foundation and site plans prior to final design completion. In this way, our earthwork and foundation recommendations may be properly interpreted and implemented in the design. We are also available to provide geotechnical engineering and monitoring services during construction. The integrity of the foundations depends on proper site preparation and construction procedures. In addition, engineering decisions may have to be made in the field in the event that variations in subsurface conditions become apparent. We have enjoyed working with you on this study and are confident that these recommendations will aid in the successful completion of your project. If you should have any questions, or require further assistance, please do not hesitate to call. Sincerely, tASSOCIATED EARTH SCIENCES, INC. .Kirkland, Washington ' Joseph B. Clare, E.I.T. Staff Geotechnical Engineer ' Ronald A. Parker, P.G. Principal G9722 G97224A1 10/1/97 Id - W97 Bruce L. Blyton, P.E. Associate Engineer 1 17 N N N•O J- 00 N c0 0 c} p0 N t0 (alrf}IMI<}1 tl-, V31M,U1 t01c0� J cp 00 O rP 0e �000Nd-c0 o00 N d c0 O N d' c0 00 O -' :•:; I Nn1,0j 101,44 NIc0101d-I °JO a'>t\' v v n o Q\ \ IIII Ill 71 Ill I P E}i \ \ PiANYER \ �10.: ` \ \ LAN0D I E EQ GIN G 4"' r OR r �, i SCARP \ 588155(07('E I I•:1 I I 18'}drAPLE Iat} 18"MAPL EVEi2GRE4EN \ _QV€RH�A� PfJ}YEB ki , 1 ` CEO I PROPOSED 0 HOUSE C I: 1 I i DIlAPIOATED 0)i 11 1 I 1 1", I f '.4 �..I., HOUSE -- t oho 1 tt^C th I I I 1' CApVE ED Ck7N ETE ', l�: I I I I I lu`�1; PATIO r ,1 I III i'.II11 'I �0 I fr fl r/ II Xk I S II'I (� 1 It Itl1 �i�x' I , vvvv,\ ,. �.��i� vV�:, vvty •I I I I 'EB-3 1 I Y 29'405 tI J1�1 i I aa �# ttfl I .GZEB- 14�� xatit,i Lt\�ir\i r,.6.��.�i� rx�i�iiTq Ex�Mil�rr��r �I��T1 'ELT ��S'I'CIGr.il tF�('■' \ \.S } 1 1 t.I-.. 1 DECLbUO S `�'• I �, v� 116-, 16'�k 12"j ! a tEP-3.,,1 1 , :I 11 ACRES I I: V> 1;1 I I I j'1: '1'' r,{. I { k{ f 11 }, I N 'L 11'1 . I .'i 1 r NbTEI ..�. HOG WIREI FEN E ' I. �' ! i .I i.I I BROKEN DqOWN�AND �' `I. / 96 1,11 I 1 1 I' UNDEFINABLE I T,!�(ROUGH DENFE G'.h � t { 8RUAH ..j'^I'c_i : 1 / ",I: L I I h• is n, i i i I i, 1 1 1 1 1 I h i 1 ,J. t 1 { t mr 1 11I Ii1.1 k l 1{I Ia PROPOSED 1 } 11 itb TENSION .1 1, SHED CRACK k _ 1.1 7; I HOUSE �•` { {,^ .I I 1 ( I 1 I EB-2/J 11'p I I �. I I I 'L 1: I I I i I I I I I '. I l ✓♦ � I r �:, i �'1 1 I l 1 1 11 DILAPIDATED .� 1 ! ! SCARP Ul1LITY TENSION t r;4. \ \ \ CRACK I 1 }., BUILDING ))) ''1 19 cPcp\O II i A1 4. , I I I:I ,.I,•1. t 4 1'} 1 i'•1 } �,, �� ~ \ � �.�� \��g /Xi II I i I I I.II I ii,..i t .i'.,} I N88'OJ'4S W 195.16 c{z 1 t t t I I I I I I I I I i rn cO tbOMd' c0000Nd' t0 COON t0 wO"'4-wa00N t I I NI01 I�I� N N M M M M -t t 't ,t n M rfl M M 0 c0 t0 c0 c0 r h r 0 00 000 V��ON� . •.I: : ,:. I'. . h CD o0' co m O, REFERENCE: CRAMER NORTHWEST, INC. SURVEYORS 6 PLANNERS SURVEY -TOPOGRAPHIC SURVEY FOR THERESA ALDRIDOE' DATED 9/4/97. LEGEND EP-1 0 Approximate location of exploration pit EB-1 • Approximate location of exploration borRV NORTH 0 30 60 SCALE IN FEET y � r vpl 1 FIGURE 1 SITE AND EXPLORATION PLAN ALDRIDGE SHORT PLAT EDMONDS, WASHINGTON PROJECT NO. G97224A SEPTEMBER 1997 ASSOCIATED EARTH AMMMSCIENCES, INC 71 N ELEVATION IN FEET W r r IA N 1 3 ~ z W oc = =a c y3 0 w 3� ul w C J cc 0 10 �a 90 a a e Q LV N « C LLI r , ,1 V 1�13 Z w W � � a w 1 f1 Z �' V U oz Nay w o o awcc W V W i \ 1 N a � M O O ci � AA '1 W m� a W L� W LL> rr o z •e HJ Q U T T 1 O 133d NI NOIlVA313 1 EXPLORATION PIT LOG 0 Number EP-1 Soft, moist, brown with gray, silty CLAY to clayey SILT with roots. (Disturbed Fill) 1 15 Medium soft to stiff, moist, bluish -gray, silty CLAY to clayey SILT, brecciated; slickensides; layers of moist to wet, brown, fine sand; upper 1' slide debris. (Possession Drift) 1 10 1 15 BOH @ 15' 1 Note: No seepage; no caving. ' 0 Number EP-2 ' Loose, moist, brown SAND AND GRAVEL mixed with silty clay/silt. (Fill) ' 5 Stiff to very stiff, moist, bluish -gray, clayey SILT to silty CLAY. (Possession Drift) 1 10 15 BOH @ 18' Note: No seepage; no caving. 1 Subsurface conditions depicted represent our observation at the time and location of this exploratory hole, modified by geologic interpretation, engineering analysis, and judgment. They are not necessarily representative of other times and locations. We will not 1 accept responsibility for the use or interpretation by others of information presented on this log. Reviewed By Associated Earth Sciences, Inc. 911 Fifth Avenue,. Suite 100 Aldridge Short Plat Kirkland, Washington 98033 Edmonds, Washington � 1 Phone: 425-827-7701 Project No. G97224A September 1997 Fax: 425-827-5424 � EXPLORATION PIT LOG 0 Number EP-3 Loose/soft, moist, dark brown, silty, fine SAND with roots. (Fill) Loose, moist, brown, medium SAND. (Fill) Loose, moist, reddish -brown, medium SAND with occasional gravel. (Fill) Stiff to very stiff, moist, bluish -gray, silty CLAY. (Possession Drift) BOH @ 18' Note: No seepage; caving. 1 o Number EP-4 S 10 15 Loose, dry, dark brown, silty, fine SAND with occasional gravel, roots, chunks of asphalt. (Fill) Loose, damp, reddish -brown, medium SAND wtih occasional gravel. (Fill) Stiff to very stiff, moist, bluish=gray, silty CLAY; slickensided surfaces; upper 1' slide debris. (Possession Drift) BOH @ 16' Note: No seepage; caving 0 to 8'. ' Subsurface conditions depicted represent our observation at the time and location of this exploratory hole, modified by geologic interpretation, engineering analysis, and judgment. They are not necessarily representative of other times and locations. We will not accept responsibility for the use or interpretation by others of information presented on this log. Reviewed By 1 Associated Earth Sciences, Inc. 911 Fifth Avenue, Suite 100 Aldridge Short Plat Kirkland, Washington 98033 Edmonds, Washington Phone: 425-827-7701 Project No. G97224A Fax: 425-827-5424 September 1997 EXPLORATION BORING LOG Number EB-1 Page 1 of 2 STANDARD PENETRATION ~ a Z W RESISTANCE SEDIMENT DESCRIPTION Q Q =O < Blows/Foot 10 20 30 40 Damp, light brown, silty, fine SAND with trace roots; 8• bottom of sample damp, light brown with gray SILT I with trace fine sand. Damp, brown, silty, fine SAND with lenses of silt with 5 4 trace fine sand; tip of sample damp, reddish -brown I • SAND with some small gravel. Damp, reddish -brown SAND with trace gravel. I 5 • No recovery. (Fill) ,oI • 4 ... �..... ?------------------------------------------?..------.............�...---------- I Moist to wet, light brown, silty, fine SAND; top of sample black fine sandy silt. T 1 8• I I charcoal with Moist, brown, silty, fine SAND: tiny roots observed. 15 I 6• Damp to moist, blue, silty CLAY, plastic. I • 11 I I Moist, blue, silty CLAY, laminated. 