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6904 174TH ST SW.PDFiiiiiiiiiiii 1038 6904 174TH ST SW ADDRES - / 7//,;4 TAX ACCOUNT/PARCEL NUMBER: BUILDING PERMIT (NEW STRUCTURE): COVENANTS (RECORDED) FOR: CRITICAL AREAS:- o-o h6L] DETERMINATION: []Conditional Waiver Study Required E] Waiver DISCRETIONARY PERMIT #'S: DRAINAGE PLAN DATED: PARKING AGREEMENTS DATED: EASEMENT(S) RECORDED FOR: PERMITS ( PLANNING DATA CHECKLIST DATED: SCALED PLOT PLAN DATED: SEWER LID FEE LID #: SHORT PLAT FILE: LOT: BLOCK: SIDE SEWER AS BUILT DATED: SIDE SEWER PERMIT(S) #: GEOTECH REPORT DATED: STREET USE / ENCROACHMENT PERMIT #: FOR: WATER METER TAP CARD DATED: LATEMP\DST's\romis\Street File Checklist.doc Fla Critical Areas Checklist CA File No:. UA ZC01 6 Site hdormation (soils/topography/hydrology/vegetation) 1. Site Address/Location: (09 6 9 Mill -S+--5Vj V14116,Y)ds 2- property TAxAccount Number: - 00513) - 606—.( q�-> - 1 -7 3. Approxhnate Site Size (acres or 6quare feet)*- 4. Is this site currently developed? yes; Zno. PtATO 6P��(,�J If yes; how is site developed? 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: slopes present on site of more than 15% and less than 30% (a vertical rise of 10-feet over. a horizontal distance of 33 to 66-feet). Steep: grades of greater than 30% present on site (a vertical rise of 10-feet over a horizontal distance of less than 33-feet). Other (please describe): le56'S& e W/04 y� 'It 1A0-jWZ0Ce,-4 , /V/'// j 6. Site contains areas of year-round standing water. Approx. Dept�- 7 Site contains areas of seasonal standmg water: ;Approx Depth: What season(s) of the year? B. Site is in the floodway floodplain 0 of a water course. A-6 Al A16X-e- 9. Site contains a creek or an atea where water flows across the grounds surface? Flows are year-ratmd? Flows are seasonal? — QVhat time of year? 10. Site is primarily- forested meadow ;shrubs mixed urban landscaped Pawn, shrubs etc) <—� 11. Obvious wetland is preseftt on site: For City Staff Use Only 1. Plan Check Numbj if applicable? 2. Site is Zoned? I SCS mapped wil jpe(s)? bc,�t ( em cdlki 1/1 tT A (kruvood 2ra�6v 5-ald V /oqll eq S-t- 4. Critical Areas inventhry or C.A-'map indicat— rritical Area on site? 40"IfOlt CrO51-01 IVA �Cllc( Ao r4�\ S. Sibe within designated earth subsidence landslide hazard area? ITO DffERMINATION -STVPY REQUIRED Oct 29 07 11:08a Stacy Smith #j?2() (360) 691-4857 p.2 City of Edmon'ds Date /q 7 Z-00 -7 Devdopv=jt8erWoes]Dqp=tment My I�ecelpt #-. 7: PIwri6bgDivWw Critical Areas Filet. CEA_,U� -01" il!51 Phone; 425.771.0220 CrMcal Areas Chaddist Fee*- &.605.00 Q0 Fax 425.771.0221 Date Mailed to Appticant 77- �67 ne Critical. Areas Chocklist contained on d9s form is to be filled out by wW pmrson preparing a Developmertt Pam* AppliMfion. for the City of Eftonds prior to hWW sulmAtal of the application to the City. Mic purpose of Ihe ChedIdist is to enable City staff to determine Whether any potential Critical Areas are, or -iray be, present on the sul6ect InopcOy. The faformation needed to conpleft ffic Checklist should be easily available fim observations of the site a- dita available at City EW1 (Cddcal areas hwentorIM Maps, br soil surveys). A property, owner, or bob= aLdherized, rcpresentatiM mwt'fdl out (Im cbc*list� sip and daft it, and submit it to the Cdy. The Qbr wM ttview the c1mcklis4 make a precumory site viait and nuke a dctermhmfion of the mbseqawt steps necessaxy to complete a deMopmmt Pleam submit a vicinity nap, along with the skpazd copy of ibis ftm to amist City staff in findiag and locating The specific Inece of property descriiixd on dus Ibm In addifian, 6c applicant " include other perfinW information (e�g. situ p100; topography =qy, etc.) or studies m- conjunction With*3 cbeckfist to assistant staff in conVichng their prelimimy assessment of ft sit, -- The undersigned applicarrt, and his&cdbs heirs, and assigns, in owsideration an the proc essing of 1he, application agrF= to rekasr, inderanify, dcfmd and hold Ibe City of FAnmds barmless from aW end a damages;, including reasonable attomef s fees, arising from any acdon, or infiuctim based in whole or part upon Alm, tnideadin& ina� or hwomplex inforciatica furnished by the awlicant, Inwhedits agenu or co431cyces. a on, fion �*lf of tba owm as liskod below By3My4=h3Xe,ICerIifyIbaJt 111brxi! jywcwi& submiurd we tn= and coamt to ft bed of my knowlec* and tbat 11 ara bD Me MAI, Propefty 0imees AnthosizWon-' (0— By ny slgnau=6 I cartify flat I have authorized i&c abover Appfi=WAgent to apply for d ie mbjwt 11and we app&aticn, and grant my permission for ft pubho officials and ft staff of the City of Edmonds to entw die subject property for ft purposes of inspeefion . androstiAg dt=dant to ft avolicalion. __A�&GNATIMOFOWNRR)a�� PLEASE PRINT CLEARLY Owner/Applicant- �kppcftnt RepremWive: "e-, eo 'a/K.0L, 'Boqddh ZAACM tbn�ej U Rame, .,-j - _06(p 171141,54 _SVV (PL12�x 271LIt PqN? krE Stred Address Streei Address 6ixnbTAS q 902- �P It FaU W A- ot 17, 5Z city state zip city tate zip Telephone* Telephone: N96�2-29— Email address (option4 Email Address (optional): CITY OF EDMONDS CRITICAL AREAS RECONNAISSANCE REPORT Site Location: 6904 174 th Street SW Tax Acct. Number: 00513100014517 Determination: Study Required Determination #: CRA-2007-0154 Applicant: Stacy Smith Owner: Georgiana V. Gavrilovich CRITICAL AREAS RECONNAISSANCE REPORT: STUDY REQUIRED During review and inspection of the subject site, it was found that the site contains and/or is adjacent to critical areas, including Geologically Hazardous Areas, pursuant to Chapters 23.40 and 23.80 of the Edmonds Community Development Code (ECDC). There is a small area of the northwestern corner of the parcel which appears to have slopes in excess of 40%. The northeastern portion of the parcel has slopes in excess of 15%. There is also an approximately five-foot high rockery/retaining wall that nearly bisects the parcel running from the southwest to the northeast adjacent to an existing driveway. GENERAL CRITICAL AREAS REPORT REQUIREMENTS Critical Areas Reports identify, classify, and delineate any areas on or adjacent to the subject property that may qualify as critical areas. They also assess these areas and