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15515 75TH PL W.PDF1111111111116033 15515 75TH PL W ADDRESS: %5 TAX ACCOUNT/PARCEL #: �' Q BUILDING PERMIT (NEW STRUCTURE) #: COVENANTS (RECORDED) FOR: CRITICAL AREAS #: e - DETERMINATION: ❑ Conditional Waiver Study Required ❑ Waiver CRITICAL AREAS #: DETERMINATION: ❑ Conditional Waiver ❑ Study Required ❑ Waiver DISCRETIONARY PERMIT #'S: ,—® DRAINAGE PLAN DATED: `7 PARKING AGREEMENTS DAT D: EASEMENT(S) RECORD FOR: PERMITS (OTHER — list permit #'s): PLANNING DATA CHECKLIST DATED: �' X 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/ENCROACHMEN PERMIT #: FOR: WATER METER TAP CARD DATED: OTHER: LATEMP\DST's\Forms\Jana's Street File Checklist 5-14-08.doc 1� .L"A-w e. �,.t-. 4q,VD-o bCA :' 445', W lob f�e� �I � l awn �• � 9 v� s Qe ct�� PLANNING DATA STREET FILE SINGLE FAMILY RESIDENTIAL FA Name: jz0V% & Gjtohav1 Otrd Date: 03• Z•L• • ?2oOg Site Address: 1 15 1 j � 5 �-t7 TH p� QGe, Wit, 2t Plan Check #: BLD - 2008 . D 11 �- Project Description: NeW CJ r- R- 6n i-h,e e S L RA , liee ecd c. 0.10) Reduced Site Plan Provided: (YES / NO) Zoning: jZ-5 — yo Map Page: 50-+ Corner Lot: YES NO) +5T'4 Flag Lot: (YES / NO Critical Areas Determination #: G F-A • I- D O U • 005 S Study Required ❑ Waiver SEPA Determination: ❑ Exempt D G �`p��r�� 7 per' Needed Required Setbacks Street: ' 0 Sid �jSIIO i �3s/10 2cks Rear- W 101 Actual Se Street: '3• ,1 a Side: Side: (0(0 Rear: ' 0 1 .-Detached-Structures • Rockeries •Retaining Walls •Fences *Trellises *Arbors Bay Windows • Projecting Modulation • Stairs •Covered Deck •Covered Porch •Eaves Chimney • Elevator -Penthouse • Uncovered Unenclosed <30" Deck • Porch • Patio Parking Required: Parking Provided: 2 Lot Area: 0 •3 9 0. Lc5 l U C5,51- Lot Coverage: Lot Coverage Calculations: 72 V5 C� I V"lM Building He/ ht Datum Point: 57fj LJL/ Datum Elevation: 2 (b • Maximum Height: 2ej 1 Z y t �-v Actual Height: '!i5 . tF C 1 ADU Created: (YES / fJ0 Subdivision: LLA• y00-•• (09 O arpyoved' /recorded"Os oto O(a Sa0 Legal Nonconforming Land Use Determination Issued: (YES / O Other .* I andoc-a fe, ?LaAn Wwws > 301• n ab"Ve, ve ge�afia-y� 'm S 1, �r-- A.; ti2lo • J/ G ` JA qti�14= z�o.-'M () PLANNING CONDITIONS: U 1 Pl.+— —J...I rh. rl.n.,ir„ Dn i.i— (125,771 0:.20) irons Jr.u. Ip A —li, ;., :uY: il-1 lu ateed SOJ.r.I.:, a.l.. �t rilhe .m ,l GII. L.. r... mdcr thr titme lir u.rl l'r.lia). I(_:i.l'a a.L:i.f. �rrq,laO�l l:n avLd i'he.l.li.I,,rrElulaNrr,aa.•iirp t.e..unl.iry111'Adjlra'r11';•�1.ail,a..nia(A]" 1) 1; 1.l'I'I'.1. I.ar.w lion lineI.Y. 1°-I Ileida ol'rod:er.6 cl.drr6rg w,Jl ,;loll o..l a.c„aJ Ilvee lad in do :elArek:ueu. a, I. ...... .:I G.urr lul: M �,n4.'.,,dl to miain.J eisvk. (3) Vl—, ern la" the I'I.amiu,; I)i ai,,iwr lin n I.wA.e;q.a fired In:yenirvam 425.771.01.20. #P20 Critical Areas Checklist CA File No: a° -�58 Site Information (soils/topography/hydrology/vegetation) 1. Site Address/ Location: IS � i '—I S ' Pt-. W , FIB M nA) D- 2. Property Tax Account Number: s nq nGo CX!!) i d i 3. Approximate Site Size (acres or square feet): 4. Is this site currently developed? — yes; —A no. 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). X 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: ; Approx. Depth: 7 Site contains areas of seasonal standing water: What season(s) of the year? 8. Site is in the floodway ; Appiox. Depth: floodplain of a water course. 9. Site contains a creek or an area where water flows across the grounds surface? Flows are year-round? Flows are seasonal? (What time of year? ). 10. Site is primarily: forested ; meadow ;shrubs ; mixed TJ urban landscaped (lawn, shrubs etc) RECEIVED 11. Obvious wetland is present on site: -----For City Staff Use Only 1. Plan Check Number, if applicable? BUILDING DEFT. 2. Site is Zoned? (ZS - 20 3. SCS mapped soil type(s)? ia�, Is--7 3 A FLA—iL, der S ' Z "7 a +�[+K� 5 4i AerwsaA - wb M Im A z. LT (to¢& 4. Critical Areas inventory or C.A. map indicates Critical Area on site? iLi - L-aAAs r" lopt�, 2ra, ,n i1a�.rA 6v+ac� _ �+Kh L W,4At(fc hr•b.m- lrm�vk•hev, Arc. 5. Site within designated earth subsidence landslide hazard area? DETERMINATION ✓ STUDY REQUIRED WAIVER Reviewed by: Date: Critical Areas Checklist/3.25.2004 ATTACHMENT 6 M 1 0 LI `oc_ I09 City of Edmonds Development Services Department Planning Division Phone: 425.771.0220 Fax: 425.771.0221 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 the application 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). R 5 C. E I V 5 D MAY- 0 g 2006 Date Received: = City Receipt #: a� Critical Areas File #: oZ606 0069 -Critical Areas Checklist Fee: $135.00 Date Mailed to Aoolicant: ,J_—,.�J--06 A property owner, or his/her authorized representative, must fill out the checklist, sign and date it, 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. Please submit a vicinity map, along with the signed copy of this form to assist City staff in finding and locating the specific piece of property described on this form. In addition, the applicant shall include other pertinent information (e.g. site plan, topography map, etc.) or studies in conjunction with this Checklist to assistant staff in completing their preliminary assessment of the site. The undersigned applid&*,W stblWjheirs, and assigns, in consideration on 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 part upon false, misleading, inaccurate or incomplete information furnished by the applicant, his/her/its agents or employees. By my signature, I certify that the information and exhibits herewith submitted are true and correct to the best of my knowledge and that I am authorized to file c j on the behalf of the owner as listed below. SIGNATURE OF APPLICANT/AGENT DATE S -Q 4 - n 6 Property Owner's Authorization By my signature, I certify that I have authorized the above Applicant/Agent to apply for the subject land use application, and grant my permission for the public officials and the staff of the City of Edmonds to enter the subject property for the purposes of inspection and postinS atIffg9Wg6is application. 67,IGNATURE OF OWNER PLEASE PRINT CLEARLY Owner/Applicant: Applicant Representative: Name Name -2-osa,st 2 .Ro Street Address Street Address City State Zip City State Zip Telephone: 27 j -O(oc'i(a. Telephone: Email address (optional): lreso4j:VM7W,�Email Address (optional): CITY OF EDMONDS CRITICAL AREAS RECONNAISSANCE REPORT Site Location: 15515 — 751" Place W. Tax Acct. Number: 5009 000 001 01 Determination: Study Required Determination #: CA-06-58 Applicant: Ron Hilliard Owner: Ron Hilliard CRITICAL AREAS RECONNAISSANCE REPORT: STUDY REQUIRED (CA-06-58) During review and inspection of the subject site, it was found that the site may contain critical areas, including Geologically Hazardous areas and Wildlife Habitat pursuant to Chapter 23.40 of the Edmonds Community Development Code (ECDC). 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 submit the entire study with your specific development application. Please review the minimum report requirements for all types of Critical Areas which 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 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 — LANDSLIDE HAZARD AREA It appears that this property contains or is adjacent to a Landslide Hazard Area. • 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). • Landslide Hazard Areas are further defined and illustrated in (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 v 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 2180.050). The alteration must also meet the requirements listed 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. STUDY REQUIREMENT — FISH AND WILDLIFE HABITAT Since the sight is within a mapped wildlife habitat area, the City would like to preserve as much of the native vegetation as possible. DEVELOPMENT PROPOSALS ON A SITE WITH WILDLIFE HABITAT The applicant must submit a clearing/tree cutting plan with any development permit. Tree cutting and clearing of native vegetation shall be limited to the footprint of development. 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. 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. Name nature 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. M ti {yn ti+ t .zT4•^jy�}�i A fi tin r - r J iL r p� '•'• `i .. _tg `.�'�af"` o-�ns'i�,..y{t•.. �'�, d � '?.-'�., t�,,. i1�� • � ~ .cam,. �� k � `rig. � -. - Z xi fiTT"-� a'�k,- C v *�ji, `•.�+ - ^+i _'-�`.��3.�ar'- 3- ,� o-P 7 � -,,ap . � c ` � y� r •�li�tit'�'." r_ i e T � •. �s.��. �r,>A i"i�f� ! �n1� .✓P M'. wr`,.�41."31y+, - ,� 'rr�.'1- �9 �w�� y �t5•_�+. ' %' •, - _ �:R� .�� •fat C7 _ �' �{�,.��.5�'r,r{�ss'°°��` a ;. � t a jj r i ou l< 51 "o ;rl 0 z 0 CD 0 1 D p 0 0 CY) ch :3 CD U) 0 m 0 -0 0 0 = . m U) m -n cr (n l< CL 0 0 Ll 0 0 0 g < Z CD M M m (1). CL 0 0. m X 0 :3 l< 0 0 m w U) (A ID 2Q a (D @D' (A rL E CA B M -4 LT, CD :3 0 0) Fr 0 0 CL cD U) ■T r o, 2.4 m X m M- cl),z ^ C Z -n \� � � � ;C a) ci D 0'A M Cl), M z M co 6 -4 Cornerstone fto Geotechnical, Inc. Consulting Geotechnical Engineers & Geologists September 28, 2009 Mr. Ron Hilliard 6608 — 216th Street SW, Suite 304 Mountlake Terrace, Washington 98043 Geotechnical Final Letter Proposed Single -Family Residence 15515 — 75`h Place West Edmonds, Washington CG File No. 2212 Permit Number 2008-0117 Dear Mr. Hilliard: SEP 3 0 2009 DEVELOPMENT SERVICES CTR- CITY OF EDMONDS This letter summarizes our observations during construction for your residence located at 15515 — 75`h Place West in'Edmonds, Washington. We observed geotechnical aspects of construction on a part-time basis from August 23, 2008 to September 10, 2009. Our observations have been documented in Field Reports 1 through 35. As required by the City of Edmonds, we have observed, and/or provided our evaluation of the following required geotechnical tasks which were outlined in the permit documents: 1. Excavation, Grading, Site Preparation and Shoring We observed grading and excavations within the project site. The excavations were contained within the project site, and shoring was not required. 2. Soil Bearing Verification Project specifications called for the addition of 2 feet of structural fill placed under footings or an approved subgrade. We evaluated the footing subgrade and provided recommendations for overexcavation. We also evaluated the 2 feet of structural fill where used. An allowable foundation bearing pressure of 1,500 psf was used. STREET FILE 17625 —130th Avenue NE, C102, Woodinville, WA 98072 - Phone: 425-844-1977 - Fax: 425-844-1987 Geotechnical Final Letter• • 15515 — 75`h Place West Edmonds, Washington September 28, 2009 CG File No. 2212 Permit Number 2008-0117 Page 2 3. Placement of Fill and Compaction, Proofrolling Fill placement was required under footings for the planned structure as discussed in the soil bearing verification section of this letter. Fill placed was evaluated as meeting requirements. Structural fill was not required elsewhere within the site. 4. Footing Drain, Subdrainage Installation, Foundation Drainage Footing drains were installed around the perimeter of the site and wall drains were observed extending to the footing drains. Our documentation of drainage installation is provided in our letter of April 9, 2009. 5. Temporary Erosion Control and Final Erosion Control We have monitored temporary erosion control during the earthwork phase of site construction. We did not observe significant erosion of material off the site, any erosion observed offsite was promptly cleaned by the contractor. Temporary erosion control measures performed satisfactorily. A final erosion control visit was performed and it appears that surficial soils have been covered with grass or mulch. Final landscaping appears adequate to control erosion. 6. Site Retaining Wall, Debris Walls A tiered block retaining wall was constructed in the northern region of the site. We were onsite during a portion of the construction of the wall. We evaluated wall configuration during construction. Based on our observations and evidence observed in the field, the wall was built according to our recommendations. The east side of the residence is protected from surficial landslides by a debris catchment system. This includes a combination of concrete walls, and the structure framing itself. Upon review of the final construction, it is our opinion that sufficient volume has been created for the design debris event recommended in our report. It is our opinion, based on site observations and testing during construction, the completed development substantially complies with the recommendations in the geotechnical report and with all geotechnical related permit requirements. Although the structure has been designed for a debris event, it is best to use practices that reduce the chance of the debris event from occurring, and if it occurs to reduce the overall size of the event. The concentration of water on the slope is one of the largest contributors of slope instability. We recommend that observations of water flowing from the slope be considered as Cornerstone Geotechnical, Inc. Geotechnical Final Letter • • 15515 — 75 h Place West Edmonds, Washington September 28, 2009 CG File No. 2212 Permit Number 2008-0117 Page 3 on -going slope maintenance. This should be completed during and following large storm events. If drainage flows change, the cause should be investigated and some type of remediation should be completed as necessary. The vegetation on the slope should also be maintained. Any disturbed areas should be replanted with native vegetation. We have consulted with an engineer with experience on steep slopes with a shallow topsoil zone, and he has recommended the future planting of Hazelnut and Dogwood trees. He indicated that they root structure of those trees would help tie the surficial topsoil to the slope. With time, the catchment areas may accumulate slope wash created by raveling or small debris flows. It will be important to maintain these areas free of this material in order to maintain the design catchment volume. We would expect that this could be completed during the summer months, unless a large event occurs. If a large event does occur, the area should be cleaned out in a timely manner. MM Cornerstone Geotechnical, Inc. Geotechnical Final Letter• • 15515 — 75'h Place West Edmonds, Washington September 28, 2009 CG File No. 2212 Permit Number 2008-0117 Page 4 Within the limitations of scope, schedule and budget for our services, we have strived to take care that our services have been completed in accordance with generally accepted practices followed in this region at the time this letter was prepared. No other conditions, expressed or implied, should be understood. We appreciate the opportunity to be of service to you. If there are any questions concerning this letter or if we can provide additional services, please call. Sincerely, Corne_rsopVote nical, Inc. Jeff Wale Project Manager O Q� r � j24 JO I 'q ti AL Charles P. Couvrette, PE Principal Three Copies Submitted JRW:CPC:am cc: City of Edmonds Building Department Steve Barnes — Cornerstone Architectural Group Cornerstone Geotechnical, Inc. Inc 1S°ty July 9, 2009 CITY OF EDMONDS 121 STH AVENUE NORTH • EDMONDS, WA98020 • (425) 771-0220 • FAX (425) 771-0221 Website- www ci edmonds wa us DEVELOPMENT SERVICES DEPARTMENT Planning • Building • Engineering Ron & Susan Hilliard 20831 23`d Ave W Lynnwood, WA 98036 RE: Request for waiver per ECDC 19.10.070 for a small pond 15515 751h Place West, Edmonds Dear Mr. & Mrs. Hilliard, GARY HAAKENSON MAYOR The City is in receipt of your request for waiver to allow installation of a small pond as a landscaping feature at your property currently under construction at 15515 75`h Place W. The site is located in the Earth Subsidence Landslide Hazard Area which is regulated under ECDC Chapter 19.10. Ponds are specifically prohibited in the Earth Subsidence Landslide Hazard Area as set forth in ECDC 19.10.070D unless a waiver is first obtained per ECDC 19.10.070E. Your request for waiver was sent for peer review by our geotechnical consultant, Landau Associates, as permitted in ECDC 19.10.070.E. It is their opinion that the water feature, as it was described in the request to have been constructed, should not have an adverse affect on slope stability as long as it is constructed and maintained properly. A copy of their Technical Memorandum dated June 29, 2009 is attached for your information. Based on the information from your geotechnical engineer and opinion from the City's geotechnical consultant that the subject pond is not likely to trigger or otherwise contribute to any landslide hazard or earth subsidence risk if constructed and maintained properly, it is my determination that the request for waiver for the proposed pond is approved. Please recognize that the presence of this feature and any defects in its design or construction,. or improper maintenance and operation, could expose you as owners to damages or liabilities associated with slope movement that is exacerbated by the failure of this water feature to perform as intended. Sincerely, TVL- Ann Bullis, CBO Building Official STREET FLE • Incorporated August 11, 1890 • Sister Citu - Hekinan. Janan • LANDAU I IPA ASSOCIATES TECHNICAL MEMORANDUM J.I TO: Ann Bullis, Building Official ,:.. City of Edmonds Development Services Department, Building Division FROM: Dennis R. Stettler, P.E. DATE: June 29, 2009 UILO , RE: SUPPLEMENTAL GEOTECHNICAL PEER REVIEW RELATED TO WATER FEATURE BUILDING PERMIT No. 2008-0117 HILLIARD SFR -15515 75TH PLACE WEST EDMONDS, WASHINGTON This technical memorandum provides our geotechnical peer review comments related to a water feature constructed at the Hilliard residence within the Earth Subsidence and Landslide Hazard Area (ESLHA) of North Edmonds. Landau Associates has previously conducted a geotechnical peer review for the project and several supplemental issues, and the results of those previous reviews have been documented in technical memoranda provided to the City of Edmonds (City). The City has issued a building permit and the construction of the residence is largely complete at this time. The current review addresses a water feature that has been constructed on the property that was not a part of the original building permit application package reviewed by the City and Landau Associates. Our services for this task are covered by Task Order No. 09-10 of the On -Call and Emergency/Disaster Response Geotechnical and Environmental Engineering Services Contract between Landau Associates and the City. The project has been constructed within the Earth Subsidence and Landslide Hazard Area of North Edmonds and is required to meet the requirements of Edmonds Community Development Code (ECDC) 19.10 that is applicable to this area. ECDC Section 19.10.070D prohibits the construction of "ponds or other artificial impoundments of water" within the earth subsidence and landslide hazard area because of the critical relationship of groundwater to overall stability of the area and concerns that surface water infiltration or discharge to the ground could adversely impact groundwater levels and slope stability. The water feature that has been constructed on the property is not consistent with the requirements of ECDC Section 19.10.070D. ECDC Section 19.10.070E states that "The prohibitions established in subsection (D) of this section shall apply unless the property owner requests a waiver based upon the written analysis of a geotechnical engineer which clearly establishes that the proposed improvement will have no reasonable likelihood of triggering or otherwise contributing to any landslide hazard or earth subsidence risk either on the site or in the neighboring earth subsidence or landslide hazard area." 130 2nd Avenue South • Edmonds, WA 98020 9 (425) 778-0907 • fax (425) 778-6409 • www.landauinc.com • • Cornerstone Geotechnical, Inc. (the geotechnical engineer of record for the project) has prepared a letter addressing this issue titled: Water Feature Letter, Proposed Ron Hilliard Residence, 15515 7Yh Place West, Edmonds, WA, CG File No. 2212, Building Permit #2008-0117. Prepared for Mr. Ron Hilliard by Cornerstone Geotechnical, dated June 19, 2009. Cornerstone Geotechnical did not directly observed the installation of the water feature, but has relied on information provided by Steve Barnes, the ,project architect, regarding the design and construction of the water feature. Cornerstone Geotechnical states that they were informed that the water feature was constructed with a plastic liner at the base to prevent water from seeping into the onsite soils, and a felt base was placed beneath the plastic liner to provide a cushion. Cornerstone Geotechnical provides their opinion that "the water feature will not adversely affect the stability of the sloping conditions on the site." A water feature that contains a properly designed, constructed, and maintained impermeable liner that prevents any infiltration or discharge of surface water to the ground or groundwater should not have an adverse affect on slope stability. On that basis, the waiver request to allow the water feature to remain appears to be reasonable. The property owner should recognize that the presence of this feature and any defects in its design or construction, or improper maintenance and operation, could expose the owner to damage or liabilities associated with slope movement that is exacerbated by the failure of this water feature to perform as intended. This technical memorandum has been prepared for use by the City in evaluating the requested waiver for the water feature constructed at the Hilliard single family residence at 15515 75"' Place West. The focus of this review was the geotechnical aspects of the request. The purpose of the review was to assess the adequacy of the waiver request for compliance.with City requirements contained in ECDC 19.10 and conformance with conventionally accepted geotechnical engineering practices. This geotechnical peer review by Landau Associates does not lessen the requirements for the applicant's geotechnical consultant, and other design professionals, to prepare an appropriate design for the site conditions. We appreciate this opportunity to be of service to the City. Please contact us if you have any questions or if we may be of further service. DRS/rgm 6/29/09 \\Edmdata\projects\074\144\FileRm\R\WaterFeatureGeotPeerkeview_tm.doc LANDAU AssocIATES 2 RON &- SUSAN HILLIA.RD 20831231d Ave W Lynnwood, WA 98036 Phone (425) 771-0696 Ronh@pacgeoinc.com July 7, 2009 City of Edmonds Patrick Lawler Planning Department Edmonds, Washington Re: Hilliard Residence BLD20090248 - Water Feature Waiver Request Dear Patrick, The purpose of this letter is to request a waiver to allow a water feature to exist at our new home site within the Meadowdale Beach Slide Area. Apparently there has been a lot of discussions concerning this between my architect, Steve Barnes, and City of Edmonds staff. The water feature consists of a small waterfall that flows into a small pond. The water is then recirculated back to the top of the waterfall. The entire feature is lined with an impermeable, heavy duty, rubberized, pond liner. The pond area is approximately 15' long by 3' wide and 9" deep with a trough at the end for a pump. The pond holds roughly 350 gallons. The feature is not plumbed and must be manually filled. am attaching a letter from my geotechnical engineer stating the water feature should have no adverse affect on the slope. I am also including a photo of the feature and some correspondence between the architect and the City. I appreciate your consideration in granting us this waiver allowing the water feature. Sincerely, IJ I 2099 CornerstAe IftwO G eotechn ical, Inc. Consulting Geotechnical Engineers & Geologists June 19, 2009 Mr. Ron Hilliard 6608 - 216'' Street SW, Suite 304 Mountlake Terrace, WA 98043 Water Feature Letter . Ron Hilliard Residence 15515 - 75t' Place West Edmonds, Washington CG File No. 2212 Building Permit # 2008-0117 Dear Mr. Hilliard: JULSO 2) il 01 9 71 CITY OF E3;' '*Nb3 This letter documents our observations and recommendations for the water feature installed at your residence project located at 15515 - 75t' Place West in Edmonds, Washington. We have been requested by Steve Barnes, your architect to complete this letter in compliance with a request from the City of Edmonds. A water feature has been constructed in the northern region of the site, off the northeast corner of the residential structure. We did not observe installation of the water feature, but have been informed by Steve Barnes, the site architect, of the design and construction. The information provided is that the water feature was constructed with a plastic liner at the base of the feature to prevent water from seeping into the onsite soils. A felt base was also placed below the plastic liner to prevent punctures from subgrade conditions. Any punctures to the water feature plastic liner would be expected from tree branches that fall from the slope above the feature. If this occurs, the puncture should be fixed immediately. 17625 -130"h Avenue NE, C102, Woodinville, WA 98072 - Phone: 425-844-1977 • Fax: 425-844-1987 Water Feature Letter Ron Hilliard Residence Edmonds, Washington Building Permit # 2008-0117 June 19, 2009 CG File No. 2212 Page 2 Based on our observations and discussions with Mr. Barnes, it is our opinion that the water feature will not adversely affect the stability of the sloping conditions at the site. Excess water should not be allowed to enter the subgrade soils from punctures within the base of the pond liner. We trust that this letter meets your needs at this time. If you have any questions or need further clarification, please call. Sincerely, Cornerstone Geotechnical, Inc. Jeff Wale Project Manager vi CO P Of \VASF� Fri r I% /17 2oza� `gip �FCiSTER� ti� Charles P. Couvrette, PE Principal Three Copies Submitted JRW:CPC cc: City of Edmonds — one copy Mr. Steve Barnes, Cornerstone Architectural Group — one copy Cornerstone Geotechnical, Inc. i O s) zo' n 1 1 Z z I 20' zo• n ti b Q R cn O� �° z o cn cr o 71 l I I 11 �I o a I 8 I b a i> r^ _ O ' y > Y I:�p^g 1� N88V9'43*W 55.47' (,7 mom$ o � .. O 3 ___--_--____ NSBV9'43'W 148.J2' 3< rn f A I 6 NSSVY'43'W SADI' I i^� C5 IfITT 0 '1y o 0 I i l Big 63 � 3D• � - zo zo• ��86� 8��$ o� N IIo' Bwwwc sETe ACK 1 I I 4rE e .o z 11 r os9 q � eA 156TH ST. SW (UNDEVELOPED) NEW ASPHALT DRM {lr aA'O z z >ri pp Egfi (Tt .571NG PoDNT-Di-WAY Ion b I I IS i 2 Y � A I zo' 20' $ �. $' 2 17 o 82 m T C, ` H ;Z� g� g� sit 22 4 Ng as s ° o� sq� ul A y a 6161 NE 175th Street, Suite 101 ww,A Cornerstone Kenmore, Washington 0 -- 206.682.5.5000 00 ARCHITECTURAL GROUP cornerstonearch.com December 10, 2008 Gina Coccia City of Edmonds 121 5th Ave N Edmonds, WA 98020 Re: Hilliard Residence retaining wall, Permit no. 20080743 Gina: We have made the following changes; 1. Wall has been changed so it is a straight line and does not lie within the 10 foot building setback along 75w Place. See attached site plan. 2. Elevation of wall has been changed to represent new wall placement. See attached. West Elevation. 3. Section through site showing wall is included in this resubmittal. See attached North Elevation. In response to your review comments we have modified the drawings to be sure the wall is not within the western building setback per item I above. We can find no logical reason to not allow the retaining wall to exceed the 3 foot height limit within the northern setback due to the fact that both parcels are owned by the Hilliard's and the northern parcel cannot be developed due to steep slopes. In talking with Duane he suggested that we consolidate the two parcels to. avoid this restriction. The owner was quite taken back by this since this is exactly what he had attempted to do last year but the city suggested he do a boundary line adjustment instead. have no idea what the specific technical reasons were for this recommendation. At this point forcing the owner to go through the time and expense of the property consolidation just to allow the retaining wall to be constructed within the setback between his own parcels is little bit extreme. It appears you could simply allow this due to these. circumstances. The critical areas letter from the geotechnical engineer is included. They are also the engineer of record for the retaining wall. Sincerely,' 11 Steve Barnes Architect DEC 2008 BUILDING DEPARTMEN1 STREET FILE CITY OF EDMONDS p Cornerstone 5 Geotechnical, Inc. Consulting Geotechnical Engineers & Geologists December 2, 2008 Mr. Ron Hilliard 6608 — 216'h Street SW, Suite 304 Mountlake Terrace, Washington 98043 Critical Areas Analysis for the Hilliard Retaining Wall Proposed Single Family Residence 1561h Street Southwest and 75'h Place West Parcel No. 00500900000101 Edmonds, Washington CG File No. 2212 Dear Mr. Hilliard: We have prepared this letter in response to the City of Edmonds letter dated September 24, 2008 in reference to constructing a retaining wall within the site. We have previously addressed geoteclmical aspects of the site in a report prepared January 22, 2007 and a supplemental report prepared February 8, 2008. A TESC plan review letter was prepared, dated April 22, 2008 and we have been evaluating TESC on a weekly basis during the wet season grading timeframe. Design of the fore mentioned wall was provided in a memo dated July 3, 2008. The site has been classified as a critical area because of a steep slope in excess of 40 percent present on the east side of the site. The contractor plans to construct a 7-foot tall retaining wall that will extend north from the northwest corner of the residence and bend towards the east. The City of Edmonds has requested that we evaluate the wall with respect to the city code ECDC 23.80.070.A.2. The code requires that a hazard analysis be conducted within a landslide hazard area and that potential for increased surface water or sediment discharge from the site, slope stability, or other aspects regarding impact to the critical area at question be evaluated. 17625 —130th Avenue NE, C102, Woodinville, WA 98072 • Phone: 425-844-1977 • Fax: 425-844-1987: DEC 112000 STREET FILE BUILDING DEPARniEN D11Y OF EDMONDV Critical Areas Analysis for the Hilliard Retaining Wall 15601 Street Southwest and 75`h Place West Edmonds, Washington December 2, 2008 CG File No. 2212 Page 2 It is our opinion that the addition of the retaining wall in the northwest region of the site will not adversely affect the stability of the site as long as the wall is constructed according to designs we have previously provided. Movement of surface water in that region of the site will be slowed due to the flatter slope inclinations with the construction of the wall and will not direct water off site. The construction of the wall will include compacted backfrll. That backfill will provide additional toe support and decrease the steep slope height in that area. Both of these conditions should lower the risk of sloughing of the lower face. We appreciate the opportunity to be of service to you. If there are any questions concerning this letter or if we can provide additional services, please call. Sincerely, Cornerstone Geotechnical, Inc. WWe Project Manager P. cave r 1��7ny Lh ti�G, Charles P. Couvrette, PE Principal JRW:CPC:am Four Copies Submitted cc: Mr. Steve Barnes, Cornerstone Architectural Group —1 Copy Cornerstone Geotechnical, Inc. Cornerst&e � ft : Geotechnical, Inc. 17625-130th Avenue NE, Suite C102 ♦ Woodinville, WA 98072 Phone 425-844-1977 ♦ Fax 425-844-1987 MEMORANDUM DATE: July 3, 2008 TO: Mr. Steve Barnes FROM: Charles Couvrette, PE RE: Redi-Rock Wall Design Hilliard Residence 1561h Street Southwest and 75th Place West Parcel No. 005 009000010 101 CG File No 2212 This memorandum provides our design of the Redi-Rock retaining wall to be used at the Hilliard residence in Edmonds. The wall is to extend north from the northwest corner of the residence and bend towards the east. This is shown on the current site plan. We understand that the wall will have a maximum height of 7 feet with a near level slope in front. We have developed an in-house spread sheet for the calculation of block wall stability. The spreadsheet determines the lateral loads based on soil strength parameters and geometry. The wall addressed in this letter has a horizontal backslope and a 4 degree batter. We have given the requirement that the fill be well compacted and consist of the on site silty sand soils. We have therefore used an internal friction angle of 34 degrees for our analysis. Using this friction angle and including the 4 degree batter, the equivalent fluid pressure lateral loads were lowered in our spread sheet. We have also included a run with a seismic loading of 5.7 H in our analysis. Our analysis indicates that the wall will meet the minimum stability requirements of 1.5 for sliding and overturning for the static case and 1.15 for the seismic case. We have attached copies of our spreadsheet with this memorandum, in addition to a cross section of the Redi-Rock wall design. We trust that this provides you with the requested information. If you have any questions concerning this memorandum, please contact me. AUG 2 9 2008 BUILDING DEPT. EEC FIDE EXPIRES 6!»lZO1p a� U ^G � U '~ N U _ � ai E cu a O '= AdlllkL N N O 00 0-r, 00ON a)C m 0] co 7FD C O > Cl) 3 N J J y CO 00 O C C Z W T o N N (/1 2 O Q .�J CYi NCO m LL II a �s p o m a _ L 3 o O O U , o p Cn v c Z I 0® U \ � C LL N z Y _ _2 Q Cl O m > V CQ m C) .M. 3 // V n� 0 i p � fvi Y m z _ POU Ao t O m C +,co — a o 2 j o - T v J � v CO J • • Copy of ECOLOGY Version 5 for redi rock.xls LOCK -BLOCK RETAINING WALL DESIGN SPREADSHEET Date: 07/02/2008 File No. 2212 Description: Redi-Rock Design for Hilliard residence. Weight of block material adjusted to compensate for irregular shape and backfilling. Used the weight per block per Redi-rock liturature. This spreadsheet calculates: FS coeff. Of Friction 1.5 >1.5 (typically) FS sliding = 1.5 >1.5 (typically) FS overturning 2 >2 typically) Bearing pressure 2500 = Maximum soil stress (at toe) to check for soil overstress. = Minimum soil stress (at heel) to check for uplift. Assumptions: Friction on base of blocks for FS sliding) = soil friction angle. "Phi". Well drained backfill Fines prevented from infiltering backfill or between blocks. Parameters: Label Radians Beta 86 (degrees) = Wall slope angle (90 for vertical wall B 1.50 Delta 0 (degrees) = Wall to soil friction angle D 0.00 i 0 (degrees) = Backfill slope angle 0 for level) i 0.00 Phi 1 34 (degrees) = backfill friction angle T 0.59 Phi 2 34 (degrees) = foundation friction angle U 0.59 surcharge 50 (psf) = applied from back of block Soil den. 135 (pcf) = soil weight Conc den. 133 pcf) = concrete weight Ka 0.2569" = active earth pressure coefficient Earthquake load= 0 H Wall Geometry (ft) (ft) (ft) (plf) (A (pl ft"ob/If) (ft"ob/If) (ft"ob/If) Block Hgt. Inc. Hgt. cum. Blk thick Blk wt Soil abovE Wgt cum Bx Blk Bx soil Bx cum 1 1.5 1.5 3.39583 677.469 0 677 1150 0 1150 2 1.5 3.0 3.39583 677.469 0 1355 1150 0 2301 3 1.5 4.5 3.39583 677.469 0 2032 1150 0 3451 41 1.5 6.0 3.39583 677.469 0 2710 1150 0 4601 5 1.5 7.5 3.39583 677.469 0 3387 1150 0 5751 6 1.5 9.0 3.395831 677.469 0 4065 1150 0 6902 7 2.5 11.5 3.39583 1129.11 0 5194 1917 0 8819 8 2.5 14.0 3.39583 1129.11 0 6323 19171 0 10736 9 2.5 16.5 3.39583 1129.11 0 7452 1917 0 12653 Notes: X axis is parallel to base of wall. Y axis is parallel to face of wall. "H incr." & "Blk thick" are block dimensions along Y & X axis respectively (input). "Bx blk" = Incremental moment due to block in layer in question. "Bx soil" = moment of soil above "steps' in the wall if " Blk thick"' value changes. Notes: "Pa" = Soil density * Hgt cum * sin (B )^2*Ka/2 "Ps" = surcharge*Ka "N" = W t Cum. *sin B +P*sin D Page 1 Copy of ECOLOGY Version 5 for redi rock.xls "FS sliding" _ (Wt cum * Cos(B + N*Tan U / FScf))/ P*cos(D)) "M resist" = Bx cum*sin(B) +Hgt cum/2*Wgt cum * cos(B) + Blk thick*P*cos(B) "M over" = Hgt cum/3*P*cos(D "FS over" = M resist/ M over "ecc" _ (M over - M resist)/N + Blk thick/2 = ecc of base reaction about CL of base. "Pr max" = N/Blk thick * (1-6*ecc/Blk thick) = Max stress on block in question. "Pr min" = N/Blk thick * (1+6*ecc/Blk thick) =Min stress on block in question. LFSS plf) Plf EQ (plf) (pif) ft*ob/1 (ft*ob/I (ft) (psf) I (ps Pa Ps N I i d ijng M resist M over FS Over ecc. Pr toe Pr heel 39 0 19 676 6.05 1197 34 35.34 -0.02 191 207 155 0 39 13521 3.62 2483 213 11.65 0.02 411 385 3491 0 58 20271 2.59 3858 654 5.901 0.12 721 473 621 0 77 27031 22.01, 5322 1473 3.61 0.27 1182 411 970 0 96 3379 6876 2787 2. 