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15631 75TH PL W.PDF15631 75TH PL W BLAII ADDRESS: TAX ACCOUNT/PARCEL NUMBER:. ©a 5-13 3 ©coo Zso 3 BUILDING PERMIT (NEW STRUCTURE): < ` l �10 / COVENANTS (RECORDED) FOR:1�0I-/' ��/TIGfi�}�[� zlD1y�0d` 80 Mold RAt%441aj 72M1052 W IM, M917� 9119SZOO191 CRITICAL AREAS:- / ! DETERMINATION: ❑ Conditional Waiver Study Required ❑ Waiver DISCRETIONARY PERMIT #'S: DRAINAGE PLAN DATED: PARKING AGREEMENTS DATED: /�/ EASEMENT(S) RECORDED FOR: jgU/T (�1 /yM PERMITS (OTHER): PLANNING DATA CHECKLIST DATED: SCALED PLOT PLAN DATED: 3��� SEWER LID FEE $: LID #: 210 SHORT PLAT FILE: LOT: BLOCK: SIDE SEWER AS BUILT DATED. ( SIDE SEWER PERMIT(S) #: 0316 GEOTECH REPORT DATED: IL? I / STREET USE / ENCROACHMENT PERMIT #: FOR: // WATER METER TAP CARD DATED: (O 2- OTHER: ✓ 1 & w,9 I lc 1� Gee /Fe 'd'�o°� ae /401o �zb! /S86 VlvlfAW 70g�/ef AiL. raNO lac Ae.JAj1/-"Cv1a L:ITEMP\DSTs\Forms\.Street File Checklist.doc ,' � > � •�;r:�c-...�.ra'�+K,.,.�rne.rct' xr; CITY OF EDMONDS; �, SIDE P T 189p.19�° PUBLIC WORKS DEPT. PERMIT N2 8316 Address of Construction: JI ?L A Property Legal Description (Include all easements): �� ���- L oT S �- S ffR7��VTC1rP- - Y • r Owner and/or Contractor: State License No. 19e-516W 6t -/N Building Permit No. -�•� 7 .Single Family ❑ Multi -Family (No. of Units ) ❑ Commercial ❑ Public w Invasion into City Right-of-Way:p�No - ❑ Yes RW Construction Permit No. Cross other Private Property:PZo ❑ -Yes Attach legal description and copy of recorded easement 0 &� & he / q I , I certify that I have read and shall comply with all city requirements Date as indicated on the back of the Permit Card. * CALL DIAL -A -DIG (1-800-424-5555) BEFORE ANY EXCAVATION OFFICE USE ONLY * FOR INSPECTION CALL 771-3202, PUBLIC WORKS DEPT. Permit Fee: �LJ� Issued By Trunk Charge: 2-S r Date Issued: Assessment Fee: Receipt No.: �¢3� Lid No.: 2/z Partial Inspection: Date Initial Comments Reason Rejected: Final Inspection Approved: Date �� I Date Initial ** PERMIT MUST BE POSTED ON JOB SITE ** White Copy: Pile Green Copy: Inspector Buff Copy: Applicant Revised 3/90 0 V) w 04 am a, 9; M b0; O I, z P4 w 0 U 04 w 0 O z U 0 a w 0 z E-� O a z O E� a U w A a d c� w f'n e W OC u') 0 0 0 a O `P� ON, r 4CC'9f2- DETENTION VIORKSHEET *DARD DRAINAGE PLAN UPPER CATCH DETENTION PIP!' LFNG�R ELELm BASIN (YfiNT )� SAS N, 2' mAx COVER CO*ITROL'� SLOPE+LIP i4, .� ✓ -' F TO 011T LE T (RI PRAP OR RUNOF F SPREADER ._ SYSTEM CROSS SECTION 2' s 2' a !o" VE=P, A=6" SPALLS (oaeow&-) 2'.. 2' .c 3' DEEP, V4'— CRUSµED ROCK FROM ? OUTLET CONTROL WASHED GRAVEL FROM eT 01 CONTROL RIPRAP OUTLET OUTFLOW TRENCH, MIN 10' LONG, TOP 4 A" PERF PIPE -M Be L-EVEL " PFRF PIPE WITH CAPS RUNOFF SPREADER OUTLET FOOTING DRAINS SHALL NOT BE DETENTION SYSTEM for location plan by phone date DESIGN DATA System Imperm Pipe Pipe Orifice Number Area Diam Length Diameter NOTES 1. Call Engineering.Division (771-3202) for prebackfill and :final inspections. 2. Responsibility for operation and maintenance of drainage systems on private property is the responsibility of the property owner(s). Material accumulated in the storage pipe must be flushed out and removed from catch basins to allow proper operation. The outlet control orifice must be kept open at all times. a a ALa w: D IVIAR CITY OF gd�t$'Kibs Page 9 of 9 CONNECTED TO THE DRAINAGE SYSTEM DETENTION RKSHEET :. UPPER C ATGH BASIN DETENTION Pipe LENGTH SIX TOM (VfiNT )` eqs� = t' MIN, 2' Max COVER ---f �x SLOPE+ SYSTEM CROSS SECTION OVTLGT CONT;toe 4" 'TO OUTLFT (NPRAP OR RUNOFF SPREADER ._ tiiV G 2' . 2' . &P DEEP, 4"- &" SPALLS (owcOWL) 6f-2' - 3" DEEP, "� CRUSHED ROCK -0105 Ap- FROM 0� OL?'LPT CON-rROL RIPRAP OUTLET WELSHED &RAVEL OUTFLOW TRENCH, MIN 10' LONG, TOP It, 4" PERF PIPE TD BE LEVEL FROM OUT&-EEr CONTROL-+-�-� 4 PERF PIPE WITH CAPS RUNOFF SPREADER OUTLET FOOTING DRAINS SHALL NOT BE �WDARD DRAINAGE PLAN DETENTION SYSTEM for location plan by phone date DESIGN DATA System Imperm Pipe Pipe Orifice Number Area Diam Length Diameter NOTES 1. Call Engineering.Division (771-3202) for prebackfill and final inspections. 2. Responsibility for operation and maintenance of drainage systems on private property is the responsibility of the property owner(s). Material accumulated in the storage pipe must be flushed out and removed from catch basins to allow proper operation. The outlet control orifice must be kept open at all times. rVal a 1FAN 9A rJ i •` V'9 AMA r D r l _ CITY O F diffmcr S Page 9 of 9 CONNECTED TO THE DRAINAGE SYSTEM C' I JMk� J CONSULTING ENGINEERS Project Number 1966 20 March, 1995 Z m y w W .o Z yJ W W o Z W Z �W° U) • • U) Z N _W o Z 0 ¢ O AWN J W Q LU O Z U) W O Z N � 0 N _W 0 7 (~A W Z Z W a O Qom; W J Z Q > D Z Iu 0 a W c�oW U D W W W a (n Z (n Z 3 Z O Z Z Y W 0Ir U W I = U) R a w U C0 Z o 0 ~ W WALL Z0-d O a m Z x g W W o 0 Z o U. J Z y :) m J O D O IL (A V) page 1 of 3 pages CLIENT David and Jody Spiro ;`T ADDRESS 15631 75th Place W y, Edmonds, Washington 98026# M1�✓`wY 1f;l� % 7 REFERENCE Proposed lap pool r`y ro�A SUBJECT Geotechnical engineering. INTRODUCTION On 28 June 1994, during a telephone conversation with Dale C. Hemphill, David Spiro authorized HEMPHILL CONSULTING ENGINEERS (HEMPHILL) to conduct geotechnical .engineering for the proposed lap pool to be located approximately as shown in Figure 1. The, purpose of the geotechnical engineering is to review the geotechnical report for the residence . dated 10 December 1990, and to present geotechnical recommendations for the construction of the pool. INVESTIGATION The -proposed lap pool will be approximately 12 feet wide, 44 feet long, and 4 to 6 feet deep. The pool will be located approximately as shown in Figure 1 between the house and the 35 foot setback from the west property line. A test boring conducted near the pool during the investigation for the house revealed that the 15 feet under the proposed pool is composed of wet medium dense silty fine sand. The upper soils that will be excavated for the pool are composed of wet loose gravely sand. 4041 WEST LAKE SAMMAMISH PARKWAY SOUTHEAST • BELLEVUE • WASHINGTON • 98008 • 206 6441080 I v 0 LIVING CL 7 0 z 0 LLJ x DINING NOOK DECK 0 -i 0 a. LLI 01- w D LL aaa� ��aa�+aor9ov • Project Number 1966 20 March, 1995 page 2 of 3 pages CONCLUSIONS & RECOMMENDATIONS HEMPHILL concludes that the. soils under -the pool will be capable of supporting the loads, considering that the 100 to 120 pcf soils will be replaced with 60 pcf water, and that the pool loads will be spread out over the entire base of the pool for maximum bearing pressures of 360 psf. Medium dense sandy soils can support minimum loads of 1000 psf, and they presently support a minimum of 600 psf. During the construction of the house the slope from the house to the railroad was considered to be potentially unstable under unusual storm or seismic conditions. The construction of the house improved the stability of the slope by installing retaining walls, deep piles, and drainage. The installation of the pool will also improve the slope stability by removing approximately 400,000 pounds of soil and adding 200,000 pounds of water at the head of the slope, the most critical area, and by installing additional drainage. Jis stability of the lower portion of the will be improved when that parc developed. Because of the wet conditions encountered while conducting the boring, HEMPHILL recommends that the pool be lined with drainage, as shown in Figure 2, to lower the adjacent water levels, and to prevent floating of the pool. Also to prevent the pool from damming any drainage from the east . slope. The drainage can, be composed of several inches of clean drainage gravel around the sides and bottom 'of the pool. The drainage gravel should be surrounded by filter fabric between the gravel and the adjacent soils to prevent the infiltration of the adjacent soils into the gravel, preventing clogging of the drainage. system and voids around the pool. UrE-'1PrIrL L !!, ::::::: ::::::::: : : ......... ;::: ......... . ...... t........ ........ _..................................... T ....... ............. _...._........ .. ...... .... ....... ....... ....... Z . ...... .............................. ....................................... .... ...... : .. ... ... ... W W......: !: :::: ::::::::: �........ ................................ ...................:...... ..... . ....: ................. ...:........ . . .. ... ......... LLJ . . .::::: a ...... ::::: Q.:::::::V)... ...... .... ® � � ................................. .. .. I r, . . . . . . . . . . . . . � m . (n Q......... _. . . . Ww..... . m --- ......;. :::::::i::::: ::: a J ::::::: ....: :.. ............... ...:.:....:...: ...................................:...:_..:... ......................... O .................. i . ............ m . .. . ......... ... ...! z ......... :::::: ::::::::f::::::::: :::::::::�:::: O w ......... �.... CL o 0.::::::::a.... — -- :::::: .... 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':::::::::'.::::::::.!.. �m o �......... �....... :....................... ... .: ..... _........:...:..:._::... :... :... :... :........... .............................. ... .... :.............. _..................... ...... ..................... .. 1.................. • Project Number 1966 20 March, 1995 The pool drainage system should.. be connected to a gravity outlet drain to conduct any intercepted groundwater or leaking water to the roadside drain ditch as shown in Figure 2. Any intercepted water will be minimal, and will have little or no impact on the drainage ditch. Crushed rock can be placed at the outlet of the drain pipe into the drain ditch -to reduce the velocity of any water and to prevent any scouring. The pool can be located anywhere between the deck footings and the 35 foot setback. If the excavations for the pool'are within a 450 line of influence of the deck footings, then the deck should be supported with temporary supports placed beyond the 450 zone of Dale C. Hemphill P.E. Registered Engineer No. 14777 State of Washington page 3 of 3 pages influence. If necessary the existing deck footings might be replaced with relocated supports approved by HEMPHILL. HEMPHILL should verify that the soils and groundwater conditions. are as anticipated, and to present alternative recommendations if conditions are different. HEMPHILL concludes that if the pool is constructed in accordance with the plans and with recommendations presented in this report, and with any recommendations by HEMPHILL at the time of construction, that the pool will be safe, and the stability of the slope will be improved. G • HE1l� v� of WASy/ '�O Fcr� S,to NAL I EXPIRES 17 FEBRUARY 1996 1 �GIf.�D/Y0,41f fID�D L \ I c 'Oti rj �r j I Q rn -o S G7 F 8 XDZQ DNIUIQ O r JN IW_ DMIAI'I I tv I r-- MS a Dp .1ER, • z N � w N 0 W Z O F 2 J H W �?� W 0Z�W Z �W° �XU) • W z N W o Z o a o �'- L a Z W ►Q- O fn J W O o N • U) W 0 ~ N - Z (A W Z W 0 0 Z Q D z W C� O w .. o 0 W ZPo WWI W a v� z v) Z a Z O Z Z F W o Z � U ~ 0 FI- N W Z Q W U N Z O o ~ W WtL Zo.o a a gZ x W W zp Q z oWW D� 7 m J O O LL. fn fn • • • CONSULTING ENGINEERS Project Number 1966 20 March, 1995 CLIENT David and Jody Spiro ADDRESS 15631 75th Place W : Edmonds, Washington 98026 REFERENCE Proposed lap pool SUBJECT Geotechniical engineering INTRODUCTION On 28 June 1994, during a telephone conversation with Dale C. Hemphill, David Spiro authorized HEMPHILL CONSULTING ENGINEERS (HEMPHILL) to conduct geotechnical engineering for the proposed lap pool to be located approximately as shown in Figure 1. page 1 of 3 pages cc� [ IAR 2 7 r The purpose of the geotechnical engineering is to review the geotechnical report for the residence dated 10 December 1990, and to present geotechnical recommendations for the construction of the pool. INVESTIGATION The proposed lap pool will be approximately 12 feet wide, 44 feet long, and 4 to 6 feet deep. The pool will be located approximately as shown in Figure 1 between the house and the 35 foot setback from the west property line. A test boring conducted near the pool during the investigation for the house revealed that the 15 feet under the proposed pool is composed of wet medium dense silty fine sand. The upper soils that will be excavated for the pool are composed of wet loose gravely sand. 4041 WEST LAKE SAMMAMISH PARKWAY SOUTHEAST • BELLEVUE . WASHINGTON . 98008 • 206 644 T080 " Project Number 1966 20 March, 1995 page 2 of 3 pagesxv� n �t� CONCLUSIONS &RECOMMENDATIONS HEMPHILL concludes that the soils under the pool will be capable of supporting the loads, considering that the 100 to 120 pcf soils will be replaced with 60 pcf water, and that the pool loads will be spread out over the entire base of the pool for maximum bearing pressures of 360 psf. Medium dense sandy soils can support minimum loads of 1000 psf, and they presently support a minimum of 600 psf. During the construction of the house the slope from the house to the railroad was considered to be potentially unstable under unusual storm or seismic conditions. The construction of the house improved the stability of the slope by installing retaining walls, deep piles, and drainage. The installation of the pool will also improve the slope stability by removing approximately 400,000 pounds of soil and adding 200,000 pounds of water at the head of the slope, the most critical area, and by installing additional drainage. The stability of the lower portion of the slope will be improved when that parcel is developed. Because of the wet conditions encountered while conducting the boring, HEMPHILL recommends that the pool be lined with drainage, as shown in Figure 2, to lower the adjacent water levels, and to prevent floating of the pool. Also to prevent the pool from damming any drainage from the east slope. The drainage can be composed of several inches of clean drainage gravel around the sides and bottom of the pool. The drainage gravel should be surrounded by filter fabric between the gravel and the adjacent soils to prevent the infiltration of the adjacent soils into the gravel, preventing clogging of the drainage system and voids around the pool. 1 14, rP-�HrIrL LE . . . . . . . . . . . . .................................... ............................. . . . . . . . . . . . . . . . . . . . . ........ .. ........ .. ... . ..... ...... ...... ...... . . . . . . . . . . . . I . . . . . . . . . . . ........ ........ ... . ... ....... ........ ......... • . . i ......... ......... .... H.1 ........ ... Ui' .... ... CN ... ..... ... ............. ... ............ * ............... .... ..... .. . ... ......... ............. ............. .... . ......... 3 ........ ......... ...... . .. ...... .. ... ... ......... ... ... .... ........ .. ..... .. ... ........ . ........ .... ... ... ....... ........ .. .. ........ . .......... .......... .. .... ....... ............................... ... .... ... ... ....... .... ....... ... .... .... . ........ ..... ....... ........ . ......... . ..... ......... ... ... ...... Lli ........ I . . ................... ....... .. . ...... ....... ................... ... ....... ...... ........... ... ........ . ...... . . . . . . . . . . . . . . . ....... ........ ICL ... ....... . ........ z ...... .. ... < ... I ........ < ........ =) ......... ... ... ... ....... ........ EEO EM ty . . . ... .......... .... o . .. ......... ................ . ..... .............. . .. ...... ... ... ....... ........ ........ LL ... ....... ... ....... < . ......... .............. ........ ......... ... ........................... ... ....................... ..... ... . ....... ... ........ ................ . IL . ................................ ... .................. .......... ........... i. ... .............................. :' ' ' ' ''o. .. ....0......... ........ J qm I... . .. ........ ......... .. ......... .. . ......... .... CL ........ ......... .......................... ............................ ....................................... ............ . .... ..... . .... ......... ........ ...... ........ ......... .. ....... .... ....... . ......... ........ .......... .. ............................. ............ ... ....... . ................... ........ .... ....... uj .......... ........ . . . . . . . . . . . . . . . . . . . . . . . . ........ Cl*4 . . . . . . . . . . . . . . . . . . . . . . . . J :.Q Au . . . . . . ......... ......... ........ ........ ......... ........ z ........ .... ......... ............................. ........................................... ........ ...LL..... Via:...:...:.. ........ .................... ......... ......... oo... ......... ......... ......... ........ ......... .... ... ..... ......... ......... ......... ... ... .................... . ..... * ....... .. ................... ........ ...... uj: ..... . ...... ....... ........ . .... ............. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ......... ..... ... ......... ......... ......... . ......... ......... .............................. ... ... .................. ..': ........................ ......... ...... ......... ... ....................................................... . .................. ................... ....... I......... .. ......... ...... .. ... ... ..... ......... ....... . ......... ......... ....... . ...... ... ...:...:...:...:...:..I.:...:...:...:...:...:...:...:...:... li"*'*"*'*' *I ... ... ....... ........... .... .. ......... . ......... . ....... . .......... ......... ....... . . . . . . . . . . . . . . . . . ................ ...................... ..................... ...... .......... ............................... . . . . . . . .. . . ......... 0 ....... ................. U) o ......... ... ............ . . . .. . ..:...................:.......:...:.. . ......... ......... .. ......... . ......... .......................... ... .... . ......... Project Number 1966 20 March, 1995 The pool drainage system should be connected to a gravity outlet drain to conduct any intercepted groundwater or leaking water to the roadside drain ditch as shown in Figure 2. Any intercepted water will be minimal, and will have little or no impact on the drainage ditch. Crushed rock can be placed at the outlet of the drain pipe into the drain ditch to reduce the velocity of any water and to prevent any scouring. The pool can be located anywhere between the deck footings and the 35 foot setback. If the excavations for the pool are within a 450 line of influence of the deck footings, then the deck should be supported with temporary supports placed beyond the 450 zone of Dale C. Hemphill P.E. Registered Engineer No. 14777 State of Washington page 3 of 3 pages influence. If necessary the existing deck footings might be replaced with relocated supports approved by HEMPHILL. HEMPHILL should verify that the soils and groundwater conditions are as anticipated, and to present alternative recommendations if conditions are different. HEMPHILL concludes that if the pool is constructed in accordance with the plans and with recommendations presented in this report, and with any recommendations by HEMPHILL at the time of construction, that the pool will be safe, and the stability of the slope will be improved. G. HE�� of WA sy7 �� Cl) x� �tr 14777 ��� �PFCISiEREp C� �'Sf�NAL �G I EXPIRES 17 FEBRUARY 1996 1 H1E,�rPHrIr� L • RECEIVE* JUN 0 2 1995 Iff cm June 1, 1995 HWA Project No. 95084-200 City of Edmonds d - 250 5th Avenue North Edmonds, Washington 98020 Attention: Mr. Kirk Yurish Subject: CRMC.AL AREA STMY - PEER REVIEW Spiro Residence Pool Addition 15631 75th Place West Edmonds, Washington BONGWEST & ASSOCIATES. INC. Geotechnical Engineering Hydrogeology Geoenvironmental Services Testing & Inspection Reference: Proposed Lap Pool, Geotechnical Engineering, by Hemphill Consulting Engineers, dated March 20, 1995. Dear Mr. Vuush: In accordance with your request, Hong West & Associates, Inc. (HWA) has completed a geotechnical peer review associated with the proposed new swimming pool construction at 15631 75th Place West in Edmonds, Washington. As part of this study, we visited the site and reviewed the consultant's methodology, conclusions, and recommendations as summarized in the report referenced above. Particular emphasis was placed on recommendations relating to the City of Edmonds Critical Areas Ordinance (Ord. No. 2874, rev. No. 3014). In addition to the referenced report, we reviewed the following documents: 1) Geotechnical Engineering for the Proposed Spiro Residence, to be Located at 15631- 751h Place West, by Hemphill Consulting Engineers, dated December 10, 1990. 2) Addendum to Geotechnical Report, Proposed House, Located at 15631 75th Place West, Meadowdale, by Hemphill Consulting Engineers, dated December 24, 1990. 3) Preliminary Surficial Geologic Map of the Edmonds East and Edmonds West Quadrangles, Snohomish and King Counties, Washington, by M. Smith, dated 1975. 4) Edmonds Landslide Hazard Map, by GeoEngineers, Inc., 1984. 19730-64th Avenue West Lynnwood, WA 98036-5904 Tel. 206-774-0106 Fax 206-775-7506 June 1, 1995 HWA Project No. 95084-200 The consultant's report (March 20, 1995) references document No. 1 above and relies on the subsurface investigation therein to formulate recommendations for the proposed lap pool. Documents No. 3 and 4 indicate that the subject site is within the mapped boundaries of the Meadowdale Landslide, which occurred as a result of an earthquake in 1947. Methodology The City has requested we review the consultant's methodology and evaluate whether the subsurface exploration, laboratory testing, and analysis was sufficient to adequately address slope stability concerns, drainage characteristics, erosion potential, and to provide recommendations for site development. Based on our review, it is our opinion that the subsurface investigation performed in 1990 was adequate to characterize the soil and groundwater conditions in the area of the proposed pool addition. It is our further opinion that the consultant's 1990 and 1995 investigations provided sufficient data to support appropriate analyses and prepare recommendations for site drainage, erosion control, slope stability, and general site development. Critical Areas Ordinance Steep Slope Hazard According to the City of Edmonds Critical Areas Ordinance, a Steep Slope Hazard is any slope with an inclination of 40 percent (2.SH:lV)-or greater, measured over at least 10 feet of elevation change.. For such slopes, a buffer of 50 feet is required. Building setbacks from the edge of the buffer must be a minimum of 15 feet. A slope exists immediately west of 75th Place West which may meet the requirements for a steep slope hazard. The proposed swimming pool setback is 35 feet from the front property line, which is approximately 70 feet from the top of this slope. The setback is therefore within the requirements of the ordinance. It is our opinion that the recommended setback is reasonable. Landslide Hazard The Critical Areas Ordinance defines a Landslide Hazard Area by several criteria, one of which is "any area which has shown movement during the last 10,000 years." The ordinance also refers to the Edmonds Landslide Hazard Map (document No. 4, above) for classification of Landslide Hazard Areas. For a site classified as a Landslide Hazard, a Critical Area Study must be prepared which shows compliance with the following two conditions: 950"IDOC 2 HONG WEST & ASSOCIATES, INc. June 1, 1995 • • HWA Project No. 95084-200 1) The proposed development will not decrease the slope stability on adjacent properties; and 2) The landslide hazard is eliminated or mitigated such that the site is "stable," as defined in City of Edmonds Ordinance 2661. For landslide hazards from deep- seated failures, which cannot be realistically eliminated or mitigated, the definition of stable is "areas classified as having a probability of earth movement of 30 percent or less within a 25-year period. The City of Edmonds has requested HWA to deternrine whether the referenced report meets. the requirements of a Critical Area Study. As previously mentioned, the site lies within the boundaries of a relatively recent landslide and therefore is classified as a Landslide Hazard Area. In our opinion,. the consultant has adequately addressed items No. 1 and 2 above. Regarding item No. 1; the consultant has clearly stated that the proposed improvements will improve slope stability by reducing loading and improving subsurface drainage. In our opinion, the consultant's recommendations for subsurface drainage are appropriate. In addition to groundwater drainage, the drain system should serve as an interceptor for possible pool leakage or overflow. We agree with the recommendation for a filter fabric encasing the drainage aggregate. We also agree that a geotechnical consultant should observe the pool excavation, which will allow for field changes to the drainage system, as conditions warrant (e.g., higher capacity drains if substantial groundwater is encountered). We agree with the need to control erosion at the outlet of the tightline drain. Regarding item No. 2; the Edmonds Landslide Hazard Map shows a probability of 30 percent for earth movement in the next 25 years for the subject site. The consultant's report predicts improved site stability from the proposed pool addition. Therefore, requirement No. 2 appears satisfied by the combination of the consultant's report and the Edmonds Landslide Hazard Map. Summary It is our opinion that the referenced report meets the requirements for a Critical Area Study as specified in the City of Edmonds Critical Areas Ordinance. It should be noted that the scope of services performed by HWA was limited to a site reconnaissance and review of the referenced documents. Field studies and/or verification of calculations were not performed; accordingly, we can offer no assurances regarding the performance of the site. In addition, the services performed consist of professional opinions made in accordance with generally accepted geotechnical engineering principles and practices. 95084-2.E= 3 HoNG WEST $ AssocrATEs, INc. June 1, 1995 • 0 HWA Project No. 95084-200 We appreciate this opportunity to be of service. If you have any questions, or if we can be of further service, please do not hesitate to call. Sincerely, HONG WEST & ASSOCIATES, INc. Geotechnical Engineer ADM:SM:adm 95084-2.DOC 4 HONG WEST & ASSOCIATES, INc. • CA* NO. f 4- f bL( Critical Areas Checklist Site Information (soils/topography/hydrology/vegetation) 0 - " r kX\ 1. Site Address/Location: 2. Property Tax Account Number: _C^\3 O0 0 a• S — 3 0 3. Approximate Site Size (acres or square feet): 4. Is this site currently developed? X yes; no. CL If yes;.how is site developed? S 1 Vcl ��1Wll H laF-�U /� 5. Describe the general site topography. Check all that apply. Flat: less than 5-feet elevation change over entire site. Rolling: slopes on site generally less than 15% (a vertical rise of 10-feet over a horizontal distance of 66-feet). Hilly: 15% less 30% slopes present on site of more than and than ( a vertical rise Fri of 10-feet over a horizontal distance of 33 to 66-feet). r 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: 0 ; Approx. Depth: 7. Site contains areas of seasonal standing water: 0 ; Approx. Depth: What season(s) of the year? 8. Site is in the floodway '✓a floodplain N of a water course. 9. Site containsU creek or an area where water flows across the grounds surface? Flows are year- round? 0 Flows are seasonal? (What time of. year? ). 10. Site is primarily: forested ;meadow ;shrubs ; mixed urban landscaped (lawn,shrubs etc) 11. Obvious wetland is present on site: U For -City. Staff Use Only- 1. Site is Zoned? '2CJ 2.. . SCS mapped. soil type(s)? yllz?w t 1pr ���� j` l"T�?J>�✓�iLC _ 3.' " Wetland inventory or C.A. map indicates wetland present on site? N a 4. Critical Areas inventory or C.A. map. indicates Critical Area on site? Y� S: 5ife within designated earth subsidence landslide hazard area. 6. Site designated on the Environmentally Sensitive Areas Map?pj DETERMINATION STUDY REQUIRED CONDITIONAL WAIVER WAIVER Reviewed by:------/=t4,libd Planner D to c 04�ev i o (L s S EPA atie U. V4L->) r40e -6c. 61 i L 7- Rev OW29M T u,��Sp„� eH'�n E6ide� i9 %AT/O,ei — ago_199 City of Edmonds Critical Areas Checklist The Critical Areas Checklist contained on this form is to be filled out by any person preparing a Development Permit Application for the City of Edmonds prior to his/her submittal of a,development permit to the City. The purpose of the Checklist is to enable City staff to determine whether any potential Critical Areas are or may be present on the subject property. The information needed to complete the Checklist should be easily available from observations of the site or data available at City Hall (Critical Areas inventories, maps, or soil surveys). An applicant, or his/her representative, must fill out the checklist, sign and date it, JULZ 9 194 PER I!T CC1UNTER and submit it to the City. The City will review the checklist, make a precursory site visit, and make a determination of the subsequent steps necessary to complete a development permit application. With a signed copy of this form, the applicant should also submit a vicinity map or plot plan for individual lots of the parcel with enough detail that City staff can find and identify the subject parcel(s). In addition, the applicant shall include other pertinent information (e.g. site plan, topography map,. etc.) or studies in conjunction with this Checklist to assist staff in completing their preliminary assessment of the site. 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). Owner / Applicant: Name Street Address qLMLA�-sr) -C S 7 City, State, ZIP o g 0 2 � Phone Signature Date Applicant Representative: t' 0-5 - ��ASy-�Z 'ray -is Name �Au- l u.E- Street Address A'VA-LIF."sNk 3bS-333� City, State, ZIP Phone ' 29 Signature Date .890-19y June 6, 1995 CITY OF EDMONDS 250 - STH AVE. N. 4 EOMONDS, WA 98020 • (206) 771-0220 • FAX (206) 771-0221 COMMUNITY SERVICES DEPARTMENT Public Works • Planning • Parks and Recreation • Engineering David Spiro 15631 75th Pl. West Edmonds, WA 98026 Re: Critical Area study for swimming pool Dear Mr. Spiro: LAURA M. HALL MAYOR We have received the critical area study peer review for your swimming pool from Hong West Associates, Inc. After reviewing their analysis and other data in our files we have determined that the study satisfies the requirements of the Critical Area Study. I have spoken to the Building Division regarding the status of your permit. They are still in the process of reviewing the recent data provided by Hong West and other information. When they have completed their review they will contact you. If you have any questions regarding the status of your permit please contact the City Building Official, Jeannine Graf. Sincerely, Kirk J. Vinish Project Planner • Incorporated August 11, 1890 • Sister Cities International — Hekinan, Japan • 7LI 1 June 1, 1995 HWA Project No. 95084-200 City of Edmonds 250 Sth Avenue North Edmonds, Washington 98020 Attention: Mr. Kirk Vuush *RECEIVED J U N9 0 2 1995 PERW COUNTER Subject: CRITICAL AREA STUDY - PEER REvIEw Spiro Residence Pool Addition 15631 75th Place West Edmonds, Washington U �1 BONGWEST &ASSOCIATES, INC. Geotechnical Engineering Hydrogeology Geoenvironmental Services Testing & Inspection Reference: Proposed Lap Pool, Geotechnical Engineering, by Hemphill Consulting Engineers, dated March 20, 1995. Dear Mr. Vinish: In accordance with your request, Hong West & Associates, Inc. (HWA) has completed a geotechnical peer review associated with the proposed new swimming pool construction at 15631 75th Place West in Edmonds, Washington. As part of this study, we visited the site and reviewed the consultant's methodology, conclusions, and recommendations as summarized in the report referenced above. Particular emphasis was placed on recommendations relating to the City of Edmonds Critical Areas Ordinance (Ord. No. 2874, rev. No. 3014). In addition to the referenced report, we reviewed the following documents: 1) Geotechnical Engineering for the Proposed Spiro Residence, to be Located at 15631 75th Place West, by Hemphill Consulting Engineers, dated December 10, 1990. 2) Addendum to Geotechnical Report, Proposed House, Located at 15631 75th Place West, Meadowdale, by Hemphill Consulting Engineers, dated December 24, 1990. 3) Preliminary Surficial Geologic Map of the Edmonds East and Edmonds West Quadrangles, Snohomish and King Counties; Washington, by M. Smith, dated 1975. 4) Edmonds Landslide Hazard Map, by GeoEngineers, Inc., 1984. 19730-64th Avenue West Lynnwood, WA 98036-5904 Tel. 206-774-0106 Fax. 206-775-7506 June 1 1995 • • HWA Project No. 95084-200 The consultant's report (March 20, 1995) references document No. 1 above and relies on the subsurface investigation therein to formulate recommendations for the proposed lap pool. Documents No. 3 and 4 indicate that the subject site is within the mapped boundaries of the Meadowdale Landslide, which occurred as a result of an earthquake in 1947. Methodology The City has requested we review the consultant's methodology and evaluate whether the subsurface exploration, laboratory testing, and analysis was sufficient to adequately address slope stability concerns, drainage characteristics, erosion potential, and to provide recommendations for site development. Based on our review, it is our opinion that the subsurface investigation performed in 1990 was adequate to characterize the soil and groundwater conditions in the area of the proposed pool addition. It is our further opinion that the consultant's 1990 and 1995 investigations provided sufficient data to support appropriate analyses and prepare recommendations for site drainage, erosion control, slope stability, and general site development. l Critical Areas Ordinance Steep Slope Hazard According to the City of Edmonds Critical Areas Ordinance, a Steep Slope Hazard is any slope with an inclination of 40 percent (2.5H:1V) or greater, measured over at least 10 feet of elevation change. For such slopes, a buffer of 50 feet is required. Building setbacks from the edge of the buffer must be a minimum of 15 feet. A slope exists immediately west of 75th Place West which may meet the requirements for a steep slope hazard. The proposed swimming pool setback is 35 feet from the front property line, which is approximately 70 feet from the top of this slope. The setback is therefore within the requirements of the ordinance. It is our opinion that the recommended setback is reasonable. Landslide Hazard The Critical Areas Ordinance defines a Landslide Hazard Area by several criteria, one of which is "any area which has shown movement during the last 10,000 years." The ordinance also refers to the Edmonds Lwu& tde Hazard Map (document No. 4, above) for classification of Landslide Hazard Areas. For a site classified as a Landslide Hazard, a Critical Area Study must be prepared which shows compliance with the following two conditions: 95084-2.DOC 2 HoNG WEST & ASSOCIATES, INc. June 1 1995 0 0 HWA Project No. 95084-200 1) The proposed development will not decrease the slope stability on adjacent properties; and 2) The landslide hazard is eliminated or mitigated such that the site is "stable," as defined in City of Edmonds Ordinance 2661. For landslide hazards from deep- seated failures, which cannot be realistically eliminated or mitigated, the definition of stable is "areas classified as having a probability of earth movement of 30 percent or less within a 25-year period. The City of Edmonds has requested HWA to determine whether the referenced report meets the requirements of a Critical Area Study. As previously mentioned, the site lies within the boundaries of a relatively recent landslide and therefore is classified as a Landslide Hazard Area. In our opinion, the consultant has adequately addressed items No. 1 and 2 above. Regarding item No. 1; the consultant has clearly stated that the proposed improvements will improve slope stability by reducing loading and improving subsurface drainage. In our opinion, the consultant's recommendations for subsurface drainage 'are appropriate. In addition to groundwater drainage, the drain system should serve as an interceptor for possible pool leakage or overflow. We agree with the recommendation for a filter fabric encasing the drainage aggregate. We also agree that a geotechnical consultant should observe the pool excavation, which will allow for field changes to the drainage system, as conditions warrant (e.g. higher capacity drains if substantial groundwater is encountered). We agree with the need to control erosion at the outlet of the tightline drain. Regarding item No. 2; the Edmonds Landslide Hazard Map shows a probability of 30 percent for earth movement in the next 25 years for the subject site. The consultant's report predicts improved site stability from the proposed pool addition. Therefore, requirement No. 2 appears satisfied by the combination of the consultant's report and the Edmonds Landslide Hazard Map. Summary It is our opinion that the referenced report meets the requirements for a Critical Area Study as specified in the City of Edmonds Critical Areas Ordinance. It should be noted that the scope of services performed by HWA was limited to a site reconnaissance and review of the referenced documents. Field studies and/or verification of calculations were not performed; accordingly, we can offer no assurances regarding the performance of the site. In addition, the services performed consist of professional opinions, made in accordance with generally accepted geotechnical engineering principles and practices. 95084-2.DOC 3 HONG WEST & ASSOCIATES, INc. Junel 1995 HWA Project No. 95084-200 O.O We appreciate this opportunity to be of service. If you have any questions, or if we can be of further service, please do not hesitate to call. Sincerely, HONG WEST & ASSOCIATES, INC. VIO# EXPIRES X1 Z'L 49LJ Andre D. M' re�P.E.. Geotechnical Engineer ADM:SLH:adm 95084-2.DOC 4 HONo WEST $ AssociATEs, INC. H E M-10H I L L CONSOI NG ENGINEERS fa W 0 CO �Qo Ln U) >W F W J Z W m > 4 W Z N 0 J W 0 Z J a Q N J 0 • m W a J N N W Z N 0 0 W N Q Q � o > z C W 7 z w 0 0 m • • • Z a W 0 wF w w N 6 Z Z Z - 0 Y 0 W 3 ClCl F f~A W Q z Q W U 3 • • • W o z 0 w Q Q LL w Q 0 Z 0 m Z X Q W W Z Q Z 0 a ¢ W z F J ti N N Project No. 1636 30 July 1991 AliftzN 1991 page 1 of 3 pages . CLIENT David & Jody Spiro 19405 89th Place West Edmonds, Washington 98020 REFERENCE Property located at 15631 75th Place W, Edmonds Edmonds Permit No. SUBJECT Geotechnical inspections INTRODUCTION The purpose of this report is to present the results of geotechnical inspection conducted by Dale Hemphill of HEMPHILL CONSULTING ENGINEERS (HEMPHILL) on the proposed Spiro residence located at 15631 75th Place West, Edmonds. The geotechnical inspection was conducted at the request of David & Jody Spiro, in accordance with recommendations by HEMPHILL, and with requirements established by the City of Edmonds Building Department. The purpose of the geotechnical inspection, was to verify that the piles had been located in the required depth of resisting soils, and that the piles were properly placed. At the request of the Building Department, HEMPHILL also observed the steel in the reinforced concrete INSPECTION HEMPHILL conducted penetration tests, probing, and visual investigations within the borings for the piles, and verified that the required depths of resisting soils had been penetrated, and that the steel and concrete were properly placed. Figure 32 on the next page is a copy of Figure 32 from the geotechnical report, and as shown on the construction plans, and shows the locations and identification numbers for the piles. Figure 2 on the next page lists the installation data for the piles. 921 109TH AVENUE S. E. " • ''BELLEVUE, WA. 9B004 • 453 4760 FIGURE 32 SLOCATIONS of PILE#& 37., 36 35 34 33 32 31 30 29 NOTES: 1. PILES are NUMBERED for REFERENCE DURING CONSTF 2. SOLDIEF DIAMETI BEAMS WALL. 3. INDIVIDL ARE 18 W-10-3' BELOW 1 4. SOLDIE DIAMETI BEAMS BELOW DETERN been CC c o a 1�1 Project No. 1636 30 July 1991 page 2 of 3 pages FIGURE 2 INSTALLATION DATA for PILES PILE PILE PILE DEPTH DEPTH NO DEPTH STICK to to DESCRIPTIONS UP HARD WET ---- 1 ----- 30 ----- 0 ----- ----- ---------------------------------------- AUGER CAST 2 30 0 AUGER CAST 3 19 11 AUGER CAST 4 30 0 CLEAN OPEN HOLE 5 30 0 CLEAN OPEN HOLE 6 28 2 CLEAN OPEN HOLE 7 27 13 10 SEEPING 8 29 11 10 SEEPING 9 30 0 CLEAN OPEN HOLE 10 30 0 CLEAN OPEN HOLE 11 28 12 10 SEEPING 12 30 0 CLEAN OPEN HOLE 13 30 0 CLEAN OPEN HOLE 14 30 0 CLEAN OPEN HOLE 15 30 0 CLEAN OPEN HOLE 16 26 14 AUGER CAST 17 28 12 CLEAN OPEN HOLE 18 30 0 14 7 19 30 0 14 7 20 30 0 14 7 21 30 0 AUGER CAST 22 30 0 CLEAN OPEN HOLE 23 30 0 AUGER CAST 24 30 0 7 CAVED; FILLED TO 31; AUGER CAST 25 30 0 CLEAN OPEN HOLE 26 30 0 CLEAN OPEN HOLE 27 30 0 10 SQUEEZED IN AT 81; POURED QUICKLY 28 30 0 10 SAND TO 101; SQUEEZED IN TO 101; PUSHED LAST 4' PILE PILE PILE PILE NO DEPTH STICK SPACE DESCRIPTIONS UP ---- ----- ----- ----- -------------------------------------------- 29 11.0 9.0 Entire depth drilled into dense sand 7.5 30 11.5 8.5 of of 8.0 31 12.5 7.5 of It 8.0 32 13.0 7.0 7.5 33 13.0 7.0 6.3 34 13.0 7.0 " 6.0 35 12.5 7.5 " 6.2 36 12.0 8.0 5.5 37 10.0 10.0 HEMP HILL Project No. 1636 30 July 1991 page 3 of 3 pages Except for Pile 3, all the piles were placed to the depths as designed. Pile 3 encountered an obstruction, but because of the soil conditions, the tie to other piles, and because of the location of the pile, HEMPHILL determined that achieving the design depth was not necessary. HEMPHILL inspected reinforcing steel in the grade beams, floor slab, and foundation wall and determined that the steel was placed in accordance with the plans. CONCLUSIONS HEMPHILL concludes that the piles and grade beams, and the reinforced concrete, were placed in accordance with the plans, or with recommendations by HEMPHILL at the time of construction. Dale C. Hem hill P. E. 6"L'a Registered Engineer No. 14777 State of Washington H E M P H I LL • • • 0 W 0 N ° a 0 N � � > W F W > N J Z > Q W z N J W W U) (7 0 z J Q Q (D J 0 • • • U1 W_ 0 J N N N W Z 0 0 Cr W N Q Q � 0 4 > z w 7 z w 0 0 N • • • z o W w U O W aW N Z z ? 0 Y 0 W 0 ~ w I N w a W UO E z o o W WQ LL W Q z 0 m d a Q z X J W W 9 Q Z N Cl W Z ~ 7 J 0 N 0 H E M MPH I L L CoNsWING STREET FILE r PROJECT NO. 1636 6 March 1991 CLIENT David Spiro 19405 89th Place West Edmonds, Washington 98020 REFERENCE : Proposed Spiro house SUBJECT Response to geotechnical review INTRODUCTION ENGINEERS page 1 of 6 pages MAR 1 I 1 1*`)1 ppRMIT COUNTER The purpose of this report is to present corrections to, or clarify, the geotechnical report titled "Geotechnical Engineering for the Proposed Spiro Residence' dated 10 December 1990, by HEMPHILL CONSULTING ENGINEERS, in response to a geotechnical review by LANDAU ASSOCIATES, INCORPORATED. The geotechnical report, and the review, are in accordance with requirements by the 04y cif Edmonds for proposed construction within the Meadowdale portion of Edmonds. During a conversation with William Evans of Landau Associates, HEMPHILL became aware that some information that was either obvious to HEMPHILL because of familiarity with the project, or that HEMPHILL considered to be insignificant, was not clearly presented in the geotechnical report. Also it was determined that it would be necessary for LANDAU ASSOCIATES to have a beller understanding of some decisions that would be determined at the time of construction. Those decisions v,rould be made by HEMPHILL but it would be necessary for the City of Edmonds to require that those investigations and decisions be made by HEMPHILL in accordance with recommendations presented by HEMPHILL on the last 2 pages of the geotechnical report. HEMPHILL SUBMITTED a supplemental letter DATED 2.4 December 1990 that presented a statement of risk in accordance with City of Edmonds standards This response is presented in the numerical order of the questions and comments presented in the LANDAU review dated February 12, 1991. RESPONSE 1. Historical information is being presented by David Spiro. HEMPHILL briefly referred to the history of the site on page 9 of the geotechnical report with the statement °The largest recorded slide occurred in 1945 when large movements occurred in this gully.....'. This gully includes the site and all downhill property. Although the slide would have improved the stability of the site, along with the removal of septic systems, HEMPHILL recommended construction procedures and foundations based on the potential of instability at the site regardless of the present stability. 921 102TH AVENUE S. E. • BELLEVUE, WA. 9BOO4 • 453 4760 M PROJECT NO. 1636 6 March 1991 page 2 of 6 pages 2. The existing interceptor drain has been monitored on numerous occasions during different seasons and rainfall conditions. Flow was never observed from the portion of the interceptor drain south of the outlet pipe shown on Figure 16 on page 15. The portion of the interceptor drain north of the outlet pipe, which is located on the adjacent property to the north, has always had flow. The interceptor drains at this site were installed without any recommendations or inspections by a geotechnical engineer. HEMPHILL has concluded that the portion of the interceptor pipe on this site was placed above the sand/clay intersection. The top of the clay is lower at this site either because the site slid in the past, or because the site was a drainage channel, that then was filled with beach deposits. The top of the clay is higher on the site to the north. If the water is in fact moving on top of the clay, then the water cannot be feasibly intercepted at the present location of the interceptor pipe, or to the west. The top of the clay is more easily intercepted closer to the exposed clay at the east side of the site. Whether the groundwater is intercepted or not will not change downslope conditions since the present interceptor pipe is not functioning. If the groundwater can be intercepted easily at the time of construction then near surface conditions will be improved. If the groundwater is too deep to intercept, as it apparently is now at the location of the interceptor pipe, then intercepting the deeper water is not necessary. Figure 16 on page 15 shows the present location of the interceptor drain. Figure 51 on page 59 shows the proposed location of the new interceptor drain. The existing non functioning drain will be disconnected from the outlet pipe and abandoned. 3. The boring logs presented in the geotechnical report show that the fine sands that overly the hard clayey silt exist in a wet condition, which indicates near saturation to depths of 15 to 20 feet. The inference is that groundwater exists above the 'top of clay' as described in the geotechnical report. The groundwater blends from surface infiltration to capillary water to free groundwater. Site stability studies and the design of lateral resisting piles were based on conservative soil values, on the depths of the poor standard penetration values, wet soil conditions, and top of hard clay, resulting in a conservative line of stability of 1 vertical to 4 horizontal shown in Figure 23 on page 26. HEMPHILL assumed that everything below that line will be stable. Although the line of stability ranges from 4 to 12 feet below the existing ground surface, HEMPHILL designed piles based on the potential for all the fine sands to slide, and for the hard clay to provide lateral resistance for the piles. The piles were designed to resist 17 feet of potentially unstable soils. Since the piles are designed to resist all the soils that are wet, and since future drainage at the site will decrease surface infiltration and will possibly improve groundwater and will decrease driving soils, then downhill stability will be improved regardless of any existing groundwater conditions. HEMPHILL • a PROJECT NO. 1636 6 March 1991 page 3 of 6 pages The 30 degree dip in the recovered sample is insignificant since it is 32 feet below the line of stability and is within hard clay that had penetrometer values in excess of 10,000 psf. The statement that the contact between the Esperance Sand and the Whidbey Clay was observed at 150 feet is an error. The contact was observed south of the property at elevation 250. That contact is significantly east of the site and above a large drainage system that was installed west of 164th Street SW. 4. More accurate topographic data has been presented on a revised topographic plan. There was some confusion because of the obvious differences in the topographic plan elevations and the elevations of proposed portions of the structure and the soldier pile wall. The true conditions were obvious during preliminary site visits when designs were discussed, and the topographic differences in the plans were ignored. One location for concern was what appeared to be the south slope being supported by the frame of the structure, but the view from the west in Figure 6 on page 6 shows that the portion of the house that appears to cut into the slope in the plan view is actually the second floor, and the first floor is located 10 feet inside that location. The south slope will be excavated to create a dog run, and the cut will be supported by a low concrete wall. 5. Structural calculations have been submitted to the Edmonds Building Department and have been accepted by Whitley Jacobson Engineers. 6. The project plans have been revised to show the required pile data for construction purposes. The 30 degree dip in the recovered sample is insignificant since it is 32 feet below the line of stability and is within hard clay that had penetrometer values in excess of 10,000 psf. The cause of the dipping could be natural or a chunk that collapsed into the boring, but regardless of the reason for the sample, because of the depth below the line of stability, and the strength of the adjacent soils, the effects are insignificant and not worth extra costs to pursue. The method used to design the piles is based on the procedures presented originally by Brohms in 1968. The beam on elastic foundation method was a forerunner of the Brohms method, which began with the design of the deflection of railroad tracks by Timoshenko in the 1800's. The method used to design the lateral resisting piles includes the relative stiffness of the pile in the calculations, therefore the deflection of the shorter piles does not return to zero, as shown in Figure 37 on page 45 where the bottom of the 25.7 foot pile has a deflection of-0.217, and the bottom of the 38.8 foot pile is strained to zero deflection. A plot of the deflections shown in Figure 37 will show the deflections of the shorter piles to be nearly a straight line, while the longer piles bend significantly by comparison. The pile deflections are not independent of the soil strains. The soil and the pile must work together as a unit. Adding an extra length to the bottom of the pile changes the deflections throughout the system showing the influence of the soil beam combination. H E M P H I L L M a PROJECT NO. 1636 6 March 1991 page 4 of 6 pages Over -consolidated soils do not have a changing rate modulus, but the method uses an adjustment to change a constant rate soil to an equivalent changing rate soil. The method of applying active pressures against a pile are not appropriate because the stronger the soil the lower the active pressure, which is directly opposite to what actually happens. The stronger the soil the greater the pressure against the pile. The design of the slide forces against a pile are similar to the method of designing a rivet. Assuming that the top of the slide is not near the pile, and that the slide actually moves without hanging up (which is the worst condition that can occur), then the stronger the soils the greater the drag on the pile. If the proper soil parameters (cohesion and friction) are used, then the stronger the soil the greater the drag around the pile. If active pressures are used then the stronger the soil the lower the pressures against the pile. The calculations shown in Figure 37 on page 45 show the deflections, bending moments, and shear for various depths of placement of the same pile. HEMPHILL usually places piles at depths into over -consolidated soils at least the depth of potential slide soils, depending on the relative strengths of the driving and resisting soils. The recommended depths of piles are described in Figure 32 on page 40; therefore the shorter piles will not be used. The final depths will be determined at the time of construction as the true conditions are revealed for each pile. 7. The soldier pile wall is designed to support a horizontal compacted backfill and some minor slough debris. The hard Whidbey Clay will not apply pressure against the wall as a cohesionless soil would, therefore the potential for a slope failure is not considered in the design, and the slope of the Whidbey Clay is ignored in determining the lateral forces on the wall. The transitions for the ends of the wall have been included in the revised drawings. The statement that the spacings will be determined after the excavations have been completed is in error. The statement should read that the spacings will be determined after the proposed depth of excavations have been determined, or if the wall is moved into or away from the slope at the time of construction because of conditions, then the height of the wall will change, which will also change the spans, as shown in Figure 44 on page 50. 8. After careful review of the areas to be excavated, we have determined that the amount to be excavated for the construction of this project are accurate. The detention system is considered a utility and therefore not included in the calculations in accordance with Edmonds building code. The grade beams will be placed at or near grade, requiring little or no excavation. The total excavating will not exceed 500 yards. 9. The placement of fill along the west side of the site will be much less than the volume to be excavated and will have no detrimental effect on the stability of the site, especially considering the other improvements that increase the site stability far more than any decrease from the fill. H E M P H I LL F-1 w PROJECT NO. 1636 6 March 1991 page 5 of 6 pages To resist lateral loads the piles are far overdesigned for vertical support and are capable of supporting loads of 80,000 pounds using conservative values of 6000 psf end bearing and 1000 psf side friction within the Whidbey Clay. Assuming a heavy equivalent pressure of 50 pcf and a high friction factor of 0.5, the greatest downward drag on the piles would be 13,000 pounds. That assumes full mobilization along the entire length of the upper sandy soils. 10. The drawings have been changed to show the rockery in accordance with recommendations by HEMPHILL. The standard detail by the City of Edmonds will allow a rockery to be build that will fail if build to the worst allowable conditions rocks are cubic shaped. 11. Slides in Whidbey Clay and Lawton Clay are generally the result of shallow surface slides which result from the weakening of the upper 2 to 3 feet of soils due to weathering (wetting and drying, freezing and thawing, root action, direct rainfall). The debris slide is generally local and does not include a large area. The more dangerous slides are flow slides resulting from complete saturation of loose soils. There is no evidence that flow slides have ever occurred in the vicinity of the site. Any loose soils observed at the base of the slopes in the general vicinity are the result of 'slope wash' which generally occurs in small quantities at a time. The potential for a larger surface slide is remote, and there is a buffer zone that will protect the house if such a slide should occur. 12. Most of the east slope that will be within 20 feet of the proposed soldier pile wall is less than 30 degrees. There was no mention in the geotechnical report of an angle of repose for the east slope. The undisturbed Whidbey Clay can stand vertically for many feet, and the slough debris can stand at angles of 1 V : 1.5H if protected by vegetation. The south portion of the existing slope is fairly stable at the bottom because it is approximately the angle of repose of the slough debris. If debris should slide over the soldier pile wall it will lie between the wall and the house. There is not requirement that the debris be removed, but the owner should be aware that there is the remote potential for debris. 13. Typical drainage plans have been added to the design drawings, but final decisions for drainage should be determined at the time of construction, and the contractor should be aware that the drainage shown on the drawings are not final. 14. Agreed! 15. A. The dates used by HEMPHILL were stamped on photographs of the large very damaging slide in the general area. HEMPHILL • 0 PROJECT NO. 1636 6 March 1991 page 6 of 6 pages B. There is no such thing as a specific blow count versus consistency. The standard penetration test (SPT) can be very misleading if not used with judgment, provided that it is accurate. If a fairly undisturbed sample is recovered, then a visual examination is more accurate that the SPT. The SPT varies with grain size, plasticity, and water content. Other factors are height of hammer, condition of spoon, side friction, pounding on chunks of rock or gravel, slumping of the hole and pounding into the debris, missed blow counts during mental lapses, you name it, I've seen it. The consistencies recorded on the boring logs were based on visual examinations of the recovered samples. The boring logs also show the results of penetration tests conducted on the samples. C. Figure 29 is a standard figure used by HEMPHILL and the 90% was inadvertently included. The intent, regardless of any given compaction, is that the grade beam should not settle enough during the curing process to be damaged or to make the placement of the upper structure difficult. After curing the condition of the soils is insignificant. D. True! Those values are for light loads from deck and stair footings. The report also includes other important design recommendations for methods to attach decks to prevent damaging the main structure during settlement, and also includes criteria which will allow those footings to be jacked back into place in case of settlement. CONCLUSIONS Except for some disagreement of design criteria for the piles, and some clarifications of poor or misleading descriptions or drawings in the report and project plans, HEMPHILL agrees that most of the comments by LANDAU ASSOCIATES were appropriate, and the responses in this report attempt to clarify the geotechnical report and project plans, or to present any omissions. Dal C. Hemphill P. E. ED-0 Registered Engineer No. 14777 State of Washington HEAfp; A e• w Na�AL,,��N�\�4. HEMPHILL E §',MEET F)LE CITY CLERK CIVIC CENTER EDMONDS. WA 98020 COVENANT TO NOTIFY The undersigned property owner(s), as applicant for a building permit/grading permit, in consideration of the mutual benefits to be derived, in part -due to the review of my application, do hereby stipulate and promise to the City of Edmonds, Washington, a noncharter optional municipal code city, as follows: 1. SUBJECT TRACT: The undersigned is/are the owner(s) of certain real estate located in the City of Edmonds, Snohomish County, Washington, and further described as follows: IYle Aou)hd<. &4e 11 JL't Iemenf-af ela' BUL bbb D-03 N (00 1 L 0'1 1nt- 2S E. 3W 73 I,#azin�=d (Q,aa.,� Tt e VU ID bt b fJDA L2 -dY Kd ae� 4:C2 rem. 2� 54338 2. STATEMENT OF HAZARD: The above described subject tract or some portion thereof lies within an area of potential earth subsidence or landslide hazard. The risks associated with development of the site have been assessed and determined by professionals in the employ of the undersigned property owner(s) through written reports required by, and on file with, the City of Edmonds, Building Division, in application file number 2 1;2 ;2 All prospective inhabitants, buyers, lenders, or other persons acquiring any interest in the subject tract are hereby notified of such potential hazards and of the information on file with the City, incorporated by this reference as CIVIC CENTER ONDS. WA 99020 fully as if herein set forth. In addition to an assessment of any such hazard, said City files may contain conditions or prohibitions on development imposed by the City in the course of permit issuance and may reference any features in the design which will require ongoing maintenance or future modification to address anticipated soil changes or movement. All such prospective inhabitants, buyers, lenders or other interested parties are encouraged to review said files and shall be charged with notice of the contents thereof. 3. PROMISE TO NOTIFY: The owners, on behalf of themselves, their heirs, agents, successors in interest and/or assigns do hereby promise to inform any successors and assigns that said described property lies within a potential earth subsidence and landslide hazard, of any risk identified by reports of the professionals and associated with the development of that property, and of any conditions, prohibitions, restrictions, or ongoing maintenance responsibilities which exist with respect to development of that site. 4. DEVELOPMENT APPLICATION: These statements are made in and with regard to an application for a_ issued this day of A%9 19_, under City of Edmonds file No. q/ 0,53e) 5. WAIVER: I/We/the corporation as the owner of the described tract, and on behalf of my/our/ heirs, successors and assigns do hereby waive the right to assert any loss or claim against the City of Edmonds, its agents, employees, or independent contractors, which may arise by reason of or out of the review of our application and/or issuance of the above -described permit for development approval by the City for the subject property, or from the construction of any building 1 41 1' OCITY CLERK CIVIC CENTER EDMONDS, WA 98020 • or structure or any grading, filling or other action pursuant to said permit, excepting, however, any loss arising from the sole negligence of the City, its officers, employees, or independent contractors. DATED this _5 day of U-t"- vkb j.A 19,10 11n Q ICJ l�l,�-D (I ividual) By (Individual) (President) By (Secretary) VOL. CITY CLERKO _ CIVIC CENTER EDMONDS. WA qE G020 INDIVIDUAL ACKNOWLEDGEMENT STATE OF WASHINGTON SS. COUNTY OF *fftG On this day personally appeared before me J9AIW6 S/D�p� AM I)AUM S0i�Nb to me known to be the individual.5 described in and who executed the within and foregoing instrument, and acknowledged that T &jl signed the same as free and voluntary act and deed for the us s and purposes therei 't"io,ed. GIVEN under my hand and official seal this S-a_ day of CD iqqo CD 4 STATE OF WASHIN COUNTY OF KING - - - •D• at CORPORATE ACKNOWLEDGEMENT ss. On this day of , 19 , before me, the undersigned, a Notary Public in and for the State of Washington, duly commissioned and sworn, personally appeared and to me known to be the President and Secretary, respectively, of the corporation that executed the foregoing instrument, and_ acknowledged the said instrument to be the free and voluntary act and deed of said corporation, for the uses and purposes therein mentioned, and on oath stated that they were authorized to execute said instrument and that the seal affixed is the official seal of said corporation. WITNESS my hand and official seal hereto affixed the day and year first above written. ki p NOTARY PUBLIC in and for the State of Washington, residing at ui.. 24 42phn a CITY CLERK _ CIVIC CENTER EDMONDs. WA 98020 ILE F�Ef Fill INDEMNITY AND HOLD HARMLESS AGREEMENT The undersigned applicant(s) for building permit, subdivision, planned residential development, in consideration of the mutual benefits to be derived, in part due to the review of my/our application by the City of Edmonds, Washington, a noncharter, optional municipal code city, do hereby indemnify, waive, release, and stipulate as follows: 1. I/We do state that we have been provided with/have waived receipt of a copy of an earth subsidence and landslide hazard map made available to me by the City showing those hazards previously identified by the City through its consultant Roger Lowe and Associates, Inc. and a follow-up report by GeoEngineers, Inc., and state that I/we have reviewed or are fully aware of the contents and existence of said maps and of reports explaining said maps and identifying certain hazards to be anticipated or encountered in the construction or development upon my property. I/We am aware that copies of said report are on file with the City Clerk and available for my review at my request. In addition, I/we have undertaken an independent assessment of the hazards through professional consultants of my/our choosing. 2. PROMISE TO INDEMNIFY: I/We do promise to release and indemnify the City, its agents, officers, employees, and/or independent contractors from any and all claims, damage or loss of any kind or nature resulting from or to any party or person, or the property thereof as a result of: vat. 2 4 6 3 PAGE 2 418 A. The construction design, soils report, and/or any other act required as a part of the building permit application process, subdivision process or planned residential development process and the subsequent preparation of my land for and construction thereon v n t __ l--w-r-i-� CITY LERK civic NTER EDMONDS. WA 08020 of any structure or building by myself/ourselves, or my/our agents, employees or contractors and/or the construction of any building or structure. B. The provisions of false, inaccurate, or misleading information by myself/ourselves, or by my/our agents, employees or contractors in the permit, subdivision, or planned residential development process; and C. Any risk or hazard of which I have been notified or could reasonably have had notice of by review of the documents on file with the the City of Edmonds or its building division or could have discovered through reasonable professional efforts of my/our experts. 3. The undersigned applicants hereby waive and release the City from any and all claims arising from the situations described in this agreement, but specifically reserve claims against the City, its officers, employees, or independent contractors, from any loss or damage which arises from or out of the City's sole negligence. Nothing herein shall be construed to be a promise to indemnify the City, its officers, employees, or independent contractors, from any loss or damage caused by their sole negligence. DATED this S day of A- V-C2 h-q-,A 19 q(> and given with reference to building permit application, subdivision application, planned residential development. application no. 6�/033q READ CAREFULLY - CONTAINS WAIVER AND INDEMNITY PROVISIONS 7 ck/r . h I ' ividual '0 (: By President By Un, 9 n 6 3 pnE2419 (Secretary) tkitf-0 -A" 1tC .`�'. CITY CLERK 1 _ CIVIC CENTER EDMONDS. WA 98020 INDIVIDUAL ACKNOWLEDGEMENT STATE OF WASHINGTON ) ss. COUNTY OF -KTITG ) Gwyn / On this day personally appeared before me FDA NAIL Sto_ t)Lb -S to me known to be the individual des i ed in and who executed the within and foregoing instrument, and acknowledged that: signed the same as�S" ifree and voluntary act and deed for the us s and purposes therei tinned. GIVEN under my hand and official seal this k,<-N_.,d`ay of -.,A PUBLIC in and forata1�C% n, res din t of Wash' 9 ` CORPORATE ACKNOWLEDGEMENT STATE OF WASHINGTON ) ss. COUNTY OF KING ) On this day of 19 , before me, the undersigned, a Notary Public i.n and for the State of Washington, duly commissioned and sworn, p&-sonally appeared and , to me known to be the President and Secretary, respectively, of the corporation that executed the foregoing instrument, and acknowledged the said instrument to be the free and voluntary act .and deed of said corporation, for the uses and purposes therein mentioned, and on oath stated that they were authorized to execute said instrument and that the seal affixed is the official seal of said corporation. r~ ` WIT ESS my hand and official seal hereto affixed the day and C-71 year first Dove written. ra; NOTARY PUBLIC in and for the State of Washington, residing :r a at Yr � n' VOL.2463PAGE2420 417 4 Legal: David & JoaSpiro EXHIBIT A M Meadowdale Beach Supp. Plat, Blk 000 D-03, N 100 ft of Lot 25 Less E 380.73 ft and less W 10 ft to City of Edmonds for Road per Quit Claim Deed Rec Af No 2254338 ••1J ni VOL.2463P&GE2421 CITY CL E CIVIC CENUq 6t�Morvfls, WA 08020 STRI a 0060.090.014 FrZMI JEH/crd 10/19/88 RE:10/26/88 RE:10/31/88 CITY OF EDMONDS, WASHINGTON �-' COVENANT TO PARTICIPATE IN/WAIVE RIGHT TO PROTEST LID WHEREAS, the undersigned owners are the owners of certain real property located in Snohomish County, Washington, which is legally described on Exhibit A attached hereto and incorporated herein by this reference as if set forth in full, hereinafter referred to as "the property," and WHEREAS, the owners have applied to develop the property aTrec i dPnrn (insert development type), which will have an impact on (insert impact), (e.g., storm drainage, streets, water, sewer), and WHEREAS, as a condition of approval of the proposed development,* the City has required the owners to mitigate impacts of the development and the owners and the City have agreed that such mitigation may take the form of participation in a local improvement district (LID) for construction of certain improvements deemed. necessary to mitigate the impact,. now, therefore, FOR AND IN CONSIDERATION OF the City's approval of owners' development of the property described on Exhibit A without requiring owners to presently construct the improvements hereinafter described, the owners covenant and agree as follows: 1. Warranty of Title. The owners warrant that they are the owners of the property described on Exhibit A and are authorized to enter into this Agreement. 2. Acknowledgment of City Authority. Owners acknowledge that State law and City ordinance provide that the City may require that the following improvements be designed and constructed as a condition of, and to mitigate the effects of, the development proposed by the owners (insert description of specific improvements): construct curb and sidewalk alon the we.te ll portion o 0 �wners urfi�r ac�cnowle gb tthat the consideration for this Agreement is approval of owners' development by the City without requiring that such improvements be completed prior to such approval. 3. Acknowledgment of Special Benefit. Ownerl�cknoadge� ►4�-,� - �� 0 —1— voL 2463Pn6i2422 Ti-R(ll l 1 C;A �,_ ITY CLERK CIVIC CENTER EDMONDS. WA 98020 that the entire property legally described on Exhibit A, and if the proposed development is a subdivision or short subdivision, each and every lot to be created as part of the development of the property legally described on Exhibit A, would be specially benefitted by the construction of the improvements specified in paragraph 2 above. 4. Agreement to Participate in or Waive Protest of LID. A. Petition Method. Owners understand that the formation of a local improvement district which includes the property described on Exhibit A for the purpose of providing the specified improvements will result in the property being assessed a proportionate share of the costs of those improvements. With full understanding of this consequence, owners agree to sign a petition for the formation of an LID or ULID for the specified improvements at such time as a petition is circulated or the City requests the owners to sign such a petition and the owners hereby agree that the Mayor of the City may sign the petition for the owners as the owners' attorney in fact, should the owners fail, refuse or be unable to do so. B. Resolution Method - Waiver of Right to Protest. Owners understand that owners have the right to protest formation of an LID or ULID to construct the specified improvements pursuant to RCW 35.43.180. With full understanding of owners' right to protest and the consequences of formation of an LID or ULID, owners agree to participate in any LID or ULID to design or construct the specified improvements and to waive the right to protest formation of the same. Owners shall retain the right to contest the method of calculating any assessment under such LID or ULID and the amount thereof, and shall further retain the right to appeal confirmation of the final assessment roll in the manner provided by law. 5. Binding Effect - Duration. This Agreement shall be recorded with the Snohomish County Auditor, shall constitute a covenant running with the land described on Exhibit A, and shall be binding upon the owners, their heirs, successors in interest and assigns, provided, that this Agreement shall be valid only for a period of ten (10) years from the date it is signed by the owners, after which it shall expire and become null and void. 6. Specific Enforcement. In addition to any other remedy provided by law or this Agreement, the terms of this Agreement may be specifically enforced by the City of Edmonds. torney's Fees. In any suit or action brought by the )20 YOL.2463phG[2422 JEHO1115A Ve . '. CITY CLERK • CIVIC CENTER EDMONDS. WA 98020 City of Edmonds to enforce any provision of this Agreement or to redress any breach, the owners covenant that the City shall be entitled to reasonable attorney's fees and costs in addition to any other remedy. DATED this day of19� �0 M OWNERS 0 >.. STATE OF WASHINGTON %,� )ss: COUNTY OF ) I certify that I know or have satisfactory evidence that signed this instrument and acknowledged it d be (his/her) free and voluntary act for the purposes mentioned in this instrument. DATED this � 1day of 19a� NOTARY PUBLIC My commission expires: STATE OF WASHINGT N ) )ss: COUNTY OFF ) I certify that I that know or have satisfactory evidence signed this instrument, on oath stated that (he/she) was authorized to execute the instrument and acknowledged it as the (title) of instrument was executed) (name of party on behalf of whom to be the free and voluntary VOL. 2463PASE2424 -3- JEHO1115A -R , 7 -�, 9 N�-Rnrsiir Me. - . regal : David & Ake Spiro EXHIBIT A • Meadowdale Beach Supp. Plat, Blk 000 D-03, N 100 ft of Lot 25 Less E 380.73 ft and less W 10 ft to City of Edmonds for Road per Quit Claim Deed Rec Af No 2254338 116 (13 vo[. 2463PA6E2425 97 0 7 2 2 0, 0 1. ifi STET FILE t . n ts•-.It- - 4 QUITCLAIM DEED 01. and Dolaiar. M. carpi ll► the amiddwsuoa .f .................. auttlal, comalderatlm ....... . Una ,best" d wtiMe to horsey adinowledp4 and abe of bownts to smarm by reason of gating aw sad mstabiWAC a pub- row tardliglt ......their ............. peope,ty. and which to h-reottsr d....tb.d. do . cover. tows aM gWt•dWm to the City ofvdtnonds, step at Washington, fo► the use Of the pulille forece►. as a public road Said Mfberwg. So fellootng described real elute. Including any Wassail therein Which senator may hereafter acquies, vta: The vast.10 feet of the following described propertyi V. 200.07 ft. of Tracts 29 and 26. Supplemental Plat of Meadoerdale Beach. Ldmonds. Vaahington NO SALES TA R E Q V I R =7 'JUL 18 1:1 ,: STREET FILE "bat" in the Catety of annhemirl, state of Wamhtngtna l Ttr Omni— Hereby agree and comment to the •tabliahm.nt of Mid road as .urv,yod and of record in the My at mdtnu de Oig —Wo office as survey Ire end to the perpetual tnatntansnre or the -"is sm a City :t,eal, and wat,* W crabs for domm"m of erhalever kind wabra may be of—lonod to adjacent tmn.l by the location. andMlrnmdf. oowdrtietla► dratnagm sad maintenance of mod street, and asr..a end evnerhta to the tent of the City to me" all "cannery dopes tar auto and tone Monaca, they extend beyond the right -of way line, upon ab..r. mentumed tttfwet. as in omdwwty With aimed" p,set*M of city etrmet a•wteuetion, and to the aami Went and purpwa as it W rfgbbs Wig paYM W Mod agWred b eeadendatba proceedings abler [silent Domain dtalut.e of W state Gad saasaawfd Ms A wfq the had Send be bamd" Mea IM theater .asaeesswa err aedgaa Oedsg Lade ......... Z.Z. ty of ... fu d1►i'. HF��.yv✓i� . .5.13:99 si ► _53 1► _ IAl RECORDS ITATE Or WAAHINOT010. COUNry or . .............. Oa. ......... .. ..... ... .. .... 