identify any potential impacts resulting from your specific development proposal. If a specific development proposal results in an alteration to a critical area, the critical areas report will also contain a mitigation plan. You have the option of completing the portion of the study that classifies and delineates the critical areas and waiting until you have a specific development proposal to complete the study. You may also choose to submit the entire study with your specific development application. Please review the minimum report requirements for all types of Critical Areas that are listed in ECDC 23.40.090.D. There are additional report requirements for different types of critical areas (see below). Note that it is important for the report to be prepared by a qualified professional as defined in the ordinance. There are options on how to complete a critical areas study, and there is an approved list of consultants that you may choose from. You may contact the Planning Division for more information. General Mitigation Requirements for all Critical Areas are discussed in ECDC 23.40.110 through 23.40.140. STUDY REQUIREMENT — EROSION HAZARD AREA It appears that this property contains or is adjacent to an Erosion Hazard Area. Erosion Hazard Areas include: 0 Those areas with Alderwood and Everett series soils on slopes of 15 percent or greater. Any area with slopes of 15 percent or greater and impermeable soils interbedded with granular soils and springs or ground water seepage. Areas with significant visible evidence of ground water seepage, and which also include existing landslide deposits regardless of slope. DEVELOPMENT PROPOSALS ASSOCIATED WITH EROSION HAZARD AREAS Development within an Erosion Hazard Area must meet additional criteria. • For erosion hazard areas with suitable slope stability, the only critical area study needed is an erosion and sediment control plan prepared in compliance with the requirements set forth in Chapter 18.30 ECDC as part of the construction documents. This option is at the director's discretion, per Edmonds Community Development Code section 20.80.050.G. • In areas where the slope stability is not suitable, projects within Erosion Hazard Areas will require a report by a licensed Geotechnical Engineer or other qualified professional. Note that it is important for the report to be prepared by a qualified professional as defined in the ordinance. • Report requirements are given in ECDC 23.80.050, and more generally in ECDC 23.40.090.D. 0 Development standards are given in ECDC 23.80.060 and 23.80.070 STUDY REQUIREMENT — LANDSLIDE HAZARD AREA It appears that this property contains or is adjacent to a Landslide Hazard Area. A Landslide Hazard Area is any area with a slope of forty percent .(40%) or steeper and with a vertical relief of ten (10) or more feet (except areas composed of consolidated bedrock). 0 Landslide Hazard Areas are further defined and illustrated in ECDC 23.80.020.B. In addition to the general requirements for Critical Areas reports referenced above, specific Critical Area report requirements for Landslide Hazard Areas are provided in ECDC 23.80.050, DEVELOPMENT PROPOSALS ASSOCIATED WITH LANDSLIDE HAZARD AREAS Development is restricted within a Landslide Hazard Area and its buffer. • Projects that will intrude into these areas will require a report by a licensed Geotechnical Engineer. • The criteria that are applied depend on the amount that the buffer is reduced. • The buffer can be reduced to a minimum of ten (10) feet (with an additional 15' building setback per ECDC 23.40.280) if a report is prepared that meets the standards listed in ECDC 23.80.050. The alteration must also meet the requirements listed in ECDC 23.80.060. In addition, proposals to reduce the buffer to less than ten (10) feet must comply with the design standards listed in ECDC 23.80.070.A.3. ALLOWED ACTIVITIES Certain activities are allowed in or near critical area buffers as specified in ECDC 23.40.20. If you have any questions about whether your proposed development qualifies as an allowed activity, please contact a Planner for more information. 2 EXEMPT DEVELOPMENT PROPOSALS Certain development proposals may be exempt from Critical Areas Requirements (ECDC 23.40.230). If you think that a specific development proposal may be exempt, contact a Planner for more information. Michael Cluaston. Planner 4w. Name Signature Date NOTE: Cited sections of the Edmonds Community Development Code (ECDC) can be found on the City of Edmonds website at www.ci.edmonds.wa.us. 6904 174th Street SW All T x, _0 7. rip Jt U r, OR ::�q �A IJ- "This map displays LIDAR data at approximate 2-foot contour intervals This map is for information purposes only and should not be relied upon for any action. Actual topography should be verified in the field by survey for accuracy. This map is provided with all faults on an "as is" and "as available" basis. No warranty is any kind is given. Users of this map agree to indemnify and save harmless the City of Edmonds, its officials, officers, employees and/or agents from and against any claim, demand or a tion, irrespective of the nature of the cause of the claim, dem d or action, arising out of any use or possession of this m K-11', M�z Mf IC I inch ecivals 40 fi V4 W n r: TERRA ASSOCIATES, Inc. Consultants in Geotechhical Engineering,'Geology RESUB and Environmental Earth Sciences MAR 2 4 2008 EU ON Oft wft�h FILE kP1 Ms. Melissa Gaillard Alexander Reed Construction P.O. Box.1465 Marysville, Washington 98270 Subject: Plan Review Gavrilovich Residence 6904 —dtV eet SW Edmon s, ashington Reference: Geotechnical. Report., Gavrilovich Residence, Project No. T-6178, prepared by Terra Associates, Inc., dated January 25, 2008, Revised February 1, 2008. Dear Ms. Gaillard: March 24, 2008 Project No. T-6178 As requested, we reviewed building plans prepared for the subject project. The purpose of our review. was to verify that geotechnical engineering recommendations outlined in the referenced report were incorporated in the provided plans. This letter also provides seisrfflic design parameters per 2006 International Building Code (IBC) seisn-ft requirements. We were provided the following building plans for our.review: Sheets I through 4'of 4, prepared by Design- Consultants, dated September 25, 2007 0 Sheet 4A of 4, prepared by Design Consultants, Stamp dated October 17, 2007 Sheet S I of 1, prepared by JRR Engineering, Inc., dated October 17, 2007 The plans indicate the single -story structure will have its main floor framed over a crawl space, with the attached garage floor constructed with a slab -on -grade floor. Geotechnical design parameters outlined in the foundation notes on Sheet 2 of 4 and the general notes on Sheet 3 o f 4 indicate foundations were dimensioned for an allowable bearing capacity of 2,000 pounds per square foot (psf). For determination of seismic forces, per the 2006 International Building Code (IBC), site class "D" was used in building design. 