0.491 1853 137 1398 0 116 4055 .39 8519 4713 1.81 0.76 2796 -408 2282 0 148 5181 1.11 11456 9596 1.19 1.34 5135 -2084 3382 0 180 6308 0.92 14641 17039 0.86 2.08 8678 -4963 4697 0 212 7434 0.791 18074 275831 0.66 2.98 13704 -9326 Note: Pr toe should be less MINIMIUM SOIL than allowable and Pr heel BEARING should be greater than zero. Pk Page 2 ! • Copy of ECOLOGY Version 5 for redi rock SEISMIC.xIs LOCK -BLOCK RETAINING WALL DESIGN SPREADSHEET Date: 07/02/2008 File No. 2212 Description: Redi-Rock Design for Hilliard residence. Weight of block material adjusted to compensate for irregular shape and backfilling. Used the weight per block per Redi-rock liturature. SEISMIC This spreadsheet calculates: FS coeff. Of Friction_ 1.5 >1.5 (typically) FS sliding = 1.5 >1.5 (typically) FS overturning 2 >2 (typically) Bearing pressure 2500 = Maximum soil stress (at toe) to check for soil overstress. = Minimum soil stress (at heel) to check for uplift. Assumptions: Friction on base of blocks (for FS sliding) = soil friction angle. "Phi". Well drained backfill Fines prevented from infiltering backfill or between blocks. Parameters: Label Radians Beta 86 (degrees) = Wall slope angle (90 for vertical wall B 1.50 Delta 0 (degrees) = Wall to soil friction angle I D 0.00 i 0 (degrees) = Backfill slope angle (0 for level) i 0.00 Phi 1 34 (degrees) = backfill friction angle T 0.59 Phi 2 34 (degrees) = foundation friction angle U 0.59 surcharge 50 (psf) = applied from back of block Soil den. 135 c = soil weight Conc den. 133 (pcf) = concrete weight Ka 0.2569 = active earth pressure coefficient Earthquake load= 5.7 H Wall Geometry (ft) (ft) (ft) (plf) (plf) (plf) (ft"ob/If) (ft"ob/If) (ft"ob/If) Block Hgt. Inc. Hgt. cum. Blk thick Blk wt Soil abOVE Wgt cum Bx Blk Bx soil Bx cum 1 1.5 1.5 3.39583 677.469 0 6771 1150 0 1150 2 1.5 3.0 3.395831 677.469 0 13551 1150 0 2301 3 1.5 4.5 3.395831 677.469 0 20321 1150 0 3451 41 1.5 6.0 3.395831 677.469 0 2710 1150 0 4601 5 1.5 7.5 3.39583 677.469 0 3387 1150 0 5751 6 1.5 9.0 3.39583 677.469 0 4065 1150 0 6902 7 2.5 11.5 3.39583 1129.11 0 5194 1917---- 0 8819 8 2.5 14.0 3.39583 1129.11 0 6323 1917 0 10736 9 2.5 16.51 3.39583 1129.11 0 7452 1917 0 12653 Notes: X axis is parallel to base of wall. Y axis is parallel to face of wall. "H incr." & "Blk thick" are block dimensions along Y & X axis respectively (Input). "Bx blk" = Incremental moment due to block in layer in question. "Bx soil" = moment of soil above "steps' in the wall if " Blk thick"' value changes. Notes: "Pa" = Soil density * (Hgt cum * sin (B))^2*Ka/2 "Ps" = surcharge*Ka "N" = W t Cum. *sin B +P*sin D Page 1 0 0 Copy of ECOLOGY Version 5 for redi rock SEISMICAs "FS sliding" _ (Wt cum * Cos(B) + N*Tan(U)/ FScf))/(P*cos(D "M resist" = Bx cum*sin(B) +Hgt cum/2*Wgt cum * cos(B) + Blk thick*P*cos B "M over" = Hgt cum/3*P*cos(D) "FS over" = M resist/ M over "ecc" _ (M over - M resist)IN + Blk thick/2 = ecc of base reaction about CL of base. "Pr max" = N/Blk thick * (1-6*ecc/Blk thick) = Max stress on block in question. "Pr min" = N/Blk thick * 1+6*ecc/Blk thick =Min stress on block in question. (plf) Plf EQ (plf) (plf) ft*ob/I (ft*ob/If) (ft) (ps (ps Pa Ps N FS Sliding M resist M over FS Over ecc. Pr toe Pr heel 39 13 19 676 4.95 1197 43 27.52 -0.01 196 202 155 51 39 13521 2.87 2483 290 8.56 0.08 451 345 349 115, 58 2027 2.02 3858 914 4.22 0.25 856 338 621 205 77 2703 A .55 5322 2089 0.50 1502 90 9701 321 96 3379 1.27 6876 3990 1.72 0.84 2478 -488 1398 462 116 4055 .07 8519 6790 1.25 - 1.27 3877 -1489 2282 7541 148 5181 0.85 11456 13930 0.82 2.18 7390 -4339 3382 1117 180 63081 0.701 14641 24860 0.59 3.321 12747 -9032 4697 1552 212 7434 0.601 18074 40385 0.45 4.701 20365 -15987 Note: Pr toe should be less MINIMIUM SOIL than allowable and Pr heel BEARING should be greater than zero. Page 2 STREET FILE CITY OF EDMONDS ,VED TRAFFIC IMPACT ANALYSIS WORK SHEET QCI 2 6 2007 pEaM11 ��NiER Name of Proposed Project: Owner/Applicant: I'C c% &) [A1 L L IAR D Name ZO R Z 1 A.I E mil' Street/Mailing Address Ly Ns It i non WA C11 City d State Zip Telephone: Applicant Contact Person: NEIeVIA , A IMF _� ail 1 Name Street/Mailing City State Zip Telephone: Traffic Engineer who prepared the Traffic Impact Analysis: Firm Name 1. PROJECT DESCRIPTION Contact Name Telephone a. Street address (if known): t� SV Y`'11✓,a l� c�t� r� AL Z1= AL e t-A b. Location: Q.1a �T Lt—t��pS�xt_ (Attach a vicinity map and site plan.) c. Specify existing land use: VA A & Ia: PA VZQE--L- d. Specify proposed type and size of development: '-' t L- �A M I l %4 R E--N Anc N C—E e. When will the project begin construction and when will it be completed? _ G, LZOOR } f. Define proposed access locations: C) P- t U F O ir n ITN 2I �( g. Define proposed sight distance at site egress locations: 0 • L4 2. TRIP GENERATION a. Existing Site Trip Generation Table: PM Peak -Hour Trips Land Use Daily (ADT) IN OUT b. Proposed Project Trip Generation Table: PM Peak -Hour Trips Land Use Daily (ADT) IN OUT c. Net New Project Trip Generation Table: PM Peak -Hour Trips Land Use Daily (ADT) � OUT d. State assumptions and methodology for internal, link -diverted or passby trips: 3. TRIP DISTRIBUTION Prepare and attach a graphic showing project trip distribution percentages and assignments. 4. SITE ACCESS ROADWAY/DRIVEWAYS AND SAFETY a. Have sight distance requirements at egress location been met per AASHTO requirements? b. Intersection Level of Service Analysis • Existing Conditions LOS Delays • Year of Opening LOS Delays • Five Years Beyond Change of Land Use LOS . Delays (Intersections to be evaluated shall be determined by the City of Edmonds Traffic Engineer.) c. Describe channelization warrants: d. Vehicle Storage/Queuing Analysis (calculate 50% and 95 % queuing lengths): 50% • Existing Conditions • Year of Opening • Five Years Beyond Change of Land Use e. If appropriate, state stop sign and signal warrants: f. Summarize local accident history: , (Attach striping plan.) 95% 5. TRAFFIC VOLUMES a. Describe existing ADT and peak -hour counts, including turning movements, on street adjacent to and directly impacted by the project. b. Describe the estimated ADT and peak -hour counts, including turning movements, the year the project is fully open (with and without project traffic). c. Describe the estimated ADT and peak -hour counts, including turning movements, five years after the project has been fully open (with and without project traffic). d. State annual background traffic growth factor and source: 6. LEVEL OF SERVICE ANALYSIS Summarize Level of Service Analysis below and attach supporting LOS analysis documentation. Provide the following documentation for each arterial street or arterial intersection impacted by ten or more peak - hour trips. Other City -planned developments must also be factored into the LOS calculations. Existing LOS: Existing Condition: Year of Opening LOS: With Project: Without Project: • Five Years After Oyenine LOS: With Project: Without Project: Note any assumptions/variations to standard analysis default values and justifications: 7. MITIGATION RECOMMENDATIONS State recommended measures and fees required to mitigate project specific traffic impacts. Traffic impact fee shall be calculated from the Edmonds Road impact Fee Rate Study Table 4 (attached) and as identified in ECDC 18.82.120, except as otherwise provided for independent fee calculations in ECDC 18.82.130. RETURN ADDRESS: City of Edmonds, City Clerk 121 5 th Avenue North Edmonds, WA 98020 CONFORMED COPY 200804141166 5 PGS 0411412008 4:22 m. gg88,00 SNOHOMISH COUNT, ISHINGTON RECEIVED APR 15 2008 BUILDING DEPT. COVENANT OF NOTIFICATION AND INDEMNIFICATION/HOLD HARMLESS Reference Grantor(s): (1)moat u I LLIAP-0 (2) �c t:5Ahl i ILLIA2l%dditional on pg. Grantee(s): City of Edmonds Legal Description (abbreviated): Sec-0!5 _Twn 2--1 M Rng 4 E Qtr_ I W OR Lot Block Plat Assessor's Tax Parcel ID#(s): (1) QOcj[-)ng000b01© 1 (2) i Assessor's Tax Parcel EN not yet assigned CITY OF EDMONDS APPROVED FOR RECORDING BY:.- DATE:=3 AGE I OF c� Under the review procedures established pursuant to the State Building Code, incorporating amendments promulgated by the City of ,Edmonds, and as a prerequisite to the issuance of a building permit for the construction of a residential; structure and attendant facilities, the undersigned OWNERS of property do hereby covenant, stipulate and promise as follows: i J • 1. Description of Subject Property. APPRO-!�R RECO IN BY: ATE PAGE _�y OF This covenant of notification and indemnification/hold harmless relates to a tract of land at the street address of I 1 S _T r_i-T V P L, VT/_ (insert street address), Edmonds Snohomish County, Washington and legally described as: Z. Notification and Covenant of Notification. The above referenced site (hereinafter "subject site") dies within an area which has been identified by the City of Edmonds as having a potential for earth subsidence or landslide. hazard. The risks associated with development of the site have been evaluated by technical consultants and engineers engaged by the applicant as a part of the process to obtain a building permit for the .subject site. The results of the consultant's reports and evaluations of .the risks associated with development are contained in :building. permit file number of-4913601 17 (insert number) on file with the City of Edmonds Building Department. Conditions, limitations, or prohibitions on development may have been imposed in accordance with the recommendations of FAPPRD FOR RECO INDA OF the consultants in the course of permit issuance. The conditions, limitations, or prohibitions may require ongoing maintenance on the part of any owner or lessee or may require modifications to the structures and earth stabilization matters in order to address future or anticipated changes in soil or other site conditions. The statements and conditions proposed by the OWNERS' geotechnical engineer, geologist, architect and/or structural engineer are hereby incorporated by reference from the contents of the file as fully as if herein set forth. Any future purchaser, lessee, lender or any other person acquiring or seeking to acquire an interest in the property is put on notice of the existence of the content of the file and the City urges review of its contents. The file may be reviewed during normal business hours or copies obtained at the Building Department, City of Edmonds, 121 5th Avenue North, Edmonds, Washington 98020. 3. Indemnification and Hold Harmless. The undersigned OWNERS hereby waive any and all liability associated with development, stating that they have fully informed themselves of all risks associated with development of the property and do therefore waive and relinquish any and all causes of action against the City of Edmonds, its officers, agents and employeesarising from and out of such development. In addition, the OWNERS on behalf of themselves, their successors. in interest, heirs and assignees, do hereby promise to indemnify and hold harmless the City' of Edmonds, its officers; agents and employees from any loss, claim, liability or damage of any kind or nature to persons or property either on or off the site resulting from or out of earth subsidence or landslide hazard, arising from or out of the issuance of any permit(s) authorizing development of the site, or occurring or APP BY: D OR TE BY: DATE: PAGE OF arising out of any false, misleading, or inaccurate information provided by the OWNERS, their employees, or professional consultants in the course of issuance of the building permit. 4. Insurance Requirement. In addition to any bonding which may be required during the course of development, the Community Services Director has/has not (strike one) specifically required the maintenance of an insurance policy for public liability coverage in the amount and for the time set forth below in order to provide for the financial responsibilities established through the indemnification and hold harmless agreement above: 5. Covenant to Touch and Concern the Land. This covenant of notification and indemnification/hold harmless touches and concerns the subject tract and. shall run with the land, binding, obligating and/or inuring to the benefit of future owners, heirs, successors and interests or any other person or entity acquiring an interest in property, as their interest may appear. This provision shall not be interpreted to require a mortgagor or lender -to indemnify the City except to the extent of their loss. nor to obligate such persons to. maintain the insurance above required. APPWOA REC INBY:PAF DONE this N day of By STATE OF WASHINGTON ) ss: COUNTY OF ) I certify that I know or have satisfactory evidence that Ron t1. %� arA and \AN\(x� signed this instrument and acknowledged it to be (his/her) free and voluntary act for the purposes mentioned in this instrument. 'aM 7 DATED this 9�" day of L1WCty- bR<- ,-t99- . O rti� 2 4�Sstonc�� F`�,c� NOS Y PUBLIC 1.5-20tt L.\TEMP\BUILDING\MEADOW\COVENANT . sdL2Z44Z-4-7 , NWrARY PUBLIC My commission expires:.(~ - D0 L1 y Cornerstont fto G eotech n ical, Inc. Consulting Geotechnical Engineers & Geologists April 22, 2008 Mr. Ron Hilliard 6608 - 216`h Street SW, Suite 304 Mountlake Terrace, Washington 98043 TESC Plan Review Letter Proposed Single -Family Residence 15515 - 75`h Place West Edmonds, Washington CG File No. 2212 Dear Mr. Hilliard: APR 2 4 20Q8 BUILDING DEPARTMENT CITY OF EDMONDS We have prepared this letter in response to a City of Edmonds Plan Review Comments document dated April 7, 2008. The document concerns your planned residence located at 15515 - 751h Place West in Edmonds, Washington. We have provided geotechnical consultation for the project, including a geotechnical engineering report and several supplemental letters. The April 7, 2008 comments include four required modifications to the TESC plan. The notes on those plan sheets were to be revised to state that native vegetation should be restored in the areas disturbed by tree removal. Another note was to be modified to reflect the requirement that TESC be in place prior to clearing and grubbing. A new note was to be added to state that construction activity is restricted in the Earth Subsidence and Landslide Hazard Area from October 1 through April 1, and references to county were to be changed to reference the City of Edmonds. Another comment states that the geotechnical engineer must document a TESC plan review. One additional comment concerns a soldier pile wall that was planned at one time but is no longer planned to be constructed. We prepared a supplemental letter dated March 26, 2008 that documents the plan changes that made the elimination of the soldier pile wall possible. 17625 -130th Avenue NE, C102, Woodinville, WA 98072 • Phone: 425-844-1977 • Fax: 425-844-1987 TESC Plan Review Letter • Proposed Single -Family Residence 15515 — 75`h Place West Edmonds, Washington April 22, 2008 CG File No. 2212 Page 2 We have been provided with three plan sheets prepared by JC McDonnell Engineering. The sheets include a TESC & Grading Plan, a Drainage/Utilities Plan, and a Notes & Details sheet. The critical portion of the area that will be subject to site disturbance is relatively flat. The steep slope is not to be disturbed, except where trees are to be removed. A silt fence will be installed on the downhill side of the construction area to trap any sediment that may erode from the site. A construction access ramp is planned on the south end of the site, as well as where the driveway will be constructed. This access ramp will be constructed with rock spalls. The designated area for a soil stockpile is located north of the residence. We recommend that soil stockpile and any temporary cuts be covered with plastic to reduce erosion. The required revisions and additions to the TESC notes have been included in the latest plans. It is our opinion that the above described techniques are sufficient for erosion control at the site. As with any erosion control measure, their effectiveness should be evaluated during and following storm events. Any evidence of soil erosion should be used to improve the erosion protection as needed. It is our opinion that the risk of damage to the proposed development, or to adjacent properties, from soil instability will be minimal and the proposed development will not increase the potential for soil movement. The referenced GeoEngineers Landslide Hazard Map indicates that the site is in an area that would be most susceptible to debris slides where failure would be in material that has not previously failed. The probability of movement indicated on the map is between about 2 and 5 percent in 25 years. It is our opinion that the upper 1.25 feet of the soil encountered along the steep slope is loose and most susceptible to movement. The probability of movement of that material is considered much higher than the 5 percent shown on the map. This is noted in our original report and was the basis for our recommended wall heights and debris system. It is our opinion that the wall system will provide the required debris retention and reduce the risk of damage to the structure. It is our opinion that the risk for deep seated slide activity is low, on the order of 2 to 5 percent. This probability estimate is based on the GeoEngineers map. A rigorous probability analysis was not completed for this site, nor is it feasible. If debris slides do occur, cleaning of material behind the wall will likely be needed in order to maintain volume for future slides. We note that yard landscaping will be at risk during a slide event and will require repair or replacing. Cornerstone Geotechnical, Inc. TESC Plan Review Letter • Proposed Single -Family Residence 15515 — 75`h Place West Edmonds, Washington April 22, 2008 CG File No. 2212 Page 3 Within the limits of scope, schedule and budget for our services, we have strived to take care that our services have been completed in accordance with generally accepted practices followed in this area at the time this report was prepared. No other conditions, expressed or implied, should be understood. We appreciate the opportunity to be of service to you. If there are any questions concerning this letter or if we can provide additional services, please call. Sincerely, Cornerstone Geotechnical, Inc. zX lr)� stensen, PE Senior Engineer 1VL07 C�,��`QFCIS'Iti'R� �SIONAL �'�''G�� EXPIRES 61171 ag 1 Charles P. Couvrette, PE Principal Engineer TRC:CPC:am Three Copies Submitted cc: Mr. Steve Barnes - Cornerstone Architecture Cornerstone Geotechnical, Inc. C ornerstse 17625-130th Aver E 02, Woodinville, WA 98072 Phone: 425-844-1977 fto Geotechnical, Inc. Fax: 425-8"-1987 March 27, 2008 Mr. Ron Hilliard 6608 — 216th Street SW, Suite 304 Mountlake Terrace, Washington 98043 RESUB APR 2 4 2008 Seismic Hazard Letter 156`h Street Southwest and 75"' Place West BUILDING DEPARTMENT Parcel No. 00500900000101 CITY OF EDMONDS Edmonds, Washington CG File No. 2212 Dear Mr. Hilliard: You plan to construct a residence at your site at the intersection of 1561h Street Southwest and 75th Place West in Edmonds, Washington. The site has parcel number 00500900000101. We prepared a geotechnical report for the project dated January 22, 2007. That report referenced the sections of the 2003 IBC for seismic hazards. Your consultant, Mr. Steve Barnes, has informed us that the City of Edmonds has adopted the 2006 IBC, and he requested that we prepare this letter to update our seismic hazard to reference the 2006 IBC. This letter should be considered a supplement to our report. It is our opinion based on our subsurface explorations that the Soil Profile in accordance with Table 1613.5.2 of the 2006 International Building Code (IBC) is Site Class D. As referenced in the 2006 IBC, we used the US Geological Survey program "Seismic Hazard Curves and Uniform Hazard Response Spectra." That program uses 2003 NEHRP Seismic Design Provisions to obtain values for Ss, St, Fa, and F,,. The seismic design parameters are: SS 124.2% g S, 43.7% g Fa 1.003 F,, 1.563 SY REET FILE Seismic Hazard Letter • {� 156`h Street Southwest and 75`h Place West Parcel No. 00500900000101 Edmonds, Washington March 27, 2008 CG File No. 2212 Page 2 Site specific coefficients and adjusted maximum considered earthquake spectral response acceleration parameters apply as shown in Section 1613.5 of the IBC. Based on the USGS data and Tables 1613.5.6(1) and (2), the site has Seismic Design Category D. We appreciate the opportunity to be of service to you. If there are any questions concerning this letter or if we can provide additional services, please call. Sincerely, Cornerstone Geotechnical, Inc. CHR�S 3/277/D$ EXPIRES O4125110 Thor Christensen, PE Senior Engineer TRC:RBP:am One Copy Submitted cc: Mr. Steve Barnes — Cornerstone Architectural Group (Three Copies) Cornerstone Geotechnical, Inc. 1�i Cornerstone qV Geotechnical, Inc. March 26, 2008 Mr. Ron Hilliard 6608 — 216`h Street SW, Suite 304 Mountlake Terrace, Washington 98043 17625-130th Ave. NE, C102, Woodinville, WA 98072 Phone: 425-844.1977 Fax: 425-844-1987 Soldier Pile Wall/Minimum Risk Statement Supplemental Letter RESUIS Proposed Single -Family Residence 15515 — 75`h Place West APR 2 41008 Edmonds, Washington BUILDIM3 DEPAMMENT CG File No. 2212 CITY OF EDMONDS Dear Mr. Hilliard: We have prepared this letter in response to the Technical Memorandum dated March 18, 2008 prepared by Landau Associates and additional comments by the City of Edmonds staff. There are three unresolved issues outlined in the Landau letter which we have been requested to address and they include the following: 1. Specify the approximate limits and extent of the recommended soldier pile wall planned to be located in the northeast corner of the residence. 2. Document the conclusion of the conversation between Mr. Chuck Couvrette and Mr. Dennis Stettler on March 11, 2008 pertaining to the correct passive pressure for both standard walls and debris walls. 3. Review of the TESC plans. We have also included a final Geotechnical Declaration and Statement of Risk which addresses the alterations to the project since our last submittal. This was requested in the city staff response. We have previously completed a geotechnical engineering report for the site dated January 22, 2007, a design review letter and minimal risk statement dated December 12, 2007, and a supplemental letter dated February 8, 2008. Each of those documents should be considered part of this review letter. STREET F ILE Soldier Pile Wall/Minimum Risk Statement Supplemental Letter Proposed Single -Family Residence 15515 — 75`h Place West Edmonds, Washington March 26, 2008 CG File No. 2212 Page 2 1. Proposed Soldier Pile Wall The original elevation of the footing in the northeast corner of the planned residence was at 222 feet. After reviewing the topography in the vicinity of that footing, it became clear that the planned 8 foot cut would require shoring. In our Supplementary Letter dated February 8, 2008, we recommended the implementation of a soldier pile wall to stabilize the cut in this area. We have discussed this issue with Cornerstone Architectural Group. The need to shore the cut was eliminated by changing the crawl space on the northwest side of the residence to slab on grade construction. This raised the elevation of the footing in this area to be approximately 18 inches below the slab elevation of 227 feet. The elevation of the toe of the slope in this vicinity is approximately 230 feet. This change in footing elevation will result in a cut of approximately 4 feet deep over relatively short length (a maximum of roughly 5 to 10 linear feet). The edge of the footing is shown to extend to the toe of the slope. We recommend that the slope not be cut into during the preparation of the footing subgrade. This may require the footing to be poured neat, as this would reduce the amount of space required to install the footing. It is our opinion that installing the footing approximately 18 inches below the slab elevation of 227 feet will allow the footing to be installed without the implementation of the soldier pile retaining wall which we have recommended in our Supplementary Letter dated February 8, 2008. If the height of the cut exceeds 4 vertical feet, shoring will be required to stabilize the cut face. 2. Passive Earth Pressures for Standard and Debris Walls We recommend that the equivalent fluid weight to be used in the design for the passive earth pressures for both standard walls and debris walls be 175 pounds per cubic foot (pcf). In our Geotechnical Engineering Report dated January 22, 2007, we recommended that 175 (pco be used for standard walls and that 125 (pcf) be used for debris walls. On March 11, 2008, we discussed the fact that 175 (pcf) shall be used for both wall types with Dennis Stettler of Landau and Associates. This documents that conversation. 3. Review of the TESC Plans On March 19, 2008 we received electronic copies of Sheets 1, 2 and 3 of the TESC plans from Steve Barnes with Cornerstone Architectural Group. Sheets 1 and 3 are dated January 10, 2007, and Sheet 2 is dated March 27, 2007. The critical portion of the area to be subject to site disturbance is relatively flat. The steep slope is not to be disturbed, except where trees are to be removed. A silt fence is shown on the Cornerstone Geotechnical, Inc. 10 j Soldier Pile Wall/Minimum Risk Statement Supplemental Letter Proposed Single -Family Residence 15515 — 750' Place West Edmonds, Washington March 26, 2008 CG File No. 2212 Page 3 down hill side of the construction area to trap sediment being eroded from the site. A construction access ramp is planned on the south end of the site, as well as where the driveway will be constructed. This access ramp will be constructed with rock spalls. The designated area for stockpile is located north of the residence. We recommend that the stockpile and any temporary cuts be covered with plastic to reduce erosion. It is our opinion that the above described techniques are sufficient for erosion control at the site. As with any erosion control measure, their effectiveness should be evaluated during and following storm events. Any evidence of soil erosion should be used to improve the erosion protection as needed. Geotechnical Declaration and Statement of Risk We have prepared this letter as the Geotechnical Declaration and Statement of Risk, as required by the City of Edmonds (ECDC 19.10.040). Our scope of services has included review of our original Geotechnical Engineering Report, dated January 22, 2007, review of the architectural and structural plans by Cornerstone Architectural Group, dated May 7, 2007, review of the Structural Calculations for Hilliard Residence by Peterson, Strehle, Martinson, Inc. Consulting Engineers, dated May, 2007, review of the GeoEngineers, Inc. Landslide Hazard Map, dated July 25, 1984, telephone conversations with Steve Barnes of Cornerstone Architectural Group and David Stubbs of Peterson, Strehle, Martinson, Inc. and review of the updated architectural and structural plans, which were forwarded to our office on December 10, 2007. Additional drawings were shown to us in our office where the crawl space in the northwestern portion of the residence was eliminated and replace with a slab on grade floor. The critical aspect of the geotechnical design is that we have recommended that a wall be constructed to resist forces generated by a debris slide. We recommend that the wall have a minimum height of 12.5 feet. This could be reduced to 10 feet where the debris is deflected laterally or if some overtopping of the wall is acceptable. It could be further reduced where a flat area is available that would increase the captured volume. Where the wall is incorporated into the house, some deflection of the debris is possible and the 10 foot height is appropriate. Where the wall is separate from the house, some overtopping can occur. The updated plans and specifications that we have reviewed conform to the recommendations presented in the original geotechnical report and our letter of December 12, 2007. The basement and debris wall Cornerstone Geotechnical, Inc. '! Soldier Pile Wall/Minimum Risk Statement Supplemental Letter Proposed Single -Family Residence 15515 — 75`h Place West Edmonds, Washington March 26, 2008 CG File No. 2212 Page 4 systems have been designed with adequate heights, per the geotechnidal report. The debris wall structural design calculations have a hand marked correction for the equivalent active fluid pressure at 85 pcf for the loads above the elevation of the future ground surface, as we had recommended. The revised plans also show the recommended debris wall extension to the south, as we had recommended. Provided the construction observation services recommended in the original geotechnical report are implemented, it is our opinion that the risk of damage to the proposed development, or to adjacent properties, from soil instability will be minimal and the proposed development will not increase the potential for soil movement. The referenced GeoEngineers Landslide Hazard Map indicates that the site is in an area that would be most susceptible to debris slides where failure would be in material that has not previously failed. The probability of movement indicated on the map is between about 2 and 5 percent in 25 years. It is our opinion that the upper 1.25 feet of the soil encountered along the slope is loose and most susceptible to movement. The probability of movement is considered much higher than the 5 percent shown on the map. This is noted in our original report and was the basis for our recommended wall heights and debris system. It is our opinion that the wall system, with the plan revisions described herein, will provide the required debris retention and reduce the risk of damage to the structure. It is our opinion that the risk for deep seated slide activity is low, on the order of 2 to 5 percent. This probability estimate is based on the GeoEngineers map. A rigorous probability analysis was not completed for this site, nor is it feasible. If debris slides do occur, cleaning of material behind the wall will likely be needed in order to maintain volume for future slides. We note that yard landscaping will be at risk during a slide event and will require repair or replacing. Within the limits of scope, schedule and budget for our services, we have strived to take care that our services have been completed in accordance with generally accepted practices followed in this area at the time this report was prepared. No other conditions, expressed or implied, should be understood. !.1000 Cornerstone Geotechnical, Inc. Soldier Pile Wall/Minimum Risk Statement Supplemental Letter Proposed Single -Family Residence 15515 — 75`h Place West Edmonds, Washington March 26, 2008 CG File No. 2212 Page 5 We appreciate the opportunity to be of service to you. If there are any questions concerning this letter or if we can provide additional services, please call. Sincerely, Cornerstone Geotechnical, Inc. COUP - .a; 20285 `cSfONAL EY.PIPcg 6117107 Charles P. Couvrette, PE Principal Engineer CPC:am cc: Steve Barnes, Cornerstone Architecture Three Copies Submitted Cornerstone Geotechnical, Inc. F Ir --- f Eowl. 51 • LANDAU ASSOCIATES TECHNICAL MEMORANDUM rrAt1'0d-�Ecawca[Imum nsourEs TO' Jeannine Graf, Building Official City of Edmonds Development Services Department,Building Division FROM: Dennis R. ,Stettler, P.E.. DATE: March 18, 2008 RE: GEOTEcHNICAL PEER REVIEW FOR EARTH SUBSIDENCE AND LANDSLIDE HAZARD AREA SUBMITTAL PACKAGE —PLAN REVIEW NO. PRE20070028 HILLIA RD SFR —15515 75a" PLACE WEST EDMONDS, WASHINGTON This technical memorandum provides our geotechnical peer review of portions of .the permit package submitted tol the City of Edmonds (City) for the proposed referenced development within the Earth Subsidence and 'Landslide Hazard Area (ESLHA) of North Edmonds.. The purpose of' this geotechnical peer review was to.revew portions of the submittal package and assess its compliance with City development. and building permit requirements as ,contained in Edmonds Community Development Code (ECD.C) Chapters 19.10 and 23.80. This geotechnical peer review was.accornplished in accordance with Task Order No. 08-04 of Landau Associates' On -Call Geotechnical Engineering Services Agreement with the City: We.have received the following information forwarded by the.City for review: • Geotechnical Engineering Report, Proposed Single -Family, Residence, 156"' Street Southwest and 75"' Place West, Parcel No. 00500900000101, Edmonds,. VVA, .prepared for Mr. Ron Hilliard :by Cornerstone Geotechnical, dated January 22, 2007. Final Geotechnical Declaration and Statement of Risk-, Proposed Single-Fatruly Residence, 156"' Street Southwest and. 75'1' .Place West, Parcel No. 00500900000101, Echnonds, WA, prepared for Mr. Ron Hilliard by Cornerstone Geotechnical,.dated December 0; 2007. • Supplemental Letter, Proposed Single -Family Residence, 15515'75'r' Place West;; Edmonds; WA, prepared for Mr. Ron Hilliard by Cornerstone Geotechnical, dated February 8, 2008, • Civil Engineering Drawings (3 sheets, including TESC & Grading Plan, Drainage / Utilities Plan, aril Notes aril Details), prepared. by J. C, McDonnell Engineering, PC, dated March 27, 2007. • Site Plan, Survey for Ron Hilliard, prepared by Pacific Geomatic Service, Inc., dated November 9, 2007. • Site Plan, klilliard Residence, 15515 75'h Place W , Edmonds, WA 98026, prepared by Cornerstone Architectural Group, dated May 7, 2007. 130 2nd Avenue South o Edmonds, WA 9B020 0 (425) 778-0907 is fax (425) 778-6409 • www.landauinc:com 0 0 • Letter Re: Hilliard Residence, containing Lead Design Professional Designation and Statement and Architect/Engineer Declaration, prepared by Cornerstone Architectural Group, dated November 9, 2007. • Letter Re: Hilliard Residence, containing Applicant / Owner Liability and Landslide Acknowledgement, prepared by Cornerstone Architectural Group, dated December 18, 2007. • Letter Re: Hilliard Residence 15e Street SW, Edmonds, Washington containing Structural Engineer Declaration, prepared by Peterson Strehle Martinson, Inc., dated December 18, 2007. • Critical Areas Checklist (CA File No. 06-0058) submitted by Mr. Ron Hilliard, dated May 4, 2006. • Storm Drainage Study for Ron Hilliard SFR, prepared by J. C. McConnell & Associates, dated February 1, 2007. • Structural Calculations for Hilliard Residence, Edmonds, Washington (PSM # 07048), prepared by Peterson Strehle Martinson, Inc., dated December, 2007. • Architectural and Structural Plan Set (including Sheets A3.1, A2.1, A2.2, A2.3, A3.2, A3.3, A4.1, A4.2, A4.3, A5.1, A6.1, A6.2, A10.1, SI, S2, S3, S4, S5, S6, and S7) prepared by Cornerstone Architectural Group, dated May 7, 2007. • North Edmonds Earth Subsidence and Landslide Hazard Areas Map (with property location noted) and signed certification as to property location), by Steve Barnes, Architect, dated December 17, 2007. The following sections provide our review comments. GEOTECHNICAL REPORT The geotechnical report prepared by Cornerstone Geotechnical on January 22, 2007 provided a reasonably comprehensive evaluation and discussion of site conditions and risks, and provided geotechnical recommendations for design. However, we noted in our Geotechnical Completeness Review dated January 3, 2008 that the geotechnical report for the project was prepared prior to enactment of Ordinance #3632 that provided for additional requirements related to development in Earth Subsidence and Landslide Hazard Areas. Cornerstone Geotechnical provided a Supplemental Letter dated February 8, 2008 that provides additional geotechnical information and recommendations. In our opinion, the combination of the January, 2007 geotechnical report and the February, 2008 supplemental letter appropriately addresses the requirements of ECDC 19.10 and 23.80 for geotechnical reports. 