4w ad ...... . .... ....... .... ... . ..... Is won WA the a Notary Public to and for the @tat* of Wasidngton, duly sommiselowid and awora personally cum .............. ... . ... ..... ..... ............... . ..... . ....... ........... ... I* as lum to be the. ad me — the Cwpw*Vm that executed the within and I'mo. ng InstrumeriL WW 8011MIGOVISked the said loalftmost to be the tree and Voluntary Oct and do" of mid Corporation for the noes and popesthwain mentioned and on oath stated that --ho- "Lbwtftd to execute said Instruln" t. and that 00 seal affixed Is the "al of sold Cbrporaum IN WrrNMU WHER20r. 1 have hereunto met my hand and affixed my *mJ the day mid year in this eartAftate 866" written. NO" P"blW Is and 04W the 911014 Of WOOMMAMOIL raet"lag at WfATN OF WABMNG"N. coulm or A k'sk ...... . ............... on 1611116 ftb... .. and 'TrAl 01" la.73-. batore Moa . pletary ruhile to day of I Mat as mat* 41 Wasbingtok dull smanklaska" a" swam personally came _..At.S. -b.. _. -4f# nt &a L ie me 1110sani to be the hkmvw"L . devertbod to had %Mbo go""" the within tootrament and adkowas"god to me that fts" and "wed tree a" vattrtdy "t and 6"d for the sass a" purpooss thereto mentioned. my. band and seal the day and yew Mat &be" wvUW- 0T4 to 's --J�4.pry pubild to am for the stale of WUNRCION. P656&nl a IOF OFFICIAL RECORDS on 0MCIAL AtCORM VOL 6H. too lffl�WWMWWWWp City of Edmonds IRRIGATION / LAWN SPRINKLER PERMIT 0�� . ^ C WING O a � � CK%OW YREVf_NT� ONASSEMBl� LOCATIONS� ON TO {VATER SYSTEM C1AR 2 7 19,5 PEMMIT COUNTER APPLICANT: SERVICE ADDRESS: J b �r �— PHONE: MAILING ADDRESS: CONTRACTOR: C'l,Ayn-1=1—?0 d a r-- �lhl �{ PHONE: MAILING ADDRESS: Zoo 3 �`� W �Z, l\� IF — PURPOSE: WATER QUALITY! To insure potentially contaminated water cannot re-enter the drinking water system. at your property or through the City's supply system. NOTE: ALL IRRIGATION/SPRINKLER SYSTEMS CONNECTED TO THE CITY OF EDMONDS WATER SUPPLY MUST HAVE A PROPERLY INSTALLED APPROVED BACKFLOW PREVENTION ASSEMBLY(S). TESTS REQUIRED BY A PRIVATE TESTER AT THE OWNER'S EXPENSE ON 3 OF THE 4 ASSEMBLIES AVAILABLE. AT THE TIME OF INSTALLATION AND ANNUALLY THERAFTER, ALL RESULTS SHALL BE FORWARDED TO THE EDMONDS WATER SECTION LOCATED AT 7110 - 210TH ST SW, EDMONDS, WA 98026. FAILURE TO COMPLY WITH THIS WILL RESULT IN TERMINATION OF WATER SERVICE TO THE PREMISES. INSPECTION DATE TEST RECV•D DATE Atmospheric Vacuum Breaker(s) No Ten Pxquimd Double Check Valve Assembly Pressure Vacuum Breaker Reduced pressure principal assembly (used only with fertilizer injection) CITY OF EDMONDS FOR INFORMATION OR INSPECTION CALL 771-0235 EXTEIVSIOIN 644WIIV--649 nwa ��av�cr_�i �tn.0 t,�v r,v DATE APPLIED t' %' 4TS— ^,ttor revie'RERMITeFEE ha^" ^,i�zar. � , PLAN APPROVED BY �. r approvecLeCE1PT`#n the ;% !c,;1c vv i s;ste :ir't ctior is provraed: DATEISSUED j DATE FINAL APPROVAL PERMYr EXPMES 90 DAYS AFTER DATE OF ISSU CE ASSEMBLY . EXCELDATAdWATERIMUGATI W'&ter Department Lie 1nC.189v CITY OF EDMONDS BARBARA MAHEY MAYOR 121 5TH AVENUE NORTH • EDMONDS, WA 98020 • (425) 771-0220 FAX (425) 771;0221 DEVELOPMENT SERVICES DEPARTMENT Planning • Building • Engineering April 9, 1999 Dr. & Mrs. Spiro 15631 75th Place West Edmonds, Washington 98026 RE: Homeowner Insurance Coverage for Meadowdale Development As you may recall, development of your home was subject to Edmonds Community Development Code (ECDC) Chapter 19.05.050 which regulated construction and insurance coverage requirements for all designated Meadowdale Landslide Hazard Area development. The purpose of this letter is to inform you that the Edmonds City Council has enacted a change which effects your homeowners policy that was required by this ordinance. If you recall you were required to post a one million dollar homeowner policy in order for your home to be granted final occupancy. Please be advised, the City Council has repealed this requirement effective April 16, 1999. In lieu of this policy the City Council will be holding future public hearings to determine alternate coverage methods to ensure that the intent of ECDC 19.05.050 are still met. Please contact the City Clerk if you are interested in attending these meetings. You may wish to consult your insurance professional to determine the proper amount of insurance coverage necessary to meet your specific needs. Since the insurance requirement is repealed the City no longer requires to be informed of your coverage or be provided with a copy of your current policy. Please feel free to contact me if you have any questions at 771-0220. Thank you, $40t�k� Jeannine L. Graf Building Official • Incorporated August 11, 1890 • Sister City - Hekinan, Japan ri 11 is lhc.189v CITY OF EDMONDS 250 5TH AVENUE NORTH - EDMONDS, WA 98020 - (206) 771-0220 - FAX (206) 771-0221 COMMUNITY SERVICES DEPARTMENT Public Works . Planning • Parks and Recreation • Engineering June 13, 1997 David A & Joanne Spiro . 15631 75th Place West Edmonds, Washington 98026 Re: Home Owners Insurance Policy BARBARA FAHEY MAYOR As you may recall, the Meadowdale Earth Subsidence Landslide Area Ordinance requires homeowners to post and maintain a policy of general public liability insurance. This insurance is required for a period of not more than 10 years from the date of final approval (occupancy was granted on 11/31/91). According to City records, your certificate of insurance expired on 4/30/92. At your earliest convenience please inform your insurance company that a current copy be provided to the City. As a reminder, the policy must be for general public liability insurance naming the City as additional named insured against personal injury, death, property damage and/or loss arising from, or out of, the City's involvement in the permitting process for the project in the amount of one million dollars. The policy shall also.state that the City will be notified 30 days in advance of policy cancellation. Note, this requirement of insurance is transferable to any and all owners within the 10 year period. If you have recently sold your property, please notify the City in writing of the name of the new owners., Please contact me at 771-0220 if you have any questions regarding this insurance . requirement. Thank you, Lara Knaak - Permit Coordinator cc: State Farm Insurance. Company Building Official ® Incorporated August 11, 1890 0 , Sister Cities International — Hekinan, Japan CITY • EDMONDS • 250 - OTH AVE. N. - EDMONDS, WA Y9020 - (206) 771-0220 - PAX (200) 771-0221 COMMUNITY SHRVICES DEPARTMENT Publlo Works • Planning • Parks and Recreation • Engineering /�'tca,o Tom: Q.f.(� C.�..,.�..�a-✓ o 'tee ,� / LAURA M. HALL r, 0. '05sx **I- S6 /'��o�so%"''� �►,6.�.✓iGe� �ic- G/r..o,✓ .rauf a ��' � uis�- ��e�fw•.tr'c /!tip .e✓1h <� u iie �>� •L�c. !�✓/-s'7�iai✓o/��i1� � f�- �.�/°' �„i6 ✓e�✓f �iis c�G.w✓ mw >� w� <i .6.� .rya � o.✓ .•s ��''9+ rtt file- • lncorpo rated August 21, 2990 s Sister Cites Intarnational. — Hek)nan. Japan TRANSMISSION.REPORT THIS DOCUMENT (REDUCED SAMPLE ABOVE) WAS SENT ** COUNT # 1 *** SEND *** NO REMOTE STATION I.D. START TIME DURATION #PAGES COMMENT 1 93612731 8-25-95 8:25AM 1 0'59" 1 TOTAL 0:00'59" 1 XEROX TELECOPIER 7020 r 8 9 0- 1 9C� 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 Inema Tv: Ale- 6,4n,e.-fa/ *Ifrle j xoo is 14 = �u�usr 24 ��ps LAURA M. HALL MAYOR FOx h, 3(a /-?r 3/ . /f Ne, ej %� ✓/ ,coo,,.. wI�'�"'`���/�, % f�.�,o 4;-v -jo0vwr zpP4 cv-+ 4-19) • Incorporated August 11, 1890 • Sister Cities International — Hekinan, Japan MEMORANDUM18 1995 Date: July 18, 1995 To: Planning Division From: Ron Holland V" 6-frf Water/Sewer Supervisor Subject: Pool Drain at 15631- 75th Place West (1511901 I spoke with Ralph Simonds with Master Pools about the draining of the pool at 15631 - 75th Place West. It has been clarified by him that the drainage area around this pool will go to the storm drain, and the pool waste will be tied directly to the sanitary sewer via an air gap to insure no direct connection to the pool from the sewage. RH/lk cc: Ralph Simonds Master Pools 20031 Ballinger Road NE Seattle, WA 98155 wordata\water\ 15 63 1 poo ®fin/-f-:� "zre- 0-0 City of Edmonds cza Public Works • • MEMORANDUM �f 4-1 Date: March 29, 1995 To: Planning Department From: Ron Holland 0144 Subject: POOL DRAINS TO STORM LINE - OPEN DITCH AT 15631 - 75TH PLACE WEST Please note that all pool drains are to be tightlined. to sanitary sewer. I have noticed that the proposal provided drain to the storm drain. This must be corrected before any pool is allowed to be installed. RH wordatalwateiXspiro City of Edmonds (Q Public Works 890-194 June 6, 1995 CITY OF EDMONDS 250 - 5TH AVE. N.: EDMONDS. WA 98020 • 12061771-0220 • FAX (206) 771-0221 COMMUNITY SERVICES DEPARTMENT Public Works • Planning • Parks and Recreation . Engineering David Spiro 15631 75th Pl. West Edmonds, WA 98026 Re: Critical Area study for swimming pool Dear Mr. Spiro: LAURA M. HALL MAYOR g ETPFRLE We have received the critical area study peer review for your swimming pool from Hong West Associates, Inc. After reviewing their analysis and other data in our files we have determined that the study satisfies the requirements of the Critical Area Study. I have spoken to the Building Division regarding the status of your permit. They are still in the process of reviewing the recent data provided by Hong West and other information. When they have completed their review they will contact you. If you have any questions regarding the status of your permit please contact the City Building Official, Jeannine Graf. Sincerely, V Kirk J. Vinish Project Planner . 0 Incorporated August 11, 1890 e Sister Cities International — Hekinan, Japan C'1100010- VI RECEIVE JUW p 2 r3n U01 fIONG WEST & ASSOCIATES, INC. June 1, 1995 Geotechnical Engineering HWA Project No. 95084-200 Hydrogeology J Geoenvironmental Services Testing & Inspection City of Edmonds 250 5th Avenue North Edmonds, Washington 98020 Attention: Mr. Kirk Vinish Subject: CRTTICAL AREA STUDY - PEER REVIEW Spiro Residence Pool Addition 15631 75th Place West Edmonds, Washington Reference: Proposed Lap Pool, Geotechnical Engineering, by Hemphill Consulting Engineers, dated March 20, 1995. Dear Mr. Vinish: In accordance with your request, Hong West & Associates, Inc. (HWA) has completed a geotechnical peer review associated with the proposed new swimming pool construction at 15631 75th Place West in Edmonds, Washington. As part of this study, we visited the site and reviewed the consultant's methodology, conclusions, and recommendations as summarized in the report referenced above. Particular emphasis was placed on recommendations relating to the City of Edmonds Critical Areas Ordinance (Ord. No. 2874, rev. No. 3014). In addition to the referenced report, we reviewed the following documents: 1) Geotechnical Engineering for the Proposed Spiro Residence, to be Located at 15631 751h Place West, by Hemphill Consulting Engineers, dated December 10, 1990. 2) Addendum to Geotechnical Report, Proposed House, Located at 15631 75th Place West, Meadowdale, by Hemphill Consulting Engineers, dated December 24, 1990. 3) Preliminary Surficial Geologic Map of the Edmonds East and Edmonds West Quadrangles, Snohomish and King Counties, Washington, by M. Smith, dated 1975. 4) Edmonds Landslide Hazard Map, by GeoEngineers, Inc., 1984. 19730-64th Avenue West Lynnwood, WA 98036-5904 Tel. 206-774-0106 Fax. 206-775-7506 i June 1, 1995 i HWA Project No. 95084-200 The consultant's report (March 20, 1995) references document No. 1 above and relies on the subsurface investigation therein to formulate recommendations for the proposed lap pool. Documents No. 3. and 4 indicate that the subject site is within the mapped boundaries of the Meadowdale Landslide, which occurred as a result of an earthquake in 1947. Methodology The City has requested we review the consultant's methodology and evaluate whether the subsurface exploration, laboratory testing, and analysis was sufficient to adequately address slope stability concerns, drainage characteristics, erosion potential, and to provide recommendations for site development. - Based on our review, it is our opinion that the subsurface investigation performed in 1990 was adequate to characterize the soil and groundwater conditions in the area of the proposed pool addition. It is our further opinion that the consultant's 1990 and 1995 investigations provided sufficient data to support appropriate analyses and prepare recommendations for site drainage, erosion control, slope stability, and general site development. Critical Areas Ordinance Steep Slope Hazard According to the City of Edmonds Critical Areas Ordinance, a Steep Slope Hazard is any slope with an inclination of 40 percent (2.5H:1V) or greater, measured over at least 10 feet of elevation change. For such slopes, a buffer of 50 feet is required. Building setbacks from the edge of the buffer must be a minimum of 15 feet. A slope exists immediately west of 75th Place West which may meet the requirements for a steep slope hazard. The proposed swimming pool setback is 35 feet from the front property line, which is approximately 70 feet from the top of this slope. The setback is therefore within the requirements of the ordinance. It is our opinion that the recommended setback is reasonable. Landslide Hazard The Critical Areas Ordinance defines a Landslide Hazard Area by several criteria, one of which is "any area which has shown movement during the last 10,000 years." The ordinance also refers to the Edmonds Landslide Hazard Map (document No. 4, above) for classification of Landslide Hazard Areas. For a site classified as a Landslide Hazard, a Critical Area Study must be prepared which shows compliance with the following two conditions: 95084-2.DOC 2 HONG WEST & ASSOCIATES, INc. June 1, 1995 0 HWA Project No. 95084-200 • 1) The proposed development will not decrease the slope stability on adjacent properties; and 2) The landslide hazard is eliminated or mitigated such that the site is "stable," as defined in City of Edmonds Ordinance 2661. For landslide hazards from deep- seated failures, which cannot be realistically eliminated or mitigated, the definition of stable is "areas classified as having a probability of earth movement of 30 percent or less within a 25-year period. The City of Edmonds has requested HWA to determine whether the referenced report meets. the requirements of a Critical Area Study. As previously mentioned, the site lies within the boundaries of a relatively recent landslide and therefore is classified as a. Landslide Hazard Area. In our opinion, the consultant has adequately addressed items No. 1 and 2 above. Regarding item No. 1; the consultant has clearly stated that the proposed improvements will improve slope stability by reducing loading and improving subsurface drainage. In our opinion, the consultant's recommendations for subsurface drainage are appropriate. In addition to groundwater drainage, the drain system should serve as an interceptor for possible pool leakage or overflow. We agree with the recommendation for a filter fabric encasing the drainage aggregate. We also agree that a geotechnical consultant should observe the pool excavation, which will allow for field changes to the drainage system, as conditions warrant (e.g. higher capacity drains if substantial groundwater is encountered). We agree with the need to control erosion at the outlet of the tightline drain. Regarding item No. 2; the Edmonds Landslide Hazard Map shows a probability of 30 percent for earth movement in the next 25 years for the subject site. The consultant's report predicts improved site stability from the proposed pool addition. Therefore, requirement No. 2 appears satisfied by the combination of the consultant's report and the E&nonds Landslide Hazard Map. Summary It is our opinion that the referenced report meets the requirements for a Critical Area Study as specified in the City of Edmonds Critical Areas Ordinance. It should be noted that the scope of services performed by HWA was limited to a site reconnaissance and review of the referenced documents. Field studies and/or verification of calculations were not performed; accordingly, we can offer no assurances regarding the performance of the site. In addition, the services performed consist of professional opinions made in accordance with generally accepted geotechnical engineering principles and practices. 95084-2.DOC 3 HONG WEST & AssoclATEs, INc. June 1, 1995 0 HWA Project No. 95084-200 .0 % We appreciate this opportunity to be of service. If you have any questions, or if we can be of further service, please do not hesitate to call. Sincerely, HONG WEST & ASSOCIATES, INc. 0, �c Sti° l011ALENGi[� EXPIRED Anare 17. Mare, Y.r-. Geotechnical Engineer ADM.SLH:adm 95084-2.DOC 4 HONG WEST & AssociATEs, INc. g:«e� co o yI U U o �S� � d{ C'f � ¢ 7_fiRp ffi LLJ U yw pU U O Q ZE ( d ...../ r D '4-4 _e o I GARAGE POWDER LAUNDRY ENTRY KITCHE� FAMI ss �� r�l LIVING 'xDINING — x� / NOOK �� �, • DECK I TU IN 9L c' ,�,• /� tit_ Ile .3s-1!!1 r . '14 ll� � 0 • �REETFILE APPLICATION ROUTING FORM FILE: #V-95-43 AND CHECKLIST FROM: PLANNING ROUTED TO: �B:UII,D,ING (iF,iYi)� ENGINEERING 3/29/95 FIRE DEPARTMENT 3/29/95 �9g PUBLIC WORKS 3/29/95 PARKS & RECREATION 3/29/95 COMMENTS: Owner DR. DAVID SPIRO Property Address 15631 75TH PLACE WEST Date of Application 3/27/95 Type REASONABLE USE EXCEPTION X Application X Fee X APO List Title Report Vicinity Map Elevations Petition (Official Street Map) 94-164Critical Areas Determination COMMENTS Site Plan for Short Subdivision (8.5 x 11) X Site Plan (11 x 17) Legals (Existing & Proposed) Environmental Assessment Proof of 2-Year Occupancy (ADU) Declarations (Variance & C. U. P.) Environmental Checklist city of edm6n1s land use application i t:";? L 7 d� ❑ ARCHITECTURAL DESIGN BOARD ❑ COMP PLAN CHANGE ❑ CONDITIONAL USE PERMIT ❑ FORMAL SUBDIVISION ❑ HOME OCCUPATION ❑ LOT LINE ADJUSTMENT ❑ OFFICIAL STREET.MAP AMEND ❑ PLANNED RESIDENTIAL DEVELOP. ❑ REZONE ❑ SETBACK ADJUSTMENT ❑ SHORELINE PERMIT ❑ SHORT SUBDIVISION ❑ STREET VACATION R VARIANCE RC-.ASc 1,15 � ' ❑ RESUBMITTAL FILE # FILE # -43 ZONE —2-0 DATE o REC'D BY FEE 1&/�2- .t]C2 RECEIPT # HEARING DATE 9HE ❑ STAFF ❑ PB ❑ ADB . ❑ CC ACTION TAKEN: ❑ APPROVED ❑ DENIED ❑ APPEALED APPEAL # Applicant Cz S D AV t O Sp tc-- Z) 1 -Phone Address i �3i _1S t-" t? L V� t � 6 Vio tin aS , �.�iJYf:&A, Ci%02 G Property Address or Location Sa N1 F Property Owner Phone Address Age n ALO ii Sl hQ Phone -- Address 2�V'�t �RLLi►JGF.� �P 1.l•� �rl-1+�.�1Sst�S Tax Acc # 'S \33 _0 D O --C12S — 0-501-1 Sec. Twp. Rng. Legal Description S t�z Q{ to e u E ufi Details of ProjectorProposed Use UAAS . t ►J C DICE. ►1 Cal L,�4 'A)ooL,ills iacZiaA o �--A6-5 Yoc;L 1s lz� t��nv_ t tN A-4 ARf-A V3(Tr Este 11AtLP A-5 "5F-F t iA01<- The undersigned applicant and his/her/its heirs, and assigns, in consideration of the processing of the application agrees to release, indemnify, defend and hold the City of Edmonds harmless from any and all damages, including reasonable attorney's fees, arising from any action or infraction based in whole or in part upon false, misleading, inaccurate or incomplete information furnished by the applicant, his/her/its agents or employees. The undersigned applicant grants his permission for public officials and the staff of the City of Edmonds to enter the subject property for the purpose of inspest�on and posting attendant to this application. SIGNATURE OF APPLICANT/OWNER/ MASTER POOLS" • MAR 2 8 1995 JPZjjMjT CO�1 JEER March 28. 1995 City of Edmonds cg, Ogmkofdmy &ham Variance items 20.15B.50 page 267-12 Item "C" Reasonable use exception response. 1. This ordinance will not deny reasonable use of this property. Presently a family resides in a recently constructed dwelling. 2. Our findings say the placement of this shallow depth lap pool serve very little impact on either critical area or its buffer. 3. There is no threat to public health, safety or any person welfare on or off this property. 4. Yes, this lap pool addition is minimized making this space usable, in responding to set backs. 5. This proposal will comply with federal, state and city controls and restrictions. 6. This paragraph does not apply to this applicant. 7. Yes. For Dr. & Mrs Spiro. 4RaThank you 1p Simonds -30031 }3allkwer Read N.E. • Searrle, Wia Iiin�qnn 98155 • 206-365.3337 • Fix 206-361-2731 MASTER POOLS` • February 8, 1995 Hearing Examiner City of Edmonds 1-Q,0Kark ofYxruIw y Gmftsamh' Subject: Variance Request for Dr. & Mrs. David Sprio. 0 2 7 INS.915 wi..41T J. v : oa7 1 This letter is responding to applicants declarations expressing satisfaction of criteria to the City of Edmonds to issue this building permit. 1. This property is designed "steep slope hazard area". The butter set back area encompasses most of the lower portion of this lot. A variance must be granted for any development with in this buffer set back area. 2. This should not be deemed special privilege. This criteria and findings for the placement of this pool are acceptable by all the information that is know 4.Other properties in the vicinity must acknowledge that a permit on my address for this pool is not special privilege. 3. We would assume that if this Variance is granted the City of Edmonds will make sure its consistent with the comprehensive plan. That includes the compliances, for our areas, announced by the Planning Dept. for the City of Edmonds. 4. This approval will be consistent and comply with the zoning ordinance and the zone district where we live. 5. This variance will not impact or be detrimental to anyone. Namely public health, safety, or welfare to those who live in the neighborhood. Also this variance will not cause loss of any dollar value, views or affect adjacent properties. 6. We have one location for this lap pool. We are at maximum and there is no alternate available to place this lap pool. "hank you R 1ph Simonds N &-� \�\Z S �C\�-:IO 20031 Ballinger Rind N.E. • Seattle, lY/asl)injon Q8155 o 200-16;-3317 0 Fax 206-361-2731 1t7tworyoo,f frD�lo w rm :.ADD. V -�- 1.0 m ro,F . 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Z O Z Z H y � W 0 U W it (n W Z Q U ?i • U) Z O 0 WQ� W 2 a i O •a Z a m Z X g W W 0 a Z W Z y m .J U. y tN Project Number 1966 IMP CONSULTING ENGINEERS 20 March, 1995 CLIENT David and Jody Spiro ADDRESS 15631 75th Place W Edmonds, Washington 98026 REFERENCE Proposed lap pool SUBJECT Geotechnical engineering INTRODUCTION On 28 June 1994, during a telephone conversation with Dale C. Hemphill, David Spiro authorized HEMPHILL CONSULTING ENGINEERS (HEMPHILL) to conduct geotechnical engineering for the proposed lap pool to be located approximately as shown in Figure 1. page 1 of 3 pages The purpose. of the geotechnical engineering is to review the geotechnical report for the residence dated 10 December 1990, and to present geotechnical recommendations for the construction of the pool. INVESTIGATION The proposed lap pool will . be approximately 12 feet wide, 44 feet long, and 4 to 6 feet deep. The pool will be located approximately as shown in Figure 1 between the house and the 35 foot setback from the west property line. A test boring conducted near the pool during the investigation for the house _revealed that the 15 feet under the proposed pool is composed of wet medium dense silty fine sand. The upper soils that will be excavated for the pool are composed of wet loose gravely sand. 4041 WEST LAKE SAMMAMISH PARKWAY SOUTHEAST • BELLEVUE • WASHINGTON • 98008 • 206 6441080 Project Number 1966 20 March, 1995 page 2 of 3 pages CONCLUSIONS & RECOMMENDATIONS HEMPHILL concludes that the soils under the pool will be capable of supporting the loads, considering that the 100 to 120 pcf soils will be replaced with 60 pcf water, and that the pool loads will be spread out over the entire base of the pool for maximum bearing pressures of 360 psf. Medium dense sandy soils can support minimum loads of 1000 psf, and they presently support a minimum of 600 psf. During the construction of the house the slope from the house to the railroad was considered to be potentially unstable under unusual storm or seismic conditions. The construction of the house improved the stability of the slope by installing retaining walls, deep piles, and drainage. The installation of the pool will also improve the slope stability by removing approximately 400,000 pounds of soil and adding 200,000 pounds of water at the head of the slope, the most critical area, and by installing additional drainage. The stability of the lower portion of the slope will be improved when that parcel is developed. Because of the wet conditions encountered while conducting the boring, HEMPHILL, recommends that the pool be lined with drainage, as shown in Figure 2, to lower the adjacent water levels, and to prevent floating of the pool. Also to prevent the pool from damming any drainage from the east slope. The drainage can be composed of several inches of clean drainage gravel around the sides and bottom of the pool. The drainage gravel should be surrounded by filter fabric between the gravel and the adjacent soils to prevent the infiltration of the adjacent soils into the gravel, preventing clogging of the drainage system and voids around the pool. HrE' T � r1-15�H-9 �II,1; Project Number 1966 20 March, 1995 The pool drainage system should be connected to a gravity outlet drain to conduct any intercepted groundwater or leaking water to the roadside drain ditch as shown in Figure 2. Any intercepted water will be minimal, and will have little or no impact on the drainage ditch. Crushed rock can be placed at the outlet of the drain pipe into the drain ditch to reduce the velocity of any water and to prevent any scouring. The pool can be located anywhere between the deck footings and the 35 foot setback. If the excavations for the pool are within a 450 line of influence of the deck footings, then the deck should be supported with temporary supports placed beyond the 451 zone of Dale C. Hemphill P.E. Registered Engineer No. 14777 State of Washington page 3 of 3 pages influence. If necessary the existing deck footings might be replaced with relocated supports approved by HEMPHILL. HEMPHILL should verify that the soils and groundwater conditions are as anticipated, and to present alternative recommendations if conditions are different. HEMPHILL concludes that if the pool is constructed in accordance with the plans and with recommendations presented in this report, and with any recommendations by HEMPHILL at the time of construction, that the pool will be safe, and the stability of the slope will be improved. of WAS 14777 'rf�NAL EXPIRES 17 FEBRUARY 1996 HrE-'1�/Ir�HrIrL L r storm Drainage Fee Street Use Permit Budding Permit (Type) i �f LANDAU '�'Q FILE• ASSOCIA,� •E A INC. Geoenvironmental Engineering and Technologies°° APR 19 1991 April 19, 1991 Pi RMIT COUNTER City of Edmonds 250 Fifth Avenue North Edmonds, WA 98020 Attention: Ms. Jeannine Graf RE: SUPPLEMENTAL GEOTECHNICAL REVIEW PROPOSED SPIRO RESIDENCE 15631 75TH PLACE WEST MEADOWDALE AREA EDMONDS, WASHINGTON This letter presents findings, conclusions, and recommendations concerning a supple- mental geotechnical review of project plans, reports, and other documents concerning the above proposed project. A summary of documents we reviewed is included as Attachment 1. . Preliminary geotechnical review comments were provided by Landau Associates in a February 12, 1991 letter. A March 6, 1991 response by Hemphill Consulting Engineers (Hemphill) satisfactorily addresses most of these review comments; however, there are still several issues which are either unresolved or for which the response to date is inadequate. The issues are discussed below and are listed in the numerical order presented in our February 12, 1991 preliminary review letter. A copy of that letter (attached) and the March 6, 1991 reply by. Hemphill (also attached) must be referenced for a proper understanding of this letter. 1. The historical information has been provided by David and Joanne Spiro. 2. The response by Hemphill is not clear and appears to contain contradictions. Hemphill states that only the north portion of the interceptor drain has flow and that this (north) segment is located on adjacent property., The response goes on to state that the drain is above the sand/clay contact and that if water is moving at this contact, it could not be intercepted by the present drain system. The drawings we have reviewed indicate that the entire drainage system is on the subject site; therefore, if the northern leg of the drain does in fact contain flow, the source must be either: a) onsite ground water or b) surface flow which is being diverted P.O. BOY 1029 • EDMONDS, WASHINGTON 98020.9129 • (206) 778-0907 • FAX (206) 778-6409 into the system. If the drawings are in error or if surface water is being introduced into the system, a simple design clarification or minor onsite drainage modifications will address the present concern. If, however, it is determined that the north leg of the drain is on the subject site and does intercept ground water, abandonment of the drain could negatively impact downslope properties. For this reason, it is our opinion that the City should require that the applicant clearly demonstrate: a) where the drain is located, b) where the source of flow is from, and c) how proper abandonment or relocation will be accomplished (whichever is deemed appropriate). 3. Hemphill's response concerning the Esperance sand and Whidbey clay contact elevation is consistent with geologic mapping by others. Hemphill's response concerning the 30 degree dip noted in the bottom sample of Boring 2 is based on an interpretation that the failure plane(s) at the site are shallow. While this interpretation may differ from other investigators, the present interpretation, which is based on site -specific information by the design professionals involved in this project, is considered acceptable at this time. 4. Revised contours shown on (resubmitted) Figure 1 clarifies previous data gaps; however, the source of the site topographic information is still uncertain. While technically the City could require a topographic map prepared by a licensed surveyor, such a request may not be justified at this time. It should be noted that revised topography east of the proposed soldier pile retaining wall (near its north end) shows slopes which are steeper than 1HJV (horizontal:vertical). 5. The response by Hemphill indicates that structural calculations have been submitted to the Edmonds Building Department; thus, we are assuming that the City will provide review services for the various structural elements. Other items noted in our preliminary review letter include: a) the plans are undated, b) plans with structural details are not stamped by a licensed structural engineer, and c) certain plan details are missing scales. These are items for which the City can determine specific requirements. 6. The response by Hemphill states that the project plans have been revised to show the required pile data for construction purposes. The pile information was not provided to 04/19/91 EDMONDS\SMRO.RVW 2 LANDAU ASSOCIATES, INC. Landau Associates for review; thus, the City must determine if sufficient detail has been provided to meet City requirements. Landau Associates does not agree with the method used by Hemphill for pile design; however, placing the proposed residence on a pile foundation is much preferable to shallow footings. Therefore, assuming that: a) adequate pile details have been added to the project plans, b) the short piles referenced by Hemphill are not used, and c) an experienced field representative from Hemphill is present during pile installation, unresolved questions concerning the methods used to calculate pile capacities should not negatively impact this or neighboring properties. The owner and designers must, however, be aware that the risk to the structure from slope instability has not been eliminated by placing the house on piles. 7. The response by Hemphill concerning design of the proposed soldier pile wall states that the wall is designed to support horizontal compacted backfill and some minor slough debris. Revised topographic information provided with the resubmittal shows that the existing slope is steeper than 1H:1V in places. There has been no exploration of the slope above the proposed wall and if Test Pit No. 3 (which is the closest exploration to the proposed wall) is representative of soil slope conditions, a substantial portion of the wall may be support colluvium rather than undisturbed Whidbey clay. Throughout the Puget Sound region there have been numerous slope failures which were attributed to removing supporting soil from the toe of a hillside. The proposed retaining wall will result in removal of soil from the toe of such a slope. Thus, there is a significant risk of slope failure if: a) construction is not done in the proper sequence, b) construction is attempted during unfavorable weather conditions, or c) the permanent retaining wall is underdesigned and fails. A slope failure at this site could easily propagate onto neighboring properties. In our opinion, the present wall design is based on assumptions and lateral soil pressures which have either not been demonstrated to exist, or for which contradictory information has been provided. For these reasons, we recommend that the City require the designers to: a) provide specific Project Plans for the proposed soldier pile wall, b) provide further justification why a design based on horizontal backfill is appropriate (when topographic information suggests that a substantial slope surcharge may be 04/19/91 EDMONDS\SPIRORVW 3 LANDAU ASSOCIATES, INC. applicable), and c) explain why revised contours at the south wall transition show a proposed slope steeper than recommended by Hemphill. Details concerning design of the soldier pile wall can probably be completed while site work and pile installation are in progress. For that reason, it may be acceptable to allow construction to begin subject to further review. 8. The response by Hemphill is acceptable. 9. The response provided by Hemphill is acceptable; however, it should be noted that placement of fill atop previously failed materials is typically considered of questionable engineering practice. We have assumed that the design engineers have thoroughly assessed the effects of the load from this fill and have concluded that such filling is acceptable. 10. The response by Hemphill is acceptable. 11. The response by Hemphill puts the owner on notice that slides from the eastern hillside are possible. It is our opinion that stating the potential for such slides constitutes an acceptable response. 12. The response by Hemphill states that most of the east slope within 20 feet of the proposed soldier pile wall is less than 30 degrees. While this may be the case at the south end of the proposed wall, there are places near the north end of the proposed wall where the slope is in excess of 100 percent. 13. Revised drawings showing detailed drainage plans were not submitted for review. Hemphill states that drainage details have been added to the project plans; therefore, the City should determine if the level of drainage detail is adequate, or if additional review by Landau Associates is needed. 14. The Hemphill response is adequate. 15. Responses by Hemphill are adequate. 04/19/91 EDMONMSPIRORM 4 LANDAU ASSOCIATES, INC. In summary, a majority of outstanding issues have been addressed in Hemphill's March 6, 1991 letter. The two outstanding issues, which in our opinion will require additional input, are: 1) the existing interceptor drain, and 2) the proposed east retaining wall. There are several items addressed herein for which the City may or may._ not feel comfortable providing the final review services. Should you have questions concerning any of those issues, or have other questions or comments, please do not hesitate to call. WDE/sg No. 74-24.10 04/19/91 EDMONDS\SRRORVW 5 Very truly yours, LANDAU ASSOCIATES, INC. By: William D. Evans, CPG Senior Geologist LANDAU ASSOCIATES, INC. ATTACHMENT 1 • Sheet 1 of the Project Plans, Design Works Construction, undated (revised from submittal) • Letter, Addendum to Geotechnical Report, Hemphill Consulting Engineers, December 24, 1990 • Letter, Response to Geotechnical Review, Hemphill Consulting Engineers, March 6, 1991 • Historical Information, David and Joanne Spiro, March 11, 1991. 04/19/91 EDMONDS\SPIROXVW STREET FILE MITIGATED 0 DETERMINATION OF NONSIGNIFICANCE Description of proposal Single Family Residence Proponent David & Joanne Spiro 7711 171st St. SW., Edmonds, WA 98026 Location of proposal, including street address, if any 15631 75th P1. W., Edmonds, WA 98026 Lead Agency Edmonds Planning Division FILE# N/A 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 (EIS) is not required under RCW 43.21C.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. There is no comment period for this DNS. x This DNS is issued under 197-11-340(2); the lead agency will not act on this proposal for-15 days from the date below. Comments. must be submitted by March 7, 1991 Responsible Official John Bissell Position/Title Code Enforcement. Tech. Phone 771-3202 Address 250.5th Ave. N., Edmonds WA 98020 Date February 20, 1991 Signatur X You may appeal this determination of nonsignificance to Hearing Examiner at 250 5th Ave. North, Edmonds, WA 98020 no later than.5:00 p.m., March 17, 1991 by filing a written appeal citing reasons. You should'be prepared to make specific factual objections. Contact John Bissell to read or ask about the procedures for SEPA appeals. -There is no agency appeal. CONDITIONS OF MITIGATION SPIRO BUILDING PERMIT, PLAN CHECK #247 This determination of nonsignificance is subject to the following conditions: 1• All excavation and grading shall comply with Chapter 70.of the Uniform Building Code, 1989 edition. 2. The Applicant shall obtain a building permit from the Building Department and shall comply with all conditions of permit approval. 3. The Applicant shall submit a drainage plan to the City Engineering Division and follow the required guidelines. 4. The applicant shall follow the requirements and guidelines of the City of Edmonds Engineering Division. 5. The applicant shall follow all recommendations of Hemphill Consulting Engineers, project number 1636 report dated December 10, 1990 and addendum dated December 24, 1990. 6. A geotechnical engineer from the reporting firm shall be retained on site during all excavation and the contractor shall follow all recommendati� onsOf said' and engineer on site. 7• The applicant shall provide the City with a clearin a relandscaping plan. The relandsca in g plan and timetable for completion. p g plan shall include a prior to occupancy of the structurescaping must be complete 8. The Applicant shall make every reasonable effort t exposed soil covered during construction. ° keep 9. The Applicant is to make every possible effort to keep controlled and to keep the streets clear of dirt and debris. JOHN A GRIFFIN E INE CIVIL/STRUCTURAL CONS ERS, INC. 11680 SLATER AVENUE NINE G ENGINEER KIR, WASH NGTON 98034 (206KLAND) 823-9903 FAX (206) 821-9408 STREET FILE PROJECT: DR. SPIRO POOL - EDMONDS, WA. STATEMENT REGARDING PpOL DESIGN I HAVE READ THE ENGINEERS AND GEOTECHNICAL REPORT ACCORDING TO HU 14DERSTAND THAT IF THE IS HEMPHILL MPHILL S BY THAT „INSTALLED WILL BE SAFE AND THE IMPROVED." STABILITY OF .THE THE POOL SOILS AND HEMPHILL STATES SLOPE WILL BE GROUNDWATER CONDITIO SE DURING EDS TO VERIFY THE THE POOL. CONSTRUCTION OF 890.19Ci STREET FILE 0 CITY OF EDMONDS 250 - 5TH AVE. N. • EDMONDS. WA 98020 • (206) 771-3202 COMMUNITY SERVICES: Public Works • Planning • Parks and Recreation • Engineering March 29, 1991 David and Joann Spiro 7711 - 171st St. S.W. Edmonds, WA. 98020 Re: Site restoration bond and sidewalk waiver 15631 - 75th Pl. W., Edmonds Dear Mr. and Mrs. Spiro: TARRY S. NAUGHTEN MAYOR PETER E. HAHN DIRECTOR Thank you for your letter dated March 27, 1991. The original estimate for the subject address site restoration is a reasonable amount for the work involved if all improvements are complete and the total recon- struction required. Because the road widening and sidewalk installation most likely will not occur during the construction of your single family residence, I had the staff revise the estimate to reflect . restoration of existing conditions. The revised bond requirement is $53,000. Regarding the subject sidewalk waiver, a sidewalk will be constructed along 75th P1. W., but because development is sporadic in that area, we are not requiring sidewalks to be constructed at the time the house is constructed. Instead, we require cash set aside and this money is placed in a special account for construction of the sidewalk at a later da me prior to f' nspection and based on your frontage wi , amount required is $860. If you have any questions, please call Lyle Chrisman at 771-3202, extension 289. Sincerely, ROBERT J. ALBERTS, P.E. City Engineer LC/sdt SPIR02/TXTST530 • Incorporated August 11, 1890 o Sister Cities International — Hekinan, Japan Date: March 11, 1991 To: City of Edmonds MAR From: ''David and Joanne Spiro PERMIT counTc Re: Historical information, file 247, 15631 75.th Place West The question was raised by Landau and Associates in their review of our geotechnical report about the whereabouts of the house that once stood on our property, since there are concrete steps indicating that a house once stood there. Their concern is that the house may have slid away during the landslide -of 1945. The fact of the matter is that the house stood firm during that time, but was lost to fire on March 2, 1973. An article from the local newspaper describes this fire, "A 50-year-old two-story frame house at 15631,75th Place W., owned by D. H. Caryl, who lives in another house nearby, was completely destroyed by a fire that apparently began in the front section." --Saturday, March 3, 1973,.Western Sun Edition. OPEET FILE. 0 Date: March 27, 1991 ENGINEERING To: Lyle Chrisman, City of Edmonds From: David and Joanne Spiro Re: Site restoration bond for 15631 75th.Place West Thank you for your letter of March 21. We are of the opinion that your requirement for a $75,000 site restoration bond seems excessive; and we.are asking -that this figure be dropped to $25,000. We have inquired of both Dick Mumma and Jeannine Graf at the building department who have told us that other building projects in the Meadowdale slide area have been asked to post bonds in the area of $25,000. We also consulted a land use attorney, Greg Lawless, who affirmed the notion that $25,0 0 would be a reasonable bond. request but that amounts above that figure would be open to question. Furthermore, we have at great expense engaged Hemphill Consulting Engineers to conduct a geotechnical investigation of our lot and to make recommendations based on objective findings to minimize disturbance of the soils and in fact to stabilize the land both during construction and after our home is completed. In addition, we have a liability policy with State Farm Insurance in the amount of $ 1 million for damage should it occur. Because of these facts, the additional expense of procuring a site restoration bond in the amount of $75,000 seems excessive and in fact punative. We respectfully request that the figure be reduced to $25,000. cc: Dick Mumma Scott Snyder STREET FILE - _ r CI-AIL1 I �i ITNEER�S9 INC. VIL%STRUCTURAL CONSING ENGINEER 11680 SLATER AVENUE NE HIRKLAND WASUNGTON 98034 (206) 823-9903 rAX (206) 821-9408 STREET FILE ---- mvEo PROJECT: DR. t SPIRO POOL - EDMONDS, STATEMENT REGARDING POOL DESIGN I HAVE READ THE ENGINEERS AND UIT ERS END ,T HNICAL REPORT By HEMPHILL ACCORDING TO HE ��' IF THE POOL IS INSTALLED WILL BE SAFE MPHILL S RECOMMENDATIONS THAT 11 IMPROVED." AND THE STABILITY OF THE THE POOL HEMPHILL STATES HE SLOPE WILL BE EEDS SOILS AND GROUNDWATER CONDITIONS DURING TO VERIFY THE THE POOL. CONSTRUCTION pF monmJAN1��/ 19 - S•�jrq M N c �`�.��1�'Y'f � O �J LARRY S. NAUGHTEN -.. �._... i 250 - 5TH AVE. N. • EDMONDS, WA 98020 • (206) 771-3202 MAYOR COMMUNITY SERVICES: PETER E. HAHN ! Public Works • Planning • Parks and Recreation • Engineering DIRECTOR 8gp-1q March 21, 1991 David and Joann Spiro 7711 - 171st St. S.W. Edmonds, WA. 98020 Re: Driveway slope waiver and site restoration bond 15631 - 75th P1. W., Edmonds Dear Mr. and Mrs. Spiro, Your request for subject waiver has been reviewed, and although we prefer to keep driveway slopes below 14%, increasing slope cuts may create additional problems. Therefore, your request for a driveway slope waiver is granted. The slope shall not exceed 18% in any area of the driveway. Due to the sensitivity of the area, it will be necessary for you to post a site restoration bond to repair any damaged utilities and pavement surfaces across your property frontage should a slide occur�-\%\ during construction. An estimate of $75,000 has been tabulated to cover total restoration of all utilities and pavement surface. Please submit the required site restoration bond. If you have any questions, contact Lyle Chrisman at 771-3202, extension 289. Sincerely, ROBERT J. ALBERTS, P.E. City Engineer LC/sdt SPIRO/TXTST530 STREET FILE s Incorporated August 11, 1890 :sister Cities International — Hekinan, Japan HEM O H I L L CONSAI NG ENGINEERS La h- N W o o PROJECT NO. 1636 6 March 1991 page 1 of 6 pages 0_ ° RECEIVED 1- N - t W Q N -- MAR 1 2 1991 io i ; CLIENT David Spiro m W i 19405 89th Place West LANDAU ASSOCIATES,INC. n ° W Edmonds, Washington 98020 i. o z 2 REFERENCE : Proposed Spiro house J Q IA J Q 0 SUBJECT Response to geotechnical review per, l COUNTER W w 0 N o o INTRODUCTION rr Q Q 3 w J a The purpose of this report is to present corrections to, or clarify, the geotechnical report titled Z c w "Geotechnical Engineering for the Proposed Spiro Residence' dated 10 December 1990, by HEMPHILL o Z w CONSULTING ENGINEERS, in response to a geotechnical review by LANDAU ASSOCIATES, Q ¢ t INCORPORATED. 0 0 W The geotechnical report, and the review, are in accordance with requirements by the City of Edmonds for proposed construction within the Meadowdale portion of Edmonds. Z � w o wring a conversation with William Evans of Landau Associates, HEMPHILL became aware that some w W �, information that was either obvious to HEMPHILL because of familiarity with the project, or that Z N Z HEMPHILL considered to be insignificant, was not clearly presented in the geotechnical report. Also it Z ? o was determined that it would be necessary for LANDAU ASSOCIATES to have a better understanding of W Z z some decisions that would be determined at the time of construction. Those decisions would be made Y0 Wby HEMPHILL but it would be necessary for the City of Edmonds to require that those investigations and 0 Q Q decisions be made by HEMPHILL in accordance with recommendations presented by HEMPHILL on the I a last 2 pages of the geotechnical report. m Cr Z W o W Q 3 HEMPHILL SUBMITTED a supplemental letter DATED 24 December 1990 that presented a statement of risk in accordance with City of Edmonds standards This response is presented in the numerical order of the questions and comments presented in the o o LANDAU review dated February 12, 1991. Z W Q a C3 Z 0 m RESPONSE d a Z x Q J - w w o 4 ? 1. Historical information is being presented by David Spiro. HEMPHILL briefly referred to the history 4 LL Cl W of the site on page 9 of the geotechnical report with the statement "The largest recorded slide z occurred in 1945 when large movements occurred in this gully.....'. This .gully includes the site and o 0 all downhill property. Although the slide would have improved the stability of the site, along with tL m the removal of septic systems, HEMPHILL recommended construction procedures and a 0 foundations based on the potential of instability at the site regardless of the present stability. 921 109TH AVENUE S. E. • BELLEVUE, WA. 9B004 • 453 4760 PROJECT NO. 1636 6 March 1991 page 2 of 6 pages 2. The existing interceptor drain has been monitored on numerous occasions during different seasons and rainfall conditions. Flow was never observed from the portion of the interceptor drain south of the outlet pipe shown on Figure 16 on page 15. The portion of the interceptor drain north of the outlet pipe, which is located on the adjacent property to the north, has always had flow. The interceptor drains at this site were installed without any recommendations or inspections by a geotechnical engineer. HEMPHILL has concluded that the portion of the interceptor pipe on this site was placed above the sand/clay intersection. The top of the clay is lower at this site either because the site slid in the past, or because the site was a drainage channel, that then was filled with beach deposits. The top of the clay is higher on the site to the north. If the water is in fact moving on top of the clay, then the water cannot be feasibly intercepted at the present location of the interceptor pipe, or to the west. The top of the clay is more easily intercepted closer to the exposed clay at the east side of the site. Whether the groundwater is intercepted or not will not change downslope conditions since the present interceptor pipe is not functioning. If the groundwater can be intercepted easily at the time of construction then near surface conditions will be improved. If the groundwater is too deep to intercept, as it apparently is now at the location of the interceptor pipe, then intercepting the deeper water is not necessary. Figure 16 on page 15 shows the present location of the interceptor drain. Figure 51 on page 59 shows the proposed location of the new interceptor drain. The existing non functioning drain will be disconnected from the outlet pipe and abandoned. ` 3. The boring logs presented in the geotechnical report show that the fine sands that overly the hard clayey silt exist in a wet condition, which indicates near saturation to depths of 15 to 20 feet. The inference is that groundwater exists above the 'top of clay' as described in the geotechnical report. The groundwater blends from surface infiltration to capillary water to free groundwater. Site stability studies and the design of lateral resisting piles were based on conservative soil values, on the depths of the poor standard penetration values, wet soil conditions, and top of hard clay, resulting in a conservative line of stability of 1 vertical to 4 horizontal shown in Figure 23 on page 26. HEMPHILL assumed that everything below that line will be stable. Although the line of stability ranges from 4 to 12 feet below the existing ground surface, HEMPHILL designed piles based on the potential for all the fine sands to slide, and for the hard clay to provide lateral resistance for the piles. The piles were designed to resist 17 feet of potentially unstable soils. Since the piles are designed to resist all the soils that are wet, and since future drainage at the site will decrease surface infiltration and will possibly improve groundwater and will decrease driving soils, then downhill stability will be improved regardless of any existing groundwater conditions. HEMPHILL C, • PROJECT NO. 1636 6 March 1991 page 3 of 6 pages The 30 degree dip in the recovered sample is insignificant since it is 32 feet below the line of stability and is within hard clay that had penetrometer values in excess of 10,000 psf. The statement that the contact between the Esperance Sand and the Whidbey Clay was observed at 150 feet is an error. The contact was observed south of the property at elevation 250. That contact is significantly east of the site and above a large drainage system that was installed west of 164th Street SW. 4. More accurate topographic data has been presented on a revised topographic plan. There was some confusion because of the obvious differences in the topographic plan elevations and the elevations of proposed portions of the structure and the soldier pile wall. The true conditions were obvious during preliminary site visits when designs were discussed, and the topographic differences in the plans were ignored. One location for concern was what appeared to be the south slope being supported by the frame of the structure, but the view from the west in Figure 6 on page 6 shows that the portion of the house that appears to cut into the slope in the plan view is actually the second floor, and the first floor is located 10 feet inside that location. The south slope will be excavated to create a dog run, and the cut will be supported by a low concrete wall. 5. Structural calculations have been submitted to the Edmonds Building Department and have been accepted by Whitley Jacobson Engineers. 6. The project plans have been revised to show the required pile data for construction purposes. The 30 degree dip in the recovered sample is insignificant since it is 32 feet below the line of stability and is within hard clay that had penetrometer values in excess of 10,000 psf. The cause of the dipping could be natural or a chunk that collapsed into the boring, but regardless of the reason for the sample, because of the depth below the line of stability, and the strength of the adjacent soils, the effects are insignificant and not worth extra costs to pursue. The method used to design the piles is based on the procedures presented originally by Brohms in 1968. The beam on elastic foundation method was a forerunner of the Brohms method, which began with the design of the deflection of railroad tracks by Timoshenko in the 1800's. The method used to design the lateral resisting piles includes the relative stiffness of the pile in the calculations, therefore the deflection of the shorter piles does not return to zero, as shown in Figure 37 on page 45 where the bottom of the 25.7 foot pile has a deflection of-0.217, and the bottom of the 38.8 foot pile is strained to zero deflection. A plot of the deflections shown in Figure 37 will show the deflections of the shorter piles to be nearly a straight lime, while the longer piles bend significantly by comparison. The pile deflections are not independent of the soil strains. The soil and the pile must work together as a unit. Adding an extra length to the bottom of the pile changes the deflections throughout the system showing the influence of the soil beam combination. H E M P H I LL • PROJECT NO. 1636 6 March 1991 page 4 of 6 pages Over -consolidated soils do not have a changing rate modulus, but the method uses an adjustment to change a constant rate soil to an equivalent changing rate soil. The method of applying active pressures against a pile are not appropriate because the stronger the soil the lower the active pressure, which is directly opposite to what actually happens. The stronger the soil the greater the pressure against the pile. The design of the slide forces against a pile are similar to the method of designing a rivet. Assuming that the top of the slide is not near the pile, and that the slide actually moves without hanging up (which is the worst condition that can occur), then the stronger the soils the greater the drag on the pile. If the proper soil parameters (cohesion and friction) are used, then the stronger the soil the greater the drag around the pile. If active pressures are used then the stronger the soil the lower the pressures against the pile. The calculations shown in Figure 37 on page 45 show the deflections, bending moments, and shear for various depths of placement of the same pile. HEMPHILL usually places piles at depths into over -consolidated soils at least the depth of potential slide soils, depending on the relative strengths of the driving and resisting soils. The recommended depths of piles are described in Figure 32 on page 40; therefore the shorter piles will not be used. The final depths will be determined at the time of construction as the true conditions are revealed for each pile. 7. The soldier pile wall is designed to support a horizontal compacted backfill and some minor slough debris. The hard Whidbey Clay will not apply pressure against the wall as a cohesionless soil would, therefore the potential for a slope failure is not considered in the design, and the slope of the Whidbey Clay is ignored in determining the lateral forces on the wall. The transitions for the ends of the wall have been included in the revised drawings. The statement that the spacings will be determined after the excavations have been completed is in error. The statement should read that the spacings will be determined after the proposed depth of excavations have been determined, or 4 the wall is moved into or away from the slope at the time of construction because of conditions, then the height of the wall will change, which will also change the spans, as shown in Figure 44 on page 50. 8. After careful review of the areas to be excavated, we have determined that the amount to be excavated for the construction of this project are accurate. The detention system is considered a utility and therefore not included in the calculations in accordance with Edmonds building code. The grade beams will be placed at or near grade, requiring little or no excavation. The total excavating will not exceed 500 yards. 9. The placement of fill along the west side of the site will be much less than the volume to be - excavated and will have no detrimental effect on the stability of the site, especially considering the other improvements that increase the site stability far more than any decrease from the fill. H E M P H I L L PROJECT NO. 1636 6 March 1991 page 5 of 6 pages To resist lateral loads the piles are far overdesigned for vertical support and are capable of supporting loads of 80,000 pounds using conservative values of 6000 psf end bearing and 1000 psf side friction within the Whidbey Clay. Assuming a heavy equivalent pressure of 50 pcf and a high friction factor of 0.5, the greatest downward drag on the piles would be 13,000 pounds. That assumes full mobilization along the entire length of the upper sandy soils. 10. The drawings have been changed to show the rockery in accordance with recommendations by HEMPHILL. The standard detail by the City of Edmonds will allow a rockery to be build that will fail- 9 build to the worst allowable conditions rocks are cubic shaped. 11. Slides in Whidbey Clay and Lawton Clay are generally the result of shallow surface slides which result from the weakening of the upper 2 to 3 feet of soils due to weathering (wetting and drying, freezing and thawing, root action, direct rainfall). The debris slide is generally local and does not include a large area. The more dangerous slides are flow slides resulting from complete saturation of loose soils. There is no evidence that flow slides have ever occurred in the vicinity of the site. Any loose soils observed at the base of the slopes in the. general vicinity are the result of 'slope wash' which generally occurs in small quantities at a time. The potential for a larger surface slide is remote, and there is a buffer zone that will protect the house if such a slide should occur. 12. Most of the east slope that will be within 20 feet of the proposed soldier pile wall is less than 30 degrees. There was no mention in the geotechnical report of an angle of repose for the east slope. The undisturbed Whidbey Clay can stand vertically for many feet, and the slough debris can stand at angles of 1 V : 1.5H if protected by vegetation. The south portion of the existing slope is fairly stable at the bottom because it is approximately the angle of repose of the slough debris. If debris should slide over the soldier pile wall it will lie between the wall and the house. There is not requirement that the debris be removed, but the owner should be aware that there is the remote potential for debris. 13. Typical drainage plans have been added to the design drawings, but final decisions for drainage should be determined at the time of construction, and the contractor should be aware that the drainage shown on the drawings are not final. 14. Agreed! 15. A. The dates used by HEMPHILL were stamped on photographs of the large very damaging slide in the general area. —� H E M P H I L.L PROJECT NO. 1636 6 March 1991 page 6 of 6 pages B. There is no such thing as a specific blow count versus consistency. The standard penetration test (SPT) can be very misleading if not used with judgment, provided that it is accurate. If a fairly undisturbed sample is recovered, then a visual examination is more accurate that the SPT. The SPT varies with grain size, plasticity, and water content. Other factors are height of hammer, condition of spoon, side friction, pounding on chunks of rock or gravel, slumping of the hole and pounding into the debris, missed blow counts during mental lapses, you name it, I've seen it. The consistencies recorded on the boring logs were based on visual examinations of the recovered samples. The boring logs also show the results of penetration tests conducted on the samples. C. Figure 29 is a standard figure used by HEMPHILL and the 90% was inadvertently included. The intent, regardless of any given compaction, is that the grade beam should not settle enough during the curing process to be damaged or to make the placement of the upper structure difficult. After curing the condition of the soils is insignificant. D. True! Those values are for light loads from deck and stair footings. The report also includes other important design recommendations for methods to attach decks to prevent damaging the main structure during settlement, and also includes criteria which will allow those footings to be jacked back into place in case of settlement. CONCLUSIONS Except for some disagreement of design criteria for the piles, and some clarifications of poor or misleading descriptions or drawings in the report and project plans, HEMPHILL agrees that most of the comments by LANDAU ASSOCIATES were appropriate, and the responses in this report attempt to clarify the geotechnical report and project plans, or to present any omissions. Dal C. Hemphill P. E. Dal Registered Engineer No. 14777 State of Washington OQ <' wns'' (1f 2 �ss�OHAI•E� HEMPHILL STREETHLE ¢--iz_R1 So�cs ncp62l, %(¢E 5DiL-5 C+/G1NL-:-C(C H4 S DES/GAvc D 7WE s rcEL o -N 00 1 1 1 1 ` \ i 1 1 1 DRAIN LINE \ ,VEL BEHIND \ • I have reviewed the soils geotechnical i Its recommendations, have explained c the owner the risk of loss due to slides have incorporated into the design the r report and established measures to rec of injury or damage from any earth mo% the report LEGAL DESCRIPTION The North portion of Lot 25 less the East 380.73 feet the in supplemental Plat of Mea Beach. According to the PIS recorded in Volumn 5 of Pla page 42, Records of Snohoi Washington. ZONING RS-20 LOT SIZE 16,000 SO. FT. LOT COVERAGE Building and Decks 3 Total inpervious area 5 LOT COVERAGE ( percentage ) 3,376 -' 16,000 = 21 % ALLOWABLE HEIGHT CALCULAI 121.95 121.76 143.75 143.95 AV.132.74 ALLOWABLE HEIGHT = 132 EXCAVATION CALCULATIONS Area 1 1 55 "H E M FOH I L L CONSAING ENGINEERS STREET F�LE W0 N z PROJECT NO. 1636 24 December, 1990 MAR page 1 of 2 pages 0 � i= Q o n N a a Comm Y ~ J > Z (A W Q W ? CLIENT David Spiro n ° W 19405 89th Place West a o a Edmonds, Washington 98020 o N z -1 o REFERENCE : Proposed house located at 15631 75th Place West, Meadowdale . . . SUBJECT : Addendum to geotechnical report En W 0 o N INTRODUCTION W N o Q J 3 W This letter is an addendum to the report titled 'Geotechnical Engineering for the Proposed Spiro 0 z w Residence' by HEMPHILL CONSULTING ENGINEERS, and dated 10 December 1990. ] cro W N The purpose of this addendum is to present a statement of risk based on City of Edmonds standards, . . with an interpretation by HEMPHILL. Z w 0 Cl u F W W N Z Z 0 Y 0 W ~ W o D Cl Cl I n W CE Z a W UO 3 . . m o z o W W Q W Q z o m o , a Z X J W W Z U Z 0 Q ;- c ClW o 3 J LL N N STATEMENT PROBABILITY Based on the City of Edmonds Landslide Hazard Map, within the next 25 years the site of the proposed Spiro residence has a 2% probability of encroachment of slide debris from the rear slope, and a 25% probability of a slump slide occurring downhill from the proposed house. Probability statistics are not very accurate because they are based on such variables are seismic activity, rainstorms, snow melts, and other natural events that cannot be predicted with any reasonable accuracy. The actual cause of landslides can include changes or removal of vegetation, broken or leaking pipes, uncontrolled stormwater runoff erosion, stupidity of man, etc etc that can have an effect on the physical properties of the potential sliding soils. RISK of FAILURE HEMPHILL concludes that if the project is constructed in accordance with the plans, the specifications, and the geotechnical report, and in accordance with recommendations by HEMPHILL at the time of construction, then: a. the risk of major structural damage to the proposed house and garage is negligible because of the support of the lateral resisting piles. 921 TOOT" AVENUE S. E. • BELLEVUE, WA. 9B004 a 453 4760 0'- • PROJECT NO. 1636 24 December, 1990 page 2 of 2 pages b. the risk of damage to the site is reduced because of the soil pinning action by the piles, reduction of driving soils by excavating a portion of the rear bench, and reduction of groundwater by placing improved interceptor drainage, and by intercepting stormwater runoff from impervious surfaces. c. the risk of damage during construction to adjacent sites to the north and south is minimal because no excavating will occur adjacent to those properties, and the property to the east will be supported by soldier pile walls placed before excavating commenc S. d. the risk of damage to adjacent properties after construction will be improved because of support by permanent soldier pile walls, and because of the influence of the improved site. CONCLUSIONS HEMPHILL has presented recommendations and designs based on the assumption that the site is potentially unstable at any time as the result of unusual natural phenomena. The stability of the site will be improved to minimize damage to the driveway, utilities, decks, and landscaped areas. The house and garage will be structurally supported by piles placed into stable soils to eliminate the potential for major structural damage. The stability of adjacent properties will be protected during construction, and will be improved after construction because of the influence of the improved site stability. Dale C. Hemphill P. E. Lod L Registered Engineer No. 14777 State of Washington H E M P H I L L LANDAU A ASSOCIATES, INC. Geoenvironmental Engineering and Technologies City of Edmonds 250 Fifth Avenue North Edmonds, WA 98020 Attention: Ms. Jeannine Graf RE: PRELIMINARY GEOTECHNICAL REVIEW PROPOSED SPIRO RESIDENCE 15631 75TH PLACE WEST MEADOWDALE AREA EDMONDS, WASHINGTON • February 12,1991 This letter presents findings, conclusions, and recommendations concerning our preliminary geotechnical review of project plans, reports, and other documents concerning the above proposed project. A summary of these documents is. included in Attachment 1. City Ordinance No. 2661 requires the submittal of plans, reports, and other documents during -the review process. The following list summarizes documents typically needed for the geotechnical review, and provides the status of the present submittal. Document Status Owner's Liability Statement Submitted Architect's Declaration Submitted Geotechnical Declaration Incomplete declaration provided in geotechnical report; supplemental letter required Environmental Checklist Revisions may be required concerning: 1) cut quantities, 2) maximum existing slopes, and 3) ground water withdrawal Tree Cutting Plan Not submitted, but probably not needed Topographic Map Incomplete, topography within eastern portion of lot missing Geotechnical Report Incomplete, see following Project Plans Incomplete, see following The scope of our technical review was limited to a general check of interpretations, assumptions, and method of analysis for reasonableness and completeness. Our review does not include checking specific calculations or independent analyses. 02/12/91 EDMONO6\SM012CLLT P.O. BOX 1029 • EDMONDS. AVASHINGTON 98020 9129 • (206) 778-0907 • FAX (206) 778-6409 • • Conclusions and recommendations concerning site stability, foundations, floor slabs, drainage, and the overall approach to the proposed construction have been provided. In general, recommendations made to date are reasonable; however, there are several inconsistencies within the geotechnical report and it does not appear that all geotechnical recommendations have been incorporated into the project plans. The following is a list of questions, comments, and/or inconsistencies noted during our preliminary geotechnical review: 1. There is a set of concrete steps at the west end of the property, suggesting a former residence or structure. If available, historical information concerning this lot should be provided, particularly if a former structure was damaged or destroyed by past landslide activity. 2. Existing interceptor drain: It is our understanding that the existing interceptor drain was constructed in the early 1980s as part of the City's Meadowdale drainage improvement project. The project geotechnical report states that some ground. water was being intercepted by this drainage system (summer 1990), but that the source of the seepage was not determined. A reconnaissance by Landau Associates on January 21, 1991 confirmed flow from this drainage system into a catch basin along 75th Place. Cbnstruction details concerning this drain are not provided. Development plans call for relocation of this drain to near the eastern margin of the property at an elevation at least 10 feet higher than at present. It appears that the design engineers are assuming that all ground water is migrating atop a silt stratum and that reconstructing the drain at the proposed location will intercept this flow. Sufficient investigation to determine if this silt layer provides recharge to the western portions of the property drained by the present system has not been performed. We are concerned that, if the present drain is abandoned and the replacement drain does not intercept ground water entering the existing system, downslope properties could be negatively affected. Additional information concerning the existing system is needed. Consideration should be given to relocating the existing drain to the west of the proposed structure. A method of abandonment for this drain has also not been provided. We recommend that an abandonment plan be provided. 3. Site geology: The geologic interpretations provided by the project geotechnical engineer differ from City -accepted information provided by Roger Lowe Associates and GeoEngineers. Questions that result are: 1) why site investigations did not encounter ground water (yet a shallow onsite drainage system appears to flow on a year-round basis), and 2) what significance the 30-degree dip noted in the bottom sample of Boring 2 has (i.e., has soil at that depth been disturbed)? If an adequate response to these questions cannot be provided with existing information, piezometers and additional borings may be required. Also, the geotechnical report correctly notes that the contact of the Esparence sand and Whidbey clay is often the location of slope instability. The report states that the Whidbey clay extends up the slope to approximate Elevation 150 feet; therefore, this potential zone of instability is located a short distance above the top of the proposed soldier pile wall. This is not consistent with later comments in the report (page 21 and Figure 19) that 02/12/91 EDMONDS\SMR0124.LET 2 LANDAU ASSOCAHS. INC. indicate the slope is all Whidbey clay and which imply that the potential for instability of the steep slope on the east portion of the property is low. We recommend that this discrepancy be reviewed and addressed. 4. Topographic map: The lack of accurate topographic information along the eastern portion of the site makes it difficult to determine the final soldier pile wall height. Also, a comparison of the existing and proposed site grades to the west of the pf6posed residence indicates that several feet of yard fill will be required; however, we understand such filling is not intended. We recommend that the missing topographic information be provided, and that topography shown elsewhere on the site be verified. 5. Project plans: The project plans we reviewed are undated and have not been stamped by a licensed structural engineer (where appropriate). Also, the scale(s) for details shown on Sheet 3 are missing. It is recommended that this information be added to the final plans. 6. Pile foundation for residence: The project plans leave out significant detail concerning the pile foundation for the proposed residence. Missing information includes, but is not limited to, the size of individual piles, the size and direction of placement for reinforcing structural beams, and anticipated pile depths. In our opinion, the project plans should provide sufficient detail so that the foundation could be constructed without need for constant reference to the geotechnical report. If it is determined that the bottom sample in Boring 2 (which dips at 30 degrees) represents material displaced by landslide activity, then the geotechnical engineer's assumptions concerning the depth of the failure plane, soil pressures, length and diameter of piles, etc. may not be valid. Supplemental information concerning site geology and the impact of site geology on the proposed foundation scheme is needed. The geotechnical engineer has apparently analyzed the pile resistance to lateral loads using a technique based on beam -on -elastic foundation theory. This approach is an appropriate and accepted method when the pile is relatively long and the length is at least 4-5 times the relative stiffness of the pile. In this case, the pile's response to lateral load is primarily a function of the strength and bending properties of the pile and ultimate lateral pile capacity is the ultimate pile structural capacity. The influence of the soil is accounted for in the analysis by a soil modulus. However, the above method is not considered applicable when the pile is short and relatively stiff. When the pile length is less than 2-3 times the pile relative stiffness, the pile resistance is controlled by the strength of the soil and the ultimate lateral pile capacity is determined by the ultimate strength characteristics of the soil. The proposed piles for this project are relatively stiff and the length of embedment in competent soil is limited. In our opinion, the method of analysis used by the geotechnical engineer may not be appropriate because of the length/relative stiffness relationship. The geotechnical engineer should substantiate his selection of analysis method and address the above concerns. In addition to the method of analysis, we also question the soil modulus used. The geotechnical engineer used a modulus that increases linearly with depth rather than a constant value, which is typical for over -consolidated clay. We recommend the geotechnical engineer review this issue and substantiate the appropriateness of his selected method and input parameters or modify them accordingly. 