12525 Willows Road, Suite 101, Kirkland, Washington 98034 Phone (425) 821-7777 * Fax (425) 821-4334 i Ms. Melissa Gaillard March 24, 2008 Conclusions Based on -our review of the plans, geotechnical parameters used in design of the building 'foundations, and subsurface building drainage details are consistent with those presented in the referenced Geotechnical Report. Undisturbed surfaces of the -site's native soils, or properly compacted structural fill will provide adequate support of footings designed for the 2,000 psf bearing capacity value shown on the plans. The referenced Geotechnical Report provided a seismic soil site class value relative to the 2003 International. Building Code (lBC). Currently, state and localbuilding officials have adopted the 2066 International Building Code (IBC). Based on soil conditions we observed at our site explorations completed for preparati on of the referenced Geotechnical Report, and our knowledge of the area geology, per Chapter 16 of the 2006 IBC, Site Class "C" can be used in determining seismic forces for structural design. We trust the Information presented is sufficient for your, current needs. Ifyou have any questions or require additional information, please call. Sincerely yours, TERRA ASSOCIATES, INC. Carolyn chepp�r, E.I.T. Staff Engineer Kevin P. Roberts, P.E. Senior Engineer r. kqv 3-Z,1f-0'? F ',"RES Project No. T-6178 . Page No. ii TERRA,ASSOCIATES,, Inc. 4 A ..,,Consultant's in Geotechnical E�gineering, deology RECEIVED and Environmental Earth Sciences FEB 2 1 .2008 BUILDING DE,VARIMENT* CITY OF EDMONDS �MIEET FILE January 25, 2008 Revised February 1, 2008 Pro ect No. T-6178 Ms. Melissa Gaillard Alexander Reed Construction 'P.O. Box 1465. Marysville, Washington. 98270 Subject: deotechhical Engineering Study Gavrilovich Regidence 6904 — 174th Street SW' Edmonds, Washington Dear Ms. Gaillard: As requested, we have conducted, a geotechnical enginee ring study -for the subject project. The attached report presents our findings and recommendations for the geotechnical.aspects� of project design and construction. In our opinion, the soil and groundwater conditions are suitable for the planned' residential construction. Undisturbed. native soil subgrades or compacted structural fill placed above these native soils will provide - suitable bearin for standard spread footing foundations.'. g We appreciate the opportunity to be of service to you during the design phase of this project, and look forward to working with you'during'the final design And construction phases. We trust the information presented in this report is sufficient for your current needs. If You have any questions or- required. additional. information, please call. Sincerely yours, TERRA ASSOCIATES, INC. Kevin P. Roberts, P.E. ?—Coe, Senior Engineer ST AL cc: .,Ms. Stacy Smith, Smith Land Development Services ==won 12525 Willows -Road,'Suite. 101 Kirkland, Washington 98034 Phone (425) 821-77.77 Fax.(425) 82.1-4334 TABLE OF CONTENTS Page No. 1.0 Project Description ........................... .............................. ............... ......................................... I ......... 1 2.0 Scope of Work .............................. .................................................................................................... 1 3.0 Site Conditions ...................................... ................................................................................. * ............... 2 3.1. Surface ..... . ........................................................................................................................ 2 3.2 Soils ....................................................... ................. ....... .............. ........ ............................ 2 3.3- Groundwater ........................................................................ ........... 3 4-0. Geologic Hazards, .................... : ..................... ; ........................................................ ........ ............... 4.1 Erosion ....................................................... ......................................................... .............. �. 3 4.2 Seismic Considerations ........................... ......................... : ............................................... 4 4.3 Landslide ................. .......................................................................................................... � 5 5.0.- Discussion and Recommendations ........................................ I ...... ..................................................... 6� 5.1 General ....... ................................................. : ......... I ............................................................ 6- 5.2 Subgrade Preparation and Structural Fill ....... ................................................................ 6 5.3 Foundations ...................................................................................................................... 8 5.4 Slab-on-,Qrade Floors'. ......................................................... ! ................. ................... 8 5.5 Rockeries ................................ :.: .............................. ........................................................... 9 5.6 Drainage .............................................................................................................................. 