3/18/08 k\EdmdataXprojects\074\144\FileRm\R\GeotPeerReview_tm.doc LANDAu AssocIATES 2 STRUCTURAL PLANS AND CALCULATIONS Our review of the structural plans and calculations was limited to the aspects related to the geotechnical recommendations. Building Code We note that the geotechnical report, structural calculations, and structural drawings (notes on Drawing SI) all reference the 2003 building code. We understand that the 2006 building code applies to this project. We recommend that the structural and geotechnical documents be updated as appropriate to reflect the requirements of the 2006 code and be referenced as such. Foundations Cornerstone Geotechnical provided recommendations for foundation support, including a recommended allowable soil bearing pressure of 1,500 pounds per square foot (psf). They also recommended that the footing subgrade be over excavated and backfilled with at least two feet of imported, compacted structural fill; that 1 to 2 ft of compacted structural fill be placed beneath slab -on - grade floors; and that the footings be designed to span at least 10 ft. In our opinion, these recommendations are appropriate considering the structure will be supported on shallow foundations above slide debris that provides variable foundation support. It does not appear that the structural engineer has incorporated these recommendations into the structural plans. The "Foundations" note on sheet S1 identifies an allowable soil bearing pressure of 2,000 psf, makes no mention of over excavation and backfill beneath footings or slabs -on -grade, and provides for compaction criteria that is not consistent with the geotechnical report. We recommend that the structural plans be revised to: • Indicate the design allowable bearing pressure of 1,500 psf. • Incorporate the geotechnical engineer's recommendations for over excavation and backfill with imported, compacted structural fill beneath foundations and slab -on -grade floors, and include the geotechnical engineer's recommended criteria for placement and compaction of structural fill. We also recommend that the structural engineer confirm that the foundations are designed to span at least 10 ft. Soldier Pile Excavation Support Cornerstone Geotechnical recommends in their February 8, 2008 Supplemental Letter that a soldier pile wall should be used to support the cut face in the vicinity of the northeast corner of the 3/18/08 \\Edmdata\projects\074\144\FileRm\RkGeotPeerReview_tm.doc LANDAU ASSOCIATES 3 0 0 building. Given the depth of excavation in slide debris at this location near the base of a steep slope, this is a prudent recommendation, in our opinion. This recommendation has not been incorporated into the plans. We recommend that Cornerstone Geotechnical work with the design team to establish the appropriate limits and extent of this recommended soldier pile wall. The soldier pile wall location and details should be clearly shown on the Drawings. We also recommend that the revised Drawings and the soldier pile wall calculations be submitted to the City for review. Debris Walls Cornerstone Geotechnical has recommended that the project include debris walls located along the north and east sides of the house as either a portion of the house foundation wall, a separate retaining wall, or both. We concur with this general recommendation. Landau Associates observed the landslide in the adjacent 1561h Street SW right-of-way that occurred in early January, 1997. The debris slide flowed down the slope and impacted and damaged the garage of the property immediately to the south of the Hilliard property. We are also aware of previous debris slides that have occurred within the vicinity of this project where debris walls have been instrumental in limiting the damage to the residences and have increased the safety of the residents. Cornerstone Geotechnical has made recommendations for debris walls, including potential wall heights as a function of distance from the toe of the slope to achieve reasonable protection from debris slides. The plans show a short concrete debris wall behind the residence, and the structural calculations indicate that walls on the north and east sides of the house have been designed for the higher lateral pressures associated with debris impact as recommended by the geotechnical engineer. Cornerstone Geotechnical states in their December 12, 2007 letter that they have reviewed the structural plans and the basement and debris walls have been designed with adequate heights, per the geotechnical report. In a personal communication between Chuck Couvrette of Cornerstone Geotechnical and Dennis Stettler of Landau Associates on March 11, 2008, Mr. Couvrette also confirmed that he has reviewed the concrete retaining wall designs and they are consistent with the recommendations for debris walls by Cornerstone Geotechnical. The Cornerstone Geotechnical report recommends a passive earth pressure of 175 pcf for design of standard walls and 125 pcf for debris walls. The reason for this difference in passive resistance is not clear and from review of the structural calculations it is apparent that the structural engineer has used 175 pcf in his calculations. In a personal communication between Chuck Couvrette and Dennis Stettler on March 11, 2008, Mr. Couvrette indicated that the correct passive pressure for both wall types should be 175 pcf. We recommend that this correction to the geotechnical report be confirmed in writing by Cornerstone Geotechnical. 3118/08 \\Edmdata\projects\074\144\FileRm\R\GeotPeerReview_tm.doc LANDAU ASSOCIATES 4 Geotechnical monitoring and inspection of earthwork by the Geotechnical Engineer of Record is required, including placement and compaction of structural fill, foundation bearing, temporary shoring, retaining walls, and retaining wall backfill and drainage. The structural plans should note this requirement. CIVIL PLANS The grading plans identify that an estimated 510 cubic yards (yd3) of foundation cut and 303 yd3 of fill will be required for the project. Grading in excess of 500 yd3 requires State Environmental Review and a SEPA Checklist (See "Earth Subsidence and Landslide Hazard Area of North Edmonds Procedures & Permit Submittal Checklist," Item Ta). These documents were not included with the package of review materials that we received. If this has not been submitted, the City should request the applicant complete the SEPA Checklist and submit for review by the City. The TESC and Grading Plan establishes clearing limits that are approximately at the base of the slope and identifies that native vegetation on the slope should be protected. We concur that protection of the native vegetation on the slope is important. Landscaping plans for the area surrounding the house were not included in the plans provided for our review. We recommend that basic landscaping plans for the property be provided that confirm that the steep slope areas will remain protected by native vegetation and that additional cuts, fills, or retaining walls are not planned as a part of landscaping improvements to the property. Several trees have been identified on the slope that are either dead or leaning and the plans call for their removal The TESC and Grading Plan (Construction Sequence item #7) requires that the contractor "Demo and preserve trees as required." The architectural site plan (Sheet MA) calls out the location of six dead or leaning trees on the slope for removal. The January 22, 2007 geotechnical report recommends removing these six trees, as they present a potential hazard to life and structure. The geotechnical report recommends that the trees be cut and removed from the slope, but the root system should be left in place. We concur with this recommendation regarding tree removal. We recommend that the TESC and Grading Plan be revised to more specifically call out the trees to be cut and removed from the slope, with the requirement that the root system be left in place in accordance with the geotechnical report recommendations. In addition, it has been our experience that removing large trees from the slope can result in substantial disturbance to the existing native vegetation on the slope, depending on the method used and care taken by the contractor. The TESC and Grading Plan should also require that the contractor restore native vegetation on the slope as necessary to repair damage to the existing vegetation due to tree removal and provide TESC measures as appropriate for areas of ground disturbance. 3/18/08 \\Edmdata\projects\074%144\FileRm\R\GeotPeerReview tm.doc LANDAU ASSOCIATES 5 The sequence of construction noted on the TESC and Grading Plan needs to be modified to require that the TESC be in place and inspected prior to any construction or site clearing (as currently written, the TESC would be placed after clearing and grubbing, which is not acceptable). The note under Construction Sequence of Sheet 1 regarding the pre -construction meeting needs to be modified to include the Geotechnical Engineer of Record [see City of Edmonds Earth Subsidence and Landslide Hazard Area Temporary Erosion and Sediment Control (TESC) Requirements]. Inspection, maintenance, and regular reporting of TESC measures by the Geotechnical Engineer of Record are required [see the City of Edmonds Earth Subsidence and Landslide Hazard Area Temporary Erosion and Sediment Control (TESC) Requirements]. This requirement should be noted on Sheet 1 and the owner or lead design professional should arrange for these services with the Geotechnical Engineer of Record. The geotechnical report recommends that earthwork be conducted during the drier months. This is consistent with City requirements that earthwork during the winter season between October 1 and April 30 is restricted. We recommend that the TESC and Grading plans specifically indicate that earthwork is restricted between October 1 and April 30 and any earthwork in this time period requires approval from both the Geotechnical Engineer of Record and the City Building Official. REQUIRED STATEMENTS AND DECLARATIONS We reviewed the submittal package to confirm that the various statements and declarations as required by the City for development within the Earth Subsidence and Landslide Hazard Area have been appropriately addressed. • Cornerstone Architectural Group has submitted the required Lead Design Professional Designation and Statement. • Cornerstone Architectural Group has submitted the required Applicant/Owner Liability and Landslide Acknowledgement. • Cornerstone Geotechnical has provided a Final Geotechnical Declaration and Statement of Risk letter dated December 12, 2007 that largely addresses the City requirements. However, the geotechnical engineer has not stated that they have reviewed the erosion and sediment control plans and has not provided a statement regarding the adequacy of the TESC plans, as required by the City. We recommend that this issue be addressed in a supplemental letter or revision to the December 12, 2007 letter. • Cornerstone Geotechnical further described site risks in a supplemental letter dated February 8, 2008 and adequately addressed the site classification and hazard zones as contained in Landau Associates 2007 North Edmonds Earth Subsidence and Landslide Hazard Area Summary Report. In our opinion, the combined December 12, 2007 letter and February 8, 2007 supplemental letter appropriately address the City requirements for Geotechnical Hazard Identification/Declaration and Statement of Risk. 3/18108 \\Edmdata\projects\074\144\FlleRm\R\GeotPeerReview_tm.doc LANDAU ASSOCIATES 6 • Peterson Strehle Martinson, Inc. has submitted the required Structural Engineer Declaration. OTHER ISSUES We noted in our Geotechnical Completeness Review letter of January 3, 2008 that the location of the property marked on the North Edmonds Earth Subsidence and Landslide Hazard Areas Map appears to be incorrect. The property marked is not adjacent to the 156`h Street SW right-of-way. We recommend that the applicant resubmit this plan to the City with the correct location, if they have not already done so. This technical memorandum has been prepared for use by the City of Edmonds in evaluating the adequacy of permit submittal documents related to the proposed Hilliard single family residence at 15515 75`h Place West. The focus of this review was the geotechnical aspects of the application. The purpose of the review was to assess the adequacy of the application documents for compliance with City requirements contained in ECDC 23.80 and ECDC 19.10 and conformance with conventionally accepted geotechnical engineering practices. This geotechnical peer review by Landau Associates does not lessen the requirements for the applicant's geotechnical consultant and other design professionals to prepare an appropriate design for the site conditions. We appreciate this opportunity to be of service to the City. Please contact us if you have any questions or if we may be of further service. DRS/rgm 3/16/08 k\EdmdMa\projects\0741144\FileRm\R\GeotPeerReview_tm.doc LANDAU AssocIATES 7 • 'MEET KE Cornerstone .,y; Geotechnical, Inc, February 8, 2008 Mr. Ron Hilliard 6608 — 2166' Street SW, Suite 304 Mountlake Terrace, Washington 98043 Supplemental Letter Proposed Single -Family Residence 15515 — 750' Place West Edmonds, Washington CO File No. 2212 Dear Mr. Hilliard: INTRODUCTION 17625-1301h Ave. NE, C102, Woodinville, WA 98072 Phone: 425-844-1977 Fax: 425.8444987 lil'1 E S V B APR 2 4 2008 BUILDING DEPARTMENT CITY OF EDMONDS We have prepared this letter in response to a Completeness .Review for Earth Subsidence and Landslide Hazard Area (ESLHA) Submittal Package for your planned residence located at 15515 — 75`' Place West in Edmonds, Washington. The site does exist within the ESLHA. We prepared a geotechnical engineering report for the project dated January 22, 2007. The completeness review prepared by Landau Associates states that our report does not comply with City of Edmonds requirements for the North Edmonds ESLHA that were enacted after our report was prepared. This letter is intended to supplement our report and satisfy the updated City requirements. We have reviewed Chapter 19.10 of the City of Edmonds Municipal Code and the North Edmonds Earth Subsidence and Landslide Hazard Area Summary Report, Edmonds, Washington prepared by Landau Associates dated March 14, 2007. Our original report addresses many aspects of the new code, and we reference that report where possible. Part of the new code requires that research of available.geotechnical reports in the area be completed within 100 feet of the site. The code also requires landslide features within 200 feet of the site be delineated. Since landslide mechanisms in a landslide complex, such as that which exists in the Meadowdale area, can extend some distance, we referenced reports from a larger area than the 100 to 200 foot requirement. A list of reports referenced is attached to this letter. We have also plotted those reports on a Site Area Map, shown in Figure 1. Supplemental Letter Proposed Single -Family Residence 15515 — 75a' Place West Edmonds, Washington February 8, 2008 CG File No. 2212 Page 2 GENERAL DISCUSSION We provided a description of the landslide complex for the Meadowdale area and the site in our report. We provide a brief description herein as a general discussion. The site is located on the eastern edge of the Meadowdale slide complex. The steep slope that exists above the location of the planned residence represents an intact deposit of dense glacially consolidated sediments. This slope represents the back scarp of the large slide complex. The steepness of the scarp causes it to be susceptible to shallow slough type debris slides. We have provided recommendations to accommodate those slides by creating a catchment area at the base of the slope using retaining walls. These walls are designed for high lateral pressures associated with near fluid soils from a shallow slope failure. The structure will be located on top of a slide block that has moved within the complex. We are not aware of any movement of the slide block in recent time, specifically since water levels were Iowered in the slide mass around 1980 by incorporating cut-off drains within the sewer trenches installed in the area. A specific review of the overall slide mass stability, including seismic stability, beyond this qualitative analysis, has not been completed nor is it required by the City of Edmonds code. AREAL MAPPING and GEOTECHNICAL REPORTS Geotechnical Report Review: We completed mapping of the slide complex and known problems based on the geoteclurical reports available for the area. This mapping extends significantly beyond the 200 foot area required by the current code. The results of that mapping are shown on Figure 1 of the Site Area Map. The back scarp of the complex is shown in addition to the location of a known shallow debris slide. The area west of the scarp line is either the scarp itself, or is occupied by the blocks that make up the overall slide complex. Other than the shallow debris slide, the reviewed geotechnical reports did not identify active slide movements or conditions that would threaten development on the subject site. The only geotechnical investigation that identified a specific slide was by Hemphill (1997) on the site immediately to the south, 15605 — 75s' Place West. That was a short letter that identified a debris slide that occurred on or near the 156s Avenue West right-of-way. Hemphill determined that it was a very shallow event and that very dense soils were exposed in the resulting face that he considered stable. Hemphill did not determine the specific cause of the slide, but suggested that it could have been due to leaking drain pipes originating from residences above. Those pipes were exposed and appeared to have been repaired at the time of his visit.' We used the scar from the face of this slide as a basis for our Cornerstone Geotechnical, Inc. Supplemental Letter Proposed Single -Family Residence 15515 — 756' Place West Edmonds, Washington February 8, 2008 CG File No. 2212 Page 3 expected future debris slide that could occur above the planned residence on this project. This scar depth corresponded to the depth of loose soil we probed when we climbed the face of the slope. The approximate location of this slide is shown on the Site Area Map. The geotechnical reports west of 75g' Place did not identify specific recent movements. The AESI (1997) report for the 15604 address described distress in an existing structure, that was dated prior to the installation of cut-off drains discussed above. Each of those reports stated that the overall stability of the landslide complex was not known and that the evaluation of the current stability is mainly based on recent (post 1980) performance and improvements made by lowering the ground water table. Those reports also addressed the steepened toe area of the slide complex. Site Reconnaissance Following Report Review: After obtaining the geotechnical reports, we completed a site visit and walk -over while observing the surrounding areas, extending north on 75s' Place north into the Lunds Gulch Park to the northern extent of the scarp, and south of the subject site about 5 lots. We then accessed the toe of the overall slope along the railroad grade and beach. Although we observed signs of past movements, we did not observe any signs of on -going (post 1980) movements. We did not observe signs of seepage from the toe of the slide complex within the area immediately downslope of the project site. We did observe water flowing in a catch basin, shown on the Site Area Map. This was not immediately following a rain event. We suspect that the water flow observed was from the sewer line cut-off drains discussed above. The flow was estimated to be on the order of 1 gallon per minute (gpm). CLASSIFICATION OF SITE WITH RESPECT TO THE LANDAU REPORT We have classified the site as a Zone C area in accordance with the "North Edmonds Earth Subsidence and Landslide Hazard Area Summary Report'; by Landau Associates; dated March 14, 2007. We used Figure I of that report to identify hazards that need to be considered based on that zone classification. We list each consideration for that zone and our assessment in the bullet list below: o Zone C is subject to potential debris flow of outwash sands from above the Whidbey Formation contact which is shown in Zone D. Those flows require a significant thickness of ground water. We did not observe any indication of ground water seepage at the contact of these two units Cornerstone Geotechnical, Inc. Supplemental Letter Proposed Single -Family Residence 15515 — 75`h Place West Edmonds, Washington February 8, 2008 CG File No. 2212 Page 4 above the site. Therefore, we do not consider the debris flow to be a viable failure mechanism on this site. • Shallow debris slide derived from the face of the bluff. This failure mechanism was considered in our analysis and our report provides recommendations for the required catchment volume and loads for retaining walls that will provide this catchment. Some of these walls are included within the structure. We do not expect these slides to continue off site. • Large scale slope instability would be derived from large movements within the landslide mass. Development within the Meadowdale Landslide Complex assumes that the overall deep seated landslide mass is stable. This is based on recent historic data and the improvements created when the cut-off drains were installed. To our knowledge, an engineered factor of safety has not been determined for this mechanism nor has any impact due to a design seismic event been considered. These are part of the accepted risks associated with development within the Meadowdale Landslide Complex area. • The landslide mass of Zone C can have loose zones that are susceptible to settlement and local slope instability. We encountered reasonably dense soils in our test pits indicating that the surficial soils on site consist of an older colluvium. Our visual evaluation of the colluvium indicates that it should be suitable for foundation support. However, by definition, the colluvium can vary in consistency due to the way it was deposited. Therefore, we recommended in our report that the structure be designed to resist differential settlements. Since piles are not being used, the connections for underground utilities to the structure are not as critical. If there is settlement, it would be expected to be areal (within and outside of the building footprint). It is more critical if the utilities cross from soils that could undergo some potential settlement to a pile supported structure. AIthough not required, we do consider it good practice to include some flexibility in the utility connections in this environment. BLUFT, RETREAT The bluff above the site will be subject to bluff retreat. This retreat is associated with the shallow debris slides that we have discussed and for which we have provided design recommendations in our report. There are some sizable trees on the slope that indicate that the face of the slope has been stable for over Cornerstone Geotechnicai, Inc. Supplemental Letter Proposed Single -Family Residence 15515 — 75'h Place West Edmonds, Washington February 8, 2008 CG File No. 2212 Page 5 40 years. We suspect that the actual time is in excess of 40 years. However, based on a slide depth of 1.5 feet (current depth of loose soil on the slope) every 40 years, we would expect a bluff retreat rate of on the order of 1 foot in 25 years and 5 feet within 100 years. Catastrophic events such as earthquakes could be expected to impact the timing of individual shallow events, but not significantly increase the rate of retreat over the long term. As discussed above in the Classification section, the debris created by the retreat process is accommodated in the design of the structure. We note that following a slide event, the debris needs to be removed from behind the house to maintain available volume for the next event. GROUND WATER We did not encounter ground water in our excavations. We also did not observe seepage immediately down slope of the site. We therefore consider that ground water levels at the site are below a depth where intercepting to increase stability is feasible. We also do not expect that the excavation for the structure will encounter a ground water table. Depending on the time of year, some localized ground water may be encountered, but this is expected to be limited. PLAN REVIEW We completed a plan review letter dated December 12, 2007 for this project. It is our opinion that the comments regarding stability and the impact of the project on the site presented in the plan review letter are still applicable to the project and that the project has been designed in accordance with the recommendations provided in our report. We did not provide information in this supplemental letter that would change the opinions stated in our plan review letter. We do note one construction condition that was not addressed in our plan review. The northeast corner of the building will be cut into the toe of the slope. It would be a significant disturbance to the slope to use cut slopes for worker safety. Therefore, we recommend that a soldier pile wall be used to support this local cut face. Recommendations for soldier pile walls may be found in our report. CLOSURE This letter has been written for Mr. Ron Hilliard and his representatives for design and understanding of this project. This letter should be considered a supplement to our original report and should be attached Cornerstone Geotechnical, Inc. Supplemental Letter Proposed Single -Family Residence 15515 — 75`h Place West Edmonds, Washington February 8, 2008 CG File No. 2212 Page 6 to that report. The intent of this letter is to provide input required by the new City of Edmonds ESLHA code. Within the limitations of scope, schedule and budget for our services, we have strived to take care that our services have been completed in accordance with generally accepted practices followed in this area at the time this report was prepared. No other conditions, expressed or implied, should be understood. . .•. Cornerstone Geotechnical, Inc. Supplemental Letter Proposed Single -Family Residence 15515 -- 750i Place West Edmonds, Washington February 8, 2008 CG File No. 2212 Page 7 We appreciate the opportunity to be of service to you. If there are any questions concerning this report or if we can provide additional services, please call. Sincerely, Cornerstone Geotechnical, Inc. Donald W. Tubbs, PhD., L.E.G. Consulting Engineer Geologist Charles P. Couvrette, PE Principal Engineer TRC:CPC:am List of References One Figure Three Copies Submitted Cornerstone Geotechnical, Inc. Supplemental Letter Proposed Single -Family Residence 15515 — 75'h Place West Edmonds, Washington February 8, 2008 CG File No. 2212 Page 8 LIST OF REPORTS REVIEWED FOR THIS STUDY "Geotechnical Evaluation"; Dennis M. Bruce; June 1,1999; 15615 — 75'h Place West "Additional Geotechnical Criteria"; Dennis M. Bruce; August 26, 1999; 15615 — 75'h Place West "Preliminary Geotechnical Engineering Report"; Associated Earth Sciences, Inc.; October 24, 1997; 15604 — 75°1 Place West; Aldridge Short Plat "Cylinder Pile Retaining Wall"; Associated Earth Sciences, Inc.; January 18, 2000; 15604 — 75'h Place West; Aldridge Short Plat "Critical Areas Checklist"; City of Edmonds; June 14,1995; 15604 — 751h Place West "Geotechnical Engineering Report"; Associated Earth Sciences; October 24,1997; 15604 75'h Place West; Aldridge Short Plat "Revised Geotechnical Report"; Shannon & Wilson; January 26, 1994; 15620 — 75`h Place West "Subsurface Exploration, Geologic Hazard, and Geotechnical Engineering Study"; Associated Earth Sciences; October 27, 2005; 15625 — 75'h Place West "Geotechnical Report"; Shannon & Wilson; March 29, 1990; 15620 — 751h Place West "Critical Areas Checklist"; City of Edmonds; March 31, 1993; 7222 —156'h Street SW "Subsurface Exploration, Geologic Hazards, and Geotechnical Report"; Associated Earth Sciences, December 31, 1991, 7222 —156" Street SW "Investigation of Slide and Garage Damage"; Letter; Hemphill Consulting Engineers; May 25, 1997,15605 — 75'h Place West, Meadowdale "Geotechnical Engineering"; Hemphill Consulting Engineers; December 10, 1990; 15631— 75'h Place West, Spiro Residence "Mezich Lot —Addendum to November 13, 1989 Letter"; Cascade Geotechnical, Inc.; April 13, 1990; 7215 —156" Street SW "Geotechnical Engineering Study"; Ten -a Associates, Inc.; July 28, 1990; 15520 — 751h Place West "North Edmonds Earth Subsidence and Landslide Hazard Area Summary Report"; Landau Associates; March 14, 2007 Cornerstone Geotechnical, Inc. ca 2 z ca 0 3 L � (6 m 0 z (n W u m '2 N Co r CD eet} m W C W Q m s O 00 8 tCD o N C N m U O .�. W .m5 O In os 46 rL d N N 0 h ttTTii C G N a o $ �•- ' O X C N ry D N 7 l! GD pp coto G to t0 w ' N V � W co CM tll c� at Is t m o S e u3 p z z o a 32 m 2 5 9 O .c �$F F m CjIN ur g cm e-d �S 3N c m' mm S z3 y H dNz C w3 w •- V at S C�N t ij 0- c93 b)c 22 w 0o C UJE cm v E r rn� Q c Mz g 0 3 s m 8 o$ m �rL m of if w oco m mr �v w m y d U8 r u5U ma m 8 m m o mm a M 8 m v L a c d °� �,o U a y -� :�a ?a z� ECD V— Qom• ca ic a � m �o= �i ar � 1r _ s� g l l I I ;_ 1 1 OV08 HOVq S,ONIII//d 000ld 419L I _ I I �� / J! CO i m 0 m� \ $ d 1146 • Cornerstone VAO Geotechnical, Inc. December 12, 2007 Mr. Ron Hilliard 6608 — 2160' Street SW, Suite 304 Mountlake Terrace, Washington 98043 17625-1301h Ave. NE, C102, Woodinville, WA 98072 Phone: 425-844.1977 Fax: 425-844-1987 Final Geotechnical Declaration and Statement of Risk Proposed Single Family Residence 1561h Street Southwest and 751h Place West Parcel No. 00500900000101 Edmonds, Washington RECEIVED CG File No. 2212 DEC 18 2007 Dear Mr. Hilliard: BUILDING DEPT. We have prepared this letter as the Geotechnical Declaration and Statement of Risk, as required by the City of Edmonds (ECDC 19.10.040). Our scope of services has included review of our original Geotechnical Engineering Report, dated January 22, 2007, review of the architectural and structural plans by Cornerstone Architectural Group, dated May 7, 2007, review of the Structural Calculations for Hilliard Residence by Peterson, Strehle, Martinson, Inc. Consulting Engineers, dated May, 2007, review of the GeoEngineers, Inc. Landslide Hazard Map, dated July 25, 1984, telephone conversations with Steve Barnes of Cornerstone Architectural Group and David Stubbs of Peterson, Strehle, Martinson, Inc. and review of the updated architectural and structural plans, which were forwarded to our office on December 10, 2007. The critical aspect of the geotechnical design is that we have recommended that a wall be constructed to resist forces generated by a debris slide. We recommend that the wall have a minimum height of 12.5 feet. This could be reduced to 10 feet where the debris is deflected laterally or if some overtopping of the wall is acceptable. Where the wall is incorporated into the house, some deflection of the debris is possible and the 10 foot height is appropriate. Where the wall is separate from the house, some overtopping can occur. Proposed Single Family Residence — Geotechnical Declaration and Statement of Risk 156"h Street Southwest and 75`h Place West Edmonds, Washington December 12, 2007 CG File No. 2212 Page 2 The updated plans and specifications that we have reviewed conform to the recommendations presented in the original geotechnical report and our letter of December 6t . The basement and debris wall systems have been designed with adequate heights, per the geotechnical report. The debris wall structural design calculations have a hand marked correction for the equivalent active fluid pressure at 85 pcf for the loads above the elevation of the future ground surface, as we had recommended. The revised plans also show the recommended debris wall extension to the south, as we had recommended. Provided the construction observation services recommended in the original geotechnical report are implemented, it is our opinion that the risk of damage to the proposed development, or to adjacent properties, from soil instability will be minimal and the proposed development will not increase the potential for soil movement. The referenced GeoEngineers Landslide Hazard Map indicates that the site is in an area that would be most susceptible to debris slides where failure would be in material that has not previously failed. The probability of movement indicated on the map is between about 2 and 5 percent in 25 years. It is our opinion that the upper 1.25 feet of the soil encountered along the slope is loose and most susceptible to movement. The probability of movement is considered much higher than the 5 percent shown on the map. This is noted in our original report and was the basis for our recommended wall heights and debris system. It is our opinion that the wall system, with the plan revisions described herein, will provide the required debris retention and reduce the risk of damage to the structure. It is our opinion that the risk for deep seated slide activity is low, on the order of 2 to 5 percent. This probability estimate is based on the GeoEngineers map. A rigorous probability analysis was not completed for this site, nor is it feasible. If debris slides do occur, cleaning of material behind the wall will likely be needed in order to maintain volume for future slides. We note that yard landscaping will be at risk during a slide event and will require repair or replacing. Within the limits of scope, schedule and budget for our services, we have strived to take care that our services have been completed in accordance with generally accepted practices followed in this area at the time this report was prepared. No other conditions, expressed or implied, should be understood. Cornerstone Geotechnical, Inc. Proposed Single Family Residence — Geotechnical Declaration and Statement of Risk 156`' Street Southwest and 75`h Place West Edmonds, Washington December 12, 2007 CG File No. 2212 Page 3 We appreciate the opportunity to be of service to you. If there are any questions concerning this letter or if we can provide additional services, please call. Sincerely, Cornerstone Geotechnical, Inc. 1 Sean L. Caraway, PE Senior Engineer c o �� y _ t y ` Z I.2/r2�0'j 20285 SIONALG` EXPIRES 61171 01 Charles P. Couvrette, PE Principal SLC:CPC:am Four Copies Submitted cc: Mr. Steve Barnes, Cornerstone Architectural Group — 1 Copy Cornerstone Geotechnical, Inc. PETERSON .)TREHLE P ARTINSON, INC. CONSULTING ENGINEERS December 18, 2007 Steve Barnes Cornerstone Architectural Group RE: Hillard Residence 1561h Street SW Edmonds, Washington Steve: Structural Engineer declaration: We have reviewed the geotechnical report and understand its' recommendations, have explained to the owner the risk of loss due to slides on this site and have incorporated into the design the recommendations of the geotechnical report and designed in measures to reduce the potential risk of injury or damage that might be caused by any earth movement predicted in the report. Sincerely, PETERSON STREHLE MARTINSON, INC. M. David Stubbs, PE, SE � ,�lIQ -7141< Vice President RECEIVED DEC 1 8 2007 BUILDING DEPT. 2200 SIXTH AVENUE, SUITE 601 PHONE 206-622-4580 SEATTLE WASHINGTON 98121 FAX 206-622-0422 ,.� CORNERSTONE ARCHITECTURAL GROUP November 9, 2007 City of Edmonds Re: Hilliard Residence To Whom It May Concern: Lead Design Professional Designation and Statement: Steve Barnes with Cornerstone Architectural Group shall be the lead design professional for the applicant. We have reviewed the geotechnical report and understand its' recommendations and have incorporated into the design the established measures to reduce the potential risk of injury or damage from any earth movement predicted in the report. Architect/Engineer declaration: We have reviewed the geotechnical report and understand its' recommendations, have explained to the owner the risk of loss due to slides on this site and have incorporated into the design the recommendations of the geotechnical report and designed in measures to reduce the potential risk of injury or damage that might be caused by any earth movement predicted in the report. Sincerely, 8954 ' y3 Steve Barnes ST N A. BA NES a1:i+��j. i,V�"YYiS✓.r...1::.v;'rA RECEIVED D E C O 8 2007 BUILDING DEPT. 1904 THIRD AVENUE SUITE 500 SEATTLE, WASHINGTON 98101 206.682.5000 TEL 206.621.7717 FAX WWW.CORNERSTONEARCH.COM 0 CORNERSTONE ARCHITECTURAL GROUP December 18, 2007 City of Edmonds Re: Hilliard Residence To Whom It May Concern: Applicant/Owner liability & landsclide acknowledgement: The accuracy of permit submittal information is warranted by the applicant and relieves the City and it's staff from any liability associated with reliance on such permit application submittals. All conclusions referenced in submitted reports shall be those of the applicant and associated design professionals. The applicant and owner understand and accept the risk of developing in an area with potentially unstable soils and understand the required temporary and permanent erosion control and site maintenance issues associated with specific geologic hazards or conditions of the site that may affect slope stability over time. The owner will advise, in writing, any prospective purchaser of the site, or any prospective lessees of structures on the site, of the slide potential and on -going maintenance issues of the area on the property. Sincerely, RECEIVED DEC 18 2007 BUILDING DEPT. Steve Barnes 3954 iLc , a� EVEN SA R ES STREET FILE 1904 THIRD -AVENUE SUITE 500 SEATTLE, WASHINGTON 98101 206.682.5000 TEL 206.621.7717 FAX WWW.CORNERSTONEARCH.COM CITY OF EDMONDS 121 5TH AVENUE NORTH - EDMONDS,WA 98020 PHONE: (425) 771-0220 - FAX: (425) 771-0221 "C. 1 ri� *PERMIT MUST BE POSTED ON JOBSITE* STATUS: ISSUED ENG20080276 SIDE SEWER PERMIT (I -Single Fainily) I Permit Number: ENG20080276 Expiration Date: 7/18/2009 Job Address: 15515 75TH PL W, EDMONDS STEVE BARNES GREENWALK DEVELOPMENT LLC 1904 3RD AVE, SUITE 500 12733 39TH AVE NE SEATTLE, WA 98101 SEATTLE, WA 98125 206-367-2797 LICENSE #: GREENDL955NS EXP: 8/10/2009 N N O' DLSCIZIPTION REPAIR N PROPOSE TO REUSE LATERAL LID NUMBER GRINDER PUMP N PROPOSE TO REUSE SIDE SEWER SS FOR NEW SFR N N EASENIENTINFORNIATION PROJECT CROSSES OTHER PRIVATE PROPERTY VERIFICATION OF RECORDED EASEMENTS COMPLETE 1NDEMATTY.