02/12/91 EDMONDS\SMR01241Ef 3 LANDAU ASSOCIAII S, INC. The design contained in the geotechnical report apparently determines the lateral driving forces on piles beneath the house by analyzing the friction on a cone of soil adjacent to the pile (Figure 34 and p.43). This method of analysis may be appropriate for the case of soil flowing around the pile, as in the case of a flow slide. Where piles extend through a potential landslide zone and flow slide -type failures are unlikely, the method of analysis typically used by most engineers assumes lateral pressures acting on-amuch wider wedge of soil. The resulting difference in the methods of analyses produces a much higher lateral load on the pile than that assumed in the geotechnical engineer's design. It is our opinion that if a major landslide occurs at this location, the piles may be subjected to higher lateral forces than assumed in the design and the resisting capacity of the piles may be less than that assumed in the design. Based on our judgement and experience, we question whether the house would be safe from significant damage if a major landslide was to occur. However, to put this statement into context, it is our opinion that the pile design for this project using relatively strong piles is preferable over alternatives using spread footings or smaller diameter piles. Consequently, it is our opinion that the pile design for the house appears reasonable to achieve the objective of improving stability and lessening risk, but the owner and designers need to recognize that the risk of damage from slope instability has not been eliminated (subject to verification of stated geologic conditions). 7. Soldier pile wall: The topographic map implies.a steep slope immediately to the east of the soldier pile wall. Lateral soil pressures used in the design of this wall are based on horizontal ground. Further topographic information is needed to either confirm the present design assumption or to determine the actual slope and increase the lateral soil pressure accordingly. Pile design (i.e., depth of embedment, pile diameter, etc.) for the soldier pile wall is also of concern. See comments for the residence pile design (above). As for the proposed residence, details for the proposed soldier pile wall should be provided on the project plans. The transitions at both ends of the proposed soldier pile wall need additional consideration. At the south end of the wall, proposed grades (Sheet 1) will form a slope steeper than 1H:1V (horizontal:vertical). At this location, the wall must either be extended to the west or some other form of slope protection provided. At the north end of the wall, transition using a rockery is proposed. Once again, without accurate topographic information, the height of this rockery and backslope are unknown. It should be noted that if slope conditions require moving the soldier pile wall to the west, the driveway turnaround area may be negatively impacted. The text on page 40 states that the soldier pile wall is to be placed prior to excavation near the bench. We concur with this approach as a means to limit the potential for slope instability during construction. Note 4 on Figure 32 indicates that pile spacings are to be determined after excavations for the bench have been completed, which seems to be contrary to the statement in the report text. 8. Cut quantities: Excavation calculations provided on Sheet 1 of the project plans indicate that total cut quantities will be approximately 372 cubic yards. Based on our review, there appear to be several items which will add substantial excavation quantities to the noted figure. These include excavations for the detention pipe, grade beams and pile 02/12/91 EDM0NDS\S11R0124.LEr 4 LANDAU ASSOCIATES. INC. caps, south side of the proposed dwelling, and marginal areas outside of the presently shown cut -calculation areas. In our estimation, these excavations will add several hundred cubic yards of excavation, putting the final total well over SW cubic yards. We recommend that cut and fill quantities be recalculated to determine if a conditional use permit is needed. City memo (dated August 14, 1990) can be referenced for further information on this subject. -= 9. If yard grade is to be raised as shown on the project plans, up to 4 feet of fill in close proximity to the residence will be required. The type of fill, method of placement, short - and long-term effects on site stability, and potential downdrag caused by the fill should be evaluated by the project geotechnical engineer. 10. Rockery detail: The rockery details shown on Sheet 2 of the project plans are from a City of Edmonds Standard Detail. This detail differs substantially from information provided by the geotechnical engineer. Since the project geotechnical engineer has provided specific recommendations for rockeries on this project, it is recommended that the specific recommendations be used for final design (or the project geotechnical engineer should state that the City design is acceptable). 11. Slope east of the proposed residence: The landslide hazard map provided in the Roger Lowe Associates study identifies the bank above the proposed residence as having the potential for debris slides and debris avalanches. These types of landslides typically occur during wet wintertime conditions, they occur rapidly and are often responsible for significant property loss and occasional personal injury and/or death. We recommend that the design professionals involved in this project evaluate the potential for such slides, whether the proposed soldier pile wall can withstand the impact from such a landslide, and if the risk to personal property and occupants has been thoroughly explained to, and accepted by, the owner. 12. Slope erosion: Our visual reconnaissance of the hillside to the east of the proposed residence indicates that the present slope is approximately IH:1V. This is steeper than the natural angle of repose cited by the project geotechnical engineer; as a result, future slumping and gradual erosion of the bank can be expected. The City should determine if provisions for maintenance (i.e., removal of sloughed material) have been included in the submittal and if the owner is aware that such maintenance may be required. 13. Drainage: The project geotechnical engineer recommends crawl space and garage drainage, as well as perimeter drains for retaining walls. These drains are not shown on the project plans. Other drains within the building, or for perimeter grade beam are to be determined in the field. If construction is accomplished in late summer, it is probable that seasonal seepages and/or wet zones will not be encountered. For that reason, we recommend that all potential drains be shown on the project plans. Specific drain segments can then be omitted if field conditions warrant. 14. The geotechnical report states that the investigation was limited in extent, with the presumption that the project geotechnical engineer would be onsite during construction to provide pertinent and ongoing engineering recommendations. As a result, the City must, as a condition of permit issuance, require that Hemphill Consulting Engineers be hired to provide construction monitoring services. A list of construction inspections and verifications is provided on pages 66 and 67 of the geotechnical report. In addition to the items on that list, the geotechnical engineer should verify that all final slopes are 02/12/91 EDM0NDS\SMM24.LEr cj LANDAU ASSOCIATES. INC. stable and that the existing drain is properly abandoned (if it is determined that such abandonment is warranted). 15. Miscellaneous Geotechnical Report Comments: A. The geotechnical report states that this site was involved in landsliding in 1945/1947. A September 23,1968 Dames and Moore report indicates that this site slid during the winter of 1955/56. B. The consistency description for several of the geologic units shown on the boring logs are not consistent with standard penetration test blow counts. If additional data is present which justifies the present consistency descriptions, that information should be provided. Otherwise, the consistency description should be consistent with blow count information. C. Figure 29 of the geotechnical report states that soil backfill under grade beams should be compacted to 90 percent maximum density in accordance with ASTM D-1557. The text of the report states that 85 percent is acceptable. D. Sheet 10 of the project plans indicates that the allowable soil bearing pressure at the site is 2,000 pounds per square foot (psf). It should be noted that this value includes dead loads, lives loads, and wind and seismic loads. In summary, we recommend that the present submittal be returned to the lead design professional to answer questions and/or clarify issues cited herein. Please do not hesitate to call if you have questions. WDE/njb No. 74-24.10 02/12/91 EDM0NDS\SMFM24.I.ET 6 Very truly yours, LANDAU ASSOCIATES, INC. By: William D. Evans, CPG Senior Geologist reviewed by: Dennis R. Stettler, P.E. LANDAU ASSOCINFES. INC. ATTACHMENT 1 • Sheets 1-10 of the Project Plans, Design Works Construction, undated. • Unnumbered drawing containing the Vicinity Map, Landslide Hazard Map, and Topographic Survey; Drawing assembled by Design Works Construction, undated; Topographic survey prepared by Darrell Ford and Associates, Edmonds, WA, June 19, 1990. • Geotechnical Engineering Report, Hemphill Consulting Engineers, December 10, 1990. • Standard Drainage Plan Detention System, City of Edmonds, page 9 of 9, November 6, 1990. • Environmental Checklist, signed by David Spiro, October 28, 1990. • Owner's Liability Statement, signed by David and Joanne Spiro, November S, 1990. 02/12/91 EDMONDS\SPIR0124.LET STREET FILE To: The City of Edmonds, Washington From: David and Joanne Spiro Re: Home to be built at 15631 75th Place West Owners' Liability Statement We wish to state that to our knowledge all information included in this application is accurate. We have hired a professional architect, a geotechnical engineer, and a structural engineer who have come to the conclusions set forth in our application. While the City of Edmonds and its staff have helped us to be aware of the potential risk of building on our lot, the means of minimizing that risk have been developed entirely by our professionals, and we therefore would not hold the city liable should our project fail to meet our expectations. i David Spiro Date Joanne Spiro y(gazyt, tt b Date It 151q0 *STREET FILE 40 To: Bob A.lbert City Engineer NOV 13 1990 City of. Edmonds PERMIT COUNTER From: David and Joanne Spiro Re: Request for sidewalk waiver 15631 75th Place West Application file number 247 We hereby request that the requirement to construct a curb and sidewalk on the westerly side of our property be waived or postponed for the following reasons: 1. Our property rises approximately 6 feet directly from 75th Place West, making it very difficult to construct the required sidewalk. 2. A ten foot right-of-way has been granted to the City of Edmonds for future road development. This would indicate that in the future the road and thus the sidewalk would be moved to another location and elevation, thus destroying any present construction. 3. No other curbs and sidewalks are presently in place along 75th Place West; therefore, our sidewalk would have nothing to link up to, either in direction or elevation. We are submitting a covenant to participate in/waive right to protest this LID along with this letter, and our plans are on file with the city. Please let us know if you should need any other information. Thank you for ,your consideration, m� 0 If UTA) �c �� [, Lz. L• November t:19 ?0 STREET FILE ROJECT REVIEW CHECKLIS ,- PROJECT NAME: 6Fly SItr XD o%-rjnrC!j! N CHECK #: 21-1;z I Fie nt- PROJECT ADDRESS: RECEIPT DATE: 1116196 REVIEWED Y: (initial/Date) PLAN. WATER COMMENTS FIRE BLDG. SEWER STREET- ENG...,:. Setbacks/Variance/Setback Adjustment Conditional Use Permit . . . . . . . . . . . . . . . . . . . . . . . . ..... ................. ............. 2 ADB Requirements .......... 3 Other Zoning Requirements ......... . . . . . . . . . . . . - - ------ -- - - - - - - - 4 Underground Wiring Required -- - --------- 5 Lot Slope 15% o G . . . . . . . . . . . 6 SEPA Environmental Checklist/Hydraulics Permit Permit .7- Tree Cutting Plan 8 Plat/Subdivision Requirements Legal Description Verification Quit Claim��et �Dedicatip—rik . . . . . . . . . . . . . . . . . . 10. . . . . . . . . . . . . . . . . . . . . . . . . 3- 1A Easements <11u-bl-iq/Private_,e7&�f&g; 2 Engineering Storm Drain Review Fee '-3n j..m. -g Engineering AM Inspection Fee . . . . . ..... , ................. 14-. �,r 45 Drainage Plan (On -Site) t"7 3-Z9 15 Setback - Top of Bank, Stream, Water Courses . . . . . . . . . . . . . . . . . . . . . . .............. Setback -Storm Drain Line 1J. 9,p h4,,w Open Ditch - Existing VON. .1 - - - - - - - - - - - - - --17, -18 Culvert Required NIX Culvert Size . . . . . . . Shoulder Drainage/Shale Open Runoff 21 Catch Basin Required A.X> ----- --- ----- ..... . . . . . . . . . . . . . ............ 2 Driveway Slope,& Vehicle.Access AV ........................ .......... Sidewalk Re uired-Y65 Curb & Gutter Required 7,b r Cox ---.94- .3 Curb Cut For Driveway. Required 49 Street Paving Required - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - �27 Right -Of -Way Construction Permit Required %U Street Name Sign Required "Lfi�. 8 . . . . . . . . . . . - .... - Other Signing Required /jo ....................... .............. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ::ao Bond Required For Public Improvements Alo FEMA Map Check/Water Table Side Sewer Availability ----------------------- . ... ............... Calculate Sewer Connection Fee If No LID #,-/d Create Street File &-/9 35-- Existing Water Main Size. y "D-1:7 . . ... . . - - - - - - - - --- -- ------ - ............ Water Meter Size X ... ...... ... .. . Service Line Size u1b ........ ..... Q.. Water Meter Charge Re uire w ........ . . . . . . . ... ........ Hydrant Required Hydrant Size Existing -41- Fire Line Charge Required - Sprinkler Z42 I Street Cut ............... . . .. ...... -7 aou A31 Miscellaneous 04 &UP Ag U771177,T5 f 3-/9 4 Aij PLANNING IN ENG)NEERING PUBLI,6 WORKS. S3TREET FILE PE �,`I REQUIREMENTS TO: Permit Coordinator Bu� i `sionn 11 FROM: Lyle Chrisman, Engineering Inspector OWNER: �v -7 py PLAN CK # L"' t ADDRESS: t T v DATE:_ 15 HAR9 After review of the subject permit application, the following requirements. mustbe met. 1. Construction hours are: WEEKDAYS .......... 7:00 A.M.-10:00 P.M. WEEKENDS/HOLIDAYS ..... 10:00 A.M.-6:00 P.M. 2. A separate RIGHT-OF-WAY- Construction Permit is required for all work on Publicproperty. (ECDC 18.60) 3. Truck haul route plan must be submitted and approved prior to permit issuance. 4. Builder/Owner is responsible for containing all temporary runoff and erosion control on site. (ECDC 18.30.030d) 5. NO WORK SHALL BE DONE WITHIN 15 FEET OF STREAMS OR 10 FEET FROM ANY CLOSED DRAINAGE FACIL- ITY. BUILDER/OWNER IS REPSONSIBLE FOR IDENTIFYING CONDITIONS ON THE DRAWING. (ECDC 18.30.50G) 6. FILTER FABRIC FENCE SHALL BE INSTALLED AND INSPECTED PRIOR TO CLEARING AND CONSTRUCTION. (ECDC 18.30) 7. INSPECTIONS ARE REQUIRED ON STORM DRAINAGE SYSTEMS, TIGHTLINES, FOUNDATION DRAINS, AND CATCH BASIN INSTALLATION. INSPECTIONS ARE REQUIRED PRIOR TO BACKFILLING. (ECDC 18.30) 8. Repair or replace all defective existing curb, gutter, and sidewalk adjacent to the property. If an intersection is involved a handicap ramp may be required. Contractor shall meet with the City Engineering Staff to determine the extent of repair prior to issuance of the permit. (ECDC 18.90) 9. Driveway slope sh 1 t exceed 14 % without a waiver. Every attempt should be made to keep the slope below 14%. Waiver granted to 7%. (ECDC 18.80.060D) 10. Driveways must be paved from property line to City RIGHT-OF-WAY. A separate perimit is required. (ECDC 18.80.060C) 11. INSPECTIONS ARE REQUIRED ON DRIVEWAYS AND SIDEWALKS PRIOR TO AND AFTER POURING. (ECDC 18.30) 12. No burning of construction refuse without a permit from the Fire Department. 13. Connection to City water system is required. There is a separate charge for the water meter. (ECDC 7.30) 14. A back water valve is required if downstairs plumbing is below the elevation of upstream manhole. (ECDC 7.20) 15. Water and sewer mainlines should be separated by 10 feet minimum. (ECDC 18.10) 16. Connect' the City sanitary system is required. A separate permit i r u� LID# b Fees paid: Yes No Charge (ECDC 18.10) 17. Underground wiring is required on all new construction; and for additions, alterations, and repairs that exceed 50 % of the total assessed value of the structure. (ECDC 18.05.010) 18. A FINAL ENGINEERING INSPECTION IS REQUIRED PRIOR TO THE BUILDING DIVISION GRANTING OCCU- PANCY OF THE BUILDING OR STRUCTURE. (ECDC 18.90) 19. 00 1 M-I l' lb r6 e C; ; /lU e U- � l Cj,0 GA'50- 40rl— A stop goAzpa ZI. htz>� l��,a� �rJ ✓> STREET FILE STREE?FILE To: Bob Alberts City Iingineer City of: Edmonds From: David and Joanne Spiro Re: Request for driveway slope waiver 15631 75th Place West .Application file number 247 0 ,R�� Nov PoMll COUNTER We hereby request an exception to the allowable maximum driveway slope. The total average slope of our driveway is approximately 13.3%, but in an effort to make the approach off. of 75th Place West as well as the landing: entry to the garage a more gentle slope, we felt it was necessary to increase the middle portion of the driveway to a greater slope. Beginning at 75th Placer -West, the approach goes from a 6/ to �a�/= rthen to=a�-1-- , =th•e•n to�20/' for the middle portion of the driveway. From the middle portion, the slope then eradiates to the upper landing area where the slope is Because of the existing contours and the placement of the garage, we feel this driveway design is the only economically and environmentally reasonable alternative. The driveway begins from the road at such a gentle slope, we feel that it will not present a traffic, pedestrian, bicycle or safety hazard and that the public health, safety and general welfare will not be adversely affected. Our plans are on file with the city. Please let us know if you should need any other information. Thank you for your consideration, �L•u November 10, 1990 ROM•Z� .. , 1�Tii.?"14�.� ..�^�I�:.S,7'yi. BFi iNil+.'fl+7W'&.y�,,...Y,.i�• M.M.jq`ol�A'rhtiV�""'F•n*'ti'In'�vi•'•.Sr`vi.9r.o• 5.4 •w'•.'- -'- �v,.; "• -..i .. v.:. . Y •: is t�Y OF EDMONDSgermit No.0 ` COMMUNITY SERVICES D �KT FILLFecit'vi, RIGHT-OF-WAY' CONSTRUCTION PERMIT Issue•Date --JUL 2'57'iii a5—� A. • Owner: it10I21LS COtuSi. N me 7-1)3 15TN ptv NC Mailing Address SSA-'rTL� W A q �S 115 City State Zip ictor: Pun Name Mailing Address ns W R !9 Q0 ZL. City State Zip V" VA:r M R RT 1'1 State License Number Telephone Number C. • Address or Vicinity of Construction: 1 Se3 1 % STH P L w Type of Work to be Done: t Q46TPrLL... uWML- C240ymb FALL I Tt&S OW E x 1ST1 N & POLE, TRA_-NLN POP -TN IN 9-1W 1021 TO PROP to?-06Z tNsTPt.L P&DISTAL . RR+✓6-to9. a 94 IN W I -r tt (,.IL ASS D. • Work in Connection With: ❑ Sub or Plat G091`ngle Family ❑ City Projects ❑ Commercial ❑ Multifamily ❑ Utility E. • Pavement Cut: ❑ Y ®''lv, F. • Size of Cut: X APPLICANT TO READ AND SIGN INDEMNITY: Applicant understands and by his signature to this application, agrees to hold the. City of Edmonds Harmless from any injuries, damages,, or claims of any kind or -description whatsoever, forseen or unforseen, that may, be made against the City of Edmonds, or any of its departments or employees, including or not limited to the defense-,% of any legal proceedings including defense costs, court I.costs; and attorney fees by reason of granting this permit. THE -CONTRACTOR IS RESPONSIBLE FOR WOkI{ ANSHI�P AND MPIARIALS FOR A PERIOD OF ONE YEAR FOLLOWING THE FINAL INSPECTION AND ACCEPTANCE OF THE WORK. Estimated restoration fees will be held until the final street patch is completed by City forces, at which time a debit or credit will be processed for issuance to the applicant. • A 24 hour notice is required for inspection; Please call Engineeri g: 771-3202 • Work is to be inspected during progress. and 't-,complet}on•.�,+� • Restoration to be in accordance with City Co�ae�� 1 I • Street to be kept clean at all times. • Traffic Control to be in accordance with City regulations. • All street -cut ditches must be patched with asphalt or City approved material prior to end of working day; NO EXCEPTIONS. 71.K I understand the above and that this permit must be available at the job site for inspection purposes at all times. Signature: Date: �Z---`� Owner or Contractor This Permit Must be Posted at the Job Site For Inspection Purposes Call DIAL -A -DIG Prior to Beginning Work APPROVED BY: Ate PERMIT FEE: 5D. 80 fhc �,te 0 a Z Time Authorized: Void after days. Restoration Fee: O W Special Conditions: Receipt No.: Fund 111 Fee: Street Cut Dimensions: X = $ U RELEASED BYNk O� L�r`� ' Date �7 a 5 INSPECTED BY �Y�� Date L� a O w NO WORK TO BEGIN PRIOR TO PERMIT ISSUANCE FIELD INSPECTION NOR (Fuln?l*l I Route copy to Street De�.j, Comments: Diagram: CONTRACTOR CALLED FOR INSPECTION 0 YES 0 NO Partial Work Inspection by P. W.: Work Disapproved By: Date: FINAL APPROVAL BY: Date: Eng. Div. J ± // � P dj� . ... / ; \7-2 ~ Z }3\?}7 o OL a - ..� °-2't ) }® 7 i ID4 � N� ..`�00 @ 0a° � �\\\\� (\ } �- f� [ \\ )§ \/\ /\u + ®`! 2)« ^±3 /o Ell \) Ie 3 D■ ] \ °l 00 tea= w� • • m w 0 m 00 Q 0 o N r Q } N � W > UI J Z w m > Q W z ~ 0 (n w w U) Q 0 Z Q (A J 0 in w_ 0 0 U) N InW Z 0 0 w a C Q � 0 > Z Q w :)? w l7 0 N a Z Z w O 0 w U F w d inZ Z Z 0 W O w Y 0 O Q 7 I U1 W Q Z Q w UO U) 0 Z 0 w w QLL w ¢ 0 Z 0 m J Z x Q w w Z U Z O F Q Q !N 0 NN� UJ z m J tL N (On • • • H E M P H- I. L L Ct7NSUL—ItNG ENGINEERS STREETTILE - PL GEOTECHNICAL ENGINEERING FOR THE PROPOSED Mtn f c� SPIRO RESIDENCE TO BE LOCATED AT 15631 75th PLACE WEST EDMONDS, WASHINGTON ^S; 10 DECEMBER, 1990 921 109TH AVENUE S. E. • BELLEVUE, WA. 9B004 • 453 4760 TABLE of CONTENTS INTRODUCTION page AUTHORIZATION for GEOTECHNICAL ENGINEERING . . . . 1 PURPOSE of GEOTECHNICAL ENGINEERING . . . . 1. PURPOSE of GEOTECH141CAL INVESTIGATION . . . . . 1 PURPOSE of GEOTECHNICAL REPORT . . . . . . . . 1 DESCRIPTION of PROJECT . . . . . . . . . . . . . 3 RATIONALE for INVESTIGATION and RECOMMENDATIONS . . . 4 ASSUMPTIONS for GEOTECHNICAL ENGINEERING . . . . . . 5 LIMITATIONS of INVESTIGATION and REPORT . . . . . 5 GEOTECHNICAL INFORMATION for the CONTRACTOR. . . . . 6 SITE INVESTIGATION SURFACE DESCRIPT!ON . . . . . . . . . . . . 8 SUBSURFACE INVESTIGATION . . . . . . . . . . 8 RATIONALE for INVESTIGATION . . . . . . ... . . 8 METHODS of INVESTIGATION . . . . . . . . . . . 9 HISTORY of SITI= . . . . . . . . . . . . . . . 9 GEOLOGICAL RESEARCH . . . . . . . . . . . . 9 VISUAL OBSERVATIONS . . . . . . . . . . . . 10 FIELD TESTS . . . . . . . . . . . . . . . . 11 GROUNDWATER OBSERVATIONS . . . . . . . . . 15 SITE STABILITY INVESTIGATION . . . . . . . . . 17 SOIL DESCRIPTIONS . . . . . . . . . . . . . . . 17 HOW PHYSICAL PROPER T iES of SOILS DETERMINED . . . 17 DESCRIPTION of UNDISTURBED NATURAL SOILS . . . . . 18 CONCLUSIONS . . . . . . . . . . . . . . . . . 21 ENGINEEITNC STUDIES and RECOMMENDATIONS RATIONALE for RECOMMENDATIONS . . . . SEISMIC STUDIES . . . . . . . . . . . . . . STABILITY ST1:CIES . . . . . . . . . . . . . SITE PREPARATION . . . . . CLEARING, and STRIPPING . . . . . . . . . . PROOF lROi_; ,N'j . . PURPOSE of PROOF ROLLING .. . . . . . . DESCRIPTION of PROOF ROLLING . . . PLACEMENT of WORKING SURFACE . . GENERAL SITE EXCAVATING . . . . . . . . . DESCRIP PON of EXCAVATING . . . . . . . ALLOWABLE SLOPES for SIDES of EXCAVATIONS: GENERAL SITE FILLING . . . . . . . DESCRIPTION of FILLING . . . . . . . . DESCRIPTION of STRUCTURAL FILL . . . . . PREPARATION of EXISTING GROUND SURFACE 23 23 26 28 28 2.9 29 29 29 29 30 30 31 31 31 32 page PLACEMENT of STRUCTURAL FILL on SOFT SOILS . . . 32 CONTROL of COMPACTION of STRUCTURAL FILL 32 DENSITY REQUIREMENTS of STRUCTURAL FILL . 35 COMPACTION of BACKFILL ADJACENT to STRUCTURES 35 DESIGN PARAMETERS for TEMPORARY FOUNDATIONS . . . . 36 PREPARATION of EXISTING SOILS . . . . . . . . . 36 APPROVED BEARING SOILS . . . . . ... . . 36 BEARING CAPACITY of APPROVED SOILS 36 SETTLEMENT ESTIMATIONS . . . . . . . . . . . 37 SETTLEMENT of GRADE BEAMS . . . . . . . . 37 SETTLEMENT of GARAGE SLAB.. . . . . . 37 SETTLEMENT of BACK PORCH . . . . . . . . 38 SETTLEMENT of DECK & STAIRS . . . . . . . . 38 DESIGN and PLACEMENT of SPREAD FOOTINGS . . . . . . 39 DESIGN of SPREAD FOOTINGS . . . . . . . . . 39 OVER -EXCAVATIONS to BEARING SOILS . . . . . . . 39 MINIMUM WIDTH of FOOTINGS . . . . . . . . . 40 MINIMUM DEPTH of FOOTINGS . . . . . . 40 MINIMUM DEPTH for BEARING .. . . . . . . . 40 MINIMUM DEPTH for FROST PROTECTION . .. . . . 40 DESIGN of GRADE BEAMS . . . . . . . . . . . . 40 DESIGN of PILE FOUNDATIONS . . . . . . . . . . . . 40 DESCRIPTION of PILES . . . . . .. . . . . . . . 40 MINIMUM DEPTH of PILES 42 MINIMUM DEPTH of PILES for BEARING . . . . 42 MINIMUM DEPTH for STABILITY on SLOPES . . . . 42 END BEARING for PILES ... . . . . . . . . . . . 42 SIDE FRICTION for PILES . . . . . . . . . . . 42 DESIGN of INDIVIDUAL PILES . . . . . . . . . . . 44 DESIGN of RETAINING WALL PILES . . . . . . . 46 DESIGN of SOLDIER PILE WALL . . . . . . . . . . . . 49 CONCRETE FLOOR SLABS . . . . . . . . . . . . . 51 DESCRIPTION of CAPILLARY WATER . . . . . . . . 51 PREPARATION of BASE COURSE for FLOOR SLAB . . . . 51 PROTECTION of FLOOR SLAB from CAPILLARY WATER . . . 51 DRAINAGE of SLAB BASE COURSE . . . . . . . . 51 ROCKERY . . . . . . . . . . . . . . . . . 52 DRAINAGE . . . . . ... . . . . . . . . . . . 59 EXISTING INTERCEPTOR"DRAIN .. . . . . . . 59 NEW SUBSURFACE DRAINAGE . . . . . . . . 59 SITE SURFACE DRAINAGE . . . . . . . . . . . 59 SLAB DRAINAGE . . . . . . ... . . . . . . 61 CRAWL SPACE DRAINAGE. . . . . . . 62 GRADE BEAM DRAINAGE . . . . . . . . . 63 RETAINING WALL DRAINAGE . . .. . .. . . . . . . 63 PAVING . . . . . . . . . ... . . . . . . 64 FUTURE STUDIES and RECOMMENDATIONS DESIGN REVIEW. . . . . . . . . . . 66 CONSTRUCTION INSPECTIONS and VERIFICATIONS . . . . . 66 LIST of FIGURES 'IGURE TITLE or DESCRIPTION PAGE FIGURE TITLE or DESCRIPTION PAGE 1 LOCATION of PROJECT . . . . . . . . . 1 28 EXCAVATED SOILS . . . . . . . . . . . 30 2 VIEW of PROPOSED HOUSE . . . . . . . 2 29 OVER -EXCAVATIONS . . . . . . . . . . 36 3 PLAN of PROJECT . . . . . . . . 3 30 SETTLEMENT VS LOADS, ETC. 38 4 SECTION of PROJECT. . . . . . . . . . 4 31 LOCATIONS of DECK FOOTINGS . . . . . 39 5 VIEWS of HOUSE . . . . . . . . . . . 5 32 LOCATIONS of PILES . . . . . . . . . . 40 6 VIEWS of HOUSE . . . . . . . . . . . 6 33 DESCRIPTION of RESISTING SOILS . . . . 42 7 TOPOGRAPHIC PLAN of SITE . . . . . . . 8 34 LATERAL FORCES on INDIVIDUAL PILES, 43 8 GEOLOGIC MAP of VICINITY . . . . . . . 9 35 SECTION of INDIVIDUAL PILES . . . . . . 44 9 LOCATIONS of FIELD TESTS . . . . . . . 11 36 DESIGN PARAMETERS for INDIVIDUAL PILES 45 10 LOGS of TEST PITS . . . . . . . . . . . 11 37 DESIGN of INDIVIDUAL PILES . . . . . . . 45 11 DRILLING EQUIPMENT . . . . . . . . . 12 38 RETAINING WALL PILE DESIGN PARAMETERS 46 12 LOG of BORING 1 . ... . . . . .. . . . 13 39 DESIGN of RETAINING WALL PILES . . . . 47 13 LOG of BORING 2 . . . . . . . . . . . 13 40 'P-SLIDE FORCES on RETAINING WALL PILES 48 14 EQUIPMENT for SPT . . . . . . . . . . 14 41 "'SECTION of SOLDIER PILE WALL 49 15 SPLIT SPOON SAMPLER . . . . . . . . 14 42 CONSTRUCTION of SOLDIER PILE WALL 49 16 INTERCEPTOR DRAINAGE . . . . . . . . 15 43 SOLDIER PILE DESIGN PARAMETERS 50 17 CAPILLARITY ... 16 44 DESIGN of SOLDIER PILE WALL . . . 50 18 SECTION of SLOPE to RAILROAD . . . . . 17 45 CAPILLARY BREAK . . . . . . . . . 51 19 ESTIMATED GEOLOGIC SECTION 21 46 LOCATION of ROCKERY . . . . . . . . . 52 20 MAP of SEISMIC ZONES . . . . . . . . . 23 47 EXAMPLE ROCKERY . . . . . . . . . . 53 21 DESCRIPTIONS of SEISMIC INTENSITIES 24 48 DESIGN VS CONSTRUCTED ROCKERY 54 22 LIQUEFACTION . . . . . . . . . . 25 49 ROCKERY DESIGN PARAMETERS 54 23 SECTION for STABILITY STUDIES . . . . . -26 SO ROCKERY DIMENSIONS for CONSTRUCTION 56 24 EXAMPLE STABILITY CALCS . . . . . . . 27 51 '`" LOCATION of NEW INTERCEPTOR DRAIN . 59 25 STABILITY CALCULATIONS PARAMETERS. 27 52 SOLDIER PILE DRAINAGE . . . . . . 60 26 STABILITY CALCS . . . . . . . . . 28 53 PROPOSED STORMWATER DETENTION 60 27 WORKING SURFACE . . . . . . . . . . 29 54 DRAINAGE OPTIONS" . . . . . . . . . 64 FIGURE 1 LOCATION of PROJECT �->TRo �, v '"V"'� PL SA 148TH 149TH NUHMA SOUND �T FISHER <IR =;t �'o > M . 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ST W> 18 ST PL SW Q I- � -P SW fT- L Q 181 ST PL W �8 a DEPT 181 S l -� 181 �S� S 82ND �� 3 82ND ST roA� 56�� FAD OF _ a QPST 182 S�/ �. LICENSING >% 183RD PL �� =1183RISW 83R 182 �p> S ~ I PL SW w3 tir vV a ¢ 1 RO Q / Q !G 1'd h8�►SN 183RD 0303 3 Q� v Z / STSW1Sj g ii LL _ > 184TH ST SW CL C 185TH.I , Q i F 3 185TH in ST S Q x SNAKE ti > a 3 = y ° l �' 185THt PL 1assT RpTRAI( . S'T T/yQ. 3'a f" 3 = g6TH ST SW I Z a W 3 x �$ = 186THN/' SW H o��p t x� 1 7TH i L Q —LF --187�i� P6 SW A !o— �j _j cD Z _j PL SW cep — -- pS — >aa - - —� a - -- - 188TH- SPIRO RESIDENCE INTRODUCTION AUTHORIZATION for GEOTECHNICAL ENGINEERING page 1 of 67 pages In a contract dated 19 April, 1990, David Spiro [CLIENT) authorized HEMPHILL CONSULTING ENGINEERS [HEMPHILL] to conduct geotechnical engineering for the proposed [PROJECT] .to be located at 15631 75th Place West, Edmonds, as shown approximately in Figure 1. PURPOSE of GEOTECHNICAL ENGINEERING The purpose of the geotechnical engineering was to conduct a geotechnical investigation at the site of the proposed PROJECT, and to prepare a geotechnical report. PURPOSE of GEOTECHNICAL INVESTIGATION The purpose of the geotechnical investigation at the site of the proposed PROJECT was to determine the stability of that portion of the site that would affect the proposed structure, to, determine the soil conditions for foundations, slabs, and paving, and to determine the groundwater - conditions for drainage. PURPOSE of GEOTECHNICAL REPORT This report was prepared for the following purposes: a. To present information to the. CLIENT to understand the geotechnical portions of. the PROJECT. b. To present the results of the geotechnical investigation and testing, and geotechnical designs of rockeries and piles. c. To present recommendations for the CLIENT, the architect, and the structural "engineer 'to design the foundations, floor slabs, drainage, retaining systems, and paving, and to prepare specifications for construction control and verifications. FIGURE 2 PROPOSED HOUSE --V SPIRO RESIDENCE page 2 of 67 pages d. To present some limited information to the contractor to determine some anticipated site conditions, to present some construction requirements and possible changes . to be determined at the time of construction, and to help the contractor establish. some construction procedures. e. To aid the Building Depart m- ent to establish an inspection program for the geotechnical portions of the PROJECT. rl� � FIGURE 3 PLAN of PROJECT iiilf,4M Nlf Adla SCALE 1" - 20' •Q lelc oil nr _ _ � � ����� VOA �� _ �_ � T ���� r.�•^'— � ���QC HOUSE GARAGE •• r OLL lcA / d Joe P F9 1 �b SPIRO RESIDENCE DESCRIPTION of PROJECT page 3 of 67 pages The PROJECT will be a single family dwelling located on the site as shown in Figure 3. The house will be a 3 story wood frame structure with an attached garage at the rear. Figure 4 on the next page shows the project in section. The house will be supported by grade beams that span between lateral resisting piles: The lateral resisting piles will be designed to resist lateral movement of potentially unstable soils under portions of the site. The garage floor will be a'structural slab that spans between grade beams. Part of the garage structural slab will be located over a crawl space. The lower floor of the house will be supported by wood joists over crawl spaces. The wood joists will" span between grade beams. A portion of the northeast corner of the house adjacent to the driveway will be designed as a soldier pile system to support a retaining wall on piles. The retaining walls will support the driveway and the back porch. A soldier pile retaining wall will be placed at the rear yard to support the excavated portion of the rear slope. A second story deck at the front of the house will. be supported by spread footings. The deck will be designed to allow for some settlement and lateral movement. A spiral stair from the deck to the ground surface will be placed on a spread footing. A rockery, shown in plan in Figure 3, will support a portion of the driveway adjacent to the house. The back porch will be supported by structural fill soils that will be supported by the retaining foundation wall. The drainage for the rear soldier pile wall will be constructed to intercept any groundwater from the slope and conduct it to the existing 'interceptor system. The rear portion of the existing interceptor system will be removed and a new system will be constructed behind the soldier pile wall. I-H E M P H I L L 00 = Lo i~ a 0 0 LLI U) U. i� mlw�Imll U) W rom ; 'Qv w g J CL O Z ` a O i w Q I i U) J a n j w V) 1 N o _ . w F _ rI > W Co w D C) LL 1 i 5 6-P.10. 91S��DT=104:4 page 4 of 67 pages RATIONALE for INVESTIGATION and RECOMMENDATIONS The request by the CLIENT for HEMPHILL to conduct geotechnical engineering, regardless of any specified charges, imposes the obligations implied by state and local building codes, and the State of Washington Registration Act for Professional Engineers, that all construction endeavors within the state be designed and constructed in such a manner as to protect the lives, health, and property of the public; therefore HEMPHILL is obligated to investigate and make recommendations concerning all phases of construction that would affect or be affected by soils and foundations, including groundwater and drainage. In accordance with those obligations, the extent of the geotechnical studies and recommendations, including the recommended future studies to be conducted at the time of construction, have exceeded the generally accepted minimum standards to mitigate jeopardy to the lives and health of the public. The extent of the geotechnical investigation, including the subsurface explorations, any testing program, and engineering studies, have been modified in accordance with recommendations by HEMPHILL, and.'.. - approved by the CLIENT, to reduce costs; therefore, in conjunction with that modified geotechnical investigation, to minimize possible property damage, the recommendations in this report include appropriate safety factors that correspond with the extent of that investigation, based on the requirement . that the presumed. subsurface conditions will be verified by HEMPHILL.after the true conditions have been revealed by the excavations. NOTE: 'Presumed subsurface conditions' are assumed to be accurate based on the evidence that has been observed by visual examination, geologic research, and field testing, but, because of the nature of subsurface conditions, regardless of the extent of the investigation, the apparently obvious conditions are not always true, and the geotechnical engineer must always accept the evidence. with some suspicion, and never be satisfied that the presumed conditions are accurate until.those conditions have been verified by complete exposure and testing at the time of construction. The geotechnical engineer must present design and construction recommendations that are as realistic as possible without excessive costs for the investigation and design, but that will- also not require extensive_ design changes if the soil and groundwater conditions, are not as anticipated. FIGURE 5 VIEWS of HOUSE VIEW from NORTH SPIRO RESIDENCE page 5 of 67 pages ASSUMPTIONS for GEOTECHNICAL ENGINEERING The analyses, conclusions, and recommendations presented in this report are based on the following assumptions: A. That drawings and data furnished to HEMPHILL by the CLIENT are complete and correct. B. That the final plans and specifications will correctly include all the appropriate recommendations presented by HEMPHILL in this report. C. That other engineering that affects foundations, such as structural and mechanical, is correct, and correctly implements the geotechnical recommendations. D. That the proposed structure -will be constructed in accordance with the plans and specifications, and any recommendations by HEMPHILL at the time of construction. E. That site conditions will not change due to unanticipated natural causes or construction operations at or adjacent to the site. F. That the subsurface investigation revealed conditions that are representative of subsurface" conditions throughout the site. G. That data from visual observations and soil tests conducted: in the. field correctly exposed all the critical physical properties of the soils, and that those tests closely represent other soils that appear to be similar. H. That the assumed conditions presented in this report will be verified by HEMPHILL after the excavations have revealed the true nature of all the subsurface soils. 1. That. changes recommended by HEMPHILL at the time of construction will be correctly implemented. LIMITATIONS of GEOTECHNICAL INVESTIGATIONand REPORT A. This geotechnical report is intended only for the use of the CLIENT as an aid to -design and construct the specific PROJECT, and in the specific location, as described. in this report. This report may not be used by any other person or firm, or, for any other project, or for any other location on the described property. HEMPHILL FIGURE 6 VIEWS of HOUSE VIEW from WEST T i ru 00, t?1 C' t - •---r h� VIEW from EAST SPIRO RESIDENCE page 6 of 67 pages B. The analyses, conclusions, and recommendations contained in this report were determined from presumptive soil values based on probing, penetration tests, and visual classifications conducted at the site and adjacent areas. The extent of the subsurface investigation was in accordance with recommendations by HEMPHILL, and approved by the CLIENT, to limit the cost of the geotechnical investigation in favor of verification of .the presumptive soil values, and control of materials and construction methods, at the time of construction. C. The recommendations presented in this report are based on the requirement that the presumed subsurface conditions, and the presumptive soil. properties, will be verified by HEMPHILL after the true nature of all the soils and the groundwater have been revealed during the excavating process. D. Some of the subsurface data presented in this report contains presumed information that is satisfactory for design purposes, but is not necessarily factual.data throughout the entire vicinity of the proposed project, therefore the subsurface and testing data should not be made available to prospective contractors for bidding purposes, or to the contractor for construction purposes. E. The recommendations in this report present options. for design purposes that could be misleading to a prospective contractor. Only, the final accepted options should be made available to the contractor so that rejected options are not inadvertently included into the construction. Also included in. the recommendations are construction options that should only be determined or approved by HEMPHILL at the time of construction. GEOTECHNICAL INFORMATION-forthe.CONTRACTOR REVIEW of the GEOTECHNICALREPORT by the CONTRACTOR The contractor; and any prospective contractors_bidding on the PROJECT, should Be made aware that some of the subsurface conditions in the vicinity. of the PROJECT were presumed, and that those presumed conditions were sufficient to prepare this report, but, are not necessarily accurate throughout the entire vicinity of the PROJECT, and that the presumed conditions will be verified by HEMPHILL at the time.of construction and that any adjustments of foundations and drainage, or any other changes determined: 'by HEMPHILL to be necessary to achieve a safe, properly functioning, or less costly. structure, will be made at.that-time. SPIRO RESIDENCE page 7 of 67 pages The contractor may review this report to become familiar with the soil conditions that are anticipated by HEMPHILL, and to also become familiar with some possible methods, procedures, and options recommended by HEMPHILL The contractor should be aware that some design options presented in this report might not have been appropriate for the final design of the project, and might have been rejected by the design team and/or the building department. This report is not intended to be included as part of the plans and specifications, except those sections specifically referred to by the design team, but is intended to present information only. OPTIONS for the CONTRACTOR As described in this report, the contractor might have options for foundation and drainage design, construction -methods, and materials. Any options must be approved by HEMPHILL prior to the preparation and/or placement. GEOTECHNICAL INSPECTIONS The plans and specifications should include any requirements for the contractor to inform.. HEMPHILL:-to inspect or verify conditions at the time of construction, and to correctly implement any changes recommended by HEMPHILL. The contractor.must understand that if special inspection is required by the building department, or by the owner, that verifications of existing conditions, and of construction,methods and results, and.of approvals of materials, becomes the absolute responsibility of HEMPHILL Inspections and testing must be conducted prior to the placement and/or cover of .conditions and materials, and 'HEMPHILL will not approve conditions and materials that have not been properly observed and/or tested. If the required inspections and testing are not conducted because of the contractor's failure to request inspections. and testing at the proper time, then the requirement of more sophisticated testing, or of excavating to expose the required materials and/or construction, could be very costly. The contractor should communicate with HEMPHILL prior to the start of construction to clarify the inspection requirements, and to discuss any -options for construction procedures and materials. - - HEM PH ILL FIGURE 7 TOPOGRAPHIC PLAN of SITE - �l/If,4DDif�D,4lf f�Dvp 10 o\ siGi�r roE I \, k I 12�4 I Ila rl -- — ?2 ee 10 �.�\ \ \ \\\\'\ `,` I `.\, i �i yam•/ i�,i� ??�f � .. Ste! � ., .0 • < < �i � �/yr I SPIRO RESIDENCE SITE INVESTIGATION EXISTING. SURFACE DESCRIPTION page 8 of 67 pages Figure 7 shows a topographic plan of the existing site. The contours show the Spiro property to be a gully with the head of the gully at the east side of the property. The site rises steeply 6 feet above Meadowdale Road, then is level for 80 feet, then rises 18 feet to a 25 foot bench, then rises steeply at angles ranging from 30 to 50 degrees for approximately 100 feet before the slopes become gentle. Figure 7 shows an interceptor drainage system at the toe of the lower slope that then drains to a drainage system in Meadowdale Road. ! All of the lower slope and the lower level area is grass covered. The steeper rear slope is mostly shrub covered with some.trees. SUBSURFACE INVESTIGATION RATIONALE for INVESTIGATION The request by the CLIENT for HEMPHILL CONSULTING ENGINEERS to conduct geotechnical engineering obligates HEMPHILL to investigate, and make recommendations concerning all phases of design and construction that would be affected -by .soils and foundations, including groundwater and drainage: The subsurface investigation was established in accordance with minimum standards established by, HEMPHILL, and also with generally accepted minimum standards determined by other geotechnical engineers. Those standards were derived through experience that has proven reasonably often to reveal the true subsurface conditions throughout the sites of most projects. The extent of the subsurface investigation was based on the cost limitations recommended by HEMPHILL, and approved by the' CLIENT, with the requirement that the presumed subsurface conditions would be verified by HEMPHILL after. all the true subsurface conditions have been revealed by the excavations and. drilling for cast in place piles, and that any necessary adjustments. in foundation design and/or depth of pile placement for bearing and lateral stability will be determined by HEMPHILL at that time. FIGURE 8 . GEOLOGIC MAP of VICINITY - > .,• oats t_ Old landslides ' \ \ ;N i„ Large slumps that occurred during the ablation of the Puget Lobe of the Vashon ice sheet by lowering '14 of watertable- level. Slides may have been .� _ t active since -original movement; lacks evidence « �E -- C> of recent movement• f t c jT Vashon recessional out -ash Light -brown loosely compacted sand and gravel. Dry s 1 i. gravel seeks angle or repose of 35°; wet gravel ' will stand in near -vertical cliff. Sorting varies; rticle size varies from medium sand to cobbles. Stones are usually covered with a light -brown dusty coating and are well rounded From stream ' J-g:�'1.� 6 + + a j!s 0F• ,� k 4 } ¢t 1 transportation. Contains some ice contact deposits. `F<: D. o � i' M c :f'.� t • S �? C� �i l 5 •. � � � s } •� i � � - £ \ tt I Vashon rill / t Poorly sorted, nonstratified lodgment till deposited as fS sf. /� j�. ' ground moraine. Mixture of clay, silt, sand, peb- bles, and cobbles with occasional large boulders. Appears gray to blue on fresh surface; may weather to brown or yellow. Extremely compact, will stand in near -vertical cliffs; generally looks surficial cracks or joints. - Stones are subangular to rounded. si°+ _• i yy p Some larger clasts show striations and Faceting. Vertical -faces sometimes spall off in large blocks. `� r a ' . ; a • y Some areas of Qvt are covered by o thin veneer of M f r �. loosely consolidated, nodsorted ablation till and(or) �V `� thin outwash. f ' i\ F Avis Vashon advance outwash t }) 4(t i t \ \ Fresh, light -gray, stratified, compact sand.and gravel. f sx ft : 1 ! i �> i Will stand in near -vertical cliff. Sorting varies; / ,(� 1',i�j ! 1 ( \ }) i ';. particle size caries from Fine sand to coarse pebbles. ..• f f'd� �� ��. d„y � EF s�= £ ` '`'st: £ j (s i si QE , ers Esperance Sond i' ) ♦ �, \ \_„ Thinly bedded (Frgm 2 to 6 inches), fresh, light -gray sand layersParticle size varies from medium to r _ ( ±\\ /s - course sand'(with' 10 percent pebbles); small peb- A\ = ` E bles often occupy the base of each individual bed vi �_ <y r 1 ♦ or lens. Occasional lenses of course grovel occur. Usually sloughs to angle or repose on exposed slopes. N) fi \�'iM_ 3 Whidbey Formation /// �, / / ^~ �\\\ j t • )\ cs•A £ } ; = r Generally medium -bedded (2 to A feet) sand, silt, and \ t ( } p a -A,- " ; ) } cl Color varies from light brown to r Par ticle size varies From clay to coarse sand with a few lenses of small pebbles. Sorting is generally good within each individual bed. Clay and silt „t ,a be cs tin as 2 inches. seds cNonglae}ol .fiver 0. 1 r 3 - I{ f _ , ood- lain deposits. Ma show tectonic defom=o- Fk f t „ _ } ! • r J % ( 1 i, \ ( s i�+f� -. Double Bluff Dri Ft Contains: (1) iron -oxide cemented gravel, consisting or f, £ i r { . e3 { \ i ! �' )E f small to medium pebbles well cemented in a grit .s+� !!• 3 \?') matrix: 2 Opebbly glaciolacustrine sills; and (3) t t ! l 4 rs 1 massive rill and lesser beds of surd and grovel, l) 1{ „ W-11compacted and will stend in a nearvertical i { # r. • i z; t _ 3s cliff, Pebbly -silts display desiccation cracks at A1 _ x+ ) ! a!r li / "♦ the surface. May show tectonic deformotion. `>1- �-�,5 � £ �, ji `♦.i - , it :1 SPIRO RESIDENCE page 9 of 67 pages There have been several investigations conducted in the general vicinity of this proposed project. The subsurface investigations for those projects have revealed conditions similar to the conditions at this site. Therefore, the subsurface investigations, the foundation treatments, and the results of those other projects have been studied in conjunction with this project. - METHODS of INVESTIGATION The presumed subsurface conditions at the site were determined by historical research, geologic research, shallow probing, field tests conducted at the site and adjacent areas,: and visual observations at the site and adjacent areas. HISTORICAL. RESEARCH The general area is known as the 'Meadowdale Slide Area' because of a series of slides that have; occurred in the vicinity. 'The largest recorded slide occurred in 1945 when large movements - occurred in this gully, and in the larger gully to the south.. At that time all of the homes in the vicinity were on septic systems, and all effluent and stormwater was infiltrated into the ground.. Since that .. time sewers have been installed and septic systems disconnected, and some drainage was-; installed but not under the guidance of an expert. GEOLOGIC RESEARCH Geologic research conducted by HEMPHILL and others in.the general vicinity of the site revealed that the geologic conditions at the site are fairly typical of the Puget Sound area. Figure 8 is a partial copy of one of the geologic maps of a portion of the Puget Sound area, which shows that the general vicinity of the site,is at the intersection of the Esperance Sand and the Whidbey Clay. Descriptions of the geologic symbols are also shown on Figure 8. The geologic maps do not have great accuracy, but they help to show. soil types that are probable at the site but are not always obvious, or they help :to verify that observed soils are as suspected. The significance of the geologic maps is. that they show a general trend of geologic conditions that would appear to be reasonably continuous. Geologists have determined that as the Vashon Glacier moved south during the last glacial period, it blocked off the Straits of San Juan Fuca. Storinwater runoff from the mountains, and any meltwater from the glacier, became entrapped within the Puget Sound area. Therefore the entire Puget Sound area became a large lake.. At that time PugetSound extended from the Cascade Mountains to the Olympic Mountains, with the outlet4o the ocean through the Chehalis Valley. HEMP H I LL SPIRO RESIDENCE page 10 of 67 pages Sift and clay that eroded from the glacier, and also from the Olympic and Cascade mountains, created a muddy lake. As the clay and sift settled to the bottom of the lake they created the. Whidbey Clay stratum that is approximately 80 feet thick in some places. The geologic map shows the Whidbey Clay with the symbol Qw. Some geologists believe that the Whidbey Clay is also the Lawton Clay identified south of the site. Other geologists believe that the two clays have different origins. Their. origins and differences are not important for this investigation. As the glacier moved south, its outwash deposited combinations of coarse sift, sand, and gravel on top of the Whidbey Clay. The sandy layer is named the Esperance Sand, and is 100 feet thick in some places. The geologic map shows the Esperance Sand as Qe. The glacier eventually entered the Puget Sound area and gouged out some of the presently. existing valleys, including Puget Sound, Lake Washington, and Lake Sammamish. - As he estimated 3000 to.4000 foot thick glacier -sat in the Puget Sound area,.ft plastered much of the ground surface: with. glacial till, which is composed of various combinations of clay, sift, sand, gravel,..and cobbles. That, soil,: called Vashon Till, Qt on the geologic map, ranges in thickness from 5' to 1001. , The over riding: glacier -then compressed all.. the underlying soils to -great densities by exerting stresses of approximately 200,000 psf. As the ice melted and the glacier receded, sand and gravel that had been entrapped in the ice was loosely deposited over portions of the Puget Sound area by the outwash. That soil is designated as Qvr..on the geologic.map. . VISUAL OBSERVATIONS at the SITE and VICINITY HEMPHILL has observed the Whidbey Clay from below the level of Puget Sound to elevations of approximately 1'50 feet. The. Whidbey Clay is exposed in the steep slope along the east side of the property, and north and south of the site. Overlying the Whidbey Clay is the Esperance Sand, and often at that elevation groundwater seeps from the slope, and there is often evidence of instability. The soils overlying the ;Whidbey Clay between the steep slope and Puget sound is composed of loosely deposited silt and sand with .small chunks of hard laminated clay that apparently was eroded from the steep slope. Those soils appear to be beach deposits that might have resulted from wave action, both eroding the rear: slope and depositing the soils as a beach. The water might have been trapped between the receding glacier and higher ground, or Puget Sound might have been higher at that time. The beach deposits are overlain by sift and clay in some places where the slopes are more gentle, possibly from lacustrine (lake) deposits during periods of calm water. H E M P H I LL FIGURE 9 LOCATIONS of FIELD TESTS �Iilf,4DDif�0,41f �D,�D I \ i -�0 v I i 0-14 - BORINGS w� kN .24 Nn- a- �C. TEST PITS \ I = o T � SPIRO RESIDENCE page 11 of 67 pages FIELD TESTS TEST PITS 2 test pits were conducted, located approximately as shown in Figure 9. The test pits were conducted to locate the hard clay below the loosely deposited silts and sands. HEMPHILL conducted field penetration tests within the exposed undisturbed soils in the test pits to determine the approximate strength characteristics and other properties of the potential foundation soils for the house and the proposed soldier pile retaining wall, and/or other type retaining wall to be determined after the grading has revealed the true soil conditions along the upper bench along the east side of the site. Logs of the test pits are shown in Figure 10. The logs show visual descriptions of the soils, depths of changes in the soil types, groundwater observations, and any other pertinent observations or field tests. FIGURE 10 LOGS of TEST PITS . depth TEST PIT 3 --0 ---------------- 1 MEDIUM 2 DENSEM L E G E N D 3 RUSTY ------•------ DISTINCT CHANGE BETWEEN SOIL TYPES XXXXXXXXXXXXX GRADUAL CHANGE BETWEEN SOIL TYPES 4 SILTY a=r_aaooa==x= BOTTOM of TEST PIT 5 GRAVELY ' TOP of FREE GROUNDWATER 6 SAND 7 8 HARD GRAY 9 SILT and CLAY 10 11 12 13 NOTE: 1: TEST PIT SILT AND 14 CLOSER TO 15 2. NO FREE G TEST PIT.4 ---------------- MEDIUM DENSE RUSTY SILTY GRAVELY SAND 3 ENCOUNTERED HARD GRAY CLAY AT A HIGHER LEVEL THE SLOPE RdUNOWATFR WAS FNr:r]IINTFRFn depth 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 HEMPH ILL SPIRO RESIDENCE page 12 of 67 pages TEST BORINGS A. TEST BORING LOCATIONS 2 test borings were conducted,located as shown in Figure 9. The locations were chosen to determine foundation conditions for the proposed house, and to. study, slope conditions. B. BORING EQUIPMENT The borings were conducted using a truck mounted hollow stem continuous flight auger, similar to that shown in Figure 11. FIGURE 11 li TRUCK MOUNTED AUGER C. BORING LOGS Ti?. Figures 12 and 13 on the next page show the logs of the, test borings. The, logs were. . compiled by combining the field notes of the geotechnical engineer, field test ,data, and visual class-ifications of recovered soil samples. FIGURE 12 LOG of BORING 1 PTH COLOR CONSISTENCY DESCRIPTION of SOILS MOISTURE COMMENTS GY HARD VERY FINE SANDY SILT DAMP 9000+ (FILL?) 5????????????????????????????.??????????????????????????????????????????????????????????????????????????????????? GRAY MED DENSE VERY FINE SAND & FINE SAND WET SOUPY FROM SAMPLER 0 GRAY MED DENSE VERY FINE SAND & FINE SAND WET 5000+ 5???????????????????????????????????????????????I??????????????????????????????????????????????????????????????? GRAY HARD CLAYEY SILT DAMP 9000+ 0 GRAY HARD CLAYEY SILT DAMP 9000+ 4+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ L E G E N D------ DISTINCT CHANGE in SOIL DESCRIPTION GRADUAL CHANGE in SOIL DESCRIPTION ??????????? LOCATION of CHANGE NOT ENCOUNTERED in SAMPLE * * * TOP of GROUNDWATER +t+++t+++++ BOTTOM of BORING T SPT DEPTH 18 3 F 14 8 10 13 26 18 41 23 SPIRO RESIDENCE page 13 of 67 pages FIGURE 13 LOG of BORING 2 DEPTH COLOR CONSISTENCY DESCRIPTION of SOILS MOISTURE COMMENTS SPT DEPTH BROWN LOOSE GRAVELLY SAND WET FILL 8 3 5 BROWN and 0 7 GRAY and MED DENSE SILTY FINE SAND WET CHANGE NOT LOCATED 7 8 RUST 0 9 10 BROWN & GRAY MED DENSE COARSE SILTY FINE SAND WET 4 13 15 BROWN & GRAY MED DENSE COARSE SILTY FINE GRAVELY SAND WET 14 18 20 --------------------------------------------------------------------------------------------------------------- GRAY FIRM VERY FINE SANDY SILT WET 3000+ 12 23 25 GRAY HARD SILT DAMP 9000+ 24 28 30 GRAY HARD SILT DAMP 9000+ (LAYERS DIPPED 30 DEG) 40 33 34++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++t+++++++a+++++++++++++++++++++♦++++++++++++++ L E G E N D---------- DISTINCT CHANGE in SOIL DESCRIPTION GRADUAL CHANGE in SOIL DESCRIPTION ?77?7?????? LOCATION of -CHANGE NOT ENCOUNTERED in SAMPLE • • " TOP of GROUNDWATER +++++++++++ BOTTOM of BORING HEM PHILL SPIRO RESIDENCE page 14 of 67 pages D. FIELD TESTS Standard Penetration Tests, as described by ASTM D 1586, were conducted within the test borings at the depths shown on the boring logs. FIGURE 14 STANDARD PENETRATION TEST 140 ie DRIVE WEIGHT FREE FAIL CONTINUOUS FLITE AUGER OP It CASING SPLIT TUBE.SANFLER I in UNDISTURBED SOIL `:v: ' As shown in Figure 14, the Standard Penetration Test is conducted by dropping a hammer weighing 140 pounds a distance of 30 inches to drive a split spoon sampler into the soils below the auger. The number of blows from the hammer required to drive the split. spoon sampler 12 inches into the undisturbed soils is called. the Standard . Penetration Test. FIGURE 15 HARDENED SHOE SPLIT SPOON SAMPLER BALL ~ram.'• H E M P H I LL .FIGURE 1.6 INTERCEPTOR DRAINAGE wZem,,evwf SPIRO RESIDENCE page 15 of 67 pages The split spoon sampler, shown in Figure 15, is designed with a precisely beveled 2 inch diameter driving shoe that screws on the end of a split pipe. The split pipe can be opened to recover a soil sample that is driven into the pipe during the Standard Penetration Test. The geotechnical engineer can use the Standard Penetration Test data in conjunction with the visual classification of the soil sample recovered from the split spoon sampler to estimate the relative density of cohesionless soils (granular), and the consistency of cohesive soils (clayey). E. RECOVERED SAMPLES a. Disturbed Samples Samples of each Standard Penetration Test, located at depths as shown on the boring logs, were recovered from the -split spoon sampler for visual classification by the geotechnical engineer. b. Undisturbed Samples 1. Undisturbed samples were not recovered for laboratory testing. Because of. the wet sandy nature of the upper sandy soils, * undisturbed .samples: would have been difficult, if not impossible, to recover" and. prepare for undisturbed, testing. Those soils will not support the pile foundations, and therefore some of the physical parameters of those soils are not important. Stability studies within those soils will presume those soils in a worst condition than presently exists. - The physical properties of the hard clay can be related to the Standard Penetration Test, and to experience with those. soils. The tests necessary to determine the soil modulus of the hard clays for pile design cannot be conducted by any feasible means, therefore those design parameters will be conservative. Some field observations and testing will be conducted to verify the accuracy of the. pile designs. GROUNDWATER OBSERVATIONS Groundwater seeps from the sand/clay intersection higher on the slope, but there is no evidence of any affect on this site. Some groundwater is intercepted by the drainage system shown in red in Figure .16. The volume. of flow from the system is small. The source of the seepage was not determined, but appears to be from the adjacent property to the north. Soils above the clay in the test borings are wet, indicating that groundwater lays and/or seeps on top of the clay. FIGURE 17 CAPILLARITY HEIGHT of CAPILLARY RISE FOR VARIOUS SOIL GRAIN SIZES U. S. STANDARD SIEVE SIZE 100 0! = 90 V C N70 } 60 Q 50 J Q. 40 Q U io r_ 0 �. 20 0 10 W = 0 100 N 90. i t� 80 C 'v 70 w 60 X So g 40 J a Q 30 Q 0 20 10 0 W 0 = 1000 100 10 1.0 0.1 0.01 0.001 GRAIN SIZE IN MILLIMETERS COBBLES GRAVEL SAND SILT OR CLAY COARSE FINE - COARSE I MEOIUM FINE NOTES: A. HEIGHT OF CAPILLARY RISE SHOWN IS TO TOP OF SATURATION; CAPILLARY WATER CONTINUES TO RISE AT LESS THAN SATURATION. B. 111)10 SIZE" IS GRAIN SIZE OF SOIL WHERE 10% OF SOIL IS FINER. SPIRO RESIDENCE page 16 of 67 pages Groundwater seeps from the slope on the property west of Meadowdale Road at the first bench above the railroad tracks. Further studies will be conducted during the grading operations, and during the placement of an interceptor trench behind the west soldier pile wall at the base of the steep slope along the east side of the property. There was no evidence of groundwater or seepage erosion at the site or the general vicinity at the time of the investigation. Groundwater is water below the ground surface that can seep in the direction of gravity flow. For example, if a hole is excavated and water seeps into the excavation, that seeping water is groundwater. Although the soils above the seepage zone are wet or damp, that water is held like a sponge by the soil by capillarity and therefore does not seep. Because of the fine grained nature of clay, silt, and fine sand, the pores hold water much as a sponge does. Water will not run out of those soils until the weight of the water is equal to the force of capillary tension. That height of water is similar to the height that a towel can suck up water from a tub. The finer the weave of the towel, the higher the water rises. Similarly, the finer the soil grains, the higher the water rises in the soil above the normal groundwater level, as shown in Figure 17. At this site surface water that infiltrates the upper granular soils will stop at the undisturbed hard Whidbey Clay and then will build up as groundwater to a depth depending on the height of entrapment, and the rate of seepage from the site. Capillary water will then rise above the top of the groundwater to the height that the finest soils are capable of holding the water, as shown in Figure 17. Soils above the groundwater level that have capillary water are generally stronger than soils below thegroundwater level because the capillary water bonds the soil grains together like a weak 'glue'. When the soils are saturated, as below the groundwater level, then the capillary bond is broken and the soil loses that source of strength.. The capillary bond is a part of the strength of a soil called cohesion. As the groundwater rises more soils can lose the cohesive strength and the stability of the site will be reduced. The stability investigation will be discussed in the next paragraph, and stability studies will be presented later in the report. cn w co TM Cie 0 LL -77 a� s a. - to .... N..:..:. 2 O a' to 7 _ Y� W - II w cc - ui . I I Q U _1 a,. N : .. ._ o a 0 J ate.: r r r SPIRO RESIDENCE page 17 of 67 pages SITE STABILITY INVESTIGATION Since the area is being studied for stability, HEMPHILL investigated the lower slope west of Meadowdale Road to Puget Sound, shown in Figure 18. The slope was measured with inclinometer and range finder. The slope from Meadowdale Road to the railroad ranges from 15 to 25 degrees at a slope distance of approximately 260'. Most of the slope is covered with blackberries, shrubs, and small trees. The shape of that slope appears to be a continuation of the gully that begins on the::: Spiro property, with some" changes in the slope to construct Meadowdale Road, and to construct' the railroad. SOIL DESCRIPTIONS HOW PHYSICAL PROPERTIES of SOILS were DETERMINED The physical properties of the existing undisturbed natural soils at the site were determined from s visual descriptions combined with manual penetration tests conducted on the undisturbed soils exposed in the test pits, and on samples recovered from the test borings. Undisturbed samples of the soils at the site were not recovered for testing, since the estimated minimum strengths and compressibilities of the approved supporting soils exceeds the required maximum strengths and compressibilities for piles, soldier piles, and for temporary support for- f grade beams, and minimal requirements for deck footings and rockeries. Other properties, such as permeability and organic content, were obvious, and were either insignificant, or could be controlled. The allowable supporting soils that HEMPHILL observed at the site are reasonably similar to other soils that have similar visual descriptions, hand penetration tests, and standard penetration tests. The physical properties of those, similar soils have been determined by HEMPHILL and others from constructiom experience, from elaborate field testing, and from specialized laboratory testing. Also available are publications that list the approximate physical properties of those similar soils related to their visual descriptions. Therefore HEMPHILL estimated the properties of the natural undisturbed soils at the site to be approximately equal to the recorded properties of similar soils. SPIRO RESIDENCE page 18 of 67 pages DESCRIPTION of UNDISTURBED NATURAL SOILS The following descriptions and range of physical properties are general knowledge of the typical soils, but are not necessarily the physical properties determined by HEMPHILL for the soils at this site. The actual design values used by. HEMPHILL will be presented later in this report. WHIDBEY CLAY The Whidbey Clay is composed of various .combinations of clay, silt, and very fine sand that were deposited in calm Waters of the lake that existed in the Puget Sound area as the glacier advanced. Since the lake waters were calm, the fine grained soils were laid fairly level. The glacier eventually sat on the Whidbey Clay and compressed it to great densities and strength. Where the Whidbey Clay is exposed on slopes, it is usually stable, and seldom has deep seated slides. Any instability generally occurs in the soils that rest on the clay, or within the upper weathered clay that results from freezing and thawing, wetting and drying, and root action. The Whidbey Clay sometimes has weak surfaces called slickensides that were created when the loads of the accumulating soils, and/or the glacier, caused the soft clays to shift down in one place and up in another. The movement was usually circular and occurred in a small area. The movement created a slide plane where the soil grains became permanently aligned, even after being greatly compressed by the glacier. The slickensided surfaces cause chunks of Whidbey Clay to fall out of exposed surfaces and in excavations. The slickensided surfaces seldom cause. deep seated slides, and have very little effect on vertical bearing capacity, compressibility, and permeability. The Whidbey Clay sometimes contains vertical relief cracks where it is exposed along some slopes that were carved by the glacier or other erosion after the clay was compressed. The relief cracks were the result of the removal of. great loads that once contained the Whidbey Clay laterally prior to the removal of the. soils that were once adjacent to the slope. The relief cracks can exist for great distances into a hillside, depending on the extent of the lateral pressure of the removed soils. Water seeps into the cracks and softens.the soils, creating weak joints. The weak joints and hydrostatic pressures in the joints can cause deep seated slides in the Whidbey Clay, and can also cause the Whidbey Clay to fall off steep slopes in chunks. That type of failure generally occurs where the slope is adjacent to wave. action or running water that constantly washes, away any accumulation of slide or erosion debris at the toe of the slope. If the debris can accumulate, the build up will eventually cover the slope and will provide lateral support, and also protection against weathering. SPIRO RESIDENCE page 19 of 67 pages The undisturbed Whidbey Clay generally has bearing strengths of 6000 to 8000 psf, has very low compressibility, low permeability, a friction factor of approximately 0.2 to 0.3 (depending on the other material involved in sliding), and side friction on piles of 1000 to 2000 psf (depending on the pile material, and the initial pressure when the pile is placed). The undisturbed glacially compacted Whidbey Clay can be confused with Whidbey Clay that has been disturbed by weathering, sliding, and rebounding and cracking from relief. The undisturbed Whidbey Clay can also be confused with silts and clays that were deposited in the glacial lake as the glacier receded, and therefore were never over ridden by the glacier. The Whidbey Clay can also be confused with stream, river, and lake deposits that occurred since glacial times. Because of the great difference in physical properties between the undisturbed Whidbey Clay, and either disturbed Whidbey Clay or other clays, only a geotechnical engineer should evaluate the physical properties of any clay or silt type soil. ESPERANCE SAND The Esperance Sand in its undisturbed condition exists farther up the slope and has no -effect on this site. Esperance sand has been eroded from the upper slope by stormwater runoff and groundwater seepage, and has been deposited at the site: The source" of some or all of the upper loose soils at the site could be eroded Esperance Sand, but those eroded soils would not have the same -properties as the undisturbed glacially compacted Esperance Sand. Following is a description of the undisturbed Esperance Sand, how it was formed, and its its properties and why it poses no effect on this site, and how it got to the site. The Esperance Sand is composed of various combinations of sand, silt, and gravel that were deposited in the glacial lake by the Vashon Glacier. Since the grains of the Esperance Sand were heavier than the Lawton Clay particles, they settled faster into the glacial lake, and were therefore -deposited closer to the advancing glacier. The more slowly settling clay particles were carried farther away from the glacier. Therefore, as the glacier advanced, the Esperance Sand was deposited on top of the Lawton Clay. The advancing glacier eventually compressed the Esperance Sand, and also the underlying Lawton Clay, to a very dense condition, therefore the Esperance Sand in its undisturbed condition is very strong, and seldom has deep seated slides unless it is loosened by weathering or undercut by erosion. Those soils would slide farther up the slope in thin layers and generally remain close to their source, therefore the undisturbed Esperance Sand is not likely to pose a threat to the Spiro house. Weathering, which is caused by wetting and drying, freezing and thawing, and root action, loosens the surface of the very dense Esperance Sand, and causes the surface to lose strength. HEM PHILL page 20 of 67 pages The loosened sand will slough to the base of the slope, which is farther up the slope where a bench has been created, and the slope is gentle, from past sloughing. The weathering and sloughing process can continue, with the loosened soils building up the slope at their natural angle of repose, until the entire slope is covered.with sand at the natural angle.of repose of the weathered soils. The underlying undisturbed sands are then protected from weathering, and the slope is then stable. The undisturbed Esperance Sand is easily eroded by runoff and streams, and also by. seeping groundwater which generally occurs where the intersection of the Esperance Sand and .the Lawton Clay is exposed on a slope. Stream action at the base of the slope, and/or groundwater seepage .on top of the Lawton Clay, can erode the base of the Esperance Sand, and then undercut the upper slope. That undercutting process causes the eroded sand to slide to the base of the slope. If the sloughed . sands at the base of the slope are not carried away by stream or wave erosion, then the eroded sands will build up the slope, and will eventually cover the seepage zone, and will prevent the seeping water from eroding the overlying sand. Wave action has apparently prevented the build-up of the sloughed sand at this site, or the weight of the sloughed soils caused the soils in the gully to slide out toward Puget Sound. Disturbed Esperance Sand that has been loosened generally has a natural angle of repose that ranges from 35 to 40 degrees, depending on the grain size and the cohesion of the.finer soils. RECESSIONAL GLACIAL OUTWASH & BEACH DEPOSITS Recessional glacial outwash & beach deposits are generally composed of any combination of silt and fine sand to coarse gravel that either washed out of the glacier as it receded, or eroded from the slopes. . Recessional glacial outwash and beach deposits were loosely deposited by running water, or within an entrapped glacial lake, and were never over -ridden by the glacier. Glacial outwash and beach deposits generally have a natural angle of repose that ranges from 25 to 45 degrees, depending on grain size, groundwater conditions, and some binding by silt. Glacial outwash and beach deposits are generally fairly pervious, therefore.. stormwater infiltrates easily. On slopes where stormwater does not infiltrate, or where concentrated uncontrolled runoff occurs and the surface is not protected by vegetation, erosion can be very. severe. z O LU Cl) V 0 0 O w C) w Q W 0) TT w 0 LL w ............... ..................... . _ ............. LLI m :: .. -. . .. Cl ..:::::::: . . . cc:_ .. 7 .........7 ao> -7777. -- - -- ,. - q. m -_- - - p - s w yj a::i: ........ o... . .... N - - - --- 77 ....... .......................... . y i.. N cr 0 m 2v�d, a -- -- .... 3 _ _ __ _ ..... ...... ....... .. i -- - a - .cn.::..:: . w ........: . ; N ..... . a N - N a i IL)cc w ...::... ..::'yd O.::... w - — p - (g w -- _ - - w -.--: :::::...... — .::.-:... . W 0 N it w cr Q D a U) r J a U 0.o Q J W LL � Q ZLLI 3a =..