9 5.7 Driveway Pavement ........................................................................................................... 10 Additional Services ..................................................... .................................................................... 10 6.0 7.0 Limitations ................. .......... ........................................................................... .............................. �.. 10 Figures Vicinity Map .......... ........ ..... ................ .. Figure I ............................................................................. ............... ........ Figure 2 Exploration Location Plan .................. ; ........... I ................ I ........................................................... Generalized Geologic Section ................................. Figure 3 ......................... ......................................... ; ......... Reinforced Fill/Rockery Detail ............... .......... ...................................................... ......................... ... Figure 4 Appendix. Field Expl6 ration and Laboratory Testing ..... ..................................................................................... Appendix A Slope Stability Analysis�Qdtpu� ..................................... .................................................................... Appendix B Reinforced Fill Rockery Design'Calculations.. ......................................................................... .. Appendix. C - Gdotechnical Report Q§vrilovich Residence 6904 " 174th Street SW, Edmorift, YVas,h1ingtoin, PROJECT DESCRIPTION The project- consists of dev'eloping'ap approximately 1/4-acre lot- for single-family residence construction. The provided schematic site plan shows that the residence will occupy the centrAland southeastern portions of the lot. The site's existing rockpry and driveway will be re -located northward along,the crest of the northwestern slope to accommodate construction of the new residence. Plans indicating proposed building, -diivewa y, and rocker'y elevations are unavailable'for our, review. Based on e observations of the existing topography, we anticipate that the proposed driveway rocke ' will be' six- to eight ry feet (maximum) in height, and will be constructed primarily against fill soils placed to raise building pad grades. Sit We understand that driveway grades will likely approximately -match current elevations north'and adjacent to,the existing driveway. We anticipate the residence- will be constructed with spread footing foundations and a slab -on -grade floor for the garage. We expect'structural. loads will be ap roximately tw6 to'three kips per lineal- foot for. continuous bearing p walls. The recommendations contained in the following report are� based on our understanding of these design features. If actual features var"y or'changes -are made, we should. re . view them in order tom6dify our r6commendationsi. as requited.. We should review final design drawings and specifications to verify that our recommendations have . been properly interpreted and, incorporated into project design. 2.0 SCOPE OF WORK Our work was completed in accordance with our authorized proposal dated December 14, 2007. Accordingly,, on January 11, 2008, we advanced 2 test borings to depths of 5'5 feet and 11 feet below, existing surface grades. A hand test pit was also excavated to a depth of, two feet at the toe of the, northern slope in order to correlate -geology with the upper test boring. Vsing �the information obtained from, the subsurface exploration, we performed analyses I to -develop I geotechiiicalrecommendations -for proj ect de'si gn and construction. Specifically, this report addresses the following: Out- slope observations, and soil and �roundwater conditions Geologic hazards Slope stability analysis Foundations January 25, 2008 Revised February 1, 2008 Project No. T-6178 Slab -on -grade floors Structural fill Reinforced fill/rockery design Subsurface drainage Driveway pavements The City of Edmonds Critical Areas Reconnaissance Report indicates the site contains both Landslide and Erosion Hazard Areas. It -should be noted that the recommendations outlined in this report regarding drainage are associated with soil - strength, design earth pressures, erosion, and stability: Design and performance -issues with respect-to'moisture as it relates to the structure environment (i.e., humidity, mildew, mold) are beyond Terra Associates' purview. A building envelope specialist or contractor should be consulted to address'thes'e issues, as needed. 3.0 SITE CONDITIONS 3.1 Surface The site is an approximately 1/4.-acre lot located at 6904 — 174th Street SW in Edmonds, Washington. The approximate location of the site. is shown on Figure 1. The site is bordered on the east, south, and west by sin gle- family residences. The site is bounded on the north by 174th Street SW. An asphalt driveway extends diagonally ftom the, northeastern comer of the site to the single-family residence south and adjacent to the site. A five- to Six7f0ot high (maximum). cut rockery extend§ along the southern edge of the driveway. The southern half of the site is relatively flat, with slope gradients increasing toward the driveway entrance. An approximately 12-foot high slope leads down'to 174th Street SW at the slope's northwestern comer. The slope"s overall inclination is approximately 1.7:1 (Horizontal:Vertical).,, We observed two small rockeries accommodating vertical grade breaks across mid -slope, and a short rockery along- the slope's toe. No indications of past or current soil movements, zones of emergent groundwater, or erosion were observed on the slope. Vegetation on the slope primarily consists of berry brambles. 