- The Applicant has signed an application which states he/she holds the City of Edmonds harmless from injuries, damages or claims ofany kind or description whatsoever, foreseen or unforeseen, that may be made against the City of Edmonds or any ofits departments or employees, including but not limited to the defense ofany legal proceedings including defense costs and attorney fees by reason ofgranting this permit. CALL DIAIrA-DIG (1-800-424-5555) BEFORE ANY EXCAVATION CALL FOR INSPECTION (425) 771-0220 EXT.1326 24 HOUR NOTICE REQUIRED FOR ALL INSPECTION REQUESTS THIS APPLICATION IS NOT PERMITUNTIL SIGNED BY THE CITY ENGINEER OR HIS/HER DEPUTY: AND FEES ARE PAID, AND RECEIPT IS ACKNOWLEDGED IN SPACE PROVIDED. _Printed: Thursday. July 17, 20C RELEASED BY ❑ F LECOPY INSPECTOR COPY RFAPPLICANT COPY STATUS: ISSUED ENG20080276 • Restore ROW to City standards • Restore Landscape to like or better conditions. • Call for locates of underground utilities prior to any excavation. • Alert affected residents and/or businesses prior to work start. • Conform to approved working drawings and Traffic Control plan. • Public utilities maintain 5' separation from City Utilities. • Verify clear bore crossings • Utility patch restoration to be in accordance with Edmonds Standard detail E2.3 • CDF is required for trench bacldill. Refer to Edmonds Standard Detail FA.4 • Maintain erosion & sedimentation control. Keep street clean. • Construction hours are Monday -Friday 7am-6pm and Saturdays 10am-6pm No work on Sundays or Federal Holidays. • Call for required inspections as noted. • Applicant shall repair/replace all damage to utilities or frontage improvements in City right-of-way per City standards that is caused by or occurs during the pemutted project. • &Sanitary Side Sewer Inspection • &Engineering Final PARTIAL INSPECTION DATE: INITIAL: NOTES: PARTIAL INSPECTION DATE: INITIAL: NOTES: FINA L TNSPEC71ON APPROVED DATE: INITIAL: RECEIVED J. C. Mc DONNELL & ASSOCIATES CONSULTING CIVIL ENGINEERS P.O. Box 13199 Mill Creek, WA. 98082 GRADING QUANTITIES REPORT For RON HILLIARD SFR Located at 156th & 751h Place West Edmonds, WA. 98020 DEVELOPER: Mr. Ron Hilliard, PLS 20831 23rd Avenue W Lynnwood, WA. 98036-7804 Issue Date: April 21, 2008 Revision Date: June 26, 2008 PREPARED BY: J. C. McDonnell, PE Surveyor of Record: PGS Inc. 6608- 2161h Street SW Ste 304 Mountlake Terrace, WA 98043 Tel:(425) 778-5620 JUN 2 7 2008 Ur,gjy O FE0 NDS l JUN 2 7 2008 DEVELOPMENT SERVICES CTR. CITY OF EDMONDS 6"iREET FIDE 1 I r Y.i111111"UM, By direction of the Project Architect, the Grading on this Project has been reduced by raising the Floor elevations to reduce the Foundation Cut and by minimizing disturbance to the ground elevations surrounding the house. The basement floor has now been raised from 517.0 to 518.0 in order to reduce the foundation cut by 44.44 cubic yards. This adjustment was necessary as a result of a revised footing calculation, which increased the foundation cut quantity by 42 Cubic Yards. This is a quantity correction for the over excavation of the lower footings as directed by the City of Edmonds. The impact of this change is addressed on the following pages. The basement floor is raised to maintain the total project Cut Quantity below 500-Cubic Yards. The driveway alignment will be modified slightly as a result of this change to maintain a safe driveway grade.. J.C.McDonnell Engineering, PC RON HILLIARD SURFACE GRADING QUANTITIES (Manual Calculation) SECTION A 1 (FILL) SA = 544.8 SF AVERAGE DEPTH = 80.9/32PNTS = 2.52 FT FILL - 0.33' PAVEMENT = 2.22FT Al FILL VOLUME = 2.22 FT * 544.8 FT^2 = 1,209.46 CF/27= 44.8 CY SECTION Al (CUT) SA = 56.75 SF AVERAGE DEPTH= 6.3 / 4 = 1.58 LF Al CUT VOLUME = 1.58 FT * 56.8 FT^2 = 189.46CF/27= 3.31 CY SECTION A2 (FILL) SA = 185 SF AVERAGE DEPTH = 3.7/12PNTS = 0.308 A2 FILL VOLUME = 0.308FT * 185 FT^2 = 57.04 CF/27= 2.11 CY SECTION A2 (CUT) SA = 270 SF AVERAGE DEPTH= 38.6 /20 = 1.93 LF Al CUT VOLUME = 1.93 FT * 270 FT^2 = 521.1 CF/27= 19.3 CY SECTION A3 ASSUME 12" DUFF OVER THE AREA REPLACED W SOD SA = 376 SF A3 CUT = FILL = (1.0 FT * 376 SF) / 27 = 13.8 CY SECTION A4 (F I L I_) SA = 290 SF AVERAG F DEPTH = 7.9 /14PNTS = 0.56 + 0.5 ASSUMED =1.06 A4 FILL VOLUME = 1.06FT * 290 FT^2 = 307.4 CF/27= 11.38 CY SECTION A4 (CUT) SA = 290 SF A4 CUT VOLUME = 0.5 DUFF * 290 FT^2 = 145 CF/27= 5.4 CY SECTION A5 (FILL,) CUT = FI LL = 1-FOOT SA = 587 SF A5 FILL. VOLUME = LOFT * 587 FT 2 = 587 CF/27= 21.74 CY SECTION A5 (CIJT) SA = 5S7 SF A5 CUT VOLUME = 1.0 DUFF * 587 FT^2 = 587 CF/27= 21.74 CY SECTION A6- SWALE (FILL) SA = 0.86 SF A5 FILL VOLUME = 21.OFT * 0.86 FT^2 = 18.7 CF/27= 0.69 CY RON HILLIARI) LOT GRADING (OUTSIDE FOUNDATION) FILL = 95.52 CF CUT = 63.66 CV J.C.McDonnell Engineering, PC FOUNDATION EXCAVATION CALCULATIONS (By ACAD LDD 2007 Methods) GRID Current stratum: I-IOUSE_DIG Site name = HOUSL_DIG Cut = 373 yards fill = 2 yards Net = 371 yards CUT PRISM Displaying strata report for stratuin: HOUSE —DIG Cut: 390 yards 171II: 84 yards Net: 307 yards (CUT) Average of two methods of Calculation = 382 Yards (CUT) GRADING TOTALS CUTS (CY) FILLS (CY) SITE GRADING (by grid area method) 63.66 95.52 FOUNDATION (by ACAD LDD) (Basement des i;;n elevation has been raised 1-foot) 382.0 43.0 ADJUSTMENT _FOR LOWER FOOTING OVER -EXCAVATION 42.0 0.0 NET HILL:I A 1-M GRADING QUANTITIES 487.66 138.52 J.C.McDonnell Engineering, PC RON HILLIARD SURFACE GRADING QUANTITIES (Manual Calculation) SECTION A 1 (FILL) SA = 544.8 SF AVERAGE DEPTH = 80.9/32PNTS = 2.52 FT FILL - 0.33' PAVEMENT = 2.22FT Al FILL VOLUME = 2.22 FT * 544.8 FT^2 = 1,209.46 CF/27= 44.8 CY SECTION A 1 (CUT) SA = 56.75 SF AVERAGE DEPTH= 6.3 / 4 = 1.58 LF Al CUT VOLUME = 1.58 FT * 56.8 FT^2 = 189.46CF/27= 3.31 CY SECTION A2 (FILL) SA = 185 SF AVERAGE DEPTH = 3.7/12PNTS = 0.308 A2 FILL VOLUME = 0.308FT * 185 FT^2 = 57.04 CF/27= 2.11 CY SECTION A2 (CUT) SA = 270 SF AVERAGE DEPTH= 38.6 /20 = 1.93 LF Al CUT VOLUME = 1.93 FT * 270 FT^2 = 521.1 CF/27= 19.3 CY SECTION A3 ASSUME 12" DUFF OVER THE AREA REPLACED W SOD SA = 376 SF A3 CUT = FILL = (1.0 FT * 376 SF) / 27 = 13.8 CY SECTION A4 (FILL) SA = 290 SF AVERAGE DEPTH = 7.9 /14PNTS = 0.56 + 0.5 ASSUMED =1.06 A4 FILL VOLUME = 1.06FT * 290 FT^2 = 307.4 CF/27= 11.38 CY SECTION A4 (CUT) SA = 290 SF A4 CUT VOLUME = 0.5 DUFF * 290 FT^2 = 145 CF/27= 5.4 CY SECTION A5 (FILL) CUT = FILL = 1-FOOT SA = 587 SF A5 FILL VOLUME = LOFT * 587 FT^2 = 587 CF/27= 21.74 CY SECTION A5 (CUT) SA = 587 SF A5 CUT VOLUME = 1.0 DUFF * 587 FT^2 = 587 CF/27= 21.74 CY SECTION A6- SWALE (FILL) SA = 0.86 SF A5 FILL VOLUME = 21.OFT * 0.86 FT^2 = 18.7 CF/27= 0.69 CY RON HILLIARD LOT GRADING (OUTSIDE FOUNDATION) FILL = 95.52 CF CUT = 63.66 CY J.C.McDonnell Engineering, PC FOUNDATION EXCAVATION CALCULATIONS (By ACAD LDD 2007 Methods) GRID Current stratum: HOUSE_DIG Site name = HOUSE_DIG Cut = 373 yards Fill = 2 yards Net = 371 yards CUT PRISM Displaying strata report for stratum: HOUSE_DIG Cut: 390 yards Fill: 84 yards Net: 307 yards (CUT) Average of two methods of Calculation = 382 Yards (CUT) GRADING TOTALS CUTS (CY) FILLS (CY) SITE GRADING (by grid area method) 63.66 95.52 FOUNDATION (by ACAD LDD) (Basement design elevation has been raised 1-foot) 382.0 43.0 ADJUSTMENT _FOR LOWER FOOTING OVER -EXCAVATION 42.0 0.0 NET HILLIARD GRADING QUANTITIES 487.66 138.52 4 J.C.McDonnell Engineering, PC J. C. Mc DONNELL & ASSOCIATES CONSULTING CIVIL ENGINEERS P.O. Box 13199 Mill Creek, WA. 98082 STORM DRAINAGE STUDY For RON HILLIARD SFR Located at 156th & 751h Place West Edmonds, WA. 98020 DEVELOPER: Mr. Ron Hilliard, PLS 20831 23rd Avenue W Lynnwood, WA. 98036-7804 Issue Date: February 1, 2007 Revision Date: July_3, 2008 PREPARED BY: J. C. McDonnell, PE Surveyor of Record: PGS Inc. 6608- 216`h Street SW Ste 304 Mountlake Terrace, WA 98043 Tel:(425) 778-5620 yr.�F 0APP VED AS NOTED ENGINEERI G ate: 15�� 8� EXECUTIVE SUMMARY The proposed project is an undeveloped lot located at the Northeast Quadrant of the intersection of 75th Place W and the unopened ROW for 156th Street SW in Edmonds, WA. 98020. The Legal Description places the property in Section 05, Township 27N, Range 03E, WM. The existing site consists of a graded building site abutting a steep embankment identified as the Meadowdale slide area. The property consists of two (2) adjacent parcels abutting the Meadowdale Beach County Park on the north. Sewer, water, telephone and power utilities are available in the street. Detention for this Single Family residence will be conventional underground concrete vault sized by the pertinent Edmonds regulation for a house of this size (3800 SF new impervious) with an internal restrictor and pipe conveyance to the public storm drain in 751h Place W. Conventional frontage improvements might be required along by the City of Edmonds but the status is unknown at this time. The existing right-of-way measures 40-feet total, twenty feet (20) from the existing ROW centerline to the subject property line. No additional dedications have been required as of this writing. Runoff from the lot will be metered into the public storm drain in 73ra Place and will be conveyed through pipes to Puget Sound to protect shoreline properties from erosion WATER QUALITY AND TESC METHODS PROPOSED Type of water quality measure(s) proposed: 1. DOE Standard erosion control BMPs will be designed at the detailed construction plan stage such as mulch, seed, hay bales, sediment traps, plastic sheeting, sediment ponds and TESC entrances to control construction runoff, as required. 2. Mulching and other winter soil management techniques will be specified in the construction plans. 2 J.C.McDonnell Engineering, PS EXISTING CONDITIONS The site is the last vacant lot at the end of 76th Place West. The site is bordered on the north with the Meadowdale County Park, to the east by a steep slope two hundred to three hundred feet high and to the south by an existing house and an unopened ROW identidfied as 1561h Street SW. The site is bordered to the west by 76th Place and a single line of houses. Beyond the houses the terrain dives sharply to the beach. In the past a building pad was fashioned at the toe of the steep slope. The site is in reasonably good and stable condition with few significant trees. The trees along the eastern edge of the building envelope the south line will probably not be impacted by the development. The Snohomish County Soil Survey lists the site soil type as Alderwood Gravely Sandy Loam with 0 to 8 percent slopes. The Gravely Sandy Loam corresponds to a type "C" soil with CN's of 81 to 85 depending upon the vegetation and cover conditions. Parcel Legal Description Section 05 Township 27 Range 04 Quarter NW LUNDS MEADOWDALE TRS BLK 000 D-01 TH PTN LOT 1 LY E OF E LN EXST CO RD TGW TH PTN VAC 73RD AVE W AS VAC UND CITY OF ED ORD NO 3201 REC UND AFN 9806030195 3 J.C.McDonnell Engineering, PS DEVELOPED SITE CONDITIONS The proposed project will construct approximately 3,790 SF of new rooftop and driveway surfaces to 0.327 acres of land. The area of the immediate building lot is 0.327 Acres. The development requires detention but perhaps not water quality treatment since the paved surfaces will be a 12-foot x 20-foot driveway and a covered garage. Total exposed driveway surface will be 440 SF. The detention is designed from Tables provided by the City of Edmonds providing standard storage volumes based upon the square footage of impervious to be constructed. The downstream storm catch basin at the corner of 76th Place W and the unopened R/W of 156th Street will be the targeted discharge point. The lot will be provided with two (2) 12" yard drains connected by 6" PVC pipe to serve the roof downspout drain system. Footing drains of the new houses shall be connected to the system downstream of the detention system, where feasible, or diverted to daylight. City requirements for frontage improvements will be developed during the preliminary SEPA process and may be added to the final working drawings later if required. To date no requirement for improvements in the 40' ROW have been indicated. Temporary erosion control BMP's will be required to control erosion and potential silt production off the construction area until the site is stabilized and the landscaping is in place. 4 J.C.McDonnell Engineering, PS SITE HYDRAULIC ANALYSIS Revised 9/22/05 The detention for the site will be conventional concrete tank, a 750 Gal septic tank, modified with a restrictor, an overflow stand pipe and an outlet orifice per Edmonds standards. The restrictor will be small diameter pipe and shall be fabricated from 4" PVC pipe and fittings. Total Property Area (2-lots) = 0.73Acres, Development Area = 0.327 Acres Existing Pervious = 0.327 Acres Existing Impervious Area = 0.000 Acres Proposed Impervious = 0.087 Acres Proposed Pervious = = 0.240 Acres Rooftop Impervious Area = 3,360 SF Access Drive Impervious = 440 SF Total Created Impervious Surface = 3,800 SF A. DESIGN CRITERIA The City of Edmonds Drainage Ordinance requires that storm water from new impervious surfaces created by development must be detained. The Drainage System Standard Plans further provides that if impervious development is less that the 5,000 sf threshold, a standard pre -tabulated City Drainage table can be used to develop the required storage volume. This site is ineligible for the Standard Plans. Specifically, the ordinance requires that "a retention control device must be provided in order to maintain surface water discharge rates at or below the 25-year, 6-hour rainfall event." It is further requires that the "retention/detention facility must be constructed to store the runoff from a 100-year, 12- hour rainfall event." The code allows the City Engineer to accept different but equivalent standards. B. DETENTION VOLUME With Impervious area = 3800 SF Detention Req'd = 95 CF (interpolated) = 710.6 Gal. Modified "750" Gal Septic Tank Inside L = 5.417' Inside W = 4.75 ` Depth = 5.08' Gal/ft = 192.46 Volume = 130.7 CF = 977.73 Gal available Air Space = 0.5' = 96.2 Gal Detention Volume = 3.78' = 727.5 Gal Dead Storage = 0.80' = 173.2 Gal Restrictor size = 1/4" per City of Edmonds 5 J.C.McDonnell Engineering, PS SITE HYDRAULIC ANALYSIS Revised 7/03/08 NOTE DUE TO THE SENSITIVE NATURE OF THE SITE , THE CITY OF` EDMONDS HAS REQUIRED THAT' ADDITIONAL STORM CALCULATIONS BE !PREPARED BASED UPON THE 25-YEAR /100-YEAR CRITERIA AS STATED'ON PAGE 5. THE FOLLOWING RESULT FLOWED FROM THE REQUIRED ADDITIONAL SBUH CALCULATION AS PROVIDED IN THE APPENDIX B. DETENTION SYSTEM LAYOUT jl. Detention Pipe_Sie 'z LEVEL POOL TABLE SUMMARY MATCH INFLOW -STO- -DIS- <-PEAK-> OUTFLOW STORAGE < ---- DESCRIPTION--> (CFS) (CFS) --ID- --ID- <-STAGE> ID (CFS) VOL (CF) 25-YEAR ....... 0.09 0.14 TANK1 R01 221.77 8 0.09 160.05 CF - - --.- .... ... -............ , Required Storage Volume = 160.05 CFw Detention Tank Volume =1,750 GAL SEPTIC TANK OR EQUAL 1,750 GAL = 58" WIDE X 100 " LONG X 74" DEEP DETENTION VOLUME OCCUPIES 4-FOOT DEPTH 48" D X 100" X 58" W = 161.1 CF > 160.05 CE 161.1 CF X 7.48 = 1,205 06 GAL LTotal Volume provided is 1,750 GAL 2 Detention Restrictor:. _N— .—.RO1MULTIPLE ORIFC_D0 ----- --�Descriptiond Outlet Elev: 2 871 Elev: 216.80 ft Orifice Diameter: 1.3096 in., The "design" #1 orifice contains a 1.31-inch (1-5/16")orifice at elevation 22 6.8, one foot below the outlet elevation. The result of this orifice design was to release-0.093 cfs, which is equal to the 25-year undeveloped runoff in the developed 100 year event fulfilling the Edmonds requirement r- - J.C.McDonnell Engineering, PS DOWNSTREAM CONDITIONS Site detention will discharge by a 6" pipe conveyance to an existing CB in the Public ROW. This CB releases to a 6" pipe to the south on 76`h Place West for 133 LF to a Public Storm Drain. The public Storm is 12" RCP to the south to the low point in 76`h and then West to Puget Sound. The 6" SD should be upgraded to a minimum 8" pipe to accommodate the Lot development drainage and the runoff from the steep slope to the east. J.C.McDonnell Engineering, PS ENGINEERING REPORT APPENDICES J.C.McDonnell Engineering, PS 1. Site Vicinity Aerial Photos J.C.McDonnell Engineering, PS 2. Aerial Topography Map 10 J.C.McDonnell Engineering, PS 3. Edmonds Drainage Calculations & Exhibit 11 J.C.McDonnell Engineering, PS 7/9/08 6:13:50 pm J.C. McDonnell & Associates page 1 RON HILLIARD SFR EDMONDS DETENTION RESIZING 2,•10, 100-yr JULY 10, 2008. BASIN SUMMARY BASIN ID: B002 NAME: 2-year undeveloped SBUH METHODOLOGY TOTAL AREA.......: 0.33 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE....: TYPElA PERV PRECIPITATION....: 1.40 inches AREA..: 0.33 Acres TIME INTERVAL....: 10.00-min CN....: 85.00 TC..... 10.99 min ABSTRACTION COEFF: '0.20 TcReach - Sheet L.: 90.00 ns:0.4000 p2yr: 2.30 s:1.0000 TcReach - Sheet L: 72.00 ns:0.4000 p2yr: 1•.30 s;0.2200 PEAK RATE: 0..02 cfs VOL: 0.01 Ac-ft TIME: 480 min IMP 0.00 Acres 0.00 0.00 min BASIN ID: BO10 NAME:'10-year undeveloped SBUH METHODOLOGY TOTAL AREA.......: 0.33 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE....': TYPEIA PERV IMP PRECIPITATION....: 2.'00 inches AREA..: , 0.33 Acres 0.00 Acres TIME INTERVAL....: 10.-00 min CN..:.: 85.00 0.00 TC..... 10.99 min 0.00 min ABSTRACTION 0.20 PEAK RATE: 0.05 cfs VOL: 0.02 AC-ft TIME: 480 min BASIN ID: 8100 NAME: 100-year undeveloped. SBUH METHODOLOGY TOTAL AREA.......: 0.33 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE....: TYPEIA PERV -IMP PRECIPITATION....: 3.10 inches AREA..: 0.33 Acres 0.00 Acres .TIME INTERVAL....: 10.00 min CN....: 85.00 0.00 TC.. .. 10.99 min 0.00 min ABSTRACTION COEFF: d.20 TcReach - Sheet L: 90.00 ns:0:2400 p2yr: 1.30 s:0.9500 TcReach - Sheet L: 72.00 ns:0.2400 p2yr: 1.30 s:0.2200 PEAK RATE: 0.11 Cfs VOL; 0.05 Ac-ft TIME: 480 min BASIN ID: D002 NAME: 2-year developed O~ SBUH METHODOLOGY © Z TOTAL AREA.......: 0.33 Acres BASEFLOWS: 0.00 cfs y Q RAINFALL TYPE....: TYPE'1A PERV IMP PRECIPITATION....: 1.40 inches AREA..: 0.24 Acres 0.09 Acre � Lu TIME INTERVAL....; 10.00 min CN....: 86.00 98'.00 O TC....: 10.00 min 10.00 min cc ABSTRACTION COEFF: 0.20 CL TcReach - Channel L: 72.00 kc:42.00 s:0.0200 'r PEAK RATE: 0.04 cfs VOL: 0.02 Ac-ft .TIME: 480 min L 9 6 3 . 00. ��j, - �t ,,�K. ON 7/9/08 6:13:50 pm J.C. McDonnell & Associates page 2 RON HILLIARD SFR EDMONDS DETENTION RESIZING 2,10, 100-yr JULY 10, 2008 BASIN SUMMARY BASIN ID: D010 NAME: 10-year developed SBUH METHODOLOGY TOTAL AREA.......: 0.33 Acres BASEFLOWS: 0.00"cfs RAINFALL TYPE....: TYPEIA PERV IMP PRECIPITATION....: 2.00 inches" AREA..: 0.24 Acres 0.09 Acres TIME INTERVAL....: 10.00 min CN..... 86.00 98.00 TC....: •10.00 min 10.00 min ABSTRACTION COEFF: 0.20 ,TcReach - ChprwrdL: 72.00 kc:42.00 S:0.0200 PEAK RAT -"j 0.07 cf8. VOL: 0.03 Ac-ft TIME: 48"0 min BASIN ID: D100* NAME: 100-year developed" SBUH METHODOLOGY TOTAL AREA.......: 0•.33 Acres BASEFLOWS.:' 0.00 cfs' RAINFALL TYPE....: TYPEIA PERV IMP PRECIPITATION....: 3.1.0 inches AREA..:. 0.24 Acres 0.09 Acres TIME INTERVAL....: 10..00 min CN."...: 86.00 98.00 TC....: 10.00 min 10.00 min ABSTRACTION COEFF: 6.20 TcReach - Cha 72.00 kc:42.00 s:0.0200 PEAK RATEr 0.14 c;s VOL: 0.06 Ac-ft TIME: 480 min A e 7/9/08 6:13:50 pm J.C. McDonnell & Associates page 3 RON HILLIARD SFR EDMONDS DETENTION RESIZING 2,10, 100-yr JULY 10, 2008 HYDROGRAPH SUMMARY PEAK TIME• VOLUME HYD RUNOFF OF OF CONTRIB NUM RATE PEAK HYDRO AREA CFS MIN. CF\ACFT ACRES UNDEVELOPED -------------------- 1 0.017 480 463 CF 0.33 2-YEAR- 2 0.046. 480 944 CF 0.33 10-YEAR 3 0.112 480 1985 CF 0.33 100-YEAR DEVELOPED 4 0.038 480 745 CF 0.33 2-YEAR 5' 0.072 480. 1300•CF 0.33 10-YEAR 6 0.142 480 2429 CF 0.33 100-YEAR TANK PERFORMANCE 7 0.012 680 745 CF 0.33 2-YEAR .8 0 .047 510 1300 CF 00AR 9 0.115 500 2429 CF 0.33 '100-YEAR,' 7/9/08 6:13:50 pm J.C. McDonnell & Associates page 4 RON HILLIARD SFR EDMONDS DETENTION RESIZING.2, 10, 100-yr JULY 10, 2008 STAGE STORAGE TABLE RECTANGULAR VAULT ID No. Tankl Description: 1750 GAL.SEPTIC TANK Length: 8.33 ft. width: 4.83 ft. voids: 1.000 STAGE <-STORAGE--> STAGE <---- STORAGE ---- > STAGE <----STORAGE----> STAGE <---- STORAGE ---- > (FT)---CF--- --AC-FT- (FT)---CF-----AC-FT- (FT) ---CF--- --AC-FT- (FT) --- CF ------ AC -FT,- 217.80 0.0000 0.0000 219.40 64.437 0.0015 221.00 128.87 0.0030 222.60 193.31 0.0044 -217.90 4.6273 0.0001 219.50 68.465 0.0016 221.10 132.90 0.0031 222:70 197.34 0.0045 218.00 8.0547 0.0002 219.60 72.492 0.0017 221.20 136.93 0.0031 222.80 201.37 0.0046 218.10 12.082 0.0003 219.70 76.519 0.0018 221.30 140.96 0.0032 222.90 205.39 0.0047 218.20 16.109 0.0004 219.80 80.547 •.0.0018 . 221.40 144.98 0.0033 223.00 209.42 0.0048 218.30 20.137 0.0005 219.90 84,574 0.0019 221.50 149.01 0.0034 223.10 213.45 0.0049 218.40 24.164 0.0006 220.00 88.601 0.0020 221.60 153.04 0.0035 223.20 217.48 0.0050 218.50 28.191 0.0006 220.10 92.629 0,0021 221.70 157.07 0.0036 223.30 221.50 0.0051 218.60 32.219 0.0007 220.20 96.656 0.0022 221.80 161.09 0.0037 223.40 225.53 0.0052 218.70 36.246.0.0008 220.30 100.68 0.0023 221.90 165.12 0.0038 223.50 229.56 0.0053 218.80 40.273 0.0009. 220.40 104.71 0.0024 222.00 169.15 0.0039 223.60 233.59 0.0054 218.90 44.301 0.0010 220.50 108.74 0.0025 222.10 173.18 0.0040 223.70 .237.61 0.0055 219.00 48.328 0.0011 220.60 112.77 0.0026 222.20 177.20 0.0041 223.86 241.64 0.0055 219.I0. 52.355 0,0012. 220.70 116.79 0.0027 222.30 181.23 0.6042 223.90 245.67 0.0056 219.20 56.383 0.0013 220.80 120.82.0.0028 222.40 185.26 0.0043 224.00 249.70 0.0057 219.30 60.410 0.0014 220.90 124.85 0.0029 222.50 189.28 0.0043 L/ C� 7/9/08 6:13:50 pm J.C. McDonnell & Associates page 5 RON HILLIARD SFR EDMONDS DETENTION RESIZING 2, 10, 100-yr JULY 10, 2008 STAGE DISCHARGE TABLE MULTIPLE ORIFICE ID No. R01'. Description: Outlet Elev: 217.80. Ct Elev: 215.80 ft orifice Diame6<DISCHARGE> Elev: 221.10 ft Orifice 2 Diame Elev: 222.20 ft Orifice 3 Diame STAGE: <--DISCHARGE-> STAGE <DISCHARGE> STAGE E <--DISCHARGE --- > (FT) CPS-- ^- (FT) --- CFS--.------- (FT) --- cps --------- (FT)---cFS-- 217.80 0.0000 218.90 0.0073 220.00 0.0103 221.10 0.0127 217,90 0.0022, 219.00 •0.0076 220.10 0.0106 221.20 0.0236 218.00 0.0031 219.10 6.0079 220.20 0.0108 221.30 0.0283 218.10 0.0038 219.20 0.0082 220.30 0.0110 221.40 0.0319 218.20 0.0044 219.30 0.0085 • 220.40 0.0112 221.50 0.0349 218.30 0,0049.. ' 219.40. 0.0088 220.50 0.0115 221.60 0.0377. 218.40 0.0054 219.50 0.0091 220.60 0.0117 2200 0.0401 218.50 0.0058 219.60 0.0094 220.70 0.0119 221.80 ' 0.0424, 218.60 0.0062 219.70 0.0096: 220.80 0.0121 221.90 0.0446 218.70 0.0066 219.80 0.0099 ' 220.90 0.0123 222.00 0.0466 218.80 .0.0070 219.90 0.0101 221.00 0.0125 7/9/08 6:13:50 pm J.C. McDonnell & Associates page 6 RON HILLIARD SFR EDMONDS DETENTION RESIZING 2,10, 100-yr JULY 10, 2008 ----------- STAGE DISCHARGE TABLE' RISER DISCHARGE ID No. R02 Description: Riser Diameter (in): 6.00 elev: 223.80 ft Weir Coefficient...: 9.739 height: 224.80 ft Orif Coefficient...: 3.782 increm: 0.10 ft STAGE <DISCHARGE> STAGE <DISCHARGE> STAGE. <--DISCHARGE---> STAGE <--DISCHARGE---> (FT) ---CFS-- - (FT) ---CFS--=--�--- (FT) ---CFS-- (FT) ---CFS=-------- 223.80 0.0000 224.00 0.4228 224.30 0.6686 224.60 0.8457 223.80 0.0000 224.10 0.5179 224.40 0.7324 224.70 0.8970 223.90 0.2990 224.20 0.5980 224.50 0.7911 224.80 0.9455 S 7/9/08 6:13:50 pm J.C. McDonnell & Associates page 7 RON HILLIARD SFR EDMONDS DETENTION RESIZING 2, 10, 100-yr JULY 10, 2006 STAGE DISCHARGE TABLE COMBINATION DISCHARGE ID NO. R03 Description: Structure: R01 Structure: Structure: R02 Structure: Structure: STAGE <--DISCHARGE --- > STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> STAGE <--DISCHARGE-> (FT) ---CFS-- ------- (FT)' ---CFS-- -------• (FT) --- CFS-- ------ - (FT) -'--CFS-- ------- 217.80 0.0000 219.40 0.0088 221.00 0.0125 222.60 0.0785 217.90. 0.0022 . 219.50 0.0091 221.10 0.0127 222.70 0.0826 218.00 0.0031 219.60 0.0094 221.20 0.0236 222.80 0.0863 218.10 0.0038 219.70 .0.0096 221.30 0.0283 222.90 0.0899 218.20 0.0044 219.80 0.0099 221.40 0.0319 223.00 0.0933 218.30 0.0049 219.90 '0.6101 221.50 0.0349 223.10 0.0965 218.40 0.0054 220.00 0.0103 221.60 0.0377 223.20 0.0996 218.50 0.0058 220.10 0.0106 221.70 .0.0401 223.30 0.1025 218.60 0.0062 220.20 0.0108 221.80 0.0424 223.40 - 0.1054 218.70 0..0066 220.30 0.0110 - 221.90 0.0446 223.50 0.1082 218.80 0.0070 220.40' 0.0112 222.00 0.0466 223.60 0.1109 218.90 0.0073 220.50 0.0115 222.10 0.0485. 223.10 0.1135 219.00 0.0076 220.60 0.0117 222.20 0.0503 223.80 0.1161 219.10 0.0079 220.70 0.0119 222.30 6.0628 223.90 0.4176 219.20 0.0082 . 220.80 0.6121 222.40 0.0690 .224.00 0.5438 ..219.30 0.0085 220.90 0.0123 222.56 0.0740 7/9/08 6:13:51.pm J.C. McDonnell & Associates page 8 RON HILLIARD SFR EDMONDS DETENTION RESIZING 2,10, 100-yr JULY 10, 2008 LEVEL POOL TABLE SUMMARY MATCH INFLOW -STO- -DIS- <-PEAK-> OUTFLOW STORAGE < " -DESCRIPTION---> (CFS) (CFS) --ID- --ID- <=STAGE> ID (CPS) VOL (CF) 2-1YEAR ....................... 0.01 0.04 TANKI R03 221.01 7 0.01 129.41 CF 10-YEAR ...................... 0.05 0.07 TANK], R03 222.04 8 0.05 170.81 CF 100-YEAR ...................... 0.11 0.14 TANK1 R03 223.7.5 9 0.11 239.74 CF .7o, J. C. Mc DONNELL & ASSOCIATES CONSULTING CIVIL ENGINEERS P.O. Box 13199 Mill Creek, WA. 98082 GRADING QUANTITIES REPORT For RON HILLIARD SFR Located at 156th & 75" Place West Edmonds, WA. 98020 DEVELOPER: Mr. Ron Hilliard, PLS 2083123rd Avenue W Lynnwood, WA. 98036-7804 Issue Date: April 21, 2008 PREPARED BY: J. C. McDonnell, PE Surveyor of Record: PGS Inc. 6608- 216`h Street SW Ste 304 Mountlake Terrace, WA 98043 Tel:(425) 778-5620 ESUB APR 2 4 2008 BUILDING DEPARTMENT CITY OF EDMONDS STREET FILE RON HILLIARD SURFACE GRADING QUANTITIES (Manual Calculation) SECTION Al (FILL) SA = 544.8 SF AVERAGE DEPTH = 80.9/32PNTS = 2.52 FT FILL - 0.33' PAVEMENT = 2.22FT Al FILL VOLUME = 2.22 FT * 544.8 FT^2 = 1,209.46 CF/27= 44.8 CY SECTION Al (CUT) SA = 56.75 SF AVERAGE DEPTH= 6.3 / 4 = 1.58 LF Al CUT VOLUME = 1.58 FT * 56.8 FT^2 = I89.46CF/27= 3.31 CY SECTION A2 (FILL) SA = 185 SF AVERAGE DEPTH = 2.44/12PNTS = 0.20 A2 FILL VOLUME = 0.20FT * 185 FT^2 = 37.61 CF/27=1.39 CY SECTION A2 (CUT) SA = 270 SF AVERAGE DEPTH= 34.5 /20 = 1.73 LF Al CUT VOLUME = 1.73 FT * 270 FT^2 = 465.6CF/27=17.24 CY SECTION A3 ASSUME 12" DUFF OVER THE AREA REPLACED W SOD SA = 376 SF A3 CUT = FILL = (1.0 FT * 376 SF) / 27 = 13.8 CY SECTION A4 (FILL) SA = 290 SF AVERAGE DEPTH = 7.9 /14PNTS = 0.56 + 0.5 ASSUMED =1.06 A4 FILL VOLUME= 1.06FT * 290 FT112 = 307.4 CF/27= 11.38 CY SECTION A4 (CUT) SA = 290 SF A4 CUT VOLUME = 0.5 DUFF * 290 FT^2 = 145 CF/27= 5.4 CY SECTION A5 (FILL) CUT = FILL = 1-FOOT SA = 587 SF A5 FILL VOLUME = LOFT * 587 FT^2 = 587 CF/27= 21.74 CY . SECTION A5 (CUT) SA = 587 SF A5 CUT VOLUME = 1.0 DUFF * 587 FT^2 = 587 CF/27= 21.74 CY SECTION A6- SWALE (FILL) SA = 0.86 SF A5 FILL VOLUME = 21.OFT * 0.86 FT^2 = 18.7 CF/27= 0.69 CY RON HILLIARD LOT GRADING (EXTRA FOUNDATION FILL = 93.80 CF CUT = 61.5 CY 2 J.C.McDonnell Engineering, PS Foundation Excavation Calculations GRID Current stratum: HOUSE —DIG Site name = HOUSE DIG Cut = 417 yards Fill = 2 yards Net = 415 yards CUT PRISM Displaying strata report for stratum: HOUSE —DIG Cut: 435 yards Fill: 84 yards Net: 351 yards (CUT) Average of two methods of Calculation = 426 Yards (CUT) .i 4 d ) 7 .` e { `F Silty Sand, Clayey Sand - Internal Angle of Friction (4)) = 28' Non Reinforced Walls with 41" Wide Blocks Load Condition A, B, and C Place planter blocks to approximate average batter angle. The above chart was prepared by Redi-Rock- International for estimating and conceptual design purposes only. All information Is believed to be We and accurate, however, Redi-RockT International assumes no responsibility for the use of these design charts for actual construction. Determination of the suitability of each chart is the sole responsibility of the user. Final designs for construction purposes must be performed by a registered Professional Engineer, using the actual conditions of the proposed site. Other Notes: RE SUB 1. Unit weight of 28', 30°, 34' and 40' soils is assumed to be 120pcf. 5. The wall design shall address both internal and external 2. Minimum factors of safety are 1.5 for sliding, 1.5 for overturning drainage and shall be evaluated by the Professional Engineer J U N 2 4 2008 and 2.0 for bearing capacity. who Is responsible for the final wall design. 3. Designs are in general accordance with NCMA's Design Manual 6. Backfill material to be compacted to 95% standard proctor. BUILDING DEPARTMENT for Segmental Retaining Walls (2nd ed.). 7. All Redi-Rock"I International Wall System Specifications are CITY OF EDMONDS 4. Global stability has not been addressed in these charts. to be followed. Redi-Rock® International, LLC ©All Rights Reserved 6 Design Resources January 2007 Edition SPECIFICATIONS FOR REDI-ROCK041" SERIES WALL SYSTEM PART]: GENERAL 1.1 Scope Work includes furnishing and installing concrete retaining wall units to the lines and grades designated on the construction drawings and as specified herein. 1.2 Reference Standards ASTM C94 Ready -Mixed Concrete ASTM C1372 Segmental Retaining Wall Units 1.3 Delivery, Storage, and Handling A. Contractor shall check the materials upon delivery to assure proper material has been received. B. Contractor shall prevent excessive mud, wet cement and like materials from coming in contact with the SRW units. C. Contractor shall protect the materials from damage. Damaged material shall not be incorporated in the project. PART 2: MATERIALS 2.1 Wall Units A. Wall units shall be Redi-Rock® as produced by a licensed manufacturer. B. Wall units shall be made with Ready -Mixed concrete in accordance with ASTM C94, latest revision. and ner the following chart- 28 Day Compressive Climate Air Content Strength, psi Slump* Negligible 1'/2%-4%2% 4000 5" t1 %2" Moderate 30/o-6% 4000 5" fl %2" Severe 4%2%-7%2% 4000 5" tl ''/2" *Higher slumps are allowed if achieved by use of appropriate admixtures. Notwithstanding anything stated above, all material used in the wall units must meet applicable ASTM and local requirements for exterior concrete. [Innate Zonis C. Exterior block dimensions shall be uniform and consistent. Maximum dimensional deviations shall be 1 % excluding the architectural surface. Maximum width (face to back) deviation including the architectural surface shall be 1.0 inch. D. Exposed face shall be finished as specified. Other surfaces to be smooth form type. Dime -size bug holes on the block face may be patched and/or shake -on color stain can be used to blend into the remainder of the block face. 2.2 Leveling Pad and Free Draining Backfill A. Leveling pad shall be crushed stone. See detail sheet defining Leveling Pad options for drain placement in the bottom of the foundation leveling pad. B. Free Draining Backfill material shall be washed stone and shall be placed to a minimum of 1' width behind the back of the wall and shall extend vertically from the Leveling Pad to an elevation 4" below the top of wall. C. Backfill material shall be approved by the geotechnical engineer. Site excavated soils may be used if approved unless otherwise specified in the drawings. Unsuitable soils with a PL>6, organic soils and frost susceptible soils shall not be used within a 1 to 1 influence area. Red! -Rock® International, LLC 0 All Rights Reserved FEB. 2008 UPDATE 9 Design Resources January 2007 Edition T 7A,1.•y ys '1C^t 1 t3s, r � n •; SPECIFICATIONS FOR REDI-ROCK041" SERIES WALL SYSTEM D. Non -woven geotextile cloth shall be placed between the Free Draining Backfill and retained 3.4 soil if required. E. Where additional fill is needed, Contractor shall submit sample and specifications to the Engineer for approval. 2.3 Drainage A. Internal and external drainage shall be evaluated by the Professional Engineer who is responsible for the final wail design. 2.4 Geogrid Connection A. Fiberglass rod used in the Type IAT Geo-Grid connection shall be 7/16" diameter. Only fiberglass rod obtained from an authorized Redi- Rock® dealer shall be used. PART 3: CONSTRUCTION OF WALL SYSTEM 3.1 Excavation A. Contractor shall excavate to the lines and grades shown on the construction drawings. 3.2 Foundation Soil Preparation A. Native foundation soil shall be compacted to 95% of standard proctor or 90% of modified proctor prior to placement of the Leveling Pad material. B. In -situ foundation soil shall be examined by the Engineer to ensure that the actual foundation soil strength meets or exceeds assumed design strength. Soil not meeting the required strength shall be removed and replaced with acceptable, compacted material. 3.3 Leveling Pad Placement A. Leveling Pad shall be placed as shown on the construction drawings. B. Leveling Pad shall be placed on undisturbed native soils or suitable replacements fills. C. Leveling Pad shall be compacted to 95% of standard proctor or 90% of modified proctor to ensure a level, hard surface on which to place the first course blocks. Pad shall be constructed to the proper elevation to ensure the final elevation shown on the plans. D. Leveling Pad shall have a 6 inch minimum depth for walls under 8 feet in height and a 12 inch minimum depth for walls over 8 feet. Pad dimensions shall extend beyond the blocks in all directions to a distance at least equal to the depth of the pad or as designed by Engineer. E. For steps and pavers, a minimum of 1" - 1 %:" of free draining sand shall be screeded smooth to act as a placement bed for the steps or pavers. Redi-Rock® International, LLC ©All Rights Reserved 10 Unit Installation A. The first course of wall units shall be placed on the prepared Leveling Pad with the aesthetic surface facing out and the front edges tight together. All units shall be checked for level and alignment as they are placed. B. Ensure that units are in full contact with Leveling Pad. Proper care shall be taken to develop straight lines and smooth curves on base course as per wall layout. C. The backfill in front and back of entire base row shall be placed and compacted to firmly lock them in place. Check all units again for level and alignment. All excess material shall be swept from top of units. D. Install next course of wall units on top of base row. Position blocks to be offset from seams of blocks below. Blocks shall be placed fully forward so knob and groove are engaged. Check each block for proper alignment and level. Backfill to 12 inch width behind block with Free Draining Backfill. Spread backfill in uniform lifts not exceeding 9 inches. Employ methods using lightweight compaction equipment that will not disrupt the stability or batter of the wall. Hand - operated plate compaction equipment shall be used around the block and within 3 feet of the wall to achieve consolidation. Compact backfill to 95% of standard proctor (ASTM D 698, AASHTO T- 99) density within 2% of its optimum moisture content. E. Install each subsequent course in like manner. Repeat procedure to the extent of wall height. F. Allowable construction tolerance at the wall face is 2 degrees vertically and 1 inch in 10 feet horizontally. G. All walls shall be installed in accordance with local building codes and requirements. 3.5 Geogrid Installation A. See Wall Installation instructions. PART 4: AVAILABILITY Redi-Rock® International 05481 South US-31, Charlevoix, MI 49720 1-866-222-8400 www.redi-rock.com info@redi-rock.com FEB. 2008 UPDATE Design Resources January 2007 Edition REDNROCK Typical Gravity Wall with 41" Blocks No Scale SETBACK = 1.25"' (4.0° Batter Angle on Wall) Note: Load Condition A Shown 28" Top Block (No Bac(slope - No Surcharge) Ground Level �,�; T 1-1'I Illhlil_�'L—Iil-11r ll!