-W Q Z �o CO W g0 UW 0 Q Q J �Z w� aO aCI)s �W Ncc W W F_ Q Z W Z 0 0 Q cr C7 a r N IF is SPIRO RESIDENCE page 21 of 67 pages Groundwater is often encountered at the base of glacial outwash and beach deposits where the underlying soil is less pervious, such as at this site where the underlying soils are the Whidbey Clay. If those conditions occur on a slope, high saturation at the base of the granular soils can cause unstable conditions. The bearing capacity of granular glacial outwash and beach deposits have a wide range, depending on the composition of the soils, the depth, the size, and the shape of the footing, and groundwater conditions. Generally loosely deposited granular soils with some silt, that has settled under its own weight, that has been water settled, and that has had time for desiccation, can support loads in excess of 2000 psf with minimal settlement. Frictional resistance to sliding between the granular soils and structural components ranges from approximately .3 to .6 times the vertical load. Lateral loads on retaining walls and rockeries can range from very high for soupy silty sands during unusually wet conditions, to nearly O'for more granular very pervious soil capable of supporting itself. CONCLUSIONS The site has been unstable in the past, but according to the neighbors there has been no noticeable movement since 1947. The property west of Meadowdale Road has many undulations that could indicate some movement, but it could also be the result of grading and filling. The lower bench just above the railroad has a seepage zone, but the slope at that location is gentle, and there is no evidence of movement. The seepage could be occurring on the top of the hard Whidbey Clay. Figure 19 shows that thesteep rear slope of the Spiro property is the hard Whidbey. Clay overlain with weathered clay, and possibly some slough debrisfrom higher on the. slope. Because of the great strength of the undisturbed Whidbey Clay, a deep slide in the*steep rear slope is unlikely. Any instability of that slope will be the result of minor surface sloughing. There is no evidence of slough soils on the bench at the base of the steep slope. The test pits revealed that the bench at the rear. (east) of the property is composed of various combinations of coarse sift; sand, and gravel. Those soils are, partially cemented with a rust colored. matrix, which fits the description of the Double Bluff Drift shown as Qdb on Figure 8 on page 9.. Figure 8 shows the Double Bluff. Drift in the vicinity of the site. It appears that the Double Bluff Drift might be a recessional outwash.that was deposited against the steep slope by the glacier as it receded. The test pits show that the Double Bluff Drift is directly over the hard Whidbey Clay. Figure 19 shows the estimated location of the Double Bluff Drift. HEM PH I LL SPIRO RESIDENCE page 22 of 67 pages The test borings show that the loosely deposited fine granular soils with the small clay chunks are directly over the Whidbey Clay. There is no evidence of the Double Bluff Drift in the test borings, therefore that soil apparently makes up the bench and stops at its natural angle of repose on top of the clay. Therefore that soil. was in place before the 'beach deposits' were deposited. Some of the Double Bluff Drift was probably eroded by wave action and became part of the beach deposits. The test borings show that the top of the clay slopes down to the west, and probably continues to the seepage zone at the base of the slope just above the railroad tracks. Figure 19 on the previous page shows the estimated location of the hard Whidbey Clay. Some groundwater enters the interceptor drains located at the base of the bench, but the water apparently comes from the property to the north, since no water enters the system at the base of the bench. That interceptor pipe might not be deep enough to intercept water that seeps on top of the clay. Groundwater that can seep is located near the top of the hard clay. There is no evidence that the water surfaces before the lower slope on the property west of Meadowdale Road. Figure 19 on the previous page shows the estimated location of groundwater. Nearly all the soils at the site will hold capillary water, which will be discussed later in the report. Soils that have capillary water will be stronger and more stable than soils that are below the seeping groundwater level HEMPHILL FIGURE 20 MAP of SEISMIC ZONES 3 3 q�r 3 3 � 3 Zone 1 — Distant earthquakes with fundamental periods greater than 1.0 seconds may cause minor damage. Corresponds to intensities V and VI on the Modified Mercalli intensity scale. ' Zone 2 — Moderate damage: corresponds to intensity V11 on the Modified Mercalli intensity scale. Zone 3 — Major damage: corresponds to intensity VII I and higher on the Modified Mercalliintensity scale. Seismic zone map of continental United . States (After Algermissen, 1969) Seismic Coefficients Corresponding to Each Zone. INTENSITY OF MODIFIED AVERAGE SEISMIC ZONE MERCALLI SCALE COEFFICIENT REMARK 0 _ 0 No damage I V and VI 0.03 to 0.07 Minor. damage 2 VII 0.13 Moderate damage 3 VII and higher 0.27 Major damage 3 SPIRO RESIDENCE page 23 of 67 pages ENGINEERING STUDIES and RECOMMENDATIONS RATIONALE for RECOMMENDATIONS The geotechnical recommendations presented in this report for the proposed PROJECT are based partially on presumptions by HEMPHILL, and on the requirement that HEMPHILL will verify the presumed conditions, and will make final decisions for depth of piles, slope stability, any retaining systems, structural fill, slabs, paving, and for drainage, at the time that the excavations reveal the true nature of all the subsurface soils. SEISMIC STUDY HEMPHILL conductedan investigation to determine the potential for seismic vibrations to cause slope failures, resulting from increased lateral forces and reduced soil strengths, and from settlement, resulting from densifying and liquefaction of soils. INCREASED LATERAL FORCES Lateral forces are created by the lateral vibrations created by an earthquake. Those lateral vibrations accelerate to a maximum velocity, and then decelerate to zero, then reverse and_ accelerate to the maximum velocity again. The acceleration and deceleration of the mass of soil in the slope is caused by the lateral forces caused by the earthquake. Since a force causes a mass to accelerate, that seismic force causes the soils to move laterally, which can cause a slope failure if that additional force, along with the other driving forces that already exist on the slope, is. greater than the strength parameters (friction and cohesion) of the soil that would resist slope failure. Figure 20 shows a map of seismic zones that lists the Puget Sound area as Zone.3, which can have earthquakes with intensities of VII or greater. Figure 21 on the next page gives descriptions of the intensities. Figure 20 also shows the average seismic coefficient for a Zone 3 classification to be 0.27. According to some publications; that number is low for poor soil 'conditions and high for good soil conditions. Some experts state that the seismic coefficients have no basis from experience, and therefore are arbitrary. HEMPHILL used a seismic coefficientof of 0.15 for . slope stability studies presented in the next section of this report,, which is recommended by some local building departments. The source and accuracy of the recommendations is not known, but the values have. been accepted as standards and are considered acceptable for engineering purposes. A higher. value might be appropriate where a slidemight be life threatening, which is not the case at this site. HEMPHILL 71 FIGURE 21 DESCRIPTIONS of SEISMIC INTENSITIES ABRIDGED MODIFIED-MERCALLI INTENSITY SCALE* I. Detected only by sensitive instruments. II. Felt by a few persons at rest, especially on upper floors; 7 delicate suspended objects may swing. III. Felt noticeably indoors, but not always recognized as a quake; standing autos rock slightly, vibration like passing truck. IV. Felt indoors by many, outdoors by a few; at night some awaken; dishes, windows, doors disturbed; motor cars rock noticeably. V. Felt by most people; some breakage of dishes, windows, and plaster; disturbance of tall objects. VI. Felt by all; many are frightened and run outdoors; falling plaster and chimneys; damage small. VII. Everybody runs outdoors; damage to buildings varies, depending on quality of construction noticed by drivers of autos. VIII. Panel walls thrown out of frames; fall of walls, monuments, chimneys sand and mud ejected; drivers of autos disturbed. IX. Buildings shifted off foundations, cracked, thrown out of plumb; ground cracked; underground pipes broken. X. Most masonry and frame structures destroyed ground cracked; rails bent; landslides. XI. New structures remain standing; bridges destroyed;. fis- sures in ground; pipes broken; landslides; rails bent.. XII. Damage total; waves seen on ground surface; dines of sight and level distorted; objects thrown up into air. *This scale is a subjective measure of the effect of the ground shaking and -is not an engineering measure of the ground acceleration. SPIRO RESIDENCE page 24 of 67 pages The seismic coefficient is a mathematical convenience, which is the lateral acceleration of the soil mass compared to the vertical acceleration of gravity. The true acceleration used to calculate the lateral soil forces is 0. IS x 32 ft/sec/sec = 4.8 ft\sec\sec. The weight of the soil can be converted to mass (slugs) by dividing by 32 (acceleration of gravity), and then the soil mass can be multiplied by 4.8 to determine the lateral force, but it is mathematically convenient to just multiply the soil weight. by 0.15. SETTLEMENT from SEISMIC CONDITIONS Granular soils that are deposited in nature are generally loosely placed either by water or wind. Granular soils are sometimes loosely deposited by man in uncontrolled fills. Such loosely deposited soils have fairly large void spaces, sometimes called pore spaces. As more soils are deposited the loose soils will be pushed closer together until the soil grains contact each other, but not necessarily in the most compact condition. As the weight of overlying soils is increased, the contact force between soil grains increases, and the grains have more difficulty. sliding past each other to become more dense. That resistance of the soil grains to sliding into a more dense condition is the frictional resistance of the soils. That frictional resistance is one of the conditions that gives soils their strength to resist shear failures as heavy building loads are applied. The other condition that gives soils strength is cohesion, which is a sticky condition generally associated with clay and sift, and is nearly non-existent with coarse granular soils. Fine and medium granular soils are held together by dampness between the grains that bonds the grains. like a'weak .glue'. That bond between the grains can be lost by drying the soils, or by saturating them. That condition is well known by children playing in a sand box, where dry sand cannot be formed or molded, damp sand can be molded, and a molded sand form can be destroyed by pouring water over it. That water 'glue'- is called capillary tension, which can only exist in granular soils when they are damp, and cannot exist in dry or saturated granular soils. That capillary tension is also what holds together clay soils and makes them sticky. The smaller the soil grains, the greater effect that a water bond has between the grains. Unless an extremely heavy load is applied to the deeper granular soils, the intergranular friction, and sometimes the capillary tension if the soils are damp, prevents the soil grains from sliding into a more dense. condition, and they remain relatively loose. If the soils are suddenly jarred by an earthquake, the friction forces will be temporarily reduced, and the soil grains can be forced into a more compact condition when the weight of the upper.soils is reapplied. As the seismic vibrations cause reduction and reapplication of the friction forces, the._ volume of the existing voids will, be reduced, and the soils will settle an amount equal to. that. reduction in .voids. That sometimes causes a large area to settle an equal amount, and differential settlement can be minimal. Differential settlement of a structure can cause structural damage, and differential settlement outside the structure can cause external drainage and sewage lines to reverse flow, or'can stress utility lines to the rupture point. FIGURE 22 �� 10 20 30 DEPTH (ft) 40 50 7n LIQUEFACTION ASSUMED WATER TABLE I. I MAXIMUM GROUND ACCELERATION OA g I 0.15g 0.2g 0.25g LOOSE' MEDIUM DENSE VERY DENSE 0 1'.0 20 30 40 50 60 STANDARD PENETRATION RESISTANCE (blows/ft) NOTES: THE VALUES. SHOWN IN THE CHART ARE CONDITIONS FOR WHICH LIQUEFACTION IS..UNLIKELY TO OCCUR (AFTER SEED and IDRISS) THE REQUIRED GROUND ACCELERATION TO CAUSE LIQUEFACTION INCREASES WITH DENSITY, AND ALSO WITH DEPTH FOR THE SAME SOIL DENSITY, BECAUSE THE WEIGHT OF THE .UPPER. SOIL INCREASES THE STRESS BETWEEN THE SOIL GRAINS WHICH.THEN INCREASES THE RESISTANCE TO MOVEMENT OF THE SOIL GRAINS INTO A MORE DENSE. CONDITION. SPIRO RESIDENCE LIQUEFACTION page 25 of 67 pages Another condition that occurs within loose granular soils during a seismic condition is called liquefaction. Liquefaction occurs'two ways; by rising groundwater creating a 'quick' condition, and by trapped porewater reducing the strength of the soils. When granular soils that are below the groundwater level settle quickly during a seismic vibration, the, groundwater that filled the void spaces of the loose granular soils is displaced and forced to rise. If the groundwater rises fast enough in more pervious soils, and can rise to the ground surface, then a 'quick' condition occurs. A quick condition is similar to the cause of quicksand, where the rising water moving past the soil grains reduces the frictional contact between the grains, and therefore causes a reduction of bearing capacity. The rising groundwater also saturates the previouslydamp granular soils and breaks the capillary tension bond. Therefore the soils have. reduced load bearing capacity by losing frictional contact between the grains, and by losing the capillary tension bond. The 'quick' condition is also caused. by increased pore water pressures that prevent the soils from maintaining frictional contact. When the sand. grains have reduced friction caused by a vibration,. and attempt to move into a smaller space, they are resisted by the porewater that hasn't been able to seep out of the pores as fast as the soils are settling. The soils are then supported by the porewater which acts like small hydraulic systems. Of course, water has no strength to resist shearing, therefore the porewater and reduced soil friction combination will fail under the imposed! loads of the upper soils and the structure. Another type of failure caused by liquefaction occurs on slopes. A slope failure can occur within much deeper soils than a footing failure because the soils on the outer surface of the slope. can fail, and then a chain reaction will occur as the friction forces deeper within the, slope are reduced as each layer of the overlying soils slide away. Liquefaction can cause a failure on a slope even when the sand soils are covered by stronger or more cohesive soils that are not affected by the seismic vibrations Granular soils that have a greater frictional resistance to sliding into a more compact condition, either from being -more dense, or that have a greater overlying load that both increases friction and also resists the, upward vibration movement of the soils to release the frictional contact, will have a greater resistance to settling and/or liquefying from seismic vibrations. Figure 22 is a graph that shows the probability of liquefaction based on the effect of seismic accelerations on saturated sands at various depths and with various densities..Assuming a density of 'medium dense',` liquefaction could occur at the design acceleration of 0.15 x g in granular saturated soils above 35 feet from the ground surface. Since the potential line of failure, the -top of the hard clay, and the groundwater level are all above critical. depth of 36 feet, then liquefaction could occur at this site. cn W_ a Cr/� ♦ J vM W cn L 0 Z 0 V W U) M N W m D 0 LL 0 M O O O' O O 01 P- to M 0 N II W cc Q D a N r ui J Q U N L SPIRO RESIDENCE SITE STABILITY page 26 of 67 pages Figure 23 shows a section of the slope which includes the proposed house location and the property west of Meadowdale Road to the railroad. HEMPHILL assumes that the railroad is stable and supports the toe of the slope. There are ten points on the slope (A thru J) that define the shape of the slope to conduct slope stability calculations. An example of the calculations is shown in Figure 24 on the next page. The stability calculations are conducted at each point on the slope by dividing each slope into a series of slices, and calculating the safety factor against sliding for each slice. The stability of each series of slices is determined at various angles of slide plane, starting at 10 degrees and continuing at 2 degree intervals from each point on the slope where the slope changes direction. A seismic factor is included in the calculations based on the assumption that the lateral shaking will add lateral forces on each slice equivalent to 15% of its vertical weight, as previously explained. The -15% (0.15) is multiplied by the weight of the slice plus any external loads that are on the slice. There are no external loads included in this investigation. The house will not add loads to any slices because the piles will carry house loads to the soils below the critical potentially unstable soils. The estimated soil and slope parameters used to conduct the stability study are shown in Figure 25 on the next page. The shape of the slope was determined by the topographic plan shown in Figure 7, and by measurements conducted by HEMPHILL with inclinometer and range finder. The soil parameters are the worst estimated conditions, and are considered by HEMPHILL to be conservative. HEMPHILL 3dOlS 10 301 JO NOUVIS OH3Z 10 3NIl N z 0 F- g D U Q U L ° z III (n 0 U w U J cn 0 _ F- a W U J W N x C) U- 4O w a O J N W `O a w 0 0 J � U L O O W z O O� Q W J Q W 0 m W N O � w z J' 301 WOHA 1HJI3H JO 3011S 10 d0110 NOIIVA313 i w t= i= Z z (n 2 N c°) v cc x LL w cn LLI_ / a II W (n > _ F- W J U) Q Zo N FN F 0 cnp N F= O 00. Z 0 cr - Z w w D W Ww ZU v,.. z w� 0 J:N wu a .� Z x Z + 0 U f= z J J N Q O OJ 0(.) �.N LL.N J v cc x 3 z www -i u°f,..~ �H OwWNv 0U)-jZi O :z J_ dZ Z(n00Q u, (AW�`yW d��F it WU} y0ZO� +O H U x O N° J.���nO0Ill(tcnwQa; NVO �cU) �QNaLCC LIIL) IX1.-00CC H - t-0Czcc050WOz LLa4..a °�0�UI-QOVO�Ow� `m _jn.ul =ga2awF-Uww 0g=U(n�cc2U) a:LL z O O R w w o o m o o c O Q o 0 0 0 LL (n z U w 0.0 LL ;w w V II II II tl II II II II II U it II II m ? O) dl V �. O. LL z LL (n LL LL.LL LL N Q SPIRO RESIDENCE page 27 of 67 pages FIGURE 25 DATA for SLOPE STABILITY CALCULATIONS --------------------------------------------------- --------------------------------------------------- D A T A f o r S L O P E S T A B I L I T Y ----------------------------------------------------- ------------------------------------------------- P R O J E C T D A T A --------------------------------------------------- CALCULATION TRIAL NO. : 5 DATE of CALCULATIONS : .11/20/90 PROJECT NUMBER : 1636 NAME of CLIENT : SPIRO FAMILY PROJECT NAME : SPIRO FAMILY HOUSE LOCATION of PROJECT : RAILROAD to REAR of HOUSE --------------------------------------------------- S L 0 P E D A.T A --------------------------------------------------- LOCATION of SLOPE CHANGES SLOPE MEASUREMENTS ----------------- - ------- ----------------------- STATION ELEVATION RATIO ANGLE POINT (ft) (ft) SLOPE (V : H) (deg) --------------------- --=----------- ----- A 0 31 AB 0.5 : 1 24 e 41 50 BC 0.1 : 1 3 C 56 51 CD 0.2 : 1 14 D 124 68 DE 0.4 : 1 19 E 246 112 EF 0.0 : 1 0 F 284 ..112 FG 1.0 1 44 G 290 118 GH 0.1 1 4 H 375 124 HI 0.7 1 33 I 405 144 IJ 0.0 1 2 J 430 145 -------------------- S O I L D A T A POTENTIAL SLIDING SOILS are SILTY FINE SAND UNDERLYING COMPETENT SOILS are HARD CLAYEY SILT UNIT WEIGHT of SOILS = 130 pcf INTERNAL FRICTION of SOILS = 10 deg COHESIVE STRENGTH of SOILS. = 300,psf MINIMUM ANGLE of.SLIDE PLANE = 10 deg MAXIMUM ANGLE of SLIDE PLANE = 20 deg INTERVAL of SLIDE PLANE ANGLE = 2 deg INTERVAL of HORIZONTAL CALCS = 10 ft FACTOR for SEISMIC VIBRATIONS = 0.15 --------------------------------------------------- --------------------------------------------------- HEM P H I L L . 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VI P M A O V• O N O V\ O M A 19,t aO .F . V. V. �} �t .t a. •a�7 NN •O ^ . ap'NNNN a0 .t A d O..ppMar� It IC aavv is V.pMa • aO.O M—O AM CO M O Lt d J.�-•It co mCV;'N—----�OOO PPPa0 aD A1�a�•O .O .O .O Mv\M MvJdMM — ~ •O •O •O .O .O •O .O O •O •O •O •O .O `O •O d .O •O •O •O .O .O •O •O .O .O .O •O O •O •O .O .O .p .O •O `O •O •O •O •O •O •• J J v v d vM MM M It MM MMN N NNNNNN NN �---NJ ^N—O—P tO A.OMN— ' W <O W d v Z SPIRO RESIDENCE page 28 of 67 pages The worst safety factors occurred on a slope of 14 degrees located at point A, therefore only that set -of calculations are shown in Figure 26. Figure 26 shows the calculations to determine the slope stability, and shows that the safety factors for the worst 10 foot slices under normal conditions (static) were 1.2 at point A with a 14 degree failure plane angle, and the worst safety factors for seismic conditions were 0.3. Although individual slices had low safety factors, the entire slope had a much higher average safety factor, because slices farther down the slope would require greater forces to begin sliding, and therefore will hold back the slices with lower safety factors. For seismic stability the overall slope does not show failure because of the stability of the lower slope, but the weaker slices might rotate out from the slope somewhere near the middle. The weakest portion of the slope is near the west edge of Meadowdale Road, and an actual slide might occur west of the road with the head scarp near the west edge of the road. The calculated line of worst slope passes through the known top of hard clay located in the borings. The true toe of a slope failure might curve into point C where the seepage zone exists. Although both the static and seismic safety factors exceed 1.0 at the site of the proposed house, they are not sufficient to assume that the site will always be stable. Slopes FG and HI show some minor instability because of the steepness of the slopes: Slope FG is not high enough nor in a potentially hazardous location, and slope HI will be supported and the stability will be improved. Slope HI is also composed of the more stable Double Bluff Drift. The stability of the site of the proposed house will be improved because the rear bench will be lowered, removing some of the driving loads, the rear steep slope will be supported by a soldier pile wall,. and the piles for the house will help to hold the adjacent soils. An interceptor drain placed behind the soldier pile wall, and drainage for the house, will also improve the site stability. SITE PREPARATION CLEARING and STRIPPING In those areas where the structure, paving, or special landscaping will be placed, the ground surface should be cleared of any trees and shrubs, high grass and weeds, debris, and trash. The ground surface within the proposed structure, and under any footings or paving, should be stripped of any sod, organic soils, and roots. NO ORGANIC MATERIALS CAPABLE OF DECOMPOSING SHOULD BE LEFT WITHIN THE PROPOSED STRUCTURE. Decomposing materials are the source of unacceptable odors, and can create methane gas, which can be explosive, and can also be harmful when inhaled. . C) z Cl) U — O a � t- o Z w. a O CL a w w v a LL i m 0 :D w D Z a 2 w cc U O O CL ti N w m D a CL p p 0w--� W w W cc: > = p O cn (n Q 2 0 w a U Of w J0W w cr: 0m w W Q~ Q > U W U — p cw C'3 w Opp O Q w JO w w W Q a:w T-' 2 O �m� � O U Q� J O U) wZ_ p LL Q = cc J w O U)O U UQ _ZW0(.) U OZ O wQ �� �Qac L. cr Q W _J OU F- OAF----Ug O pcn 0 �U �WZ¢O n crF-D�LLo .t U) O0Z cn 02. Q Z F— O> E. F- O Q U wcl: Q c�(r � QgQ� w 0 o O w. O. Q O ac �UWZ p m JQ Utlj C7Cr�0(� Z C) W-j OZC'3� U w ZCO cn N QHQ O cn < O U) H- U)O w CC zb: �� CEO.- p>Q'O Q Cn U cr J) w p2 (1)CC WO:.5p. .cr CL w Z a: p> �Ld < �m w a: cr O mp >w.>�QQw OC .mwU) J Z g W J i- a w� 0= =°C= g. W W O t-- ¢ F- w 0 �. HCL aZ wcr z W W LLJ a �-w UY CO 0- w Q m U SPIRO RESIDENCE page 29 of 67 pages PROOF ROLLING PURPOSE OF PROOF -ROLLING Proof -rolling will density the upper layer of soil, will compact any soil loosened by excavating operations, and will locate soft spots that should be excavated and replaced with structural fill. If the condition of the underlying soils is questionable, HEMPHILL might require that the soils be proof -rolled. DESCRIPTION OF PROOF -ROLLING Proof -rolling of a soil is accomplished by several passes of a heavy compactor. At those locations where the condition of the underlying soils is questionable, HEMPHILL might require that the soils be excavated and replaced with structural fill. PLACEMENT of WORKING SURFACE on SOFT SOILS Some of the existing soils at this site have a high sift and clay content. During wet periods, or before the soils dry sufficiently, construction activities on those soils will be difficult, if not impossible. The construction activities will cause any disturbed soils to become less dense, and to lose strength. If construction is scheduled during wet periods or while the soils are wet, and the soils become soft and difficult to support construction activities, ,then a working surface composed of coarse crushed rock can be forced into the soft soils that will then support the construction equipment, will protect the underlying soils from disturbance, and might be a satisfactory base for the structure, and pavement. The site should be stripped of the upper vegetation and organic soils. Poorly graded crushed rock should be placed over the existing soft site soils and then forced into the softer soils by a heavy vibrating compactor, as shown in Figure 27. This procedure requires close supervision to ensure that the crushed rock is forced to the more competent layers below, and rises above the soft and wet soils, and that the soft soils do not support the rock, but fill the void spaces between the crushed rock. GENERAL SITE EXCAVATING REMOVAL of UNACCEPTABLE SOILS Any existing fill and/or any loose or soft soils that are considered unacceptable by .HEMPHILL should be removed from the ground surface with as little disturbance as possible to the acceptable soils that remain in.place. Those unacceptable soils should either be removed from the site, or used for landscaping, provided that the placement of the soils does not create any instability. v 0 Cl) w x w co N w m D LJL SPIRO RESIDENCE page 30 of 67 pages EXCAVATING to SITE GRADE The proposed excavating will be conducted to lower the bench along the east side of the site. Lowering the bench will allow easier access to the garage. A soldier pile wall will be installed to support the upper slope prior to the excavating. Figure 28 shows the soils to be excavated, and the soldier pile wall. MAXIMUM EXCAVATED SLOPES HEMPHILL recommends that the final grade of any slopes that are excavated and not protected should not exceed a slope of 1 vertical to 2 horizontal for easy maintenance, better erosion control, and stability. If steeper slopes are desired, then the maximum steepness of the slope will depend on the type of soils, their physical properties, groundwater conditions, the proposed height of the slope, the proximity of the slope to adjacent structures, and landscaping and maintenance requirements. The existing Double Bluff Drift can stand nearly vertical for many feet, but will gradually lose its surface due to weathering from wetting and drying, freezing and thawing, minor groundwater seepage, surface erosion from stormwater runoff, and root action. The maximum slope that the Double Bluff Drift could stand permanently is approximately 1 vertical to 1.5 horizontal. EXCAVATING for STRUCTURE Portions of the bench will be excavated from under the garage and house, as shown in Figure 28, but any other excavations will be for placement of crawl space, piles, and grade beams. Except for the east half of the garage, the rest of the structure will'be over crawl space. The interior portion of the structure, and the working space for the construction offorms for grade beams, will be excavated approximately 2' feet below the final ground surface. HEMPHILL recommends that. the excavations for the garage and the house be sloped to the northwest a total of 6 inches or. 1 /1U to allow any interceptor drains, and any water, in the crawl space or under the. garage, to flow to the northwest corner, and to prevent the accumulation of groundwater in the crawl space or under the garage slab. ALLOWABLE SLOPES for SIDES of EXCAVATIONS Deep excavations are not anticipated at this site.. If unexpected, excavations should be required, then any excavations less than 4 feet deep can have the sides sloped as steeply as they can stand. Where workers will be active adjacent to the sides of excavations that are deeper than 4 feet, the sides of the excavations should be 'sloped no, steeper than 1 horizontal to, 2 vertical for the protection of the workers. Some soils might require slopes.less steep. HEMPHI LL SPIRO RESIDENCE page 31 of 67 pages Safe slopes within the excavations should be made the responsibility of the contractor, and should be accomplished in compliance with current local, state, and federal codes and practices. Such codes would include the Occupational Safety and Health Act of 1970 (OSHA) and the 'Safety Standards for Construction Work' of the State of Washington, Department of Labor and Industries, Division of Safety. GENERAL SITE FILLING The only anticipated fill will be placed to construct the driveway, and possibly for some landscaping. The driveway must be constructed of structural fill to resist settling and to be capable of supporting vehicles and the back porch. The fill must also resist frost. If the depth to subgrade and/or allowable bearing soils is greater than anticipated, the contractor can choose to over -excavate to soils approved by HEMPHILL, and then to backfill to the required grades with structural fill approved by HEMPHILL. With the approval of HEMPHILL, the contractor can choose the structural fill from among those soils available from commercial suppliers, from offsite borrow pits, or from any existing site soils that are determined by HEMPHILL to be satisfactory for structural fill. The excavated Double Bluff Drift might be an excellent structural fill. DESCRIPTION of RECOMMENDED STRUCTURAL FILL Structural fill is defined as any soil that can be properly compacted to achieve any or all of the physical properties that are. necessary to support foundations, to diminish building and paving loads to softer soils below, to undergo acceptable settlement, to resist attracting capillary water to the underside of the floors, footings, and paving, and to be workable when wet. Many combinations of grain sizes would be satisfactory as a structural fill soil, depending on the water content of the soil, and on weather conditions. During wet weather or any wet conditions, soils with greater than 5% passing the no. 50 sieve will be difficult, if not impossible, to compact. With the approval of HEMPHILL, the contractor can choose the structural fill from among those soils available from commercial suppliers, from offsite borrow pits, or from any existing site soils that are determined by HEMPHILL to be satisfactory for structural fill. The properties of most acceptable soils that are properly prepared as structural fill are well documented, and can be easily estimated by a geotechnical engineer. HEM PH I LL SPIRO RESIDENCE page 32 of 67 pages PREPARATION of EXISTING GROUND SURFACE for FILL Prior to placement of structural fill on the existing ground surface, high grass and weeds, tree roots, loose piles of soils, debris, any unacceptable fill, any organic soils, and any loose or soft soils considered unacceptable by HEMPHILL should be removed from the ground surface with as Tittle disturbance as possible to the undisturbed soils that remain in place. When structural fill will be placed on an existing slope of finer grained soils, the slope should be excavated so that the structural fill is placed on a nearly level surface to prevent the fill from sliding down the slope. The slope can be excavated to a series of steps approved by HEMPHILL PLACEMENT of STRUCTURAL FILL on SOFT SOILS During wet weather, if a working surface has been placed, the structural fill can be placed directly on the working surface in 8 inch layers, and compacted to the required density. If a working surface has not been placed, and the existing site soils are soft and cannot be removed without disturbing some of the underlying soils, then the first layer. of structural fill can be placed with the maximum thickness that will allow the compacting equipment to work without causing rutting. If more than 12 inches of fill is needed to prevent rutting, then lighter compaction equipment should be used. The first layers should be compacted with several passes'of a heavy vibratory compactor. Each additional lift should be 8 inches or less and compacted to the required density. CONTROL of COMPACTION of STRUCTURAL FILL LABORATORY TESTING The proper compaction of a structural fill is generally related to the densities achieved by a Modified Proctor Test. A Modified Proctor Test (ASTM D-1557) is conducted on each different soil type to be used for filling to determine the required minimum density of the structural fill to achieve the desired properties. The Modified Proctor Test also determines the optimum water content that will best achieve that density. A Modified Proctor Test is achieved in a soils laboratory by conducting a series of compaction tests, each with a different water content. Each test is conducted by compacting a specific volume of the soil with precise compaction procedures with a controlled or measured water content.. A curve is plotted comparing the density achieved for each water content of the soils during the test. SPIRO RESIDENCE page 33 of 67 pages The highest point on the curve shows the water content at which the density of the soils is the greatest. The maximum density on the curve is called 100% of the Modified Proctor maximum density, and the water content that achieved that density, is the optimum water content at which the soil compacts most easily. At that density the soils are considered to be capable of supporting their maximum loads with minimum compressing, or settlement. The results of Modified Proctor tests are different with different soils. The geotechnical engineer must be capable of recognizing soils that will have different properties when compacted, or he should conduct periodic classification tests to identify different soils. HEMPHILL should determine when a. Proctor Test is required on a different soil type. PLACEMENT of STRUCTURAL FILL Sometimes the desired properties of a structural fill can be less than those achieved at 100% of the Modified Proctor, and the geotechnical engineer can specify a lower value, such as 90% or 95% of the maximum density achieved in the Modified Proctor test. The properties. of the structural fill can either be determined by testing in the laboratory, or by comparing with known properties of a similar soil that have been determined by past testing by the geotechnical engineer, or are common values that have been published in engineering journals. The procedures to achieve the proper density of a compacted structural fill are dependent on. the size and type of compacting equipment, the number of passes to be made over the soils with the compactor, the thickness of the layer to be compacted, and some properties of the soils, including water content. The density of a soil can sometimes be increased by increasing or reducing the water content of the soil, and using the same compactive effort. Water reduces the friction between soil grains and helps the soils to slide into a more compact condition with the same compactive effort. The value of water to decrease friction, and therefore increase compaction, decreases as the soil grains become larger. Water has very little effect on the compaction of coarse sand and gravel. Dry soils can seldom be compacted to the maximum density determined in the laboratory. A higher compactive effort could achieve the same density with less water, with some limitations. As the water is decreased, the friction between the soil grains increases, and as heavier compactive loads are applied the friction between the soil -grains increases to resist the compactive load from forcing the grains into a more compact condition, therefore at some point of lower water content, the heavier compactive efforts increase the resistance•. to compaction, and nothing is accomplished. If the compactor vibrates, then the friction forces between the soils are temporarily reduced as the load of the compactor is released during the upward motion of the vibration cycle. The soils can then move into a more compact condition during the release, or are forced together as the load is reapplied during the downward motion of the compactor. SPIRO RESIDENCE page 34 of 67 pages More water reduces more friction between the soil grains, but as the water fills the pore spaces between the grains of the loose soils, it takes up some of the space that the soils need to become more compact. With coarse grained soils, such as sand and gravel, the water can be forced out of the pore spaces very quickly as the soils are being compacted, but with fine grained soils, such as clay, silt, and fine sand, the water cannot squeeze out fast enough, and 'it fills the pore space before the soil has compacted to the desired density. The trapped water then becomes a hydraulic piston that supports the loads of the compactor and resists further compaction. That condition is not always obvious with clay and some silty soils, and the only way to know that compaction has not been achieved is to conduct density tests. With some coarse silts and very fine sands, the water is forced into adjacent pore spaces under high pressure as the compactor loads are applied, but when the compactor releases the load as it moves on, the high pressure water is forced back into the just compacted soils, and the soils rise. The observer will see the soils compact and then rise again, an action called pumping. That indicates that the soils are not being compacted because they are too wet. The ability to increase density with compactive effort is limited by the strength of the soils to resist bearing failure. If the compactor is too heavy, or imparts too great an energy, then the soils adjacent to the compactor will shear up around the sides of the compactor, and then the compactor will compact the soils under it, but will loosen the soils adjacent to ft. Density tests can be conducted in the field to determine that the required percent of the density determined by the Modified Proctor test has been achieved. The locations and quantity of tests required to control the' compaction are determined by the geotechnical engineer in accordance with the number of different soils and the soil types, the sizes and types of compacting equipment, the extent of the field supervision, and the results of laboratory and field density tests. Field densitytests are conducted by obtaining samples of the field compacted soils, measuring the volume of the sample by measuring the hole from which the sample was obtained, and then .weighing the sample in its natural condition, and again after drying, to determine the dry unit weight and the water content. Field densities and water contents can.; also- be determined by nuclear devices, but that equipment is only feasible on very large_ projects.. Generally, poorly compacted soils are the result of poor workmanship, or fine .grained soils being too wet, or coarse grain soils being too dry. To achieve the desired properties of a properly prepared structural fill requires the control and guidance of an expert and/or a testing laboratory. If ft is determined that the laboratory and field testing required to control the compaction of the soils is not warranted at this site, then HEMPHILL should observe and approve the compaction procedures, and should verify that the soils have achieved the approximate desired properties. HEM PH I LL SPIRO RESIDENCE page 35 of 67 pages DENSITY REQUIREMENTS of STRUCTURAL FILL Structural fill that will be located beneath the proposed deck footings, the back porch, under paving, or areas where settlement would be undesirable, should be compacted to a density equal to or greater than 95% of the Modified Proctor maximum density (ASTM D-1557) for that particular soil. Structural fill to be used for temporary bearing under grade beams should be compacted to a density equal to or greater than 85% of the Modified Proctor maximum density (ASTM D-1557).. Structural fill that will be used to backfill excavations that will support steps, walks, or driveway paving where settlement would be undesirable, should be compacted to a minimum density equal to or greater than 95% of the Modified Proctor maximum density (ASTM D-1557). Structural fill to raise the site grade but not supporting paving or portions of the structure should be compacted to a density equal. to. or greater than 90% of the Modified .Proctor maximum density (ASTM D-1557). Structural fill that will be for landscaping, and that will not support loads, can be compacted -to a density equal to.or greater than, 85% of the Modified Proctor maximum density to minimize settlement and shifting; and to be fairly stable on slopes less than 1 vertical to 2 horizontal. COMPACTION of BACKFILL ADJACENT to STRUCTURE The only. portion of the structure that will have significant backfill placed against it is the soldier pile wall at the northeast corner of the house. Imported soils might be required adjacent to the structure where drainage is required. The requirements for drainage materials will be described later in this report. Compaction adjacent to the structure should not be conducted until the concrete has cured to an acceptable strength in accordance with the recommendations of the structural engineer. Compaction adjacent to the structure should be accomplished with light hand operated equipment within a distance of the structure equal to the depth of the fill, so that no excessive lateral pressures are applied to the structure. HEAVY EXCAVATING EQUIPMENT SHOULD NEVER BE USED. TO PLACE OR TO COMPACT STRUCTURAL FILL ADJACENT TO THE STRUCTURE. HEMPHI LL N t� V_ LL N Q W in Z W >X. Q U � W '~ I W CC CJ) LLI Q 0 L. 40 O U W W. N fr m � O W O Z c a Q a W im a N 0 0 Z_' Z 0 Q IOL Q L U � X W W (. & cc > c0 0 QU 0 W w N W m D N W Z ¢ a a W Q (L C`m1 �W rJ O aj W EC C O `0W W >- IV �aoit �' .J �=� `01W N 00m mEyO,W .0 19 .tm..a mV� O aa°V �;:E_W9 W W N i OW �cm W N W cc NO1 C W �O 0 C 01 O aO� yL r =.; E r m00 ELT�e�=0 3 Evmm«mo ME E O > mE g y0, )el~-v m r t. 'O W boo. oTm T m a « XMin 'WO E-Q W ,va° m m :` a>m C WC o r am«oa m= c em Oil C4 —' mE31Ea Coo cpmmm 0 -a .II-aJ um 0«CW. ONm«j W C« aW= mW W'O :SE`o� D �a ON 00oo.2 mE 008 >-7 aim m E p> W Ol A o,m «mW y mS ...00 ° a ON O a= W W `Y 9 C V 0 p �E, mw c W L O> — M C 1O t 0.. m Ea m O «0CC• mWECE Ic Ol0 cc cN- O W E `o��m m W oc_ W c i 0 c W W m ='° N aZof o.m V W >U -c Pm°c « .a E mEmroc«•o3W Wa7n- 3a:WW c- Wcm o EE 9p7 0 Wo a-0 W lon0 W� t�aoic ; rN Od1C °iO S 0cEc o W o W ..'a c MO = m m o c— J U NOo.W O -a— E> 0 a 93 W 3 W J y 3=0 mkt 0-0«J JZ O_ 00025 mp J= ram.. _3CL*j «a9�o rT m��WC Om �t mEWa wa 0So2 xx w .- Z— w Sy W «Cm�acc) W Wa 'M wa a'1 mom. L W m.m Q r.J en c 01 «W O W a WC tc- J J_ WC i OJ a E O >O� a7- ° M a mY rL' O� 7 N mC=m ° OW 0-5O' mot .u°i Me 0 W 0 0ra'$ W t. «_«a�i to CO. W rn .0 zin mot 4? MS02 m ym a1 o trnm cW Su00 N ME ro—� 'C 3oA �°d. con3 OD °O _oN -o > Cl— c3 E« -a-0 vw omC2 « cn ` ccio . m.. «o.. Ic T�- W.i C ° av1in mA. WY L COm C`mj, 0 om all ao7.00 v N`C':.-. m >t::.E 0Eo .EpO1 _ m W m Wa. mt= N W 9V cr m an U d u m o cF-v EN o ° m PL m m a$M M 0 Wa— u u W o.8pm mO v �W O W� W N_ LN.c m r tot O«=C ay�'.o W d0 O— W VW7 �WQ� C .��mW «oo•m `o 0=00 Wm ��, m OOam Do NiE c~VQ p Mr1 q W u W C _ nWC,• C m W m N O—mu O-9 L re 01 Omm° cm '0 W `-q Wt CIO Z'_ 0Me= Oq ao COS .0cum «C o �o �o13:5 to01" oo 00 m>3 >=m� � aU, m0C0 mm to o a; .m m M 0 w _ c O C W W No C y m° C m N 0 n 0 � m 0 m W y 0 m Q -1uS0 �° EE rmiow am 0Oma M, C� V Ooa m O� mN VC. O>= W o•Q�q 0IjEMO we E~ W aoyc LOIxW o�W= 7•N t01 3 Oc —W v.W .00 -m ;�YW•xa 0C'E0 cW ID m: Oo oo J° �—' W2 E JW _3 J Wm «JET ;mE 3a 0 V W : rW..m WE 0 0 M W=mO A m °xW CL C m C 0 W3W°. o. a Y a« q W.O.W— W m t 2i M OU W V w.r'3 S- -{�j!O.Or W 17 Ol N Wj = N l°O In S M � 3 W In =ma.5 a a u SPIRO RESIDENCE page 36 of 67 pages SOIL DESIGN PARAMETERS for TEMPORARY FOUNDATIONS The foundations for the main structure will be cast -in -place reinforced concrete piles supported by permanently stable soils, but grade beams; the back porch, the spiral stair, and the deck footings will be placed on the upper potentially unstable soils that are capable of temporary support until a slide occurs. The conditions that will cause the instability might never happen in the lifetime of the proposed house, or . they might only happen on the lower slope. The temporary bearing soils will be prepared as would any permanent soils. PREPARATION of EXISTING SITE SOILS for TEMPORARY FOUNDATIONS 1. All organic soils, roots, and grass or shrubs should be removed from beneath any locations for deck footings or grade beams. 2. If loose or soft soils, or soils other than the approved soils are encountered at the proposed locations of the grade beams and deck _footings, then the excavations should continue to competent soils approved by HEMPHILL, and the footings placed on the competent soils. 3. Soils at the bottom of footing excavations should be probed by HEMPHILL to verify the bearing capacity, and to locate any soft spots. 4. Any soils loosened by the excavating process, or softened by wet conditions, should be hand excavated. Loose and soft soils should not be hand compacted. Irregularities at the bottom of excavations should not be filled. 5. At the contractor's option, and with HEMPHILL's approval, any over -excavations for footings may be backfilled with either lean concrete or structural fill. 6. Unless approved otherwise _by HEMPHILL, any footings that are over -excavated, and that will be backfilled with structural fill, should be excavated beyond the edges of the proposed footing a minimum distance of 1 foot for each 2 feet of over -excavation, as shown in Figure 29. . BEARING CAPACITY of SOILS The upper very fine sandy silt soils and loose gravely sand soils that were recovered during the Standard Penetration Test, and that might be fill, might be capable of supporting loads of 2000 psf after proper preparation, but those soils might not be consistent over the site. The underlying medium dense silty fine sands are also capable of supporting loads of 2000 psf after proper preparation, but those soils might not be consistent over the site. HEMPH ILL SPIRO RESIDENCE page 37 of 67 pages The temporary allowable bearing capacity of the undisturbed soils should not be increased for temporary loadings from earthquake and wind forces, therefore a maximum allowable design bearing capacity would be 1500 psf, and with a total of 2000 psf allowable for dead, live, and temporary wind and seismic forces. Those values are presumptive and should be verified at the time of construction. SETTLEMENT ESTIMATIONS Some settlement can occur resulting from the densification of the upper 17 feet of soils from seismic vibrations. HEMPHILL estimates that the soils could densify an additional 5%, which would cause approximately 9 inches of settlement. Seismic vibrations could also cause liquefaction, and the resulting settlement would be the result of sliding. Liquefaction might not occur if the proposed drainage system is successful in intercepting the source of groundwater under the site. The amount of settlement from sliding. cannot be estimated. There will be no building loads to cause settlement except for the temporary loads from the grade beams until they can support their own weight;- The rockery, the deck footings., and spiral stair, and . the fill for the driveway -might cause some settlement: Any settlement can add drag loads to the piles:thaLwill be discussed in the section on piles. SETTLEMENT of GRADE BEAMS Since the grade beams will not be loaded until the concrete has cured sufficiently to support the building loads (approximately.30 days); then the only loads on the soils from grade beams will be the initial wet weight of the concrete for the grade beams, which will not exceed 600 psf. If the soils are properly prepared, then that bearing should not cause any significant settlement. Most of the settlement from the weight of the grade beams will occur quickly while the concrete is still wet, and any additional settlement will be minimal.. As the flexibility of the concrete decreases during curing, the strength will increase to begin supporting its own loads. Additional flexing from building loads is anticipated by the design and. no further support from the soils is needed. In fact, the grade beams are designed for the soils to slide out from under the grade beams, therefore any additional settlement for seismic or other reasons is of no consequence after the third day of curing. SETTLEMENT of GARAGE SLAB The only portion of the main structure that could be affected by settlement would be the structural garage slab during curing. The east half of .the garage slab will be placed on an excavated surface approximately 10 feet._below the existing ground surface on the east bench. The loads to be exerted by the garage slab during curing will be less than 75 psf. After approximately 7 `days the garage floor will be capable of supporting itself and any settlement will have no affect on the slab. Because of `the strength of the Double Bluff Drift soils, the removal of 10 feet of soil, and the light loads, settlement during curing of the slab is not anticipated. HEMPHI LL o:_.. �...:: o......... ......_ 2 ... .----.... N ._ ..'<a ....... ...... ......... UL : 2 -.. _.. w1_y.._ _ �- ___..___._ __ ' ...... :-......... 1 2 3 4 5 6 DEPTH' BELOW GROUND SURFACE (feet) SPIRO RESIDENCE . page 38 of 67 pages SETTLEMENT of BACK PORCH The back porch will be placed over structural fill compacted to 95% of the Modified Proctor maximum density (ASTM D-1557), therefore minimal settlement will occur, unless there is poor workmanship. Because the structural fill will be supported by a retaining wall that will be into or near stable soils, then HEMPHILL anticipates that a slide will not affect the porch. If, at the time of construction, HEMPHILL determines that a slide could move from under the retaining wall, and that the porch could be undercut, then HEMPHILL will recommend that the porch not be attached. to the house, and that the roof overhang be cantilevered and not supported by columns supported by the porch. SETTLEMENT of DECK & STAIRS Deck and spiral stair footings will be placed on soils capable of supporting loads of 1500 psf with minimal settlement until the soils become unstable. The undisturbed soils and any structural fill will probably settle a similar amount for similar footing sizes and loadings. Figure 30 shows settlement vs bearing vs footing size vs depth of footing. Although off the chart, a loading of 1500 psf placed 1.5 feet below the ground surface with a minimum 18 inch square footing will settle less than 1/4 inch. Deck footings. will probably never be loaded to that capacity. If the deck is partially or completely supported by spread footings to save the cost of a piling foundation system, the amount of settlement to be anticipated cannot be determined because the settlement can range from minimal for compression of the soils while they are stable, to significant for seismic settlement, to extensive for a slide settlement. The deck should be designed for the worst case, which is a complete failure of the spread footing support system. The decks can be designed by any of 4 methods: 1. As a cantilever system supported by the main structure with no bearing on the soils. Research .by HEMPHILL has revealed that cantilevered beams tend to create opposing deflection compared to adjacent non cantilevered beams, and can cause deflection In the outer wall and windows, and can cause distortion of any windows or doors that are parallel to the direction of the cantilevered beams. HEMPHILL has also observed that the distortions can occur over a period of time as the stresses cause creep in the wood structural members. 2. As a cantilever system that can support the dead and live loads, or just the dead loads, and temporary post and footing support to eliminate the deflection. This system might reduce the distortion inside the structure, but the supporting posts and footings can move with any slide or settlement. The posts and footings can be replaced after such movement, or if the settlement is minor, shims can be added between the footing and the post, or between the post and the upper deck structure. The post can be hinged to the.upper structure, or can be connected rigidly to the upper structure and just placed on the footing, allowing the. footing to move from under the post. SPIRO RESIDENCE page 39 of 67 pages 3. As a hinge system connecting at the main structure, with a system of posts and footings. This system requires the post and footing to .support half the deck dead and live loads, and if the footings move with settlement or slide, they can be replaced. The deck must be attached to..the main structure by a hinge system so that any deflection will not distort the main structure, and the deck can be jacked back into place. 4. As a separate structure not attached to the main structure, supported by spread footings and posts. This system can move with settlement or sliding and then can be jacked back into place after any movement. The deck must be light and rigid to be manageable but not extensively damaged. The disadvantage of this system is that there could be differential settlement or separation at the door to the deck. The spiral stair can be hinged where it connects with the deck, .or it can be a free system not connected to the deck or main structure, :otherwise the deck and stairs might damage. each other during a slide failure. DESIGN and PLACEMENT of SPREAD FOOTINGS for DECK & STAIRS Figure 31 shows a plan of the grade beams, and the temporary spread footings for the deck and the spiral stairs. The temporary spread footings will be designed for bearing on the existing soils without concern for future settlement from seismic or, stability failures. OVER -EXCAVATIONS to BEARING SOILS Based on the allowable 1500 psf bearing capacity of the existing soils described as silts and fine sands, if the depth to allowable bearing soils is greater than anticipated, the contractor can choose to over -excavate to bearing soils approved by HEMPHILL, and then to backfill with structural fill or lean concrete to the desired grades of the bottoms of the footings. Any over -excavations of footings required to encounter the, allowable bearing soils which will then be backfilled with structural fill, should be excavated 1 foot wider than the footing for each 2 feet of over -excavation, as shown in Figure 29 on page 36. If allowable bearing soils are not encountered within a reasonable depth, then HEMPHILL can determine the bearing _capacity of the encountered soils, and: can determine the required thickness of structural fill under the footing to dissipate the footing pressure to. the allowable -bearing capacity of those soils, provided that the compressibility of those soils is acceptable. HEM P H I LL f-: P FIGURE 32 LOCATIONS of PILES j ,$ 31 36 35 34 33 32 31 30 29 ---�-z, NIL NOTES: - 1. PILES are NUMBERED for REFERENCE DURING k CONSTRUCTION. 3_ 2 2. SOLDIER PILES in RED (16, 17, 11, 7, 8) are 24' . DIAMETER 3000 psi CONCRETE with W-12-58 STEEL BEAMS PLACED MINIMUM 25' BELOW BOTTOM of WALL 3. INDIVIDUAL PILES UNDER HOUSE SHOWN in BLACK ARE 180 DIAMETER 3000 psi CONCRETE with n W-10-33 STEEL BEAMS. PLACED MINIMUM 30' BELOW BOTTOM of GRADE BEAMS. 4 O 6 4. SOLDIER PILES at REAR of HOUSE are 160 DIAMETER 3000 psi CONCRETE with W-8-28 STEEL BEAMS PLACED MINIMUM of 7.5' & MAXIMUM 11' BELOW EXCAVATED SURFACE. SPACINGS to be DETERMINED AFTER EXCAVATIONS for BENCH have been COMPLETED. s :4 4, ., 7 8 SPIRO RESIDENCE f►Lyillk"ll►ri111A f�:[•T ��Z���T�C `? page 40 of 67 pages The footings can be sized based on the dead and live loads, including wind and seismic, assuming 2000 psf bearing capacity. MINIMUM DEPTH of FOOTINGS MINIMUM DEPTH for BEARING Footings can be placed directly on the existing soils, or on structural fill, that have been approved for bearing by HEMPHILL. MINIMUM DEPTH for FROST PROTECTION Footings should be placed a minimum of 18 inches below the final ground surface to protect against uplift due to frost expansion, or loss of bearing capacity due to softening from thawing conditions.. DESIGN of GRADE BEAMS Grade beams to be adjacent to unheated areas should be placed a minimum of 18 inches below the final ground surface to protect against uplift due to frost expansion, unless the grade beams are designed to resist uplift. At that depth below the existing ground surface HEMPHILL anticipates that the soils can offer the necessary temporary support, which should be verified at the time that the soils are exposed during the excavating process. PILE FOUNDATIONS and RETAINING SYSTEMS Figure 32 shows the locations of all the piles for the project. The piles are numbered for convenient reference during design and construction. There are 3 kinds of piles for the project: INDIVIDUAL PILES - The house will be supported by individual piles, each designed to support itself against the lateral drag forces of sliding soils, and to support the vertical loads of the house. 2. RETAINING WALL PILES. - The partial octagonal.shape shown in red at the northeast corner of the house has exterior reinforced concrete retaining walls that will support the driveway backfill soils. Those walls will be supported by cast in place concrete piles with steel beams extended to the top of the walls. The walls will be supported between the beams, similar to soldier piles. 3. SOLDIER WALL PILES - The rear slope will be protected and supported by a soldier pile wall that _ will be placed prior to excavating the rear bench. HEMPHILL PSpi' i ----------------- L]J L 1 SPIRO RESIDENCE page 41 of 67 pages The piles that support the house are designed based on an allowable deflection of 1 inch rather than a safety against failure. Of course, bending, shear, and vertical support are checked for safety. The chosen piles are the smallest piles that are safe from failure and still within the allowable deflection and stresses. CONSTRUCTION PROCEDURES If the soils are capable of standing open after drilling, 'then the open hole method of placing piles can be used. The hole can be drilled with either a continuous flight auger, or with a short auger. that drills a short distance and then withdraws to spin off the soil: After the hole is drilled and the auger has been withdrawn, the required depth of the hole should be verified by HEMPHILL The steel beam can then be inserted into the hole with the flanges placed parallel with the slope, except for the retaining wall piles, which will be explained later. The hole is then filled with either concrete or grout. If water or muddy soils collect at the bottom of the hole, then the concrete or grout should be pumped into the hole by placing the hose at the bottom of the hole and then withdrawing the hose as the concrete or grout forces the water and mud up the hole. The contractor or 'a representative should be available with a level and rod to control the level of the. concrete, and to place the reinforcing rods that will tie the pile to the grade beam. The advantages of placing reinforced concrete cast -in -place piles by the open hole method are that the soils can be verified, that steel can. be more' -easily centered in the hole, and that the. volume of the concrete is more easily controlled with less waste and cleanup. If some of the borings for piles would collapse if the holes are left open, then HEMPHILL recommends that cast -in -place piles be placed by boring the hole with a continuous flight auger. - A continuous flight auger drills a continuous hole without withdrawing from the hole, therefore the auger temporarily supports the hole from collapsing. The continuous flight auger has a_hole in the center through which grout is pumped as the auger is withdrawn. The grout, which is more dense than the surrounding soils, then supports the hole.' Grout is composed of cement, sand, and water, which is more easily. pumped without clogging, and - which allows steel to be more easily placed. The grout must be pumped. under continuous pressure, and the auger must be withdrawn at the correct speed so that the grout completely fills the void left by the withdrawing, auger. before the surrounding soil squeezes into the hole. If soil squeezes partially into the hole, it will create a narrow undersized section of pile. If soil completely fills a section of the .hole, then the pile will- not be continuous, and the entire pile will be no stronger than the reduced section, and the steel could be exposed to eventual corrosion. The steel beam can then be placed in the grout filled hole after the auger has been completely. withdrawn. If the hole is longer than the steel beam, then the beam will require temporary support until the grout has partially cured. FIGURE 33 DESCRIPTIONS of RESISTING SOILS G R A N U L A R S.0 I L S -------------------------------------------- RELATIVE SOIL STANDARD f DENSITY CONSISTENCY PENETRATION (pci M ------- ----------- (blows/ft) ---------- /ft) --- 0------------------- 0 0 VERY 10 LOOSE ------------------- 4 -5.6 20 LOOSE 30 ------------------- 10 12.7 40 MEDIUM 50 DENSE 60 ------------------- 30 37.0 70 DENSE 80 ------------------- 50 54.5 90 VERY DENSE 100------------------- 70 69.4 NOTES C O H E S I V E S O I L S -------------------------------------------- UNCONF'D SOIL STANDARD f COMPR'SN CONSISTENCY PENETRATION (pci (psf) ------- ----------- (blows/ft) ---------- /ft) --- _ 0------------------- 0 0 VERY SOFT 500------------------- 2 2.3 SOFT 1000------------------- 4 5.6 1500 MEDIUM STIFF 2000------------------- 8 12.7 STIFF 4000------------------- 15 VERY STIFF 8000------------------- 30 HARD 12,000 ------------------- 60 * LATERAL SOIL MODULUS is CONSTANT f = RATE of -CHANGE of SOIL MODULUS with SOIL DEPTH = 50.2 pci/ft v SPIRO RESIDENCE page 42 of 67 pages A disadvantage of drilling with a continuous flight auger is that the soils cannot be observed to verify that the required bearing soils have been encountered. If the bearing soils are much harder .than the overlying soils, then the location of the top of the bearing soils will be obvious by the increased difficulty of drilling. If the bearing soils are not significantly harder, or if the soils are uncemented sands, then the top of the bearing soils might not be obvious. Either previous investigations will have been required to locate the top of the bearing soils, or the piles must be designed to be long enough to assure that the piles are embedded the minimum required depth into the hard clay for both bearing and friction. STRUCTURAL DESIGN of PILES The piles were designed using steel. beams because of the need to retain soils between the piles (soldier piles), and because most contractors opt to use steel beams because of the ease of placement and reduced labor costs. The ability of the piles to resist lateral forces is dependent on the steel beams because the tension side of the concrete is of no value, and because..the bonding between the concrete and the steel beam to transfer bending in questionable. Therefore the lateral forces on the pile are determined by the diameter of the concrete, but the strength of the pile is determined by the steel beam. SOIL DESIGN PARAMETERS for PILES LATERAL RESISTANCE All the piles were designed based on the lower portions of the piles being placed into the hard Whidbey Clay the necessary distance to resist lateral deflection of the piles, which also resists lateral failure of the piles. The resistance to deflection for various soils is shown under the 'f column in Figure 33 which shows the stress/strain rate for granular and cohesive soils with various consistencies. Although the Whidbey Clay is a hard clay, because of the over consolidation HEMPHILL assumed those soils to act more like a dense to very dense granular soil, therefore all the piles are based on f = 50 pci/ft, which is the rate at which the stress/strain increases. At the top of the hard clay 50 psi causes a strain of 1 inch, but at 1 foot lower it requires 100 psi to strain 1 inch, and at 2 feet it takes 150 psi to strain 1 inch, and so on. VERTICAL RESISTANCE The stable Whidbey Clay can offer vertical support on the piles at conservative values of of 6000 psf bearing and 1000 psf friction, therefore an 18 inch pile with 15 feet of embedment into the hard clay can support loads in excess of 80,000 pounds. If a seismic condition causes some settlement of the upper 15 feet of loose soils, then the drag would only be approximately 8000 pounds, assuming an EFP of 40 pcf acting over the area of the pile surface, and with a friction factor of 0.4, all conservative values. HEMPHILL N W J EL J Q D Z qe M w cc �D V U. 3=1 I 0 N W U F U) + 1 cc cn W x 3 O O w x0. n~ o� Hld3a to w -- C7 ---'--`--- O ccO U- J 0C x _ �" U. U o Z LL U) C7 _ ~a + + x 0. O w O z O Z u. LL = Q w x x U 11 (L !n J cc N x LL w N W N zU)00 0 J w p w LL W 11 w 11 z Z COi II a Q U 0 Z Cc U) N O o J C wj J w 0 N J to W ¢ rn n z O ('� Z OJ Z O J w w W U x a Q O O — `o 0 z X U J Q oC Z Z o N o J 0 a ul c O d O cc uJ a -J O PO LL w • J V U U J x LL z O _ .� LL CC N U LL Z O _ •_ 0 U cc u 0 Q w W Fa- = W U. II J W Z � Q O~. ` x ¢ U O Z Z W > J W a Q x U O W Q Q 0 W U F- O w W = U W II ~ 11 °occ OLL V p� 0 x Z 0 Z 0 ¢ t it C I (0 w U LL v j U) II tl V i d, a N a . x U a: It II Q II 11 11 w l9 U Z w 0 O U u� w ti w ti u o C LL J to SPIRO RESIDENCE page 43 of 67 pages LATERAL DRIVING FORCES on PILES The driving soil design parameters for the individual piles are based on a silty sandy soil that has a fairly high strength at the time of failure assuming that the soils are worst at the slide plane and stronger above. The stronger the soils above the slide plane the greater the force exerted on the pile. To presume the soils below the slide plane to be weaker, and the soils above the slide plane to be stronger, presents a more conservative design. The individual piles, so. named because. each pile is independent of other piles, are designed based on the lateral forces of the potential sliding soils sliding past the piles and dragging on the piles and the cone of soil that becomes trapped behind them, as shown in Figure 34. The angle of the cone is similar to the angle of failure under a footing in a bearing failure. Figure 34 shows the pile and the cone, the labels for the forces and dimensions, and the calculations for the lateral force (Ft). The piles are designed based on the sliding soil dragging on the length X + Y on each side of the pile. The friction factor for the sliding soils on the concrete and the sliding soil on the cone is considered to be similar, since if soil sticks to the concrete, then the sliding will occur between that soil and the next layer of soil, otherwise if the friction between the concrete and the soil is less than between the soil layers, then the calculations will be conservative. The shearing force (Fs) is the total of the cohesion and friction forces along X + Y, and the total lateral driving force (Ft) is the resultant of the Fs forces. The friction forces result from the normal force (Fn) from the sliding soils: The normal force can be determined from the estimated equivalent fluid pressure (EFP) of the soils, or it can be calculated using a sliding wedge based on the unit weight, the internal friction, and the cohesion of the soils, plus the worst angle of sliding, to establish the lateral forces of the soils in any direction, including the normal forces along the cone. The worst situation would occur if the soils at the slide surface are weak and the upper soils that drag along the pile are strong, therefore HEMPHILL calculated the lateral forces on the piles based on an Fn determined by an internal friction value of 30 degrees, which gives a large Fn, and based on the friction value + cohesion for the shear along the cone and. the pile, which also gives a high value. HEMPHILL used an EFP of 40 pcf, no cohesion, and an angle of internal friction for the soils of 30 degrees. Those .values are conservative since they give higher drag forces than if the friction factor of 20 degrees were used that corresponds to an EFP of 40 pcf. The Friction factor of 30 degrees calculates to an angle of deflection around the pile of 30 degrees. M uj D 0 U- I 1 i / I I I i i I I U) f I J f } cn � of of z act Q of (n .� cl f of- �I Q W1 I F, Z �I W a _I W+ I o / p z / Q w C, 3 C) w lo W a to QW a}—ZW ¢QZpcc z wZgw o=N>Q = M J LC cnO5p(¢Z Z Q J W 23 Co Q w F- -i W D w CL F- U Z U w CV Ch p z SPIRO RESIDENCE page 44 of 67 pages DESIGN of INDIVIDUAL PILES Figure 35 shows a section of the individual piles with the approximate depths of the piles. The design parameters used by HEMPHILL to design the individual piles, recommended to be an 18 inch diameter concrete pile with a W-10-33 steel beam, are shown on the next page in Figure 36. The pile was chosen based on the bending moment of 49,130 ft Ibs applied by the sliding soils. Also on the next page is Figure 37 which shows the design values for four optional pile lengths. HEMPHILL recommends the 34.5 foot length pile which deflects a maximum of 0.275 inches, has a maximum bending moment of 69,402 ft Ibs, and a maximum shear of 8755 lbs. The maximum bending moment .is slightly larger than the allowable of 69,098, which is insignificant. That pile will be placed a minimum of 17.5 feet into the hard Whidbey Clay. -V FIGURE 36 DESIGN PARAMETERS for INDIVIDUAL PILES A. D E S C R I P T I O N o f P R O J E C T TRIAL NUMBER 3C PROJECT NUMBER 1636 CLIENT is SPIRO FAMILY PILE CALCULATIONS for SPIRO FAMILY HOUSE LOCATION of PILE is UNDER HOUSE B. S L I D E S 0 1 L D A T A a. HEIGHT from GROUND SURFACE to SLIDE SURFACE b. COHESION of SLIDE SOIL - c. ANGLE of INTERNAL FRICTION of SLIDE SOIL d. EQUIVALENT FLUID PRESSURE of SLIDE SOILS e. ANGLE of DEFLECTION of SLIDE SOILS AROUND PILE f. MAXIMUM SHEAR FORCE BETWEEN SLIDING SOILS and CONE g. TOTAL SHEAR FORCE in PILE from SLIDING SOILS h. BENDING MOMENT APPLIED by SLIDE SOILS C. P I LE DATA 1. S T E E L D A T A a. STEEL BEAM DESIGNATION b. AREA of STEEL BEAM c. DEPTH of STEEL BEAM d. WEB THICKNESS of STEEL BEAM e. FLANGE WIDTH of STEEL BEAM f. DIAGONAL DISTANCE ACROSS FLANGES g. MOMENT of INERTIA of STEEL BEAM AROUND xx AXIS h. MODULUS of ELASTICITY of STEEL i. ALLOWABLE BENDING STRESS of STEEL j. ALLOWABLE SHEAR STRESS of STEEL k. ALLOWABLE BENDING MOMENT of STEEL BEAM I. ALLOWABLE SHEAR FORCE of STEEL BEAM 2. C O N C R E T E D A T A a. COVER for STEEL b. DIAMETER of PILE c. ULTIMATE STRENGTH of CONCRETE d. MODULUS of ELASTICITY of COMBINED PILE SECTION e. MOMENT of INERTIA of PILE D. E X T E R N A L F 0 R C E S a. SHEAR FORCE from. -STRUCTURE (from STRUCT. ENGR.) b. TOTAL SHEAR FORCE from SLIDING SOILS + STRUCTURE c. BENDING MOMENT from STRUCTURE (from STRUCT. ENGR.) d. TOTAL BENDING MOMENT from SLIDING SOILS + STRUCTURE 17 ft 0 _psf 30 degrees 40 pcf 30 degrees 5,006 psf 8,670 lbs 49,130 ft lbs W-10-33 9.7 sq in . 9.8 inches 0.3 inches 8.0 inches 12.6 inches 171 'in\4 29,000,000 psi/in/in 23,760 psi 14,500 psi 69,098 ft lbs n 45,188 lbs 2 inches 18 inches 3,000 psi 2,994,102 psi 6,629 in\4 0 lbs 8,670 lbs 0 ft lbs 589,560 in lbs SPIRO RESIDENCE page 45 of 67 pages FIGURE 37 DESIGN of INDIVIDUAL PILES. PROJECT NUMBER 1636 TRIAL NUMBER 3C The DESCRIPTION of the RESISTING SOILS is DENSE GRANULAR The LATERAL SOIL MODULUS (RATE of INCREASE WITH DEPTH).= f = 50.2 pci/ft The STEEL BEAM DESIGNATION is W-10-33 TOTAL LENGTH DEPTH of DEFLECTION (in) BENDING MOMENT (ft lb) SHEAR (lb) LENGTH BELOW INVESTIGATN of PILE ------- ------- SLIP SURF --------- --------- BELOW SLIP --------- --------- MOMENT -------- -------- SHEAR ------- ------- TOTAL ------- ------- MOMENT -------- -------- SHEAR --------- --------- TOTAL --------- --------- MOMENT -------- -------- SHEAR ------- ------- TOTAL ------- ------- MAX ALLOWABLE = 1.000 MAX ALLOWABLE = 69,098 _ MAX ALLOWABLE .= 45,188 25.7 8.7 0.0 +0.261 +0.252 +0.513 +49,130 +0 +490130 +0 +8,670 +8,670 25.7 8.7 2.2 +0.139 +0.189 +0.327 +45,200 +15,146 +60,346 -3,375 +5,202 +1,827 25.7 8.7 4.4 +0.041 +0.094 +0.135 +31,934 +17,797 +49,731 -8,999 -2.167 -11,167 25.7 8.7 6.6 -0.049 +0.000 -0.049 +9,826 +7,573 +17,399 -8,999 -5,809 -14,808 25.7 8.7 8.7 -0.122 -0.094 -0.217 +0 +0 +0 +0 +0 +0 30.1 13.1 0.0 +0.139 +0.163 +0.302 +49,130 +0 +49,130 +0 +8,670 +8,670 30.1 13.1 2.2 +0.057 +0.107 +0.164 +46,673 +17,418 +64,092 -.1,687 +6,936 +5,249 30.1 13.1 4.4 +0.024 +0.063 +0.087 +39,304 +26506 +65,810 -4,500 +1,734 -2,766 30.1 13.1 6.6 +0-.000 +0.031 +0.031 +29,478 +23,855 +53,333 -6,187 -3,034 -9,222 30.1 13.1 8.7 -0.016 +0.000 -0.016 +14,739 +15,146 +29,885 -6,187 -5,202 -11,3891 30.1 13.1 10.9 -0.024 -0.019 -0.043 +4,913 +3;787 +8,700 -4,162 -41+335 -8,497 30.1 13.1 13.1 -0.033 -0.031 -0.064 +0 +0 +0 +0 +0 +0 34.5 17.5 0.0 +0.131 +0.145 +0.275 +49,130 +0 +49,130 +0 +8,670 +8,670 34.5 17.5 2.2 +0.057 +0.094 +0.151 +47,165 +17,418 +64,583 -1,687 +6,936 +5,249 34.5 17.5 4.4 +0.020 +0.050 +0.071 +41,760 +27,642 +69,402 -4,162 `+2,601 . -1,561 34.5 17.5 6.6 +0.000 +0.019 +0.019 +29,969 +28,020 +57,990 -5,287 -1,300 -60568 34.5 17.5 8.7 -0.016 +0.006 -0.010 +19,652 +23,476 +43,128 -5,287 -3,468 -80755 34.5 17.5 10.9 -0.016 -0.006 -0.023 +9,826 +15.,146 +24,972 -4,162 -3,641 -7,804 34.5 17.5 13.1 -0.012 -0.013 -0.025 +1,474 +7,573 +9,047. -2,587 -3,034 -5,622 34.5 17.5 15.3 -0.008 -0.013 -0.021 +491 +1,136 +1,627 -1,125 -1,734 -2,859 34.5 17.5 17.5 -0.004 -0.013 -0.017 +0 +0 +0 +0 +0 +0 38.8 21.8 0.0 +0.131 +0.145 +0.275 +49,130 +0 +49,130 +0 +8,670 +8,670 38.8 21.8 2.2 +0.057 +0.094 +0.151 +47,165 +17,418 +64,583 -1,687 +6,936 +5,249 38.8 21.8 4.4 +0.020 +0.050 +0.071 +41;760 +27,642 +69,402 -4,162 +2,601 -1,561 38.8 21.8 6.6 +0.000 +0.019, +0.019 +291969 +28,020 +57,990 -50287 -1,300 -6,588 38.8 21.8 8.7 -0.016 +0.006 -0.010 +19,652 +23,476 +43,128 -5,287 -3,468 =8,755 38.8 21.8 10.9 -0.016 -0.006 -0.023 +9,826 +15,146 +24,972 -4,162 -3,641 -7,804 38.8 21.8 13.1 -0.012 -0.013 -0.025 +1,965 +7,573 +9,538 -2,587 -3,034 -5,622 38.8 21.8 15.3 -0.008 -0.013 -0.021 -1,474 +2,651 +1;177 -1,125 -1,734 -2,859. 38.8 21.8 17.5 -0.004 -0.013 -0.017 -2,456 +757 -1,699: +0 -867 -867 38.8 21.8 19.7 +0.000 +0.000 +0.000 +0 +0 +0 ..+337 +0 +337 H E M P H I LL FIGURE 38 RETAINING WALL PILE DESIGN PARAMETERS D E S C R I P T I O N o f P R O J E C T CALCULATION TRIAL NUMBER 2A PROJECT NUMBER- 1636 CLIENT is SPIRO FAMILY PILE CALCULATIONS for SPIRO FAMILY HOUSE LOCATION of SOLDIER PILE WALL is at NORTHEAST CORNER of HOUSE S O I L D A T A ACTIVE SOIL DESCRIPTION.