20 I I •12 i ` I Moist, blue, silty CLAY to clayey SILT. I 1 i I Moist, blue, silty CLAY to clayey SILT. 25 I I i • 22 I Moist, blue, silty CLAY to clayey SILT. I I i 18• I Moist, blue, silty CLAY to clayey SILT with lenses of fine, oxidized sand; slickensided surfaces observed. 1 22' I • (Possession Drift) I ....................................... Damp to moist, light brown, silty, fine SAND, upper T j i i 70 portion oxidized. (Double Bluff Drift) l Subsurface conditions depicted represent our observations at the time and location of this exploratory hole, modtfled by geologic Interpretations, engineering analysis, and judgment. They are not necessarily representative of other times and locations. We will not ' accept responsibility for the use or Interpretation by others of Information presented on this log. Reviewed By ELI ' Associated Earth Sciences, Inc. Aldridge Short Plat H 911 Fifth Avenue, Suite 100 Kirkland, Washington 98033 Phone: 425-827-7701 Fax: 425-827-5424 Edmonds, Washington Project No. G97224A September 1997 EXPLORATION BORING LOG Number EB-1 Page 2 of 2 SEDIMENT DESCRIPTION F=— o -J Z W Q =) IR 0 STANDARD PENETRATION RESISTANCE Blows/Foot 10 20 30 40 (Double Bluff Drift) I 48A BOH @ 36-1/2' . Note: Slope inclinometer installed. 40 45 50 i 55 j ' I i I s0 I i I i I 65 i ' I � I � i Subsurface conditions depicted represent our observations at the time and location of this exploratory hole, modified by geologic Interpretations, engineering analysis, and judgment. They are not necessarily representative of other times and locations. We will not accept responsibility for the use or Interpretation by others of Information presented on this log. Reviewed By Associated Earth Sciences, Inc. 911 Fifth Avenue, Suite 100 Kirkland, Washington 98033 ' Phone: 425-827-7701 Fax: 425-827-5424 Aldridge Short Plat Edmonds, Washington Project No. G97224A September 1997 1 EXPLORATION BORING LOG Number EB-2 Page 1,of 2 i i 0 Lq STANDARD PENETRATION j=- a Z W RESISTANCE SEDIMENT DESCRIPTION o ¢ 0 Blows/Foot U 10 20 30 40 Damp, brown, fine to coarse SAND with trace fine (Fill) I gravel. ....................................................................................................... Damp, light brown SILT in top of sample; damp, light 5 T 7A gray, clayey SILT to silty CLAY in bottom of sample. l Damp, gray, silty CLAY. (Slide Debris) I �12 Damp, gray, silty CLAY. 10 I 16A Moist, bluish -gray, clayey SILT to silty CLAY. I 6A Moist, light brown, fine SAND in top of sample; moist, 15 10 j bluish -gray, silty CLAY in bottom of sample. i Moist, bluish -gray, silty CLAY; wet, medium SAND in I 130 tip of sample. Moist, bluish -gray, silty CLAY. 20 I I �4 Moist, bluish -gray, silty CLAY; fine sand lense in middle I 3= of sample. 1 Moist, bluish -gray, silty CLAY, medium sand lense in 25 T I 27 I middle of sample. (Possession Drift) 1 i A Damp to moist, light brown, fine SAND at top of sample; I 38A medium sand lower half of sample. 