3.2 Soils Boring�13-1 showed eight inches of topsoil overlying weathered till comprised of medium dense silty sand.with gravel to a depth of approximately two 'feet. The weathered till horizon was in turn found underlain 'by' unweatheredtill consisting of very dense silty sand with gravel to the total depth of the boring. Page No. 2 January 25, 2008 Revised February 1, 2008 Pro ect No. T-6178 We observed undocumented fill ditectly'bene'ath ten.inches of topsoil. in Boring -B72 to a depth of approximately. sevenfeet. The fill consists' of loose -becoming medium dense: silty sand with variable gravel content.. *Weathered and unweathered. horizons of very dense till soils consisting of silty gravelly sand grading with depth to silt with sand were encountered be neatli the -fill to, th e total depth of the test boring. shallow hand test pit, TH-3 excavated to. a d.epth pf two feet. at -the toe, of the slope found undocumented fill to. 'a depth of 1.5 feet. Weathered till,cohsisting of silty fine sand with few gravels was, observed beneath the fill soils. The Preliminary , Surficial. G'eologic Map of the Edmonds East and Edmonds West Quadrangles, Snohomish and King Counties, Washington, (Mkkey Smith, - 1975) shows soils at the site mapped as''Yashon- Till (Qvt). The very dense silty sand and sil I t with sand found.in our test borin& is consistent with the published -description of 9 this soil unit. 3.3 Grotindwater No groundwater'was observed during, advancement of the test borings at the site. In addition, no indications, of emergent groundwater on the slope face -were observed at the time of otir,visit. .4.0 GEOLOGIC HAZARDS' 4.1 Erosion City of Edmonds Municipal Code, Chapter 23.80..020 defines.'Efosiqn, Hazard Areas", in part as: 1. Those areas of the City,of Edmonds containing soils that may experience severe to very severe erosion hazard. This group'of soils includes, but is not limited to, the following when they occur on slopes of-.1 5 percent or greater: a. Alderwood soils (15 to 25 percent slopes) The USDA Soil Conservation Service "Soil Survey of Snohomish County Area Washington" shows the soils at'. the site m'apped'as Alderwood gravelly sandy loam, 15 to 25, percent slopes. The till -soils observed in.the test c 'loping areas meet the City of Edmonds bonings are consistent with this classification. A cordingly, the northern s criteria for classification as erosion hazard areas. Erosion protection measures required,by City of Edmonds, and as indicated on the final plans will need to be in place prior to and during grading-aciivity on the site. As a . mimmum, we recommend implementing the following erosion and sediment control.Best Management Practices (BMPs) prior to, during,- and immediately following clearing and gradin C e g a tiviti6s at th site. Page No. 3. e. Limit disturbance to areas where construction is imminent. Determine staging areas for temporary stockpiles of soils removed from the slope. Provide t6inpo'rary'cover'for exposed soils and soil stockpiles during periods of inactivity. Temporary. cover may consist of.durable plastic. sheeting that is gecurely, anchored to the ground surface or straw mulch. Containment Install 'a silt fence along the site margins and do�vnslope of the disturbed areas. 'The silt fence should be in place before work on the slope is initiated. • 'Construct shallow drainage swales at, the top of the slope"to intercept surface water flow, and route the flow away from the construction area to a stabilized discharge point. Surface water must not discharge at the top or onto the face of the steep slope. • Provide on -site sediment retention for collected r.unoff. Terra Associates, Inc.' should observe the installation of all -erosion and sedimentation measures at the site and make periodic, visits to observe site conditions to verify the performance of the measures. The contractor. should perform daily review and maintenance of all erosion and sedimentation control measures at the site. 4.2 Seisxrdc Cohsiderations City of.Edmonds Municipal Code,Chapter 23'.80.020 defines "Seismic Hazard'AreAs" as areas subject to severe risk of damage as a result of. earthquake -induced ground shaking, sl6pe'failure, settlement, soil' liquefaction, lateral spreading, or surface faulting. We evaluated the potential of.ground rupture at the site resulting from a severe seismic event. Review of the Quaternary fault and Fold Database of the United States (USGS Earthquake Hazards Program) has identified the presence of a southeast -northwest trending Quaternary fau I It located approximately five rililesnorth of the project site. Due to the absence.of surficial indications of rupture in the vicinity of the'site, and the distance from the, site of the nearest mapped fault, it is our opinion'that the potential of surface. faulting. at the site resulting from a severe seisnuc event is low. Liquefaction is a phenomenon where there is a reduction or complete loss of soil strength due to an increase -in water pressure induced by vibrations.- Liqudfactiow mainly affects geologically -recent deposits'of loose, fine-. grained sands that are below the groundwater table.. Basedon the medium dense to very dense nature of the. site's soils; and the absence of groundwater, it is our opinion that the risk for liquefaction to occur. at this site du'riing an. earthquake is negligible., January 25, 2008 kevis,ed Februariy-1, 2008 Pro ect No. T-6178 MC Soil Site Class Based on the soil conditions encountered. and'. the. local geology, per. Chapter 16 of the 2003 International Building Code (MC),' site class "C'!'Should be used in structural design. 4.3 Landslide City of Edmonds Municipal.Code, Chapter 23.80.020 defines "Landslide'Hazard Areas"in part as*. - Any area with slo,oe-of 40 percenf'or'steepe'r and with a vertical relief of. 10 or more feet,except areas .composed of consolidated rock. Due to its height and inclination, the 'northwestern slope meets the above City of Edmonds criteria fbr classification as 'a. landslide hazard area. Slope Stability Analysis Slope stability analyses were completed in order to assess- relative slope. stability.of the northern slope for the before and after construction cases. The post -construction analysis 'included traffic surcharge loads from the n' 6osen as Cross -Section A -A' using.the adjacent driveway. Theanalyses were performed at the critical locatio computer program WINSTABL. The cr6gs-sect.ion location is shown on Figure 2.. Our analysis considered both static and the pseudogtatic (seismic) conditions. A horizontal acceleration value. of 0. l6g was used in the pseu'd6static analysis to'simulate slope performance under earthquake loading, This ground acceleratio* n value is one-half the peak ground acceleration (PGA),value of 0.31 representing the PGA for a 1Q percent exceede'nce/50-ye4r event in Edmonds, Washington.. Section 5.10.3.1 of'the Federal. Highway, Administration (FHWA) Geotechfiical Engineering Circular No. 4 and AASHTO. (1996) recommend using one- half of the PGA value in pse-ud.ostatic, global stability andlyses The results of our, slope stability analysis,'as -shown by the- lowest safety factors, are presented inthe following table. Graphical and tabulated output from the stability analysis results are presented in Appendix-B. Table. 