-�= I III II T, iz±I I II.I !:I I III _I _.:II .III III. TIT - r, Move Blocks Forward During In stalltion to Engage Shear ! fl .: _5.,. •.: , :..,.: I (Typical) T YPcal i ��•• - 11 !!- ) � Exposed -1 Wall Wall �FI" 41" Middle Block Height=i!1= Ground Level 77 II.. $inept II Ili,-ill- _Ju Leveling Fad: I_ I! I III I —III=1 —11 Free Draining Backfill to Extend a- -I at Least 12" Behind Wall Non -Woven Geotextile Fabric (If Specified) ,r, I n_ ;i !i 41" Bottom Block ! — I-- i:=i; Crushed Stone Leveling Pad See Redi-Rock.com for Detailed Section Drawings of Each Condition Shown in the Design Charts Perforated Sock Drain (As Specified by Engineer) Redi-Rock® International, LLC © All Rights Reserved 11 Design Resources January 2007 Edition 41" Series Blocks Top - 28" Volume = 8.55 cft Weight = ±1223 Ibs C of G = 15.06" 46-1/8"-,,,""",, 28" 10" Dia. 4" High (TYp•) Middle - 41" Volume = 16.44 cft Weight = ±2351 Ibs C of G = 20.92" 46-1/8"� 10" Dia. 4" High (TYPJ Bottom - 41" Volume = 17.37 cft Weight = ±2483 Ibs CofG=21.3" 46-1/8"� Planter Volume =14.12 c Weight = ±2020 II C of G = 19.35" \36" NOTES: Volume and Center of Gravity (C of G) calculations are based on the blocks as shown. Center of Gravity is measured from the back of the block. Half blocks include a fork lift slot on one side. Actual weights and volumes will may vary. Weight shown is based on 143 pof concrete. 5" 13" 18" B" Half Top - 28" Volume = 4.13 cft Weight = ±591 Ibs �. _ a ss trS'i j� 5" 13" 13" Half Middle - 41" Volume = 7.28 cft 18" Weight = ±1041 Ibs 41" 23-1/16" 13" Half Bottom - 41" Volume = 7.73 cft 18" Weight = ±1105 Ibs a1" 23-1116 13" Half Planter 1s" Volume = 5.91 cft 18" Weight = ±890 Ibs 8"" 41" 23-1/16" FEB. 2008 UPDATE Redi-Rock® International, LLC 0 All Rights Reserved 12 Design Resources January 2007 Edition Steps Used with 41" Series Blocks 3-Sided Straight Step Volume = 4.58 cft Weight = ±655 Ibs 7" 46" 26' 4-Sided 6" Cap Block Volume = 4.81 cft Weight = ±688 Ibs Corner Block Finished on Three Sides Perimeter Free -Standing Series Used with 41" Series Blocks 7 z" Garden Corner Volume = 8.26 cft Weight = t1182 Ibs 46- Top Corner (available with textured top) Volume = 10.44 cft Weight = ±1493 Ibs 46-1/8" Middle Corner Volume = 10.51 cft Weight = t1502 Ibs (Bottom Corner Block does not have groove) 46 NOTES: Cobblestone face is 24" wide and limestone face is approximately 23" wide. Volume calculations are based on the blocks as shown. Actual weights and volumes will may vary. Weight shown is based on 143 pcf concrete. Half Garden Corner Volume = 4.25 cft Weight = ±607 Ibs 18" 18" 24" 23-1 /16, j 18" Half Top Corner (available with textured top) Volume = 5.19 cft Weight = t742 Ibs 16^ 23-1/16" 24" Half Middle Corner Volume = 5.28 cft Weight = ±755 Ibs 18" (Half Bottom Comer Block does not have YP124" groove) 23-1/16" 6.a1 i "/' I Redi-Rock'International, LLC I 1 I I Steos and Comers for 41in Series.dwo I — 1 NO SCALE FEB. 2008 UPDATE Redi-Rock® International, LLC ©All Rights Reserved 13 Design Resources January 2007 Edition e...''B'D R-,OCK E -1� Specialty Blocks Used with 41" Series Blocks Protruding Plan Volume =15.45 cft Weight = ±2210 Ibs CofG=24.71" Note: Limestone face shown. Cobblestone face also available. Drain Ditch Block Volume = 11.28 cft Weight = ±1614 Ibs C of G = 21.57" Anchor Block Volume = 15.80 cft Weight = ±2259 Ibs C of G = 21.2" 46-1/8" \ / \e- 46-1/8" NOTES: Volume and Center of Gravity (C of G) calculations are based on the blocks as shown. Center of Gravity is measured from the back of the block. Half blocks include a fork lift slot on one side. Actual weights and volumes will may vary. Weight shown is based on 143 pof concrete. 23" End Block Volume = 6.79 cft �18" Weight = t 970 Ibs CofG=12.29" �18" 38" 23" Note: This block can also be used with the 28" Series blocks. Half Drain Ditch Block 1 13" —� Volume = 5.01 cft 16" Weight = t717 Ibs 18" C of G = 22.96" 31" 41" 23-1/16" 41" FEB. 2008 UPDATE Redi-Rock® International, LLC © All Rights Reserved 14 ) Design Resources January 2007 Edition TFttt L i` <a Typical Block Setbacks SETBACK = 1.25" -1 F 10 00 2 1.00(4.0" Batter Angle on Wall) .... ..:. 4.00 x elk' 18.00 4.50 : I I. -- I 11.00 F- — 22.26 41.00 Al" Patnininn RInr4 01 Move Blocks Forward During Installation to Engage Shear Knobs (Typical) , no 4.50 11.00 22.25 . 41.00 t Planter Block Zero -Setback -Mill Usinq 7 1/2 Shear°Knob J. JOHNSON 11/02/07 atEa�aev Redi-Rock International, LLC 1 I I Typical Block Setbacks for 41in Sedes.dwo I ___ 1 1 OF 1 Redi-Rock® International, LLC ©All Rights Reserved 15 Design Resources January 2007 Edition REDI�ROCK 41 41" Middle Block with Soil Infill Concrete (143pcf) Volume (Vc) —> 16.44 cf (from block specifications charts) Center of Gravity (COGc) —> 20.92 in (from block specification charts) Total Weight (Pc) —> 2351 Ibs Pc = (16.44 ft^3)(143 Ibs/ft^3) = 2351 Ibs Soil (100pcf) Volume (Vs) —> 1.88 cf Vs = [0.5(5 in)(36 in)(18 in)] x [(1 ft^3) / (1728 inA3)] x 2 sides = 1.88 cf Center of Gravity (COGs) —> 12.00 in COGs = (36 in)(1/3) = 12.00 in Total Weight (Ps) —> 188 Ibs Ps = (1.88 ft^3)(100 Ibs/ft^3) = 188 Ibs Force Calculations EFx=0 EFy=P-Pc-Ps=0 P = (2351 Ibs) + (188 Ibs) = 2539 Ibs P = 2539 Ibs EMa = Pc(COGc) + Ps(COGs) - P(COG) = 0 COG = [(2351 Ibs)(20.92 in) + (188 Ibs)(12.00 in)] / [2539 Ibs] = COG COG = [(49182.92 Ibin) + (2256 Ibin)] / [2539 Ibs] = 20.26 in SRWall COG = (40.76 in) - (20.26 in) = 20.49 In For wall calculations, center of gravity = 20.49 inches from the front face 3. i F r w - 1c Redi-Rock® International, LLC O All Rights Reserved 16 FEB. 2008 UPDATE 9 Design Resources January 2007 Edition i 9 Cornerstone :;:.: Geotechnical, Inc. January 22, 2007 Mr. Ron Hilliard 6608 — 216'h Street SW, Suite 304 Mountlake Terrace, Washington 98043 Geotechnical Engineering Report Proposed Single Family Residence 156`h Street Southwest and 75' Place West Parcel No. 00500900000101 Edmonds, Washington CG File No. 2212 I I I Dear Mr. Hilliard: INTRODUCTION 17625-13V Ave. NE, C102, Woodinville, WA 98072 Phone: 425-844.1977 Fax: 425-844.1987 This report presents the results of our geotechnical engineering investigation for the proposed residential project in Edmonds, Washington. The site is located within the Meadowdale slide area, northeast of the intersection of 75'h Place West and the easement for 156'h Street Southwest, as shown on the Vicinity Map in Figure 1. The Meadowdale slide area is located approximately between 165" Street Southwest and Meadowdale Beach County Park in the north -south direction, and Puget Sound and 68'h Avenue West in the east -west direction. This feature is approximately 3,000 feet long and 500 to 800 feet wide. At .your request, we have completed this report to evaluate the subsurface conditions at the property and provide recommendations for site development and risks associated with development within a landslide area. We have received a site plan showing the slope area and planned house layout, as well as the City of Edmonds' Earth Subsidence Landslide Hazard Area (ESLHA) packet. The ESLHA packet includes information, requirements, and regulations concerning construction within the Meadowdale landslide area in the City of Edmonds. PROJECT DESCRIPTION The property includes a steep slope area with magnitudes greater than 100 percent, as well as a nearly level portion that slopes down toward 75`h Place West. The current development plan indicates that a I Geotechnical Engineering Report Proposed Single Family Residence Edmonds, Washington January 22, 2007 CG File No. 3212 Page'2 two-story wood -framed structure with a partial daylight basement will be constructed. A driveway will extend from 75`h Place West onto the property west of the proposed residence. Portions of the basement level will not be fully excavated, leaving areas with crawlspace in the northeast portion of the residence._ We expect cuts of 6 to 8. feet for portions of the basement level. The northeast corner of the structure will extend into the steep slope. We have discussed the potential of debris flows from the steep slope area. The structure will need to be designed for this loading condition, or a separate debris wall will have to be constructed. We understand that the northeast . comer of the residence will be designed to accommodate the loads, but as the structure is located away from the slope to the south, a debris wall will need to be constructed. SCOPE The purpose of this study is to explore and characterize the subsurface conditions and present recommendations for site development. Specifically, our scope of services as outlined in our Services Agreement, dated July 11, 2005, includes the following: 1. Review of soils and geologic maps of the area,. including the ordinances specific to the Meadowdale area 2. Evaluate subsurface soil and ground water conditions at the site with a subcontracted backhoe. 3. Provide an evaluation of the steep slope portion of the Site and recommendations for mitigating the risk posed to the proposed residence by this slope. 4. Provide recommendations for building foundations. 5. Provide recommendations for site preparation and grading 6. Provide general surface drainage recommendations. 7. Meet with .you and your designer to discuss site constraints on the project. 8. Prepare a written report to document our findings and recommendations. Cornerstone Geotechnical, Inc. � f Geotechnical Engineering Report Proposed Single family Residence Edmonds, Washington January 22, 2007 CG File No. 2212 Page 3 SITE CONDITIONS Surface Conditions The site consists of one parcel with an area of approximately 0.38 acres, with a north -south length of approximately 100 feet and an east -west length of approximately 165 feet. The property is bordered to the west by 7P Place West, to the east and south by residential structures, and to the north by an undeveloped lot. A'layout of the site is shown on the Site Plan in Figure 2. The topographic map indicates that the eastern three-quarters of the site slopes downward to the west and southwest at inclinations of 100 to 115 percent, with a site elevation change of approximately 75 to 85 feet. We estimate that the slope continues off -site another 20 feet. This slope area is vegetated with blackberry, grasses, and vine maple, as well as sparse maple, alder, and fir trees. The largest trees have been located by surveying, and are shown on the Site Plan. A debris slide occurred within the last 20 years just south of the site, along the easement for 1566' Street Southwest. At this time, this area is vegetated with brush and a new above -ground storm line is in place extending down the slope. The area of the proposed structure slopes gently downward to the west and southwest at inclinations of 10 to 15 percent; with an overall elevation change of about 6 feet, and is vegetated with blackberry and grasses. The western margin of the site slopes down to 75'h Place West at an inclination of approximately 75 percent, with an overall elevation change of 10 feet. That slope is vegetated with brush and grasses: Geology Most of the Puget•Sound region was affected by past intrusion of continental glaciation. The last period of glaciation, the Vashon Stade of the Fraser Glaciation, ended approximately 11,000 years ago. Prior to the Fraser Glaciation, non -glacial sediments, including interbedded mixtures and layers of sand, silt, clay, and gravel were deposited and together with older glacial deposits, were subsequently eroded by the most recent glaciation. The Preliminary Surficial Geologic Man of the Edmonds East and Edmonds West Quadrangles, by Mackey Smith, dated 1975, was reviewed for this site. The site is shown to be located in an area where pre-Vashon geologic units of the Whidbey and Double Bluff Formations exist. Vashon Advance outwash and glacial till are mapped at higher elevations. Specifically; this site is mapped as being within a large landslide feature. Cornerstone Geotechnical, Inc. Geotechnical Engineering Report Proposed Single Family Residence Edmonds, Washington January 22, 2007 CG File No. 2212 Page 4 The landslide has been the subject of previous geotechnical studies by Roger Lowe and Associates and GeoEngineers, Inc. These studies provided evaluations of the slide and recommendations to increase the stability of the slide mass.. The most significant recommendations for increasing the stability was the installation of drains within and adjacent to the slide mass. The Roger Lowe report included a map of the landslide where specific hazards were mapped, with an estimate of the probability of reoccurrence. The GeoEngincers report modified that map to reflect decreased reoccurrence probabilities based on the drainage improvements. We understand that these probabilities were derived from a qualitative assessment based on historical movements. They were not based on rigorous probability analysis. Our subsurface explorations encountered stiff to hard silt within the steep slope areas, consistent with pre- Vashon sediments, and a loose to medium dense mixture of sand, silt, and gravel in the western quarter of the site, consistent with colluvium or. landslide debris derived from the outwash and till deposits, found upslope of the site. Explorations Subsurface conditions were explored at the site on October 25, 2006, by excavating four test pits with a subcontracted backhoe. The test pits ranged in depth from 13.0 to 15.5 feet below the ground surface. The explorations were located and logged in the field by a geologist from this firm who also examined the soils and geologic conditions encountered. The site and test pit conditions were also observed by Dr. Donald W. Tubbs, LEG, a sub -consultant engineering geologist we have retained for this project. The. approximate locations of the test pits are shown on the Site Plan in Figure 2. Cross -sections, showing the subsurface soils and topography in profile, are presented in Figures 3 and 4. The soils were visually classified in general accordance with the Unified Soil Classification System, a copy of which is presented as Figure 5, The logs of the test pits. are presented in Figures 6 and 7. Subsurface Conditions A brief description of the conditions encountered in our explorations is included below: A more detailed description of the soils encountered can be found in the test pit logs in Figures 6 and 7. Test Pit 1 encountered loose to medium dense, silty fine to medium grained sand with variable amounts of gravel and organic debris, indicative of landslide debris, down to the termination depth of Test Pit 1. Test Pits 2 and 3 encountered 3.0 to 5.0 feet of loose to medium dense fill, consisting of silty fine sand Cornerstone Geotechnical, Inc. Geotechnical Engineering Report Proposed Single Family Residence. Edmonds, Washington January 22, 2007 CG File No. 2212 Page 5 with variable amounts of gravel, underlain bya l A to 1.5 foot -thick layer of buried topsoil. The topsoil layer is loose to medium dense and includes wood debris up to 18 inches in diameter. Below the topsoil is a medium dense/stiff mixture of sandy silt and silty fine sand with variable amounts of gravel, indicative of landslide debris, down to the termination depth of Test Pits 2 and 3. Test Pit 4 was located - about 8 feet north of Test Pit 1, in the face of the steep slope, and encountered 8,5"feet of stiff to hard silt, consistent with pre-Vashon sediments. An apparent shear zone with a dip of approximately 60 degrees, and a thickness of 18 inches was observed in the test pit, southwest of the hard silt. As the test pit was advanced downward and to the southwest, a variable mixture of silt and silty fine sand with variable amounts of gravel and organic debris was encountered, consistent with landslide deposits; down to the Itermination depth of Test Pit 4. Hydrologic Conditions Groundwater seepage was not observed in the excavated test pits. If groundwater is encountered during construction, it would most likely be found in pockets, perched on less permeable .strata within the landslide debris. Perched water does not represent a regional ground water "table" within the upper soil horizons. Volumes of perched ground water vary depending upon the time of, year and the upslope recharge conditions. GEOLOGIC HAZARDS General Meadowdale Landslide Description The Meadowdale landslide complex consists of historic block movements, slumps, and debris slides. This is a large-scale feature; approximately 3,000 feet long and 500 to 800 feet wide. The system includes large rotational slides extending through the underlying silt, with lateral movements within smaller landslide blocks. The blocks are composed of glacial till, outwash, and pre-Vashon silts, and the debris slides are comprised of colluvium. Groundwater collection and diversion systems were installed in the early 1980's, and have helped reduce the likelihood of landslide activity. The Roger Lowe and Associates report discussed the probability of slope movement for a given location in thecomplex based on the observed topographic and geologic conditions. The follow-up report by GeoEngineers and accompanying map include the previous reports' description and probabilities, along with updated probabilities based on the affect the drainage systems had on the overall groundwater levels Cornerstone Geotechnical, Inc. Geotechnical Engineering Report Proposed Single Family Residence Edmonds, Washington January 22, 2007 CG File No. 2212 Page 6 in the area. This map indicates that the site is located within an area with `hazards from encroaching landslide materials' and `hazards from ground failure in previously failed material.' The first hazard is from material sloughing off the steep slope in the eastern portion of the property. The second hazard would be from movement of the large blocks within the slide complex, below the steep slope. General Site Landslide Description The site includes two distinct types of landslide -derived topographic regions. The eastern portion of the property consists of an over -steepened slope area that we interpret to be a slide scarp. This slope is generally comprised of pre-Vashon sediments, and covered with 1 to 2 feet of colluvium and vegetation. The western portion of the property is nearly level, and consists of a relatively intact and uniform block of landslide materials, which previously slid into its present location. Slump Block Area _ The landslide block in the western quarter of the site is comprised of a generally medium dense mixture of silt, sand, gravel, and local organic debris. The soils encountered during our subsurface explorations in this area were consistent in relative density and compositional layering, indicating that the block is relatively intact. Furthermore, we did not observe off -sets, settlement, or slumping, within the site or adjacent street areas. The updated probability map by GeoEngineers, dated July 25, 1984, indicates that the relatively level slumped area has `hazards from ground failure in previously failed material,' with a probability of 10 percent occurrence during a 25-year period. This probability was lowered from 35 percent following the placement of area drainage systems. Debris Slide Area The steep slope area extending above the area of the proposed residence is comprised of relatively dense, non -glacial silt overlain by glacial outwash and till. We consider these soils to be of moderate to high strength. We conducted a reconnaissance and limited evaluation of the steep area with Dr. Donald W. Tubbs, LEG, of Tubbs Geosciences.� During our evaluation, we did not observe any evidence of recent/active sloughing of the slope area within the site. However, a relatively recent slide occurred south of the Cornerstone Geotechnical, Inc. p Geotechnical Engineering Report Proposed Single Family Residence _. Edmonds, Washington January 22, 2007 CO File No. 2212 Page 7 property, where a new storm line has since been placed. The slide was a shallow slough event, less than 2 feet in thickness. We understand that this failure was also tied to the construction, and/or draining of a swimming pool located above the top of the slope. Groundwater located at the contact between the pre- ' Vashon sediments and overlying advance outwash, can raise the probability that these slough events will occur. We did not observe evidence of springs or seeps on the steep slope area where the contact between those units was identified. We conducted periodic probing of the soils on the steep slope area above the location of the proposed residence, and found 0.5 to 1.5 feet of relatively loose colluvium overlying dense materials.. Any slough events would likely occur along the contact between the colluvium and underlying material, and are Iexpected to be surficial in nature. This is consistent with the slough failure described above. These types of events are affected by surface water, man-made impacts, and seismic activity. The,risk of sloughing can be minimized if proper drainage is installed, vegetation on the slope is maintained, and yard waste _ and other debris are kept off the slopes. We would expect if a slough event were to occur, it would be 1 very shallow, approximately 1.25 feet in thickness. The updated probability map by GeoEngineers; dated July 25, 1984, indicates that the steep slope area has `hazards from encroaching landslide materials," with a probability of 2 percent occurrence during a 25- year period. It is our opinion, based on the recent surface slide south of the site and the thickness of colluvium on the slope, that the probability of surficial movement is greater than 2 percent. We have recommended the construction of a retaining wall northeast and east of the residence, and/or incorporated into the residential structure. These walls provide catchment of debris derived from failures on the slope above. At this time, there are six trees on the steep slope area that could potentially damage the structure, if they were to fall, and/or be part of a debris slide. The locations of these trees have been surveyed by you, and are shown on the Site Plan in Figure 2. Most of the trees on the slope area have been topped in the last 20 years, and show signs of past cutting as well. We recommend that dead and leaning trees, as well as the trees with a base diameter greater than IS inches, be cut and removed, leaving the root systems intact and in -place. The larger diameter trees would be considered projectiles if a sloughing event occurred, and pose a risk to life and structure. It is typically not feasible to design a retaining wall system to stop high point -load debris, such as trees, from hitting the residence. A debris catchment or netting system can be Cornerstone Geotechnical, Inc. Geotechnical Engineering'Report Proposed Single Family Residence Edmonds, Washington January 22, 2007 CG File No. 2212 Page 8 used to reduce impact on the catchment wall. We can provide details regarding these types of systems upon request. Seismic Hazard It is our opinion, based on our subsurface explorations, that the Soil Profile in accordance with Table 1615.1.1 of the 2003 International Building Code (IBC) is Soil Class 1). We referenced the 2002 map from the US Geological Survey (USGS) website to obtain values for S. and Si. The USGS website. includes the most updated published data on seismic conditions. The seismic design parameters are: SS 123.94% g i Si 43.51% g Fe 1.0 From Table 1615.1.2(1) of the 2003 IBC F, 1.56 From Table 1615.1.2(2) of the 2003 IBC Site specific coefficients and adjusted maximum considered earthquake spectral response acceleration parameters apply as shown in Section 1615.1 of the IBC. Additional seismic considerations include liquefaction potential and amplification of ground motions by ' soft soil deposits. The liquefaction potential is highest for loose sand with a high ground water table. The fine-grained, generally medium dense soils interpreted to underlie the site are considered to have a low ' potential for liquefaction and amplification of ground motion. Seismic activity can reactivate previously slid materials, causing debris flows and large, deep-seated ' failures. The impact that a seismic event would have on the deep seated slide, complex underlying this site is unknown. However, we recommend in. this report that debris catchment walls be designed for ' debris flow materials that could occur during seismic events. ' CONCLUSIONS AND RECOMMENDATIONS . General The underlying slide block and old colluvium appear sufficiently dense and capable of foundation support. However, due to the potential varying conditions in this type of deposit, we recommend that the Cornerstone Geotechnical, Inc. Geotechnical Engineering Report Proposed Single Family Residence Edmonds, Washington January `22, 2007 CG File No. 2212 Page 9 proposed residence be constructed with a stiffened foundation system and at least 2 feet of structural fill . beneath the footings. A retaining wall debris catchment system should be constructed. to protect the residence from debris flows originating up slope. It is our opinion that the block of material on which the residence will be constructed is relatively uniform and intact. The overexcavation and stiffened foundation system will limit the potential for differential settlement and structural distress. The retaining walls north and east of the residence will collect debris that slides from the upper slope area. A portion of the wall can be incorporated into the design of the residence. The adjacent walls should consist of cast- in -place concrete or soldier piles with lagging. We have included recommendations for each type of system.. We recommend removal of the three dead and/or leaning trees and the three. trees greater than 18 inches in diameter, located northeast and east of the proposed residence. These trees have a potential to damage the proposed structure and pose a risk to life and property. These trees are shown on the Site Plan in Figure 2. If constructed as proposed, and following these recommendations, the construction of the proposed residence should not negatively impact or affect. adjacent, neighboring properties. Furthermore, the placement and construction of the retaining wall systems should not affect underground public utilities, and it is our opinion that special measures for their protection are necessary. Cornerstone Geotechnical should observe all grading and excavation activities, including footing excavations, fill placement, and retaining wall construction. Site Preparations and Grading Sitepreparation should be in with the removal of vegetation, topsoil. and an loose material within the i g g � P. � Y building areas. The excavated material should be removed from the site, or stockpiled for later use as landscaping fill. The resulting subgrade should be compacted to a firm, non -yielding condition. Areas observed to pump or weave should be repaired prior to placing hard surfaces. The large -diameter trees should be removed as discussed above, leaving their root systems in -place. Following this procedure, the retaining wall system should be constructed along the base of the steep slope area. ; 0 Cornerstone Geotechnicai, Inc. I Ll I 1 I I I I I 1 I L Geotechnical Engineering Report Proposed Single Family Residence Edmonds, Washington January 22, 2007 CG File No. 2212 Page 10 Most of the on -site soils likely to be exposed during construction are considered moisture sensitive, and the surface will disturb easily when wet. We expect that these soils will be difficult, to compact to structural fill specifications in wet weather. We recommend that earthwork be conducted during the drier months., Additional expenses of wet weather or winter construction could include over -excavation and the use of imported fill or rock spalls. During wet weather, alternative site preparation methods may be necessary. These methods may include utilizing a smooth -bucket trackhoe to complete site stripping and diverting construction traffic around prepared subgrades. Disturbance to the prepared subgrade may be minimized by placing a layer of rock spalls or imported sand and gravel in traffic and roadway areas. Structural Fill General: All fill placed beneath buildings, pavements or other settlement sensitive features should be placed as structural fill. Structural fill, by definition, is placed in accordance with prescribed methods and standards, and is monitored by an experienced geotechnical professional or soils technician. Field observation procedures would include the performance of a representative number of in -place density tests to document the attainment of the desired degree of relative compaction. Materials: Imported "structural fill should consist of a free -draining granular soil, free of organics and other deleterious material, and be well graded to a maximum size of approximately 3 inches. Imported all-weather structural fill should contain no more than 5 percent fines (soil finer than a Standard U.S. No. 200 sieve), based on that fraction passing the U.S. 3/4-inch sieve. The use of on -site soil as structural fill should be limited to pavement areas only, and will be dependent on moisture content _ control. Imported structural fill .should be used beneath all footing areas for the proposed structure. Some drying of the native soils may be necessary in order to achieve compaction. During warm, sunny days this could be accomplished by spreading the material in thin lifts and compacting. Some aeration and/or addition of moisture may also be necessary. Compaction of the native soils to structural fill specifications will be more difficult during wet weather. Fill Placement: Upon overexcavation of at least 2 feet of the fill beneath the footing areas, imported structural fill should be placed in 8- to 10-inch-thick uniform lifts, and each lift should be spread evenly and be thoroughly compacted prior to placement of subsequent lifts. All structural fill underlying building areas, and within a depth of 2 feet below pavement and sidewalk subgrade, should be compacted Cornerstone Geotechnical, Inc. I Geotechnical Engineering Report Proposed Single Family,Residence Edmonds, Washington January 22, 2007 CG File No. 2212 Page 11 to at least 95 percent of its maximum dry density. Maximum dry density, in this report, refers to that density as determined by the ASTM D1557 compaction test procedure. Fillmore than 2 feet beneath sidewalks and pavement subgrades should be compacted to at least 90 percent of the maximum dry density. The moisture content of the soil to be compacted should be within about 2 percent of optimum so that a readily compactable condition exists. It may be necessary to overexcavate and remove wet surficial soils in cases where drying to a compactable condition is not feasible. All compaction should be accomplished by equipment of a type and size sufficient to attain the desired degree of compaction. Temporary and Permanent Slopes Temporary cut slope stability is a function of many factors, such as the type and consistency of soils, depth of the cut, surcharge loads adjacent to the excavation, length of time a cut remains open, and the presence of surface or ground water. It is difficult under these variable conditions to estimate stable temporary cut slope geometry. Therefore, it should be the responsibility of the contractor to maintain safe slope configurations, since the contractor is continuously at the job site, able to observe the nature and condition of the cut slopes, and able to monitor the subsurface materials and groundwater conditions Iencountered. For planning purposes, we recommend that temporary cuts in the fill soils and landslide debris be no steeper than 1.5 Horizontal to 1 Vertical (1.5H:1V). Locally, cuts may stand at a 1H:1V inclination or possibly steeper; however, we should be on -site to make that determination. If ground water seepage is encountered, we would expect that flatter inclinations would be necessary. We do not expect temporary cuts greater than 8-feet tall, or permanent slope configurations steeper than a 2H:IV. We recommend that cut slopes be protected from erosion. Measures taken may include covering cut slopes with. plastic sheeting and diverting surface runoff away from the top of. cut slopes. We do not recommend vertical slopes for cuts deeper than 4 feet, if worker access is necessary. We recommend that cut slope heights and inclinations conform to local and WISHA/OSHA standards. Foundations The on -site colluvium and landslide materials may have inconsistent densities by nature of the deposit. We recommend that foundations be founded on 2 feet of compacted structural fill, and that the foundations be suitably reinforces to allow a foundation span of 10 feet. These measures will reduce the Cornerstone Geotechnical, Inc. L, Geotechnical Engineering Report Proposed Single Family Residence Edmonds, Washington January 22, 2007 CG File No. 2212 Page 12 impact of potential differential settlement of the structure. The structural fill should extend a minimum of 2 feet beyond the edges of the footings in order to create a IH:IV envelope from the base of the footings to the medium dense native soils. Minimum foundation widths should conform to IBC requirements. Standing water should not be allowed to accumulate in footing trenches. All loose or disturbed soil should be removed from the foundation excavation prior to placing concrete. For foundations constructed as outlined above, we recommend an allowable design bearing pressure of 1,500 pounds per square foot (psf) be used for the .footing design. IBC guidelines should be followed when considering short-term transitory wind or seismic loads. The foundations should be reinforced to span -10 feet unsupported to resist potential differential settlement. Standard Retaining Walls The following recommendations are for concrete retaining walls located away from the base of the steep slope area. Subsequent sections provide recommendations for Debris Walls and Soldier Pile Walls, which will be placed along the base of the slope area.. IThe lateral earth pressure acting on retaining walls is. dependent on the nature and density of the soil behind the wall, the amount of lateral wall movement, which can occur as backfill is placed, and the inclination of the backfill. Walls that are free to yield at least one -thousandth of the height of the wall are in an "active" condition. Walls restrained from movement by stiffness or bracing are in an "at -rest" condition. Active earth pressure and at -rest earth pressure can be calculated based on equivalent fluid density. Equivalent fluid densities for active and at -rest earth pressure of 40 pounds per cubic foot (pcf) and 60 pcf, respectively, may be used for design for a level backslope. These values.assume that the on - site soils or imported granular fill are used. for backfill, and that the wall backfill is drained. The preceding values do not include the effects of surcharges, such as due to foundation loads or other surface . loads. Surcharge effects should be considered where appropriate. The above drained active and at -rest values should be increased by a uniform pressure of 53H and 15.OH psf, respectively, when considering seismic conditions. H represents the wall height. The above lateral pressures may be resisted by friction at the base of the wall and passive resistance against the foundation. A coefficient of friction of 0.40 may be used to determine the base friction in the native soils.. An equivalent fluid density of 175 pcf may be used for passive resistance design. To Cornerstone CiWechnical, Inc. I I I I Geotechnical Engineering Report Proposed Single Family Residence Edmonds, Washington January 22, 2007 CG File No. 2212 Page 13 achieve this value of passive pressure, the foundations should be poured "neat" against the native dense soils, or compacted fill should be used as backfill against the front of the footing, and the soil in front of the wall should extend a horizontal distance at least equal to three times the. foundation depth. A factor of safety of 2.0 has been applied to the passive pressure to account for required movements to generate these pressures. The friction coefficient does not include a factor of safety. All wall backfill should be well compacted. Care should be taken to prevent the buildup of excess lateral soil pressures due to overcompaction of the wall backfill. Debris Walls The retaining wall incorporated into the single family residence should be designed to support additional material that could slide against it in the event of a shallow debris flow. Additional concrete walls or a soldier pile and lagging system should be used along the base of the slope where the residence is located within 30 feet of the slope, or