1 30 i Damp to moist, light brown, fine SAND. I i i 73 Damp to moist, light brown, fine SAND. I ; j 65 (Double Bluff Drift) Subsurface conditions depicted represent our observations at the time and location of this exploratory hole, modified by geologic Interpretations, engineering analysis, and judgment. They are not necessarily representative of other times and locations. We will not accept responsibility for the use or Interpretation by others of Information presented on this log. Reviewed By Associated Earth Sciences, Inc. Aldridge Short Plat 911 Fifth Avenue, Suite 100 Edmonds, Washington 'Kirkland, Washington 98033 Project No. G97224A Phone: 425-827-7701 September 1997 Fax: 425-827-5424 III EXPLORATION BORING LOG Number EB-2 Page 2 of 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 SEDIMENT DESCRIPTION H o a z W Q 0 STANDARD PENETRATION RESISTANCE Blows/Foot 10 20 30 40 (Double Bluff Drift) I 62 BOH @ 36-1/2' 40 45 I 50 I � I 55 j I j I I s0 j I j 65 1 I I I I Subsurface conditions depicted represent our observations at the time and locatlon of this exploratory hole, modified by geologic Interpretations, engineering analysis, and judgment They are not necessarily representative of other times and locations. We will not accept responsibility for the use or Interpretation by others of information presented on this log. Reviewed By Associated Earth Sciences, Inc. 911 Fifth Avenue, Suite 100 Kirkland, Washington 98033 Phone: 425-827-7701 Fax: 425-827-5424 Aldridge Short Plat Edmonds, Washington Project No. G97224A September 1997 1 1 1 1 1 EXPLORATION BORING LOG Number EB-3 Page 1 of 2 STANDARD PENETRATION a Z w RESISTANCE SEDIMENT DESCRIPTION a. o Q 0 Blows/Foot rn 0 10 20 30 40 5 Moist, orangish-brown, silty SAND. (Fill) I ♦ Moist, gray, clayey SILT (Slide Debris) 5 T 7♦ Moist, gray, silty CLAY to clayey SILT. I �12 Moist, bluish -gray, silty CLAY with moist, brown, fine 10 I ♦ 14 j sand lenses 4 thick in middle of sample. Moist, bluish -gray, silty CLAY; fine sand lense in T 15 middle of sample. l Moist, bluish -gray CLAY; 6" thick lense of peat with silt; 15 T 128 ♦ j slickenside surfaces. (Possession Drift) 1 134 -------------------------------------------------------------------------------------------------- Damp, light brown, fine SAND. I Damp, light brown, fine SAND; very fine sand to silt lense 20 T j i 30 in middle of sample. 1 Damp, light brown to gray, fine to medium SAND. 1 57 Damp, light brown, fine SAND; moist, brown, fine SAND 25 i ' i in bottom of sample. I I I ' 69 Moist, brown, fine SAND. I 1 I j i 81 Moist, brown, fine SAND. 30 I 71 Moist, brown, fine SAND. I I � s 82 I Subsurface conditions depicted represent our observations at the time and location of this exploratory hole, modified by geologic Interpretations, engineering analysis, and judgment. They are not necessarily representative of other times and locations. We will not accept responsibility for the use or Interpretation by others of Information presented on this log. Reviewed By aD ' Associated Earth Sciences, Inc. 911 Fifth Avenue, Suite 100 'Kirkland, Washington 98033 Phone: 425-827-7701 Fax: 425-827-5424 Aldridge Short Plat Edmonds, Washington Project No. G97224A September 1997 1 1 1 1 1 1 1 1 1 1 1 1 1 I - EXPLORATION BORING LOG Number E13-3 Page 2 of 2 SEDIMENT DESCRIPTION ~ 0 W a Z LLJ ¢ O Q � �� STANDARD PENETRATION RESISTANCE Blows/Foot 10 20 30 40 (Double Bluff Drift) � 64 BOH @ 36-1/2' Note: Slope inclinometer installed. 