1 — Slope Stability Analysis Results Condition Analyzed Minimum e Factors Static (A-A'Sec n �tio Seismic* -(A-A'Section) -Existing slop� 1.61 1.18 Post'Construction January 25,.2008 0 Revised February 1, 20 8 Piro 6 ject No. T' 178_ 5.0 DISCUSSION AND RECOMMENDATIONS 5.1. Ge'neral Based 'on our study, it Js our opinion that the site is �suitable for, the ..proposed constiuction from'a geotechnical standpoint. The proposed residence can'be -supported on conventional spread,footing foundations bearing on the competent native soils, or on,conipacted* structural fill placed -above these native soils. We aritipipatethe on -site Silty. sand soils -will be.suitable for use as structural fill -in'the,,buil.ding,iirea'. However, these -soils are''w"etafid,contain a significant arn6un I f offm6s.' Accordingly, unless these soils I are driedthrough aeration, or. are . treated. with soil Amendments, they, will be difficult to compact as. structural fill. The owner should be, prepared to. import fide-drafning granular material. for use'a:s structural, fill and backfill for reinforced earth rockery construction,- and wher& moisture conditions prevent. the use, of, on -site materials in'building'areas. The stability analysis. results, Yielded - minimum, safety, factors' that, are considered by local geotechnical engineering. practice as, -acceptable for'both the.'static' and seismic (pseudostatic) loading cases. Based on th6 analysis results', and due tothe competent nature of the till. soils,'the stability analyses indicate the slope is stable with fespect to deep-seated failure; and is expected to remain stable, for the post -construction case under,both static and modeled seismic loading'conditions. A minimum ten -foot wide driveway setback'should be established from,the top edge of'the- "landslide- hazar& �r6a" slopes at,the *site. If desired; driveway construction closer to these- slopes. is possible with retaining. wall C 'on. c�ase, the setback distance may be determined by maintaming,a minimum I c6nstru, ti In that, late.ra - separation distance often feet between the lower.,outer edge of, a driveway retaining wall footing and the face,of the slope. The'followin aiding these-issues-and'other geotechnical design g sections ptov'ide, detailed recommendation's reg considerations. These recommendations -should b , e incorporated int othe fin�al design drawings 'and construction specifications. 5.2 'Subgrade Preparation and Structural Fill,' To prepare, the site, for -construction,. all,veg6tati'on, organic surface.soils, and other deleterious. materials should', 'be -.stripped, And iemove'd, from the areas* under construction. -Organic topsoil., wilt not be suitable for use as structural fill, but may be used for limited depths in nbnstructufal are as. Once cleart'n4andstfipping operations are complete, buildin� cuts, driveway grading, and reinforced fill/rockery iti d the site.' Prior to, placing fill, all exposed surfaces of the loose, upper soils should - construction can be in ate. at becompacted. In 'addition, "probing should be done by Terra Associates personnel to determine it, any isolated soft and yielding -areas ii re'pTesdnt. jf excessively yielding ar eas are bb -served' and cannot- be* stabilized'in, place by compaction', the affected soils should be excavated and. remoyed� to hrin'bearing and restored.to grade with - new, structural fill. If the depth of excavation to remove' unstable soils is. excessive, use of a*. geoiextile sMirafi500Xoreq'uivalent'can�be,co'nsideredin o unction with structural reinforcing/separation fabtic,,such a C, nj fill. Our -experience has- shown that, in general, a minimum . of 18 inches of a clean, granular, structural fill over the geotextile fal5ric.should establish a stable bearing surface.. Page No. 6 I I I L January 25, 2008 Revised February 1, 2008 Project No. T-.6178 Our study indicates that the native soils contain -a sufficient amount of fine.s (silt and clay size particles) that will make them difficult to compact a's structural fill when too wet o*r too dry. Accordingly, the ability to use the soils from site excavations as structural fill will depend on their moisture content and the prevailing weather conditions when site grading activities take place. Soils that are too wet to properly compact can be dried by aeration during dry weather conditions. If grading activities ate planned during the wet winter months, or,if they are initiated during the summer and extend into fall and winter, the owner should be prepared I to.import wet Weather structural fill. For this purpose, we recommend importing a granular soil thaf meets the following grading requirements- U.S. Sieve Size Percent Passing 3 inches 100 No. 4 75 maximum No. 200 5 maximum* *Based on the 3/4-inch fraction. Prior to use, Terra Associates, Inc. should examine and test all materials imported to the site for use as structural fill. Structural fill should be placed in uniform loose layers not exceeding 12 inches and compacted to a minimum of. 95 percent of the soil's maximuin. dry density, as determined by American Society for Testing'and Materials (ASTM) Test Designation D-698 (Standard Proctor). The moisture content of the soil at the time of compaction should be within two percent of its optimum, as determined by this ASTM'standard; In nonstriictural areas, the degree of compaction can be reduced to 90 percent. We recommend grading permanent fill slopes to an inclination of 2:1 or flatter. All pemarient slopes graded at the site must be protected from erosion by planting