if landscaping protection is desired. Based on our visual assessment and local probing of the colluvium on the face of the steep slope face, we estimate an average depth of 1.25 feet of material that could slide toward the residence. This results in a volume of 3.99 cubic yards per lineal foot of slope, measured across the slope at any given elevation below the elevation of the largest trees. This results in a wall height of 12.5 feet above the base of the adjacent slope area. We have used a 10 degree backslope in our calculation of height, This height does not include a factor of safety. However, we would expect some deflection sideways along,the wall which would reduce the total height. This assumes a large portion of the slope does not move at once. Where the wall can be moved away from the slope 3 feet, this wall height can be reduced to 8 feet. Where the house is cut into the slope, the corner of the structure forms an apex into the slope. This would help deflect debris reducing the total height. We consider reducing the 12.5 feet to 10 feet'appropriatefor this. This could be lowered even more if a slope debris catchment system, as discussed in a subsequent section, is used. Our calculations indicate that debris would flow a horizontal distance of approximately 25 feet from the base of the steep slope area. We recommend construction of a wall system in areas where the proposed residence will be located 30 feet or less from the steep slope. A slope debris catchment system in conjunction with the retaining wall would further reduce the risk of damage to the structure from falling debris. Cornerstone Geotechnical, Inc. Geotechnical Engineering Report Proposed Single family Residence Edmonds, 'Washington January 22, 2007 CG File No. 2212 Page 14 The portion of the retaining wall that will provide catchment for sliding debris should be designed using equivalent fluid densities for active and at -rest earth pressure of 85 pounds per, cubic foot (pcf) and 105 pcf, respectively. An equivalent fluid density of 125 pcf maybe used for passive resistance design. Soldier Pile Walls Active pressure acting on the piles and lagging for design of soldier piles should be calculated based on a triangular pressure distribution equivalent to that exerted by a fluid with a density of 40 pcf. This pressure acts on the full center -to -center pile spacing above the base of the cut. It has been shown that lagging does not experience the full soil pressure; therefore, 1/2 of the active pressure can be used for the design of the timber lagging. The passive resistance is considered to be a triangular distribution, equivalent to that exerted by a fluid. The maximum passive resistance at the bottom of the pile is the product of the passive resistance, coefficient and the depth of the pile below the base of the excavation. The passive resistance coefficient used for design should be 300 pcf, assuming a level ground surface at the base of the planned excavation. This can be considered to act on 2.effective pile diameters, or the pile spacing, whichever is less, below the base of the cut. No safety factors have- been applied to the above passive resistance value. Appropriate safety factors should be applied in the design of the shoring system. We suggest that a safety factor of 2 be applied to the passive resistance value. The portion of the retaining wall that will provide catchment for sliding debris should be designed using equivalent fluid densities for active and at -rest earth pressure of 85 pounds per cubic foot (pcf) and 105 pcf, respectively. An equivalent fluid density of 300 pcf may be used for passive resistance design. Slope Debris Catchment There are slope catchment systems that can slow or stop debris flows prior to impacting the retaining walls. These systems would add additional safety factor in protection of the structure and also could be used to lower the debris wall heights. We have obtained data on a system produced by Geobrugg. This system essentially anchors a debris catchment net placed over the slope. A debris catchment fence placed on the slope near the base would prevent a majority of material from hitting the house. These systems are typically expensive, and may not be as cost=effective as retaining wall systems. The cost of these systems should be weighed against the added protection they provide to the residence. We can provide information on these types of systems upon request. Cornerstone Geotechnical, Inc. Geotechnical Engineering Report Proposed Single Family Residence Edmonds, Washington January 22, 2007 CG File No. 2212 i Page 15 Slabs -On -Grade Slab -on -grade areas should be prepared as recommended in the Site Preparation and Grading subsection. Slabs should be supported on 1 to 2 feet of structural fill placed on the underlying medium dense silty sands. Where moisture control is a concern, we recommend that slabs be underlain by 6 inches of free -draining coarse sand or pea gravel for use as a capillary break. A suitable vapor barrier, such as heavy'plastic sheeting, should be placed over .the capillary break. An additional 2-inch-thick damp sand blanket can be used to cover the vapor barrier to protect the membrane and to aid in curing the concrete. This will also help prevent cement paste bleeding down into the capillary break through joints or tears in the vapor barrier. The capillary break material should be connected to the footing drains to Iprovide positive drainage. Erosion and Sediment Control Erosion and sediment control (ESC) is used to minimize the transportation of sediment to wetlands, streams, lakes, drainage systems, and adjacent properties. Erosion and sediment control measures should be taken and these measures should be in general accordance with local regulations. At a minimum, the following basic recommendations should be. incorporated into the design of the erasion and sediment control features of the site: 1) Phase the soil, foundation, utility, and other work, requiring excavation or the disturbance of the site soils, to take place during the dry season (generally May through September). However, provided precautions are taken using Best Management Practices (BMP's), grading activities can be undertaken during the wet season (generally October through,April). It should be noted that this typically increases the overall project cost. 2) All site work should be completed and stabilized as quickly as possible. 3) Additional perimeter erosion and sediment control features may be required to reduce the possibility of sediment entering the surface water. This may include additional silt fences, silt fences with a higher Apparent Opening Size (AOS), construction of a berm, or other filtration systems. 4) Any runoff generated by dewatering discharge should be treated through construction of a sediment trap if there is sufficient space. If space is limited, other filtration methods will need to be incorporated. Cornerstone Geotechnical, Inc. Geotechnical Engineering Report Proposed Single Family Residence Edmonds, Washington January 22, 2007 CG File No. 2212 Page 16 Drainage We recommend that runoff from impervious surfaces, such as roofs, driveway and access roadways, be collected and routed to an appropriate storm water discharge system. We suggest that the finished ground surface be sloped at a gradient of 3 percent minimum for a distance of at least 10 feet away from the _ buildings, as indicated in IBC Section 1803.3. Surface water should be collected by permanent catch basins and drain lines, and be discharged into a storm drain system. We recommend that footing drains be used around all of the structures where moisture control is important. The underlying silty soils may pond water that could accumulate in crawlspaces. It is good practice to use. footing drains installed at. least 1 foot below the planned finished floor slab or crawlspace elevation to provide 'drainage for the crawlspace. At a minimum, the crawlspaces should be sloped to drain to an outlet tied to the drainage system. We recommend that all drainlines extend away from the steep slope in the east part of the site and connect to a catchbasin south or southwest of the residence. If drains are omitted around slab -on -grade floors where moisturecontrol is important, the slab should be a minimum of 1 foot above surrounding grades. Where used, footing drains should consist. of 4-inch-diameter, perforated PVC pipe that is surrounded by free -draining material, such'as pea gravel. Footing drains should discharge into tightiiries leading to an appropriate collection and discharge point. Crawlspaces should be sloped to drain, and a positive connection should be made into the foundation drainage system. For slabs -on -grade, a drainage path i should be provided from the capillary break material to the footing drain system. Roof drains should not be connected to wall or footing drains. Pavement The performance of roadway pavement is critically related to the conditions of the underlying subgrade. We recommend that the subgrade soils within the roadways be treated and prepared as described in the Site Preparation and Grading subsection of this report. Prior to placing base material, the subgrade soils should be compacted to a non -yielding state with a vibratory roller compactor and then proof -rolled with a piece of heavy construction equipment, such as a fully -loaded dump truck. Any areas with excessive weaving or flexing should be overexcavated and recompacted or replaced with a structural fill or crushed rock placed and,compacted in accordance with recommendations provided in the Structural Cornerstone Geotechnical, Inc. Geotechnical Engineering Report Proposed Single Family Residence Edmonds, Washington January 22, 2007 CG File No. 2212 Page 17 Fill subsection of this report. We would anticipate local overexcavations of up to 3 feet within the proposed driveway areas. CONSTRUCTION OBSERVATION We should be retained to provide observation and consultation services during construction to confirm that the conditions encountered are consistent with those indicated by the explorations, and to provide recommendations for design changes, should the conditions revealed during the work differ from those anticipated. As part of our services, we would also evaluate whether or not earthwork and foundation installation activities comply with contract plans and specifications. USE OF THIS REPORT We have prepared this report for Mr. Ron Hilliard and his agents, for use in planning and design of this project. The data and report should be provided to prospective contractors for their bidding and estimating purposes, but our report, conclusions and interpretations should not be construed as a warranty of subsurface conditions. The scope of our services does not include services related to construction safety precautions, and our recommendations are not intended to direct the contractors' methods, techniques, sequences or procedures, except as specifically described in our report, for consideration in design. There are possible variations in subsurface conditions. We recommend that project planning include contingencies in budget and schedule, should areas be found with conditions that vary from those described in this report. Within the limitations of scope, schedule and budget for our services, we have strived to take care that our services have been completed in accordance with generally accepted. practices followed in this area at the time this report was prepared. No other conditions, expressed or implied, should be understood. .•. Cornerstone Geotechnical, Inc. Geotechnical Engineering Report Proposed Single Family Residence Edmonds, Washington January 22, 2007 CG File No: 2212 Page 18 We appreciate the opportunityto be of service to you. If there are any questions concerning this report or if we can. provide additional services, please call. Sincerely, Cornerstone Geotechnical, Inc. f Wasb. �a f0 c 756 \y @sed Ggo�oA Donald W. Tubbs . Donald W. Tubbs; PhD., L.E.G. Consulting Engineer Geologist I/XPL/07 Charles P. Couvrette, PE Principal Engineer CPC -.am Three Copies Submitted Seven Figures. Information about this Geotechnical Engineering Report Cornerstone Geotechnical, Inc. Vicinity Map N G H i A B C D E F 3 Z M NEES, 4 0- , nAM, V � L1. "0 5 I kj� -gm g-, �Y * AV , 41 Project` Site 6 ok.. G THi� !; ME Mv _0 r 7 S. M drJORMIN MWAMEMEEM-iAmMena CornerstonePhone. (425) 844-1977 Hilliard Single -Family Residence Fax (425) 844-1987 11111111111,M] Geotechnical, Inc. File Number Figure qw 17625-130th Ave NE, C-102 - Woodinville, WA - 98072 2212 1 1!M 33" Leaning (Extmm#1 split in and Leaning A oe 1-r ad) Leaning //ice01 Lid LO ROAD Reference: Based on undated site plan provided by Client I Site Plan LEGEND TP-1 Number and Approximate Location of Test Pit �e Location of .Tree (Surveyed) — with Approximate Trunk Size Topographic Line 0 20 40 i I i I I Scale 1 ° = 20' Cornerstone Phone: (425) 844-1977 Hilliard SFR Far (425) 844-1987 ljo Geotechnical, Inc. File Number Ir igure 17625-130th Ave NE, C-102 • Woodinville, WA- 98072 2212 2 o e p@ � M :a I 3. i m W a b� •N � � N ro � 'C1 a $ I C) co o O V h CI-0 V - O —11 -r W Q vy Q Y., 1 m Nt tcc •� y co C !V �p O r1 la- to C`1 V co to 11 C G Ce-L-L i t �� z co CD m m Y3 a s o o `'�'' ►� �m zz O)o "' E CO �c Lo m � o f U - i � •ro - ic�oq ) t p e G> laN •x U O o . c .c" a a `� a a a a vJ 0 pp. oa N ♦♦W� W m W O� N C N � � i y N 7L ro a = z caro m IL a .y m m.°CD cooil O cc cz o. ° a yv o U. d �♦ �qp C h h 1100 V O_ U ccm 0 co co L(D i a 0 . Q� LD a q ci m •� CC N pa :° �Xvo - O :c •` Q$ pp Qry TT pQ w Col- Q v! Un.ified.Soil Classification System MAJOR DIVISIONS GROUP GROUP NAME SYMBOL COARSE- GRAVEL CLEAN GRAVEL GW WELL -GRADED GRAVEL, FINE TO COARSE GRAVEL GP POORLY -GRADED GRAVEL GRAINED MORE THAN 50% OF COARSE FRACTION GRAVEL SOILS. RETAINED ON NO. 4 SIEVE WITH FINES GM SILTYGRAVEL GC' CLAYEY GRAVEL MORE THAN 50% SAND CLEAN SAND SW RETAINED ON number 200 SIEVE WELL -GRADED SAND, FINE TO COARSE SAND MORE THAN 50% OF SP POORLY -GRADED SAND COARSE FRACTION SAND PASSESN0.4SIEVE VVI TH I FINES SM SILTY SAND Sc CLAYEY SAND SILTAND CLAY INORGANIC ML SILT FINE - GRAINED LIQUID LIMIT LESS THAN 56% CL CLAY SOILS ORGANIC OL ORGANIC SILT, ORGANIC CLAY MORE THAN 50% PASSES NO. 200 SIEVE SILTAND CLAYINORGANIC MH SILT OF HIGH PLASTICITY, ELASTIC SILT CH CLAY OF HIGH PLASTICITY, FAT CLAY. LIQUID LIMIT 60% OR MORE ORGANIC OH ORGANIC CLAY, ORGANIC SILT HIGHLY ORGANIC SOILS PT PEAT NOTES: SOIL MOISTURE MODIFIERS 1) Field classification Is based on Dry -Absence of moisture, dusty, dry visual examination of soil in general to the touch accordance with ASTM D 2488-83. 2) Soil classification using laboratory Moist- Damp, but no visible water tests is based on ASTM D 2487-83. Wet- Visible free water or saturated, 3) Descriptions of soil density or usually soil is obtained from Consistency are based on below water table interpretation of blowcount data, visual appearance of toils, and/or test data. Cornerstone Phope: (425) 844-.1977 Unified Soil Classification System Geotechnical, Inc. Fax: (425 . )84.4-1087 17. 1625-130th Ave NE, C-1 02 - Woodinvi - Ile, WA* 98072 Figure 5 I LOG OF EXPLORATION DEPTH USC SOIL DESCRIPTION TEST PIT ONE 0.0 - 4.0 SM LIGHT BROWN SILTY FINE TO MEDIUM SAND WITH TRACE GRAVEL (LOOSE TO MEDIUM DENSE, DRY) (SLIDE DEBRIS) -INCREASED FINES BELOW 2.0 FEET -ROOTLETS OBSERVED BELOW 2.0 FEET 4.0 - 7.0 SM LIGHT BROWN SILTY FINE TO MEDIUM SAND (MEDIUM DENSE, DRY) (SLIDE DEBRIS) -VERY WEAK CEMENTATION OBSERVED AT 4.0 FEET -NO CEMENTATION OBSERVED BELOW 5.0 FEET 7.0 - 8.0 SP REDDISH BROWN FINE TO COARSE SAND WITH TRACE GRAVEL (LOOSE TO MEDIUM DENSE, MOIST) (SLIDE DEBRIS) 8.0 - 9.0 SM LIGHT BROWN SILTY FINE TO MEDIUM SAND (LOOSE TO MEDIUM DENSE, MOISn'(SLIDE DEBRIS) -TRACE ORGANICS (WOOD DEBRIS) FOUND AT 8.0 FEET 9.0 -10.5 SP REDDISH BROWN FINE TO COARSE SAND WITH TRACE GRAVEL (LOOSE TO MEDIUM; MOIST) (SLIDE DEBRIS) 10.5 -13.0 SM LIGHT BROWN SILTY FINE SAND WITH TRACE GRAVEL (LOOSE TO MEDIUM DENSE, MOIST) (SLIDE DEBRIS) SAMPLES WERE COLLECTED AT 2.5, 4.0, 7.0, 8.0, AND 9.5 FEET GROUNDWATER SEEPAGE WAS.NOT ENCOUNTERED TEST PIT CAVING WAS ENCOUNTERED AT 10.5 FEET TEST PIT WAS COMPLETED TO 13.0 FEET ON 10-25-06 TEST PIT TWO 0.0 - 3.0 SM LIGHT BROWN SILTY FINE TO MEDIUM,SAND WITH TRACE GRAVEL AND ORGANICS (LOOSE TO MEDIUM DENSE, MOIST) (FILL) -SMALL LAYERS (6 INCHES OR LESS THICKNESS) OF REDDISH BROWN SILTY FINE TO MEDIUM SAND WITH TRACE GRA VEL -BURIED ORGANICS (ROOTS, DEBRIS) BELOW SURFACE 3.0 - 4.0 SM DARK BROWN SILTY FINE TO MEDIUM SAND WITH ORGANICS (LOOSE TO MEDIUM DENSE, MOIST) (BURIED TOPSOIL LAYER) BURIED TOPSOIL LAYER DIPS APPROXIMATELY 5 DEGREES TO THE NORTH 4.0 - 7.0 SM LIGHT BROWN SILTY FINE TO MEDIUM SAND (LOOSE TO MEDIUM DENSE, MOIST) (SLIDE DEBRIS) 7.0 -13.0 ML GRAY, RUST -MOTTLED SANDY SILT WITH TRACE GRAVEL (STIFF TO VERY STIFF, MOIST) (SLIDE DEBRIS) -ORGANICS (ROOTS) OBSERVED AT &0 FEET -MOTTLING MORE DISTINCT BELOW 10.0 FEET 13.0 -14.0 SM GRAY RUST MOTTLED SILTY VERY FINE TO FINE SAND (LOOSE TO MEDIUM DENSE, MOIST) (SLIDE DEBRIS) SAMPLES WERE COLLECTED AT 2,5, 7.0, 12.0. AND 14.0 FEET GROUNDWATER SEEPAGE WAS NOT OBSERVED TEST PIT CAVING WAS NOT OBSERVED TEST PIT WAS COMPLETED TO 14.0 FEET ON 10-25-08 CORNERSTONE GEOTECHNICAL, INC. FILE NO 2212 FIGURE 6 ! LOG OF EXPLORATION ' DEPTH i USC SOIL DESCRIPTION TEST PIT THREE 0.0 - 6.0 SM DARK BROWN TO GRAY SILTY FINE TO MEDIUM SAND WITH GRAVEL (LOOSE, TO MEDIUM DENSE, MOIST) (FILL) I-ROOTLETS OBSERVED AT 4.0 FEET 5.0 - 6.5 SM DARK BROWN SILTY FINE TO MEDIUM SAND. WITH TRACE GRAVEL AND ROOTS (LOOSE TO MEDIUM DENSE, MOIST) (BURIED TOPSOIL LAYER) BURIED TOPSOIL LAYER DIPS - APPROXIMATELY 5 DEGREES TO THE I NORTH # -ORGANICS (STUMP) FOUND AT 6.0 FEET 6.5 -14.0 SM GRAY RUST MOTTLED SILTY FINE SAND WITH TRACE GRAVEL AND ROOTS (LOOSE TO MEDIUM DENSE) (SLIDE DEBRIS) SAMPLES WERE COLLECTED AT 1.5, 8.0,12.0, AND 14.0 FEET GROUNDWATER SEEPAGE WAS NOT OBSERVED TEST PIT CAVING WAS NOT OBSERVED TEST PIT WAS COMPLETED TO 14.0 FEET ON 10-25-06 I TEST PIT FOUR f 0.0 - 8.5 ML LIGHT BROWN FINE SILT (STIFF TO VERY STIFF, DRY) (PRE-FRASER DEPOSITS) I - LAMINATION PRESENT ON SCARP. SURFACE - BLOCKY TEXTURE OBSERVED -FALLING MATERIAL WAS OBSERVED ABOVE TEST PIT LOCATION I 8.5 -10.0 SM LIGHT BROWN SILTY FINE TO MEDIUM SAND WITH ROOTS (LOOSE TO MEDIUM DENSE, MOIST) (BURIED PRE-VASHON DEPOSITS AND SLIDE DEBRIS CONTACT) -CONTACT PLANE DIPS APPROXIMATELY 60 DEGREES TO THE SOUTH 10.0 -15.5 SM LIGHT BROWN TO BROWN SILTY FINE TO MEDIUM SAND WITH TRACE GRAVEL AND ROOTS (LOOSE TO MEDIUM DENSE, MOIST) (SLIDE DEBRIS) I SAMPLES WERE NOT COLLECTED GROUNDWATER SEEPAGE WAS NOT OBSERVED TEST PIT CAVING WAS NOT OBSERVED TEST PIT WAS COMPLETED TO 15.5 FEET ON 10-25-06 CORNERSTONE GEOTECHNICAL, INC. FILE NO 2212 FIGURE 7 r7'GM`OI,e�h.HICflI. Engineering Repor t � Geotechnical Services Are Performed for Specific Purposes, Persons, and Projects Geotechnical engineers strur�,re their services to meet the specific needs of their clients. A geotechnical engineering study conducted for a civil engi- neer may not fulfill the needs of a construction contractor or even another civil engineer. Because each geotechnical engineering study is unique, each geotechnical engineering report is unique, prepared solelyforthe client No one except you should; rely on your geotechnical engineering reportwithout first conferring with the geotechnical engineer Who prepared it And no one not even yod —should apply the report for any purpose or project except the one originally contemplated. Read the RM Report Serious problems have occurred because those relying on a geotechnical engineering report did not read it all. Do not rely on an executive summary. Do not read selected elements only. A Geotechnical Engineering Report Is Based on A WNW. Set of Project -Specific Factors Geotechnical engineers consider a number of unique, project, specific fac- tors when establishing the scope of a study. Typical factors include: the client's goals, objectives, and risk management preferences; the,general nature of the stnrcture involved, it size, and configuration; the location of the strucWre on the site; and otrr her planned or existing site improvements, such as access roads, parking lots; and underground utiliiies.'Unless the geotechnical engineer who conducted the study specifically indicates oth- erwise, do not rely on a geotechnical engineering report that was: • not prepared for you, • not prepared for your project, • not prepared for the specific site explored, or • completed before important project changes were made. Typical changes that can erode the reliability of an existing geotechnical engineering report.include those that affect. • the function of the proposed structure, as when it's changed from a parking garage to an office building, or from a light industrial plant to a refrigerated warehouse, • elevation, configuration, location, orientation, or weight of the proposed structure, • composition of the design team, or • project ownership. As a general cute, attiw inform your geotechnical engineer of project changes ---even minor ones -and request an assessment of their impact. Geote wical engineers cannot accept responsfbilrty or liability for problems fhatoc occur meirrepo& do not consider developments of which they were notinfnrmed Subsurface Conditions Can Change A geotechnical engineering report is based on conditions that existed at the time. the study was performed. Do not rely on a geoteehnica/ engineer- ing reporfwhose adequacy may have been affected by. the passage of lime; by marFinade events, such as construction on or adjacent to the site; or by natural events, such as floods, earthquakes, or groundwater fluctua- tions. Ahsayscontact the geotechnical engineer before applying the report to determine 9 it is still reliable. A minor amount of additional testing or analysis could prevent major problems. Most Geotechnical Find -rags Are Professional Opinions Site exploration identifies subsurface conditions only at those points where subsurface tests are conducted or samples are taken. Geotechnical engi- . neers review field and laboratory data and then apply their professional. judgment to render an opinion, about subsurface conditions throughout the site. Actual subsurface conditions may differ= -sometimes significantly — from those indicated in your report. Retaining the. geotechniml engineer who developed your report to provide construction observation is the most effective method of managing the risks associated with unanticipated conditions. A Reports Recommendations Are Not Final Do not overiely on the construction recommendations included in your report. Those recammendatlons are not final, because geotechnical engi- neers develop them principally from judgment and opinion. Geotechnical engineers can finalize their recommendations only by observing actual subsurface conditions revealed during construction. The geotechnical engineer who developedyour report cannot assume responsibility or liability for the report's recommendations if that engineer does not perform construction observation. A Geotechnical Engineering Report Is Subject, to Misinterpretation . Other design team members' misinterpretation of geotechnical engineering reports has resulted in costly problems. Lower that risk by having your geo- technial engineer confer with appropriate members of the design team after report: Also retain y submitting the report: geotechnical engineer to review perti- nent elements of the design team's plans and specifications. Contractors an also misinterpret a geotechnical engineering report Reduce that risk by having your geotechnical engineer participate in prebld and preconstruction conferences, and by providing construction observation. Do Not Redraw the Etgineer's Logs Geotechnial engineers prepare final boring and testing logs based upon their interpretation of field logs and laboratory data. To prevent errors or omissions, the logs included in a geotechnical engineering report should neverbe redrawn for inclusion in architectural or other design drawings. Only photographic or electronic reproduction is acceptable, butmcognkze that separating logs from the report can elevate risk Give Contractors a Complete Report and Guidance Some owners and design professionals mistakenly believe they can make contractors liable for unanticipated subsurface conditions by limiting what they provide for bid preparation. To help prevent costly problems, give con- tractors the complete geotechnical engineering report, butpreface it with a clearly written letter of transmittal. In that letter, advise contractors that the report was not prepared for purposes of bid development and that the report's accuracy is limited; encourage them to confer with the geotechnical engineer who prepared the report (a modest fee may be required) and/or to conduct additional study to obtain the specific types of information they need or prefer. A prebid conference can also be valuable. Be sure contrac- tors have sufficient time to perform additional study. Only then might you be in a position to give contractors the best information available to you, while requiring them to at least share some of the financial responsibilities stemming from unanticipated conditions. Read Responsibility Provisions Closely Some clients, design professionals, and contractors do not recognize that geotechnical engineering is far less exact than other engineering disci- plines. This lack of understanding has created unrealistic expectations that have led to disappointments, claims, and disputes. To help reduce the risk of such outcomes, geotechnical engineers commonly include a variety of explanatory provisions in their reports. Sometimes labeled 'limitations' many of these provisions indicate where geotechnical engineers' responsi- bilities begin and end, to help others recognize their own responsibilities and risks. Read these provisions closely. Ask questions. Your geotechnical engineer should respond fully and frankly. Geoenvbeonmental Concerns Are Not Cowered The equipment, techniques, and personnel used to perform a geoenviron- mental study differ significantly from those used to perform a geotechnical study. For that reason, a geotechnical engineering report does not usually relate any geoenvironmentat findings, conclusions, or recommendations; e.g., about the likelihood of encountering underground storage tanks or regulated contaminants. Unanticipated environmental problems have led to numerous project fat7ures. If you have not yet obtained your own geoen- vironmental information, ask your geotechnical consultant for risk man- agement guidance. Do not rely on an environmental report prepared for someone else. Obtain Professional Assistance To Deal with Mold Diverse strategies can be applied during building design, construction, operation, and maintenance to prevent significant amounts of mold from growing on indoor.surfaces. To be effective, all such strategies should be devised for the express purpose of mold prevention, integrated into a com- prehensive plan, and executed with diligent oversight by a professional mold prevention consultant Because just a small amount of water or moisture can lead to the development of severe mold infestations, a num- ber of mold prevention strategies focus on keeping building surfaces dry. While groundwater, water infiltration, and similar issues may have been addressed as part of the geotechnical engineering study whose findings are conveyed in this report, the geotechnical engineer in charge of this project is not a mold prevention consultant; none of the services per- formed In connection with the geotechnical engineer's study were designed or conducted for the purpose of mold proven - lion. Proper implementation of the recommendations conveyed in this report will not of itself he sufficient to prevent mold from growing in or an the structure involved. Rely, on Your ASFE-Member Geotechncial BOeer for Additional Assistance Membership in ASFE/The Best People on Earth exposes geotechnical engineers to a wide array of risk management techniques that an be of genuine benefit for everyone involved with a construction project Confer with you ASFE-member geotechnical engineer for more information. ASFE The Rest feasts on Earth 8811 Colesville Road/Suite G106, Silver Spring, MD 20910 Telephone:301/5fi5-2733 Facsimile:301/589-2017 e-mail: infodWe.org www.asio.org Copyright 2004 by ASFE, inc. Duplication, reproduction, or copying of this document N whale orin park by arty means whatsoever is siricUy prohibited, except with ASFE'a apefc wdtten permission Excerpting, quoting, or 0Merwlse exbacbhg wording from this document is permitted only with the express written permission of ASFE, and only for purposes of scholarly research or book reWew. only members orASFEmay use Urns document as a complement to or as an element of a geotechr}ical engineering report Any other rum, individual, or other entity that so uses this document without being an ASFE member could be Committing negggent or Intentional (haudulent) misrepresentation. 11GER06045.0M 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 J. C. Mc DONNELL & ASSOCIATES CONSULTING CIVIL ENGINEERS* P.O. Box 13199 Mill Creek, WA. 98082 STORM DRAINAGE STUDY For RON HILLIARD SFR Located at 156th & 75t' Place West Edmonds, WA. 98020 DEVELOPER: Mr. Ron Hilliard, PLS 2083123rd Avenue W Lynnwood, WA. 98036-7804 Issue Date: February 1, 2007 PREPARED BY: J. C. McDonnell, PE Surveyor of Record: PGS Inc. 6608- 216th Street SW Ste 304 Mountlake Terrace, WA 98043 Tel:(425) 778-5620 RECEIVED DEC 18 Z007 BUILDING DEPT. J.C. Mc DONNELL & ASSOCIATES CONSULTING CIVIL ENGINEERS P.O. Box 13199 Mil[ Creek, WA. 98082 STORM DRAINAGE STUDY For RON HILLIARD SFR Located at 156th & 751h Place West Edmonds, WA. 98020 DEVELOPER: Mr. Ron Hilliard, PLS 2083123d Avenue W Lynnwood, WA. 98036-7804 Issue Date: February 1, 2007 PREPARED BY:' J. C. McDonnell, PE Surveyor of Record: PGS Inc. 6608- 216`h Street SW Ste 304 Mountlake Terrace, WA 98043 Tel:(425) 778-5620 t r EXECUTIVE SUMMARY The proposed project is an undeveloped lot located at the Northeast Quadrant of the intersection of 75`h Place W and the unopened ROW for 156`h Street SW in Edmonds, WA. 98020. The Legal Description places the property in Section 05, Township 27N, Range 03E, WM. The existing site consists of a graded building site abutting a steep embankment identified as the Meadowdale slide area. The property consists of two (2) adjacent parcels abutting the Meadowdale Beach County Park on the north. Sewer, water, telephone and power utilities are available in the street. 'Detention for this Single Family residence will be conventional underground concrete vault sized by the pertinent Edmonds regulation for a house of this size (3.800 SF new im9ervious) with an internal restrictor and pipe conveyance to the public storm drain in 75 Place W. Conventional frontage improvements might be required along by the City of Edmonds but the status is unknown at this time. The existing right-of-way measures 40-feet total, twenty feet (20) from the existing ROW centerline to the subject property line. No additional dedications have been required as of this writing. Runoff from the lot will be metered into the public storm drain in 73`d Place and will be conveyed through pipes to Puget Sound to protect shoreline properties from erosion WATER QUALITY AND TESC METHODS PROPOSED M Type of water quality measure(s) proposed: l . DOE Standard erosion control BMPs will be designed at the detailed construction plan stage such as mulch, seed, hay bales, sediment traps, plastic sheeting, sediment ponds and TESC entrances to control construction runoff, as required. . 2. Mulching and other winter soil management techniques will be specified in the construction plans. 11 I I IJ.C.McDonnell & Associates 11 1 1 LI 1 EXISTING CONDITIONS The site is the last vacant lot at the end of 76`h Place West. The site is bordered on the north with the Meadowdale County Park, to the east by a steep slope two hundred to three hundred feet high and to the south by an existing house and an unopened ROW identidfied as 156t' Street SW. The site is bordered to the west by 76th Place and a single line of houses. Beyond the houses the terrain dives sharply to the beach. In the past a building pad was fashioned at the toe of the steep slope. The site is in reasonably good and stable condition with few significant trees. The trees along the eastern edge of the building envelope the south line will probably not be impacted by the development. The Snohomish County Soil Survey lists the site soil type as Alderwood Gravely Sandy Loam with 0 to 8 percent slopes. The Gravely Sandy Loam corresponds to a type "C" soil with CN's of 81 to 85 depending upon the vegetation and cover conditions. Parcel Legal Description Section 05 Township 27 Range 04 Quarter NW LUNDS MEADOWDALE TRS BLK 000 D-01 TH PTN LOT 1 LY E OF E LN EXST CO RD TGW TH PTN VAC 73RD AVE W AS VAC UND CITY OF ED ORD NO 3201 REC UND AFN 9806030195 I J.C.McDonnell & Associates Ll DEVELOPED SITE CONDITIONS The proposed project will construct approximately 3,790 SF of new rooftop and driveway surfaces to 0.327 acres of land. The area of the immediate building lot is 0.327 Acres. The development requires detention but perhaps not water quality treatment since the paved surfaces will be a 12-foot x 20-foot driveway and a covered garage. Total exposed driveway surface will be 440 SF. The detention is designed from Tables provided by the City of Edmonds providing standard storage volumes based upon the square footage of impervious to be constructed. The downstream storm catch basin at the corner of 76 Place W and the unopened R/W of 156`h Street will be the targeted discharge point. The lot will be provided with two (2) 12" yard drains connected by 6" PVC pipe to serve the roof downspout drain system. Footing drains of the new houses shall be connected to the system downstream of the detention system, . NO . 41t s Amer ee- ,n AeeuoAk o �+ wafer sGr4/(he /ou fed �ro C'��y.rfor.� �pydej/aKc es. i:�S 4/,f/u8. City requirements for frontage improvements will be developed during the preliminary SEPA process and may be added to the final working drawings later if required. To date no requirement for improvements in the 40' ROW have been indicated. Temporary erosion control BMP's will be required to control erosion and potential silt production off the construction area until the site is stabilized and the landscaping is in place. 