40 I i i I 45 , i I ' I I i I I 50 I I ' I I 55 j i 60 i � I I i I I i I 65 I i I i I j I I j I i Subsurface conditions depicted represent our observations at the time and location of this exploratory hole, modified by geologic Interpretations, engineering analysis, and judgment. They are not necessarily representative of other times and locations. We will not accept responsibility for the use or Interpretation by others of information presented on this log. Reviewed By ' Associated Earth Sciences, Inc. 911 Fifth Avenue, Suite 100 Kirkland, Washington 98033 ' Phone: 425-827-7701 Fax: 425-827-5424 Aldridge Short Plat Edmonds, Washington Project No. G97224A September 1997 LU7 cl P4 0 z w u o Lu" ci z 0 z P0 i o u u �< w Q z 0 u 9 ;t w 2 20 O (A. _j - cri co 1 1 1 U tog I Ln M W7 ci FILTER FABRIC SECURED TO 2' X 2' 14 GA, WIRE FABRIC EQUAL 2'X2'WOOD OR�II o .EQUIVALENT N 8'- 12' 8' PLACE 3/4-1.5' WASHED GRAVEL IN THE TRENCH AND ON BOTH SIDES OF FILTER FABRIC FENCE ON THE SURFACE, FILTER FABRIC MATERIAL IN CONTINOUS ROLLS. USE STAPLES OR WIRE RINGS TO ATTACH FABRIC TO WIRE. o i i WIRE MESH SUPPORT FETE cu i TO SUPPORT FILTER FAMIC. BURY BOTTOM OF FILTER N ii MATERIAL 8' TO 12' 6' MAX. N LJ 2' X 2' WOOD POSTS OR EQUIVALENT CONTRACTOR/DEVELOPER SHALL MAINTAIN AND REPLACE STRAW BALES TO INSURE PROPER EROSION CONTROL. /890-199v CITY INSPECTION REQUIRED ON ALL ER❑SION CONTROL METHODS BEFORE OTHER WORK CAN BEGIN. REVISIONS STANDARD DETAIL FILTER FABRIC FENCE FILTRATION SYSTEMS DATE 7/24/01 SCALE NTS I DWG NO. Ell - j. BINDING WIRE OR ii TWINE EXCAVATE TRENCH 8' DEEP -�--I� WHERE STRAW BALES WILL ,T---III---�� BE PLACED AND STAKE BALES. COMPACTED SOIL TO II PREVENT PIPING � -- II---III---III-- I I ---I I III— '''--rl I I---I- --I I I—� rTT---I --' I I---� --I I I--"-1 11 CROSS SECTION OF A PROPERLY INSTALLED STRAW BALE BARRIER TWO STAKES PER BALE TO MAINTAIN POSITION r � r i if. J ri STRAW BALES AS REQUIRED. 11 rye //l�6fr/ % / 1=1I1=1 - . y % I 1 y V PROPER PLACEMENT OF STRAW BALE BARRIER IN A DRAINAGE WAY CONTRACTOR/DEVELOPER SHALL MAINTAIN AND REPLACE STRAW BALES TO INSURE PROPER EROSION. CONTROL. CITY INSPECTION REQUIRED ON ALL EROSION CONTROL METHODS BEFORE OTHER WORK CAN BEGIN. �- C I.T.Q. REVISIONS STANDARD DETAIL APPRQVU BY BATE STRAW BALE DAM FILTRATION SYSTEMS 1890-1991D DATE 7/24/01 SCALE NTS DNrc No. E1.1.1 T,y S'C6 0o- qN r,yr�,yj� 1p M'9l- O,c` F � d F�AO`r0� y�cFd `r01Ot`,r O ' MIN, RADIUS 4'-8' QUARRY SPALLS 8'-12' MIN. DEPTH PROVIDE FULL WIDTH OF INGRESS/ EGRESS AREA CONTRACTOR SHALL MAINTAIN. TEMPORARY CONSTRUCTION ENTRANCE DURING THE CONSTRUCTION PERIOD. CITY INSPECTION REQUIRED ON ALL EROSION CONTROI MEASURES BEFORE WORK CAN BEGIN. /d9Q-19yv REVISIONS STANDARD DETAIL STABLIZED CONSTRUCTION ENTRANCE DATE 7/24/01 SCALE NTS DWC ND. E 1.2 7/8WASHEr FABRIC N. CATCH BASIN `�\'', \ j'" •.• sip/ v b wvr PLACE FILTER FABRIC BETWEEN FRAME��y%' AND GRATE. PLACE 7/8' WASHED GRAVEL 3-4 INCHES HIGH AROUND CATCH BASIN TO FILTER WATER. STRAW BALES MAY BE USED IN CERTAIN CIRCUMSTANCES (SEE DETAIL E1.1.1) UPON APPROVAL OF CITY ENGINEER OR HIS REPRESENTATIVE. THIS APPLICATION SHALL BE MAINTAINED AT ALL TIMES DURING CONTRUCTION PERIOD. CITY INSPECTION REQUIRED ON ALL EROSION CONTROL MEASURES BEFORE WORK CAN BEGIN. ldgo-199v REVISIONS STANDARD DETAIL P7PRovu BY DATE TEMPORARY SEDIMENT TRAP FOR CATCH BASINS DATE 7/24/01 1 SCALE NTS owc No. E1.3 .—Tmil S-1 -u—U 1—d Sum sainjonils joilaaa(i jo uoiliToma(i E- Es Ex !;UOA74-j@uu@q LU x LU 4? 6 -4 045 gqq 16" : FF z Q qp� 4 qk A M ---------------- — — — — — -- — - - - - - - - - MOIDIVIMAW 9M v k ;. ?D I Ss 2 �h A. -0 1 pq W I �-q 5 5, H� Igo. a. its. 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