(BEHIND SOLDIER PILE WALL) is GRANULAR STRUCTURAL FILL RATE of CHANGE of SOIL MODULUS M = 50 pci/ft ESTIMATED EQUIVALENT FLUID•PRESSURE of SOILS BEHIND WALL = 30 pcf GAP BETWEEN LAGGING and TOP of LATERAL RESISTING SOILS = 15 ft RANGE of WALL HEIGHT THAT SUPPORTS LATERAL FORCES = 7 to 9 ft P I L E D E S I G N D A T A S T E E L S E C T I O N A. STEEL BEAM SECTION PROPOSED for SOLDIER PILES _ W-12-58 B. MOMENT of INERTIA of STEEL BEAM SECTION (X AXIS) = 476 in\4 C. MOMENT of INERTIA of STEEL BEAM SECTION (Y AXIS) = 107 in\4 D. DEPTH of STEEL BEAM = 12.2 in E. FLANGE WIDTH of STEEL BEAM = 10.0 in F. THICKNESS of WEB of STEEL BEAM = 0.4 in G. MODULUS of ELASTICITY of.STEEL = 29,000,000 psi/in/in H. MAXIMUM ALLOWABLE BENDING STRESS in STEEL BEAM = 24,000 psi I. MAXIMUM ALLOWABLE SHEAR STRESS in STEEL BEAM =. 14,500 psi J. MAXIMUM ALLOWABLE LATERAL DEFLECTION of STEEL PILE = 1.000 in C O N C R E T E S E C T I O N K. DIAGONAL DISTANCE ACROSS STEEL SECTION = 15.8 inches L. MINIMUM PROTECTIVE COVER for STEEL = 2.0 inches M. DIAMETER of CONCRETE SECTION of PILE = 20 inches N. MODULUS of ELASTICITY of CONCRETE = 3,000,000 psi 0. ULTIMATE STRENGTH of CONCRETE = 3,000 psi C O M B I N E D S E C T I O N P. MODULUS of ELASTICITY used for COMBINED PILE SECTION = 3,000,000 psi G. MOMENT of INERTIA USED for COMBINED SECTION of PILE = 12,125 in\4 SPIRO RESIDENCE page 46 of 67 pages RETAINING WALL PILES Figure 32 on page 40 shows the locations of the retaining foundation walls and piles in red, which will include piles 8, 7, 11, 17, and 16. Although Pile 4 will help to support the retaining wall, it will not be designed as a retaining wall pile. Pile 4 will not be designed for lateral soil pressures on the wall because the fill soils range from 1 to 4 feet along the half of wall between Piles 4 and 8 supported by Pile 4. The walls will be similar to a soldier pile .wall supported at the base by lateral resisting piles constructed with steel beams encased in concrete. The steel beams then extend above the concrete encasing to support the reinforced concrete wall. The wall is constructed by welding the horizontal reinforcing steel to the webs of the steel beams, except for Pile 4 which will be designed as an individual pile, and the steel for the retaining wall will be welded to the flange. Piles 8 and 17 should be turned 45 degrees so -that the wall steel will be welded to the webs. That will cause the components of the backfill forces from. the adjacent walls to be perpendicular to the flange, which is the direction of the design of the piles to resist the permanent backfill soils. The direction parallel to the flanges can still resist the potential sliding soils. Pile 11 can be turned 22.5 degrees, and pile 11 can be turned 67.5 degrees, from the directions that the numbers show on Figure 32. Pile 16 will only support half the wall between Piles 16 and. 17, but since that is a long wall (10 ft) the. pile size will not be reduced. The retaining foundation walls will always be supporting.the backfill soils for the driveway, therefore the flanges of the beams will be perpendicular to the direction of the lateral forces from the backfill soils. If a slide should occur;it will occur more downslope to the west, therefore perpendicular to the forces from the backfill soils. HEMPHILL determined that the piles must be designed to resist the permanent loads of the backfill soils against the retaining wall, plus the temporary loads of sliding soils against the piles themselves acting perpendicular to the retaining wall loads; therefore the piles must be designed with a steel beam that has a high moment of inertia around the Y axis. The design parameters, described below, that are used to design the retaining wall piles (W-12-58) are shown in Figure 38. The same design parameters were used to check those piles for soil drag along the pile perpendicular to the wall forces, which would bend the pile around the Y axis, except the flange width and the beam depth were reversed, and the Y axis moment of inertia of 107 in4 was used. LATERAL DRIVING PRESSURES on RETAINING WALLS The lateral driving pressures against the retaining walls will exist regardless of any sliding of the lower soils. HEMPHILL assumed the lateral driving pressures against the retaining foundation wall to be the result of well placed structural fill, and based on a soil with no cohesion and an internal friction factor- of. 0.5, also defined as 26.5 degrees, which is approximately equal to 30 pcf equivalent fluid pressure. HEMPHILL FIGURE 39 DESIGN of RETAINING WALL PILES IRO FAMILY HOUSE PROJECT NUMBER 1636 TRIAL NUMBER 2A a DESCRIPTION of the DRIVING SOILS is GRANULAR STRUCTURAL FILL e DESCRIPTION of the RESISTING SOILS is DENSE GRANULAR r e LATERAL SOIL MODULUS (RATE of INCREASE WITH DEPTH) = f = 50.2 pci / ft ,.. e STEEL BEAM DESIGNATION is W-12-58 r IGHT SPACING TOTAL LENGTH DEPTH DEFLECTION (in) BENDING MOMENT (ft lb) SHEAR (lb) ofof LENGTH BELOW from -------------------------- ------------------------------- -----------------=- ALL ---- I PILES ------- of PILE ------- SURFACE ------- SURFACE ------- MOMENT -------- SHEAR ------- TOTAL ------- MOMENT --------- SHEAR ------------------ TOTAL MOMENT -------- SHEAR ------- TOTAL ------- i MAX ALLOWABLE = 1.000 MAX ALLOWABLE = 156,194 MAX ALLOWABLE = 63,455 7 8 35 13.4 0.0 +0.163 +0.064 +0.227 +101,920 +0 +101,920 +0 +5,880 +5,880 7 8 35 13.4 2.2 +0.067 +0.042 +0.109 +96,824 +12,039 +108,863 -3,435 +4,704 +11269 7 8 35 13.4 4.5 +0.029 +0.025 +0.053 +81,536 +18,321 +99,857 -9,159 +1,176 -7,983 7 8 35 13.4 6.7 +0.000 +0.012 +0.012 +61,152 +16,489 +77,641 -12,594 -2,058 -14,652 7 8 35 13.4 8.9 -0.019 +0.000 -0.019 +30,576 +10,469 +41,045 -12,594 •-3,528 -16,122 7 8 35 13.4 11.1 -0.029 -0.007 -0.036 +10,192 +2,617 +12,809 -8,472 -2,940 -11,412 7 8 35 13.4 13.4 -0.038 -0.012 -0.051 +0 +0 +0 +p +0 +0 7 9 35 13.4 0.0 +0.183 +0.072 +0.256 +114,6160 +0 +114,660 +0 +6,615 +6,615 7 9 35 13.4 2.2 +0.076 +0.047 +0.123 +108,927 +13,544 +122,471 -3,864 +5,292 +1,428 7 9 35 13.4 4.5 +0.032 +0.028 +0.060 +91,728 +20,611 +112,339 -10,304 +1,323 -8,981 7 9 35 13.4 6.7 +0.000 +0.014 +0.014 +68,796 4.18,550 +87,346 -14,168 -2,315 -16,483 7 9 35 13.4 8.9 -0.022 +0.000 -0.022 +34,398 +11,778 +46,176 -14,168 -3,969 -18,137 7 9 35 13.4 11.1 -0.032 -0.008 -0.041 +11,466 +2,944 +14,410 -9,531 -3,308 -12,839 7 9 35 13.4 13.4 -0.043 -0.014 -0.057 +0 +0 +0 +0 +0 +0. 8 8 36 13.4 0.0 40.217 +0.084 +0.301 +135,680 +0 +135,680 +0 +7,680 +7,680 8 8 36 13.4 2.2 +0.089 +0.055 +0.144 +128,896 +15,725 +144,621 -4,572 +61144 +1,572 8 8 36 13.4 4.5 +0.038 +0.032 +0.070 +108,544 +23,929 +132,473 -12,193 +1,536 -10,657 8 8 36 13.4 6.7 +0.000 +0.016 +0.016 +81,408 +21,536 +102,944 -16,765 -2,688 -19,453 8 8 36 13:4 8.9 -0.026 +0.000 -0.026 +40,704 +13,674 +54,378 -16,765 -4,608 -21,373 8 8 36 13.4 11.1 -0.038 -0.010 -0.048 +13,568 +3,418 +16,986 -11,278 -3,840 -15,118 8 8 36 13.4 13.4 -0.051 -0.016 -0.067 +0 +0 +0 +0 +0 +0 8 9 36 13.4 0.0 +0.244 +0.094 +0.338 +152,640 +0 +152,640 +0 +8,640 +8,640 8 9 36 13.4 2.2' +0.101 +0.062 +0.162 +145,008. +17,691 +162,699 -5,144 +6,912 +1,768 8 9 36 13.4 4.5 +0.043 +0.036 +0.079 +122,112 +26,920 +149,033 -13,717 +1,728 -11,989 8 9 36 13.4 6.7 +0.000 +0.018 +0.018 +91,584 +24,228 +115,812 -18,861 =3,024 -21,885 8 9 36 13.4 8.9 -0-029 +0.000 -0.029 +45J92 +15,383 +61,175 -18,861 -5,184 -24,045 8 9 36 13.4 11.1 -0.043 -0.011 -0.054 +15,264 +3,846 +19,110 -12,688 -4,320 -17,008 8 9 36 13.4 13.4 -0.057 -0.018 -0.076 +0 +0 +0 +0 +0 +0 9 8 37 13.4 0.0 +0.280 +0.106 +0.386 +174,960 +0 +174,960 +0 +9,720 +9,720 9 8 37 13.4 2.2 +0.115 +0.069 +0.184 +166,212 +19,902 +186,114 -5,896 +7,776 +1,880 9 8 37 13.4 4.5 +0.049 +0.041 +0.090 +139,968 +30,286 +170,254 -15,723 +1,944 -13,779 9 8 37 13.4 6.7 +0.000 +0.020 +0.020 +104,976 +27,257 +132,233 -21,619 -3,402 -25,021 9 8 37 13.4 8.9 -0.033 +0.000 -0.033 +52,488 +17,306 +69,794 -21,619 -5,832 -27,451 9 8 37 13.4 11.1 -0.049 -0.012 -0.062 +17,496 +4,327 +21,823 -14,544 -4,860 -19,404 9 8 37 13.4 13.4 -0.066 -0.020 -0.086 +0 +0. +0 +0 +0 +0 SPIRO RESIDENCE page 47 of 67 pages The greatest possible total moment on the retaining foundation wall piles was determined based on a space of 15' between the bottom of the wall and the hard lateral resisting clay, which is the worst possible condition, therefore the maximum possible moment on the pile is: 1[(30 pcf x 9' height2) / 21 x 8' wide} x 18' lever = 175,000 ft Ibs The lever arm used was for a 9 foot wall and is the sum of 15 feet from the top of the hard clay to the base of the excavated crawl space (bottom of the wall) plus 3 feet to the centroid of the lateral forces from the non -cohesive soils against the wall. DESIGN.of RETAINING WALL PILES Figure 39 shows the calculated values for deflection, bending moment, and shear resulting from . both moment and shear, and then shows the totals. Those values are shown at several different positions on the piles from the top of the hard clay. Figure 39 shows 5 different wall height and pile spacing combinations, then shows the total length of the pile from the bottom of the wall, then the depth into the hard clay, and then shows the depth into the clay that is being investigated. The total length of pile of approximately 35 to 37 feet will be used, with 13.4 feet of embedment into the hard clay. Figure 40 on the next page shows the calculations to check the deflection, bending, and shear of the retaining wall piles around the Y axis caused by the drag of the sliding soils. DEFLECTION of the PILES The deflections shown in Figure 39 would be for a situation where the upper unstable soils had slid. Prior to that time, if ever, the upper soils will help to resist deflection of the piles from loads on the walls. Therefore the deflections shown in Figure 39 will actually exist if the upper soils should creep around the piles, but otherwise will not occur until sliding occurs, and then only N the driveway soils do not also slide. The deflections shown in Figure 40 result from drag of the potential sliding soils acting to the west and perpendicular to the web of the beam in the pile. The deflections shown are at the top of the clay, and then they extend up to the house, but projections show that the deflections are still less than the allowable 1 inch. HEMPHILL FIGURE 40 SLIDE FORCES on RETAINING WALL PILES PROJECT NUMBER 1636 TRIAL NUMBER 3E The DESCRIPTION of the RESISTING SOILS is DENSE GRANULAR The LATERAL SOIL MODULUS (RATE of INCREASE WITH DEPTH) = f = 50.2 pci/ft The STEEL BEAM DESIGNATION is W-12-58 TOTAL -LENGTH DEPTH of DEFLECTION (in) BENDING MOMENT (ft Ib) SHEAR (1b) LENGTH BELOW INVESTIGATN of PILE SLIP SURF BELOW SLIP MOMENT SHEAR TOTAL MOMENT SHEAR TOTAL MOMENT SHEAR TOTAL MAX ALLOWABLE = 1.000 MAX ALLOWABLE = 42,313 MAX ALLOWABLE = 52,128 24.2 9.2 0.0 +0.126 +0.146 +0.272. +28,125 +0 +28,125 -.. +0 +5,625 +5,625 24.2 9.2 2.3 +0.067 +0.109 +0.177 +25,875 +10,392 +36,267 -1,827 +3,375 +1,548 24.2 9.2 4.6 +0.020 +0.055 +0.074 +18,281 +12,211 +30,492 -4,871 -1,406 -6,278 24.2 9.2 6.9 -0.024 +0.000 -0.024 +5,625 +5,196 +10,821 -4,871 -3,769 -8,640 24.2 9.2 9.2 -0.059 -0.055 -0.114 +0 +0 +0 +0 +0 +0 28.9 13.9 0.0 +0.067 +0.095 +0.162 +28,125 +0 +28,125 +0• +5,625 +5,625 28.9 13.9 2.3 +0.028 +0.062 +0.090 +26,719 +11,951 +38,670 -913 +4,500 +3,587 28.9 13.9 4.6 +0.012 +0.036 +0.048 +22,500 +18,186 +40,686 -2,436 .+1,125 -1,311 28.9 13.9 6.9 +0.000 +0.018 +0.018 +16,875 +16,368 +33,243 -3,349 -1,969 -5,318 28.9 13.9 9.2 -0.008 +0.000 -0.008 +8,438 +10,392 +18,830 -3,349 -3,375 -6,724 „ 28.9 13.9 11.5 -0.012 -0.011 -0.023 +2,813 +2,598 +5,411 -2,253 -2,813 -5,066 28.9 13.9 13.9 -0.616 -0.018 -0.034 +0 +0 +0 +0 +0 +0 33.5 18.5 0.0 +0.063 +0.084 _ +0,147 +28,125 +0 +28,125 +0 +5,625 +5,625 33.5 18.5 2.3 +0.028 +0.055 +0.082 +27,000 +11,951 +38,951 -913 +4,500 +3,587 33.5 18.5 4.6 +0.010 +0.029 +0.039 +23,906 +18,966 +42,872 -2,253 +1,688 -566 33.5_ 18.5 6.9 +0.000 +0.011 +0.011 +17,156 +19,226 +36,382 -2,862 -844 -3,706 33.5 18.5 9.2 -0.008 +0.004 -0.004 +11,250 +16,108 +27,358. -2,862 -2,250 -5,112 33.5 18.5 11.5 -0.008 -0.004 =0.012 +5,625 +10,392 .+16,017 -2,253 -2,363 -4,616 33.5 18.5 13.9 -0.006 -0.007 -0.013 +844 +5,196 +6,040 -1,401 -1,969 -3,369 33.5 18.5 16.2 -0.004 -0.007 -0.011 +281 +779 +1,061 -609 -1,125 -1,734 33.5 18.5 18.5 -0.002 -0.007 -0.009 +0 +0 +0 +0 +0 +0 38.1 23.1 0.0 +0.063 +0.084 +0.147 +28,125 . +0 +28,125 +0 +5,625 +5,625 38.1 23.1 2.3-.' +0.028 +0.055 +0.082 +27,000 +11,951 +38,951 -913 +4,500 +3,587 38.1 23.1 4.6 +0.010 +0.029 +0.039 +23,906 +18,966 +42,872 -2,253 +1,688 -566 38.1 23.1 6.9 +0.000 +0.011 +0.011 +17,156 +19,226 +36,382 -2,862 -844 -3,706 - 38.1 23.1 9.2 -0.008 +0.004 -0.004 +11,250 +16,108 +27,358 -2,862 -2,250 -5,112 38:1 23.1 11.5 -0.008 -0.004 -0.012 +5,625 +10,392 +16,017 -2,253 -2,363. -4,616 38.1' 23.1 13.9 -0.006 -0.007 -0.013 +1,125 +5,196 +6,321 -1,401 -1,969 -3,369 38.1 23.1 16.2 -0.004 -0.007 -0.011 -844 +1,819 +975 -609 -1,125 -1,734 38.1 23.1 18.5 -0.002 -0.007 -0.009 -1,406 +520 -887 +0 -563 -563 38.1 23.1 20.8, +0.000 +0.000 +0.000 +0 +0 +0 +183 +0 +183 SPIRO RESIDENCE BENDING of the PILES page 48 of 67 pages The bending moment of the piles shown in Figure 39 for various heights of soil against the walls, for various spacing of the piles, and at various depths along the piles, show that the actual bending moment does not exceed the allowable ' except for the 9 foot . high wall with 8 foot spacing, but the maximum bending moment of 186,114 ft Ibs still has a safety factor of 1.3 even with the conservative soil.values used by HEMPHILL Figure 40 shows the bending moments around the Y axis. Although the total length of pile of 28.9 could be used, the length of 35 to 37 feet is required for resisting the wall loads, therefore the depths for sliding loads will be more conservative. The maximum bending moment will be 42,872 ft Ibs, which exceeds the allowable of 42,313 ft Ibs, but the difference is insignificant. RESISTANCE to OVERTURNING The overturning of the retaining foundation wall will be resisted by the rigidity of the wall and the pile system, and possibly. by the resistance of the upper structure against the wall 9 so designed by the.structural engineer. VERTICAL SUPPORT The more than 3 sf area at the end of the pile will give an end bearing force of approximately 20,000 pounds. 'Each additional V of pile placed into the Whidbey Clay. will offer a force of approximately 6,000 pounds of friction, for a total of 80,000 pounds for 10' of embedment, which far exceeds the required vertical support. PRECAUTIONS for CONTRACTOR -Generally, any damage to foundation walls and adjacent structures occurs at the time of construction because of poor construction practices. Compaction adjacent to the foundation walls should not be conducted until the concrete has cured to an acceptable strength. in accordance with the recommendations of the structural engineer, or 30 days with normal concrete, and 7 days with high early concrete. Compaction adjacent to the foundation walls should be accomplished with light hand operated equipment within a distance of the. outside of the foundation wall equal to the height of the fill, so that no excessive lateral pressures are applied to the structure. The fill should be placed in layers no thicker than 8' after compaction to achieve proper compaction, and to reduce lateral pressures on the wall from loose soil. HEAVY. EXCAVATING EQUIPMENT SHOULD NEVER BE USED TO PLACE OR TO COMPACT STRUCTURAL FILL ADJACENT TO STRUCTURES. 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LLJ -i -i — Ui >_ a Q Lij — W U) m _j -1 0 (D ca .......... 3: -1 F- LU (D 0: V) al o ¢ = -i al Lu m ui S u F- 0- CL _J _J LU ........... _j LL W o > Lu LLI Lu -1 0 -i z < S = U -j m of Q. _j U < — CL (f) LLJ M LLJ _J 0 X U_ LL _J Of CL X. LLJ W M > 0- U_ 1=3 LU 0 0 CL M < X. co u Cl LU LL SPIRO RESIDENCE page 49 of 67 pages DESIGN of SOLDIER PILE WALL The soldier pile wall, located as shown in Figure .32 on. page 40, and shown in section in Figure 41, will support the rear slope after the excavations have been conducted for the garage and the driveway. The soldier piles will be placed prior to the excavating process to protect the slope from.sliding after the toe of the slope has been removed. HEMPHILL assumed that the piles for the soldier pile wall will be placed into the hard clay with. no other soils below the bottom of the excavation, therefore the entire length of the supporting sections of the piles will be in stable soils. Figure 42 shows the process for constructing a soldier pile wall, including the 90 degree turn at the south end of the wall. FIGURE 41 SECTION of SOLDIER PILE WALL HEMPHILL FIGURE 44 DESIGN of SOLDIER PILE WALL -IRO FAMILY HOUSE PROJECT NUMBER 1636 TRIAL NUMBER 7 e DESCRIPTION of the DRIVING SOILS is STRUCTURAL FILL & SLOPE SLOUGH e DESCRIPTION of the RESISTING SOILS is DENSE GRANULAR ;e LATERAL SOIL MODULUS (RATE of INCREASE WITH DEPTH) = f = 50.2 pci / ft ,e STEEL BEAM DESIGNATION is W-8-28 -- II'IGHT- SPACING TOTAL LENGTH DEPTH DEFLECTION (in) BENDING MOMENT (ft Lb) SHEAR (Lb) ofof LENGTH BELOW from ------------------°------- ------------------------------- -------------------------- TALL ---- PILES ------- of PILE SURFACE SURFACE MOMENT SHEAR TOTAL MOMENT SHEAR TOTAL MOMENT SHEAR TOTAL MAX ALLOWABLE = 2.000 MAX ALLOWABLE- = 48,536 MAX ALLOWABLE = 33,308 6 10 14 7.5 0.0 +0.068 +0.159 +0.227 +10,800 +0 +109800, +0 +5,400 +5,400 _. 6 10 14 7.5 1.9 +0.036 +0.119 +0.156 +9,936 +8,103 +18,039 . -864 +3,240 +2,376 6 10 14 7.5 3.8 +0.011 +0.060 +0.070 +7,020 +9,521 +16,541 -2,303 -1,350 -3,653 6 10 14 7.5 5.6 -0.013 +0.000 -0.013 +2,160 +4,051 +6,211 -2,303 -3,618 -5,921 6 10 14 7.5 7.5 -0.032 -0.060 -0.092 +0 +0 +0 +0 +0 +0 7 10 15 7.5 0.0 +0.108 +0.217 +0.325 +17,150 +0 +17,150 +0 +7,350 +7,350 7 10 15 7-5 1.9 t0.057 +0.163 +0.220 +15,778 +11,029 +26,807 -1,372 +4,410 +3,038 7 10 15 7.5 3.8 +0.017 +0.081 +0.098 +11,148 +12,959 +24,107 -3,657 -1,838 -5,495 7 10 15 7.5 5.6 -0.020 +0.000 -0.020 +3,430 +5,514 +8,944 -3,657 -4,925 -8,582 7 10 15 7.5 7.5 -0.051 -0.081 -0.132 +0 +0 +0 +0 +0 +0 III 8 10 16 7.5 0.0 + 0.161 + 0.283 + 0.444 + 25,600 + 0 '+ 25,600 +0 +9 600 +9 600 , 8 10 16 7.5 1.9 _ +0.086 +0.212 +0.298 +23,552 +14,405 +37,957 -2,047 +5,760 +3,713 8 10 16 7.5 3.8 +0.025 +0.106 +0.131 +16,640 +16,926 +33,566 -5,459 -2,400 -7,859 8 10 16 7.5 5.6 -0.030 +0.000 -0.030 +5,120 +7,203 +12,323 -5,459 -6,432 -11,891 8 10 16 7.5 7.5 -0.075 -0.106 -0.182 +0 +0 +0 +0 +0 +0 9 8 20 . 11.3 0.0 +0.097 +0.186 +0.284 +29,160 +0 +29,160 +0 +9,720 +9,720 9 8 20 11.3 1.9 +0.040 +0.122 +0.162 +27,702 +16,773 +44,475 -1,166 +7,776 +6,610 9 8 20 11.3 3.8 +0.017 +0.072 +0.089 +23,328 +25,524 +48,852 -3,109 +1,944 -1,165 9 8 20 11.3 5.6 +0.000 +0.036 +0.036 +17,496 +22,972 .+40,468 -4,275 -3,402 -7,677 9 8 20 11.3 7.5 -0.011 +0.000 -0.011 +8,748 +14,585 +23,333 -4,275 -5,832 -10,107 9 8 20 11.3 9.4 -0.017 -0.021 -0.039 +2,916 +3,646 +6,562 -2,876 -4,860 -7,736 9 8 20 11.3 11.3 -0.023 -0.036 -0.059 +0 +0 +0 +0 +0 +0 10 6 21 11.3 0.0 +0.100 +0.173 +0.273 +30,060 +0 +30,000 +0 +9,000 +9,000 10 6 21 11.3 1.9 +0.041 +0.113 +0.154 +28,500 #15,531 +44,031 -1,200 +7,200 +6,000 10 6 21 11.3 3.8 +0.018 +0.066 +0.084 +24,000 +23,633 +47,633 -3,199 +1,800 -1,399 10 6 21 11.3 5.6 +0.000 +0.033 +0.033 +18,000 +21,270 +39,270 -4,398 -3,150 -7,548 10 6 21 1.1.3 7.5 -0.012 +0.000 -0.012 .+9,000 +13,505 +22,505 -4,398 -5,400 -9,798 10 6 21 11.3 9.4 -0.018 -0.020 -0.038 +3,000 +3,376 +6,376 -2,959 -4,500 -7,459 10 6 21 11.3 11.3 -0.024 -0.033 -0.057 +0 +0 +0 +0 +0 +0 SPIRO RESIDENCE page 50 of 67 pages Figure 43 shows the parameters used to design the soldier pile wall, which included lateral forces based on an equivalent fluid pressure of 30 pcf, a wall height that ranges from 6 to 10 feet, no gap between the bottom of the wall and the hard soils, and spacings between piles ranging from 6 to 10 feet. The chosen pile W-8-28 was for its wide flange, and the ability to support a 10 foot high wall with 6 foot spacings, a 9 foot high wall with 8 foot spacings, and an 8 foot wall with 10 foot spacings, as shown in Figure 44 on the opposite page. FIGURE 43 SOLDIER PILE DESIGN PARAMETERS S O I L D A T A ACTIVE SOIL DESCRIPTION (BEHIND SOLDIER PILE WALL) is STRUCTURAL FILL & SLOPE SLOUGH RATE of CHANGE of SOIL MODULUS.M = 50 pci/ft ESTIMATED EQUIVALENT FLUID PRESSURE of SOILS BEHIND WALL = 30 pcf GAP BETWEEN LAGGING and TOP of LATERAL RESISTING SOILS = 0 ft RANGE of WALL HEIGHT THAT SUPPORTS LATERAL FORCES = 6 to 10 ft P I L E . D E S I G N D A T A S T E E L S E C T I O N A. STEEL BEAM SECTION PROPOSED for SOLDIER PILES B. MOMENT of INERTIA of STEEL BEAM SECTION (X AXIS) C. MOMENT of INERTIA of STEEL BEAM SECTION (Y AXIS) D. DEPTH of STEEL BEAM E. FLANGE WIDTH of STEEL BEAM . F. THICKNESS of WEB of STEEL BEAM G. MODULUS of ELASTICITY of STEEL H. MAXIMUM ALLOWABLE BENDING STRESS in STEEL BEAM I. MAXIMUM ALLOWABLE SHEAR STRESS in STEEL BEAM J. MAXIMUM ALLOWABLE LATERAL DEFLECTION of STEEL PILE CONCRETE SECTION. W-8-28 98 in\4 = 22 in\4 8.1 in 6.5 in = 0.3 in = 29,000,000 psi/in/in 24,000 . psi 14,500 psi 2.000 in K. DIAGONAL DISTANCE ACROSS STEEL SECTION = 10.4 inches L. MINIMUM PROTECTIVE COVER for STEEL = 2.0 inches M. DIAMETER of CONCRETE SECTION of PILE = 16 inches N. MODULUS of ELASTICITY of CONCRETE _, 3,000,000 psi 0. ULTIMATE STRENGTH of CONCRETE = 3,006 psi C O M B I N E D S E C T I O N P. MODULUS of ELASTICITY used for COMBINED PILE SECTION = 3,000,000 psi Q. MOMENT of INERTIA USED for COMBINED SECTION of PILE = 4,124 in\4' HEMPHILL Q m m m Cl) m W �- � W Q W cc z°M U LL� U J o U o. Q Z W U w- O ix p a 1 A I m NCC �J Z p J � Z W fA Q CC CC O Q } ccZ 00 m. a U LL 0 0- W Q W aZ Q CC U.Q Q w UN C7 o p o U. !-- iq n p Z a O ga. CC a � c U Z > w CC W (5 W U. J U J Z et SPIRO RESIDENCE page 51 of 67 pages CONCRETE GARAGE FLOOR SLAB PREPARATION of BASE COURSE for GARAGE FLOOR SLAB The east half of the garage floor slab will be placed over the excavated soils. Since it has been determined that there is a source of moisture that could be conducted by capillary action to. contact the underside of the garage floor slab, then the floor slab should be underlain by a capillary break to stop the capillary water. Figure 45 shows an example of a capillary break. Capillary water can create dampness at the surface of the garage floor which will penetrate any boxes, paper, or wood materials, and will rust any metal placed on the floor. PROTECTION of GARAGE FLOOR SLAB from CAPILLARY WATER A capillary break is a soil that will not conduct capillary water to the underside of the garage floor slab. The source of capillary water could be either the groundwater table or surface drainage. Different soils. have different maximum heights'of capillary rise, therefore the effectiveness of a. soil as a capillary break depends on the capillarity of the soil and the height from the water source to the floor slab. HEMPHILL has. determined that the existing soils are not an effective capillary break, therefore the garage floor slab should be underlain by a capillary break composed of a 4 inch layer of aggregate. with a minimum size equal to. approximately 1/4 inch. It might be necessary for the capillary break to be. underlain by a filter or filter soil to prevent the, integrationof the underlying soils and the capillary break aggregates. If required, then the proper. filter soil or. material -should be determined by HEMPHILL in accordance with the available materials at the time of construction. A plastic vapor barrier can be placed on top of the capillary break aggregate to . prevent the condensation of. vapor on the underside of the concrete floor slab. The. plastic will also prevent the loss of water from the bottom of the slab during the curing, process to minimize differential curing, provided that the loss of water. is also preventedfrom the top of the slab. The lower the water/cement ratio of the floor slab concrete, and the longer the concrete is properly. cured, the: stronger the concrete will be, the more, resistantthe slab will be to moisture, and the concrete will.be more resistant to cracking from both curing shrinkage and temperature changes. Because the garage floor is a structural slab,. the proper water cement ratio must be maintained, and -the cement finishers must not add excessive water to reduce their labor. Also, a lower water/cement ratio gives the cement finishers less water to work to the surface, which then gives a'more wear resistant surface, and allows less differential shrinkage between the top and bottom surfaces of the slab, and therefore less spider web cracks. FIGURE_46_ LOCATION of ROCKERY i _ .Q _ - 41 20 k Ids= NO IN -AV ' t r 40 i i ol ol 1 t —. � yroyoe Ill's a Kx ' -All Al • F,F I A 110 D/.Q SPIRO RESIDENCE page 52 of 67 pages ROCKERY DESIGN and CONSTRUCTION LOCATION of ROCKERY The proposed rockery will support the driveway and will act as an extension of the wall between piles 16 and 17, located as shown in Figure 46. 3 METHODS of FAILURE of ROCKERIES 1. SLIDING BETWEEN ROCKS The lateral pressures behind the rockery caused by the soils that the rockery is supporting are resisted by the friction forces between the rocks. The friction forces are determined by the weight of all the rocks above. The greater the weight of the rocks above an intersection between 2 rocks, the greater the friction force at that intersection that will resist sliding. The resistance to sliding can be increased by tipping the rockery back so that the upper rock must slide uphill on the lower rock. The resistance can also be increased by wedging the rocks so that. peaks and valleys are interlocked. That value cannot be considered in the design of a rockery because it is dependent on the shape of the rocks and the way that the rocks are placed, which can vary greatly throughout a rockery. The values of friction are determined assuming smooth surfaces and ignoring the large peaks and valleys. The values of friction are fairly consistent, and generally are not dependent on the area of contact between the two rocks, but good construction practice would require that each rock should be placed so that there is a large area of contact between the rocks. . 2. OVERTURNING BETWEEN ROCKS Overturning can occur at any intersection between two rocks. The upper portion of the rockery will rotate at the outermost point of contact if overturning occurs. If the outermost point of contact is at the outer edge of the upper rock, then the rocks above have the greatest resistance to overturning. If the outermost point of contact is somewhere inside the outer edge of the upper rock, then the resistance to overturning will be decreased in direct proportion to the distance from the backside of the rock to the point of contact. When the minimum allowable thickness of rockery at a section is required to resist sliding, then the pivot point of the rockery for overturning can be behind the outer edge and still be within the required safety factor. If the required minimum thickness of rockery is to prevent overturning, then a rock should be placed that is in contact at or near the outer edge, or a thicker rock should be placed. HEMPHI LL FIGURE 47 EXAMPLE ROCKERY HORIZONTAL DISTANCE ANGLE OF TILT BACK 1, CRUSHED ROCK IS TIGHTLY PACKED TO HOLD NATURAL SOILS IN PLACE AND TO SUPPORT THE ROCKERY AND PREVENT SHIFTING, 2, FILTER FABRIC IS WRAPPED UNDER THE DRAINAGE PIPE, 3, NATURAL SOILS MUST HAVE BEARING CAPACITY TO SUPPORT ROCKERY SPIRO RESIDENCE 3. SLIDING BETWEEN ROCK and SOIL page 53 of 67 pages T~^ is probably the most predominant method of failure of a rockery, therefore the proper ;meat of the rockery is critical. PASSIVE RESISTANCE to SLIDING The soils in front of the lower rocks will provide the passive forces that will help to resist the lateral movement of the rockery. The strength of the passive resisting soils result partially from the weight of the soil in front of the rockery, and from the cohesion and: internal friction of those soils that determine their shearing strength. FRICTION RESISTANCE to SLIDING Also resisting the sliding of the rockery will be the friction forces between the bottom rock and the natural undisturbed soils, which is determined by the 'scratchiness' of the soils and the weight of the rockery. .� 4. DISINTEGRATION of the ROCKS . The disintegration of poor grade rocks is probably the second. greatest cause of rockery failures, .and because it is so obvious, is the greatest cause of litigation. The quality of rocks should be guaranteed by the quarry and the rockery contractor. W V O cc 0 W U D cc V/ Z /O ,V^^ v/ �qq ♦/b cn M co le W V LL W U O cm W V ry c~ Z CD V uJ J�q Q m O ry CL N W S>-U CJ 0' LU Y W a: 3OUFW- J C:� Z F- LL O0LU O co Q Z �W CL U. W O LL F- U Q 0 W= a_ W . d uJ ]z W 0 w J Z n n n Q CL W U z Q F- u) fn W Z O F- U LL J O N 1-1 U O. SPIRO RESIDENCE DESIGN of ROCKERY page 54 of 67 pages The rockery will be designed in 1 foot vertical increments assuming a 1 foot wide slice. Figure 48 shows the design rockery versus the way that it will probably be constructed. DESIGN PARAMETERS for ROCKERY Figure 49 gives all the presumed or tested. physical properties of the soils, and the properties of the rock, that were used by HEMPHILL to design the rockery. FIGURE 149 ROCKERY DESIGN PARAMETERS ---------------------- DESCRIPTION of PROJECT A. ROCKERY DESIGN for : SPIRO FAMILY B. PROJECT NAME . . . . : SPIRO FAMILY HOUSE C. PROJECT NUMBER . . .1636 D. LOCATION OF SECTION—: ADJACENT to DRIVEWAY E. DESIGN TRIAL NUMBER : 1 -------------------------------------------------- -- . DESCRIPTION of ROCKERY. -------------------------------------------------------------- A.'- SHAPE of SOIL BEHIND ROCKERY 1. SHAPE of SOIL ADJACENT to ROCKERY ANGLE of SLOPE VARIES from 0 to 45 degrees VERTICAL HEIGHT of SLOPE -VARIES from 0 to-10 It 2. GROUND SURFACE BEHIND ROCKERY_Is HORIZONTAL B. SURCHARGE LOADS BEHIND ROCKERY 1. POINT SURCHARGE LOADS BEHIND ROCKERY POINT NO. LOAD (LBS) DISTANCE (FT) ' 1 1,000 2 2 1,060 B' 2. NO UNIFORM SURCHARGE LOADS BEHIND ROCKERY SOIL DESIGN PARAMETERS - A. ACTIVE DRIVING SOILS s. UNIT WEIGHT . . . . . = 120 pcf b. COHESION . . . .. ... 0 Psf c. INTERNAL FRICTION 25 deg B. PASSIVE RESISTING SOILS- .. e. UNIT WEIGHT- = 110 PCf b. . COHESION . . . . . . 200 psf ; c. INTERNALFRICTION . 20.deg .ROCKERY DESIGN -PARAMETERS -------------------------------------------------------------- . VERTICAL HEIGHT of ROCKERY VARIES.FROM 0 to 10 ft' TILT of ROCKERY from VERTICAL VARIES -from 0 to 40 deg MINIMUM THICKNESS AT'TOP. . . . . . . . . . . . . _ 1.5 ft DENSITY of ROCK . . . . . . . 160 pcf % MAKIMUM ALLOWABLE. VOIDS _ ... 20"% . FRICTION FACTOR for ROCK on_ROCK •.. . . . = 0.55 FRICTION FACTOR for.ROCK on SOIL . . . _• 0.40 FRICTION FACTOR for:SOIL on ROCK . . 0.30 - DESIGN SAFETY FACTOR . . . . . . . = 2.00 SPIRO RESIDENCE page 55 of 67 pages The parameters that were used to design the rockery are explained in the following paragraphs. a LATERAL DRIVING FORCES The lateral soil forces used for design purposes were determined based on the use well compacted granular structural fill. The lateral forces on the rockery include the wheel loads from a heavy car or light truck. b. LATERAL RESISTING FORCES 1. FRICTIONAL RESISTANCE Frictional .resistance to sliding between the undisturbed soils and the bottom of the rockery will be approximately 0.4 x the vertical weight of the rockery on the soil. 2. PASSIVE RESISTANCE The existing cohesive soils directly in front of the lower rock offer passive resistance to movement at the base of the rockery. The greater the depth of the lower rock or rocks below the final grade (KEY); the greater, the passive resistance. The. minimum value of passive lateral resistance in the undisturbed soils would be determined by the strength of the soils. The properties that determine the strength of the passive soils are 200 psf cohesion and 20 degrees internal friction. SAFETY FACTOR and INSPECTION ,The safety factor applied to a rockery design is directly related to the degree of expert inspection. A lower safety factor of approximately 1.7 might be acceptable for a full time inspection, but for small walls.the inspection might be more costly than over -design. A safety factor of .2 might be acceptable for periodic inspections, where requirements for partial rebuilding of a rockery might be acceptable, or where the rockery can be slightly over -built beyond the plans to guarantee probable compliance. A safety factor of 2.5 might be acceptable for a single inspection after the wall has been completed, or where no inspection= is anticipated. HEMPHILL applied a safety factor of 2.0 for the design of this rockery, because the rockery will be small, and because minimal inspection is anticipated. p tl K• O P t0 n .p} N M N � O Y .�} 3• � M Y\ t0 O M^' Y N, N A tl 11 p p N O• � N M M J N N •O A O qtl N p S A ' q tl N Y• 0 0 0 0 N N N O O O N W 6 O a M• \ p fW[ . 0 0 0 0 0 0 �- •-N N N tl tl ♦ V p p 2♦ O N M N M P N •O P M V1 O tl F- M tl » C • p Y i N N N In N N N N N N N i.9 a p U 2 A A H ♦ Z A Ipl K O^ A n •gyp} Vpi J M N O P W n tl p 3• M • N N N A • N N M J J N N •O 0 K tl S N a Y• O O CO O N N O N O M O. 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' �.. -t yWW1 y 3 Y w A O pp[[ .m} ��p} 1r1 m Y v m ]WL .Si. 3 rl •O fV ^ M M d ti a.O T Y U A a •^ tl O♦ .•• N N N M M M M A h 1� i at hZp .t O A ^ U • O O O N N O N O 0 0 p1 '.• t] O U Z A a^• G 11 Y 2TT 0 0• O N In J •O /r N N .- .19 fY.J 7 1- x m °n p Y♦ M N M N M M M N P P P W O g p tl . ON PO1�^ .�OOpp 4 y8 y 0 Z I- p ppC[ tl 3 N M N' 4 ^ P C x 1p- U a •S- NM J.n W WIf fW[ zOi > S 6 N" Y=• N N N N N J J •O •O p! O g z VOjl 5 y "d ' p Y1yy . 0 0 0 N 1R O� O O •A Ifs O V '� r `_ W 1 tl • \ p 1[ • 0 0 0 0 O N N N N , (~yp� OC K I•' 3 UIf q O." O YI,� v V. O Z♦ O ai P O .- N •O M J M a0 L N ~ 1x• If i 0 0 0 '• '- N N M M J O K S Y J p In •- N O tl Y.'' W J W N ^' ^ .8~ cc A • O O ✓� � 2 UpY K 1 ry A • O^ l0 •O �Mp P N .tA.tpppp M Iom O . w a O W a a 3 M O P N M M N d L Y R. N •O A N O Y S m .� upY Y1,� Y8 U NWig p N \ p 1Yj1 0 0 0 O O O 1n N O O p p Y. 0 0 0 0 .•• � � � � N N OC K. J O� Z < p •^ O W OO.~-• 0 O tl Z• O m tl) P P P 1+ •O J M M S. S a 0 0 0 O O N N N M J J tl CY v y W O O 0 Y ♦ N N N N N O O O P O W W 2 0 W If Ij ^ ^ ^ ' J' J J J •O •O W X tl ♦ Cu H ♦ tJt U_ y_ F- 1<-• uSO WWU U 11 p • O N N J N J J J N � 1•- O O H Z K ej IMN�1 � A W OC O W < tl 'tl qJq OC R ` N O 11 tl 0♦ N N N N J �f 'f 1, P A t� J O u U O OOK 17 LO O .�+ . Y• 0 0 0 N N N O 0 c N^ a 0 .y-! a u 1 0 0 0 0 0 0If O aeOK < F. 3 K y n > p 2 Otl7�g71rNJP OJJ=< W w If M '? • O O O O N N N J J J J < p1 Z a • p H� O W V1Z'1 Y n w♦ \ p Ix.1 • O� � N M J N •O A q7 P O O Z F Q u S 3 gNppal y Y O N O ♦ OL p W . S. W LLO w 6 a O > N J. SPIRO RESIDENCE page 56 of 67 pages DIMENSIONS of ROCKERY Figure 50 gives the required minimum dimensions for a 1 foot section of rockery, for various rockery heights, and for various angles of tilt. All the required minimum dimensions are calculated based on the same factor of safety, therefore all the rockery options are equally safe. EXPLANATION of "ROCKERY DIMENSIONS for CONSTRUCTION" Figure 50 shows the vertical height of the rockery in the left column under HEIGHT. The required dimensions of the rockery shown to the right of HEIGHT can be for a rockery of that total height, or can be for that portion of a higher rockery. The .tilt of the rockery measured along the back of the rockery is shown at the top row in degrees, and in the second row in the ratio vertical distance to horizontal distance. The tilt back of the rockery is shown in 5 degree intervals ranging from 0 degrees (verticao to 40 degrees. At each interval of height the required thickness of the rockery to resist sliding and overturning at that interval over the next rock down is shown under the column .THCK for THICKNESS' of rockery. As shown in Figure 47 on page 53, titled 'EXAMPLE ROCKERY", the thickness is. measured from the front of the rockery to the rear. The dimension given under the OWN column: is the minimum allowable distance measured from the front of the rockery to the pivot point of the rock to prevent overturning. The pivot point is the first point of contact between two rocks measured from the front of the rockery. If the OWN parameter is 0, then the 2 rocks at that height must be. in contact at the very front edge of the rockery, and the required rockery thickness was determined for overturning rather than sliding. If OWN is greater than 0, then the required minimum rockery thickness was determined based on sliding, and the pivot point can be less than the required thickness for sliding. If the value for OWN is greater than the thickness of the rockery, then the rocks are apparently leaning into the slope, and overturning is negative and is not a problem. The values shown under the column KEY, indicating the depth to key the bottom rock, is the required depth of the bottom rock or rocks to be placed below the ground surface to achieve resistance to sliding. The required key shown at each height is only for a rockery with that total height, otherwise the value has no meaning if the rockery has a greater height. The horizontal distance taken up by the'rockery from the front of the bottom rock to the back of the top rock is shown under the column HD for 'horizontal distance'. That value will help to choose the rockery that will best fit into limited spaces. The total weight of the rockery for that particular height and angle of tilt back is shown under the column WR for 'weight rock'. That value can be used to help choose the cheapest rockery, and can also be used to estimate the cost of the rockery at that location. . . HEMPHILL SPIRO RESIDENCE page 57 of 67 pages QUALITY AND SHAPE OF ROCKS To prevent deterioration from weathering, only top quality rocks should be used. The rocks should be hard, sound, durable, and should be free from seams, cracks, and other defects tending to destroy resistance to weathering. NO GOOD! The rocks should have a density of approximately 165 pcf since that was the density used for the rockery design. If rocks of a different density are used, then the required dimensions shown on pGk•ROCKERY DIMENSIONS for CONSTRUCTION, must be adjusted in direct proportion to the change in density. The rockery should be redesigned to prevent any confusion. <' PLACEMENT of ROCKS NO GOOD!, Rocks should have fairly flat tops and bottoms to allow for adequate contact to resist overturning, and to allow for a relatively tight wall. Rocks should be placed so that the vertical seam between 2 adjacent rocks is not above or below the vertical seam for the upper and lower layers. In other words, as much as possible, each rock should overlap at least two different rocks below. Rock shapes should be chosen and placed so that no more than 20% of the wall face is voids. A GOOD! higher percentage of solid rock increases the required weight of rock needed to resist overturning and .sliding. If a different void volume is placed, then the required rockery sizes must increase. in direct proportion with the increase in voids so that the required rockery weights to resist sliding will be achieved. ------' WORKMANSHIP for ROCKERY CONSTRUCTION Because of the angular and inconsistent shape of rocks that are available in the Seattle area, it is difficult to control the dimensions of a rockery. It is also difficult for workers to understand the complexities of a rockery, and the meaning of any deviations from the plans,.since any plans for a rockery are extremely idealized. Therefore, even the most conscientious of workers could place rocks in a dangerous manner that would only be obvious to an expert. FILTER SYSTEM A properly constructed filter system behind the retaining wall is imperative to prevent the .loss of structural fill behind the rockery resulting from seepage erosion from infiltrated rainfall or runoff. HEMPHILL f �z---------r t--------r��----- -r-.L- SPIRO RESIDENCE page 58 of 67 pages As shown in 'EXAMPLE ROCKERY` on. page 63, the first layer of the filter system behind the rockery should be composed of crushed rock that is tightly packed between the rocks and the natural soil to give the soil lateral stability. The crushed rock should be backed by either a filter soil or a filter fabric to prevent the infiltration of the soil into the voids of the crushed rock, depending on the gradation of the natural soils, and on the availability of suitable filter soils, and the ease of placement. Any other filter methods can bethe option of the contractor, with the approval of HEMPHILL ROCKERY DRAINAGE The need for rockery drains, their locations, and their design, should be determined by HEMPHILL after -the true groundwater conditions have been exposed at the time of construction. The required height of the drainage system will be dependent on the potential height of the seepage zone, which should be determined by HEMPHILL at the time of construction.. All rockery drains must have a filter system to! prevent the, natural soils from. being eroded into the drainage system, and to prevent the creation of voids adjacent to the drainage system. The preferred filter system is a filter fabric. If a soil filter is desired, then the backfill materials placed behind.the rockery must be controlled to prevent the infiltration of the natural soils, but to not erode through the void spaces in the rockery. Generally, the cost of testing to determine the existing soil sizes, and the engineering to determine the proper backfill material, and the difficulty of obtaining the designed materials, and the difficulty of placing multiple filters; is not justified. Generally, perforated drain pipes should be located in a manner to lower water below the bottom of the rockery, and to prevent the potential undercutting of the rockery by erosion. The location of rockery drains will sometimes be dependent on the method. of construction of the rockery, and the location of adjacent excavations. Rockery drains should be sloped to allow drainage without creating low spots where water will accumulate. HEMPHILL recommends a slope of at least 12/1 U. The size and type of perforated pipe should be determined by HEMPHILL based on the anticipated vertical loading, the quantity of water to be conducted, and the grain size of the adjacent drainage material. The perforated pipe should be connected to solid pipe after leaving the area to be drained. The solid pipe should not be connected to any other drainage systems before a catch basin that can overflow below the lowest elevation of the rockery drain. That will prevent another drainage system, such as a downspout, from clogging and backing up through the rockery drains. FIGURE 51 LOCATION of NEW INTERCEPTOR DRAIN—— r1k Y, 10 Me 'sus, oo:l .0. o 00 14e ,O,oiv 40 oor .7— All 'A "Mi V.FL v," ;1Z 2e SPIRO RESIDENCE page 59 of 67 pages The required drainage backfill will depend on the quantity of water to be intercepted, the required height of drawdown compared to the horizontal distance of the backfill trench, the grain sizes of the adjacent natural soils, and the type of filter system that is used. The figure 'EXAMPLE ROCKERY'. shows a rockery drainage system. DRAINAGE EXISTING INTERCEPTOR DRAIN There presently. exists on the site an interceptor drainage system that is located at the toe of the bench; that then conducts the intercepted water to a drainage system located alongside Meadowdale Road. NEW SUBSURFACE DRAINAGE The interceptor drain at the toe of the bench will be removed and relocated to the top of the excavated bench behind the proposed soldier pile wall. The new drain will be located as shown in Figure 51. Figure 52 on the. next page shows the proposed interceptor drain system behind the soldier pile wall. The location of the drain is based on the assumption that the excavation for the new bench will be into the hard clay, and that any groundwater seepage will have been encountered behind the soldier pile wall. If the groundwater seepage zone has not been encountered as anticipated, then excavations should continue to the top of the hard clay. If necessary an interceptor trench can be conducted separately from the soldier pile drainage system. SITE SURFACE DRAINAGE To prevent erosion of downhill slopes, HEMPHILL recommends that stormwater runoff from adjacent sites, and stormwater from impervious areas on the site, includingrunoff from roof drains, should be intercepted and conducted to a stormwater drainage system approved by the building department authorities. Water from the parking area and driveway should be conducted to a catch basin designed to entrap oil and silt.. Figure 53 on the next page shows the location of the proposed stormwater detention system that will collect surface water runoff and control the rate at which it enters the municipal system. The ground surface should be sloped away from the structure to prevent the accumulation of water adjacent to the grade beams that could then seep into the crawl space. H E M P H I LL FIGURE 52 SOLDIER PILE DRAINAGE 4„ STEEL BEAM `.COMPACTED SOIL t_ LAGGING f , t kFILTER `.FABRIC 12„ — PERFORATED PIPE �0 o�:O O QQ Q O •.t d (. �. O OOP •o. t# CONCRETE PILE. oe000�Q .e ° °po0 go�o�'p Qo°o°oa a cop aoo0 • ;Q " s :C 0�000�0 - ' p°.00�90�Q0 o oOQo .QoQ,p .. o 'op.o A O �p oQ.O o O o Q0c3:'0 n� � oa �° Q f ;D pep oo•,o. �oo'p'QQ 0 o'D ti A. DRAINAGE BETWEEN PILES 1, EXCAVATE BETWEEN PILES A 4" SPACE BEHIND LAGGING FOR DRAINAGE. 2. PLACE FILTER FABFIC AGAINST EXCAVATED SOIL AND ON TOP OF CONCRETE PILE. 3. PLACE PERFORATED PIPE DIRECTLY ON FABRIC OVER CONCRETE PILE° 4. FILL SPACE WITH GRAVEL APPROVED BY HEMPHILL TO -WITHIN 1� FROM FINAL GRADE. WRAP FILTER FABRIC OVER TOP OF GRAVEL. S. FILL LAST 1' WITH SOIL AND COMPACT. B, DRAINAGE BEHIND PILES 1. EXCAVATE THIN SPACE BEHIND BEAM, WITH LARGER SPACE AT BOTTOM FOR PERFORATED PIPE, (IF HOLE STAYS OPEN, SPACE IS LARGER THAN SHOWN, AND CAN BE BACKFILLED WITH GRAVEL ON BEAM SIDE, OR SOIL ON OPPOSITE SITE OF FABRIC. 2. PLACE FABRIC BY SLIDING DOWN FROM TOP, OR THROUGH FROM SIDE. 3. PLACE PERFORATED PIPE BY SLIDING FROM SIDE, OR DOWN FROM TOP IF HOLE HAS STAYED OPEN. C. ALTERNATIVES THERE ARE MANY ALTERNATIVES AT THE OPTION OF THE CONTRACTOR WITH THE APPROVAL OF HEMPHILL. SPIRO RESIDENCE page 60 of 67 pages FIGURE 53 PROPOSED STORMWATER DETENTION ELI /.or✓� . ' 1 J.sv I. � � I 1 kh 1 O� hl �� 1 Alf rr ci ol ol �^�._.--.- if --'�Zo I .01 Mi�•�� � � \ Oh ♦\T 1 - •\` I A � — `\ �/ ter. /.ve _ - `•\ lldya f F� / re•� r RIO • _ r R t{ Fay. f t,,€ �b HEMPHILL SPIRO RESIDENCE page 61 of 67 pages DRAINAGE of GARAGE SLAB BASE COURSE The garage slab base course or capillary break should be open to drainage to prevent the accumulation of trapped water within the garage grade beams. As previously explained, the excavation under the garage should be sloped to the northwest at least 1'/10' to prevent any water from becoming trapped under the garage slab. To allow for the escape of any trapped water, the drainage can be openings in the grade beam along the east side of the garage, or gravel filled trenches can be installed beneath the garage floor slab, that are then connected to an outside drain. The type and number of drains can be determined at the time of construction. The garage slab base course drain can be, incorporated with the crawl space drain by allowing any seepage to flow thru the grade beam between piles 4, 5, and 6 and into the crawl space. HEMP H.I L L SPIRO RESIDENCE page 62 of 67 pages CRAWL SPACE DRAINAGE Standing water in a crawl space is generally not desirable, but it is not necessarily detrimental, unless contact with wood structural members causes rot, or high humidity seeps into the living areas. The most serious result of wet crawl spaces ,can, be•decay -of the wood .structural members. Literature describing the cause and prevention of wood'decay is published'in the.U.S.D.A. Forest Service Research Paper FPL 190, and also in the U.S. Department of Agriculture Home and Garden Bulletin No. 73. Local building codes include specifications similar to the recommendations presented by these publications for the prevention of decay. Wood decay is caused by fungi that can occur in several forms. The U.S. Department of Agriculture describes those fungi as brown rot, white rot, and several other less common forms. For decay to occur, spores of the fungus must be present, and to survive and propagate the spores. need wood, water, oxygen, and an acceptable temperature, preferably between 50 and 90 degrees. Generally, most crawl spaces have all of the ingredients necessary to propagate the fungus. The literature published by the U.S. Department of Agriculture describes the prevention of decay as simply denying direct contact between water and the wood structural members. The direct contact can occur in 3 ways: 1. Wood structural members can be placed adjacent to damp soils, which. is against all acceptable construction practices. 2. Water can rise in the crawl space to contact the wood structural members. 3. Warm, humid air can condense on colder surfaces adjacent to outside cold air, or adjacent to upper air conditioned floor systems. Short time wetting of...wood structural members.during temporary infrequent flooding conditions would not be damaging if the wood members could dry quickly and completely. If flooding occurs frequently, or if the wood members cannot dry quickly or completely, then the rising of water in crawl spaces can be controlled by gravity drainage placed below the level of the lowest wooden structural member. High humidity can be controlled by covering.the damp soils with plastic, or the humidity can.be removed by placing properly: sized and located air vents to allow air circulation within the crawl space. Local building codes generally, include specifications that require both plastic covering and property designed air circulation. HEM PH I LL SPIRO RESIDENCE page 63 of 67 pages HEMPHILL recommends that the crawl space be covered with plastic, and that the proper ventilation be installed with care not to allow dead air spaces. THE PLASTIC COVERING SHOULD END AT THE FOUNDATON WALL AND SHOULD NOT BE PLACED UP THE FOUNDATION WALLS AND NOT IN CONTACT WITH THE SILL PLATES. HEMPHILL- recommends that any water that seeps into the crawl space should be able to escape through a gravity drain that is placed within the crawl space adjacent to the lowest outside area that can accept the gravity drainage. The crawl space should have been excavated to slope down at least 6 inches, or 1' per 101, to the low side of the crawl space, as previously explained. A gravity drain can be a solid pipe that is placed under or through the grade beam, and that will conduct water to the recommended outlet. The crawl space drain, any footing drains, and the garage slab drain can all be combined and run into the interceptor drainage system, or they can be open to a lower ground surface, but they must not be connected with the. surface runoff system. unless there is an open catch basin at the connection that is below the level of the crawl space or any grade beam drains. If the outlet pipe is open to disperse the water onto the ground surface, then the pipe should be perforated for the length that is exposed at the. end to allow any water to disperse, and should be capped to prevent the entrance of. creatures into the crawl space. DRAINAGE for GRADE BEAMS The need for grade beam drainage systems, their locations, and their design, should be determined by HEMPHILL after the true groundwater conditions have been exposed at the time of construction. Since the grade beams will be formed on the crawl space surface, then any drainage system placed at that level would probably be useless, and any water would seep under the grade beams and into the crawl space. If the quantity of potential seepage water is low, then grade beam drains will not be required. If it is determined that water should be intercepted outside the crawl space, then drains should be placed in a trench outside the crawl space at least 6 inches lower than the grade beams, and sloped to flow, as previously recommended. Any grade beam drains can be combined with the crawl space drains and connected with the interceptor drainage system. DRAINAGE for. RETAINING WALLS The retaining walls at the northeast .corner :of the house will require 'footing drains' to prevent hydrostatic pressures, and to prevent seepage through the walls. The required height of the foundation wall drainage system will be dependent on the potential height of the seepage zone, which should be determined by HEMPHILL at the time of construction based on the structural fill used, and the potential for water intrusion into the soils. 0 z_ Z J Q _! O0 y- z oz W w cr. 2 CM Kr Ln LU LL iD a WW QLLJ O W m p Lu Oz 0= ao U)a. U 0m U)� °�cc CL ''':• llllll!!!!l!!I!!!I!! ui � Q i�7ity.y+`;�'�w;l�t�;:,�.��:t'�j'ij';�;:,�;)�;:.�,�' ���;�V1�'�Y�{3`• '%�;+�':�:T,: ��S 7•ir�/.� �f��� ''ti•f! j•`•\r,} (,�1 ,.��lrl.. r.� �� �,l�j �. y 'i�1�'1 �h '+�:•.. ; . . KK��,y�I ,. i �! l��' , i;Cy` I}�}: .I,ita��y.\,t;��,r,,,.�t��r,• ,�r.-Il�+"\'r.'.•o T r > m ( it �.;,; , •�; Z i�.6 ' '• •', w W J J U LL (5 WL�u Oa �wCc .4 C -i- a Z��� j-O a�a w wN W'a(n =a~° a: pJ. aJZ p2WZ ww> >> g=-Z a�"O a0OC o O= zwzU a?m0 NN a=O� CL<< QCC- u- wp (n>. Um pm t-- O aQ =Ww0 H cc <p 2m3r.0 WF.•U-- t-OOw. sDN z waojE i J= rr pm>> a ° W O LLOmmLiJ O-jo a Q0 M5 mCCp a <0aLIa (L<o W =c.N p -10Ma W oCC= W wg� a_.- -J==X <Wn -'w OF-Ow2w Z " , 1't����>j�li�iq l��(}'frr�'r�{yyt',,'��t t' ''�•'• .� f.}tCi�y7l��lfltir;l `rii'I{l�?!1!fY••'��;,' :�.•'1 .. fit, ••r{} ,,,.>+}t,, �' ,.:„••,•; 1 iy,•IXri}r'{i4\;{Rsr�,r' , (�r�i�ii?::t'.�1 1•�� �r,7,1f1 r; ��:j114'; C�;j''tt {f i +��i.}j:, •l+ �•, •. , , , {�,+1r,.y4,,, dG t4•jryY i1,'\,��r��rY/��rt'�+1 s r}rr:l'I�S`i,••i'Ui., ,( (rq,,�:,1• , ti�l ;il'q�,y>< •t h(t•�}: av;i ti� t''rir • p ;:.:.:.;. �•••li:+rv'rrirllaSi:1( ���}r}`" kPd:: f7r:ol.:},\t,;•U{t)?�.Ia,irf Q 4rr ' JLn o O w�U g1-& W G. maw 0 zM° .. O UjL)M U C `{,��t'.�,tr```1•iii,��}4'{• .1.> �: � rJ�j`1'�`,+j{j..�,ij'j{i.!`{t. l�: ! /,•} l i I I I I5,ir {�r�{�rri 1� ,4}t •h i.�'rr l�'"! jj{{ ,:r .�:S'ra itt' %) cc I � I I (I •ftr r's•4 v.y} �,��;• ���i•� , ���, 1t : i��5 f� �r,1 '' 11{13333 �'t� � • h 11 I I11<yi';�y�•�f+'ir'jY{r.4,,f;!r:.;�. � ,. •�. �Il,lilil � a -4 .'p • ' �• 4' t Z_ U pW 0 ll� w N r� Z C'3 W SPIRO RESIDENCE page 64 of 67 pages The retaining wall drainage system must have a fitter system to prevent the natural soils from being eroded into the drainage system, and to prevent the creation of voids adjacent to the drainage system. The preferred fitter system is a fitter fabric. Generally, the main purpose of the retaining wall drainage system will be to lower the groundwater adjacent to the wall to reduce the potential hydrostatic pressures against the wall. The drains might also be required to prevent groundwater from seeping through the wall. to the interior Irving area, or under the wall to the crawl space area The retaining wall drainage system should be sloped to allow drainage without creating low spots where water will accumulate. The size and type of perforated pipe should be determined by HEMPHILL based on the anticipated vertical loading, the quantity of water to be conducted, and the grain size of the adjacent drainage material. The perforated pipe should be connected to solid pipe after leaving the area to be drained, and the trench carrying the perforated and the solid pipe should not step up, otherwise any water running under the pipes will be trapped. The solid pipe should not be connected to any other drainage systems before a catch basin that can overflow below the lowest elevation of the perforated pipe. That will prevent another drainage system, such as a roof drain, from clogging and backing up through the retaining wall drains. DOWNSPOUTS OR RUNOFF DRAINS SHOULD NEVER BE CONNECTED TO RETAINING WALL DRAINS. The required drainage backfill will depend on the quantity of water to be intercepted, the required height of drawdown compared to the horizontal distance of the backfill trench, the grain sizes of the adjacent natural soils, and the type of fitter system that is used. Figure 54 shows 3 optional methods to intercept groundwater and conduct it away from the retaining foundation wall. The options should include that the drains should be located below the level of the interior crawl space. PAVING DESIGN of SUBBASE COURSE to RESIST CAPILLARY WATER Because of the potential high groundwater table at the site, and the silty nature of the soils above the groundwater, capillary water might exist within the soils directly beneath the base course for the driveway. To prevent the accumulation of capillary water within the frost zone of the base course, HEMPHILL recommends that. the combination of paved surface and base course be 1 Z thick, and that the base course be composed of granular soils with a minimum size 1/4, aggregates. HEM PH I LL SPIRO RESIDENCE page 65 of 67 pages The granular.base course should be open to drainage to prevent the entrapment of water. The granular base course will prevent the accumulation of capillary water which could freeze within 12 inches of the ground or roadway surface. The freezing process will create ice lenses which allow more capillary water to rise, because the frozen capillary water no longer acts as weight resisting the rise of the capillary water. The growing ice lenses will heave the paving. The heaving can be most damaging adjacent to the garage doors and the back porch. After the ice lenses thaw, the remaining pocket of water will soften the adjacent soils, and will also deflect under the pavement when wheel loads are applied, causing the paving to fail. If the base course is composed of aggregate with large void spaces, and is placed directly on the fine grained natural soils or structural fill, then a filter should be placed between the soils to prevent integration of the fine soils into the granular void spaces. The large aggregate would punch into the fine grained soils and settlement would occur. A filter can be a fabric, or it can be composed of soils designed by HEMPHILL.in accordance. with the adjacent aggregate sizes. The various aggregate sizes and filters can be determined by the contractor in accordance with the best and cheapest available materials, and with the approval of HEMPHILL HEM PHI LL SPIRO RESIDENCE page 66 of 67 pages FUTURE STUDIES and RECOMMENDATIONS DESIGN REVIEW HEMPHILL has reviewed the final plans and specifications and determined that they are reasonably in accordance with the recommendations presented in the geotechnical report; tassuming that HEMPHILL will conduct the recommended geotechnical inspections, and will present any necessary adjustments resulting from differences between presumed site conditions and actual site conditions, along with some options by the contractor, in accordance with actual conditions encountered at the time of construction. CONSTRUCTION INSPECTIONS and VERIFICATIONS 1. HEMPHILL should inspect the soils that are exposed in the borings for piles to verify that the required resisting soils and the allowable bearing soils have been encountered, and that there are no unexpected conditions that would require changes in pile design. 2. HEMPHILL should verify that the steel and concrete are properly placed in the borings to achieve the desired design conditions. 3. HEMPHILL should inspect, and if necessary conduct tests, to determine that any structural fill is composed of the proper soils, and that the required density has been achieved by the.compaction process. 4. HEMPHILL should inspect the excavations to verify any suspected groundwaterconditions, or to determine any unexpected groundwater conditions, or to determine any design changes. 5. HEMPHILL should determine that any perforated drain pipes are placed at the proper locations to achieve the required drainage, and that the intercepted groundwater is properly conducted from the site. 6. HEMPHILL should inspect all surface runoff drainage systems to determine that surface water is properly intercepted and conducted from the site, and that the runoff systems are not improperly tied to the subsurface system to cause the runoff system to back up into the subsurface system. 7. HEMPHILL should determine that any drainage backfill has the required permeability, and,that'`.- properly designed and installed fitters will protect the drainage system from clogging by fine grained soils that could be eroded into the drainage system by groundwater seepage. SPIRO RESIDENCE page 67 of 67 pages B. HEMPHILL should determine that the garage floor slab, and the driveway paving, are underlain by a proper base course to protect against damage from freezing. 9. HEMPHILL should determine that the crawl space is property drained and prepared to prevent high humidity and entrapment of water. 10. HEMPHILL should verify that any rockeries are properly constructed and drained. Dale C. Hemphill P. E. . (0c L P rj'. 00/ Registered Engineer No. 14777 State of Washington '�14m �� . `ru t h-_- . l'rJ , is 1 C:•J — h i i� �i�iu.u.i�i� N�',�C �' mil,, •� •• ����r � to , u,�•y . � r � i�C, • I� in in RE m I ■E,n�LisG' IRE iElC EEnlES.T�� � i�! �.��`.. f�r�. ,�1 1•% v Imo; -•�;_ �, ,..'��', � ■FYI Q� H E P H I L L® CONSULTING ENGINEERS 9 9 9 W Q N a 0 �u� m a t > (nn Z w - > Q W Z 0 J W w (n O 0 zzz J Q Q N 0 9 9 9 w 0 N N w_ N 0 O W N F a a � o > Z a W �z w Q '- 0 0 (n i 9 9 Z u E ;-- C W U F W W U Z 0. 0 (n Z Z Z 0 w Z H O w >Y H H > Q F N w a 0 a w 3 a o e N 0 _Z 0 w Q Q LL w Q 0 Z O m J Z X Q W W Z U Z 0 N 0 tNj 0 ? 0 a (n (n 9 e 9 GEOTECHNICAL ENGINEERING FOR THE PROPOSED SPIRO RESIDENCE TO BE LOCATED AT 15631 75th PLACE WEST EDMONDS, WASHINGTON 10 DECEMBER, 1990 921 109T" AVENUE S. E. ® BELLF\/I IF \n/o TABLE of CONTENTS INTRODUCTION page AUTHORIZATION for GEOTECHNICAL ENGINEERING . . . . . 1 PURPOSE of GEOTECHNICAL ENGINEERING . . . . . . . 1 PURPOSE of GEOTECHNICAL INVESTIGATION . . . . 1 PURPOSE of GEOTECHNICAL REPORT . . . . . . . . 1 DESCRIPTION of PROJECT . . . . . . . . . . . . . 3 RATIONALE for INVESTIGATION and RECOMMENDATIONS . . . 4 ASSUMPTIONS for GEOTECHNICAL ENGINEERING . . . . . 5 LIMITATIONS of INVESTIGATION and REPORT . . . . . . . 5 Gf.01-ECHNICAL INFORMATION for the CONTRACTOR. 6 SITE INVESTIGATION SURFAC12 DESCRIPTION . . . . . . . . . . . . . . 8 SUBSURFACE INVESTIGATION . . . . . . . . . . . .. 8 RATIONALE for INVESTIGATION . . . . . . . ... . 8 METHODS of INVESTIGATION . . . . . . . . . . . 9 HISTORY of SITE . . . . . . . . . . . . . . 9 GEOLOGICAL RESEARCH . . . . . . . . . . . . 9 VISUAL OBSERVATIONS . . . ... . . . . . . . 10 FIELD TESTS . . . . . . . . . . . . . . . . 11 GROUNDWATER OBSERVATIONS . . . . . . . . . 15 SITE STABILITY INVESTIGATION . . . . . . . . . . 17 SOIL DESCRIPTIONS . . . . . . . . . . . . . 17 HOW PHYSICAL PROPERTiE13 of SOILS DETERMINED . . . 17 DESCRIPTION of UNDISTURBED NATURAL SOILS. . . . . 18 CONCLUSIONS . . . . . . . . . . . . . . . . . 21 ENGINEERING STUDIES and RECOMMENDATIONS RATIONALE for RECOMMENDATIONS . . . . . . . . . SEISMIC STUDIES . . . . . . . . . . . . . . STABILITY STUDIES . . . . . . . . . . . . . . SITE PREPARATION . . . ... . . . . . . . . CLEARING .and STRIPPING . . . . . . . . . . PROOF ROI NG . . . . . . . . . . . . . . PURPOSE of PROOF ROLLING . . . . . . . . DESCRIPTION of PROOF ROLLING . . . . . . . PLACEMENT of WORKING SURFACE . . . . . . . GENERAL SITE EXCAVATING DESCRIPTION of EXCAVATING . . . . . . . ALLOWABLE SLOPES for SIDES of EXCAVATIONS GENERAL SITE FILLING . . . . . . . . . . . . DESCRIPTION of FILLING . . . . . . . . . . DESCRIPTION of STRUCTURAL FILL . . . . . . PREPARATION of EXISTING GROUND SURFACE 23 23 26 28 28 2.9 29 29 29 29 30 30 31 31 31 32 "PiVi"I I I page PLACEMENT of STRUCTURAL FILL on SOFT SOILS . . . 32 CONTROL of COMPACTION of STRUCTURAL FILL 32 DENSITY REQUIREMENTS of STRUCTURAL FILL 35 COMPACTION of BACKFILL ADJACENT to STRUCTURES 35 DESIGN PARAMETERS for TEMPORARY FOUNDATIONS . . . . 36 PREPARATION of EXISTING SOILS . . . . . . . . . 36 APPROVED BEARING SOILS . . . . . . . . . . . 36 BEARING CAPACITY of APPROVED SOILS . . . . . . . 36 SETTLEMENT ESTIMATIONS . . . I. . . . . . . . 37 SETTLEMENT of GRADE BEAMS . . . ... . . . 37 SETTLEMENT of GARAGE SLAB . . . . . . . . . 37 SETTLEMENT of BACK PORCH . . . . . . . . . 38 SETTLEMENT of DECK & STAIRS . . . . . . . . 38 DESIGN and PLACEMENT of SPREAD FOOTINGS . . . . . . 39 DESIGN of SPREAD FOOTINGS . . . . . . . . . . 39 OVER -EXCAVATIONS to BEARING SOILS . . . . . . . 39 MINIMUM WIDTH of FOOTINGS . . . . . . . . . . . 40 MINIMUM DEPTH of FOOTINGS . . . . .. . . . . . 40 MINIMUM DEPTH for BEARING . . . . . . . . . 40 MINIMUM DEPTH for FROST PROTECTION . . . . . . 40 DESIGN of GRADE BEAMS . . . . . . . . . . . . 40 DESIGN of PILE FOUNDATIONS . . . . . . . . . . . . 40 DESCRIPTION of PILES . . . . . . . . . . . . . 40 MINIMUM DEPTH of PILES . . . . 42 MINIMUM DEPTH of PILES for BEARING . . . . . . 42 MINIMUM DEPTH for STABILITY on SLOPES . . . . . 42 END BEARING for PILES . . . . . . . . . . . . 42 SIDE FRICTION for PILES . . . ... . . . . . 42 DESIGN of INDIVIDUAL PILES . . . . . . . . . . . . 44 DESIGN of RETAINING WALL PILES . . . . . . . . . . 46. DESIGN of SOLDIER PILE WALL . . . . . . . . . . . . 49 CONCRETE FLOOR SLABS . . . . . . . . . . . . . 51 DESCRIPTION of CAPILLARY WATER. 51 PREPARATION of BASE COURSE for FLOOR SLAB 51 PROTECTION of FLOOR SLAB from CAPILLARY WATER . . . 51 DRAINAGE of SLAB BASE COURSE . . . . . . . . . 51 ROCKERY . . . . . . . . . . . . . . . . 52 DRAINAGE . . . . . . . . . . . . . . . . . . 59 EXISTING INTERCEPTOR DRAIN . . . . . . . . . 59 NEW SUBSURFACE DRAINAGE . . . . . . . . . . 59 SITE SURFACE DRAINAGE . . . . ... . . . . . . 59 SLAB DRAINAGE . . . . . . . . . . . . . . . 61 CRAWL SPACE DRAINAGE . . . . . . . . . . . 62 GRADE BEAM DRAINAGE . . . . . . . . . . 63 RETAINING WALL DRAINAGE . . . . . . . . . . . 63 PAVING . . . . . . . . . . . . . . . . . . 164 FUTURE STUDIES and RECOMMENDATIONS DESIGN REVIEW . . . ... . ... . . . . . . . . . 66 CONSTRUCTION INSPECTIONS and VERIFICATIONS . . . . . 66 LIST of FIGURES =1GURE TITLE or DESCRIPTION PAGE FIGURE TITLE or DESCRIPTION PAGE 1 LOCATION of PROJECT . . . . . . . . . 1 28 EXCAVATED SOILS . . . . . . . . . . . 30 2 VIEW of PROPOSED HOUSE . . . . . . . 2 29 OVER -EXCAVATIONS . . . . . . . . . . 36 3 PLAN of PROJECT . . . . . . . . . . . 3 30 SETTLEMENT VS LOADS, ETC. . . . . . . 38 4 SECTION of PROJECT. . . . . . . . . . 4 31 LOCATIONS of DECK FOOTINGS 39 5 VIEWS of HOUSE . . . . . . . . . . . 5 32 LOCATIONS of PILES . . . . . . . . . . 40 6 VIEWS of HOUSE . . . . . . . . . . . 6 33 DESCRIPTION of RESISTING SOILS . . . . 42 7 TOPOGRAPHIC PLAN of SITE . . . . . . . 8 34 LATERAL FORCES on INDIVIDUAL PILES . . 43 8 GEOLOGIC MAP of VICINITY . . . . . . . 9 35 SECTION of INDIVIDUAL PILES . . . . . . 44 9 LOCATIONS of FIELD TESTS . . . . . . . 11 36 DESIGN PARAMETERS for INDIVIDUAL PILES 45 10 LOGS of TEST PITS . . . . . . . . . . . 11 37 DESIGN of INDIVIDUAL PILES . . . . . . . 45 11 DRILLING EQUIPMENT . . . . . .. . . . 12 38 RETAINING WALL PILE DESIGN PARAMETERS 46 12 LOG of BORING 1 . . . . . . . . . . . 13 39 DESIGN of RETAINING WALL PILES . . . . 47 13 LOG of BORING 2 . . . . . . . . . . . 13 40 SLIDE FORCES on RETAINING WALL PILES 48 14 EQUIPMENT for SPT . . . . . . . . . . 14 41 SECTION of SOLDIER PILE WALL . . . . 49 15 SPLIT SPOON SAMPLER . . . . . . . . 14 42 CONSTRUCTION of SOLDIER PILE WALL 49 16 INTERCEPTOR DRAINAGE . . . . . . . . . 15 43 SOLDIER PILE DESIGN PARAMETERS 50 17 CAPILLARITY . . . . . . . . . . . . . 16 44 DESIGN of SOLDIER PILE WALL . . . . . . 50 18 SECTION of SLOPE to RAILROAD . . . . . 17 45 CAPILLARY BREAK . . . . . . . . 51 19 ESTIMATED GEOLOGIC SECTION 21 46 LOCATION of ROCKERY . . . . . . . . . 52 20 MAP of SEISMIC ZONES . . . . . . . . . 23 47 EXAMPLE ROCKERY . . . . . . . . 53 21 DESCRIPTIONS of SEISMIC INTENSITIES 24 48 DESIGN VS CONSTRUCTED ROCKERY 54 22 LIQUEFACTION . . . . . . . . . . . . 25 49 ROCKERY DESIGN PARAMETERS . . . . . 54 23 SECTION for STABILITY STUDIES . . . . . 26 50 ROCKERY DIMENSIONS for CONSTRUCTION 56 24 EXAMPLE STABILITY CALCS . . . . . . . 27 51 LOCATION of NEW INTERCEPTOR DRAIN . 59 25 STABILITY CALCULATIONS PARAMETERS. 27 52 SOLDIER PILE DRAINAGE . . . . . . . . 60 26 STABILITY CALCS . . . . . . . . . . . 28 53 PROPOSED STORMWATER DETENTION 60 27 WORKING SURFACE . . . . . . . . . . 29 54 DRAINAGE OPTIONS . . . . . . . . . . 64 . HF 1 !0 1 r—" H I I L_ FIGURE 1 LOCATION of PROJECT 1 ~rrRQ �. PL S 148TH 149TH N U H M A SO UND �� FISHERI aIR �,1 `�° ��a ; N 149T PL SW P SW ST W 1�TH PL Q� $W 150 H PL SW —r75QTH -PL S'. 151 STCl 51 ST STtSW I i 150TH4.pv*,p ON 3 3 � aPL SW v� of 152ND ST SW a �' �a 152NO3 S- �l ( 3:153RDST� a 'a is •• ::: Q 1Ln 53D PL SW a ►- L0 153Q Pl 15 13 QI .�... > N > PLSW �- !a156TH T. ` ISW —__ i 56TH Q ST > SW 7TH �; MEAD0WDALE '� 3 157TH ST EA D >I BEACH,.:.:::.: 5' u -i 157TH PL SW SW I 158TH ST WI ` ::'. QI•.PARK."' =1157Tfi PL SW 158TH PL SW. ' D o;1 T PL SW�•... i 0i q- 4. n. M p p "I' ' J i lr z a. 3 _ _t"I J 5AEWHARFN 3 I� fi= 160T =---1�s -mow_ — � W m s � - — 3 Fl , iC 1160TH PL SW arc Q a I ' D�ls1s)e�L sw ( I I a "� CL 161 ST PL SV`i n�a AV W NI •��� I 162ND �IPL SW i I H ♦_` I / Y63RD ST WSW � 163RD PL SVY 164TH la S A� p163RD SW Q I 3164TH I ST SW �s s' > = > 164 H I PLLO I Q 165TH Q PL sj ,wOOD PLS Q �3J��a : :I�.:.: ' 1 16dT > BEVERLY ` ag O�IS 'cc167TH a168TH ST LO v y168TH ST ::.; SW P SN >� 168TH _- •_-emu, MEADQ�A13Q� MEAD01(VDALE_ PL SW 169 H PQ vP0 _ I� -P -- I �I a Z iMID- > F 69TH 1 b'9TA PL-�W — — — — I- jC17� 00l_ _ J �< �7 �104 � � � 1 170 H PL Sb1, ST tw 170TH tQ SW 170TH PL SW I 3I� S a `NN SW ^ I O `�I I > ~ 3 OP 171ST �> 1 17SW PL J ��P = 172ND ST 172NO Q cL �"I — _ Q_L a172ND __ SW OQ' > E SW Fy ST ISW Q� OP ST SW Q1�SW = 72ND PL SW 9 '3RQ�a ¢Pa SW, �',y �i2y .� o� : 172NO ST' 172ND ST SW > 9 �' o sT 9Q '39��° 173RDSW 1173RD � 173RD PL W 14T SW _a n 174TH STI Sw SW �`'2Q a SW I-- a175TH 0 UwFknT 17WHST ( P s� 1 tri I LO LO x ST n• z �„J 1 � cD rP� s7� ST � < ° � � I SW � L 1 :SOUND••VIF 1swH I� a a z 1nr ST 176tH PL SW 3 �� +' Z > 2 �S . SW L '',•• — OR 177TH T SIN = 177TH n 178TH I ST SV/♦ul 178TH a;179TH Q a c"'c a P SN NonarsH --I 178T11 PL - SWE- 1781H 1 T SIN , _ > 1 COUNTY ] I > 1 ~ I ((1 $T SW > I� �CHRISTIAN Q 17 TH i al i ti Q 180TH ; Hs I PL SW ..,•• �..• S J :� - j 0 S 181ST. ST W> ° ST 18 ST PL SW > SW P Sw 0 s L �t 181 ST PL W I8 �Fi a OfPT 181 S �S� 182ND 3 82ND ST Q ro �'� Pl0 OF 183RD PL a a1183R ST 182 SW 183R °< 56 LICENSING > S rl Sw PL SIN . PL SW y3 r s '3 co > 18�--- P��� a o �� �h�tN 183RD. c303 a ~I W = j > 1 RD ^ 3 ` / �O� ¢ Z �^ I STSWIS� > ¢i a � L� _ > 184TH ST SW 06 y n n 1$5TH-' .. G 3 Q �y�� .. N o 185TH $T S Q = SNAKE ' > x i85TH ;� P� 185TH►- 3 PL 186TH rR, sr ry a m 'a S I W ST RD __ s�,N 3 = 1a6TH ST W = Z 186TH °- SW ���OR _� � t1 7TH~oI II��``p�j W - - — — 487-TH�W'AS-�- - - �n'�, -� . -�t¢PL SW cn1 .188TH- ST 41MI SPIRO RESIDENCE INTRODUCTION AUTHORIZATION for GEOTECHNICAL ENGINEERING page 1 of 67 pages In a contract dated 19 April, 1990, David Spiro [CLIENT] authorized HEMPHILL CONSULTING ENGINEERS [HEMPHILL] to conduct geotechnical engineering for the proposed [PROJECT] .to be located at 15631 75th Place West, Edmonds, as shown approximately in Figure 1. PURPOSE of GEOTECHNICAL ENGINEERING The purpose of the geotechnical engineering was to conduct a geotechnical investigation at the site of the proposed PROJECT, and to prepare a geotechnical report. PURPOSE of GEOTECHNICAL INVESTIGATION The purpose of the geotechnical investigation at the site of the proposed PROJECT was to determine the stability of that portion of the site that would affect the proposed structure, to determine the soil conditions for foundations, slabs, and paving, and to determine the groundwater conditions for drainage. PURPOSE of GEOTECHNICAL REPORT This report was prepared for the following purposes: a. To present information to the CLIENT to understand the geotechnical portions of the PROJECT. b. To present the results of the geotechnical investigation and testing, and geotechnical designs of rockeries and piles. c. To present recommendations for the CLIENT, the architect, and the structural engineer to design the foundations, floor slabs, drainage, retaining systems, and paving, and to prepare specifications for construction control and verifications. HF:=MPH11 I FIGURE 2 PROPOSED HOUSE -, p- . . . . ............ SPIRO RESIDENCE page 2 of 67 pages d. To present some limited information to the contractor to determine some anticipated site conditions, to present some construction requirements and possible changes to be determined at the time of construction, and to help the contractor establish some construction procedures. e. To aid the Building Department to establish an inspection program for the geotechnical portions of the PROJECT. F H 1 1 FIGURE 3 PLAN of PROJECT NZImirazz ITdIp SCALE 111 - 20' I o� \ •�roirr Tv.P � I ��� � �� 1 � I - El-tz:�41z= 40� ZD Vr1 � ' i tj HOUSE GARAGE .1 .,v,e ° ` z %/ f AV D/4r NN SPIRO RESIDENCE page 3 of 67 pages DESCRIPTION of PROJECT The PROJECT will be a single family dwelling located on the site as shown in Figure 3. The house will be a 3 story wood frame structure with an attached garage at the rear. Figure 4 on the next page shows the project in section. The house will be supported by grade beams that span between lateral resisting piles. The lateral resisting piles will be designed to resist lateral movement of potentially unstable soils under portions of the site. The garage floor will be a structural slab that spans between grade beams. Part of the garage structural slab will be located over a crawl space. The lower floor of the house will be supported by wood joists over crawl spaces. The wood joists will span between grade beams. A portion of the northeast corner of the house adjacent to the driveway will be designed as a soldier pile system to support a retaining wall on piles. The retaining walls will support the driveway and the back porch. A soldier pile retaining wall will be placed at the rear yard to support the excavated portion of the rear slope. A second story deck at the front of the house will be supported by spread footings. The deck will be designed to allow for some settlement and lateral movement. A spiral stair from the deck to the ground surface will be placed on a spread footing.. A rockery, shown in plan in Figure 3, will support a portion of the driveway adjacent to the house. The back porch will be supported by structural fill soils that will be supported by the retaining foundation wall. The drainage for the rear soldier pile wall will be constructed to intercept any groundwater from the slope and conduct it to the existing interceptor system. The rear portion of the existing interceptor system will be removed and a new system will be constructed behind the soldier pile wall. �0 iQ z —raw 1= z f cc p iNLL 0 t i i �r r-- L---� R w m CM V rL SPIRO RESIDENCE page 4 of 67 pages, RATIONALE for INVESTIGATION and RECOMMENDATIONS The request by the CLIENT for HEMPHILL to conduct geotechnical engineering, regardless of any specified charges, imposes the obligations implied by state and local building codes, and the State of Washington Registration Act for Professional Engineers, that all construction endeavors within the state be designed and constructed in such a manner as to protect the lives, health, and property of the public; therefore HEMPHILL is obligated to investigate and make recommendations concerning all phases of construction that would affect or be affected by soils and foundations, including groundwater and drainage. . , In accordance with those obligations, the extent of the geotechnical studies and recommendations, including the recommended future studies 'to be conducted at the time of construction, have exceeded the generally accepted minimum standards to mitigate jeopardy to the lives and health of the public. The extent of the geotechnical investigation, including the subsurface explorations, any testing program, and engineering studies, have been modified in accordance with recommendations by HEMPHILL, and approved by the CLIENT, to reduce costs; therefore, in conjunction with that modified geotechnical investigation, to minimize possible property damage, the recommendations in this report include appropriate safety factors that correspond with the extent of that investigation, based on the requirement that the presumed subsurface conditions will be verified by HEMPHILL after the true conditions have been revealed by the excavations. NOTE: 'Presumed subsurface conditions' are assumed to be accurate based on the evidence that has been observed by visual examination, geologic research, and field testing, but, because of the nature of subsurface conditions, regardless of the extent of the investigation, the apparently obvious conditions are not always true, and the geotechnical engineer must always accept the evidence with some suspicion, and never be satisfied that the presumed conditions are accurate until those conditions have been verified by complete exposure and testing at the time of construction. The geotechnical engineer must present design and construction recommendations that are as realistic as possible without excessive costs for the investigation and design, but that will also not require extensive design changes if the soil and groundwater conditions are not as anticipated. HAM "I 1 FIGURE 5 VIEWS of HOUSE VIEW from NORTH SPIRO RESIDENCE page 5 of 67 pages ASSUMPTIONS for GEOTECHNICAL ENGINEERING The analyses, conclusions, and recommendations presented in this report are based on the following assumptions: A. That drawings and data furnished to HEMPHILL by the CLIENT are complete and correct. B. That the final plans and specifications will correctly include all the appropriate recommendations presented by HEMPHILL in this report. C. That other engineering that affects foundations, such as structural and mechanical, is correct, and correctly implements the geotechnical recommendations. D. That the proposed structure will be constructed in accordance with the plans and specifications, and any recommendations by HEMPHILL at the time of construction. E. That site conditions will not change due to unanticipated natural causes or construction operations at or adjacent to the site. F. That the subsurface investigation revealed conditions that are representative of subsurface conditions throughout the site. G. That data from visual observations and soil tests conducted in the. field correctly exposed all the critical physical properties of the soils, and that those tests closely I represent other soils that appear to be similar. H. That the assumed conditions presented in this report will be verified by HEMPHILL after the excavations have revealed the true nature of all the subsurface soils. I. That changes recommended by HEMPHILL at the time of construction will be correctly implemented. LIMITATIONS of GEOTECHNICAL INVESTIGATION and REPORT A. This geotechnical report is intended only for the use of the CLIENT as an aid to design and construct the specific PROJECT, and in the specific location, as described in this report. This report may not be used by any other person or firm, or for any other project, or for any other location on the described property. HAM H I I I FIGURE 6 VIEWS of HOUSE VIEW from WEST iiion: Ullmanrir iii.sonits so u Y-rrz----------ram-----------s't-----------fir-�, ---. SPIRO RESIDENCE page 6 of 67 pages B. The analyses, conclusions, and recommendations contained in this report were determined from presumptive soil values based on probing, penetration tests, and visual classifications conducted at the site and adjacent areas. The extent of the subsurface investigation was in accordance with recommendations by HEMPHILL, and approved by the CLIENT, to limit the cost of the geotechnical investigation in favor of verification of the presumptive soil values, and control of materials and construction methods, at the time of construction. C. The recommendations presented in this report are based on the requirement that the presumed subsurface conditions, and the presumptive soil properties, will be verified by HEMPHILL after the true nature of all the soils and the groundwater have been revealed during the excavating process. D. Some of the subsurface data presented in this report contains presumed information that is satisfactory for design purposes, but is not necessarily factual data throughout the entire vicinity of the proposed project, therefore the subsurface and testing data should not be made available to prospective contractors for bidding purposes, or to the contractor for construction purposes. E. The recommendations in this report present options for design purposes that could be misleading to a prospective contractor. Only the final accepted options should be made available to the contractor so that rejected options are not inadvertently included into the construction. Also included in the recommendations are construction options that should only be determined or approved by HEMPHILL at the time of construction. GEOTECHNICAL INFORMATION for the CONTRACTOR REVIEW of the GEOTECHNICAL REPORT by the CONTRACTOR The contractor, and any prospective contractors bidding on the PROJECT, should be made aware that some of the subsurface conditions in the vicinity of the PROJECT were presumed, and that those presumed conditions were sufficient to prepare this report, but are not necessarily accurate throughout the entire vicinity of the PROJECT, and that the presumed conditions will be verified by HEMPHILL at the time of construction, and that any adjustments of foundations and drainage, or any other changes determined by HEMPHILL to be necessary to achieve a safe, properly functioning, or less costly structure, will be made at that time. SPIRO RESIDENCE page 7 of 67 pages The contractor may review this report to become familiar with the soil conditions that are anticipated by HEMPHILL, and to also become familiar with some possible methods, procedures, and options recommended by HEMPHILL. The contractor should be aware that some design options presented in this report might not have been appropriate for the final design of the project, and might have been rejected by the design team and/or the building department. This report is not intended to be included as part of the plans and specifications, except those sections specifically referred to by the design team, but is intended to present information only. OPTIONS for the CONTRACTOR As described in this report, the contractor might have options for foundation and drainage design, construction methods, and materials. Any options must be approved by HEMPHILL prior to the preparation and/or placement. GEOTECHNICAL INSPECTIONS The plans and specifications should include any requirements for the contractor to inform HEMPHILL to inspect or verify conditions at the time of construction, and to correctly implement any changes recommended by HEMPHILL. The contractor must understand that if special inspection is required by the building department, or by the owner, that verifications of existing conditions, and of construction methods and results, and of approvals of materials, becomes the absolute responsibility of HEMPHILL. Inspections and testing must be conducted prior to the placement and/or cover of conditions and materials, and HEMPHILL will not approve conditions and materials that have not been properly observed and/or tested. If the required inspections and testing are not conducted because of the contractor's failure to request inspections and testing at the proper time, then the requirement of more sophisticated testing, or of excavating to expose the required materials and/or construction, could be very costly. The contractor should communicate with HEMPHILL prior to the start of construction to clarify the inspection requirements, and to discuss any options for construction procedures and materials. HEM P H I LL FIGURE 7 i&°.ld'/I'"f TOPOGRAPHIC PLAN of SITE 1vfdm*�'l4Z,f AM SPIRO RESIDENCE SITE INVESTIGATION EXISTING SURFACE DESCRIPTION page 8 of 67 pages Figure 7 shows a topographic plan of the existing site. The contours show the Spiro property to be a gully with the head of the gully at the east side of the property. The site rises steeply 6 feet above Meadowdale Road, then is level for 80 feet, then rises 18 feet to a 25 foot bench, then rises steeply at angles ranging from 30 to 50 degrees for approximately 100 feet before the slopes become gentle. Figure 7 shows an interceptor drainage system at the toe of the lower slope that then drains to a drainage system in Meadowdale Road. All of the lower slope and the lower level area is grass covered. The steeper rear slope is mostly shrub covered with some trees. SUBSURFACE INVESTIGATION RATIONALE for INVESTIGATION The request by the CLIENT for HEMPHILL CONSULTING ENGINEERS to conduct geotechnical engineering obligates HEMPHILL to investigate and make recommendations concerning all phases of design and construction that would be affected by soils and foundations, including groundwater and drainage. The subsurface investigation was established in accordance with minimum standards established by HEMPHILL, and also with generally accepted minimum standards determined by other geotechnical engineers. Those standards were derived through experience that has proven reasonably often to reveal the true subsurface conditions throughout the sites of most projects. The extent of the subsurface investigation was based on the cost limitations recommended by HEMPHILL, and approved by the CLIENT, with the requirement that the presumed subsurface conditions would be verified by HEMPHILL after all the true subsurface conditions have been revealed by the excavations and drilling for cast in place piles, and that any necessary adjustments in foundation design and/or depth of pile placement for bearing and lateral stability will be determined by HEMPHILL at that time. FIGURE 8 GEOLOGIC MAP of VICINITY : Qols �• ' Old landslides 77777' \ s \ Large sthat occurred during the ablation of the `. Is Lobe of the Voshon ice sheet by lowering >. ,_ f � t • � .�`, of water -table level. Slides may have been active since original movement; tacks evidence i 1 f. f I 4.`q "•� of recent movement. Q�v Voshon recessional outwash Al r 1 Light -brown loosely compacted sand and gravel. Dry 'r.si!, _sue'. • •• •• " gravel seeks angle of repose of 35°; wet gravel s yJs ) - ,•;1 - i�. will stand in near -vertical cliff. Sorting varies; particle size varies from medium sand to cobbles. �. Stones c re usual) covered with a li ht-brown •€ .� -r- j.•dusty oaring and are well rounded from stream A s$'S �} Tt"s, `, r r' i a - `.'J transportation. Contains some ice contact deposits. • f:•• i r tt 1._ .t r Vashon till f !S Poorly sorted, rsonstratified lodgment till deposited as ground moraine. Mixture of clay, sill, sand, peb- - P ! f •� •• i les and cobbles with occasional ulder . :• 9# es 1large boulders. b t Appears gray to blue on fresh surface; may weather to brown or yellow. Exlremely compact, will stand in near -vertical cliffs; generally lacks surficiol cracks or joints. Stones are subngular to rounded. r -,) • L F I i +• Some larger clasti show striations and focetfng, Vertical faces somef;mes spoll off in large blocks. Some areas of Ow ore covered by a thin veneer of Qv r i loosely consolidated, no sorted ablation fill and(or) i thin outwash. Vashon advance outwash Fresh, light -gray, stratified, compact sand and gravel. Will stand in near -vortical cliff. Sorting varies; j 1.4 particle size varies from fine sand to coarse pebbles, ` s ',%�,r ( f• ' J�f r d lit a y ,� � t ° 7 si > � ♦ s t Es eronce Sand Thinly bedded (From 2 to 6 inches), fresh, light -gray sand layers. Particle size varies From medium to coarse sand (with 10the percent pebbles); small bias often occupy the base of each individuall bed or tens. Occasional lenses of coarse gravel occur, Usually sloughs to angle of repose an exposed slopes. t is f� .. f // r✓/r ! l� ' j e j I t eFF •"( s Whidbey Formation General) medium -bedded (2 to d feet) sand, silt, and J \ # ft ( r 1 ( ! clay. Color varies From light brown to gray. Par- ticle size varies from clay to coarse sand with a ; f f €� tt ° few lenses of small pebbles. Sorting is generally V ' J` t „^' _ ••„ t % ry s 1# good within each individual bed. Clay and silt beds can be as thin as 2 Inches. Non lacial river deposits. May flood -plain lain de show tectonic deforma- /'•�lilt ' ! f �° \(, ,J 1 a� ! jdt L'R1 T` t'+1l�•(.�r"'i { t tion. .. �+.«,..K�k, �, i��V 'r;1 � � � ,�w.,�,. ,,.�.. � � to � � ��: M � 'a� ;.y.',• �y( odb Double Bluff Drift •• ,,}}I Jill .AN/-ro-rv«Contains: (1);ron-oxide cemented gravel, consisting of fill smalito medium pebbles well cemented in a grit matrx; (2) Pebbly9locfolocustrine s111s; and (3) ""v' beds of sand and ravel. •••" �' ,fit /;,��+�•P•".;�g +(. f massive %;It and lesser g At, Well compacted and will stand in a neat -vertical ✓ i s t a s, rI t u a+ cliff. Pebbly display %fits dis Ia desiccation cracks at F ? ! �t ♦ „Mf........ •...y:: .f. ,�,{ E ,! ; f ,',� i2k 3! / the surface. May show tectonic deformation. i SPIRO RESIDENCE page 9 of 67 pages There have been several investigations conducted in the general vicinity of this proposed project. "rhe subsurface investigations for those projects have revealed conditions similar to the conditions at this site. Therefore, the subsurface investigations, the foundation treatments, and the results of those other projects have been studied in conjunction with this project. METHODS of INVESTIGATION The presumed subsurface conditions at the site were determined by historical research, geologic research, shallow probing, field tests conducted at the site and adjacent areas, and visual observations at the site and adjacent areas. HISTORICAL. RESEARCH The general area is known as the 'Meadowdale Slide Area' because of a series of slides that have occurred in the vicinity. The largest recorded slide occurred in 1945 when large movements occurred in this gully, and in the larger gully to the south. At that time all of the homes in the vicinity were on septic systems, and all effItjent and stormwater was infiltrated into the ground. Since that time sewers have been installed and septic systems disconnected, and some drainage was installed but not under the guidance of an expert. GEOLOGIC RESEARCH Geologic research conducted by HEMPHILL and others in the general vicinity of the site revealed that the geologic conditions at the site are fairly typical of the Puget Sound area. Figure 8 is a partial copy of one of the geologic maps of a portion of the Puget Sound area, which shows that the general vicinity of the site is at the intersection of the Esperance Sand and the Whidbey Clay. Descriptions of the geologic symbols are also shown on Figure 8. . The geologic maps do not have great accuracy, but they help to show soil types that are probable at the site but are not always obvious, or they help to verify that observed soils are as suspected. The significance of the geologic maps is that they show a general trend of geologic conditions that would appear to be reasonably continuous. Geologists have determined that as the Vashon Glacier moved south during the last glacial period, it blocked off the Straits of San Juan Fuca. Stormwater runoff from the mountains, and any meltwater from the glacier, became entrapped within the Puget Sound area. Therefore the entire Puget Sound area became a large lake. At that time Puget Sound extended from the Cascade Mountains to the Olympic Mountains, with the outlet to the ocean through the Chehalis Valley. H E M P H I L SPIRO RESIDENCE page 10 of 67 pages Sift and clay that eroded from the glacier, and also from the Olympic and Cascade mountains, created a muddy lake. As the clay and sift settled to the bottom of the lake they created the Whidbey Clay stratum that is approximately 80 feet thick in some places. The geologic map shows the Whidbey Clay with the symbol Qw. Some geologists believe that the Whidbey Clay is also the. Lawton Clay identified south of the site. Other geologists believe that the two clays have different origins. Their origins and differences are not important for this investigation. As the glacier moved south, its outwash deposited combinations of coarse silt, sand, and gravel on top of the Whidbey Clay. The sandy layer is named the Esperance Sand, and is 100 feet thick in some places. The geologic map shows the Esperance Sand as Qe. The glacier eventually entered the Puget Sound area and gouged out some of the presently existing valleys, including Puget Sound, Lake Washington, and Lake Sammamish. . As the estimated 3000 to 4000 foot thick glacier sat in the Puget Sound area, it plastered much of the ground surfacewith glacial till, which is composed of various combinations of clay, sift, sand, gravel, and cobbles. That soil, called Vashon Till, Qt on the geologic map, ranges in thickness from S to 100'. The over riding glacier than compressed all the underlying soils to great densities by exerting stresses of approximately 200,000 psf. As the ice melted and the glacier receded, sand and gravel that had been entrapped in the ice was loosely deposited over portions of the Puget Sound area by the outwash. That soil is designated as Qvr on the geologic map. VISUAL OBSERVATIONS at the SITE and VICINITY HEMPHILL has observed the Whidbey Clay from below the level of Puget Sound to elevations of approximately 150 feet. The Whidbey Clay is exposed in the steep slope along the east side of the property, and north and south of the site. Overlying the Whidbey Clay is the Esperance Sand, and often at that elevation groundwater seeps from the slope, and there is often evidence of instability. The soils overlying the Whidbey Clay between the steep slope and Puget sound is composed of loosely deposited sift and sand with small chunks of hard laminated clay that apparently was eroded from the steep slope. Those soils appear to be beach deposits that might have resulted from wave action, both eroding the rear slope and depositing the soils as a beach. The water might have been trapped between the receding glacier and higher ground, or Puget Sound might have been higher at that time. The beach deposits are overlain by sift and clay in some places where the slopes are more gentle, possibly from lacustrine (lake) deposits during periods of calm water. FIGURE 9 LOCATIONS of FIELD TESTS tiIfADDiYD,4lf f�D,JD 10 1 I O BORINGS IN o NN ell TEST PITS —'---------4-f---ram-- '��� o. o I SPIRO RESIDENCE FIELD TESTS TEST PITS page 11 of 67 pages 2 test pits were conducted, located approximately as shown in Figure 9. The test pits were conducted to locate the hard clay below the loosely deposited silts and sands. HEMPHILL conducted field penetration tests within the exposed undisturbed soils in the test pits to determine the approximate strength characteristics and other properties of the potential foundation soils for, the house and the proposed soldier pile retaining wall and/or other type retaining wall to be determined after the grading has revealed the true soil conditions along the upper bench along the east side of the site. Logs of the test pits are shown in Figure 10. The logs show visual descriptions of the soils, depths of changes in the soil types, groundwater observations, and any other pertinent observations or field tests. FIGURE 10 LOGS of TEST PITS depth TEST PIT 3 1 MEDIUM 2 DENSEM LEGEND: 3 RUSTY ------------- DISTINCT CHANGE BETWEEN SOIL TYPES xxxxxxxxxxxxx GRADUAL CHANGE BETWEEN SOIL YYPES 4 SILTY a=�===______= BOTTON of TEST PIT 5 GRAVELY • TOP of FREE GROUNDWATER 6 SAND 7 8 HARD GRAY 9 SILT and CLAY 11 12 13 NOTE: 1. TEST PIT SILT AND 14 CLOSER TO 15 2. NO FREE G TEST PIT 4 ---------------- MEDIUM DENSE RUSTY SILTY GRAVELY SAND 3 ENCOUNTERED HARD GRAY CLAY AT A HIGHER LEVEL THE SLOPE ROUNDWATER WAS ENCOIINTFRFD depth --0-- 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 SPIRO RESIDENCE page 12 of 67 pages TEST BORINGS A. TEST BORING LOCATIONS 2 test borings were conducted, located as shown in Figure 9. The locations were chosen to determine foundation conditions for the proposed house, and to study slope conditions. B. BORING EQUIPMENT The borings were conducted using a truck mounted hollow stem continuous flight auger, similar to that shown in Figure 11. FIGURE C. BORING LOGS TRUCK MOUNTED AUGER Figures 12 and 13 on the next page show the logs of the test borings. The logs were compiled by combining the field notes of the geotechnical engineer, field test data, and visual classifications of recovered soil samples. HE M, P H ILL FIGURE 12 NTH COLOR CONSISTENCY LOG of BORING 1 DESCRIPTION of SOILS MOISTURE COMMENTS GY HARD VERY FINE SANDY SILT DAMP 9000+ (FILL?) i?????????????????????????????????????7????????????????????????????????????????????????????????????????????????? GRAY MED DENSE VERY FINE SAND & FINE SAND WET SOUPY FROM SAMPLER GRAY MED DENSE VERY FINE SAND & FINE SAND WET 5000+ i???????7??????????????????????????????????????????????????????????????????????????????????????????????????????? GRAY HARD CLAYEY SILT DAMP 9000+ SPT DEPTH 18 3 14 8 10 13 26 18 GRAY HARD CLAYEY SILT DAMP 9000+ 41 23 L E G E N D----------- DISTINCT CHANGE in SOIL DESCRIPTION GRADUAL CHANGE in SOIL DESCRIPTION ??????????? LOCATION of CHANGE NOT ENCOUNTERED in SAMPLE * * * TOP of GROUNDWATER +++++++++++ BOTTOM of BORING SPIRO RESIDENCE FIGURE 13 LOG of BORING 2 DEPTH COLOR CONSISTENCY DESCRIPTION of SOILS BROWN LOOSE GRAVELLY SAND 5 BROWN and GRAY and MED DENSE SILTY.FINE SAND RUST 10 BROWN 8 GRAY MED DENSE COARSE SILTY FINE SAND 15 MOISTURE WET FILL page 13 of 67 pages COMMENTS WET CHANGE NOT LOCATED WET SPT DEPTH 8 3 0 7 7 8 0 9 4 13 BROWN 8 GRAY MED DENSE COARSE SILTY FINE GRAVELY SAND WET 14 18 20 GRAY FIRM VERY PINE SANDY SILT WET 3000+ 12 23 25 GRAY HARD SILT DAMP YUUD+ L4 do 30 GRAY HARD SILT DAMP 9000+ (LAYERS DIPPED 30 DEG) 40 33 34+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ L E G E N D ------ DISTINCT CHANGE in SOIL DESCRIPTION GRADUAL CHANGE in SOIL DESCRIPTION ??????????? LOCATION of CHANGE NOT ENCOUNTERED in SAMPLE * * * TOP of GROUNDWATER +++++++++++ BOTTOM of BORING SPIRO RESIDENCE page 14 of 67 pages r D. FIELD TESTS Standard Penetration Tests, as described by ASTM D 1586, were conducted within the test borings at the depths shown on the boring logs. FIGURE 14 STANDARD PENETRATION TEST 140 Le DRIVE HEIGHT FREE CONTINUOUS AUGER SING 1.• P IT TUBE. SAMPLER In UNDISTURBED SOIL %�'i •' As shown in Figure 14, the Standard Penetration Test is conducted by dropping a hammer weighing 140 pounds a distance of 30 inches to drive a split spoon sampler into the soils below the auger. The number of blows from the hammer required to drive the split spoon sampler 12 inches into the undisturbed soils is called the Standard Penetration Test. r -FIGURE 15 SPLIT SPOON SAMPLER /HARDENED SHOE BALL CHECK I [��yIIlllllll� 1 SPLIT TUBE FIGURE 1 IIViERCEPT.OR DRAINAGE �lilf,4DDfYD,4lf /ew 11, IS O lo � � _ \ rr� •sue i; . r-.. I �/.i ���� !f 1 a � I 1 �/: Z?c': 6i� Ile J, w .- /�2 0. SPIRO RESIDENCE page 15 of 67 pages The split spoon sampler, shown in Figure 15, is designed with a precisely beveled 2 inch diameter driving shoe that screws on the end of a split pipe. The split pipe can be opened to recover a soil sample that is driven into the pipe during the Standard Penetration Test. The geotechnical engineer can use the Standard Penetration Test data in conjunction with the visual classification of the soil sample recovered from the split spoon sampler to estimate the relative density of cohesionless soils (granular), and the consistency of cohesive soils (clayey). E. RECOVERED SAMPLES a. Disturbed Samples Samples of each Standard Penetration Test, located at depths as shown on the boring logs, were recovered from the split spoon sampler for visual classification by the geotechnical engineer. b. Undisturbed Samples Undisturbed samples were not recovered for laboratory testing. Because of the wet sandy nature of the upper sandy soils, undisturbed samples would have been difficult, if not impossible, to recover' and. prepare for undisturbed testing. Those soils will not support the pile foundations, and therefore some of the physical parameters of those soils are not important. Stability studies within those soils will presume those soils in a worst condition than presently exists. The physical properties of the hard clay can be related to the Standard Penetration Test, and to experience with those soils. The tests necessary to determine the soil modulus of the hard clays for pile design cannot be conducted by any feasible means, therefore those design parameters will be conservative. Some field observations and testing will be conducted to verify the accuracy of the pile designs. GROUNDWATER OBSERVATIONS Groundwater seeps from the sand/clay intersection higher on the slope, but there is no evidence of any affect on this site. Some groundwater is intercepted by the drainage system shown in red in Figure.16. The volume of flow from the system is small. The source of the seepage was not determined, but appears to be from the adjacent property to the north. Soils above the clay in the test borings are wet, indicating that groundwater lays and/or seeps on top of the clay. FIGURE 17 CAPILLARITY HEIGHT of CAPILLARY RISE FOR VARIOUS SOIL GRAIN SIZES. B U. S. STANDARD SIEVE SIZE 3" 1.5" 3/4" 3i8" No.4 10 20 40 60 100 200 100 100 to 90 V C BO W N 70 } 60 Q 50 J a 40 Q U 30 w 0 �.. 20 C3 10 W Z 0 90 Bo 70 60 50 40 50 20 10 0 1000 100 10 1.0 0.1 0.01 0.001 GRAIN SIZE IN MILLIMETERS COBBLES GRAVEL SAND SILT OR CLAY COARSE FINE COARSE MEDIUM FINE NOTES: A. HEIGHT OF CAPILLARY RISE SHOWN IS TO TOP OF SATURATION; CAPILLARY WATER CONTINUES TO RISE AT LESS THAN SATURATION. B. "1310 SIZE" IS GRAIN SIZE OF SOIL WHERE 10% OF SOIL IS FINER. N d L v C W (n FE cc g J FL Q U 0 F- 2 C3 W SPIRO RESIDENCE page 16 of 67 pages Groundwater seeps from the slope on the property west of Meadowdale Road at the first bench above the railroad tracks. Further studies will be conducted during the grading operations, and during the placement of an interceptor trench behind the west soldier pile wall at the base of the steep slope along the east side of the property. There was no evidence of groundwater or seepage erosion at the site or the general vicinity at the time of the investigation. Groundwater is water below the ground surface that can seep in the direction of gravity flow. For example, if a hole is excavated and water seeps into the excavation, that seeping water is groundwater. Although the soils above the seepage zone are wet or damp, that water is held like a sponge by the soil by capillarity and therefore does not seep. Because of the fine grained nature of clay, silt, and fine sand, the pores hold water much as a sponge does. Water will not run out of those soils until the weight of the water is equal to the force of capillary tension. That height of water is similar to the height that a towel can suck up water from a tub. The finer the weave of the towel, the higher the water rises. Similarly, the finer the soil grains, the higher the water rises in the soil above the normal groundwater level, as shown in Figure 17. At this site surface water that infiltrates the upper granular soils will stop at the undisturbed hard Whidbey Clay and then will build up as groundwater to a depth depending on the height of entrapment, and the rate of seepage from the site. Capillary water will then rise above the top of the groundwater to the height that the finest soils are capable of holding the water; as shown in Figure 17. Soils- above the groundwater level that have capillary water are generally stronger than soils below the groundwater level because the capillary water bonds the soil grains together like a weak 'glue'. When the soils are saturated, as below the groundwater level, then the capillary bond is broken and the soil loses that source of strength. The capillary bond is a part of the strength of a soil called cohesion. As the groundwater rises more soils can lose the cohesive strength and the stability of the site will be reduced. The stability investigation will be discussed in the next paragraph, and stability studies will be presented later in the report. u 00 TOO 0 M d U. Z m w .. . ................ .. fn 0 :. LLI � a ... O ¢ so a w r I I I I • .............. .... ................. i ....... . �.:.. I aN. � O C01 r0 CD h � r *- 0 N u w Q Q m Q U) r SPIRO RESIDENCE page 17 of 67 pages SITE STABILITY INVESTIGATION Since the area is being studied for stability, HEMPHILL investigated the lower slope west of Meadowdale Road to Puget Sound, shown in Figure 18. The slope was measured with inclinometer and range finder. The slope from Meadowdale Road to the railroad ranges from 15 to 25 degrees at a slope distance of approximately 2601. Most of the slope is covered with blackberries, shrubs, and small trees. The shape of that slope appears to be a continuation of the gully that begins on the Spiro property, with some changes in the slope to construct Meadowdale Road, and to construct the railroad. SOIL DESCRIPTIONS HOW PHYSICAL PROPERTIES of SOILS were DETERMINED The physical properties of the existing undisturbed natural soils at the site were determined from visual descriptions combined with manual penetration tests conducted on the undisturbed soils exposed in the test pits, and on samples recovered from the test borings. Undisturbed samples of the soils at the site were not recovered for testing, since the estimated minimum strengths and compressibilities of the approved supporting soils exceeds the required maximum strengths and cornpressibilities for piles, soldier piles, and for temporary support for grade beams, and minimal requirements for deck footings and rockeries. Other properties, such as permeability and organic content, were obvious, and were either insignificant, or could be contrrlled. The allowable supporting soils that HEMPHILL observed at the site are reasonably similar to other soils that have similar visual descriptions, hand penetration tests, and standard penetration tests. The physical properties of those similar soils have been determined by HEMPHILL and others from construction experience, from elaborate field testing, and from specialized laboratory testing. Also available are publications that list the approximate physical properties of those similar soils related to their visual descriptions. Therefore HEMPHILL estimated the properties of the natural undisturbed soils at the site to be approximately equal to the recorded properties of similar soils. SPIRO RESIDENCE , . page 18 of 67 pages DESCRIPTION of UNDISTURBED NATURAL SOILS The following descriptions and range of physical properties are general knowledge of the typical soils, but are not necessarily the physical properties determined by HEMPHILL for the soils at this site. The actual design values used by HEMPHILL will be presented later in this report. WHIDBEY CLAY The Whidbey Clay is composed of various combinations of clay, silt, and very fine sand that were deposited in calm waters of the lake that existed in the Puget Sound area as the glacier advanced. Since the lake waters were calm, the fine grained soils were laid fairly level. The glacier eventually sat on the Whidbey Clay and compressed it to great densities and strength. Where the Whidbey Clay is exposed on slopes, it is usually stable, and seldom has deep seated slides. Any instability generally occurs in the soils that rest on the clay, or within the upper weathered clay that results from freezing and thawing, wetting and drying, and root action. The Whidbey Clay sometimes has weak surfaces called slickensides that were created when the loads of the accumulating soils, and/or the glacier, caused the soft clays to shift down in one place and up in another. The movement was usually circular and occurred in a small area. The movement created a slide. plane where the soil grains became permanently aligned, even after being greatly compressed by the glacier. The slickensided surfaces cause chunks of Whidbey Clay to fall out of exposed surfaces and in excavations. The slickensided surfaces seldom cause deep seated slides, and have very little effect on vertical bearing capacity, compressibility, and permeability. The Whidbey Clay sometimes contains vertical relief cracks where it is exposed along some slopes that were carved by the glacier or other erosion after the clay was compressed. The relief cracks were the result of the removal of great loads that once contained the Whidbey Clay laterally prior to the removal of the soils that were once adjacent to the slope. The relief cracks can exist for great distances into a hillside, depending on the extent of, the lateral pressure of the removed soils. Water seeps into the cracks and softens the soils, creating weak joints. The weak joints and hydrostatic pressures in the joints can cause deep seated slides in the Whidbey Clay, and can also cause the Whidbey Clay to fall off steep slopes in chunks. That type of failure generally occurs where the slope is adjacent to wave action or running water that constantly washes away any accumulation of slide or erosion debris at. the toe of the slope. If the debris can accumulate, the build up will eventually cover the slope and will provide lateral support, and also protection against weathering. SPIRO RESIDENCE page 19 of 67 pages The undisturbed Whidbey Clay generally has bearing strengths of 6000 to 8000 psf, has very low compressibility, low permeability, a friction factor of approximately 0.2 to 0.3 (depending on the other material involved in sliding), and side friction on piles of 1000 to 2000 psf (depending on the pile material, and the initial pressure when the pile is placed). The undisturbed glacially compacted Whidbey Clay can be confused with Whidbey Clay that has been disturbed by weathering, sliding, and rebounding and cracking from relief. The undisturbed Whidbey Clay can also be confused with sifts and clays that were deposited in the glacial lake as the glacier receded, and therefore were never over ridden by the glacier. The Whidbey Clay can also be confused with stream, river, and lake deposits that occurred since glacial times. Because of the great difference in physical properties between the undisturbed Whidbey Clay, and either disturbed Whidbey Clay or other clays, only a geotechnical engineer should evaluate the physical properties of any clay or silt type soil. ESPERANCE SAND The Esperance Sand in its undisturbed condition exists farther up the slope and has no effect on this site. Esperance sand has been eroded from the upper slope by stormwater runoff and groundwater seepage, and has been deposited at the site. The source of some or all of the upper loose soils at the site could be eroded Esperance Sand, but those eroded soils would not have the same properties as the undisturbed glacially compacted Esperance Sand. Following is a description of the undisturbed Esperance Sand, how it was formed, and its its properties and why it poses no effect on this site, and how it got to the site. The Esperance Sand is composed of various combinations of sand, silt, and gravel that were deposited in the glacial lake by the Vashon Glacier. Since the grains of the Esperance Sand were heavier than the Lawton Clay particles, they settled faster into the glacial lake, and were therefore deposited closer to the advancing glacier. The more slowly settling clay particles were carried farther away from the glacier. Therefore, as the glacier advanced, the Esperance Sand was deposited on top of the Lawton Clay. The advancing glacier eventually compressed the Esperance Sand, and also the underlying Lawton Clay, to a very dense condition, therefore the Esperance Sand in its undisturbed condition is very strong, and seldom has deep seated slides unless it is loosened by weathering or undercut by erosion. Those soils would slide farther up the slope in thin layers and generally remain close to their source, therefore the undisturbed Esperance Sand is not likely to pose a threat to the Spiro house. Weathering, which is caused by wetting and drying, freezing and thawing, and root action, loosens the surface of the very dense Esperance Sand, and causes the surface to lose strength. SPIRO RESIDENCE page 20 of 67 pages The loosened sand will slough to the base of the slope, which is farther up the slope where a bench has been created, and the slope is gentle, from past sloughing. The weathering and sloughing process can continue, with the loosened soils building up the slope at their natural angle of repose, until the entire slope is covered with sand at the natural angle of repose of the weathered soils. The underlying undisturbed sands are then protected from weathering, and the slope is then stable. The undisturbed Esperance Sand is easily eroded by runoff and streams, and also by seeping groundwater which generally occurs where the intersection of the Esperance Sand and the Lawton Clay is exposed on a slope. Stream action at the base of the slope, and/or groundwater seepage on top of the Lawton Clay, can erode the base of the Esperance Sand, and then undercut the upper slope. That undercutting process causes the eroded sand to slide to the base of the slope. If the sloughed . sands at the base of the slope are not carried away by stream or wave erosion, then the eroded sands will build up the slope, and will eventually cover the seepage zone, and will prevent the seeping water from eroding the overlying sand. Wave action has apparently prevented the build-up of the sloughed sand at this site, or the weight of the sloughed soils caused the soils in the gully to slide out toward Puget Sound. Disturbed Esperance Sand that has been loosened generally has a natural angle of repose that ranges from 35 to 40 degrees, depending on the grain size and the cohesion of the finer soils. RECESSIONAL GLACIAL OUTWASH & BEACH DEPOSITS Recessional glacial outwash & beach deposits are generally composed of any combination of silt and fine sand to coarse gravel that either washed out of the glacier as it receded, or eroded from the slopes. Recessional glacial outwash and beach deposits were loosely deposited by running water, or within an entrapped glacial lake, and were never over -ridden by the glacier. Glacial outwash and beach deposits generally have a natural angle of repose that ranges from 25 to 45 degrees, depending on grain size, groundwater conditions, and some binding by silt. Glacial outwash and beach deposits are generally fairly pervious, therefore stormwater infiltrates easily. On slopes where stormwater does not infiltrate, or where concentrated uncontrolled runoff occurs and the surface is not protected by vegetation, erosion can be very severe. z O LU cn ♦V V 0 O 'LJJ V LU Q W 0) T" ul m D a U. in w U w 0 0 r � U - w . ........ .... 0 CC d� N Full N. 4 _ I ztp W�. a - N -- U a. ............ ... ......... W: . • a. a . . ._ _ Om . a (n 0 N 11 w a D v m Z NO Q J WLL N m t W f- N W0 a:Z > 0 CO W g" UW 0� � J Q J_ �Z oa H 0 c as = W Ncc rr W Q Z W ZN OO CC r CV fA W f.. z SPIRO RESIDENCE page 21 of 67 pages Groundwater is often encountered at the base of glacial outwash and beach deposits where the underlying soil is less pervious, such as at this site where the underlying soils are the Whidbey Clay. If those conditions occur on a slope, high saturation at the base of the granular soils can cause unstable conditions. The bearing capacity of granular glacial outwash and beach deposits have a wide range, depending on the composition of the soils, the depth, the size, and the shape of the footing, and groundwater conditions. Generally loosely deposited granular soils with some silt, that has settled under its own weight, that has been water settled, and that has had time for desiccation, can support loads in excess of 2000 psf with minimal settlement. Frictional resistance to sliding between the granular soils and structural components ranges from approximately .3 to .6 times the vertical load. Lateral loads on retaining walls and rockeries can range from very high for soupy silty sands during unusually wet conditions, to nearly 0 for more granular very pervious soil capable of supporting itself. CONCLUSIONS The site has been unstable in the past, but according to the neighbors there has been no noticeable movement since 1947. The property west of Meadowdale Road .has many undulations that could indicate some movement; but it could also be the result of grading and filling. The lower bench just above the railroad has a seepage zone,'but the slope at that location is gentle, and there is no evidence of movement. The seepage could be occurring on the top of the hard Whidbey Clay. Figure 19 shows that the steep rear slope of the Spiro property is the hard Whidbey Clay overlain with weathered clay, and possibly some slough debris from higher on the slope. Because of the great strength of the undisturbed Whidbey Clay, a deep slide in the steep rear slope is unlikely. Any instability of that slope will be the result of minor surface sloughing. There is no evidence of slough soils on the bench at the base of the steep slope. The test pits revealed that the bench at the rear (east) of the property is composed of various combinations of coarse sift, sand, and gravel. Those soils are partially cemented with a rust colored matrix, which fits the description of the Double Bluff Drift shown as Qdb on Figure 8 on page 9. Figure 8 shows the Double Bluff Drift in the vicinity of the site. It appears that the Double Bluff Drift might be a recessional outwash that was deposited against the steep slope by the glacier as it receded. The test pits show that the Double Bluff Drift is directly over the hard Whidbey Clay. Figure 19 shows the estimated location of the Double Bluff Drift. H E M P I --I I L L SPIRO RESIDENCE page 22 of 67 pages The test borings show that the loosely deposited fine granular soils with the small clay chunks are directly over the Whidbey Clay. There is no evidence of the Double Bluff Drift in the test borings, therefore that soil apparently makes up the bench and stops at its natural angle of repose on top of the clay. Therefore that soil was in place before the `beach deposits" were deposited. Some of the Double Bluff Drift was probably eroded by wave action and became part of the beach deposits. The test borings show that the top of the clay slopes down to the west, and probably continues to the seepage zone at the base of the slope just above the railroad tracks. Figure 19 on the previous page shows the estimated location of the hard Whidbey Clay. Some groundwater enters the interceptor drains located at the base of the bench, but the water apparently comes from the property to the north, since no water enters the system at the base of the bench. That interceptor pipe might not be deep enough to intercept water that seeps on'top of the clay. Groundwater that can seep is located near the top of the hard clay. There is no evidence that the water surfaces before the lower slope on the property west of Meadowdale Road. Figure 19 on the previous page shows the estimated location of groundwater. Nearly all the soils at the site will hold capillary water, which will be discussed later in the report. Soils that have capillary water will be stronger and more stable than soils that are below the seeping groundwater level FIGURE 20 MAP of SEISMIC ZONES 3 LEGEND Zone 0 — No damage l 3 Zone 1 — Distant earthquakes with fundamental periods greater than 1.0 seconds may cause minor damage. Corresponds to intensities V and VI on the Modified Mercalli intensity scale. Zone 2 — Moderate damage; corresponds to intensity VI on the Modified Mercalli intensity scale. Zone 3 — Major damage; corresponds to intensity V I I I and higher on the Modified Mercalli intensity scale. Seismic zone map of continental United States (After Algermissen, 1969) Seismic Coefficients Corresponding to Each Zone. INTENSITY OF MODIFIED AVERAGE SEISMIC ZONE MERCALLI SCALE COEFFICIENT REMARK 3 0 — 0 No damage 1 V and VI 0.03 to 0.07 Minor damage 2 VII 0.13 Moderate damage 3 VII and higher 0.27 Major damage SPIRO RESIDENCE page 23 of 67 pages ENGINEERING STUDIES and RECOMMENDATIONS RATIONALE for RECOMMENDATIONS The geotechnical recommendations presented in this report for the proposed PROJECT are based partially on presumptions by HEMPHILL, and on the requirement that HEMPHILL will verify the presumed conditions, and will make final decisions for depth of piles, slope stability, any retaining systems, structural fill, slabs, paving, and for drainage, at the time that the excavations reveal the true nature of all the subsurface soils. SEISMIC STUDY HEMPHILL conducted an investigation to determine the potential for seismic vibrations to cause slope failures, resulting from increased lateral forces and reduced soil strengths, and from settlement, resulting from densiNing and liquefaction of soils. INCREASED LATERAL FORCES, Lateral forces are created by the lateral vibrations created by an earthquake. Those lateral vibrations accelerate to a maximum velocity, and then decelerate to zero, then reverse and accelerate to the maximum velocity again. The acceleration and deceleration of the mass of soil in the slope is caused by the lateral forces caused by the earthquake. Since a force causes a mass to accelerate, that seismic force causes the soils to move laterally, which can cause a slope failure if that additional force, along with the other driving forces that already exist on the slope, is greater than the strength parameters (friction and cohesion) of the soil that would resist slope failure. Figure 20 shows a map of seismic zones that lists the Puget Sound area as Zone 3, which can have earthquakes with intensities of VII or greater. Figure 21 on the next page gives descriptions of the intensities. Figure 20 also shows the average seismic coefficient for a Zone 3 classification to be 0.27. According to some publications, that number is low for poor soil conditions and high for good soil conditions. Some experts state that the seismic coefficients have no basis from experience, and therefore are arbitrary. HEMPHILL used a seismic coefficient of 0.15 for slope stability studies presented in the next section of this report, which is recommended by some local building departments. The source and accuracy of the recommendations is not known, but the values have been accepted as standards and are considered acceptable for engineering purposes. A higher value might be appropriate where a slide might be life threatening, which is not the case at this site. FIGURE 21 DESCRIPTIONS of SEISMIC INTENSITIES ABRIDGED MODIFIED-MERCALLI INTENSITY SCALE* I: Detected only by sensitive instruments. II. Felt by a few persons at rest, especially on upper floors; delicate suspended objects may swing. III. Felt noticeably indoors, but not always recognized as a quake; standing autos rock slightly, vibration like passing truck. IV. Felt indoors by rnany, outdoors by a few; at night some awaken; dishes, windows, doors disturbed; motor cars rock noticeably. V. Felt by most people; some breakage of dishes, windows, and plaster; disturbance of tall objects. VI. Felt by all; many are frightened and run outdoors; falling plaster and chimneys; damage small. VII. Everybody runs outdoors; damage to buildings varies, depending on quality of construction; noticed by drivers of autos. VIII. Panel walls thrown out of frames; fall of walls, monuments, chimneys; sand and mud ejected; drivers of autos disturbed. IX. Buildings shifted off foundations, cracked, thrown out of plumb; ground cracked; underground pipes broken. X. Most masonry and frame structures destroyed; ground cracked; rails bent; landslides. XI. New structures remain standing; bridges destroyed; fis- sures in ground; pipes broken; landslides; rails bent. XII. Damage total; waves seen on ground surface; lines of sight and level distorted; objects thrown up into air. *This scale is a subjective measure of the effect -.of the ground shaking and is not an engineering measure of the ground acceleration. SPIRO RESIDENCE page 24 of 67 pages The seismic coefficient is a mathematical convenience, which is the lateral acceleration of the soil mass compared to the vertical acceleration of gravity. The true acceleration used to calculate the lateral soil forces is 0.15 x 32 ft/sec/sec = 4.8 ft\sec\sec. The weight of the soil can be converted to mass (slugs) by dividing by 32 (acceleration of gravity), and then the soil mass can be multiplied by 4.8 to determine the lateral force, but it is mathematically convenient to just multiply the soil weight by 0.15. SETTLEMENT from SEISMIC CONDITIONS Granular soils that are deposited in nature are generally loosely placed either by water or wind. Granular soils are sometimes loosely deposited by man in uncontrolled fills. Such loosely deposited soils have fairly large void spaces, sometimes called pore spaces. As more soils are deposited the loose soils will be pushed closer together until the soil grains contact each other, but not necessarily in the most compact condition. As the weight of overlying soils is increased, the contact force between soil grains increases, and the grains have more difficulty . sliding past each other to become more dense. That resistance of the soil grains to sliding into a more dense condition is the frictional resistance of the soils. That frictional resistance is one of the conditions that gives soils their strength to resist shear failures as heavy building loads are applied. The other condition that gives soils strength is cohesion, which is a sticky condition generally associated with clay and silt, and is nearly non-existent with coarse granular soils. Fine and medium granular soils are held together by dampness between the grains that bonds -.the grains like a Weak glue'. That bond between the grains can be lost by drying the soils, or by saturating them. That condition is well known by children playing in a sand box, where dry sand cannot be formed or molded, damp sand can be molded, and a molded sand form can be destroyed by pouring water over it. That water 'glue' is called capillary tension, which can only exist in granular soils when they are damp, and cannot exist in dry or saturated granular soils. That capillary tension is also what holds together clay soils and makes them sticky. The smaller the soil grains, the greater effect that a water bond has between the grains. Unless an extremely heavy load is applied to the deeper granular soils, the intergranular friction, and sometimes the capillary tension if the soils are damp, prevents the soil grains from sliding into a more dense condition, and they remain relatively loose: If the soils are suddenly jarred by an earthquake, the friction forces will be temporarily reduced, and the soil grains can be forced into a more compact condition when the weight of the upper soils is reapplied. As the seismic vibrations cause reduction and reapplication of the friction forces, the volume of the existing voids will be reduced, and the soils will settle an amount equal to that reduction in voids. That sometimes causes a large area to settle an. equal amount, and differential settlement can be minimal. Differential settlement of a structure can cause structural damage, and differential settlement outside the structure can cause external drainage and sewage lines to reverse flow, or can stress utility lines to the rupture point. L_J=KA ®U I I FIGURE 22 0 10 20 30 DEPTH (ft) — — — — 40 50 60 70 0 NOTES: LIQUEFACTION ASSUMED WATER TABLE I I I I I. I MAXIMUM GROUND ACCELERATION 0.1 g I 0.15g 0.2g 0:25g � LOOSE MEDIUM DENSE VERY DENSE 10 20 30 40 50 60 STANDARD PENETRATION RESISTANCE (blows/ft) THE VALUES SHOWN IN THE CHART ARE CONDITIONS FOR WHICH LIQUEFACTION IS UNLIKELY TO OCCUR (AFTER SEED and IDRISS) THE REQUIRED GROUND ACCELERATION TO CAUSE LIQUEFACTION INCREASES WITH DENSITY, AND ALSO WITH DEPTH FOR THE SAME SOIL DENSITY, BECAUSE THE WEIGHT OF THE UPPER SOIL INCREASES THE STRESS BETWEEN THE SOIL GRAINS WHICH THEN INCREASES THE RESISTANCE TO MOVEMENT OF THE SOIL GRAINS INTO A MORE DENSE CONDITION. SPIRO RESIDENCE LIQUEFACTION page 25 of 67 pages Another condition that occurs within loose granular soils during a seismic condition is called liquefaction. Liquefaction occurs two ways; by rising groundwater creating a 'quick' condition, and by trapped porewater reducing the strength of the soils. When granular soils that are below the groundwater level settle quickly during a seismic vibration, the groundwater that filled the void spaces of the loose granular soils is displaced and forced to rise. If the groundwater rises fast enough in more pervious soils, and can rise to the ground surface, then a 'quick' condition occurs. A quick condition is similar to the cause of quicksand, where the rising water moving past the soil grains reduces the frictional contact between the grains, and therefore causes a reduction of bearing capacity. The rising groundwater also saturates the previously damp granular soils and breaks the capillary tension bond. Therefore the soils have reduced load bearing capacity by losing frictional contact between the grains, and by losing the capillary tension bond. The 'quick' condition is also caused by increased pore water pressures that prevent the soils from maintaining frictional contact. When the sand grains have reduced friction caused by a vibration, and attempt to move into a smaller space, they are resisted by the porewater that hasnt been able to seep out of the pores as fast as the soils are settling. The soils are then supported by the porewater which acts like small hydraulic systems. Of course, water has no strength to resist shearing, therefore the porewater and reduced soil friction combination will fail under the imposed loads of the upper soils and the structure. Another type of failure caused by liquefaction occurs on slopes. A slope failure can occur within much deeper soils than a footing failure because the soils on the outer surface of the slope can fail, and then a chain reaction will occur as the friction forces deeper within the slope are reduced as each layer of the overlying soils slide away. Liquefaction can cause a failure on a slope even when the sand soils are covered by stronger or more cohesive soils that are not affected by the seismic vibrations Granular soils that have a greater frictional resistance to sliding into a more compact condition, either from being more dense, or that have a greater overlying load that both increases friction and also resists the upward vibration movement of the soils to release the frictional contact, will have a greater resistance to settling and/or liquefying from seismic vibrations. Figure. 22 is a graph that shows the probability of liquefaction based on the effect of seismic accelerations on saturated sands at various depths and with various densities. Assuming a density of 'medium dense', liquefaction could occur at the design acceleration of 0.15 x g in granular saturated soils above 35 feet from the ground surface. Since the potential line of failure, the top of the hard clay, and the groundwater level are all above critical depth of 35 feet, then liquefaction could occur at this site. !__9 I= (® A M U 1 1 w E5 `D A J My LW r i O Z O H V w M N w cc C� u. 0 N 11 w cc Q D N SPIRO RESIDENCE SITE STABILITY page 26 of 67 pages Figure 23 shows a section of the slope which includes the proposed house location and the property west of Meadowdale Road to the railroad. HEMPHILL assumes that the railroad is stable and supports the toe of the slope. There are ten points on the slope (A thru J) that define the shape of the slope to conduct slope stability calculations. An example of the calculations is shown in Figure 24 on the next page. The stability calculations are conducted at each point on the slope by dividing each slope into a series of slices, and calculating the safety factor against sliding for each slice. The stability of each series of slices is determined at various angles of slide plane, starting at 10 degrees and continuing at 2 degree intervals from each point on the slope where the slope changes direction. A seismic factor is included in the calculations based on the assumption that the lateral shaking will add lateral forces on each slice equivalent to 15% of its vertical weight, as previously explained. The 15% (0.15) is multiplied by the weight of the slice plus any external loads that are on the slice. There are no external loads included in this investigation. The house will not add loads to any slices because the piles will carry house loads to the soils below the critical potentially unstable soils. The estimated soil and slope parameters used to conduct the stability study are shown in Figure 25 on the next page. The shape of the slope was determined by the topographic plan shown in Figure 7, and by measurements conducted by HEMPHILL with inclinometer and range finder. The soil parameters are the worst estimated conditions, and are considered by HEMPHILL to be conservative. 3dO1S 10 301 Jp NOIlV1S 083Z !o 3N11 m Z `O r U J Q V J m` r J Ca G w N I.� ul LL w U J N 0 Ir w z w U' 0I z' O' F' Q F- in L 0 w U z 0 J F z O N cc O II x W U J V1 0 x a W 0 w cr- w Q m w a 0 J N w 0 IL w O O J � N L 0 0 w z O 0 I- 1= Q W J a W O (r W N w 0 H w z 301 INOHd 1HOGH ao II / 3011S JO dOl 10 NOUVA313 F- a. w 0 J o Co �0Q P IL WO Tr c J rn v A, O I--Q O 1.4 pC 14 4 W cl w i= F z z N v� O c x U LL W N F- N W j J J ca a �p N No ( H= p 0 U Z 0 m z w w w W z_U v_►.. 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Y d i •-O NN AP ^M J^NMdmO^ ^.-^;!A^ vv :^.n^^.-'Pm A.0.0.0 d 'a .o O dA Av+M.- n N V p i a O H r J W N O O O m d O O M J A O N VI m^ wf O O O O O d m N d O J m^ V1 P M A O Y1 O M O N O M A O d m y ^ W Y N �y •Y >• w M N N�}wt�{ m M N N A VC.p p,NN m.pM m d M NO A M m M 7r O 0 H v tY0 �f �^ dJ d^ ^NNN •N- — -^ ^^^^^^-O -PPPeO tOFA^•O .O .O d M MMMdwt MM N S Fz• W •'• ~d dd dd•O .O •O .O •O .O dd •O .O •Od•O .O .Odd•O .O .O d.O .O .O d•O d.O d•0 .0 .O d•O •Od dd dd F- N U yY- N• In J M N^ P C0 •0 N .f M N O R• C N ^ x. •• •t J d wt V wt M M M M M M M M M N N N N N N N N N^^^ ^^ .. L.J v x O O H W o N a z SPIRO RESIDENCE page 28 of 67 pages The worst safety factors occurred on a slope of 14 degrees located at point A, therefore only that set of calculations are shown in Figure 26. Figure 26 shows the calculations to determine the slope stability, and shows that the safety factors for the worst 10 foot slices under normal conditions (static) were 1.2 at point A with a 14 degree failure plane angle, and the worst safety factors for seismic conditions were 0.3. Although individual slices had low safety factors, the entire slope had a much higher average safety factor, because slices farther down the slope would require greater forces to begin sliding, and therefore will hold back the slices with lower safety factors. For seismic stability the overall slope does not show failure because of the stability of the lower slope, but the weaker slices might rotate out from the slope somewhere near the middle. The weakest portion of the slope is near the west edge of Meadowdale Road, and an actual slide might occur west of the road with the head scarp near the west edge of the road. The calculated line of worst slope passes through the known top of hard clay located in the borings. The true toe of a slope failure might curve into point C where the seepage zone exists. Although both the static and seismic safety factors exceed 1.0 at the site of the proposed house, they are not sufficient to assume that the site will always be stable. Slopes FG and HI show some minor instability because of the steepness of the slopes. Slope FG is not high enough nor in a potentially hazardous location, and slope HI will be supported and the stability will be improved. Slope HI is also composed of the more stable Double Bluff Drift. The stability of the site of the proposed house will be improved because the rear bench will be lowered, removing some of the driving loads, the rear steep slope will be supported by a soldier pile wall, and the piles for the house will help to hold the adjacent soils. An interceptor drain placed behind the soldier pile wall, and drainage for the house, will also improve the site stability. SITE PREPARATION CLEARING and STRIPPING In those areas where the structure, paving, or special landscaping will be placed, the ground surface should be cleared of any trees and shrubs, high grass and weeds, debris, and trash. The ground surface within the proposed structure, and under any. footings or paving, should be stripped of any sod, organic soils, and roots. NO ORGANIC MATERIALS CAPABLE OF DECOMPOSING SHOULD BE LEFT WITHIN THE PROPOSED STRUCTURE. Decomposing materials are the source of unacceptable odors, and can create methane gas, which can be explosive, and can also be harmful when inhaled. L_ L C) Z to J U — O a Cl) -a LL C 0 �R� V CC Z LL! O IL a w w v IL LL Q L ui cc C) Q Z w Y U CC. O ° m O. iu m D C) LL p 0 C) LLIJ J O O Cn O Q C W O a. U = F- Ld W 0 W O W ifF- W W -i LLJ > Q vLW= Q cam!) W CQt U F= p W 0 W W 0� J L.L 0 O > W U W U) 0 Z J L O OU W �m} O z `� O =QW = L u cc J p a W --� < W 0 O z �U)J .�. O U U¢ g W U Z Q c UO LL O Car Q Ir Q J OU LLJ F- D 0_jwU) J QCn Q WZ¢O O co Q0 cr W F- �� U tD OzF- -WLL Er C) ZOZ On- O 0ac0Q Q > waHWF- F- W Iz- ZO Q W 0 Q 0 oc Q Z C3 J �Q< C7 U)U) U)<Qpco m z F- F- CC -i 0 0 0 > 4 0 Q C) Z cn U oc _i U) W C) Z¢ �W WOpp HLLT cr p> < W= m 00 O O O W a: a: _ < LL O :DCO Mp U)U) w C`3r }>}w-w aC JZ �_ gog0 a W W Off" (.)EZ= CC_ °-Z W tW--z cr- �F7< a.� VY Vma-IL w �Q g° °M0a Q Q 06 U SPIRO RESIDENCE PROOF ROLLING PURPOSE OF PROOF -ROLLING page 29 of 67 pages Proof -rolling will densify the upper layer of soil, will compact any soil loosened by excavating operations, and will locate soft spots that should be excavated and replaced with structural fill. If the condition of the underlying soils is questionable, HEMPHILL might require that the soils be proof -rolled. DESCRIPTION OF PROOF -ROLLING Proof -rolling of a soil is accomplished by several passes of a heavy compactor. At those locations where the condition of the underlying soils is questionable, HEMPHILL might require that the soils be excavated and replaced with structural fill. PLACEMENT of WORKING SURFACE on SOFT SOILS Some of the existing soils at this site have a high silt and clay content. During wet periods, or before the soils dry sufficiently, construction activities on those soils will be difficult, if not impossible. The construction activities will cause any disturbed soils to become less dense, and to lose strength. If construction is scheduled during wet periods or while the soils are wet, and the soils become soft and difficult to support construction activities, then a working surface composed of coarse crushed rock can be forced into the soft soils that will then support the construction equipment, will protect the underlying soils from disturbance, and might be a satisfactory base for the structure and pavement. The site should be stripped of the upper vegetation and organic soils. Poorly graded crushed rock should be placed over the existing soft site soils and then forced into the softer soils by a heavy vibrating compactor, as shown in Figure 27. This procedure requires close supervision to ensure that the crushed rock is forced to the more competent layers below, and rises above the soft and wet soils, and that the soft soils do not support the rock, but fill the void spaces between the crushed rock. GENERAL SITE EXCAVATING REMOVAL of UNACCEPTABLE SOILS Any existing fill and/or any loose or soft soils that are considered unacceptable by HEMPHILL should be removed from the ground surface with as little disturbance as possible to the acceptable soils that remain in place. Those unacceptable soils should either be removed from the site, or used' for landscaping, provided that the placement of the soils does not create any instability. HE HILL Cl) J_ a cl w Q Q U x w co N w C) LL r 0 SPIRO RESIDENCE page 30 of 67 pages EXCAVATING to SITE GRADE The proposed excavating will be conducted to lower the bench along the east side of the site. Lowering the bench will allow easier access to the garage. A soldier pile wall will be installed to support the upper slope prior to the excavating. Figure 28 shows the soils to be excavated, and the soldier pile wall. MAXIMUM EXCAVATED SLOPES HEMPHILL recommends that the final grade of any slopes that are excavated and not protected should not exceed a slope of 1 vertical to 2 horizontal for easy maintenance, better erosion control, and stability. If steeper slopes are desired, then the maximum steepness of the slope will depend on the type of soils, their physical properties, groundwater conditions, the proposed heigot of the slope, the proximity of the slope to adjacent structures, and landscaping and maintenance requirements. The existing Double Bluff Drift can stand nearly vertical for many feet, but will gradually lose its surface due to weathering from wetting and drying, freezing and thawing, minor groundwater seepage, surface erosion from stormwater runoff, and root action. The maximum slope that the Double Bluff Drift could stand permanently is approximately 1 vertical to 1.5 horizontal. EXCAVATING for STRUCTURE Portions of the bench will be excavated from under the garage and house, as shown in Figure 28, but any other excavations will be for placement of crawl space, piles, and grade beams. Except for the east half of the garage, the rest of the structure will be over crawl space. The interior portion of the structure, and the working space for the construction of forms for grade beams, will be excavated approximately 2 feet below the final ground surface. HEMPHILL recommends that the excavations for the garage and the house be sloped to the northwest a total of 6 inches or V/10' to allow any interceptor drains, and any water in the crawl space or under the garage, to flow to the northwest corner, and to prevent the accumulation of groundwater in the crawl space or under the garage slab. ALLOWABLE SLOPES for SIDES of EXCAVATIONS Deep excavations are not anticipated at this site. If unexpected excavations should be required, then any excavations less than 4 feet deep can have the sides sloped as steeply as they can stand. Where workers will be active adjacent to the sides of excavations that are deeper than 4 feet, the sides of the excavations should be sloped no steeper than 1 horizontal to 2 vertical for the protection of the workers. Some soils might require slopes less steep. SPIRO RESIDENCE page 31 of 67 pages Safe slopes within the excavations should be made the responsibility of the contractor, and should be accomplished in compliance with current local, state, and federal codes and practices. Such codes would include the Occupational Safety and Health Act of 1970 (OSHA) and the 'Safety Standards for Construction Work' of the State of Washington, Department of Labor and Industries, Division of Safety. GENERAL SITE FILLING The only anticipated fill will be placed to construct the driveway, and possibly for some landscaping. The driveway must be constructed of structuralfill to resist settling and to be capable of supporting vehicles and the back porch. The fill must also resist frost. If the depth to subgrade and/or allowable bearing soils is greater than anticipated, the contractor can choose to over -excavate to soils approved by HEMPHILL, and then to backfill to the required grades with structural fill approved by HEMPHILL. With the approval of HEMPHILL, the contractor can choose the structural fill from among those soils available from commercial suppliers, from offsite borrow pits, or from any existing site soils that are determined by HEMPHILL to be satisfactory for structural fill. The excavated Double Bluff Drift might be an excellent structural fill. DESCRIPTION of RECOMMENDED STRUCTURAL FILL Structural fill is defined as any soil that can be properly compacted to achieve any or all of the physical properties that are necessary to support foundations, to diminish building and paving loads to softer soils below, to undergo acceptable settlement, to resist attracting capillary water to the underside of the floors, footings, and paving, and to be workable when wet. Many combinations of grain sizes would be satisfactory as a structural fill soil, depending on the water content of the soil, and on weather conditions. During wet weather or any wet conditions, soils with greater than 5% passing the no. 50 sieve will be difficult, if not impossible, to compact. With the approval of HEMPHILL, the contractor can choose the structural fill from among those soils available from commercial suppliers, from offsite borrow pits, or from any existing site soils that are determined by HEMPHILL to be satisfactory for structural fill. The properties of most acceptable soils that are properly prepared as structural fill are well documented, and can be easily estimated by a geotechnical engineer. SPIRO RESIDENCE page 32 of 67 pages PREPARATION of EXISTING GROUND SURFACE for FILL Prior to placement of structural fill on the existing ground surface, high grass and weeds, tree roots, loose piles of soils, debris, any unacceptable fill, any organic soils, and any loose or soft soils considered unacceptable by HEMPHILL should be removed from the ground surface with as little disturbance as possible to the undisturbed soils that remain in place. When structural fill will be placed on an existing slope of finer grained soils, the slope should. be excavated so that the structural fill is placed on a nearly level surface to prevent the fill from sliding down the slope. The slope can be excavated to a series of steps approved by HEMPHILL PLACEMENT of STRUCTURAL FILL on SOFT SOILS During wet weather, if a working surface has been placed, the structural fill can be placed directly on the working surface in 8 inch layers, and compacted to the required density. If a working surface has not been placed, and the existing site soils are soft and cannot be removed without disturbing some of the underlying soils, then the first layer of structural fill can be placed with the maximum thickness that will allow the compacting equipment to work without causing rutting. If more than 12 inches of fill is needed to prevent rutting, then lighter compaction equipment should be used. The first layers should be compacted with several passes of a heavy vibratory compactor. Each additional lift should be 8 inches or less and compacted to the required density. CONTROL of COMPACTION of STRUCTURAL FILL LABORATORY TESTING The proper compaction of a structural fill is generally related to the densities achieved by a Modified Proctor Test. A Modified Proctor Test (ASTM D-1557) is conducted on each different soil type to be used for filling to determine the required minimum density of the structural fill to achieve the desired properties. The Modred Proctor Test also determines the optimum water content that will best achieve that density. A Modified Proctor Test is achieved in a soils laboratory by conducting a series of compaction tests, each with a different water content. Eachtest is conducted by compacting a specific volume of the soil with precise compaction procedures with a controlled or measured water content. A curve is plotted comparing the density achieved for each water content of the soils during the test. SPIRO RESIDENCE page 33 of 67 pages The highest point on the curve shows the water content at which the density of the soils is the greatest. The maximum density on the curve is called 100% of the Modified Proctor maximum density, and the water content that achieved that density is the optimum water content at which the soil compacts most easily. At that density the soils are considered to be capable of supporting their maximum loads with minimum compressing, or settlement. The results of Modified Proctor tests are different with different soils. The geotechnical engineer must be capable of recognizing soils that will have different properties when compacted, or he should conduct periodic classification tests to identify different soils. HEMPHILL should determine when a Proctor Test is required on a different soil type. PLACEMENT of STRUCTURAL FILL Sometimes the desired properties of a structural fill can be less than those achieved at 100% of the Modified Proctor, and the geotechnical engineer can specify a lower value, such as 90% or 95% of the maximum density achieved in the Modified Proctor test. The properties of the structural fill can either be determined by testing in the laboratory, or by comparing with known properties of a similar soil that have been determined by past testing by the geotechnical engineer, or are common values that have been published in engineering journals. The procedures to achieve the proper density of a compacted structural fill are dependent on the size and type of compacting equipment, the number of passes to be made over the soils with the compactor, the thickness of the layer to be compacted, and some properties of the soils, including water content. The density of a soil can sometimes be increased by increasing or reducing the water content of the soil, and using the same compactive effort. Water reduces the friction between soil grains and helps the soils to slide into a more compact condition with the same compactive effort. The value of water to decrease friction, and therefore increase compaction, decreases as the soil grains become larger. Water has very little effect on the compaction of coarse sand and gravel. Dry soils can seldom be compacted to the maximum density determined in the laboratory. A higher compactive effort could achieve the same density with less water, with some limitations. As the water is decreased, the friction between the soil grains increases, and as heavier compactive loads are applied the friction between the soil grains increases to resist the compactive load from forcing the .grains into a more compact condition, therefore at some point of lower water content, the heavier compactive efforts increase the . resistance to compaction, and nothing is accomplished. If the compactor vibrates, then the friction forces between the soils are temporarily reduced as the load of the compactor is released during the upward motion of the vibration cycle. The soils can then move into a more compact condition during the release, or are forced together as the load is reapplied during the downward motion of the compactor. iiiiiiiiiiiiiiiiij SPIRO RESIDENCE page 34 of 67 pages More water reduces more friction between the soil grains, but as the water fills the pore spaces between the grains of the loose soils, it takes up some of the space that the soils need to become more compact. With coarse grained soils, such as sand and gravel, the water can be forced out of the pore spaces very quickly as the soils are being compacted, but with fine grained soils, such as clay, sift, and fine sand, the water cannot squeeze out fast enough, and it fills the pore space before the soil has compacted to the desired density. The trapped water then becomes a hydraulic piston that supports the loads of the compactor and resists further compaction. That condition is not always obvious with clay and some silty soils, and the only way to know that compaction has not been achieved is to conduct density tests. With some coarse silts and very fine sands, the water is forced into adjacent pore spaces under high pressure as the compactor loads are applied, but when the compactor releases the load as it moves on, the high pressure water is forced back into the just compacted soils, and the soils rise. The observer will see the soils compact and then rise again, an action called pumping. That indicates that the soils are not being compacted because they are too wet. The ability to increase density with compactive effort is limited by the strength of the soils to resist bearing failure. If the compactor is too heavy, or imparts too great an energy, then the soils adjacent to the compactor will shear up around the sides of the compactor, and then the compactor will compact the soils under it, but will loosen the soils adjacent to it. Density tests can be conducted in the field to determine that -the required percent of the. density determined by the Modified Proctor test has been achieved. The locations and quantity of tests required to control the compaction are determined by the geotechnical engineer in accordance with the number of different soils and the soil types, the sizes and types of compacting equipment, the extent of the field supervision, and the results of laboratory and field density tests. Field density tests are conducted by obtaining samples of the field compacted soils, measuring the volume of the sample by measuring the hole from which the sample was obtained, and then weighing the sample in its natural condition, and again after drying, to determine the dry unit weight and the water content. Field densities and water contents 'can also be determined by nuclear devices, but ,that equipment is only feasible on very large projects. Generally, poorly compacted soils are the result of poor workmanship, or fine grained soils being too wet, or coarse grain soils being too dry. To achieve the desired properties of a properly prepared structural fill requires the control and guidance of an expert and/or a testing laboratory.' If ft is determined that the laboratory and field testing required to control the compaction of the soils is not warranted at this site, then HEMPHILL should observe and approve the compaction procedures, and should verify that the soils have achieved the approximate desired. properties. SPIRO RESIDENCE page 35 of 67 pages DENSITY REQUIREMENTS of STRUCTURAL FILL Structural fill that will be located beneath the proposed deck footings, the back porch; under paving, or areas where settlement would be undesirable, should be compacted to a density equal to or greater than 95% of the Modified Proctor maximum density (ASTM D-1557) for that particular soil. Structural fill to be used for temporary bearing under grade beams should be compacted to a density equal to or greater than 85% of the Modified Proctor maximum density (ASTM D-1557). Structural fill that will be used to backfill excavations that will support steps, walks, or driveway paving where settlement would be undesirable, should be compacted to a minimum density equal to or greater than 95% of the Modified Proctor maximum density (ASTM D-1557). Structural fill to raise the site grade but not supporting paving or portions of the structure should -be compacted to a density equal to or greater than 90% of the Modified Proctor maximum density (ASTM D-1557). Structural fill that will be for landscaping, and that will not support loads, can be compacted to a density equal to or greater than 85% of the Modified Proctor maximum density to minimize settlement and shifting, and to be fairly stable on slopes less than 1 vertical to 2 horizontal. COMPACTION of BACKFILL ADJACENT to STRUCTURE The only portion of the structure that will have significant backfill placed against it is the soldier pile wall at the northeast corner of the house. Imported soils might be required adjacent to the structure where drainage is required. The requirements for drainage materials will be described later in this report. Compaction adjacent to the structure should not be conducted until the concrete has cured to an acceptable strength in accordance with the recommendations of the structural engineer. Compaction adjacent to the structure should be accomplished with light hand operated equipment within a distance of the structure equal to the depth of the fill, so that no excessive lateral pressures are applied to the structure. HEAVY EXCAVATING EQUIPMENT SHOULD NEVER BE USED TO PLACE OR TO COMPACT STRUCTURAL FILL ADJACENT TO THE STRUCTURE. HEM P1-11 LL V Z i-- Q U X W W O L O w W Q W O cc IL cn W m W C 0 W U) cc zz=) a0 U W Q m Z IL W M a �R V Z Z ~ H O Q 0 L U W W W > O O aU L Cl)"- CC m D (13 Ca W Z cc 0 cc a W cc a t-"�J JJ Am o uC 'aW tC >Om- mO C Imm 0.