with erosion-resisiant vegetation. All excavations at the site associated with- confined spaces, such as lower building level -retaining walls, must be completed in accordance with local,, state, or federal- requirements. Based on the Washington State Department of Labor and Industries current occupational safety and health regulations, the loose to medium dense soils would be classified as Type C soils, and the underlying very dense till soils would be classified as Type A soils. Accordingly, for temporary excavations of less than 20 feet in depth, the side slopes in Type C soils should be laid back from the toe to the crest of the slope at an inclination of 1.5:1 (Horizontal: Vertical) or flatter. The side slopes in Type A soils should be laid back at a slope inclination of 0.75:1 or flatter. All exposed slope.faces should be covered with a durable reinforced plastic membrane during construction to prevent slope*raVeling and rutting during periods -of precipitation. This information is provided solelyfor. the benefit of the owner and other design consultants, and should not be construed to imply:that Terra Associates, Inc. assumes. responsibility for job site safety., It is understood thatjob site safety is the sole responsibility of the project contractor. Page No. 7 January 25, 2008, Revised February 1, 2008 Project No. T-6178. 5.3 Foundadons The residence can be supported on conventional spread footing foundations bearing on competent native soils or on st�u&uxal fills placed abovethesp native soils. Perimeter foundations'e'xposed to the.weather should be.at a minimum depth' of 18 inches- below final,exterior grades. 'Interior foundations can be'.'c,onstructed at -any donvenient depth below -the- floor slab." We recommend designing foundations for a net allowablebearing capacity of 2,500 pounds per square foot (psf). Foi short-term loads, such as wind'and seisimic, a one-third increase in this allowable capacity can'be used in design. For these loads, building settlements should 'be less than one-half inch total- and one4bin-th. inch differential. For designing foundations -to'resist I a*teral loads, a base friction coefficient of 0.30 can be med.in design. Passive earth.pressures acting on the sides of the footings and buried'portions of the foundation stem walls can also be ;dered. We recommend calculating this lateral resi stance using an equivalent fluid weight of 300 pounds per consl cubic foot (pcf).,.We recommend not including the upper 12 inches of soil in this computation because'it'can be affected by weather, . or disturbed by future grading activity'- - This value assumes the foundation' will. be constructed neat against competent native soil or backfilled with� structural. fill, as in Section. 5.2 of this repori. -The recommen . ded..values include a safety'factor of 1.5. 5.4 Slab-on-Giade Floors Slab -on -grade floors'may be supported on subgrades,prepared as re�ommenddd,in S6ctibn 5.2 of this report. Inunedia'te'ly below,the floor slabs, we recommend placing A four -inch thick capillary break layer. of clean, free- -than three percent b w i ht of material passing the No. 200 draining, coarse sand or fine gravel that has les�s y P9 sieve. This material will feduce the. potential for upward capillary movement of Water through the underlying soil and subsequent wetting of the floor slabs. The capillary 'break layer,' will not prevent moisture intrusion through the slab caused, by water vapoT. transmission: Where moisture by -.vapor transmission is undesirable, such as covered floor areas, 'a common practice is to� place a durable, plastic membrane on the capillary break layer and then liover.the membrane with a layer of clean sand or fine grave I to protect it from damage during consiruction,,and aid in un iform curing of the conciete slab. 'It should, be Pot . ed that if the sand or gravel layer overlying the membrane is saturated.prior to b pouring the sla it will be ineffective in assisting in uniform curing of the slab, and can actually serve as a water supply for moisture transmission through the slab'affecting floor �overin gs. Therefore, in. our opinion, covering themembrane I with a laypr,of sand or'. gravel should be avoided if flo I or slab constru 'ti6n occurs d I uring. the wet C winter months and the layer cannot be effectively drained. y , Other methods are available for preventing or reducing water vapor transmission through the slab. We recomme . nd consulting v�ith a building envelope specialist or contractor for additional assistance regarding this. issue. Page No. 8 January 25, 2008 Revised February 1, 2008 Project.No. T-6178 5.5 Rockeries It should be noted, that rockeries are' not engineered structures that, are designed to retain earth. in a manner.similar to a cast -in -place concrete or gravity block wall systems. 'Rocks used to construct the wall will by virtue of their mass enhance'sta . bility; however,the soil, against I which the rock ery is I constructed must b I e inhe . rently stable and able to stand unsupported in a near -vertical condition. For the case.of rockeries that are four feet and higher that face structural fill, . the geotextile reinforcement layers provide the necessary stability to'. the soils'behind the rockery. We recommend' constructing r6ckeries that,are four feet and greater in height -against fill. reinforced 'with geotextile. A design detail for reinforced'earth rockery construction is shown as Figure 4. Rockery construction should conform to the Associated Rockery Contractors (ARC) Standard Rock Wall Construction Guidelines. Our design for 'reinforced fill/rockery retaining walls addresses internal, external, ind global wall stability considerations. The reinforced fill rockery retaining Wall design was completed using the computer program MSEW v.'2.0 published by ADAMA Engineering, Inc. The analyses incorporated'seismic horizontal earth pressures calculated based on procedures outlihedin.Lateral Stressej�in the Ground and Design of Earth fletaining Structures, published by ASCE (1972) using a ground acceletation,value' 'selected as described in Section 4.3 of this -report. All analyses yielded acceptable factors of safety for both static and