1, I I I 4 J.C.McDonnell &Associates u 1 1 LJ I SITE HYDRAULIC ANALYSIS Revised 9/22/05 The detention for the site will be conventional concrete tank, a 750 Gal septic tank, modified with a restrictor, an overflow stand pipe and an outlet orifice per Edmonds standards. The restrictor will be small diameter pipe and shall be fabricated from 4" PVC pipe and fittings. Total Property Area (2-lots) = 0.73Acres, Development Area = 0.327 Acres Existing Pervious = 0.327 Acres Existing Impervious Area = 0.000 Acres Proposed Impervious = 0.087 Acres Proposed Pervious = = 0.240 Acres Rooftop Impervious Area = 3,360 SF Access Drive Impervious = 440 SF Total Created Impervious Surface = 3,800 SF IA. DESIGN CRITERIA 1 11 I 1 The City of Edmonds Drainage Ordinance requires that storm water from new impervious surfaces created by development must be detained. The Drainage System Standard Plans further provides that if impervious development is less that the 5,000 sf threshold, a standard pre -tabulated City Drainage table can be used to develop the required storage volume. This site is ineligible for the Standard Plans. Specifically, the ordinance requires that "a retention control device must be provided in order to maintain surface water discharge rates at or below the 25-year, 6-hour rainfall event." It is further requires that the "retention/detention facility must be constructed to store the runoff from a 100-year, 12- hour rainfall event." The code allows the City Engineer to accept different but equivalent standards. . B. DETENTION VOLUME With Impervious area ,= 3800 SF Detention Required = 95 CF (interpolated) = 710.6 Gal. Modified "750" Gal Septic Tank Inside L = 5.417' Inside W = 4.75 ` Depth = 5.08' Volume = 130.7 CF = 977.73 Gal available Air Space = 0.5' = 96.2 Gal Detention Volume = 3.68' = 708.3 Gal Dead Storage = 0.90' =173.2 Gal Restrictor size = 3/4" per City of Edmonds ' S J.C.McDonnell &Associates 1 1 fJ I 1 1 DOWNSTREAM CONDITIONS Site detention will discharge by a 6" pipe conveyance to an existing CB in the Public ROW. This CB releases to a 6" pipe to the south on 76`h Place West for 133 LF to a Public Storm Drain. The public Storm is 12" RCP to the south to the low point in 76 h and then West to Puget Sound. The 6" SD should be upgraded to a minimum 8" pipe to accommodate the Lot development drainage and the runoff from the steep slope to the east. 6 J.C.McDonnell & Associates 1 C r n v 1 ENGINEERING REPORT APPENDICES J.C.McDonnell & Associates Snohomish County, WA Assessor Parcel Data Page 1 of 2 SnolhomishOnline Government tnfOrnaUon & Services lCounty4* WashingWn CR E A L *Property Information ountyHome Assessor Home Treasurer Home Information on which Department to contact Please view Disclaimer If you have questions, comments or suggestions, please Contact Us. Date/Time:1/15/2007 9:36:37 AM Answers to Frequently Asked Questions about Parcel Data (opens as new window) Return to Property Information Entry page Parcel Number 00500900000101 Prev Parcel Reference 50090000010108 A sctl.7 99 c- ia �� t2tZda `- View —Map of this parcel (opens as new window)(L-'G General Information Taxpayer Name 11 Address (contact the Treasurer if you have questions) HILLIARD RONNIE G & SUSAN A 11 2083123RD AVE W--- LYNNWOOD, WA 98036-7804 If the above mailing address is incorrect and you want to make a change, see the information on Name and Address Changes Owner Name 11 Address (contact the Assessor if you have questions) HILLIARD RONNIE G & SUSAN A 11 2083123RD AVE W--- LYNNWOOD, WA 98036-7804 If the above name and address is incorrect due to a recent sale, please see the information on Name and Address Changes After a Sale Street (Situs) Address (contact the Assessor if you have questions) 75TH PL W - - - EDMONDS, WA 98026 Parcel Legal Description Section 05 Township 27 Range 04 Quarter NW LUNDS MEADOWDALE TRS BLK 000 D-01 TH PTN LOT 1 LY E OF E LN EXST CO RD TGW TH PTN VAC 73RD AVE W AS VAC UND CITY OF ED ORD NO 3201 REC UND AFN 9806030195 Go to top of page Treasurer's Tax Information Taxes For answers to questions about Taxes, please contact the Treasurer's office (opens as new window) 2006 Taxes for this parcel $2,684.12 (Taxes may include Surface Water Management and/or State Forest Fire Patrol fees. LID charges, if any, are not included.) To obtain a duplicate tax statement, either download our Tax Statement Request form or call 425-388-3366 to request it by phone. Go to top of page Assessor's Property Data Characteristics and Value Data below are for 2006 tax year. Please contact the Treasurer's office for answers to questions about Taxes (opens as new window) For questions ONLY about property characteristics or property values (NOT taxes), please contact the Assessor's Office (opens as new window) Property Values Values do not reflect adjustments made due to an exemption, such as a senior or disabled persons exemption. Reductions for exemptions are made on the property tax bill. Tax Year 2007 Market Land $380,000 Market Improvement $01 Market Total $380,000 Go to top of page http://web5.co.snohomish.wa.us/propsys/Asr-Tr-Propinq/PrpIngO2-ParcelData.asp?PN=00500900000101 1/15/2007 Snohomish County, WA Assessor Parcel Data Page 2 of 2 Property Characteristics Tax Code Area (TCA) 00217 View Taxing Districts for this Parcel (opens as new window) Use Code 910 Undeveloped (Vacant) Land Size Basis ACRE Size 0.38 (Size may include undivided interest in common tracts and road parcels) perty Structures ,No structures found for this parcel Go to top of page Property Sales since 7/31/1999 Explanation of Sales Information (opens as new window) ISales data is based solely upon excise affidavits processed by the Assessor. Transfer Receipt Sales Excise Deed Grantor (Seller) Grantee (Buyer) Othe Date Date Price Number Type Parce ,10/12/2004 10/13/2004 $125,000 189815 W MAXUM DAVID HILLIARD RONNIE G & SUSAN A No 9/13/2001 1/9/2002 $0 168144 QC MAXUM MARY MAXUM DAVID No 6/22/2000 6/28/2000 $99,950 456990 CHYNOWETH VICTOR & NANCY MAXUM DAVID No 6/22/2000 6/28/2000 $99,950 456990 W CHYNOWETH VICTOR & NANCY DAVID & MARY MAXUM No r Is o to top of page Property Maps Township/Range/Section/Quarter, links to maps Neighborhood 1504000 Explanation of Neighborhood Code (opens as new window) Township 27 Range 04 Section 05 Quarter NW Find parcel maps for this Township/Range/Section View Map of this parcel (opens as new window) F` C�3 ■ I �z�� -' i23r✓ �� I I http://web5.co.snohomish.wa.us/propsys/Asr-Tr-PropInq/PrpIngO2-ParcelData. asp?PN=00500900000101 1/15/2007 1 E C L L a I I 11 r LA 1. Site Vicinity Aerial Photos 8 J.C.McDonnell &Associates 11 I 1 �1 I 1 F 0 L_J F^ 6 r€ ti VICINITY MAP s 0 E 0 t : .' �;. -•--._-,.°-� Beath Rs! .- 6001t y. -ry �, Fisher Rd' ~ t 150th PI Sw -- ListlS�st'S,.l f 3 G(j, Jta 1� L( .1�,9 L� •.+... 77 "'.tF"^4'^'�' ...Y -. ;t f . _ mot.• 4� r' r 75tn� pt w -. 1 }t1� tq� ,t t t' J.� • � e& 1 :.. sr . �, + i '. t t: s {r . � se wE#i t f a�� }t-,��`t��g Ita�",P ,t�,Puyet`5ounrl Y -rt,. , � e ..:r..�.i. t` ',......_.L..:...»a. •' x, i�%��9d9!'Yt�Al2 :.� i t °�� M* tx` County Park � 'tE'i 156ths3 `< r ,{ 157tU, St Sw v i Ti: 14 ! i I+�LP eadov�dale �;,p�► St Sw� /D _ LMeatlowdale �( r �.i i ° t+�+ y'" si � � P fit i 16 nd PI Sw =007NAV'TEQ S.G. MCDONNeLL ENGINEERING PC Consulting Civil Engineers (AP06- 210 Street SW Wuntlat a Terrace, WA. 16043 (425) T14-ogtco (TeL) (425) 714—og4lo (FAX) e-mail: jcmc4on?-@verizon.net Ron Hilliard 6608 — 216th Street SW Mountlake Terrace, WA. 98043 SCALE: None DATE: SHEET: I OF 6 BY. JOB NUMBER: FILE NAME: Photobase I g � G.s t ' ��IL jt rr' f ii R Gf _ - �4'^i.0 v✓ s .y.%•r ��, .i! sr ''�r,r t sr�f SCALE: None DATE: 4.,MTRWIM tg tip 01 5,5 All lots I NO any A _ "2007/01/15 . E R� k.. � � ;k►�i I{��j�;� its 3�� a ��s"�� `�.� � � i� .. t ( i , i Sit °fit DATE: 0 2. Aerial Topography Map 1 11 1 ' 9 J.C.McDonnell &Associates 1 n 0 j L II Ll AERIAL TOPOGRAPHY I S.G. MGDONNELL ENGINEERIN(A VG Consulting Civil Engineers (0606- 2ltpth Street SW Mountlaft Terrace, WK 98o43 (425) TA-o% (TU) (425) T14-094(0 TM) E-mail: jcmcdon2ftorizon.net Ron Hilliard 6608 — 216" Street SW Mountlake Terrace, WA. 98043 SCALE: None DATE: SHEET: 3 OF 6 JOB NUMBER: FILE NAME: BY: I Photobase 6 IJ 3. Edmonds Drainage Exhibit 1� 11 E E u ' 10 J.C.McDonnell &Associates 11 11 li 1 C� w J W W `� O I J w ,�v W V W �1 A z O LU w mE CL W x a E-4 m ao m c z J Q O 0 w a zo ►��,, w J �1 a a z O z M q urir E-4 w � w 7 N ui = ww w xo CL N �a � z LL0 w gU aQ } �jw UUco m U J z PIz z W a O z JO U a0 kv 4 Q U� W= dz ~ z F� o �— --� U �WO L(U) O w ►J- z w Tw QU Z IC 1 w z Q m �II U FEZ U � J O1 F- z O U U 0 F- z 02 w O O `\LL J \ JQ a m Wz U o 0 Xa_ �4 U iv Z 0 Qc m U Q U w a IL z O w x r z w d' w a m W J O Q a cr c 0 Zo O z w a0 o Q Y a 0 0� a ko �. w -R,,,� J 2 � L OWL ID UZ ao p to v Z Z r_ O —_ 05 o � z, .0 a> On.Ww 2x ma- N mn N Q = N Z 7 �¢-0 Ea F�Z o aR c QY ai o 0 Q C w a m a� �m LF Z� Ec.a U)LL c.3 w >moE wa) U 0 Z F- 0 0 ww ° @ o m Zz,E�o C9Za o Z2 W22 wW aa) o �VJ tpc 0 Q} 01 3L Utn� of- N. I Table 1 -- Detention Pipe Sizes ' * Impervious Surface Required Pipe Diameter Area Sq. Ft. Vol Cu Ft 15' 18" 24" 30" ' 2000 50 40 28 16 10 13 2500 62 50 35 20 3000 75 60 42 24 15 Required pipe 3� 3500 87 _ 55; a 70 49 28 18 length in feet `4000 100 80 56 32 21 4500 112 90 63 36 23 5000 125 100 70 40 25 ' *NOTE: Use the next highest surface area to determine detention size if calculated impervious surface area is greater than 1/2 the value between numbers. (i.e., 2280 use 2500) I r Table 2 -- Outlet Orifice Sizes ' Impervious Surface Area Sq. Ft. Outlet Orifice Diameter (Inches) 2000-2999 5/8 3000-3999 3/4 �-- � L-F ' i`" PL-)6- • � ti � ` 4000-5000 7/8 Table 3 -- Rectangular Catch Basin Requirements ' Detention Max. Size Catch Basin. pipe diameter knockout Type < 18" 20" Type I, CB 15 18" to 24" 26" Type IL, CB 16 24" to 36" 36" Type II, CB 19 19 (48" Basin) t36" to 42" 42" Type II, CB 19 19 (54" Basin) *Source: Assoc. Sand & Gravel Co. Standards ' ALLLOWABLE STORM DRAINAGE DETENTION OR CONVEYANCE MATERIALS: ' • Reinforced Concrete (right-of-way) • Non -reinforced Concrete (non -right-of-way) • Aluminized Steel • Aluminum 16 GA or better ' • CMP Asphalt Coated • N-12 ADS HDPE (Min. 2' cover required under paved areas) water tight ' • PVC-SDR 35, ASTMD-3034 or better • Ribbed PVC pipe, ASTM D-2444 • Ducticle iron pipe Class 50 ' - Tightlines system: • N-12 ADS (Smooth Wall) • PVC-SDR 35, ASTMD-3034, or better ' • Hancor F-810 ' S:\ENGR\HANDOUTS\Drainage tables E21 11 1 1 11 SOIL SURVEY OF . SNOHOMISH COUI` L 3/4 1/2 1/4 0 1 0.5 0 7 1 l I 1 .1 I i 4. Geotechnical Report - Soil Data 11 J.C.McDonnell & Associates � Cornerstone 19 Geotechnical, Inc. January 22, 2007 Mr. Ron Hilliard 6608 — 216" Street SW, Suite 304 Mountlake Terrace, Washington 98043 Geotechnical Engineering Report Proposed Single -Family Residence 156`' Street Southwest and 75`h Place West Parcel No. 00500900000101 Edmonds, Washington CG File No. 2212 IDear Mr. Hilliard: 17625-130"h Ave. NE, C102, Woodinville, WA 98072 Phone: 425.844-1977 Fax: 425.844.1987 INTRODUCTION This report presents the results of our geotechnical engineering investigation for the proposed residential project in Edmonds, Washington. The site is located within the Meadowdale slide area, northeast of the intersection of 75h Place West and the easement for 1566' Street Southwest, as shown on the Vicinity Map in Figure 1. The Meadowdale slide area is located approximately between 165'' Street Southwest and Meadowdale Beach County Park in the north -south direction, and Puget Sound and 68`h Avenue West in the east -west direction. This feature is approximately 3,000 feet long and 500 to 800 feet wide. At your request, we have completed this report to evaluate the subsurface conditions at the property and provide recommendations for site development and risks associated with development within a landslide area. We have received a site plan showing the slope area and planned house layout, as well as the City. of Edmonds' Earth Subsidence Landslide Hazard Area (ESLHA) packet. The ESLHA packet includes information, requirements, and regulations concerning construction within the Meadowdale landslide area in the City of Edmonds. PROJECT DESCRIPTION The property includes a steep slope area with magnitudes greater than 100 percent, as well as a nearly level portion that slopes down toward 75`' Place West. The current development plan indicates that a IGeotechnical Engineering Report Proposed Single Family Residence Edmonds, Washington January 22, 2007 CG File No. 2212 Page 2 two-story wood -framed structure with a partial daylight basement will be constructed. A driveway will extend from 75'' Place West onto the property west of the proposed residence. Portions of the basement level will not be fully excavated, leaving areas with crawlspace in the northeast portion of the residence. rWe expect cuts of 6 to 8 feet for portions of the basement level. The northeast corner of the structure will extend into the steep slope. We have discussed the potential of debris flows from the steep slope area. The structure will need to be designed for this loading condition, or a separate debris wall will have to be constructed. We understand that the northeast corner of the ' residence will be designed to accommodate the loads, but as the structure is located away from the slope to the south, a debris wall will need to be constructed. SCOPE The purpose of this study is to explore and characterize the subsurface conditions and present recommendations for site development. Specifically, our scope of services as outlined in our Services Agreement, dated July 11, 2005, includes the following: 1. Review of soils and geologic maps of the area, including the ordinances specific to the Meadowdale area. 2. Evaluate subsurface soil and. ground waterconditions at the site with a subcontracted backhoe. - \ 3. Provide an evaluation of the steep slope portion of the site and recommendations for mitigating the risk posed to the proposed residence by this slope. 4. Provide recommendations for building foundations. 5. Provide recommendations for site preparation and grading 6. Provide general surface drainage recommendations. 7. Meet with you and your designer to discuss site constraints on the project. 8. Prepare a written report to document our findings and recommendations. 1 1 Cornerstone Geotechnical, Inc. Geotechnical Engineering Report Proposed Single Family Residence Edmonds, Washington January 22, 2007 CG File No. 2212 Page 3 SITE CONDITIONS Surface Conditions The site consists of one parcel with an area of approximately 0.38 acres, with a north -south length of �j approximately 100 feet and an east -west length of approximately 165 feet. The property is bordered to the west by 75`h Place West, to the east and south by residential structures, and to the north by an undeveloped lot. A layout of the site is shown on the Site Plan in Figure 2. The topographic map indicates that the eastern three-quarters of the site slopes downward to the west and southwest at inclinations of 100 to 115 percent, with a site elevation change of approximately 75 to 85 feet. We estimate that the slope continues off -site another 20 feet. This slope area is vegetated with blackberry, grasses, and vine maple, as well as sparse maple, alder, and fir trees. The largest trees have been located by surveying, and are shown on the Site Plan. A debris slide occurred within the last 20 years just south of the site, along the easement for 156d' Street Southwest. At this time, this area is vegetated with brush and a new above -ground storm line is in place extending down the slope. The area of the proposed structure slopes gently downward to the west and southwest at inclinations of 10 to 15 percent, with an overall elevation change of about 6 feet, and is vegetated with blackberry and grasses. The western margin of the site slopes down to 75`h Place West at an inclination of approximately 75 percent, with an overall elevation change of 10 feet. That slope is vegetated with brush and grasses. Geology Most of the Puget Sound region was affected by past intrusion of continental glaciation. The last period of glaciation, the Vashon Stade of the Fraser Glaciation, ended approximately 11,000 years ago. Prior to the Fraser Glaciation, non -glacial sediments, including interbedded mixtures and layers of sand, silt, clay, and gravel were deposited and together with older glacial deposits, were subsequently eroded by the most recent glaciation. The Preliminary Surficial Geologic Map of the Edmonds East and Edmonds West Quadrangles, by Mackey Smith, dated 1975, was reviewed for this site. The site is shown to be located in an area where pre-Vashon geologic units of the Whidbey and Double Bluff Formations exist. Vashon Advance outwash and glacial till are mapped at.higher elevations. Specifically, this site is mapped as being within a large landslide feature. i Cornerstone Geotechnical, Inc. A t r A t 1 Geotechnical Engineering Report Proposed.Single Family Residence Edmonds, Washington January 22, 2007 CG File No. 2212 Page 4 The landslide has been the subject of previous geotechnical studies by Roger Lowe and Associates and GeoEngineers, Inc. These studies provided evaluations of the slide and recommendations to increase the stability of the slide mass. The most significant. recommendations for increasing the stability was the installation of drains within and adjacent to the slide mass. The Roger Lowe report included a map of the landslide where specific hazards were mapped, with an estimate of the probability of reoccurrence. The GeoEngineers report modified that map to reflect decreased reoccurrence probabilities based on the drainage improvements. We understand that these probabilities were derived from a qualitative assessment -based on historical movements. They were not based on rigorous probability analysis. Our subsurface explorations encountered stiff to hard silt within the steep slope areas, consistent with pre- Vashon sediments, and a loose to medium dense_mixture of sand, silt, and gravel in the western quarter of the site, consistent with colluvium or landslide debris derived from the outwash and till deposits, found upslope of the site. Explorations Subsurface conditions were explored at the site on October 25, 2006, by excavating four test pits. with a subcontracted backhoe. The test pits ranged in depth from 13.0 to 15.5 feet below the ground surface. The explorations were located and logged in the field by a geologist from this firm who also examined the soils and geologic conditions encountered. The site and. test pit conditions were also observed by Dr. Donald W. Tubbs, LEG, a sub -consultant engineering geologist we have retained for this project. The approximate locations of the test pits are shown on the Site Plan in Figure 2. Cross -sections, showing the subsurface soils and topography in profile, are presented in Figures 3 and 4. The soils were visually classified in general accordance with the Unified Soil Classification System, a copy of which is presented as Figure 5. The logs of the test pits are presented in Figures 6 and 7. Subsurface Conditions A brief description of the conditions encountered in our explorations is included below. A more detailed description of the soils encountered can be found in the test pit logs in Figures 6 and 7. Test Pit 1 encountered loose to medium dense, silty fine to medium grained sand with variable amounts of gravel and organic debris, indicative of landslide debris, down to the termination depth of Test Pit 1. Test Pits 2 and 3 encountered 3.0 to 5.0 feet of loose to medium dense fill, consisting of silty fine sand 11 Cornerstone Geotechnical, Inc. 1 1 r Geotechnical Engineering Report Proposed Single Family Residence Edmonds, Washington January 22, 2007 CG File No. 2212 Page 5 with variable amounts of gravel, underlain by a 1.0 to 1.5 foot -thick layer of buried topsoil. The topsoil layer is loose to medium dense and includes wood debris up to 18 inches in diameter. Below the topsoil is a medium dense/stiff mixture of sandy silt and silty fine sand with variable amounts of gravel, indicative of landslide debris, down to the termination depth of Test Pits 2 and 3. Test Pit 4 was located about 8 feet north of Test Pit 1, in the face of the steep slope, and encountered 8.5 feet of stiff to hard silt, consistent with pre-Vashon sediments. An apparent shear zone with a dip of approximately 60 degrees, and a thickness of 18 inches was observed in the test pit, southwest of the hard silt. As the test pit was advanced downward and to the southwest, a variable mixture of silt and silty fine - sand with variable amounts of gravel and organic debris was encountered, consistent with landslide deposits, down to the termination depth of Test Pit 4. Hydrologic Conditions Groundwater seepage was not observed in the excavated test pits. If groundwater is encountered during construction, it would most likely be found in pockets, perched on less permeable strata within the landslide debris. Perched water does not represent a regional ground water "table" within the upper soil horizons. Volumes of perched ground water vary depending upon the time of year and the upslope recharge conditions. GEOLOGIC HAZARDS General Meadowdale Landslide Description The Meadowdale landslide complex consists of historic block movements, slumps, and debris slides. This is a large-scale feature, approximately 3,000 feet long and 500 to 800 feet wide. The system includes large rotational slides extending through the underlying silt, with lateral movements within smaller landslide blocks. The blocks are composed of glacial till, outwash, and pre-Vashon silts, and the debris slides are comprised of colluvium. Groundwater collection and diversion systems were installed in the early 1980's, and have helped reduce the likelihood of landslide activity. The Roger Lowe and Associates report discussed the probability of slope movement for a given location in the complex based on the observed topographic and geologic conditions. The follow-up report by GeoEngineers and accompanying map include the previous reports' description and probabilities, along with updated probabilities based on the affect the drainage systems had on the overall groundwater levels Cornerstone Geotechnical, Inc. 1 l� 1 1 Geotechnical Engineering Report Proposed Single Family Residence Edmonds, Washington January 22, 2007 CG File No. 2212 Page 6 in the area. This map indicates that the site is located within an area with `hazards from encroaching landslide materials' and `hazards from ground failure in previously failed material.' The first hazard is from material sloughing off the steep slope in the eastern portion of the property. The second hazard would be from movement of the large blocks within the slide complex, below the steep slope. General Site Landslide Description The site includes two distinct types of landslide -derived topographic regions. The eastern portion of the property consists of an over -steepened slope area that we interpret to be a slide scarp. This slope is generally comprised of pre-Vashon sediments, and covered with 1 to 2 feet of colluvium and vegetation. The western portion of the property is nearly level, and consists of a relatively intact and uniform block of landslide materials, which previously slid into its present location. Slump Block Area The landslide block in the western quarter of the site is comprised of a generally medium dense mixture of silt, sand, gravel, and local organic debris. The soils encountered during our subsurface explorations in this area were consistent in relative density and compositional layering, indicating that the block is relatively intact. Furthermore, we did not observe off -sets, settlement, or slumping; within the site or adjacent street areas. The updated probability map by GeoEngineers, dated July 25, 1984, indicates that the relatively level slumped area has `hazards from ground failure in previously failed material,' with a probability of 10 percent occurrence during a 25-year period. This probability was lowered from 35 .percent following the placement of area drainage systems. Debris Slide Area The steep .slope area extending above the area of the proposed residence is comprised of relatively dense, non -glacial silt overlain by glacial outwash and till. We consider these soils to be of moderate to high strength. . We conducted a reconnaissance and limited evaluation of the steep area with Dr. Donald W. Tubbs, LEG, of Tubbs Geosciences. During our evaluation, we did not observe any evidence of recentlactive sloughing of the slope area within the site. However, a relatively recent slide occurred south of the Cornerstone Geotechnical, Inc. Geotechnical Engineering Report Proposed Single Family Residence Edmonds, Washington January 22, 2007 CG File No. 2212 Page 7 property, where a new storm line has since been placed. The slide was a shallow slough event, less than 2 feet in thickness. We understand that this failure was also tied to the construction, and/or draining of a swimming pool. located above the top of the slope. Groundwater located at the contact between the .pre- �' Vashon .sediments and overlying advance outwash, can raise the probability that these slough events will occur. We did not observe evidence of springs or seeps on the steep slope area where the contact between those units was identified. We conducted periodic probing of the soils on the steep slope area above the location of the proposed residence, and found 0.5 to 1.5 feet of relatively loose colluvium overlying dense materials. Any slough events would likely occur along the contact between the colluvium and underlying material, and are expected to be surficial in nature. This is consistent with the slough failure described above. These types of events are affected.by surface water, man-made impacts, and seismic activity. The risk of sloughing can be minimized if proper drainage is installed, vegetation on the slope is maintained, and yard waste and other debris are kept off the slopes. We would expect if a slough event were to occur, it would be. very shallow, approximately 1.25 feet in thickness. The updated probability map by GeoEngineers, dated July 25, 1984, indicates that the steep slope area has ` from encroaching landslide. materials,' with a probability of 2 percent occurrence during a 25- hazards g � year period. It is our opinion, based on the recent surface slide south of the site and the thickness of colluvium on the slope, e that the probability of surficial movement is greater than 2 percent. We have recommended the construction of a retaining wall northeast and east of the residence, and/or incorporated into the residential structure. These walls provide catchment of debris derived from failures on the slope above. At this time, there are six trees on the steep slope area that could potentially damage the structure, if they 1 were to fall, and/or be part of a debris slide. The locations of these trees have been surveyed by you, and are shown on the Site Plan in Figure 2. Most of the trees on the slope area have been topped in the last 20 years, and show signs of past cutting as well. We recommend that dead and leaning trees, as well as the trees with a base diameter greater than 18 inches, be cut and removed, leaving the root systems intact and in -place. The larger diameter trees would be considered projectiles if a sloughing event occurred, and pose a risk to life and structure. It is typically not feasible to design a retaining wall system to stop high point -load debris, such as trees, from hitting the residence. A debris catchment or netting system can be i Cornerstone Geotechnical, Inc. J E 1 1 1 1 I Geotechnical Engineering Report Proposed Single Family Residence Edmonds, Washington January 22, 2007 CG File No. 2212 Page 8 used to reduce impact on the catchment wall. We can provide details regarding these types of systems upon request. Seismic Hazard It is our opinion, based on our subsurface explorations, that the Soil Profile in accordance with Table 1615.1.1 of the 2003 International Building Code (IBC) is Soil Class D. We referenced the 2002 map from the US Geological Survey (USGS) website to obtain values for .Sg and, S,. The USGS website includes the most updated published data on seismic conditions. The seismic design parameters are: S$ 123.84% g S1 43.51% g Fa 1.0 From Table 1615.1.2(1) of the 2003 IBC F„ 1.56 From Table 1615.1.2(2) of the 2003 IBC Site specific coefficients and adjusted maximum considered earthquake spectral response acceleration parameters apply as shown in Section 1615.1 of the IBC. Additional seismic considerations include liquefaction potential and amplification of ground motions by soft soil deposits. The liquefaction potential is highest for loose sand with a high ground water table. The fine-grained, generally medium dense soils interpreted to underlie the site are considered to have a low potential for liquefaction and amplification of ground motion. Seismic. activity can reactivate previously slid materials, causing debris flows and large, deep-seated failures. The impact that a seismic event would have on the deep seated slide complex underlying this site is unknown. However, we recommend in this report that debris catchment walls be designed for debris flow materials that could occur during seismic events. CONCLUSIONS AND RECOMMENDATIONS General The underlying slide block and old colluvium appear sufficiently dense and capable of foundation support. However, due to the potential varying conditions in this type of deposit, we recommend that the Cornerstone Geotechnical, Inc. Geotechnical Engineering Report Proposed Single Family Residence Edmonds, Washington January 22, 2007 CG File No. 2212 Page 9 proposed residence be constructed with a stiffened foundation system and at least 2 feet of structural fill beneath the footings. A retaining wall debris catchment system should be constructed to protect the residence from debris flows originating up slope. It is our opinion that the block of material on which the residence will be constructed is relatively uniform and intact. The overexcavation and stiffened foundation system will limit the potential for differential settlement and structural distress. The retaining walls north and east of the residence will collect debris that slides from the upper slope area. A portion of the wall can be incorporated into the design of the residence. The adjacent walls should consist of cast - in -place concrete or soldier piles with lagging. We have included recommendations for each type of system. We recommend removal of the three dead and/or leaningtrees and the three trees eater than 18 inches �' in diameter, located northeast and east of the proposed residence. These trees have a potential to damage . the proposed structure and pose a risk to life and property. These trees are shown on the Site Plan in Figure 2. If constructed as proposed, and following these recommendations, the construction of the. proposed residence should not negatively impact or affect adjacent, neighboring properties. Furthermore, the placement and construction of the retaining wall systems should not affect underground public utilities, and it is our opinion that special measures for their protection are necessary. Cornerstone Geotechnical should observe all grading and excavation activities, including footing excavations, fill placement, and retaining wall construction. Site Preparations and Grading Site preparation should begin with the removal of vegetation, topsoil, and any loose material within the building areas. The excavated material should be removed from the site, or stockpiled for later use as 1 landscaping fill. The resulting subgrade should be compacted to a firm, non:yielding condition. Areas observed to pump or weave should be repaired prior to placing hard surfaces. The large -diameter trees should be removed as discussed above, leaving their root systems in -place. Following this procedure, the retaining wall system should be constructed along the base of the steep slope area. Cornerstone Geotechnical, Inc. i 1 1 1 1 L� J, Geotechnical Engineering Report Proposed Single Family Residence Edmonds, Washington January 22, 2007 CG File No. 2212 Page 10 Most of the on -site soils likely to be exposed during construction are considered moisture sensitive, and the surface will disturb easily when wet. We expect that these soils will be difficult, to compact to structural fill specifications in wet weather. We recommend that earthwork be conducted during the drier months. Additional expenses of wet weather or winter construction could include over -excavation and the use of imported fill or rock "spalls. During wet weather, alternative site preparation methods may be necessary. These methods may include utilizing a smooth -bucket trackhoe to complete site stripping and diverting construction traffic around prepared subgrades. Disturbance to the prepared subgrade may be minimized by placing a layer of rock spalls or imported sand and gravel in traffic and roadway areas. Structural Fill General: All fill placed beneath buildings, pavements or other settlement sensitive features should be placed as structural fill. Structural fill, by definition, is placed in accordance with prescribed methods and standards, and is monitored by an experienced geotechnical professional or soils technician. Field. observation procedures would include the performance of a representative number of in -place density tests to document the attainment of the desired degree of relative compaction. Materials: Imported structural fill should consist of a free -draining granular soil, free of organics and other deleterious material, and be well graded to a maximum size of approximately 3 inches. Imported all-weather structural fill should contain no more than 5 percent fines (soil finer than a Standard U.S. No. 200 sieve), based on that fraction passing the U.S. 3/4-inch sieve. The use of on -site soil as structural fill should be limited to pavement areas only, and will be dependent on moisture content control. Imported structural fill should be used beneath all footing areas for the proposed structure. Some drying of the native soils may be necessary in order to achieve compaction. During warm, sunny days this could be accomplished by spreading the material in thin lifts and compacting. Some aeration and/or addition of moisture may also be necessary. Compaction of the native soils to structural fill specifications will be more difficult during wet weather. Fill Placement: Upon overexcavation of at least 2 feet of the fill beneath the footing areas, imported structural fill should be placed in 8- to 10-inch-thick uniform lifts, and each lift should be spread evenly and be thoroughly compacted prior to placement of subsequent lifts. All structural fill underlying building areas, and within a depth of 2 feet below pavement and sidewalk subgrade, should be compacted it Cornerstone Geotechnical, Inc. n Geotechnical Engineering Report Proposed Single Family Residence Edmonds, Washington January 22, 2007 CG File No. 2212 Page 11 to at least 95 percent of its maximum dry density. Maximum dry density, in this report, refers to that density as determined by the ASTM D1557 compaction test procedure. Fill more than 2 feet beneath sidewalks and pavement subgrades should be compacted to at least 90 percent of the maximum dry density. The moisture content of the soil to be compacted should be within about 2 percent of optimum so that a readily compactable condition exists. It may be necessary to overexcavate and remove wet surficial soils in cases where drying to -a compactable condition is not feasible. All compaction should be accomplished by equipment of a type and size sufficient to attain the desired degree of compaction. Temporary and Permanent Slopes rTemporary cut slope stability is a function of many factors, such as the type and consistency of soils, depth of the cut, surcharge loads adjacent to the excavation, length of time a cut remains open, and the presence of surface or ground. water. It is difficult under these variable conditions. to estimate stable temporary cut slope geometry. Therefore, it should be the responsibility of the contractor to maintain safe ' slope configurations, since the contractor is continuously at the job site, able to observe the nature and condition of the cut slopes, and. able to monitor the subsurface materials and groundwater conditions encountered. For planning purposes, we recommend that temporary cuts in the fill soils and landslide debris be no steeper than 1.5 Horizontal to 1 Vertical (1.5H:1V). Locally, cuts may stand at a 1H:1V inclination or possibly steeper; however, we should be on -site to make that determination. If ground water seepage is !' encountered, we would expect that flatter inclinations would be necessary. We do not expect temporary cuts greater than 8-feet tall, or permanent slope configurations steeper than a 2H:1 V. We recommend that cut slopes be protected from erosion. Measures taken may include covering cut slopes with plastic sheeting and diverting surface runoff away from the top of cut slopes. We do not recommend vertical slopes for cuts deeper than 4 feet, if worker access is necessary. We recommend that cut slope heights and inclinations conform to local and WISHA/OSHA standards. Foundations The on -site colluvium and landslide materials may have inconsistent densities by nature of the deposit. We recommend that foundations be founded on 2 feet of compacted structural fill, and that the foundations be suitably reinforces to allow a foundation span of 10 feet. These measures will reduce the Cornerstone Geotechnical, Inc. �J I 1 1 Geotechnical Engineering Report Proposed Single Family Residence Edmonds, Washington January 22, 2007 CG File No. 2212 Page 12 impact of potential differential settlement of the structure. The structural fill should extend a minimum of 2 feet beyond the edges of the footings in order to create a 111:1V. envelope from the base of the footings to the medium dense native soils. Minimum foundation widths should conform to IBC requirements. Standing water should not be allowed to accumulate in footing trenches. All loose or disturbed soil should be removed from the foundation excavation prior to placing concrete. For foundations constructed as outlined above, we recommend an allowable design bearing pressure of 1,500 pounds per square foot (psf) be used for the footing design. IBC guidelines should be followed when considering short-term transitory wind or seismic loads. The foundations should be reinforced to span 10 feet unsupported to resist potential