> '° aOx0 m mx °CE =a ma— co Lm 0 ma ° �•Mmy"o� m oW- 'a )0wm 0C om a om ._ 015 -B�mO .T � dfl a do C 0� 7 01 p1.0 0. N� .O Nt Nr m i 01 i «•'U �r N� 0 uQ C3 mm mo N iu �°'L rL �aEm N uT OL - m"a 3Q��ro E •v - ° �� `o`� m 3 mztiv Em-tt r:', m , dmc ° aEQm 02 ` z CO .0>ID C icto ° ME• D oa mm IN �_ E m -0° c im-- m22000 m N all c J m'O II —j > ma 0,0 oQc m cm, m C.m. '0 m= Cxf m m� «E m omg�E C rZN]Oy0d- oO rn 0 No �o'o T RR0 . 90CcmCL CuO 7E:°GN 9«. y m Im m mY C O E mm Cm m`0 -C O_tc m EomE._ oa'�m Vm �N t A=Om� m0-6 Cm C aCL CD m o °c=•°3� a m m m A m« « `° m v ti� Im O a -° xto m01� a mmE° mE ma°a _-sec mm l0 m= m m 0 wN O �NE m e o cE.000 pm O. m O- ° 05 co a om, a omNCm�vcyo° oLmi°a°oi. -m mt•- tV Ja 'O.0 O) SN .003 C0 � mC no EoWa aSro =x-L�u =:�aC1u Y•`Q �io`m mumWE o xa 2� CL m>.oDox mO Nat Nmm 0 m N G 'U :S m a O 'O m ODJ G A mO m aaa J acco N_ crn;c °«a °=mmS .a jN2 oo oo. �2 °emu W Nc= oW CL o.x tom m« N ca 00 .0m NOd a �>m0 .C" Dm UO�0 m 7 ww 0CN-30mmo _C c O.0 E > ° mm aEo •0•° -N oco 'a E c ° oaciuri �o m�y'�°' C O m ° WO 0Ia 5—M= C m 7° ° "' OVT NA m E m m C Ot m cNm-, o. N au '0 cvoc� > t.. m -5 -C E M T 'a OmO ma mmm ami 0 cNm> O. `m�° n 2, m «; °CL D;�°x m' �m C �m o« v My �a�o mom° i.mm r� mOmC - C mo mm m Z0 O=V O1 O«t md0 N 000$'O mC0«NLC; m CO m jN cc, Mm m 06 02 U �m3u0, cm °o $ O o AJJC" uC O i m0 m-•M. �m 0—ca. ao o rn— o NCmL 00 c N E.o 0002 O Nm•Vl O. mQ $.d 0 A m my«" M 3o d« wNmmW o°m= '0o. 0E o0E.: -0 m°Na m� s -c «Cxy o� o��o ov C m - a c a o m ; •• m E c ; O m� N•° y m•KD C m mo>` oo m �f0 ;.2cl- $L E m 0 ao «� S o 0 =t -= u v 000.m >U O.N C�Na 0.0 moS1� CCL m m'`mo°X(A W w� mWoia �= rammm = H v co .o SPIRO RESIDENCE page 36 of 67 pages SOIL DESIGN PARAMETERS for TEMPORARY FOUNDATIONS The foundations for the main structure will be cast -in -place reinforced concrete piles supported by permanently stable soils, but grade beams, the back porch, the spiral stair, and the deck footings will be placed on the upper potentially unstable soils that are capable of temporary support until a slide occurs. The conditions that will cause the instability might never happen in the lifetime of the proposed house, or they might only happen on the lower slope. The temporary bearing soils will be prepared as would any permanent soils. PREPARATION of EXISTING SITE SOILS for TEMPORARY FOUNDATIONS 1. All organic soils, roots, and grass or shrubs should be removed from beneath any locations for deck footings or grade beams. 2. If loose or soft soils, or soils other than the approved soils are encountered at the proposed locations of the grade beams and deck footings, then the excavations should continue to competent soils approved by HEMPHILL, and the footings placed on the competent soils. 3. Soils at the bottom of footing excavations should be probed by HEMPHILL.to verify the bearing capacity, and to locate any soft spots. 4. Any soils loosened by the excavating process, or softened by wet conditions, should be hand excavated. Loose and soft soils should not be hand compacted. Irregularities at the bottom of excavations should not be filled. 5. At the contractor's option, and with HEMPHILL's approval, any over -excavations for footings may be backfilled with either lean concrete or structural fill. 6. Unless approved otherwise by HEMPHILL, any footings that are over -excavated, and that will be backfilled with structural fill, should be excavated beyond the edges of the proposed footing a minimum distance of 1 foot for each 2 feet of over -excavation, as shown in Figure 29. BEARING CAPACITY of SOILS The upper very fine sandy sift soils and loose gravely sand soils that were recovered during the Standard Penetration Test, and that might be fill, might be capable of supporting loads of 2000 psf after proper preparation, but, those soils might not be consistent over the site. The underlying medium dense silty fine sands are also capable of supporting loads of 2000 psf after proper preparation, but those soils might not be consistent over the site. HE M P HILL SPIRO RESIDENCE page 37 of 67 pages The temporary allowable bearing capacity of the undisturbed soils should not be increased for temporary loadings from earthquake and wind forces, therefore a maximum allowable design bearing capacity would be 1500 psf, and with a total of 2000 psf allowable for dead, live, and temporary wind and seismic forces. Those values are presumptive and should be verified at the time of construction. SETTLEMENT ESTIMATIONS Some settlement can occur resulting from the densification of the upper 17 feet of soils from seismic vibrations. HEMPHILL estimates that the soils could density an additional 5%, which would cause approximately 9 inches of settlement. Seismic vibrations could also cause liquefaction, and the resulting settlement would be the result of sliding. Liquefaction might not occur if the proposed drainage system is successful in intercepting the source of groundwater under the site. The amount of settlement from sliding cannot be estimated. There will be no building loads to cause settlement except for the temporary loads from the grade beams until they can support their own weight. The rockery, the deck footings and spiral stair, and the fill for the driveway might cause some settlement. Any settlement can add drag loads to the piles that will be discussed in the section on piles. SETTLEMENT of GRADE BEAMS Since the grade beams will not be loaded until the concrete has cured sufficiently to support the building loads (approximately 30 days), then the only loads on the soils from grade beams will be the initial wet weight of the concrete for the grade beams, which will not exceed 600 psf. If the soils are properly prepared, then that bearing should not cause any significant settlement. Most of the settlement from the weight of the grade beams will occur quickly while the concrete is still wet, and any additional settlement will be minimal. As the flexibility of the concrete decreases during curing, the strength will increase to begin supporting its own loads. Additional flexing from building loads is anticipated by the design and no further support from the soils is needed. In fact, the grade beams are designed for the soils to slide out from under the grade beams, therefore any additional settlement for seismic or other reasons is of no consequence after the third day of curing. SETTLEMENT of GARAGE SLAB The only portion of the main structure that could be affected by settlement would be the structural garage slab during curing. The east half of the garage slab will be placed on an excavated surface approximately 10 feet below the existing ground surface on the east bench. The loads to be exerted by the garage slab during curing will be less than 75 psf. After approximately 7 days the garage floor will be capable of supporting itself and any settlement will have no affect on the slab. Because of the strength of the Double Bluff Drift soils, the removal of 10 feet of soil, and the light loads, settlement during curing of the slab is not anticipated. HEM PHILL FI_G.URE 30. W N 0 cn a Z H 0 0, LL Z 7 log 5 4 3 2 BEARING and SETTLEMENT vs FOOTING SIZE and DEPTH for MEDIUM DENSE SAND 2 3 4 5 6 DEPTH BELOW GROUND SURFACE (feet) SPIRO RESIDENCE page 38 of 67 pages SETTLEMENT of BACK PORCH The back porch will be placed over structural fill compacted to 95% of the Modified Proctor maximum density (ASTM D-1557), therefore minimal settlement will occur, unless there is poor workmanship. Because the structural fill will be supported by a retaining wall that will be into or near stable soils, then HEMPHILL anticipates that a slide will not affect the porch. If, at the time of construction, HEMPHILL determines that a slide could move from under the retaining wall, and that the porch could be undercut, then HEMPHILL will recommend that the porch not be attached to the house, and that the roof overhang be cantilevered and not supported by columns supported by the porch. SETTLEMENT of DECK & STAIRS Deck and spiral stair footings will be placed on soils capable of supporting loads of 1500 psf with minimal settlement until the soils become unstable. The undisturbed soils and any structural fill will probably settle a similar amount for similar footing sizes and loadings. Figure 30 shows settlement vs bearing vs footing size vs depth of footing. Although off the chart, a loading of 1500 psf placed 1.5 feet below the ground surface with a minimum 18 inch square footing will settle less than 1/4 inch. Deck footings will probably never be loaded to that capacity. If the deck is partially or completely supported by spread footings to save the cost of a piling foundation system, the amount of settlement to be anticipated cannot be determined because the settlement can range from minimal for compression of the soils while they are stable, to significant for seismic settlement, to extensive for a slide settlement. The deck should be designed for the worst case, which is a -complete failure of the spread footing support system. The decks can be designed by any of 4 methods: 1. As a cantilever system supported by the main structure with no bearing on the soils. Research by HEMPHILL has revealed that cantilevered beams tend to create opposing deflection compared to adjacent non cantilevered beams, and can cause deflection in the outer wall and windows, and can cause distortion of any windows or doors that are parallel to the direction of the cantilevered beams. HEMPHILL has also observed that the distortions can occur over a period of time as the stresses cause creep in the wood structural members. 2. As a cantilever system that can support the dead and live loads, or just the dead loads, and temporary post and footing support to eliminate the deflection. This system might reduce the distortion inside the structure, but the supporting posts and footings can move with any slide or settlement. The posts and footings can be replaced after such movement, or if the settlement is minor, .shims can be added between the footing and the post, or between the post and the upper deck structure. The post can be hinged to the upper structure, or can be connected rigidly to the upper structure and just placed on the footing, allowing the footing to move from under the post. HEMPHILL FIGURE 31 _ _ LOCATIONS of DECK FOOTINGS DECK & SPIRAL STAIR 'FOOTIIVGS SPIRO RESIDENCE page 39 of 67 pages 3. As a hinge system connecting at the main structure, with a system of posts and footings. This system requires the post and footing to support half the deck dead and live loads, and if the footings move with settlement or slide, they can be replaced. The deck must be attached to the main structure by a hinge system so that any deflection will not distort the main structure, and the deck can be jacked back into place. 4. As a separate structure not attached to the main structure, supported by spread footings and posts. This system can move with settlement or sliding and then can be jacked back into place after any movement. The deck must be light and rigid to be manageable but not extensively damaged. The disadvantage of this system is that there could be differential settlement or separation at the door to the deck. The spiral stair can be hinged where it connects with the deck, or it can be a free system not connected to the deck or main structure, otherwise the deck and stairs might damage each other during a slide failure. DESIGN and PLACEMENT of SPREAD FOOTINGS for DECK & STAIRS Figure 31 shows a plan of the grade beams, and the temporary spread footings for the deck and the spiral stairs. The temporary spread footings will be designed for bearing on the existing soils without concern for future settlement from seismic or stability failures. OVER -EXCAVATIONS to BEARING SOILS Based on the allowable 1500 psf bearing capacity of the existing soils described as sifts and fine sands, if the depth to allowable bearing soils is greater than anticipated, the contractor can choose to over -excavate to bearing soils approved by HEMPHILL, and then to backfill with structural fill or lean concrete to the desired grades of the bottoms of the footings. Any over -excavations of footings required to encounter the allowable bearing soils which will then be backfilled with structural fill, should be excavated 1 foot wider than the footing for each 2 feet of over -excavation, as shown in Figure 29 on page 36. If allowable bearing soils are not encountered within a reasonable depth, then HEMPHILL can determine the bearing capacity of the encountered soils, and can determine the required thickness of structural fill under the footing to dissipate the footing pressure to the allowable bearing capacity of those soils, provided that the compressibility of those soils is acceptable. FIGURE 32 LOCATIONS of PILES NOTES: 1. PILES are NUMBERED for REFERENCE DURING CONSTRUCTION. 2. SOLDIER PILES in RED (16, 17, 11, 7, 8) are 24' DIAMETER 3000 psi CONCRETE with W-12-58 STEEL BEAMS PLACED MINIMUM 251 BELOW BOTTOM of WALL 3. INDIVIDUAL PILES UNDER HOUSE SHOWN in BLACK ARE 185 DIAMETER 3000 psi CONCRETE with W-10-33 STEEL BEAMS PLACED MINIMUM 301 BELOW BOTTOM of GRADE BEAMS. 4) 4. SOLDIER PILES at REAR of HOUSE are 160 DIAMETER 3000 psi CONCRETE with W-8-28 STEEL BEAMS PLACED MINIMUM of 7.5' & MAXIMUM ill BELOW EXCAVATED SURFACE. SPACINGS to be DETERMINED AFTER EXCAVATIONS for BENCH have been COMPLETED. 1�y 12 17 18. II II 19 20 22- 25 26 27 SCALE I"= APPROXIMATELY 10 7Q 3 6 10 0 14 21 .0 23 28 SPIRO RESIDENCE page 40 of 67 pages MINIMUM WIDTH of FOOTINGS The footings can be sized based on the dead and live loads, including wind and seismic, assuming 2000 psf bearing capacity. MINIMUM DEPTH of FOOTINGS MINIMUM DEPTH for BEARING Footings can be placed directly on the existing soils, or on structural fill, that have been approved for bearing by HEMPHILL. MINIMUM DEPTH for FROST PROTECTION Footings should be placed a minimum of 18 inches below the final ground surface to protect against uplift due to frost expansion, or loss of bearing capacity due to softening from thawing conditions. DESIGN of GRADE BEAMS Grade beams to be adjacent to unheated areas should be placed a minimum of 18 inches below the final ground surface to protect against uplift due to frost expansion, unless the grade beams are designed to resist uplift. At that depth below the existing ground surface HEMPHILL anticipates that the soils can offer the necessary temporary support, which should be verified at the time that the soils are exposed during the excavating process. PILE FOUNDATIONS and RETAINING SYSTEMS Figure 32 shows the locations of all the piles for the project. The piles are numbered for convenient reference during design and construction. There are 3 kinds of piles for the project: INDIVIDUAL PILES - The house will be supported by individual piles, each designed to support itself. against the lateral drag forces of sliding soils, and to support the vertical loads of the house. 2. RETAINING WALL PILES - The partial octagonal shape shown in red at the northeast corner of the house has exterior reinforced concrete retaining walls that will support the driveway backfill soils. Those walls will be supported by cast in place concrete piles with steel beams extended to the top of the walls. The walls will be supported between the beams, similar to soldier piles. 3. SOLDIER WALL PILES - The rear slope will be protected and supported by a soldier pile wall that will be placed prior to excavating the rear bench. FA SPIRO RESIDENCE page 41 of 67 pages The piles that support the house are designed based on an allowable deflection of 1 inch rather than a safety against failure. Of course, bending, shear, and vertical support are checked for safety. The chosen piles are the smallest piles that are safe from failure and still within the allowable deflection and stresses. CONSTRUCTION PROCEDURES If the soils are capable of standing open after drilling, then the open hole method of placing piles can be used. The hole can be drilled with either a continuous flight auger, or with a short auger that drills a short distance and then withdraws to spin off the soil. After the hole is drilled and the auger has been withdrawn, the required depth of the hole should be verified by HEMPHILL The steel beam can then be inserted into the hole with the flanges placed parallel with the slope, except for the retaining wall piles, which will be explained later. The hole is then filled with either concrete or grout. If water or muddy soils collect at the bottom of the hole, then the concrete or grout should be pumped into the hole by placing the hose at the bottom of the hole and then withdrawing the hose as the concrete or grout forces the water and mud up the hole. The contractor or a representative should be available with a level and rod to control the level of the concrete, and to place the reinforcing rods that will tie the pile to the grade beam. The advantages of placing reinforced concrete cast -in -place piles by the open hole method are that the soils can be verified, that steel can be more easily centered in the hole, and that the volume of the concrete is more easily controlled with less waste and cleanup. If some of the borings for piles would collapse if the holes are left open, then HEMPHILL recommends that cast -in -place piles be placed by boring the hole with a continuous flight auger. A continuous flight auger drills a continuous hole without withdrawing from the hole, therefore the auger temporarily supports the hole from collapsing. The continuous flight auger has a hole in the center through which grout is pumped as the auger is withdrawn. The grout, which is more dense than the surrounding soils, then supports the hole. Grout is composed of cement, sand, and water, which is more easily pumped without clogging, and which allows steel to be more easily placed. The grout must be pumped under continuous pressure, and the auger must be withdrawn at the correct speed so that the grout completely fills the void left by the withdrawing auger before the surrounding soil squeezes into the hole. If soil squeezes partially into the hole, it will create a narrow undersized section of pile. If soil completely fills a section of the hole, then the pile will not be continuous, and the entire pile will be no stronger than the reduced section, and the steel could be exposed to eventual corrosion. The steel beam can then be placed in the grout filled hole after the auger has been completely withdrawn. If the hole is longer than the steel beam, then the beam will require temporary support until the grout has partially cured. FIGURE 33 DESCRIPTIONS of RESISTING SOILS G R A N U L A R S O I L S -------------------------------------------- RELATIVE SOIL STANDARD f DENSITY CONSISTENCY PENETRATION (pci M (blows/ft) /ft) --------------------------- 0 ------------------- 0 0 VERY 10 LOOSE ------------------- 4 5.6 20 LOOSE 30 ------------------- 10 12.7 40 MEDIUM 50 DENSE 60 ------------------- 30 37.0 70 DENSE 80 ------------------- 50 54.5 90 VERY DENSE 100------------------- 70 69.4 C O H E S I V E S O I L S -------------------------------------------- UNCONF'D SOIL STANDARD f COMPR'SN CONSISTENCY PENETRATION (pci (psf) (blows/ft) /ft) ---------------------------- --- 0------------------- 0 0 VERY SOFT 500------------------- 2 2.3 SOFT 1000------------------- 4 5.6 1500 MEDIUM STIFF 2000------------------- 8 12.7 STIFF 4000------------------- 15 VERY STIFF 8000------------------- 30 HARD 12,000------------------- 60 N O T E S * = LATERAL SOIL MODULUS is CONSTANT f = RATE of CHANGE of SOIL MODULUS with SOIL DEPTH = 50.2 pci/ft * SPIRO RESIDENCE page 42 of 67 pages A disadvantage of drilling with a continuous flight auger is that the soils cannot be observed to verify that the required bearing soils have been encountered. If the bearing soils are much harder than the overlying soils, then the location of the top of the bearing soils will be obvious by the increased difficulty of drilling. If the bearing soils are not significantly harder, or if the soils are uncemented sands, then the top of the bearing soils might not be obvious. Either previous investigations will have been required to locate the top of the bearing soils, or the piles must be designed to be long enough to assure that the piles are embedded the minimum regUired depth into the hard clay for both bearing and friction. STRUCTURAL DESIGN of PILES The piles were designed using steel beams because of the need to retain soils between the piles (soldier piles), and because most contractors opt to use steel beams because of the ease of placement and reduced labor costs. The ability of the piles to resist lateral forces is dependent on the steel beams because the tension side of the concrete is of no value, and because the bonding between the concrete and the steel beam to transfer bending in questionable. Therefore the lateral forces on the pile are determined by the diameter of the concrete, but the strength of the pile is determined by the steel beam. SOIL DESIGN PARAMETERS for PILES LATERAL RESISTANCE All the piles were designed based on the lower portions of the piles being placed into the hard Whidbey Clay the necessary distance to resist lateral deflection of the piles, which also resists lateral failure of the piles. The resistance to deflection for various soils is shown under the T column in Figure 33 which shows the stress/strain rate for granular and cohesive soils with various consistencies. Although the Whidbey Clay is a hard clay, because of the over consolidation HEMPHILL assumed those soils to act more like a dense to very dense granular soil, therefore all the piles are based on f = 50 pci/ft, which is the rate at which the stress/strain increases. At the top of the hard clay 50 psi causes a strain of 1 inch, but at 1 foot lower it requires 100 psi to strain 1 inch, and at 2 feet it takes 150 psi to strain 1 inch, and so on. VERTICAL RESISTANCE The stable Whidbey Clay can offer vertical support on the piles at conservative values of of 6000 psf bearing and 1000 psf friction, therefore an 18 inch pile with 15 feet of embedment into the hard clay can support loads in excess of 80,000 pounds. If a seismic condition causes some settlement of the upper 15 feet of loose soils, then the drag would only be approximately 8000 pounds, assuming an EFP of 40 pcf acting over the area of the pile surface, and with a friction factor of 0.4, all conservative values. i u L 0 in w U' z ~ N LL 0 (t w D cr N O 0 z a 0 O Hld3a cc 0 `0CL = F O 0 x w - \max a 0 M w O LL - x Z = F w W CL W W 0 a x LL EL LL cc m W_ (n u w II 0 C LL J N ld I x w x F = a Q w M 0 e c W x to ccOx O ti z u. (7 _ + + x O Z ZL = a LL o ,_ X U It X U)J U) Cl)x LL w N y J_ W p w 11 11 Z II IG W (n O Z O W W W W O U W Z (5 N Q Z J s Z g N ala I. U z U O cc C J 0 J W O W Vr 0 J -N ZZw a ch C7 O ZZ0 0 x �aOM w ULLU CC JUs LL J Uw w OC cc a- v c cc oC O x LL U)i ¢ w= 0 U- w w LL 11 J w z C a co x V O z Z W > w W N Z M p W Z W 2 cn J J cr x 0 Wha- II z N Z O W 11 I p U O O LL M LL II a II II it I) II n II p a x cc 11 LL LLJ_ _ SPIRO RESIDENCE page 43 of 67 pages LATERAL DRIVING FORCES on PILES The driving soil design parameters for the individual piles are based on a silty sandy soil that has a fairly high strength at the time of failure assuming that the soils are worst at the slide plane and stronger above. The stronger the soils above the slide plane the greater the force exerted on the pile. To presume the soils below the slide plane to be weaker, and the soils above the slide plane to be stronger, presents a more conservative design. The individual piles, so named because each pile is independent of other piles, are designed based on the lateral forces of the potential sliding soils sliding past the piles and dragging on the piles and the cone of soil that becomes trapped behind them, as shown in Figure 34. The angle of the cone is similar to the angle of failure under a footing in a bearing failure. Figure 34 shows the pile and the cone, the labels for the forces and dimensions, and the calculations for the lateral force (Ft). The piles are designed based on the sliding soil dragging on the length X + Y on each side of the pile. The friction factor for the sliding soils on the concrete and the sliding soil on the cone is considered to be similar, since if soil sticks to the concrete, then the sliding will occur between that soil and the next layer of soil, otherwise if the friction between the concrete and the soil is less than between the soil layers, then the calculations will be conservative. The shearing force (Fs) is the total of the cohesion and friction forces along X + Y, and the total lateral driving force (Ft) is the resultant of the Fs forces. The friction forces result from the normal force (Fn) from the sliding soils. The normal force can be determined from the estimated equivalent fluid pressure (EFP) of the soils, or it can be calculated using a sliding wedge based on the unit weight, the internal friction, and the cohesion of the soils, plus the worst angle of sliding, to establish the lateral forces of the soils in any direction, including the normal forces along the cone. The worst situation would occur if the soils at the slide surface are weak and the upper soils that drag along the pile are strong, therefore HEMPHILL calculated the lateral forces on the piles based on an Fn determined by an internal friction value of 30 degrees, which gives a large Fn, and based on the friction value + cohesion for the shear along the cone and the pile, which also gives a high value. HEMPHILL used an EFP of 40 pcf, no cohesion, and an angle of internal friction for the soils of 30 degrees. Those values are conservative since they give higher drag forces than N the friction factor of 20 degrees were used that corresponds to an EFP of 40 pcf. The Friction factor of 30 degrees calculates to an angle of deflection around the pile of 30 degrees. HEMP H I LA- W _J FL J Q Z O Z O U cn LO M LU M 0 LL Aii J. U) I I U) }'I Ul 0 p Z U) OI Or I Q LU Z �I Z W eI CL W I / Q 0 W O 0 H / 0 � cn / Z 0 0 a w o 30 �wLuF5 Ox �wac-'n CL Z w o H ¢UF-OQ� �cgw�ED = 0=I-cn> o _ In JCL :n0Q(i)Z �Zclrj)(n— ca < LLJ � tn�aDWO wait- U - ! Lu LLI N CL u. Q = w f-. - CV C7 0 Z SPIRO RESIDENCE DESIGN of INDIVIDUAL PILES page 44 of 67 pages Figure 35 shows a section of the individual piles with the approximate depths of the piles. The design parameters used by HEMPHILL to design the individual piles, recommended to be an 18 inch diameter concrete pile with a W-10-33 steel beam, are shown on the next page in Figure 36. The pile was chosen based on the bending moment of 49,130 ft Ibs applied by the sliding soils. Also on the next page is Figure 37 which shows the design values for four optional pile lengths. HEMPHILL recommends the 34.5 foot length pile which deflects a maximum of 0.275 inches, has a maximum bending moment of 69,402 ft Ibs, and a maximum shear of 8755 lbs. The maximum bending moment is slightly larger than the allowable of 69,098, which is insignificant. That pile will be placed a minimum of 17.5 feet into the hard Whidbey Clay. FIGURE 36 DESIGN PARAMETERS for INDIVIDUAL PILES A. D E S C R 1 P T I 0 N o f P R O J E C T TRIAL NUMBER 3C PROJECT NUMBER 1636 CLIENT is SPIRO FAMILY PILE CALCULATIONS for SPIRO FAMILY HOUSE LOCATION of PILE is UNDER HOUSE B. S L I D E S O I L D A T A a. HEIGHT from GROUND SURFACE to SLIDE SURFACE 17 ft b. COHESION of SLIDE SOIL 0 psf c. ANGLE of INTERNAL FRICTION of SLIDE SOIL 30 degrees d. EQUIVALENT FLUID PRESSURE of SLIDE SOILS 40 pcf e. ANGLE of DEFLECTION of SLIDE SOILS AROUND PILE 30' degrees f. MAXIMUM SHEAR FORCE BETWEEN SLIDING SOILS and CONE 5,006 psf g. TOTAL SHEAR FORCE in PILE from SLIDING SOILS 8,670 Lbs h. BENDING MOMENT APPLIED by SLIDE SOILS 49,130 ft Lbs C. P I LE DATA 1. S T E E L D A T A a. STEEL BEAM DESIGNATION W-10-33 b. AREA of STEEL BEAM 9.7 sq in c. DEPTH of STEEL BEAM 9.8 inches d. WEB THICKNESS of STEEL BEAM 0.3 inches e. FLANGE WIDTH of STEEL BEAM 8.0 inches f. DIAGONAL DISTANCE ACROSS FLANGES 12.6 inches g. MOMENT of INERTIA of -STEEL BEAM AROUND xx AXIS 171 in\4 h. MODULUS of ELASTICITY of STEEL 29,000;000 psi/in/in i. ALLOWABLE BENDING STRESS of STEEL 23,760 psi j. ALLOWABLE SHEAR STRESS of STEEL 14,500 psi k. ALLOWABLE BENDING MOMENT of STEEL BEAM 69,098 ft Lbs I. ALLOWABLE SHEAR FORCE of STEEL BEAM 45,188 lbs 2. C O N C R E T E D A T A a. COVER for STEEL 2 inches b. DIAMETER of PILE 18 inches c. ULTIMATE STRENGTH of CONCRETE 3,000 psi d. MODULUS of ELASTICITY of COMBINED PILE SECTION 2,994,102 psi e. MOMENT of INERTIA of PILE 6,629 in\4 D. E X T E R N A L F O R C E S a. SHEAR FORCE from STRUCTURE (fr(m STRUCT. ENGR.) 0 Lbs b. TOTAL SHEAR FORCE from SLIDING SOILS + STRUCTURE 8,670 Lbs c. BENDING MOMENT from STRUCTURE (from STRUCT. ENGR.) 0 ft Lbs d. TOTAL BENDING MOMENT from SLIDING SOILS +.STRUCTURE 589,560 in lbs SPIRO RESIDENCE page 45 of 67 pages FIGURE 37 DESIGN of INDIVIDUAL PILES PROJECT NUMBER 1636 TRIAL NUMBER 3C The DESCRIPTION of the RESISTING SOILS is DENSE GRANULAR The LATERAL SOIL MODULUS (RATE of INCREASE WITH DEPTH) = f = 50.2 Pci/ft The STEEL BEAM DESIGNATION is W-10-33 TOTAL LENGTH DEPTH of DEFLECTION (in) BENDING MOMENT (ft Lb) SHEAR (Lb) LENGTH BELOW INVESTIGATN---------------------------- ---------------------------- of PILE SLIP SURF BELOW SLIP MOMENT SHEAR TOTAL MOMENT SHEAR TOTAL MOMENT SHEAR TOTAL MAX ALLOWABLE = 1.000 MAX ALLOWABLE = 69,098 MAX ALLOWABLE = 45,188 25.7 8.7 0.0 +0.261 +0.252 +0.513 +49,130 +0 +49,130 +0 +8,670 +8,670 25.7 8.7 2.2 +0.139 +0.189 +0.327 +45,200 +15,146 +60,346 -3,375 +5,202 +1,827 25.7 8.7 4.4 +0.041 +0.094 +0.135 +31,934 +17,797 +49,731 -8,999 -2,167 -11,167 25.7 8.7 6.6 -0.049 +0.000 -0.049 +9,826 +7,573 +17,399 -8,999 -5,809 -14,808 25.7 8.7 8.7 -0.122 -0.094 -0.217 +0 +0 +0- +0 +0 +0 30.1 13.1 0.0 +0.139 +0.163 +0.302 +49,130 +0 +490130 +0 +8,670 +8,670 30.1 13.1 2.2 +0.057 +0.107 +0.164 +46,673 +17,418 +64,092 -1,687 +6,936 +5,249 30.1 13.1 4.4 +0.024 +0.063 +0.087 +39,304 +26,506 +65,810 -4,500 +1,734 .2,766 30.1 13.1 6.6 +0.000 +0.031 +0.031 +29,478 +23,855 +53,333 -6,187 -3,034 -9,222 30.1 13.1 8.7 -0.016 +0.000 -0.016 +14,739 +15,146 +29,885 -6,187 -5,202 -11,389 30.1 13.1 10.9 -0.024 -0.019 -0.043 +4,913 +3,787 +8,700 -4,162 -4,335 -8,497 30.1 13.1 13.1 -0.033 -0.031 -0.064 +0 +0 +0 +0 +0 +0 34.5 17.5 0.0 +0.131 +0.145 +0.275 +49,130 +0 +49,130 +0 +8,670 +8,670 34.5 17.5 2.2 +0.057 +0.094 +0.151 +47,165 +17,418 +64,583 -1,687 +6,936 +5,249 34.5 17.5 4.4 +0.020 +0.050 +0.071 +41,760 +27,642 +69,402 -4,162 +2,601 -1,561 34.5 17.5 6.6 +0.000 +0.019 +0.019 +29,969 +28,020 +57,990 -5,287 -1,300 -6,588 34.5 17.5 8.7 -0.016 +0.006 -0.010 +19,652 +23,476 +43,128 -5,287 .-3,468 -8,755 34.5 17.5 10.9 -0.016 -0.006 -0.023 +9,826 +15,146 +24,972 -4,162 "'-3,641 -7,804 34.5 17.5 .13.1 -0.012 -0.013 -0.025 +1,474 +7,573 +9,047 -2,587 -3,034 -5,622 34.5 17.5 15.3 -0.008 -0.013 -0.021 +491 +1,136 +1,627 -1,125 -1,734 -2,859 34.5 17.5 17.5 -0.004 -0.013 -0.017 +0 +0 +0 +0 +0 +0 38.8 21.8 0.0 +0.131 +0.145 +0.275 +49,130 +0 +49,130 +0 +8,670 +8,670 38.8 21.8 2.2 +0.057 +0.094 +0.151 +47,165 +17,418 +64,583 -1,687 +6,936 +5,249 38.8 21.8 4.4 +0.020 +0.050 +0.071 +41,760 +27,642 +69,402 -4,162 +2,601 -1,561 38.8 21.8 6.6 +0.000 +0.019 +0.019 +29,969 +28,020 +57,990 -5,287 -1,300 -6,588 38.8 21.8 8.7 -0.016 +0.006 -0.010 +19,652 +23,476 +43,128 -5,287 -3,468 -8,755 38.8 21.8 10.9 -0.016 -0.006 -0.023 +9,826 +15,146 +24,972 -4,162 -3,641 -7,804 38.8 21.8 13.1 -0.012 -0.013 -0.025 +1,965 +7,573 +9,538 -2,587 -3,034 -5,622 38.8 21.8 15.3 -0.008 -0.013 -0.021 -1,474 +2,651 +1,177 -1,125 -1,734 -2,859 38.8 21.8 17.5 -0.004 -0.013 -0.017 -2,456 +757 -1,699 +0 -867 -867 38.8 21.8 19.7 +0.000 +0.000 +0.000 +0 +0 +0 +337 +0 +337 FIGURE 33 RETAINING WALL PILE DESIGN PARAMETERS D E S C R I P T I O N o f P R O J E C T CALCULATION TRIAL NUMBER 2A PROJECT NUMBER 1636 CLIENT is SPIRO FAMILY PILE CALCULATIONS for SPIRO FAMILY HOUSE LOCATION of SOLDIER PILE WALL is at NORTHEAST CORNER of HOUSE S O I L D A T A ACTIVE SOIL DESCRIPTION (BEHIND SOLDIER PILE WALL) is GRANULAR STRUCTURAL FILL RATE of CHANGE of SOIL MODULUS (f) = 50 pci/ft ESTIMATED EQUIVALENT FLUID PRESSURE of SOILS BEHIND WALL = 30 pcf GAP BETWEEN LAGGING and TOP of LATERAL RESISTING SOILS = 15 ft RANGE of WALL HEIGHT THAT SUPPORTS LATERAL FORCES = 7 to 9 ft P I L E S T E E L S E C T I O N D E S I G N D A T A A. STEEL BEAM SECTION PROPOSED for SOLDIER PILES = W-12-58 B: MOMENT of INERTIA of STEEL BEAM SECTION (X AXIS) = 476 in\4 C. MOMENT of INERTIA of STEEL BEAM SECTION (Y AXIS) = 107 in\4 D. DEPTH of STEEL BEAM = 12.2 in E. FLANGE WIDTH of STEEL BEAM = 10.0 in F. THICKNESS of WEB of STEEL BEAM = 0.4 in G. MODULUS of ELASTICITY of STEEL = 29,000,000 psi/in/in H. MAXIMUM ALLOWABLE BENDING STRESS in STEEL BEAM = 24,000 psi I. MAXIMUM ALLOWABLE SHEAR STRESS in STEEL BEAM = 14,500 psi J. MAXIMUM ALLOWABLE LATERAL DEFLECTION of STEEL PILE = 1.000 in C O N C R E T E S E C T I O N K. DIAGONAL DISTANCE ACROSS STEEL SECTION = 15.8 inches L. MINIMUM PROTECTIVE COVER for STEEL = 2.0 inches M. DIAMETER of CONCRETE SECTION of PILE = 20 inches N. MODULUS of ELASTICITY of CONCRETE = 3,000,000 psi 0. ULTIMATE STRENGTH of CONCRETE = 3,000 psi C O M B I N E D S E C T I O N P. MODULUS of ELASTICITY used for COMBINED PILE SECTION = 3,000,000 psi Q. MOMENT of INERTIA USED for COMBINED SECTION of PILE = 12,125 in\4 SPIRO RESIDENCE page 46 of 67 pages RETAINING WALL PILES Figure 32 on page 40 shows the locations of the retaining foundation walls and piles in red, which will include piles 8, 7, 11, 17, and 16. Although Pile 4 will help to support the retaining wall, it will not be designed as a retaining wall pile. Pile 4 will not be designed for lateral soil pressures on the wall because the fill soils range from 1 to 4 feet along the half of wall between Piles 4 and 8 supported by Pile 4. The walls will be similar to a soldier pile wall supported at the base by lateral resisting piles constructed with steel beams encased in concrete. The steel beams then extend above the concrete encasing to support the reinforced concrete wall. The wall is constructed by welding the horizontal reinforcing steel to the webs of the steel beams, except for Pile 4 which will be designed as an individual pile, and the steel for the retaining wall will be welded to the flange. Piles 8 and 17 should be turned 45 degrees so that the wall steel will be welded to the webs. That will cause the components of the backfill forces from the adiacent walls to be perpendicular to the flange, which is the direction of the design of the piles to resist the permanent backfill soils. The direction parallel to the flanges can still resist the potential sliding soils. Pile 11 can be turned 22.5 degrees, and pile 11 can be turned 67.5 degrees, from the directions that the numbers show on Figure 32. Pile 16 will only support half the wall between Piles 16 and 17, but since that is a long wall (10 ft) the pile size will not be reduced. The retaining foundation walls will always be supporting the backfill soils for the driveway, therefore the flanges of the beams will be perpendicular to the direction of the lateral forces from the backfill soils. If a slide should occur, it will occur more downslope to the west, therefore perpendicular to the forces from the backfill soils. HEMPHILL determined that the piles must be designed to resist the permanent loads of the backfill soils against the retaining wall, plus the temporary loads of sliding soils against the piles themselves acting perpendicular to the retaining wall loads; therefore the piles must be designed with a steel beam that has a high moment of inertia around the Y axis. The design parameters, described below, that are used to design the retaining wall piles (W-12-58) are shown in Figure 38. The same design parameters were used to check those piles for soil drag along the pile perpendicular to the wall forces, which would bend the pile around the Y axis, except the flange width and the beam depth were reversed, and the Y axis moment of inertia of 107 in4 was used. LATERAL DRIVING PRESSURES on RETAINING WALLS The lateral driving pressures against the retaining walls will exist regardless of any sliding of the lower soils. HEMPHILL assumed the lateral driving pressures against the retaining foundation wall to be the result of well placed structural fill, and based on a soil with no cohesion and an internal friction factor of 0.5, also defined as 26.5 degrees, which is approximately equal to 30 pcf equivalent fluid pressure. FIGURE 39 ' DESIGN of RETAINING WALL PILES IRO FAMILY HOUSE PROJECT NUMBER 1636 TRIAL NUMBER 2A e DESCRIPTION of the DRIVING SOILS is GRANULAR STRUCTURAL FILL e DESCRIPTION of the RESISTING SOILS is DENSE GRANULAR e LATERAL SOIL MODULUS (RATE of INCREASE WITH DEPTH) = f = 50.2 pci / ft e STEEL BEAM DESIGNATION is W-12-58 IGHT SPACING TOTAL LENGTH DEPTH DEFLECTION (in) BENDING MOMENT (ft Lb) SHEAR (lb) of of LENGTH BELOW from -------------------------- ------------------------------- ------------------- ALL ---- PILES ------- of PILE ------- SURFACE ------- SURFACE ------- MOMENT -------- SHEAR ------- TOTAL ------- MOMENT --------- SHEAR --------- TOTAL --------- MOMENT -------- SHEAR ------- TOTAL ------- MAX ALLOWABLE = 1.000 MAX ALLOWABLE = 156,194 MAX ALLOWABLE = 63,455 7 8 35 13.4 0.0 +0.163 +0.064 +0.227 +101,920 +0 +101,920 +0 +5,880 t +5,880 7 8 35 13.4 2.2 +0.067 +0.042 +0.109 +96,824 +12,039 +108,863 -3,435 +4,704 +1,269 7 8 35 13.4 4.5 +0.029 +0.025 +0.053 +81,536 +18,321 +99,857 -9,159 +1,176 -7,983 7 8 35 13.4 6.7 +0.000 +0.012 +0.012 +61,152 +16,489 +77,641 -12,594 -2,058 -14,652 7 8 35 13.4 8.9 -0.019 +0.000 -0.019 +30,576 +10,469 +41,045 -12,594 •-3,528 -16,122 7 8 35 13.4 11.1 -0.029 -0.007 -0.036 +10,192 +2,617 +12,809 -8,472 -2,940 -11,412 7 8 35 13.4 13.4 -0.038 -0.012 -0.051 +0 +0 +0 +0 +0 +0 7 9 35 13:4 0.0 +0.183 +0.072 +0.256 +114,660 +0 +114,660 +0 +6,615 +6,615 7 9 35 13.4 2.2 +0.076+0.047 +0.123 +108,927 +13,544 +122,471 -3,864 +5,292 +1,428 7 9 35 13.4 4.5 +0.032 +0.028 +0.060 +91,728 +20,611 +112,339 -10,304 +1,323 -8,981 7 9 35 13.4 6.7 +0.000 +0.014 +0.014 +68,796 +18,550 +87,346 -14,168 -2,315 -16,483 7 9 35 13.4 8.9 -0.022 +0.000 -0.022 +34,398 +11,778 . +46,176 -14,168 -3,969 -18,137 7 9 35 13.4 11.1 -0.032 -0.008 -0.041 +11,466 +2,944 +14,410 -9,531 -3,308 -12,839 7 9 35 13.4 13.4 -0.043 -0.014 -0.057 +0 +0 +0 +0 +0 +0 8 8 36 13.4 0.0 +0.217 +0.084 +0.301 +135,680 +0 +135,680 +0 +7,680 +7,680 8 8 36 13.4 2.2 +0.089 +0.055 +0.144 +128,896 +15,725 +144,621 -4,572 +6,144 +1,572 8 8 36 13.4 4.5 +0.038 +0.032 +0.070 +108,544 +23,929 +132,473 -12,193 +1,536 -10,657 8 8 36 13.4 6.7 +0.000 +0.016 +0.016 +81,408 +21,536 +102,944 -16,765 -2,688 -19,453 8 8 36 13.4 8.9 -0.026 +0.000 -0.026 +40,704 +13,674 +54,378 -16,765 -4,608 -21,373 8 8 36 13.4 11.1 -0.038 -0.010 -0.048 +13,568 +3,418 +16,986 -11,278 -3,840 -15,118 8 8 36 13.4 13.4 -0.051 -0.016 -0.067 +0 +0 +0 +0 +0 +0 8 9 36 13,4 0.0 +0.244 +0.094 +0.338 +152,640 +0 +152,640 +0 +8,640 +8,640 8 9 36 13.4 2.2 +0.101 +0.062 +0.162 +145,008 +17,691 +162,699 -5,144 +6,912 +1,768 8 9 36 13.4 4.5 +0.043 +0.036 +0.079 +122,112 +26,920 +149,033 -13,717 +1,728 -11,989 8 9 36 13.4 6.7 +0.000 +0.018 +0.018 +91,584 +24,228 +115,812 -18,861 -3,024 -21,885 8 9 36 13.4 8.9 -0.029 +0.000 -0.029 +45,792 +15,383 +61,175 -18,861 -5,184 -24,045 8 9 36 13.4 11.1 -0.043 -0.011 -0.054 +15,264 +3,846 +19,110 -12,688 -4,320 -17,008 8 9 36 13.4 13.4 -0.057 -0.018 -0.076 +0 +0 +0 +0 +0 +0 9 8 37 13.4 0.0 +0.280 +0.106 +0.386 +174,960 +0 +174,960 +0 +9,720 +9,720 9 8 37 13.4 2.2 +0.115 +0.069 +0.184 +166,212 +19,902 +186,114 -5,896 +7,776 +1,880 9 8 37 13.4 4.5 +0.049 +0.041 +0.090 +139,968 +30,286 +170,254 -15,723 +1,944 -13,779 9 8 37 13.4 6.7 +0.000 +0.020 +0.020 +104,976 +27,257 +132,233 -21,619 -3,402 -25,021 9 8 37 13.4 8.9 -0.033 +0.000 -0.033 +52,488 +17,306 +69,794 -21,619 -5,832 -27,451 9 8 37 13.4 11.1 -0.049 -0.012 -0.062 +17,496 +4,327 +21,823 -14,544 -4,860 -19,404 9 8 .37 13.4 13.4 -0.066 -0.020 -0.086 +0 +0 +0 +0 +0 +0 SPIRO RESIDENCE page 47 of 67 pages The greatest possible total moment on the retaining foundation wall piles was determined based on a space of 15' between the bottom of the wall and the hard lateral resisting clay, which is the worst possible condition, therefore the maximum possible moment on the pile is: r {f (30 pcf x 9' height2) / 2] x 8' wide} x 18' lever = 175,000 ft Ibs The lever arm used was for a 9 foot wall and is the sum of 15 feet from the top of the hard clay to the base of the excavated crawl space (bottom of the wall) plus 3 feet to the centroid of the lateral forces from the non -cohesive soils against the wall. DESIGN of RETAINING WALL PILES Figure 39 shows the calculated values for deflection, bending moment, and shear resulting from both moment and shear, and then shows the totals. Those values are shown at several different positions on the piles from the top of the hard clay. Figure 39 shows 5 different wall height and pile spacing combinations, then shows the total length' of the pile from the bottom of the wall, then the: depth into the hard clay, and then shows the depth into the clay that is being investigated. The total length of pile of approximately 35 to 37 feet will be used, with 13.4 feet of embedment into the hard clay. Figure 40 on the next page shows the calculations to check the deflection, bending, and shear of the retaining wall piles around the Y axis caused by the drag of the sliding soils. DEFLECTION of the PILES The deflections shown in Figure 39 would be for a situation where the upper unstable soils had slid. Prior to that time, if ever, the upper soils will help to resist deflection of the piles from loads on the walls. Therefore the deflections shown in Figure 39 will actually exist if the upper soils should creep around the piles, but otherwise will not occur until sliding occurs, and then only if the driveway soils do not also slide. The deflections shown in Figure 40 result from drag of the potential sliding soils acting to the west and perpendicular to the web of the beam in the pile. The deflections shown are at the top of the clay, and then they extend up to the house, but projections show that the deflections are still less than the allowable 1 inch. E HILL FIGURE 40 SLIDE FORCES on RETAINING WALL PILES PROJECT NUMBER 1636 TRIAL NUMBER 3E The DESCRIPTION of the RESISTING SOILS is DENSE GRANULAR The LATERAL SOIL MODULUS (RATE of INCREASE WITH DEPTH) = f = 50.2 pci/ft The STEEL BEAM DESIGNATION is W-12-58 TOTAL LENGTH DEPTH of DEFLECTION (in) BENDING MOMENT (ft lb) SHEAR (Lb) LENGTH BELOW INVESTIGATN ____________________________ -------------------------------- -------------------------------- ---------------------------- ---------------------------- of PILE ------- ------- SLIP SURF --------- --------- BELOW SLIP --------- --------- MOMENT -------- -------- SHEAR ------- ------- TOTAL ------- ------- MOMENT -------- -------- SHEAR --------- --------- TOTAL --------- --------- MOMENT -------- -------- SHEAR ------- ------- TOTAL ------- ------- MAX ALLOWABLE = 1.000 MAX ALLOWABLE = 42,313 MAX ALLOWABLE = 52,128 24.2 9.2 0.0 +0.126 +0.146 +0.272 +28,125 +0 +28,125 +0 +5,625 +5,625 24.2 9.2 2.3 +0.067 +0.109 +0.177 +25,875 +10,392 +36,267 -1,827 +3,375 +1,548 24.2 9.2 4.6 +0.020 +0.055 +0.074 +18,281 +12,211 +30,492 -4,871 -1,406 -6,278 24.2 9.2 6.9 -0.024 +0.000 -0.024 +5,625 +5,196 +10,821 -4,871 -3,769 -8,640 24.2 9.2 9.2 -0.059 -0.055 -0.114 +0 +0 +0 +0 +0 +0 28.9 13.9 0.0 +0.067 +0.095 +0.162 +28,125 +0 +28,125 +0 +5,625 +5,625 28.9 13.9 2.3 +0.028 +0.062 +0.090 +26,719 +11,951 +38;670 -913 +4,500 +3,587 28.9 13.9 4.6 +0.012 +0.036 +0.048 +22,500 +18,186 +40,686 -2,436 +1,125 -1,311 28.9 13.9 6.9 +0.000 +0.018 +0.018 +16,875 +16,368 +33,243 -3,349 -1,969 -5,318 28.9 13.9 9.2 -0.008 +0.000 -0.008 +8,438 +10,392 +18,830 -3,349 -3,375 -6,724 28.9 13.9 11.5 -0.012 -0.011 -0.023 +2,813 +2,598 +5,411 -2,253 -2,813 -5,066 28.9 13.9 13.9 -0.016 -0.018 -0.034 +0 +0 +0 +0 +0 +0 33.5 18.5 0.0 +0.063 +0.084 +0.147 +28,125 +0 +28,125 +0 +5,625 +5,625 33.5 18.5 2.3 +0.028 +0.055 +0.082 +27,000 +11,951 +38,951 -913 +4,500 +3,587 33.5 18.5 4.6 +0.010 +0.029 +0.039 +23,906 +18,966 +42,872 -2,253 +1,688 -566 33.5 18.5 6.9 +0.000 +0.011 +0.011 +17,156 +19,226 +36,382 -2,862 -844 -3,706 33.5 18.5 9.2 -0.008 +0.004 -0.004 +11,250 +16,108 +27,358 -2,862 -2,250 -5,112 33.5 18.5 11.5 -0.008 -0.004 -0.012 +5,625 +10,392 +16,017 -2,253 -2,363 -4,616 33.5 18.5 13.9 -0.006 -0.007 -0.013 +844 +5,196 +6,040 -1,401 -1,969 -3,369 33.5 18.5 16.2 -0.004 -0.007 -0.011 +281 +779 +1,061 -609 -1,125 -1,734 33.5 18.5 18.5 -0.002 -0.007 -0.009 +0 +0 +0 +0 +0 +0 38.1 23.1 0.0 +0.063 +0.084 +0.147 +28,125 +0 +28,125 +0 +5,625 +5,625 38.1 23.1 2.3 +0.028 +0.055 +0.082 +27,000 +11,951 +38,951 -913 +4,500 +3,587 38.1 23.1 4.6 +0.010 +0.029 +0.039 +23,906 +18,966 +42,872 -2,253 +1,688 -566 38.1 23.1 6.9 +0.000 +0.011 +0.011 +17,156 +19,226 +36,382 -2,862 -844 -3,706 38.1 23.1 9.2 -0.008 +0.004 -0.004 +11,250 +16,108 +27,358 -2,862 -2,250 -5,112 38.1 23.1 11.5 -0.008 -0.004 -0.012 +5,625 +10,392 +16,017 -2,253 -2,363 -4,616 38.1 23.1 13.9 -0.006 -0.007 -0.013 +1,125 +5,196 +6,321 -1,401 -1,969 -3,369 38.1 23.1 16.2 -0.004 -0.007 -0.011 -844 +1,819 +975 -609 -1,125 -1,734 38.1 23.1 18.5 -0.002 -0.007 -0.009 -1,406 +520 -887 +0 -563 -563 38.1 23.1 20.8 +0.000 +0.000 +0.000 +0 +0 +0 +183 +0 +183 SPIRO RESIDENCE BENDING of the PILES page 48 of 67 pages The bending moment of the piles shown in Figure 39 for various heights of soil against the walls, for various spacing of the piles, and at various depths along the piles, show that the actual bending moment does not exceed the allowable except for the 9 foot high wall with 8 foot spacing, but the maximum bending moment of 186,114 ft Ibs still has a safety factor of 1.3 even with the conservative soil values used by HEMPHILL Figure 40 shows the bending moments around the Y axis. Although the total length of pile of 28.9 could be used, the length of 35 to 37 feet is required for resisting the wall loads, therefore the depths for sliding loads will be more conservative. The maximum bending moment will be 42,872 ft Ibs, which exceeds the allowable of 42,313 ft Ibs, but the difference is insignificant. RESISTANCE to OVERTURNING The overturning of the retaining foundation wall will be resisted by the rigidity of the wall and the pile system, and possibly by the resistance of the upper structure against the wall if so designed by the structural engineer. VERTICAL SUPPORT The more than 3 sf area at the end of the pile will give an end bearing force of approximately 20,000 pounds. Each additional 1' of pile placed into the Whidbey Clay will offer a force of approximately 6,000 pounds of friction, for a total of 80,000 pounds for 10' of embedment, which far exceeds the required vertical support. PRECAUTIONS for CONTRACTOR Generally, any damage to foundation walls and adjacent structures occurs at the time of construction because of poor construction practices. Compaction adjacent to the foundation' walls should not be conducted until the concrete has cured to an acceptable strength in accordance with the recommendations of the structural engineer, or 30 days with normal concrete, and 7 days with high early concrete. Compaction adjacent to the foundation walls should be accomplished with light hand operated equipment within a distance of the outside of the foundation wall equal to the height of the fill, so that no excessive lateral pressures are applied to the structure. The fill should be placed in layers no thicker than 8• after compaction to achieve proper compaction, and to reduce lateral pressures on the wall from loose soil. HEAVY EXCAVATING EQUIPMENT SHOULD- NEVER BE USED TO PLACE OR TO COMPACT STRUCTURAL FILL ADJACENT TO STRUCTURES. w z O - A Z V V Q LLI O - W z C' 0Y A w z O O_ LLI 0 O -- A �- Q V H ? Q Z U F- Z c� w Q Q -' Q Z S cn J A F- A O O uj - to Z S Of w F • a. O F- Q F- cL W F W z W A W D_ tr O S Q = A O O V F- 0: w W w Z O cn O A A W Q } F- W LLJ A G3 Z J Q F- Z w w a. cn A A Q --• > C7 w w > E O z r O >- A Q S W F- Z F- J U W IL F- = ui X F- CL O_ J 3 F- 3 w w Q w Q Z S A A rY w O F- cn A S - U U J W w ♦- J W F- Z cy- W En W a. J S U Q (7 O z O w Q F- O A Z L1._ Z W Z A 3 < W O Q cn F- O tY U O S (n to U Q Lli U �- F- F- W V > > • J >- Q Q W O O w w 3 CO V 3 F- F- D (D Z X S F- Lt) Z .J Q > W N O W F- z z J Q O C) Q F- a_ .O O Q> w Q O LLI U U = Q a. z 0 Z cn A Q U CL Z W w a_ X Q Q S Q w O O w c7 F- UJ S to J A 0 C7 CO F- 0- w A -- Q Z O J (9 W F- J W H F- J Z V) Z O S Q Q O LL W F- S O S J O_ U fn F- F- a. LL O W Q p - = O U J W 3 O S S W S a. Q CL F_ F_ to F- F- S F- CL w A a. CL W to to of w Z W W >- 3 O >- W U U O A A W Q 3 J Z Q CO S A O Rl O J. - H A E C7 Z F-- J Q U a_ �S z Z --+ a_ w J F- W > Q Z - = W W Q (n I W W = O A = Z = Z _1 Z O A = - = W W -- w W CO O F-- V) U Z C7 J i Z F- W w = w z W W - = J a 1 O O w U a- A O w O — Q LL U Q w A F- LL d J U U- w F- S W W In F- M Q rr S Q F- Q to O J O O O: O. F- E a. w u w 3 r-- . z LL V) W F- Z J F- O F- W W F- _ A Z O — (n O W V A O cn W U a. Z A J Z LL) LL u w W O of F- O H O F- M 3 U N CL F- z Q -- O F- - - Z a: C7 w O W 3 F- W J J>- A w - CA to Cq J J CJ C7 CO S J F- W •-• C'7 d: U) A O Q 2 J Cl W --' W S V O h- a- a- J J W J Cr Q i > CO J W LLI O > W W W J O J U J Z Q S = U J Q J U Q ►- a- tn W tr W J O X LL LL J W a_ w. w A > a. w A w O O a- A Q Q CO U A W LL (D S SPIRO RESIDENCE page 49 of 67 pages DESIGN of SOLDIER PILE WALL The soldier pile wall, located as shown in Figure 32 on page 40, and shown in section in Figure 41, will support the rear slope after the excavations have been conducted for the garage and the driveway. The soldier piles will be placed prior to the excavating process to protect the slope from sliding after the toe of the slope has been removed. HEMPHILL assumed that the piles for the soldier pile wall will be placed into the hard clay with no other soils below the bottom of the excavation, therefore the entire length of the supporting sections of the piles will be in stable soils. Figure 42 shows the process for constructing a soldier pile wall, including the 90 degree turn at the south end of the wall. FIGURE 41 SECTION of SOLDIER PILE WALL FIGURE 44 DESIGN of SOLDIER PILE WALL IRO FAMILY HOUSE PROJECT NUMBER 1636 TRIAL NUMBER 7 e DESCRIPTION of the DRIVING SOILS is STRUCTURAL FILL & SLOPE SLOUGH e DESCRIPTION of the RESISTING SOILS is DENSE GRANULAR e LATERAL SOIL MODULUS (RATE of INCREASE WITH DEPTH) = f = 50.2 pci / ft e STEEL BEAM DESIGNATION is W-8-28 IGHT SPACING TOTAL LENGTH DEPTH DEFLECTION (in) BENDING MOMENT (ft lb) SHEAR (lb) of of LENGTH BELOW from -------- ------------------ ------------------------------- -------------------------- ALL PILES of PILE SURFACE SURFACE MOMENT SHEAR TOTAL " MOMENT SHEAR TOTAL MOMENT SHEAR TOTAL MAX ALLOWABLE = 2.000 MAX ALLOWABLE = 48,536 MAX ALLOWABLE = 33,308 6 10 14 7.5 0.0 +0.068 +0.159 +0.227 +10,800 +0 +10,800 +0 +5,400 +5,400 6 10 14 7.5 1.9 +0.036 +0.119 +0.156 +9,936 +8,103 +18,039 -864 +3,,240 +2,376 6 10 14 7.5 3.8 +0.011 +0.060 +0.070 +7,020 +9,521 +16,541 -2,303 -1,350 -3,653 6 10 14 7.5 5.6 -0.013 +0.000 -0.013 +2,160 +4,051 +6,211 -2,303 -3,618 -5,921 6 10 14 7.5 7.5 -0.032 -0.060 -0.092 +0 +0 +0 +0 +0 +0 7 10 15 7.5 0.0 +0.108 +0.217 +0.325 +17,150 +0 +17,150 +0 +7,350 +7,350 7 10 15 7.5 1.9 +0.057 +0.163 +0.220 +15,778 +11,029 +26,807 -1,372 +4,410 +3,038 7 10 15 7.5 3.8 +0.017 +0.081 +0.098 +11,148 +12,959 +24,107 -3,657 -1,838 -5,495 7 10 15 7.5 5.6 -0.020 +0.000 -0.020 +3,430 +5,514 +8,944 -3,657 -4,925 -8,582 7 10 15 7.5 7.5 -0.051 -0.081 -0.132 +0 +0 +0 +0 +0 +0 8 10 16 7.5 0.0 +0.161 +0.283 +0.444 +25,600 +0 +25,600 +0 +9,600 +9,600 8 10 16 7.5 1.9 +0.086 +0.212 +0.298 +23,552 +14,405 +37,957 -2,047 +5,760 +3,713 8 10 16 7.5 3.8 +0.025 +0.106 +0.131 +16,640 +16,926 +33,566 -5,459 -2,400 -7,859 8 10 16 7.5 5.6 -0.030 +0.000 -0.030 +5,120 +7,203 +12,323 -5,459 -6,432 -11,891 8 10 16 7.5 7.5 -0.075 -0.106 -0.182 +0 +0 +0 +0 +0 +0 9 8 20 11.3 0.0 +0.097 +0.186 +0.284 +29,160 +0 +29,160 +0 +9,720 +9,720 9 8 20 11.3 1.9 +0.040 +0.122 +0.162 +27,702 +16,773 +44,475 -1,166 +7,776 +6,610 9 8 20 11.3 3.8 +0.017 +0.072 +0.089 +23,328 +25,524 +48,852 -3,109 +1,944 -1,165 91 8 20 11.3 5.6 +0.000 +0.036 +0.036 +17,496 +22,972 +40,468 -4,275 -3,402 -7,677 9 8 20 11.3 7.5 -0.011 +0.000 -0.011 +8,748 +14,585 +23,333 .4,275 -5,832 -10,107 9 8 20 11.3 9.4 -0.017 -0.021 -0.039 +2,916 +3,646 +6,562 -2,876 -4,860 -7,736 9 8 20 11.3 11.3 -0.023 -0.036 -0.059 +0 +0 +0 +0 +0 +0 10 6 21 11.3 0.0 +0.100 +0.173 +0.273 +30,000 +0 +30,000 +0 +9,000 +9,000 10 6 21 11.3 1.9 +0.041 +0.113 +0.154 +28,500 +15,531 +44,031 -1,200 +7,200 +6,000 10 6 21 11.3 3.8 +0.018 +0.066 +0.084 +24,000 +23,633 . +47,633 -3,199 +1,800 -1,399 10 6 21 11.3 5.6 +0.000 +0.033 +0.033 +18,000 +21,270 +39,270 -4,398 -3,150 -7,548 10 6 21 11.3 7.5 -0.012 +0.000 -0.012 +9,000 +13,505 +22,505 -4,398 -5,400 -9,798 10 6 21 11.3 9.4 -0.018 -0.020 -0.038 +3,000 +3,376 +6,376 -2,959 -4,500 -7,459 10 6 21 11.3 11.3 -0.024 -0.033 -0.057 +0 +0 +0 +0 +0 +0 4 SPIRO RESIDENCE page 50 of 67 pages Figure 43 shows the parameters used to design the soldier pile wall, which included lateral forces based on an equivalent fluid pressure of 30 pcf; a wall height that ranges from 6 to 10 feet, no gap between the bottom of the wall and the hard soils, and spacings between piles ranging from 6 to 10 feet. The chosen pile W-8-28 was for its wide flange, and the ability to support a 10 foot high wall with 6 foot spacings, a 9 foot high wall with 8 foot spacings, and an 8 foot wall with 10 foot spacings, as shown in Figure 44 on the opposite page. FIGURE 43 SOLDIER PILE DESIGN PARAMETERS. S O I L D A T A ACTIVE SOIL DESCRIPTION (BEHIND SOLDIER PILE -WALL) is STRUCTURAL FILL & SLOPE SLOUGH RATE of CHANGE of SOIL MODULUS (f) = 50 pci/ft ESTIMATED EQUIVALENT FLUID PRESSURE of SOILS BEHIND WALL = 30 pcf GAP BETWEEN LAGGING and TOP of LATERAL RESISTING SOILS = 0 ft RANGE of WALL HEIGHT THAT SUPPORTS LATERAL FORCES = 6 to, 10 ft P I L E STEEL SECTION D E S I G N D A T A A. STEEL BEAM SECTION PROPOSED for SOLDIER PILES B. MOMENT of INERTIA of STEEL BEAM SECTION (X AXIS) C. MOMENT of INERTIA of STEEL BEAM SECTION (Y AXIS) D. DEPTH of STEEL BEAM E. FLANGE WIDTH of STEEL BEAM F. THICKNESS of WEB of STEEL BEAM G. MODULUS of ELASTICITY of STEEL H. MAXIMUM ALLOWABLE BENDING STRESS in STEEL BEAM I. MAXIMUM ALLOWABLE SHEAR STRESS in STEEL BEAM J. MAXIMUM ALLOWABLE LATERAL DEFLECTION of STEEL PILE CONCRETE SECTION = W-8-28 98 in\4 22 i n\4 8.1 in 6.5 in 0.3 in 29,000,000 psi/in/in 24,000 psi 14,500 psi 2.000 in K. DIAGONAL DISTANCE ACROSS STEEL SECTION = 10.4 inches L. MINIMUM PROTECTIVE COVER for STEEL 2.0 inches M. DIAMETER of CONCRETE SECTION of PILE = 16 inches N. MODULUS of ELASTICITY of CONCRETE = 3,000,0010 psi 0. ULTIMATE STRENGTH of CONCRETE = 3,000. psi C O M B I N E D S E C T I O N P. MODULUS of ELASTICITY used for COMBINED PILE SECTION = 3,000,000 psi Q. MOMENT of INERTIA USED for COMBINED SECTION of PILE = 4,124 in\4 HE IN-119 PH I I_ L Qcn m uj m m m LLJ m W �... W m FL oU �-o o>. cc hoc o a. Q z C� w I— U w— o oc o a LO R* oWC C) LL I_� _1 zCC Z >- O m O p oC = CC pap r c g 0 a: W cc °- > a a W >� Cr � U U C 0 w z Uj0 p W z z z 0 a o 0. cr a � w >O J CC 0cc W U V J z �t W W Q M O 0 a 0 SPIRO RESIDENCE page 51 of 67 pages CONCRETE GARAGE FLOOR SLAB PREPARATION of BASE COURSE for GARAGE FLOOR SLAB The east half of the garage floor slab will be placed over the excavated soils. Since it has been determined that there is a source of moisture that could be conducted by capillary action to contact the underside of the garage floor slab, then the floor slab should be underlain by a capillary break to stop the capillary water. Figure 45 shows an example of a capillary break. Capillary water can create dampness at the surface of the garage floor which will penetrate any boxes, paper, or wood materials, and will rust any metal placed on the floor. PROTECTION of GARAGE FLOOR SLAB from CAPILLARY WATER A capillary break is a soil that will not conduct capillary water to the underside of the garage floor slab. The source of capillary water could be either the groundwater table or surface drainage. Different soils have different maximum heights of capillary rise, therefore the effectiveness of a soil as a capillary break depends on the capillarity of the soil and the height from the water source to the floor slab. HEMPHILL has determined that the existing soils are not an effective capillary break, therefore the garage floor slab should be underlain by a capillary break composed of a 4 inch layer of aggregate with a minimum size equal to approximately 1/4 inch. It might be necessary for the capillary break to be underlain by a filter or filter soil to prevent the integration of the underlying soils and the capillary break aggregates. If required, then the proper filter soil or material should be determined by HEMPHILL in accordance with the available materials at the time of construction. A plastic vapor barrier can be placed on top of the capillary break aggregate to prevent the condensation of vapor on the underside of the concrete floor slab. The plastic will also prevent the loss of water from the bottom of the slab during the curing process to minimize differential curing, provided that the loss of water is also prevented from the top of the slab. The lower the water/cement ratio of the floor slab concrete, and the longer the concrete is properly cured, the stronger the concrete will be, the more resistant the slab will be to moisture, and the concrete will be more resistant to cracking from both curing shrinkage and temperature changes. Because the garage floor is a structural slab, the proper water cement ratio must be maintained, and the cement finishers must not add excessive water to reduce their labor. Also, a lower water/cement ratio gives the cement finishers less water to work to the surface, which then gives a more wear resistant surface, and allows less differential shrinkage between the top and bottom surfaces of the slab, and therefore less spider web cracks. _.-FIGURE 46 LOCATION. of_ROOKERY 10 - r - -r- �o� —tA " .' ? 1 \ I a ••- � � idGt :J , , aLm..s. J ilk 9 Fnx tk SPIRO RESIDENCE page 52 of 67 pages ROCKERY DESIGN and CONSTRUCTION LOCATION of ROCKERY The proposed rockery will support the driveway and will act as an extension of the wall between piles 16 and 17, located as shown in Figure 46. 3 METHODS of FAILURE of ROCKERIES 1. SUDING BETWEEN ROCKS The lateral pressures behind the rockery caused by the soils that the rockery is supporting are resisted by the friction forces between the rocks. The friction forces are determined by the weight of all the rocks above. The greater the weight of the rocks above an intersection between 2 rocks, the greater the friction force at that intersection that will resist sliding. The resistance to sliding can be increased by tipping the rockery back so that the upper rock must slide uphill on the lower rock. The resistance can also be increased by wedging the rocks so that peaks and valleys are interlocked. That value cannot be considered in the design of a rockery because it is dependent on the shape of the rocks and the way that the rocks are placed, which can vary greatly throughout a rockery. The values of friction are determined assuming smooth surfaces and ignoring the large peaks and valleys. The values of friction are fairly consistent, and generally are not dependent on the area of contact between the two rocks, but good construction practice would require that each rock should be placed so that there is a large area of contact between the rocks. 2. OVERTURNING BETWEEN ROCKS Overturning can occur at any intersection between two rocks. The upper portion of the rockery will rotate at the outermost point of contact if overturning occurs. If the outermost point of contact is at the outer edge of the upper rock, then the rocks above have the greatest resistance to overturning. If the outermost point of contact is somewhere inside the outer edge of the upper rock, then the resistance to overturning will be decreased in direct proportion to the distance from the backside of the rock to the point of contact. When the minimum allowable thickness of rockery at a section is required to resist sliding, then the pivot point of the rockery for overturning can be behind the outer edge and still be within the required safety factor. If the required minimum thickness of rockery is to prevent overturning, then a rock should be placed that is in contact at or near the outer edge, or a thicker rock should be placed. HEMPHILL FIGURE 47 EXAMPLE ROCKERY HORIZONTAL DISTANCE ANGLE of TILT BACK - \\- IMPERVIOUS SOIL 2, FILTER FABRIC IS WRAPPED UNDER THE DRAINAGE PIPE, 3, NATURAL SOILS MUST HAVE BEARING CAPACITY TO SUPPORT ROCKERY SPIRO RESIDENCE 3. SLIDING BETWEEN ROCK and SOIL page 53 of 67 pages Tti''c is probably the most predominant method of failure of a rockery, therefore the proper nment of the rockery is critical. PASSIVE RESISTANCE to SLIDING The soils in front of the lower rocks will provide the passive forces that will help to resist the lateral movement of the rockery. The strength of the passive resisting soils result partially from the weight of the soil in front of the rockery, and from the cohesion and internal friction of those soils that determine their shearing strength. FRICTION RESISTANCE to SLIDING Also resisting the sliding of the rockery will be the friction forces between the bottom rock and the natural undisturbed soils, which is determined by the 'scratchiness'• of the soils and the weight of the rockery. 4. DISINTEGRATION of the ROCKS The disintegration of poor grade rocks is probably the second greatest cause of rockery failures, and because it is so obvious, is the greatest cause of litigation. The quality of rocks should be guaranteed by the quarry and the rockery contractor. w U 0 w U cc cn r cn Z 0 U cn ��z 'V Vl Lw a 00 ef' w m D C) LL LLJ U O O LLJ I— U O c~ z U LLJ m Q m O ry CL Cy— LLI U O z LO V) Li 0 N Ls� N D uj xz — Y z u x_ CL u w0 > L1. w u z a N N LLI LU N N Q CL LL U Q I— N cn LLJ CZ z 0 u LL 1 J 0 N u 0 SPIRO RESIDENCE DESIGN of ROCKERY page 54 of 67 pages The rockery will be designed in 1 foot vertical increments assuming a 1 foot wide slice. Figure 48 shows the design rockery versus the way that it will probably be constructed. DESIGN PARAMETERS for ROCKERY Figure 49 gives all the presumed or tested physical properties of the soils, and the properties of the rock, that were used by HEMPHILL to design the rockery. FIGURE 49 ROCKERY DESIGN PARAMETERS DESCRIPTION of PROJECT A. ROCKERY DESIGN for SPIRO FAMILY " B. PROJECT NAME . . . . SPIRO FAMILY HOUSE. C. PROJECT NUMBER . . . 1636 D. LOCATION OF SECTION ADJACENT to DRIVEWAY E.- DESIGN TRIAL NUMBER 1 .............. ....... ..... ........ --........... ... ''......... ... DESCRIPTION of ROCKERY -------------------------------------------------------------- A. SHAPE of SOIL BEHIND ROCKERY 1. SHAPE of SOIL ADJACENT to ROCKERY ANGLE of SLOPE VARIES from 0 to 45 degrees VERTICAL HEIGHT of SLOPE VARIES from 0 to 10 ft 2. GROUND SURFACE BEHIND ROCKERY is HORIZONTAL B. SURCHARGE LOADS BEHIND ROCKERY 1. POINT SURCHARGE LOADS BEHIND ROCKERY POINT NO. LOAD (LBS) DISTANCE (FT) ......... • ---------- ............. 1 1,000 2 2 1,000 8 2. NO UNIFORM SURCHARGE LOADS BEHIND ROCKERY .................................................... SOIL DESIGN PARAMETERS .............................................................. A. ACTIVE DRIVING SOILS a. UNIT WEIGHT . . . . . . . . . . . . . . n 120 PCf b. COHESION . . . . . . . . . . . . . . 0 PSI c. INTERNAL FRICTION . . . . . . . . . . 25 deg B. PASSIVE RESISTING SOILS a. UNIT WEIGHT . . . . . . . . . . . . . . . 110 PCf b. COHESION . . . . . . . . . . . . . . . . 200 Psi c. INTERNAL FRICTION . . . . . . . . . . 20 deg .............................................................. ROCKERY DESIGN PARAMETERS .................................................... VERTICAL HEIGHT of ROCKERY VARIES FROM 0 to 10 it TILT of ROCKERY from VERTICAL VARIES from 0 to 40 deg MINIMUM THICKNESS AT TOP . . . . . . . . . . . . 1.5 ft DENSITYof ROCK . . . . . . . . . . . . . . . . . . = 160 pcf % 14AXIMUM ALLOWABLE VOIDS . . . . . . . . . . . . 20 % FRICTION FACTOR for ROCK on ROCK . . . . . . . . . = 0.55 FRICTION FACTOR for ROCK on SOIL . . . . . . . . . = 0.40 FRICTION FACTOR for SOIL on ROCK . . . . . . . . . e 0.30 DESIGN SAFETY FACTOR . . . . . . . . . . . . . . . e 2.00 ............................................................ SPIRO RESIDENCE page 55 of 67 pages The parameters that were used to design the rockery are explained in the following paragraphs. a. LATERAL DRIVING FORCES The lateral soil forces used for design purposes were determined based on the use well compacted granular structural fill. The lateral forces on the rockery include the wheel loads from a heavy car or light truck. b. LATERAL RESISTING FORCES 1. FRICTIONAL RESISTANCE Frictional resistance to sliding between the undisturbed soils and the bottom of the rockery will be approximately 0.4 x the vertical weight of the rockery on the soil. 2. PASSIVE RESISTANCE The existing cohesive soils directly in front of the lower rock offer passive resistance to movement at the base of the rockery. The greater the depth of the lower rock or rocks below the final grade (KEY), the greater the passive resistance. The minimum value of passive lateral resistance in the undisturbed soils would be determined by the strength of the soils. The properties that determine the strength of the passive soils are 200 psf cohesion and 20 degrees internal friction. SAFETY FACTOR and INSPECTION The safety factor applied to a rockery design is directly related to the degree of expert inspection. A lower safety factor of approximately 1.7 might be acceptable for a full time inspection, but for small walls the inspection might be more costly than over -design. A safety factor of 2 might be acceptable for periodic inspections, where requirements for partial rebuilding of a rockery might be acceptable, or where the rockery can be slightly over -built beyond the plans to guarantee probable compliance. A safety factor of 2.5 might be acceptable for a single inspection after the wall has been completed, or where no inspection is anticipated. HEMPHILL applied a safety factor of 2.0 for the design of this rockery, because the rockery will be small, and because minimal inspection is anticipated. HEMPHILL Z 0 V cn Z 0 V 0 "WE c I Z 0 V / Z W 2 U 0 Im LU 0 LL ti 3 P M N �0 O •P_ 11 � O � II I M .f N N •O n 00 00 II x r _ 11 II Y O O O O N N O N O O N N \ II W M II Y • 0 0 0 0 0 0 •� N N N v It _ In, i O N OO N N P N r0 P M U Y 1 S O-- - N N N M M M J 11 C II n Y I N N M M N M M M N N an II U of S _ _ _ _ _ r 11 � r 3 O M un1 l9 O M P N J of _ _ � •• N N II r 11 O _ N N M J .f N N •O •O n II x U Y• O O O O N N O N O N O \ n W P. 11 Y• O O O O O O N N M •� II Z r O O M •O P N N 00 •� M •O II ti 11 > O •- �- _ •- N N N M M M u O 11 II U r N M N N N Yl N N N N M u x ----------- 1. - r 3 I O M Vn1M- I� O M IPA II i I d •O n s n n yyY11 r 0000lnoln ornoln N \ II Y 0 0 0 0 0__ N N M M N II I P � J •O 00 •-' I H II p r O e- � .. � •� N N N N M 11 11 r N to N N N N N Yl M Y1 11 UY N of x .- _ _ _ _ _ r• • of � I of o� �2i^ter r.N of n 0 •• N N M M M O J J N 00 n S • � II n Y O O O O Ul O N O N O O N •\ 11 ]W! • 0 0 0 0 0_ N N M M • M 11 1 11 2 O P 1 M VN n W O N In _ II 11 Y r N M N N N N N M N •O n n u r II Y I Ij O p N O N N h N ofOC i M N 41 II 7 • N N M M M M t- n 1, � N I II Y O O O M M O M O O O 'Al •- \ 11 1L 10 0 0 0 0_ !- N N N N � 11 11 Z O P O N M J •O 11M N 11 f 1 0 r 0 0__ .� � •� J d J 11 Y I M M Itl M M N In N P P P n u II s e- _ •-• •- d �t .f I of Y r 11 O N N N •O O^ m II A ^ N 11 1 n 0_ • �• N N N N N .f 1 •O •O 00 u {a I 000u+Inolnooln v+ r M 2 O O P O N IM y 100 1� O I O O O •� •� _ N N M M .f n u r � I.S. . .- .� .� •�-1 .p- M M .f d V a . NO 0Up1 pJ, P J IUI 7 rJi •AP 1� N M In Oo 1 • II O N N N N d Y M •O f� /r U S • � U M Y r 0 0 0 N 0 0 0 N N 0 0 N n O O O • N N II n 2 O m t0 P P P n •O .T M M IS 5 O O O O O N N N M J n o • n ii u Inlnlnu+lno ooPo.- • II H • 11 p� O N N d N J v v N n 3 M •O Ono NO P 0°mp• N ry M1y II I N M J •Oof 1� J n S fq3 n Y O O O N In In O O O I/1, M O /•• tl Y I 0 0 0 d 0 0 oy1ue! of I„III Y N N N N1 I Y• �•• •• J d �f 1-- n n I- pN� II Y r w• p~� U W 1 O N M •f N �O f� 00 P O I > S I O N O 2 Z 4 W m W yY O 2 S Y S z .�- < x s � oc i u � O < J OC ul 0 0 s 0 ZH O z 7 w xOOx aW W N W •csaz u w o x t. O Cr J J m W O Y It K S Z W W � O Y Z S W W VI rc �u Y •.