seismic cases. ry -off Reinforced fill/rocke wall,design calculations are attached in Appendix,C for building icial review. All subgrade preparation'activities'associated, with construction of the walls must be completed in accordance with recommendations as outlined in Section 5.2 of this report. Where. rockeries less than four feet in height will be constructed against structural fill, the'structural fift should be overbuilt and then cutback prior, to constructing the rockery. This will provide a more competent. and, stable soil face behind the rockery., 5.6 Drainage Surf"e Final exterior grades should promote free'and positive drainage away from the residence at all times. Water must not be allowed to pond or,collect adjacent to foundations oi within the immediate building area. We recommend providing a gradient -of at least three p ercentfor a minimurn distance of ten, feet from the building perimeter, except in paved locations. In paved locations, a minimum gradient of bne percent should be provided, unless provisions are included for collection and disposal of surface wateradjacent to the structure. Surface water must not be . allowed to flow uncontrolled. over the crests of the site slopes and embankments. Surface water should be directed away from the slope crests, to a point of collectionand controlled �discharge. If site.grades do not allow for directing surface. water'away from the slopes, water- should be collected and tightlined down the slope face.in a controlled. manner. Page No. 9 January 25, 2008 Revised February 1, 2008 Project No. T-6178 Subsurface We recommend installing a continuous drain along th6 outside lower edge of the perimeter building foundations. The foundation drains should be tightli.ned to an approved point of contr olled discharge independent of the roof. drain system. Subsurface drains must be laid with, a gradient sufficient to promote� positive flow to the point of discharge. All- drains.should be provided with cleanouts at, easily accessible locations. These cleanouts should be. serviced at least once every year*: 5.7 Driveway Pavement Priveway pavem . ent should be constructed on subgrades, as described in Section 5.2 of this report.. Regardless of therelative compaction achieved, the subgrade must be. firm and unyielding before paving. Proofrolling the subgrade with heavy construction equipment should be completed to verify this condition. We recommend. using the. following pavement design section -for driveway construction at the site: Two. inches asphalt concrete (AC) over four inches crushed surfacing base course (CSB,C). Asphalt concrete and,crushed rock'base should.meet the, requirements for V24nch !RdA, as outlined in Washington State Department of Transportdti6n's,(WSDOT) standard specifications. Long-term- pavement performance 'Will. depend on, surface.drainage. A poorly -drained pavement.section will *be subject to premature failure as a result 'of surface water infiltrating into 'the subVad.e soils. andr6duding their supporting capability. For optimum pavement performance, *we recommend surface drainage gradientsof at. least two percent. Some degree of longitudinal and transverse cracking of the -pavement surface should be expected over- time. Regular maintenance should be planned to, seal cracks when they occur., 6.0 ADDITIONAL SERVICES' Terra Associates, Inc. should -review,'the final project desigii�.and specifications in order to verify that earthwork and foundation recommendations have been properly interpreted and. incorporated, into project design. -We recommend that we provide geotechnical services during construction to observe compliance. with our design oncepts, specifications, and re ommendations. This will -'allow for expedient -design changes if, subsurface c c conditions differ from those anticipated prior to the start of construction.. 7.0 LIMITATIONS We prepared this report in accordance with g e�'neirally accepted geotechnical engineering practices. No other warranty, ekpressed'or implied, is made. this report is the copyrighted property of Terra Associates, Inc. and is intended for'specific application, to the,Gavril6vich Residence project in,Edmonds, � Washington. 'This report is for the exclusive use of Alexander Reed Construction and its authorized representatives. Page No. 10 January 25; 2008 Revised February-1, 2008 Project No. T-6178 The analyses and rec*o'mme I ndations presented in this report are based on data obtained from the on-site'te9t pits.. Variations in soil conditions. can occur, the nature, and extent of which may not become evident, 'until construction; If variations appear evident, Terra Associates,:. Inc. -should be requested to reevaluate the recommendations,i*n this -report prior to proceeding with construction. Page NoA 1 K�"4LE — � - . - �. 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I - Ix ST. �sw VA:9 IL �g , - _-x . 20ST11 PL ;KJ._2pZ7H PL Sw ir- �E __208TH PL W 2 f 206TH ,L" TH 31; STI 001 0 -ST I NOW zos St"117H ST SW LL si- I r4TH ST 2 'V� KE 213TH I :� 211TH ST I ST_'1 Sw-' T I D PARK 7121H Sw 2 2T_ 2.13TH PL cl S c RIDE 4A w 3 1 PL Sw ?151H ST SW si 210, _S! 2! Ic sw 21 D1 214 T m 21 '1 ST Sw ui 2A M STEVENS 6600 T 7-1- Sw & Z17Ttf ST p M)SP FL., Z 6JB Lj i 29 MOUNTLAKE 1 V 2141H "I TNC_�_ TER CE -si Zi ST TIL Sw 21 ItL GHT HS L19 I "� [ - L 219TH 4" ; 1 -�w ST 220TH I H - C., lit iK-, REFERENCE: THOMAS GUIDE CD-ROM, KING/PIERCE/SNOHOMISH COUNTIES, 200, 1T TO SCALE Terra VICINITY MAP GAVRILOVICH RESIDENCE Associates, Inc. EDMONDS, WASHINGTON Consultants in Geotechnical Engineering Geology and Environmental Earth Sciences Proj. No.T-6178 1 Date FEB 2008T Figure 1 4 -1A th qf Sw zv_ 14U NOTE: THIS SIT E PLAWIS SCHEMATIC. ALL LOCATIONS AND APPROXIMATE SCALE IN FEET DIMENSIONS ARE APPROXIMATE. IT IS INTENDED FOR. REFERENCE ONLY AND SHOULD NOT BE USED FOR LEGEND - DESIGN OR CONSTRUCTION PURPOSES; APPROXIMATE BORING LOCATION REFERENCE: SITE PLAN PROVIDED BY CLIENT APPROXIMATE HAND TEST PIT LOCATION Terra EXPLORATION LOCATION PLAN GAVRILOVICH RESIDENCE Associates, Inc. EDMONDS, WASHINGTON 'Consultants in Geotechnical Engineering Geology and Environmental Earth Sciences P�pj. �o:T-6178 Date FEB 2008' Figure 2 F