- 1- of O yp° m �u I, H C w � W fff...777 r- U 2 F• x W v O s z Z u N Q w N 01 8 V 1_ O z o y Y J (Y 17 ► W J W M O 0 < Y U K Z ypY O E xGW K O o Y s U t1W00,1 W_ O Y W =K= O O w < O O Y0z 21 m IN/1 Y '1• Z °• x Z ° fW[ Y ``J 2 d r Y U x O W W OL O J O < J �jO F J W J 10 40 1- Z < O[ F W :1:18- n U n 11 of If O Z = � =1s-tiffs gi J SPIRO RESIDENCE page 56 of 67 pages DIMENSIONS of ROCKERY Figure 50 gives the required minimum dimensions for a 1 foot section of rockery, for various rockery heights, and for various angles of tilt. All the required minimum dimensions are calculated based on the same factor of safety, therefore all the rockery options are equally safe. EXPLANATION of "ROCKERY DIMENSIONS for CONSTRUCTION" Figure 50 shows the vertical height of the rockery in the left column under HEIGHT. The required dimensions of the rockery shown to the right of HEIGHT can be for a rockery of that total height, or can be for that portion of a higher rockery. The tilt of the rockery measured along the back of the rockery is shown at the top row in degrees, and in the second row in the ratio vertical distance to horizontal distance. The tilt back of the rockery is shown in 5 degree intervals ranging from 0 degrees (vertical) to 40 degrees. At each interval of height the required thickness of the rockery to resist sliding and overturning at that interval over the next rock down is shown under the column THCK for THICKNESS' of rockery. As shown in Figure 47 on page 53, titled °EXAMPLE ROCKERY', the thickness is measured from the front of the rockery to the rear. The dimension given under the OWN column is the minimum allowable distance measured from the front of the rockery to the pivot point of the rock to prevent overturning. The pivot point is the first point of contact between two rocks measured from the front of the rockery. If the OVTN parameter is 0, then the 2 rocks at that height must be in contact at the very front edge of the rockery, and the required rockery thickness was determined for overturning rather than sliding. If OWN is greater than 0, then the required minimum rockery thickness was determined based on sliding, and the pivot point can be less than the required thickness for sliding. If the value for OWN is greater than the thickness of the rockery, then the rocks are apparently leaning into the slope, and overturning is negative and is not a problem. The values shown under the column KEY, ' indicating the depth to key the bottom rock, is the required depth of the bottom rock or rocks to be placed below the ground surface to achieve resistance to sliding. The required key shown at each height is only for a rockery with that total height, otherwise the value has no meaning if the rockery has a greater height. The horizontal distance taken up by the rockery from the front of the bottom rock to the back of the top rock is shown under the column HD for 'horizontal distance'. That value will help to choose the rockery that will best fit into limited spaces. The total weight of the rockery for that particular height and angle of tilt back is shown under the column WR for weight rock'. That value can be used to help choose the cheapest rockery, and can also be used to estimate the cost of the rockery at that location. �_.�_ v .. _*' �__ _..._ _ _. ._ I � t„ I � I �_.,� SPIRO RESIDENCE page 57 of 67 pages QUALITY AND SHAPE OF ROCKS To prevent deterioration from weathering, only top quality rocks should be used. The rocks should be hard, sound, durable, and should be free from seams, cracks, and other defects tending to destroy resistance to weathering. NO GOOD! The rocks should have a density of approximately 165 pcf since that was the density used for the rockery design. If rocks of a different density are used, then the required dimensions shown on 'ROCKERY DIMENSIONS for CONSTRUCTION' must be adjusted in direct proportion to the change in density. The rockery should be redesigned to prevent any confusion. PLACEMENT of ROCKS NO GOOD!. Rocks should have fairly flat tops and bottoms to allow for adequate contact to resist overturning, and to allow for a relatively tight wall. Rocks should be placed so that the vertical seam between 2 adjacent rocks is not above or below the vertical seam for the upper and lower layers. In other words, as much as possible, each rock should overlap at least two different rocks below. Rock shapes should be chosen and placed so that no more than 20% of the wall face is voids. A GOOD! higher percentage of solid rock increases the required weight of rock needed to resist overturning and sliding. If a different void volume is placed, then the required rockery sizes must increase in direct proportion with the increase in voids so that the required rockery weights to resist sliding will C9be achieved. WORKMANSHIP for ROCKERY CONSTRUCTION Because of the angular and inconsistent shape of rocks that are available in the Seattle area, it is difficult to control the dimensions of a rockery. It is also difficult for workers to understand the complexities of a rockery, and the meaning of any deviations from the plans, since any plans for a rockery are extremely idealized. Therefore, even the most conscientious of workers could place rocks in a dangerous manner that would only be obvious to an expert. FILTER SYSTEM A properly constructed filter system behind the retaining wall is imperative to prevent the loss of structural fill behind the rockery resulting from seepage erosion from infiltrated rainfall or runoff. HF = 1I � � I, f�l II i IIII i.--�,—__._ "®"'a,_..=. I �' Ili ill � �� 1 ; ��, i;i �! �� I�I,I r. i_ ~'4 1 � I ; I � `r'rt I i-. SPIRO RESIDENCE page 58 of 67 pages As shown in 'EXAMPLE ROCKERY' on page 53, the first layer of the filter system behind the rockery should be composed of crushed rock that is tightly packed between the rocks and the natural soil to give the soil lateral stability. The crushed rock should be backed by either a filter soil or a filter fabric to prevent the infiltration of the soil into the voids of the crushed rock, depending on the gradation of the natural soils, and on the availability of suitable filter soils, and the ease of placement. Any other filter methods can be the option of the contractor, with the approval of HEMPHILL ROCKERY DRAINAGE The need for rockery drains, their locations, and their design, should be determined by HEMPHILL after the true groundwater conditions have been exposed at the time of construction. The required height of the drainage system will be dependent on the potential height of the seepage zone, which should be determined by HEMPHILL at the time of construction. All rockery drains must have a filter system to prevent the natural soils from being eroded into the drainage system, and to prevent the creation of voids adjacent to the drainage system. The preferred filter system is a filter fabric. If a soil filter is desired, then the backfill materials placed behind the rockery must be controlled to prevent the infiltration of the natural soils, but to not erode through the void spaces in the rockery. Generally, the cost of testing to determine the existing soil sizes, and the engineering to determine the proper backfill material, and the difficulty of obtaining the designed materials, and the difficulty of placing multiple filters, is not justified. Generally, perforated drain pipes should be located in a manner to lower water below the bottom of the rockery, and to prevent the potential undercutting of the rockery by erosion. The location of rockery drains will sometimes be dependent on the method of construction of the rockery, and the location of adjacent excavations. Rockery drains should be sloped to allow drainage without creating low spots where water will accumulate. HEMPHILL recommends a slope of at least 11/1 U. The size and type of perforated pipe should be determined by HEMPHILL based on the anticipated vertical loading, the quantity of water to be conducted, and the grain size of the adjacent drainage material. The perforated pipe should be connected to solid pipe after leaving the area to be drained. The solid pipe should not be connected to any other drainage systems before a catch basin that can overflow below the lowest elevation of the rockery drain. That will prevent another drainage system, such as a downspout, from clogging and backing up through the rockery drains. FIGURE 51 LOCATION of NEW INTERCEPTOR DRAIN _ �If,4DDlYd,4l� • dlp Nzp°lB%1y AD11 A SPIRO RESIDENCE page 59 of 67 pages The required drainage backfill will depend on the quantity of water to be intercepted, the required height of drawdown compared to the horizontal distance of the backfill trench, the grain sizes of the adjacent natural soils, and the type of filter system that is used. The figure 'EXAMPLE ROCKERY' shows a rockery drainage system. DRAINAGE EXISTING INTERCEPTOR DRAIN There presently exists on the site an interceptor drainage system that is located at the toe of the bench, that then conducts the intercepted water to a drainage system located alongside Meadowdale Road. NEW SUBSURFACE DRAINAGE The interceptor drain at the toe of the bench will be removed and relocated to the top of the excavated bench behind the proposed soldier pile wall. The new drain will be located as shown in Figure 51. Figure 52 on the next page shows the proposed interceptor drain system behind the soldier pile wall. The location of the drain is based on the assumption that the excavation for the new bench will be into the hard clay, and that any groundwater seepage will have been encountered behind the soldier pile wall. if the groundwater seepage zone has not been encountered as anticipated, then excavations should continue to the top of the hard clay. If necessary an interceptor trench can be conducted separately from the soldier pile drainage system. SITE SURFACE DRAINAGE To prevent erosion of downhill slopes, HEMPHILL recommends that stormwater runoff from adjacent sites, and stormwater from impervious areas on the site, including runoff from roof drains, should be intercepted and conducted to a stormwater drainage system approved by the building department authorities. Water from the parking area and driveway should be conducted to a catch basin designed to entrap oil and sift. Figure 53 on the next page shows the location of the proposed stormwater detention system that will collect surface water runoff and control the rate at which it enters the municipal system. The ground surface should be sloped away from the structure to prevent the accumulation of water adjacent to the grade beams that could then seep into the crawl space. FIGURE 52 SOLDIER PILE DRAINAGE STEEL BEAM LAGGING 12 CONCRETE PILE. -- 4" 0 'COMPACTED SOIL A, DRAINAGE BETWEEN PILES L" 1. EXCAVATE BETWEEN PILES A 4" SPACE BEHIND LAGGING FOR DRAINAGE. 2. PLACE FILTER FABFIC AGAINST EXCAVATED SOIL AND ON TOP OF CONCRETE PILE. 3. PLACE PERFORATED PIPE DIRECTLY ON FABRIC OVER CONCRETE PILE. 4. FILL SPACE WITH GRAVEL APPROVED BY HEMPHILL TO WITHIN V FROM FINAL GRADE. WRAP FILTER FABRIC OVER TOP OF GRAVEL. 5. FILL LAST 1' WITH SOIL AND COMPACT. B, DRAINAGE BEHIND PILES 1. EXCAVATE THIN SPACE BEHIND BEAM, WITH LARGER SPACE AT BOTTOM FOR PERFORATED PIPE, (IF HOLE STAYS OPEN, SPACE IS LARGER THAN SHOWN, AND CAN BE BACKFILLED WITH GRAVEL ON BEAM SIDE, OR SOIL ON OPPOSITE SITE OF FABRIC, 2. PLACE FABRIC BY SLIDING DOWN FROM TOP, OR THROUGH FROM SIDE. 3. PLACE.PERFORATED PIPE BY SLIDING FROM SIDE, OR DOWN FROM TOP 1F HOLE HAS STAYED OPEN. C. ALTERNATIVES THERE ARE MANY ALTERNATIVES AT THE OPTION OF THE CONTRACTOR WITH THE APPROVAL OF HEMPHILL. SPIRO RESIDENCE L page W of 67 pages FIGURE 53 PROPOSED STORMWATER DETENTION ; O f I �O°\ \ rrairt roe• ( � �, •cA� � �� 00, 01 \ O" ZD1--- ��i "=n 4p Fir t c�51��-� �•.r;�� ..o� `�ti`',l ��u nr Uz �^ I —4w le —/ y_•_ _ ,�• . / 2 11 ; 1 _ � f � � � te►cC ~ � � �• + Ili (_-_-.L- _ _ �� �__- -- -•r"t /�,\�i � �� x � - "�� �� �; �`-�s'� fir • L]b ( on rIf g; � s /44. 4/V HEMPHILL SPIRO RESIDENCE page 61 of 67 pages DRAINAGE of GARAGE SLAB BASE COURSE The garage slab base course or capillary break should be open to drainage to prevent the accumulation of trapped water within the garage grade beams. As previously explained, the excavation under the garage should be sloped to the northwest at least 11101 to prevent any water from becoming trapped under the garage slab. To allow for the escape of any trapped water, the drainage can be openings in the grade beam along the east side of the garage, or gravel filled trenches can be installed beneath the garage floor slab, that are then connected to an outside drain. The type and number of drains can be determined at the time of construction. The garage slab base course drain can be incorporated with the crawl space drain by allowing any seepage to flow thru the grade beam between piles 4, 5, and 6 and into the crawl space. SPIRO RESIDENCE page 62 of 67 pages CRAWL SPACE DRAINAGE Standing water in a crawl space is generally not desirable, but it is not necessarily detrimental, unless contact with wood structural members causes rot, or high humidity seeps into the living areas. The most serious result of wet crawl spaces can be decay of the wood structural members. Literature describing the cause and prevention of wood decay is published in the U.S.D.A. Forest Service Research Paper FPL 190, and also in the U.S. Department of Agriculture Home and Garden. Bulletin No. 73. Local building codes include specifications similar to the recommendations presented by these publications for the prevention of decay. Wood decay is caused by fungi that can occur in several forms. The U.S. Department of Agriculture describes those fungi as brown rot, white rot, and several other less common forms. For decay to occur, spores of the fungus must be present, and to survive and propagate the spores need wood, water, oxygen, and an acceptable temperature, preferably between 50 and 90 degrees. Generally, most crawl spaces have all of the ingredients necessary to propagate the fungus. The literature published by the U.S. Department of Agriculture describes the prevention of decay as simply denying direct contact between water and the wood structural members. The direct contact can occur in 3 ways: 1. Wood structural members can be placed adjacent to damp soils, which is against all acceptable construction practices. 2. Water can rise in the crawl space to contact the wood structural members. 3. Warm, humid air can condense on colder surfaces adjacent to outside cold air, or adjacent to upper air conditioned floor systems. Short time wetting of wood structural members during temporary infrequent flooding conditions would not be damaging if the wood members could dry quickly and completely. If flooding occurs frequently, or if the wood members cannot dry quickly or completely, then the rising of water in crawl spaces can be controlled by gravity drainage placed below the level of the lowest wooden structural member. High humidity can be controlled by covering the damp soils with plastic, or the humidity can be removed by placing properly. sized. and located air vents to allow air circulation within the crawl space. Local building codes generally include specifications that require both plastic covering and properly designed air circulation. SPIRO RESIDENCE page 63 of 67 pages HEMPHILL recommends that the crawl space be covered with plastic, and that the proper ventilation be installed with care not to allow dead air spaces. THE PLASTIC COVERING SHOULD END AT THE FOUNDATION WALL AND SHOULD NOT BE PLACED UP THE FOUNDATION WALLS AND NOT IN CONTACT WITH THE SILL PLATES. HEMPHILL recommends that any water that seeps into the crawl space should be able to escape through a gravity drain that is placed within the crawl space adjacent to the lowest outside area that can accept the gravity drainage. The crawl space should have been excavated to slope down at least 6 inches, or 1' per 101, to the low side of the crawl space, as previously explained. A gravity drain can be a solid pipe that is placed under or through the grade beam, and that will conduct water to the recommended outlet. The crawl space drain, any footing drains, and the garage slab drain can all be combined and run into the interceptor drainage system, or they can be open to a lower ground surface, but they must not be connected with the surface runoff system unless there is an open catch basin at the connection that is below the level of the crawl space or any grade beam drains. If the outlet pipe is open to disperse the water onto the ground surface, then the pipe should be perforated for the length that is exposed at the end to allow any water to disperse, and should be capped to prevent the entrance of creatures into the crawl space. DRAINAGE for GRADE BEAMS The need for grade beam drainage systems, their locations, and their design, should be determined by HEMPHILL after the true groundwater conditions have been exposed at the time of construction. Since the grade beams will be formed on the crawl space surface, then any drainage system placed at that level would probably be useless, and any water would seep under the grade beams and into the crawl space. If the quantity of potential seepage water is low, then grade beam drains will not be required. If it is determined that water should be intercepted outside the crawl space, then drains should be placed in a trench outside the crawl space at least 6 inches lower than the grade beams, and sloped to flow, as previously recommended. Any grade beam drains can be combined with the crawl space drains and connected with the interceptor drainage system. DRAINAGE for RETAINING WALLS The retaining walls at the northeast corner of the house will require 'footing drains" to prevent hydrostatic pressures, and to prevent seepage through the walls. The required height of the foundation wall drainage system will be dependent on the potential height of the seepage zone, which should be determined by HEMPHILL at the time of construction based on the structural fill used, and the potential for water intrusion into the soils. �a� C!) z_ Zcn m J 7 o 0 �Z pZ Oa �_.. U J W M 2 M Rt Lsn uj LL W w m LU a OW mp W OZ 0D °0 CL to U O C� cc cr cc CL !�'I�(?1��(''��'� •'I I'' tL'�r+y" �� 'itFj�� �yII•"/'"�'1 �� '�IF/+`,}'1`1 r .a .t �����5/I;, `r+rt'S'+,,Tf51i���:�It,�trTit';l�i'�+'�+>l�`/G:s�,�cr���r�t t�;�,l,'�,.1,:•�,• �1.Irc�ir�,Z;�l�4,'!:�,,;5:i1'I+Slrrp{i�`;�y�:�:I,;i;%!��'';1•��'{ti:r:,, �.!iwG•��a�sS%�/' ��.9%��,�l��T?•'i��Y�i%�9���"•A%.'���I���i fj•t,j � � ;' { I 1r•��Sr ,.,nl III I I I � ' 1�`i� ;�:.�; :•,: � �'. W 0 z ' ';fats;;';:;;• LLJ oc a .11, CL a W J J U 17L LLJaww zwaa 2 aa,z� aLLI wWM 00>0 wa0cr. CL Im Q paCCrpQ0 cc uj = LLI w�U J 0 q _ UJ ILL �Om2W Ow-12C aa0>CW �0w�m za 00 N _J WN o° 00 __ �N LU CL z n• a zJ �O N 0 N w Q0 OWE CC a� N aw= LLa cc Q�z OZ �at0 zwzU a=0� OmU� 0 M wZ 0 wpQU °' woz azoc am0a Z = �a aLu amw0 �0Mm ...I=ccX acnF-w M ������t���ISJC•y'•I r, ' II�+Yii��1',�`/Jir'( I�!,5�<r�'lil�'�j;•. ''.�:�j. { I r,i.f!�,lu'pn>rr<t��;+;5 '',�(r l�Ir .!•I I ;'r„ },t,,r $F;r'!±'arll:,I 57 +�'l�(i+k.r•Sil� ,il,',�, ' . {' { I •i;t'`�:trr':'r Irlif:l., p+':i:':y;:�, ,,,'1''',1��; I I lir)I :;II'/,r''Iti+';� Id'r%,'ir,r• ! ( �5,1;�:'j'I ',�,, ' 1� � I I f,';'',1 tiv,fill;,(,h't'•'t�Y J54:�r!(1, )•'�''S�%li��(f,�+'+1,�'�!1.� }r•� r,• ,Y�:�rl:,.[If:r'r/.'t5�. (,.. �. rlt:, iltt,+ 1 II+ 5�! �'• �r -� in 0 LL o) �- U go o M w a aUw aau- :' a000 W U 2 o :f il::;«<;.5� gal, ;;,�;•,�r,... , o �� a' z a v cc o I.g Y0 �� zo N I, w ty 1 4,• m SPIRO RESIDENCE page 64 of 67 pages The retaining wall drainage system must have a filter system to prevent the natural soils from being eroded into the drainage system, and to prevent the creation of voids adjacent to the drainage system. The preferred filter system is a filter fabric.* Generally, the main purpose of the retaining wall drainage system will be to lower the groundwater adjacent to the wall to reduce the potential hydrostatic pressures against the wall. The drains might also be required to prevent groundwater from seeping through the wall to the interior living area, or under the wall to the crawl space area. . The retaining wall drainage system should be sloped to allow drainage without creating low spots where water will accumulate. The size and type of perforated pipe should be determined by HEMPHILL based on the anticipated vertical loading, the quantity of water to be conducted, and the grain size of the adjacent drainage material. The perforated pipe should -be connected to solid pipe after leaving the area to be drained, and the trench carrying the perforated and the solid pipe should not step up, otherwise any water running under the pipes will be trapped. The solid pipe should not be connected to any other drainage systems before a catch basin that can overflow below the lowest elevation of the perforated pipe. That will prevent another drainage system, such as a roof drain, from clogging and backing up through the retaining wall drains. DOWNSPOUTS OR RUNOFF DRAINS SHOULD NEVER BE CONNECTED TO RETAINING WALL DRAINS. The required drainage backfill will depend on the quantity of water, to be intercepted, the required height of.drawdown compared to the horizontal distance of the backfill trench, the grain sizes of the adjacent natural soils, and the type of filter system that is used. Figure 54 shows, 3 optional methods to intercept groundwater and conduct it away from the retaining foundation wall. The options should include that the drains should be located below the level of the interior crawl space. PAVING DESIGN of SUBBASE COURSE to RESIST CAPILLARY WATER Because of the potential high groundwater table at the site, and the silty nature of the soils above the groundwater, capillary water might exist within the soils directly beneath the base course for the driveway. To prevent the accumulation of capillary water within the frost zone of the base course; HEMPHILL recommends that, the combination of paved surface and base course be 1Z thick, and that the base course be composed of granular soils with a minimum size 1/4' aggregates. SPIRO RESIDENCE page 65 of 67 pages The granular base course should be open to drainage to prevent the entrapment of water. The granular base course will prevent the accumulation of capillary water which could freeze within 12 inches of the ground or roadway surface. The freezing process will create ice lenses which allow more capillary water to rise, because the frozen capillary water no longer acts as weight resisting the rise of the capillary water. The growing ice lenses will heave the paving. The heaving can be most damaging adjacent to the garage doors and the back porch. After the ice lenses thaw, the remaining pocket of water will soften the adjacent soils, and will also deflect under the pavement when wheel loads are applied, causing the paving to fail. If the base course is composed of aggregate with large void spaces, and is placed directly on the fine grained natural soils or structural fill, then a filter should be placed between the soils to prevent integration of the fine soils into the granular void spaces. The large aggregate would punch into the fine grained soils and settlement would occur. A filter can be a fabric, or it can be composed of soils designed by HEMPHILL in accordance with the adjacent aggregate sizes. The various aggregate sizes and filters can be determined by the contractor in accordance with the best and cheapest available materials, and with the approval of HEMPHILL 1 SPIRO RESIDENCE page 66 of 67 pages FUTURE STUDIES and RECOMMENDATIONS DESIGN REVIEW HEMPHILL has reviewed the final plans and specifications and determined that they are reasonably in accordance with the recommendations presented in the geotechnical report, assuming that HEMPHILL will conduct the recommended geotechnical inspections, and will present any necessary adjustments resulting from differences between presumed site conditions and actual site conditions, along with some options by the contractor, in accordance with actual conditions encountered at the time of construction. CONSTRUCTION INSPECTIONS and VERIFICATIONS 1. HEMPHILL should inspect the soils that are exposed in the borings for piles to verify that the required resisting soils and the allowable bearing soils have been encountered, and that there are no unexpected conditions that would require changes in pile design. 2. HEMPHILL should verify that the steel and concrete are properly placed in the borings to achieve the desired design conditions. 3. HEMPHILL should inspect, and if necessary conduct tests, to determine that any structural fill is composed of the proper soils, and that the required density has been achieved by the compaction process. 4. HEMPHILL should inspect the excavations to verify any suspected groundwater conditions, or to determine any unexpected groundwater conditions, or to determine any design changes. 5. HEMPHILL should determine that any perforated drain pipes are placed at the proper locations to achieve the required drainage, and that the intercepted groundwater is properly conducted from the site. 6. HEMPHILL should inspect all surface runoff drainage systems to determine that surface water is properly intercepted and conducted from the site, and that the runoff systems are not improperly tied to the subsurface system to cause the runoff system to back up into the subsurface system. 7. HEMPHILL should determine that any drainage backfill has the required permeability, and that properly designed and installed filters will protect the drainage system from clogging by fine grained soils that could be eroded into the drainage system by groundwater seepage. SPIRO RESIDENCE page 67 of 67 pages 8. HEMPHILL should determine that the garage floor slab, and the driveway paving, are underlain by a proper base course to protect against damage from freezing . 9. HEMPHILL should determine that the crawl space is properly drained and prepared to prevent high humidity and entrapment of water. 10. HEMPHILL should verify that any rockeries are properly constructed and drained. Dale C. Hemphill P. E. (9CL P rjj Registered Engineer No. 14777 State of Washington X, V S; 1 - i C:. J �'��� �,.s �-- _.. /; i..,.-- (, l i � /-_ -�. P H I L L CONSULTING ENGINEERS 0 ® o N w 0 m PROJECT NO. 1636 24 December, 1990 page 1 of 2 pages o a o o N � Q gay J z W MAR a W,Z` CLIENT David Spiro ° W 19405 89th Place West fta a o Q Edmonds, Washington 98020 o z N a i o REFERENCE: Proposed house located at 15631 75th Place West. Meadowdale 0 0 a SUBJECT Addendum to geotechnical report W W 0 N a INTRODUCTION Q D F N o ; Q < cU J This letter is an addendum to the report titled °Geotechnical Engineering for the Proposed Spiro 0 Z w Residence" by HEMPHILL CONSULTING ENGINEERS, and dated 10 December 1990. � CEo w The purpose of this addendum is to present a statement of risk based on City of Edmonds standards, N with an interpretation by HEMPHILL. 0 • 0 W STATEMENT z o - W U o 6 z Z PROBABILITY z - o W z Z Based on the City of Edmonds Landslide Hazard Map, within the next 25 years the site of the proposed Y o Spiro residence has a 2% probability of encroachment of slide debris from the rear slope, and a 25% 3 ¢ Q probability of a slump slide occurring downhill from the proposed house. QZ . w Probability statistics are not very accurate because they are based on such variables are seismic activity, w o 3 rainstorms, snow melts, and other natural events that cannot be predicted with any reasonable s accuracy. The actual cause of landslides can include changes or removal of vegetation, broken or leaking pipes, uncontrolled stormwater runoff erosion, stupidity of man, etc etc that can have an effect W on the physical properties of the potential sliding soils. z ° 0 W RISK of FAILURE W a W Q U. z a m HEMPHILL concludes that if the project is constructed in accordance with the plans, the specifications, J and the geotechnical report, and in accordance with recommendations by HEMPHILL at the time of w w z U Z construction, then: oj w a. the risk of major structural damage to the proposed house and garage is negligible because of z the support of the lateral resisting piles. Q W J N 0 0 921 1OJT" AVENUE S. E. a BELLEVUE, WA. 96004 ® 453 4760 r PROJECT NO. 1636 24 December, 1990 page 2 of 2 pages b. the risk of damage to the site is reduced because of the soil pinning action by the piles, reduction of driving soils by excavating a portion of the rear bench, and reduction of groundwater by placing improved interceptor drainage, and by intercepting stormwater runoff from impervious surfaces. C. the risk of damage during construction to adjacent sites to the north and south is minimal because no excavating will occur adjacent to those properties, and the property to the east will be supported by soldier pile walls placed before excavating commences. d. the risk of damage to adjacent properties after construction will be improved because of support by permanent soldier pile walls, and because of the influence of the improved site. CONCLUSIONS HEMPHILL has presented recommendations and designs based on the assumption that the site is potentially unstable at any time as the result of unusual natural phenomena. The stability of the site will be improved to minimize damage to the driveway, utilities, decks, and landscaped areas. The house and garage will be structurally supported by piles placed into stable soils to eliminate the potential for major structural damage. The stability of adjacent properties will be protected during construction, and will be improved after construction because of the influence of the improved site stability. Dale C. Hemphill P. E. cod PL-0.0 Registered Engineer No. 14777 State of Washington H E M I LL CONSULTING ENGINEERS 0 0 0 (0 w p (n z ° Q 0 r 0 H > W ~ > N z W m - > W z N J W 0 z � d d (N 0 0 ® e (n w 0 N W N 0 O w Q d o in O > z d W 7 z aw E 0 0 cn 0 0 0 z w 0 w U F W W U) z a a z z z - o w z z Y 0 W. CE 0 U a 3 a r � (n W ¢ z a W U 3 a 0 • UN 0 z o W CE a LL w ¢ (a z o m z X. W W 0 4 � Cl w z 7 0LL N ((n 0 0 PROJECT NO. 1636 6 March 1991 CLIENT David Spiro 19405 89th Place West Edmonds, Washington 98020 REFERENCE: Proposed Spiro house SUBJECT Response to geotechnical review INTRODUCTION page 1 of 6 pages .. LwyY7Iri7�^n The purpose of this report is to present corrections to, or clarify, the geotechnical report titled 'Geotechnical Engineering for the Proposed Spiro Residence' dated 10 December 1990, by HEMPHILL CONSULTING ENGINEERS, in response to a geotechnical review by LANDAU ASSOCIATES, INCORPORATED. The geotechnical report, and the review, are in accordance with requirements by the City of Edmonds for proposed construction within the Meadowdale portion of Edmonds. During a conversation with William Evans of Landau Associates, HEMPHILL became aware that some information that was either obvious to HEMPHILL because of familiarity with the project, or that HEMPHILL considered to be insignificant, was not clearly presented in the geotechnical report. Also it was determined that it would be necessary for LANDAU ASSOCIATES to have a better understanding of some decisions that would be,determined at the time of construction. Those decisions would be made by HEMPHILL but it would be necessary for the City of Edmonds to require that those investigations and decisions be made by HEMPHILL in accordance with recommendations presented by HEMPHILL on the last 2 pages of the geotechnical report. HEMPHILL SUBMITTED a supplemental letter DATED 24 December 1990 that presented a statement of risk in accordance with City of Edmonds standards This response is presented in the numerical order of the questions and comments presented in the LANDAU review dated February 12, 1991. RESPONSE 1. Historical information is being presented by David Spiro. HEMPHILL briefly referred to the history of the site on page 9 of the geotechnical report with the statement 'The largest recorded slide occurred in 1945 when large movements occurred in this gully.....'. This gully includes the site and all downhill property. Although the slide would have improved the stability of the site, along with the removal of septic systems, HEMPHILL recommended construction procedures and foundations based on the potential of instability at the site regardless of the present stability. 921 102T" AVENUE S. E. a BELLEVUE, WA. 9B004 a 453 4760 PROJECT NO. 1636 6 March 1991 page 2 of 6 pages 2. The existing interceptor drain has been monitored on numerous occasions during different seasons and rainfall conditions. Flow was never observed from the portion of the interceptor drain south of the outlet pipe shown on Figure 16 on page 15. The portion of the interceptor, drain north of the outlet pipe, which is located on the adjacent property to the north, has always had flow. The interceptor drains at this site were installed without any recommendations or inspections by a geotechnical engineer. HEMPHILL has concluded that the portion of the interceptor pipe on this site was placed above the sand/clay intersection. The top of the clay is lower at this site either because the site slid in the past, or because the site was a drainage channel, that then was filled with beach deposits. The top of the clay is higher on the site to the north. If the water is in fact moving on top of the clay, then the water cannot be feasibly intercepted at the present location of the interceptor pipe, or to the west. The top of the clay is more easily intercepted closer to the exposed clay at the east side of the site. Whether the groundwater is intercepted or not will not change downslope conditions since the present interceptor pipe is not functioning. If the groundwater can be intercepted easily at the time of construction then near surface conditions will be improved. If the groundwater is too deep to intercept, as it apparently is now at the location of the interceptor pipe, then intercepting the deeper water is not necessary. Figure 16 on page 15 shows the present location of the interceptor drain. Figure 51 on page 59 shows the proposed location of the new interceptor drain. The existing non functioning drain will be disconnected from the outlet pipe and abandoned. 3. The boring logs presented in the geotechnical report show that the fine sands that overly the hard clayey silt exist in a wet condition, which indicates near saturation to depths of 15 to 20 feet. The inference is that groundwater exists above the 'top of clay' as described in the geotechnical report. The groundwater blends from surface infiltration to capillary water to free groundwater. Site stability studies and the design of lateral resisting piles were based on conservative soil values, on the depths of the poor standard penetration values, wet soil conditions, and top of hard clay, resulting in a conservative line of stability of 1 vertical to 4 horizontal shown in Figure 23 on page 26. HEMPHILL assumed that everything below that line will be stable. Although the line of stability ranges from 4 to 12 feet below the existing ground surface, HEMPHILL designed piles based on the potential for all the fine sands to slide, and for the hard clay to provide lateral resistance for the piles. The piles were designed to resist 17 feet of potentially unstable soils. Since the piles are designed to resist all the soils that are wet, and since future drainage at the site will decrease surface infiltration and will possibly improve groundwater and will decrease driving soils, then downhill stability will be improved regardless of any existing groundwater conditions. PROJECT NO. 1636 6 March 1991 page 3 of 6 pages The 30 degree dip in the recovered sample is insignificant since it is 32 feet below the line of stability and is within hard clay that had penetrometer values in excess of 10,000 psf. The statement that the contact between the Esperance Sand and the Whidbey Clay was observed at 150 feet is an error. The contact was observed south of the property at elevation 250. That contact is significantly east of the site and above a large drainage system that was installed west of 164th Street SW. 4. More accurate topographic data has been presented on a revised topographic plan. There was some confusion because of the obvious differences in the topographic plan elevations and the elevations of proposed portions of the structure and the soldier pile wall. The true conditions were obvious during preliminary site visits when designs were discussed, and the topographic differences in the plans were ignored, One location for concern was what appeared to be the south slope being supported by the frame of the structure, but the view from the west in Figure 6 on page 6 shows that the portion of the house that appears to cut into the slope in the plan view is actually the second floor, and the first floor is located 10 feet inside that location. The south slope will be excavated to create a dog run, and the cut will be supported by a low concrete wall. 5. Structural calculations have been submitted to the Edmonds Building Department and have been accepted by Whitley Jacobson Engineers, 6. The project plans have been revised to show the required pile data for construction purposes. The 30 degree dip in the recovered sample is insignificant since it is 32 feet below the line of stability and is within hard clay that had penetrometer values in excess of 10,000 psf. The cause of the dipping could be natural or a chunk that collapsed into the boring, but regardless of the reason for the sample, because of the depth below the line of stability, and the strength of the adjacent soils, the effects are insignificant and not worth extra costs to pursue. The method used to design the piles is based on the procedures presented originally by Brohms in 1968. The beam on elastic foundation method was a forerunner of the Brohms method, which began with the design of the deflection of railroad tracks by Timoshenko in the 1800's. The method used to design the lateral resisting piles includes the relative stiffness of the pile in the calculations, therefore the deflection of the shorter piles does not return to zero, as shown in Figure 37 on page 45 where the bottom of the 25.7 foot pile has a deflection of-0.217, and the bottom of the 38.8 foot pile is strained to zero deflection. A plot of the deflections shown in Figure 37 will show the deflections of the shorter piles to be nearly a straight line, while the longer piles bend significantly by comparison. The pile deflections are not independent of the soil strains. The soil and the pile must work together as a unit. Adding an extra length to the bottom of the pile changes the deflections throughout the system showing the influence of the soil beam combination. PROJECT NO. 1636 6 March 1991 page 4 of 6 pages Over -consolidated soils do not have a changing rate modulus, but the method uses an adjustment to change a constant rate soil to an equivalent changing rate soil. The method of applying active pressures against a pile are not appropriate because the stronger the soil the lower the active pressure, which is directly opposite to what actually happens. The stronger the soil the greater the pressure against the pile. The design of the slide forces against a pile are similar to the method of designing a rivet. Assuming that the top of the slide is not near the pile, and that the slide actually moves without hanging up (which is the worst condition that can occur), then the stronger the soils the greater the drag on the pile. If the proper soil parameters (cohesion and friction) are used, then the stronger the soil the greater the drag around the pile. If active pressures are used then the stronger the soil the lower the pressures against the pile. The calculations shown in Figure 37 on page 45 show the deflections, bending moments, and shear for various depths of placement of the same pile. HEMPHILL usually places piles at depths into over -consolidated soils at least the depth of potential slide soils, depending on the relative strengths of the driving and resisting soils. The recommended depths of piles are described in Figure 32 on page 40; therefore the shorter piles will not be used. The final depths will be determined at the time of construction as the true conditions are revealed for each pile. 7. The soldier pile wall is designed to support a horizontal compacted backfill and some minor slough debris. The hard Whidbey Clay will not apply pressure against the wall as a cohesionless soil would, therefore the potential for a slope failure is not considered in the design, and the slope of the Whidbey Clay is ignored in determining the lateral forces on the wall. The transitions for the ends of the wall have been included in the revised drawings. The statement that the spacings will be determined after the excavations have been completed is in error. The statement should read that the spacings will be determined after the proposed depth of excavations have been determined, or if the wall is moved into or away from the slope at the time of construction because of conditions, then the height of the wall will change, which will also change the spans, as shown in Figure 44 on page 50. 8. After careful review of the areas to be excavated, we have determined that the amount to be excavated for the construction of this project are accurate. The detention system is considered a utility and therefore not included in the calculations in accordance with Edmonds building code. The grade beams will be placed at or near grade, requiring little or no excavation. The total excavating will not exceed 500 yards. 9. The placement of fill along the west side of the site will be much less than the volume to be excavated and will have no detrimental effect on the stability of the site, ,especially considering the other improvements that increase the site stability far more than any decrease from the fill. PROJECT NO. 1636 6 March 1991 page 5 of 6 pages To resist lateral loads the piles are far overdesigned for vertical support and are capable of supporting loads of 80,000 pounds using conservative values of 6000 psf end bearing and 1000 psf side friction within the Whidbey Clay. Assuming a heavy equivalent pressure of 50 pcf and a high friction factor of 0.5, the greatest downward drag on the piles would be 13,000 pounds. That assumes full mobilization along the entire length of the upper sandy soils. - 10. The drawings have been changed to show the rockery in accordance with recommendations by HEMPHILL. The standard detail by the City of Edmonds will allow a rockery to be build that will fail if build to the worst allowable conditions rocks are cubic shaped. 11. Slides in Whidbey Clay and Lawton Clay are generally the result of shallow surface slides which result from the weakening of the upper 2 to 3 feet of soils due to weathering (wetting and drying, freezing and thawing, root action, direct rainfalo. The debris slide is generally local and does not include a large area. The more dangerous slides are flow slides resulting from complete saturation of loose soils. There is no evidence that flow slides have ever occurred in the vicinity of the site. Any loose soils observed at the base of the slopes in the general vicinity are the result of 'slope wash' which generally occurs in small quantities at a time. The potential for a larger surface slide is remote, and there is a buffer zone that will protect the house if such a slide should occur. 12. Most of the east slope that will be within 20 feet of the proposed soldier pile wall is less than 30 degrees. There was no mention in the geotechnical report of an angle of repose for the east slope. The undisturbed Whidbey Clay can stand vertically for many feet, and the slough debris can stand at angles of 1 V : 1.5H if protected by vegetation. The south portion of the existing slope is fairly stable at the bottom because it is approximately the angle of repose of the slough debris. If debris should slide over the soldier pile wall it will lie between the wall and the house. There is not requirement that the debris be removed, but the owner should be aware that there is the remote potential for debris. 13. Typical drainage plans have been added to the design drawings, but final decisions for drainage should be determined at the time of construction, and the contractor should be aware that the drainage shown on the drawings are not final. 14. Agreed! 15. A. The dates used by HEMPHILL were stamped on photographs of the large very damaging slide in the general area. H E I�/I P I-4 I L L PROJECT NO. 1636 6 March 1991 page 6 of 6 pages B. There is no such thing as a specific blow count versus consistency. The standard penetration test (SPT) can be very misleading if not used with judgment, provided that it is accurate. If a fairly undisturbed sample is recovered, then a visual examination is more accurate that the SPT. The SPT varies with grain size, plasticity, and water content. Other factors are height of hammer, condition of spoon, side friction, pounding on chunks of rock or gravel,; slumping of the hole and pounding into the debris, missed blow counts during mental lapses, you name it, I've seen it. The consistencies recorded on the boring logs were based on visual examinations of the recovered samples. The boring logs also show the results of penetration tests conducted on the samples. C. Figure 29 is a standard figure used by HEMPHILL and the 90% was inadvertently included. The intent, regardless of any given compaction, is that the grade beam should not settle enough during the curing process to be damaged or to make the placement of the upper structure difficult. After curing the condition of the soils is insignificant. D. True! Those values are for light loads from deck and stair footings. The report also includes other important design recommendations for methods to attach decks to prevent damaging the main structure during settlement, and also includes criteria which will allow those footings to be jacked back into place in case of settlement. CONCLUSIONS Except for some disagreement of design criteria for the piles, and some clarifications of poor or misleading descriptions or drawings in the report and project plans, HEMPHILL agrees that most of the comments by LANDAU ASSOCIATES were appropriate, and the responses in this report attempt to clarify the geotechnical report and project plans, or to present any omissions. Dal C. Hemphill a7 Registered Engineer No. 14777 State of Washington e� HE p j, WAS t o� ',r Blietag6•,.•\�4. a - 4 CONSULTING ENGINEERS 0 0 0 U) W 0 N c 0 h L7 ti N h � } W > N J Z > m z W _ o J W W (n 0 z J Q Q (n J 0 0 0 0 W 0 W N N 0 W � a 0 U > Z Q w a � W 0 0 (n o a o Z C) W W U D W W N Z (L 6 Z Z Z o w 0 w Y 0 U 3 Q ¢ I h ¢ cUJ 0 a w U ® o 0 fl) _z o o W ¢LU Q LL W ¢ z 0 m J Z X J W W Z u Z 0 a a j7 o J OLL N (all e o a PROJECT NO. 1636 30 April 1991 page 1 of 3 pages CLIENT David Spiro 19405 89th Place West Edmonds, Washington 98020 REFERENCE : Proposed Spiro House SUBJECT Response to geotechnical review r' INTRODUCTION The purpose of this letter is to respond to the LANDAU ASSOCIATES letter of 19 April 1991, which was a response to the HEMPHILL letter dated 6 March 1991 which was a response to the geotechnical review. Each response is numbered in the same order as the LANDAU letter. RESPONSE 2. The LANDAU response apparently did not understand my explanation, which might have created confusion be referring to the north stub of the interceptor drainage system as being on the adjacent property. There was confusion about the location of the north property line, therefore the north stub might be on the Spiro property. Anyhow there is a north stub and, -a south stub, as shown on Figure 1. Since water only flows into the catch basin from the north stub, then the south stub is apparently above the groundwater level, or there is no groundwater along the south stub. HEMPHILL assumes that the top figure in Figure 1 is probably accurate. Removing the south stub will not change groundwater conditions on downhill properties if there is no water now being intercepted. ' The new drainage system to be located behind the soldier pile wall shown in SECTION AA of Figure 1 might intercept the groundwater the south stub is presently missing.if the GWL is located as shown by the long dash. if so, then downhill groundwater conditions will be improved. If not, as shown in the lower GWL shown by the short dash, then nothing changes. The new drainage system also will be placed in a manner to intercept the same water that the north stub now intercepts, but to assure that the present groundwater being intercepted continues to be intercepted, the north'stub will remain in place whether or not the new drainage system picks up the same water. 921 109TH AVENUE S. E. ® BELLEVUE, WA. 9BOO4 ® 453 4760 PROJECT NO. 1636 30 April 1991 page 2 of 3 pages If necessary, adjustments will be made at the time of construction as the true drainage conditions are exposed. 4. Although LANDAU'S concern for precise topographic features is correct, HEMPHILL considers the concern an over reaction, since topographic accuracy is always questionable on nearly every small project. HEMPHILL considers that making field adjustments for inaccurate topo part of the normal procedures for a proper geotechnical inspection and verification process. Most designs are conducted for a range that could include those adjustments. If a condition goes beyond the anticipated range, then additional calculations will determine any necessary changes. 6. Many engineers use the method for pile design used by HEMPHILL, which was devised by the Navy and presented in their NAVFAV Manual DM-7, and is based on the method devised by Brohms, and generally accepted by the engineering profession. The method used by most engineers in the Seattle is antiquated, not based on proper engineering analysis, and in some cases inaccurate. The calculations presentee by HEMPHILL show the deflections. bending mcrnents, and shear for various depths of the piles. The bottoms of the shorter piles dig into the sides of the hoie, while the longer piles eventually are bent into alignment with the hole. Generally, the short piles allow for the possibility of rreap, and the long piles are not efficient. LANDAU might not have noticed that the drawings show that HEMPHILL did not choose the shorter piles. The individual piles are to be a minimum of 30' deep, the retaining wall piles are 25, deep, and the soldier piles evi!i be determined at the time: of construction, but will range between 7.5 and 11 feet deeo. 7. A test pit was conducted at the north end of the bench where the soldior rile wall will be located, and the soils described in the geotechnical report as Double Bluff is deeper at that location. Those soils are ovariain by approximately 2'feet of slope slough where the angle of the slope is less than 35 degrees. Any portion of the slope steeper than 35 degrees is hard Whidbey Clay overlain by weathered :soils. If those soils should slough, a minor amount will pile up behind the wall, and the rest will overtr,p the wall, providing a clean up situation for the owner, previously stated in the geotechnical report. Where the Double Bluff soils are encountered with the steeper rear slope, then the spacing of the piles will be reduced by 2 feet less than shown in Figure 44. Any additional dough loads were accounted for by increasing the pressure against the wall from 30 pcf to a very coriservative 50 pcf. The wall is not designed to support a deep seated slide from the slope, but to only replace the support of the existing toe which is to be excavated. 9. HEMPHILL does not understand the response by LANDAU. The previous explanation by HEMPHILL explains that the effects of the fill have been properly analyzed. The placement of fill over fill is not questionable practice unless there is some detrimental effect that was not anticipated. PROJECT NO. 1636 30 April 1991 page 3 of 3 pages 12. HEMPHILL is well aware of the steepness of the slopes along the east bench. The soldier pile wall has been designed to replace the effects of the removal of the toe. 13. HEMPHILL assumes that others have followed through on the requirements for adequate drawings. Dale C. Hemphill P. E. Registered Engineer No. 14777 State of Washington a Rx. a� Off. *stilt°S°..� `,�� HEtl .PHIL_Lo CONSULTING ENGINEERS w 0 U)Project No. 1636 a 0 u► � � a >N t W o J z 4 W W ? CLIENT U)0 J W o zz m i o REFERENCE W 0 7 N W w z N 0 0 W N F Q Q J o < > z a W D w Cr cc 0 0 N a a o z O w W U W Wa N z z z o W o W Y. H 1- N W Q 0 a W U 3 a a a m 0 z 0 W a tL w a o z 0 m ii a z X J W W z U z Q N a z z J tL (1 tl01 a O a SUBJECT 30 July 1991 page 1 of 3 pages AUG 2 71991; David & Jody Spiro 19405 89th Place West Edmonds, Washington 98020 Property located at 15631 75th Place W, Edmonds Edmonds Permit No. I?,? Geotechnical inspections INTRODUCTION The purpose of this report is to present the results of geotechnical inspection conducted by Dale Hemphill of HEMPHILL CONSULTING ENGINEERS (HEMPHILL) on the proposed Spiro residence located at 15631 75th Place West, Edmonds. The geotechnical inspection was conducted at the request of David & Jody Spiro, in accordance with recommendations by HEMPHILL, and with requirements established by the City of Edmonds Building Department. The purpose of the geotechnical inspection, was to verify that the piles had been located in tho required depth of resisting soils, and that the piles were properly placed. At the request of the Building Department, HEMPHILL also observed the steel in the reinforced concrete INSPECTION HEMPHILL conducted penetration tests, probing, and visual investigations within the borings for the piles, and verified that the required depths of resisting soils had been penetrated, and that the steel and concrete were properly placed. Figure 32 on the next page is a copy of Figure 32 from the geotechnical report, and as shown on the construction plans, and shows the locations and identification numbers for the piles. Figure 2 on the next page lists the installation data for the piles. 921 109TH AVENUE S. E. a BELLEVUE, WA. 913004 a 453 4760 Project No. 1636 30 July 1991 page 2 of 3 pages FIGURE 2 INSTALLATION DATA for PILES PILE PILE PILE DEPTH DEPTH NO DEPTH STICK to to UP HARD WET DESCRIPTIONS ---- ------------------------- 2 30 0 AUGER CAST 3 19 11 AUGER CAST 4 30 0 AUGER CAST 5 30 0 CLEA1 OPEN HOLE 6 28 2 CLEAN OPEN HOLE 7 27. 13 CLEAN OPEN HOLE 8 29 11 10 SEEPING 9 30 0 10 SEEPING 10, 30 0 CLEAN OPEN HOLE 11 28 12 CLEAN OPEN HOLE 12 30 0 10 SEEPING 13 30 0 CLEAN OPEN HOLE 14 30 0 CLEAN OPEN HOLE 15 30 0 CLEAN OPEN HOLE 16 26 14 CLEAN OPEN HOLE 17 28 12 AUGER CAST 18 30 U- 14 CLEAN OPEN HOLE 19 30 0 14 7 7 20 30 0 14 7 21 30 0 22 30 0 AUGER CAST 23 30 0 CLEAN OPEN HOLE 24 30 0 AUGER.CAST 25 30 0 7 CAVED; FILLED TO 31; AUGER CAST 26 30 0 CLEALN OPEN HOLE 27 30 0 CLEAN OPEN HOLE 28 30 0 10 10 SQUEEZED I.N AT 81; POURED QUICKLY SAND TO 101; SQUEEZED IN TO 101; PUSHED LAST 4' PILE PILE PILE PILE NO DEPTH STICK SPACE UP DESCRIPTIONS 29 11.0 9.0 Entire depth drilled into dense sand 7.5 30 11.5 8.5 rr 8.0 n 31 12.5 7.5 rr 8.0 n 32 13.0 7.0 rr 7.5 n 33 13.0 7.0 n 6.3 rr 34 13.0 7.0 rr 6.0 n 35 12.5 7.5 n 6.2 rr 36 12.0 8.0 u 5.5 n 37 10.0 10.0 rr rr K A r'l Project No. 1636 30 July 1991 page 3 of 3 pages Except for Pile 3, all the piles were placed to the depths as designed. Pile 3 encountered an. obstruction, but because of the soil conditions, the tie to other piles, and because of the location of the pile, HEMPHILL determined that achieving the design depth was not necessary. HEMPHILL inspected reinforcing steel in the grade beams, floor slab, and foundation wall and determined that the steel was placed in accordance with the plans. CONCLUSIONS HEMPHILL concludes that the piles and grade beams, and the reinforced concrete, were placed in accordance with the 'plans, or with recommendations by HEMPHILL at the time of construction. aC .. Hem hill P. E. Registered Engineer No..14777 State of Washington �E C• NE�1p;'�, W a t �Q� RoQ�a�e�.•" j,��� MAL H I L L. H E M P H I L L CONSULTING ENGINEERS U) w 0 La z e 0 Y N F W J Z W sa-> F W z N 0 J W UJ En a 0 Q 0 z v (!1 J 0 . . U) W 0 J N N w_ N C 0 Q 7 ~ N a Q � 0 (7 > Z .Q w L9 0 u7 • • • Z 0 w w U O w w Z n N Z z 0 W 0 W Y Cl UJ 0 0 3 r F N ul Q Z 4 w UO V) 0 z o W w a (a Z 0 m Z X w W 0 Q _Z d LL f' N 0 j ,W (N� J 0 ? 0 LL fn UI . • • PROJECT NO. 1636 6 March 1991 CLIENT David Spiro 19405 89th Place West Edmonds, Washington 98020 REFERENCE: Proposed Spiro house SUBJECT Response to geotechnical review INTRODUCTION page 1 of 6 pages RECEIVED MAR 1 2 1991 LANDAU ASSOCIATESM0. MAP EfL'VI.IT COUNTER The purpose of this report is to present corrections to, or clarify, the geotechnical report titled "Geotechnical Engineering for the Proposed Spiro Residence' dated 10 December 1990, by HEMPHILL CONSULTING ENGINEERS, in response to a geotechnical review by LANDAU ASSOCIATES, INCORPORATED. The geotechnical report, and the review, are in accordance with requirements by the City of Edmonds for proposed construction within the Meadowdale portion of Edmonds. During a conversation with William Evans of Landau Associates, HEMPHILL became aware that some information that was either obvious to HEMPHILL because of familiarity with the project, or that HEMPHILL considered to be insignificant, was not clearly presented in the geotechnical repot. Also it was determined that it would be necessary for LANDAU ASSOCIATES to have a better understanding of some decisions that would be determined at the time of construction. Those decisions would be made by HEMPHILL but it would be necessary for the City of Edmonds to require that those investigations and decisions be made by HEMPHILL in accordance with recommendations presented by HEMPHILL on the last 2 pages of the geotechnical report. HEMPHILL SUBMITTED a supplemental letter DATED 24 December. 1990 that presented a statement of risk in accordance with City of Edmonds standards This response is presented in the numerical order of the questions and comments presented in the LANDAU review dated February 12, 1991. RESPONSE 1. Historical information is being presented by David Spiro. HEMPHILL briefly referred to the history of the site on page 9 of the geotechnical report with the statement "The largest recorded slide occurred in 1945 when large movements occurred in this gully ..... 3. This gully includes the site and all downhill property. Although the slide would have improved the stability of the site, along with the removal of septic systems, HEMPHILL recommended construction procedures and foundations based on the potential of instability at the site regardless of the present stability. 921 TOOT" AVENUE S. E. • BELLEVUE, WA. 9e004 • 453 4760 PROJECT NO. 1636 6 March 1991 page 2 of 6 pages 2. The existing interceptor drain has been monitored on numerous occasions during different seasons and rainfall conditions. Flow was never observed from the portion of the interceptor drain south of the outlet pipe shown on Figure 16 on page 15. The portion of the interceptor drain north of the outlet pipe, which is located on the adjacent property to the north, has always had flow. The interceptor drains at this site were installed without any recommendations or inspections by a geotechnical engineer. HEMPHILL has concluded that the portion of the interceptor pipe on this site was placed above the sand/clay intersection. The top of the clay is lower at this site either because the site slid in the past, or because the site was a drainage channel, that then was filled with beach deposits. The top of the clay is higher on the site to the north. If the water is in fact moving on top of the clay, then the water cannot be feasibly intercepted at the present location of the interceptor pipe, or to the west. The top of the clay is more easily intercepted closer to the exposed clay at the east side of the site. Whether the groundwater is intercepted or not will not change downslope conditions since the present interceptor pipe is not functioning. If the groundwater can be intercepted easily at the time of construction then near surface conditions will be improved. If the groundwater is too deep to intercept, as it apparently is now at the location of the interceptor pipe, then intercepting the deeper water is not necessary. Figure 16 on page 15 shows the present location of the interceptor drain. Figure 51 on page 59 shows the proposed location of the new interceptor drain. The existing non functioning drain will be disconnected from the outlet pipe and abandoned. 3. The boring logs presented in the geotechnical report show that the fine sands that overly the hard clayey silt exist in a wet condition, which indicates near saturation to depths of 15 to 20 feet. The inference is that groundwater exists above the 'top of clay' as described in the geotechnical report. The groundwater blends from surface infiltration to capillary water to free groundwater. Site stability studies and the design of lateral resisting piles were based on conservative soil values, on the depths of the poor standard penetration values, wet soil conditions, and top of hard clay, resulting in a conservative line of stability of 1 vertical to 4 horizontal shown in Figure 23 on page 26. HEMPHILL assumed that everything below that line will be stable. Although the line of stability ranges from 4 to 12 feet below the existing ground surface, HEMPHILL designed piles based on the potential for all the fine sands to slide, and for the hard clay to provide lateral resistance for the piles. The piles were designed to resist 17 feet of potentially unstable soils. Since the piles are designed to resist all the soils that are wet, and since future drainage at the site will decrease surface infiltration and will possibly improve groundwater and will decrease driving soils, then downhill stability will be improved regardless of any existing groundwater conditions. H E M P H I LL. PROJECT NO. 1636 6 M arch 1991 page 3 of 6 pages The 30 degree dip in the recovered sample is insignificant since it is 32 feet below the line of stability and is within hard clay that had pe netrometer values in excess of 10,000 psf. The statement that the contact between the Esperance Sand and the Whidbey Clay was observed at 150 feet is an error. The contact was observed south of the property at elevation 250. That contact is significantly east of the site and above a large drainage system that was installed west of 164th Street SW. 4. More accurate topographic data has been presented on a revised topographic plan. There was some confusion because of the obvious differences in the topographic plan elevations and the elevations of proposed portions of the structure and the soldier pile wall. The true conditions were obvious during preliminary site visits when designs were discussed, and the topographic differences in the plans were ignored. One location for concern was what appeared to be the south slope being supported by the frame of the structure, but the view from the west in Figure 6 on page 6 shows that the portion of the house that appears to cut into the slope in the plan view is actually the second floor, and the first floor is located.10 feet inside that location. The south slope will be excavated to create a dog run, and the cut will be supported by a low concrete wall. 5. Structural calculations have been submitted to the Edmonds Building Department and have been accepted by Whitley Jacobson Engineers. 6. The project plans have been revised to show the required pile data for construction purposes. The 30 degree dip in the recovered sample is insignificant since it is 32 feet below the line of stability and is within hard clay that had penetrometer values in excess of 10,000 psf. The cause of the dipping could be natural or a chunk that collapsed into the' boring, but regardless of the reason for the sample, because of the depth below the line of stability, and the strength of the adjacent soils, the effects are insignificant and not worth extra costs to pursue. The method used to design the piles is based on the procedures presented originally by Brohms in 1968. The beam on elastic foundation method was a forerunner of the Brohms method, which began with the design of. the deflection of railroad tracks by Timoshenko in the 1800's. The method used to design the lateral resisting piles includes the relative stiffness of the pile in the calculations, therefore the deflection of the shorter piles does not return to zero, as shown in Figure 37 on page 45 where the bottom of the 25.7 foot pile has a deflection of-0.217, and the bottom of the 38.8 foot pile is strained to zero deflection. A plot of the deflections shown in Figure 37 will show the deflections of the shorter piles to be nearly a straight line, while the longer piles bend significantly by comparison. The pile deflections are not independent of the soil strains. The soil and the pile must work together as a unit. Adding an extra length to the bottom of the pile changes the deflections throughout the system showing the influence of the soil beam combination. HENS P N i o PROJECT NO. 1636 6 March 1991 page 4 of 6 pages Over -consolidated soils do not have a changing rate modulus, but the method uses an adjustment to change a constant rate soil to an equivalent changing rate soil. The method of applying active pressures against a pile are not appropriate because the stronger the soil the lower the active pressure, which is directly opposite to what actually happens. The stronger the soil the greater the pressure against the pile The design of the slide forces against a pile are similar to the method of designing a rivet. Assuming that the top of the slide is not near the pile, and that the slide actually moves without hanging up (which is the worst condition that can. occur), then the stronger the soils the greater the drag on the pile. If the proper soil parameters (cohesion and friction) are used, then the stronger the soil the greater the drag around the pile. If active pressures are used then the stronger the soil the lower the pressures against the pile. The calculations shown in Figure 37 on page 45 show the deflections, bending moments, and shear for various depths of placement of the same pile. HEMPHILL usually places piles at depths into over -consolidated soils at least the depth of potential slide soils, depending on the relative strengths of the driving and resisting soils. The recommended depths of piles are described in Figure 32 on page 40; therefore the shorter piles will not be used. The final depths will be determined at the time of construction as the true conditions are revealed for each pile. 7. The soldier pile wall is designed to support a horizontal compacted backfill and some minor slough debris. The hard Whidbey Clay will not apply pressure against the wall as a cohesionless soil would, therefore the potential for a slope failure is not considered in the design, and the slope of the Whidbey Clay is ignored in determining the lateral forces on the wall. The transitions for the ends of the wall have been included in the revised drawings. The statement that the spacings will be determined after the excavations have been completed is in error. The statement should read that the spacings will be determined after the proposed depth of excavations have been determined, or if the wall is moved into or away from the slope at the time of construction because of conditions, then the height of the wall will change, which will also change the spans, as shown in Figure 44 on page 50. 8. After careful review of the areas to be excavated, we have determined that the amount to be excavated for the construction of this project are accurate. The detention system is considered a utility and therefore not included in the calculations in accordance with Edmonds building code. The grade beams will be placed at or near grade, requiring little or no excavation. The total excavating will not exceed 500 yards. 9. The placement of fill along the west side of the site will be much less than the volume to be - excavated and will have no detrimental effect on the stability of the site, especially considering the other improvements that increase the site stability far more than any decrease from the fill. H E M P H I L L PROJECT NO. 1636 6 March 1991 page 5 of 6 pages To resist lateral loads the piles are far overdesigned for vertical support and are capable of supporting loads of 80,000 pounds using conservative values of 6000 psf end bearing and 1000 psf side friction within the Whidbey Clay. Assuming a heavy equivalent pressure of 50 pcf and a high friction factor of 0.5, the greatest downward drag on the piles would be 13,000 pounds. That assumes full mobilization along the entire length of the upper sandy soils. 10. The drawings have been changed to show the rockery in accordance with recommendations by HEMPHILL. The standard detail by the City of Edmonds will allow a rockery to be build that will fail if build to the worst allowable conditions rocks are cubic shaped. 11. Slides in Whidbey Clay and Lawton Clay are generally the result of shallow surface slides which result from the weakening of the upper 2 to 3 feet of soils due to weathering (wetting and drying, freezing and thawing, root action, direct rainfall). The debris slide is generally local and does not include a large area. The more dangerous slides are flow slides resulting from complete saturation of loose soils.' There is no evidence that flow slides have ever occurred in the vicinity of the site. Any loose soils observed at the base of the slopes in the. general vicinity are the result of 'slope wash' which generally occurs in small quantities at a time. The potential for a larger surface slide is remote, and there is a buffer zone that will protect the house if such a slide should occur. 12. Most of the east slope that will be within 20 feet of the proposed soldier pile wall is less than 30 degrees. There was no mention in the geotechnical report of an angle of repose for the east slope. The undisturbed Whidbey Clay can stand vertically for many feet, and the slough debris can stand at angles of 1 V : 1.5H if protected by vegetation. The south portion of the existing slope is fairly stable at the bottom because it is approximately the angle of repose of the slough debris. If debris should slide over the soldier pile wall it will lie between the wall and the house. There is not requirement that the debris be removed, but the owner should be aware that there is the remote potential for debris. 13. Typical drainage plans have been added to the design drawings, but final decisions for drainage should be determined at the time of construction, and the contractor should be aware that the drainage shown on the drawings are not final. 14. Agreed! 15. A. The dates used by HEMPHILL were stamped on photographs of the large very damag slide in the general area. -_i g - HEMPHILL PROJECT NO. 1636 6 March 1991 page 6 of 6 pages B. There is no such thing as a specific blow count versus consistency. The standard penetration test (SPT) can be very misleading if not used with judgment, provided that it is accurate. If a fairly undisturbed sample is recovered, then a visual examination is more accurate that the SPT. The SPT varies with grain size, plasticity, and water content. Other factors are height of hammer, condition of spoon, side friction, pounding on chunks of rock or gravel, slumping of the hole and pounding into the debris, missed blow counts during mental lapses, you name it, I've seen it. The consistencies recorded on the boring logs were based on visual examinations of the recovered samples. The boring logs also show the results of penetration tests conducted on the samples. C. Figure 29 is a standard figure used by HEMPHILL and the 90% was inadvertently included. The intent, regardless of any given compaction, is that the grade beam should not settle enough during the curing process to be damaged or to make the placement of the upper structure difficult. After curing the condition of the soils is insignificant. D. True! Those values are for light loads from deck and stair footings. The report also includes other important design recommendations for methods to attach decks to prevent damaging the main structure during settlement, and also includes criteria which will allow those footings to be jacked back into place in case of settlement. CONCLUSIONS Except for some disagreement of design criteria for the piles, and some clarifications of poor or misleading descriptions or drawings in the report and project plans, HEMPHILL agrees that most of the comments by LANDAU ASSOCIATES were appropriate, and the responses in this report attempt to clarify the geotechnical report and project plans, or to present any omissions. Dal C. Hemphill P. E. C_'eo Registered Engineer No. 14777 State of Washington w ��egiet�tr+� `�SZObAI•�`, HEMPHILL IvaOwdc(le VYd`Iy i�qe. Area D ;n✓IA�lifl.c hrizalr&'rlsk CITY OF CONSTRUCTION P RMITTN ICAT ON OWNER NAME/NAME OF BUSINESS DAVIQ atld '-70ANNF- 5PIPC) w MAILING ADDRESS o -771) 171 St 5tree { 5'Al CITY Ed rnond .� ZIP 9 8020 TELEPHONE NUMBER 778- 4051n NAME PAN I E L bAUGEN F ADDRESS . q'71�3 15f h A•ve . NE a CITY- 52ct tt I e ZIP �f8115 TELEPHONE NUMBER N 523- g2.03 NAME D�516N WORKS CoN5TkoCnoN ADDRESS 21 92n3 1511-" Ave. NE I CITY QQZ `�a.H�le U STATE LICENSE NUMBER) ZIP 981t5 TELEPHONE NUMBER 523-92v; .D.E51&WCV7 -NS Leqal Description of Property - include all easements NUMBER y7' !9,�103 JOB�JS/39 ADDRESSSUIT l/l% r Y e LEGAL DESC IPTION CHECK SUBDIVISION NO. LID NO. �` 2/d PUBLIC RIGHT OF WAY PER OFFICIAL STREET MAP. TESCP / APPROVED BY EXISTING !fKt--' REOUIRED DEDICATION f PROPOSED ��t RIGHT OF WAY CONSTRUCTION PERMIT REOUIRED)j STREET USE PERMIT REQUIRED ❑ SEE ENGINEERING MEMO DATED AEyIE" V ,A xV e ' SIGN AREA ENV, REVIEW ALLOWED PROPOSED COMPLETE E%EMPT VARIANCE OR CU N !o- orWT 2 U.5 E 3 0.73 N Lb53 W ao Fr TU CITE( 0 EOMON05 Foal aD SETBACKS — FEET Z / 6(Z FRONT ZS / SIDE ' 11 Tax Account Parcel No. 5133-( o-M5-D30- © NEW OADDIALTER R RESIDENTIAL .1:1 COMMERCIAL PLUMBING MECHANICAL ElREPAIR El APT. BLDG. SIGN ElDEMOLISH ® EXCAVATE FILLOR GRAOE� CAA REMODEL El GARAGET NCE FEL— x_FT) swim 1:1POOL WOOD STOVEI RETAINING WALL/ INSERT ROCKERY �) RENEWAL (TYPE OF USE, BUSINESS OR ACTIVITY) EXPLAIN: G NUMBER OF STORIES NUMBER OF DWEL g 2+a5ernent- UNITSLING I NATURE OF WORK TO BE DONE (ATTACH PLOT PLAN) PLANNING REVIEW BY I a HEI H� µWEAR 7 NA DATE 5-2 - (( ERAGE 3 fJJ 2 IL Serf ism O'►-63, WO fW4051 CHECKED Y TYPE OF CONSTRUCTION CODE HEIGHT SPECIAL INSPECTOR AREA OCCUPANCYR_ OCCUPANT kEUHIED GROUP LOAD YES 0 NO REMARKS PROGRESS INSPECTIONS PER UBC 305 w6 S�A� fi�tiu FINAL INSPECTION REOUIRED �/ SIyN y brE , it VALUATION FEE +D PLAN CHECK FEE ' i4s .aotr 8 �t1oRg ,EN BUILDING � 23 /�9 �,/ Q Pf Or NEAT A �45 PLUMBING �Cf' Plan Check ND. %� ;i MECHANICAL This Permit covers work to be done on private property ONLY, Any construction on the public domain (curls, sidewalks, driveways, marquees, etc.) will require separate permission. GRADwc/FILL 5 STATE SURCHARGE Ne $ii Permit Application: 180 Days Permit Limit: 1 Year • Provided Work is Started Within 180 Days UJ W 30 ar "Applicant, on behalf of his or her spouse, heirs, assigns and successors in interest, agrees to indemnify, defend and hold I harmless the City of Edmonds, Washington, its officials, employees, and agents from any and all claims for damages of whatever nature, arising directly or Indirectly from the issuance of this permit. Issuance of this permit shall not be deemed to modify,.waive or reduce any requirement of any city ordinance nor limit in any way the City's ability to enforce any ordinance provision." //y,4�t fix 7�co DIA�1l..1 1 [ /IILI� p i / /36 5 PLAN CHECK DEPOSIT 300 TOTAL AMOUNT DUE 5 ZZ43 I hereby acknowledge that I have read this application; that the Information given is correct; and that I am the owner, or the duly ATTENTION APPLICATION APPROVAL authorized agent of the owner. I agree to comply with city and THIS PERMIT state laws regulating construction; and in doing the work authoriz• AUTHORIZES This application is not a permit until ed thereby, no person will be employed in violation of the Labor ONLY THE signed by the Building Official or his Code of the State of Washington relating to Workmen's Compensa• WORK NOTED Deputy; and fees are paid, and receipt is ti n InSurence. INSPECTION acknowledged in space %ovided. SIGNAPRRE IOWNER OR A �ry �lL YLC �JI L✓C� DATE SIGNED 10"Z�I1 f1 () DEPARTMENT OFFICIAL' I 1TURE DAA Y CITY OF `f, EDMONDS ATTENTION CALL FOR 'RELEASED BY: / DATE INSPECTION IT IS UNLAWFUL TO USE OR OCCUPY A BUILDING OR STRUCTURE 771�3.ZO.Z UNTIL A FINAL INSPECTION HAS BEEN MADE AND APPROVAL OR ORIGINAL — File YELLOW — Inspector A CERTIFICATE OF OCCUPANCY HAS BEEN GRANTED. UBC ec %tJp 1 CHAPTER 3. PINK — Owner GOLD — Assessor LIVING DINING if r IL- NOOK 9 N e- J 2! 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