differentialsettlement. Standard Retaining Walls The following recommendations are for concrete retaining walls located away from the base of the steep slope area. Subsequent sections provide recommendations for Debris Walls and Soldier Pile Walls; which will be placed along the base of the slope area. The lateral earth pressure acting on retaining walls is dependent on the nature and density of the soil behind the wall, the amount of lateral wall movement; which can occur as backfill is placed, and the inclination of the backfill. Walls that are free to yield at least one -thousandth of the height of the wall are in an "active" condition. Walls restrained from movement by stiffness or bracing are in an "at -rest" condition. Active earth pressure and at -rest earth pressure can be calculated based on equivalent fluid density. Equivalent fluid densities for active and at -rest earth pressure of 40 pounds per cubic foot (pcf) and 60 pcf, respectively, may be used for design for a level backslope. These values assume that the on - site soils or imported granular fill are used for backfill, and that the wall backfill is drained. The . preceding values do not include the effects of surcharges, such as due to foundation loads or other surface loads. Surcharge effects should be considered where appropriate. The above drained active and at -rest values should be increased by a uniform pressure of 5.711 and 15.OH psf, respectively, when considering seismic conditions. H represents the wall height. The above lateral pressures may be resisted by friction at the base of the wall and passive resistance against the foundation. A coefficient of friction of 0.40 may be. used to determine the base friction in the native soils. An equivalent fluid density of 175 pcf may be used for passive resistance design. To Cornerstone Geotechnical, Inc. Geotechnical Engineering Report Proposed Single Family Residence Edmonds, Washington January 22, 2007 CG File No. 2212 Page 13 achieve this value of passive pressure, the foundations should be poured "neat" against the native dense soils, or compacted fill should be used as backfill against the front of the footing, and the soil in front of the wall should extend a horizontal distance at least equal to three times the foundation depth. A factor of safety of 2.0 has been applied to the passive pressure to account for required movements to generate these pressures. The friction coefficient does not include a factor of safety. All wall backfill should be well compacted. Care should be taken to prevent the buildup of excess lateral soil pressures due to overcompaction of the wall backfill. Debris Walls The retaining wall incorporated into the single family residence should be designed to support additional material that could slide against it in the event of a shallow debris flow. Additional concrete walls or a ' soldier pile and lagging system should be used along the base of the slope where the residence is located within 30 feet of the slope, or if landscaping protection is desired. Based on our visual assessment and local probing of the colluvium on the face of the steep slope face, we estimate an average depth of 1.25 feet of material that could slide toward the residence. This results in a volume of 3.99 cubic yards per lineal foot of slope, measured across the slope at any given elevation below the elevation of the largest trees. This results in a wall height of 12.5 feet above the base of the adjacent slope area. We have used a 10 degree. backslope in our calculation of height. This height does not include a factor of safety. However, we would expect some deflection sideways along the wall which would reduce the total height. This assumes a large portion of the slope does not move at once. Where the wall can be moved away from the slope 3 feet, this wall height canbe reduced to 8 feet. Where the house is cut into the slope, the corner of the structure forms an apex into the slope. This would help deflect debris reducing the total ' hei t. We consider reducing the 12.5 feet to 10 feet appropriate for this. This could be lowered even more if a slope debris catchment system, as discussed in a subsequent section, is used. Our calculations indicate that debris would flow a horizontal distance of approximately 25 feet from the base of the steep slope area. We recommend construction of a wall system in areas where the proposed residence will be located 30 feet or less from the steep slope. A slope debris catchment system in conjunction with the retaining wall would further reduce the risk of damage to the structure from falling debris. r ' Cornerstone Geotechnical, Inc. 1 r 11 Geotechnical Engineering Report Proposed Single Family Residence Edmonds, Washington January 22, 2007 CG File No. 2212 Page 14 The portion of the retaining wall that will provide catchment for sliding debris should be designed using equivalent fluid densities for active and at -rest earth pressure of 85 pounds per cubic foot (pcf) and 105 pcf, respectively. An equivalent fluid density of 125 pcf may be used for passive resistance design. Soldier Pile Walls Active pressure acting on the piles and lagging for design of soldier piles should be calculated based on a triangular pressure distribution equivalent to that exerted by a fluid with a density of 40 pcf. This pressure acts on the full center -to -center pile spacing above the base of the cut. It has been shown that lagging does not experience the full soil pressure; therefore, 1/2 of the active pressure can be used for the design of the timber lagging. The passive resistance is considered to be a triangular distribution, equivalent to that exerted by a fluid. The maximum passive resistance at the bottom of the pile is the product of the passive resistance coefficient and the depth of the pile below the base of the excavation. The passive resistance. coefficient used for design should be 300 pcf, assuming a level ground surface at the base of the planned excavation. This can be considered to act on 2 effective pile diameters, or the pile spacing, whichever is less, below the base of the cut. No safety factors have been applied to the above passive resistance value. Appropriate safety.factors should be applied in the design of the shoring system. We suggest that a safety factor of 2 be applied to the passive resistance value. The portion of the retaining wall that will provide catchment for sliding debris should be designed using equivalent fluid densities for active and at -rest earth pressure of 85 pounds per cubic foot (pcf) and 105 pcf, respectively. An equivalent fluid density of 300 pcf may be used for passive resistance design. Slope Debris Catchment There are slope catchment systems that can slow or stop debris flows prior to impacting the retaining walls. These systems would add additional safety factor in protection of the structure and also could be used to lower the debris wall heights. We have obtained data on a system produced by Geobrugg. This system essentially anchors a debris catchment net placed over the slope. A debris catchment fence placed on the slope near the base would prevent a majority of material from hitting the house. These systems are typically. expensive, and may not be as cost-effective as retaining wall systems. The cost of these systems should be weighed against the added protection they provide to the residence. We can provide information on these types of systems upon request. E Cornerstone Geotechnical, Inc. L _ Geotechnical Engineering Report ' Proposed Single Family Residence Edmonds, Washington January 22, 2007 CG File No. 2212 Page 15 Slabs -On -Grade Slab -on -grade areas should be prepared as recommended in the Site Preparation and Grading subsection. Slabs should be supported on 1 to 2 feet of structural fill placed on the underlying medium dense silty sands. Where moisture control is a concern, we recommend that slabs be underlain by 6 inches of free -draining coarse sand or pea gravel for use as a capillary break. A suitable vapor barrier, such as heavy plastic sheeting, should be placed over the capillary break. An additional 2-inch-thick damp sand blanket can be used to cover the vapor barrier to protect the membrane and to aid in curing the concrete. This will also help prevent cement paste bleeding down into the capillary break through joints or tears in the vapor barrier. The capillary break material should be connected to the footing drains to provide positive drainage. Erosion and Sediment Control Erosion and sediment control (ESC) is used to minimize the transportation of sediment to wetlands, ' streams, lakes, drainage systems, and adjacent properties. Erosion and sediment control measures should be taken and these measures should be in general accordance with local regulations. At a minimum, the following basic recommendations should be incorporated into the design of the erosion and sediment control features of the site: . 1) Phase the soil, foundation, utility, and other work, requiring excavation or the disturbance of the site soils, to take place during the dry season (generally May through September). However, provided precautions are taken using Best Management Practices (BMP's), grading activities can be undertaken during the wet season (generally October through April). It should be noted that this typically increases the overall project cost. 2) All site work should be completed and stabilized as quickly as possible. 3) Additional perimeter erosion and sediment control features may be required to reduce the possibility of sediment entering. the surface water. This may include additional silt fences, silt fences with a higher Apparent. Opening Size (AOS), construction of a berm, or other filtration systems. 4) Any runoff generated by dewatering discharge should be treated through construction of a ' sediment trap if there is sufficient space. If space is limited, other filtration methods will need to be incorporated. I Cornerstone Geotechnical, Inc. I u 1 1 i' 1 Geotechnical Engineering Report Proposed Single Family Residence Edmonds, Washington January 22, 2007 CG File No. 2212 Page 16 Drainage We recommend that runoff from impervious surfaces, such as roofs, driveway and access roadways, be collected and routed to an appropriate storm water discharge system. We suggest that the finished ground surface be sloped at a gradient of 3 percent minimum for a distance of at least 10 feet away from the buildings, as indicated in IBC Section 1803.3. Surface water should be collected by permanent catch basins and drain lines, and be discharged into a storm drain system. We recommend that footing drains be used around all of the structures where moisture control is important. The underlying silty soils may pond water that could accumulate in crawlspaces. It is good practice to use footing drains installed at least l foot below the planned finished floor slab or crawlspace elevation to provide drainage for the crawlspace. At a minimum, the crawlspaces should be sloped to drain to an outlet tied to the drainage system. We recommend that all drainlines extend away from the steep slope in the east part of the site and connect to a catchbasin south or southwest of the residence. If drains are omitted around slab -on -grade floors where moisture control is important, the slab should be a minimum of 1 foot above surrounding grades. Where used, footing drains should consist of 4-inch-diameter, perforated PVC pipe that is surrounded by free -draining material, such as pea gravel. Footing drains should discharge into tightlines leading to an appropriate collection and discharge point. Crawlspaces should be sloped to drain, and a positive connection should be made into the foundation drainage system. For slabs -on -grade, a drainage path should be provided from the capillary break material to the footing drain system. Roof drains should not be connected to wall or footing drains. IPavement The performance of roadway pavement is critically related to the conditions of the underlying subgrade. We recommend that the subgrade soils within the roadways be treated and prepared as described in the Site Preparation and Grading subsection of this report. Prior to placing base material, the subgrade soils should be compacted to a non -yielding state with a vibratory roller compactor and then proof -rolled with a piece of heavy construction equipment, such as a fully -loaded dump truck. Any. areas with excessive weaving or flexing should be overexcavated and recompacted or replaced with a structural fill or crushed rock placed and compacted in accordance with recommendations provided in the Structural Cornerstone Geotechnical, Inc. I L 1 1 Geotechnical Engineering Report Proposed Single Family Residence Edmonds, Washington January 22, 2007 CG File No. 2212 Page 17 Fill subsection of this report. We would anticipate local overexcavations of up to 3 feet within the proposed driveway areas. CONSTRUCTION OBSERVATION We should be retained to provide observation and consultation services during construction to confirm that the conditions encountered are consistent with those indicated by. the explorations, and to provide recommendations for design changes, should the conditions revealed during the work differ from those anticipated. As part of our services, we would also evaluate whether or not earthwork and foundation installation activities comply with contract plans and specifications. . USE OF THIS REPORT We have prepared this report for Mr. Ron Hilliard and his agents, for use in planning and design of this project. The data and report should be provided to prospective contractors for their bidding and estimating purposes, but our report, conclusions and interpretations should not be construed as a warranty of subsurface conditions. The scope of our services does not include services related to construction safety precautions, and our recommendations are not intended to direct the contractors' methods, techniques, sequences or procedures, except as specifically described in our report, for consideration in design. There are possible variations in subsurface conditions. We recommend that project planning include contingencies in budget and schedule, should areas be found with conditions that vary from those described in this report. Within the limitations of scope, schedule and budget for our services,.we have strived to take care that our services have been completed in accordance with generally accepted practices followed in this area at the time this report was prepared. No other conditions, expressed or implied, should be understood. 000 n Cornerstone Geotechnical, Inc. 1 1 1 1 1 1 1 1 1 1 1 1 i 1 1 1 1 1 Geotechnical Engineering Report Proposed Single Family Residence Edmonds, Washington January 22, 2007 CG File No. 2212 Page 18 We appreciate the opportunity to be of service to you. If there are any questions concerning this report or if we can provide additionalservices, please call. Sincerely, Cornerstone Geotechnical, Inc. /oI washy (756 eased Geo�0 Donald W. Tubbs Donald W. Tubbs, PhD., L.E.G. Consulting Engineer Geologist 107 Charles P. Couvrette, PE Principal Engineer CPC:am Three Copies Submitted Seven Figures Information about this Geotechnical Engineering Report Cornerstone Geotechnical, Inc. 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Vicinity Map t. N G H 'J A 434 435 3 B �- C is Po�Nr 136TH 1 { �' D E F •' ,I t,N �t0 Y 148 Cornerstone Phone: (425) 844-1977 Hilliard Single -Family Residence Fax: (425) 844-1987 Geotechnical, Inc. File Number Figure 17625-130th Ave NE, C-102 - Woodinville, WA - 98072 2212 1 N N � � N a) iz ® +_, Q N Cc v I11 6�� Q N E+ 46 L ~ � J U ca pLD 4 clu. N LU O _ Q Q sl O N U U +r fto ZJ J'S rj) COD ■a z ( I a 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 t 1 ry `N N N • W 1 ' LL '' 1� LZ^, u a 04 N ti ro 4 cct, _ E ti12 1 ' 1 a to a � '1 P 4 �c rn rn C O y CD ® ° . F- N N ° `bay 'D m till ct, o .L ai W i 1 m ,Op C�t a CL c o w ' O h co co V _o I� o IN P U U U U ., lyj Z co cts U � • V • y m coco �.' y as L c� ru O. U) 'AV rV m CO cx i' Q 1 3 EN Co w o Epp pp �qy pp �, Q 1 1 1 1 1 1 1 1 1 1 1 V �IIww v+ NCN o N a cco a •• 3 I c � E z IL Ii y � C yco 4 � V y rn � � • o vO �� a ) 4' O. 9 m - ,O COc avi avi rn • C� o CO c to J ® Qp U U C = LL. •0 2 •. LLI V ' C. m E E a) a� C CD v - co�_� ® a c V �; (L)cu ~ J a c o N r^ CVO O tF4 a `��° ~ 0 v c a �♦U^ 6•s E m . `• t Ev a co X d aCO _ ! 3 ca rN cu w 0 y o.•� •o v a _ r- N N Q p '• S C4 � G & � O �_ 1 L 1 I C�I 1 Unified Soil Classification System MAJOR DIVISIONS GROUP SYMBOL GROUP NAME COARSE - GRAVEL CLEAN GRAVEL GW WELL -GRADED GRAVEL, FINE TO COARSE GRAVEL GP POORLY -GRADED GRAVEL GRAINED MORE THAN 50%OF COARSE FRACTION GRAVEL WITH FINES GM SILTY GRAVEL SOILS RETAINED ON NO.4 SIEVE GC CLAYEY GRAVEL MORE THAN 50% RETAINED ON, number 200 SIEVE SAND CLEAN SAND SW WELL -GRADED SAND, FINE TO COARSE SAND SP POORLY -GRADED SAND MORE THAN 50% OF COARSE FRACTION PASSES NO.4 SIEVE SAND WITH FINES SM SILTY SAND SC CLAYEY SAND FINE - SILT AND CLAY INORGANIC ML SILT CL CLAY GRAINED LIQUID LIMIT LESS THAN 50% SOILS ORGANIC OL ORGANIC SILT, ORGANIC CLAY MORETHAN 50% PASSES NO.200 SIEVE SILTAND CLAY INORGANIC MH SILT OF HIGH PLASTICITY, ELASTIC SILT CH CLAY OF HIGH PLASTICITY, FAT CLAY LIQUID LIMIT 50% OR MORE ORGANIC OH ORGANIC CLAY, ORGANIC SILT HIGHLY ORGANIC SOILS PT PEAT NOTES: SOIL MOISTURE MODIFIERS 1) Field classification is based on Dry -Absence of moisture, dusty, dry visual examination of soil in general to the touch accordance with ASTM D 2488-83. 2) Soil classification using laboratory Moist- Damp, but no visible water tests is based on A8TM D 2487-83. Wet- Visible free water or saturated, 3) Descriptions of soil density or usually soil is obtained from consistency are based on below water table interpretation of blowcount data, visual appearance of soils, and/or test data. Cornerstone Phone: (425) 844-1977 Unified Soil Classification System -` Geotechnical, Inc. Fax: (425) 844-1987 6ME _= 17625.130th Ave NE, C-102 - Woodinville, WA- 98072 Figure 5 ' DEPTH LOG OF EXPLORATION USC SOIL DESCRIPTION ' TEST PIT ONE 0.0-4.0 SM LIGHT BROWN SILTY FINE TO MEDIUM SAND WITH TRACE GRAVEL (LOOSE TO MEDIUM DENSE, DRY) (SLIDE DEBRIS) -INCREASED FINES BELOW 2.0 FEET -ROOTLETS OBSERVED BELOW 2.0 FEET ' 4.0 - 7.0 SM LIGHT BROWN SILTY FINE TO MEDIUM SAND (MEDIUM DENSE, DRY) (SLIDE DEBRIS) -VERY WEAK CEMENTATION OBSERVED AT 4.0 FEET -NO CEMENTATION OBSERVED BELOW 5.0 FEET ' 7.0 - 8.0 SP REDDISH BROWN FINE TO COARSE SAND WITH TRACE GRAVEL (LOOSE TO MEDIUM DENSE, MOIST) (SLIDE DEBRIS) 8.0 - 9.0 SM LIGHT BROWN SILTY FINE TO MEDIUM SAND (LOOSE TO MEDIUM DENSE, ' MOIST) (SLIDE DEBRIS) -TRACE ORGANICS (WOOD DEBRIS) FOUND AT 8.6 FEET 9.0 -10.5 SP REDDISH BROWN FINE TO COARSE SAND WITH TRACE GRAVEL (LOOSE ' TO MEDIUM, MOIST) (SLIDE DEBRIS) 10.5 -13.0 SM LIGHT BROWN SILTY FINE SAND WITH TRACE GRAVEL (LOOSE TO MEDIUM DENSE, MOIST) (SLIDE DEBRIS) SAMPLES WERE COLLECTED AT 2.5, 4.0, 7.0, 8.0, AND 9.5 FEET GROUNDWATER SEEPAGE WAS. NOT ENCOUNTERED TEST PIT CAVING WAS ENCOUNTERED AT 10.5 FEET ' TEST PIT WAS COMPLETED TO 13.0 FEET ON 10-25-06 TEST PIT TWO 0.0 - 3.0 SM LIGHT BROWN SILTY FINE TO MEDIUM SAND WITH TRACE GRAVEL AND ORGANICS (LOOSE TO MEDIUM DENSE; MOIST) (FILL) . -SMALL LAYERS (6 INCHES OR LESS THICKNESS) OF REDDISH BROWN SILTY FINE TO MEDIUM SAND WITH TRACE GRAVEL ' -BURIED ORGANICS (ROOTS, DEBRIS) BELOW SURFACE 3.0 -4.0 SM DARK BROWN SILTY FINE TO MEDIUM SAND WITH ORGANICS (LOOSE TO ' MEDIUM DENSE, MOIST) (BURIED TOPSOIL LAYER) -BURIED TOPSOIL LAYER DIPS APPROXIMATELY 5 DEGREES TO THE NORTH ' 4.0 - 7.0 SM LIGHT BROWN SILTY FINE TO MEDIUM SAND (LOOSE TO MEDIUM DENSE, MOIST) (SLIDE DEBRIS) 7.0 -13.0 ML GRAY, RUST -MOTTLED SANDY SILT WITH TRACE GRAVEL (STIFF TO VERY STIFF, MOIST) (SLIDE DEBRIS) -ORGANICS (ROOTS) OBSERVED AT 8.0 FEET -MOTTLING MORE DISTINCT BELOW 10.0 FEET 13.0 -14.0 SM GRAY RUST MOTTLED SILTY VERY FINE TO FINE SAND (LOOSE TO MEDIUM DENSE, MOIST) (SLIDE DEBRIS) SAMPLES WERE COLLECTED AT 2.5, 7.0, 12.0, AND 14.0 FEET ' GROUNDWATER SEEPAGE WAS NOT OBSERVED TEST PIT CAVING WAS NOT OBSERVED TEST PIT WAS COMPLETED TO 14.0 FEET ON 10-25-06 CORNERSTONE GEOTECHNICAL, INC. FILE NO 2212 FIGURE 6 LOG OF EXPLORATION 1 L L� L-1 DEPTH TEST PIT THREE USC SOIL DESCRIPTION 0.0 - 5.0 SM DARK BROWN TO GRAY SILTY FINE TO MEDIUM SAND WITH GRAVEL (LOOSE TO MEDIUM DENSE, MOIST) (FILL) -ROOTLETS OBSERVED AT 4.0 FEET 5.0 - 6.5 SM DARK BROWN SILTY FINE TO MEDIUM SAND WITH TRACE GRAVEL AND ROOTS (LOOSE TO MEDIUM DENSE, MOIST) (BURIED TOPSOIL LAYER) -BURIED TOPSOIL LAYER DIPS APPROXIMATELY 5 DEGREES TO THE NORTH -ORGANICS (STUMP) FOUND AT 6.0 FEET 6.5 -14.0 SM GRAY RUST MOTTLED SILTY FINE SAND WITH TRACE GRAVEL AND ROOTS (LOOSE TO MEDIUM DENSE) (SLIDE DEBRIS) SAMPLES WERE COLLECTED AT 1.5, 8.0, 12.0, AND 14.0 FEET GROUNDWATER SEEPAGE WAS NOT OBSERVED TEST PIT CAVING WAS NOT OBSERVED TEST PIT WAS COMPLETED TO 14.0 FEET ON 10-25-06 TEST PIT FOUR 0.0 - 8.5 ML LIGHT BROWN FINE SILT (STIFF TO VERY STIFF, DRY) (PRE-FRASER DEPOSITS) - LAMINATION PRESENT ON SCARP SURFACE - BLOCKY TEXTURE OBSERVED - FALLING MATERIAL WAS OBSERVED ABOVE TEST PIT LOCATION 8.5 -10.0 SM LIGHT BROWN SILTY FINE TO MEDIUM SAND WITH ROOTS (LOOSE TO MEDIUM DENSE, MOIST) (BURIED PRE-VASHON DEPOSITS AND SLIDE DEBRIS CONTACT) -CONTACT PLANE DIPS APPROXIMATELY 60 DEGREES TO THE SOUTH 10.0 -15.5 SM LIGHT BROWN TO BROWN SILTY FINE TO MEDIUM SAND WITH TRACE GRAVEL AND ROOTS (LOOSE TO MEDIUM DENSE, MOIST) (SLIDE DEBRIS) SAMPLES WERE NOT COLLECTED GROUNDWATER SEEPAGE WAS NOT OBSERVED TEST PIT CAVING WAS NOT OBSERVED TEST PIT WAS COMPLETED TO 15.5 FEET ON 10-25-06 CORNERSTONE GEOTECHNICAL, INC. FILE NO 2212 FIGURE 7 1 5. Site Grading Quantities 1 1 t 1 12 ' J.C.McDonnell & Associates Site Grading Quantities Report AutoCAD Report Site Volume Table: Unadjusted• Cut Fill Net* tcu.yds tcu.yds tcu.yds method* aaaaaaoaaaaaaaaaaaaa000aaaaaaaaaoaaaaaaaaaaa000aaaaaaaaaaaaaaaaaaaaaaaaa• Site: Preliminary* Stratum: grading quanitities eg fg* 1005 114 890 (C) Grid • 1010 119 891 (C) Composite • • site: Revised FG• Stratum: revised fq eq fq revised* 212 297 84 (F) Grid • 223 303 81 (F) Composite The Autocad Land Development report addresses the Cuts & Fills for this Site including basement excavation and the respective crawl space excavations under portions of the house as well as the surface cuts & fills around the house building wall. The Volume can be broken down as follows: House plus Basement = 2,120 SF Crawl Space Areas: (1) = 372 SF (2) = 390 SF Total = 760 SF Basement Footprint A = 2,120 SF — 760 SF = 1,360 SF Basement Depth = 224` - 214'= 10 feet Basement Volume = 10(1,360 SF) / 27 CF/CY = 503 CY Crawl Space Depth = 2.0 FT Crawl Space Volume = 2 ( 760 SF) /27 = 56.30 CY Foundation Excavation Volume = 559.3 CY Lot Cut Volume = 1005 CY — 559 CY = 445.7 CY Lot Fill Volume = 303 CY 13 J.C.McDonnell & Associates Site Grading Quantities Report AutoCAD Report • Site Volume Table: Unadjusted* Cut ' Fill Net* tcu.yds tcu.yds tcu.yds Method* • Site: Preliminary Stratum: grading quanitities eg fg+ 1005 114 890 (C) Grid • 1010 119 891 (C) Composite • • Site: Revised FG• Stratum: revised fq eq fq revised* 212 297 84 (F) Grid • 223 303 81 (F) Composite The Autocad Land Development report addresses the Cuts & Fills for this Site including basement excavation and the respective crawl space excavations under portions of -the house as well as the surface cuts & fills around the house building wall. The Volume can be broken down as follows: House plus Basement = 2,120 SF Crawl Space Areas: (1) = 372 SF (2) = 390 SF Total = 760 SF Basement Footprint A = 2,120 SF — 760 SF = 1,360 SF Basement Depth = 224` - 214'= 10 feet Basement Volume = 10(1,360 SF) / 27 CF/CY = 503 CY Crawl Space Depth = 2.0 FT Crawl Space Volume = 2 ( 760 SF) /27 = 56.30 CY Foundation Excavation Volume = 559.3 CY Lot Cut Volume = 1005 CY — 559 CY = 445.7 CY Lot Fill Volume = 303 CY 13 J.C.McDonnell & Associates • Site Volume Table: Unadjusted• Cut Fill Net• tcu.yds tcu.yds tcu.yds Method• 'Site: Preliminary• Stratum: grading quanitities eg fg• 1005 114 890 (C) Grid • 1010 119 891 (C) Composite • • Site: Revised FG• Stratum: revised fg eg fg revised• 212 297 84 (F) Grid • ' 223 303 81 (F) Composite Cornerstone JW Geotechnical, Inc. Consulting Geotechnical Engineers & Geologists June 19, 2009 Mr. Ron Hilliard 6608 - 216`s Street SW, Suite 304 Mountlake Terrace, WA 98043 Water Feature Letter Ron Hilliard Residence 15515 - 75 h Place West Edmonds, Washington CG File No. 2212 Building Permit # 2008-0117 Dear Mr. Hilliard: JUL 8 2009 DEVELOP,WAIT SERVIcEs CTR. C17Y OF El)&JONDS This letter documents our observations and recommendations for the water feature installed at your residence project located at 15515 - 751h Place West in Edmonds, Washington. We have been requested by Steve Barnes, your architect to complete this letter in compliance with a request from the City of Edmonds. A water feature has been constructed in the northern region of the site, off the northeast corner of the residential structure. We did not observe installation of the water feature, but have been informed by Steve Barnes, the site architect, of the design and construction. The information provided is that the water feature was constructed with a plastic liner at the base of the feature to prevent water from seeping into the onsite soils. A felt base was also placed below the plastic liner to prevent punctures from subgrade conditions. Any punctures to the water feature plastic liner would be expected from tree branches that fall from the slope above the feature. If this occurs, the puncture should be fixed immediately. STREET FILE 17625 -130m Avenue NE, C102, Woodinville, WA 98072 - Phone: 425-844-1977 - Fax: 425-844-1987 reature Letter i �iard Resi e ,`;Washin V n e eermit # 2008-0117 19, 2009 eCG File No. 2212 Page 2 Based on our observations and discussions with Mr. Barnes, it is our opinion that the water feature will not adversely affect the stability of the sloping conditions at the site. Excess water should not be allowed to enter the subgrade soils from punctures within the base of the pond liner. We trust that this letter meets your needs at this time. If you have any questions or need further clarification, please call. Sincerely, Cornerstone Geotechnical, Inc. Jeff Wale Project Manager 20285 Charles P. Couvrette, PE Principal Three Copies Submitted JRW:CPC cc: City of Edmonds — one copy Mr. Steve Barnes, Cornerstone Architectural Group — one copy Cornerstone Geotechnical, Inc. ^` Cornerstone fto Geotechnical, Inc. Consulting Geotechnical Engineers & Geologists May 14, 2009 Mr. Ron Hilliard 6608 — 216th Street SW, Suite 304 Mountlake Terrace, WA 98043 Revised Wall Drain Installation Letter Ron Hilliard Residence 15515 — 75th Place West Edmonds, Washington CG File No. 2212 Building Permit # 2008-0117 Dear Mr. Hilliard: JUN 3 2009 DEVELOPMENT SERVICES CTR. CITY OF EDMONDS This letter documents our observations of wall back drain installation at your residence project located at 15515 — 75th Place West in Edmonds, Washington. We have been requested by Mr. Steve Barnes, your architect, to complete this letter in compliance with a request from the City of Edmonds. We were on site during excavation for the retaining wall footings as documented in our field reports. The walls were backfilled prior to our next site visit. We did observe that a drainage composite existed against the wall at the top of the backfill. We also observed drainpipe extending from the backfill at the sides of the excavation. The drain pipe was 4 inch perforated pipe with a mesh containing Styrofoam "peanuts" around the pipe. Both of these conditions are documented in project photographs. The project architect, Steve Barnes stated that he had been on site before backfilling and that the drainage system had been properly installed as shown on the plans. A black coating to restrict vapor was also observed to have been painted on the concrete. 17625 —130th Avenue NE, C102, Woodinville, WA 98072 - Phone: 425-844-1977 - Fax: 425-844-1987 ' Revised Wall Drain InstaiRon Letter Ron Hilliard Residence Edmonds, Washington Building Permit # 2008-0117 May 14, 2009 CG File No. 2212 Page 2 We also met with the earthwork contractor onsite while he was preparing to connect roof and yard drains to stormwater vault. The location of the vault has been moved from the southern region. The vault is now connected to the residential structure at the southwest corner. The new location of the vault will allow discharge to an existing catchbasin located at the southwest corner of the site. We were informed by Steve that the new vault has the same stormwater collection volume as the vault observed in plans. Footing drains are planned to outfall at the northwest and southwest corners of the site to rock outfalls. The rock outfalls will be created during final landscaping. We observed a footing drain pipe daylight near the southwest region. The footing drain at the northwest corner was attached to the wall drain in this area and daylights north of the block retaining wall at the base of the wall. Seepage was not observed during excavations for foundation and soils appeared to be dry to moist. We therefore expect minimal water will be collected from the footing drain. It is our opinion that the footing drain outfalls are adequate because of the minimal water expected to be collected. Based on our observations and discussions with Mr. Barnes, it is our opinion that the wall drainage systems have been properly installed. The roof drains connections to the vault and footing drain outfalls are expected to be completed soon. M•. Cornerstone Geotechnical, Inc. Revised Wall Drain Instaton Letter • Ron Hilliard Residence Edmonds, Washington Building Permit # 2008-0117 May 14, 2009 CG File No. 2212 Page 3 We trust that this letter meets your needs at this time. If you have any questions or need further clarification, please call. Sincerely, Cornerstone Geotechnical, Inc. Jeff Wale Project Manager C U� 5 P. O P OA TF zazas NAL 'G Charles P. Couvrette, PE Principal Three Copies Submitted JRW:CPC:am cc: City of Edmonds — one copy Mr. Steve Barnes, Cornerstone Architectural Group — one copy Cornerstone Geotechnical, Inc. e D Sk 0- REVISED PLAN APP`D ROVED CITY OF EDMONDS �UI�'�s'� a' DIVISION PLANS EXAMMER SEE DETAIL 1/S1 A ��—J •- v __ FOR NOTES #5 0 9" O.C. VERT W/ ALT. — STD 90' HOOK — EXTEND A MINIMUM OF 2'-6" ABOVE F.F. #5 © 15" O.C. HORZ CONT. 0 BOT. A- STREET FILE /wv'X. c ' .0I ",4S m,qk 2" MIN. AIR SPACE VENTED BLOCKING - CEDAR FASCIA EXT. SOFFIT EXTERIOR FRAME WALL CONCR EXISTING FOUNDATION DRAIN - FOUNDATION ALL ROC R-30 BATT WOC INSUL. GWB CEILING GWB OVER VAPOR BARRIER MASTER BED FLOOR CONST. GWB CEILI KITCHEN FUR ED WALL FLOOR SLAB FL( R-10 RIGID INSUL. MEMBRANE WATERPROOFING OVER 0/, FOUNDATION WALL 0 AU6 2 9 2008 BUILDING DEPT, A la 8[ uraC T W V Y ESN/ BUILDING DEPT. Title : Hilliard Residence Job # 07048 Dsgnr: AKE Date: 5:07PM. 7 AUG 08 Description : Scope : Code Ref. ACi 318-02,1997 UBC, 2003 IBC, 2003 NFPA 5000 Kev: aw014. Page 1 User KW-0601622.Ver5.8.0,1-0ec•2o03 Restrained Retaining 9 Wall Design (c)1983.2003 ENERCALC Englneering Software 07048.ecw:Celcutetlons Description Crawl Space B w/ Slide - Dec07 criteria Soil Data Retained Height = 6.00 ft Wall height above so![ = 4.25 ft Total Wall Height = 10.25ft Top Support Height = 10.00 ft Slope Behind Wall = 10.00 : 1 Height of Soil over Toe = 6.00 In Soil Density = 110.00 pcf Allow Soil Bearing = 1,500.0 psf Equivalent Fluid Pressure Method Heel Active Pressure = 60.0 Toe Active Pressure = 0.0 Passive Pressure = 175.0 FootingllSoll Friction = 0.400 Soil height to ignore for passive pressure = 0.00 in Footing Strengths & Dimensions fc = 3,000 psi Fy = 60,000 psi Min. As % = 0.0014 Toe Width - 1.50 it Heel Width - 2.20 Total Footing Width Footing Thickness - 13.00 in Key Width = 8.00 in Key Depth = 0.00 In Key Distance from Toe = 0.00 ft Cover @ To = 3 00 in @ Btm = 3 QO in Wind on Stem = 120.0 psf p Surcharge Loads Uniform Lateral Load Applied to Stem Adjacent Footing Load Surcharge Over Heel = 0.0 psf Lateral Load = 0.0 #/ft Adjacent Footing Load = 0.0 Ibs >>>NOT Used To Resist Sliding & Overtum ,,.Height to Top = 0.00 ft Footing Width - 0.00 ft Surcharge Over Toe = 0.0 psf ...Height to Bottom = 0.06 ft Eccentricity, - 0.00 in NOT Used for Sliding & Overturning Wall to Fig CL Dist = 0.00 It Axial Load Applied to Stem Footing Type Line Base Above/Below Soil = 0.0 ft Axial Dead Load = 400.0 Ibs at Back of Wall Axial Live Load = 500.0 fbs Abal Load Eccentricity = 0.0 in Desi n Summary Concrete Stem. Construction Total Bearing Load = 3,567 Ibs Thickness = 8.00In Fy = 60,000psl ...resultant ecc. = 3.28 in Wall Weight = 96.7 pcf fc = 3,000 psi So II P sure oe Soil Pressure @ Heel = 1,391 psf OK Allowable = 1,500 psf Soil Pressure Less Than Allowable ACI Factored @ Toe = 774 psf ACI Factored @ Heel = 2,006 psf Footing Shear @ Toe = 9.5 psi OK Footing Shear @ Heel = 15.6 psi OK Allowable = 93.1 psi Reaction at Top = 630.4 Ibs Reaction at Bottom = 1,384.8 Ibs Sliding Calcs Slab Resists All Sliding9 I Lateral Sliding Force = 1,384.8lbs Footin Design Results Sliding Calcs Slab Resists All Sliding9 I Lateral Sliding Force = 1,384.8lbs Footin Design Results Factored Pressure oe eel psf Mu': Upward = 1,058 0 ft_# Mu': Downward = 343 1,372 ft- # Mu: Design = 716 1,372 ft- # Actual 1-Way Shear = 9.47 15.65 psi Allow 1-Way Shear = 93.11 93.11 psi Design height Rebar Size Rebar Spacing Rebar Placed at Rebar Depth 'd' Design Data fb/FB + fa/Fa Mu .... Actual Mn " Phi..... Allowable Shear Force @ this height Shear..... Actual Shear..... Allowable Mmax Between @ Top Support Top & Base @ Base of Wall Stem OK Stem OK Stem OK = 10.00 ft 4.02 ft 0.00 ft _ # 5 # 5 # 5 = 10.00 in 9.00 in 18.00 in = Center . Center Center = 4.00 in 4.00 in 4.00 in Rebar Lap Required. Rebar embedment Into footing 0,001 0.407 0.000 6.4 ft-# 2,717.5 ft-# 0.0 ft- # 6,083.7 ft-# 6,684.0 ft- # 3,531.Oft-# 1,020.6 Ibs 1,631.4 ibs 21.26 psi 33.99 psi 93.11 psi 93.11 psi 21.36 in 21.36In - 7.28 in Other Acceptable Sizes & Spacings: Toe: # 5 @ 18.00 in -or- Not req'd, Mu < S' Fr Heel:# 5 @ 26,25 In -or- Not req'd, Mu < S " Fr Key'. Slab.Resists Sliding -or- Slab Resists Sliding -No Force on 11 -� . QED AUG 2 9 2008 BUILDING DEPT. Title: Hilliard Residence Job # 07048 Dsgnr: AKE Date: 5:07PM, 7 AUG 08 Description Scope: Code Ref: ACI 318-02, 1997 UBC, 2003 IBC, 2003 NFPA 5000 Rev: SM014 Page 2 User KW-0601622-VerB.B.0.1-Deo-20Design Restrained Retaining Wall Desi n 07048.ecw Caleulatlons (c)1983-2003 ENERCALC Engineering Software a Description Crawl Space B w/ Slide-.Dec07 Summary of Forces on Footing : Slab RESISTS sliding, stem is PINNED at Forces acting on footing soil pressure (taking moments about front of footing to find eccentricity) Surcharge Over Heel = Ibs ft ft-# Axial Dead Load on Stem = 900.0lbs 1.83 ft 1,650.Oft-# Sol] Over Toe = 82.5lbs 0.75 It 61.9ft-# Surcharge Over Toe = Ibs ft ft-# Stem Weight = 990.8lbs 1.83 ft 1,816.5ft-# Soil Over Heel = 1,012.0lbs 2.93 ft 2,968.5ft-# Footing Weight = 581.2lbs 1.85 ft 1,075.3ft-# Total Vertical Force = 3,566.5lbs Moment = 7,572.2ft-# Net Moment Used For Soil Pressure Calculations 474.1 ft-# At16 2 9 2008 BUKDING DEPT. u (2) #5 CONT. i po 2X10 LEDGER W/ 5/8"0 EPDXY ANCHORS 0 12" o.c. (5"EMBED) FLOOR JOIST 2x8 PT. SILL PLATE W/ 3/4"x10" A.B. 4'-0" O.C. & 12" FROM ENDS, MIN. 7" EMBEDMENT OR AS REQUIRED BY SHEAR WALL SCHEDULE I le ° d I r ° 14 I e #5 ® 15" O.C. EA. WAY I' ° I°d° I I a° ° °I• i I h S-6" I .I 0 (2) #5 CONT. ® TOP d #4 ® 12" O.C. I° 1° a—-- _: — 4" CONCRETE SLAB OVER 20 MIL VAPOR BARRIER AND 4" WASHED ROCK. dal, d,i °I #5 ® 15" O.C. EA. WAY ICI a I I° Id I ({� 1 WATERPROOFING ON GARAGE WALL x d z.—, #5 ® 12O.C. EA. WAY 4" 8" 8" 4" , FOUNDATION ZVAULT DETAIL 5// FDDET2 SCALE: 1 "= 1'-0" 4R06'11 S NOTED RECEIVED ERING AUG 2 9 ?000 FILE DBUILDING DEPT. LOOP FERREL ® 48" O.C. W/ 1/2" 0 ALL THREAD TIGHTLINE STORM DRAIN FND. DRAIN q� . F;�sc53 o �SrONpL -��C' EXPIRES 5/17/6704 Cornerstone Geotechnical, Inc. Consulting Geotechnical Engineers & Geologists September 12, 2008 Mr. Ron Hilliard 6608 — 216`h Street SW, Suite 304 Mountlake Terrace, Washington 98043 Mass Excavation Cut Volume 156`h Street Southwest and 75`h Place West Parcel No. 00500900000101 Edmonds, Washington CG File No. 2212 Dear Mr. Hilliard: Z5"/5 OP401.(J(� C/DS App. ' 1i,; .ASS NOFEU BY .. dINEE!RING r Dat , (i't�dR RECEIVED SEP 12 298 BUILDING DEPT. This letter provides our review of the excavation quantities at your residential site at the intersection of 1561h Street Southwest and 75`h Place West in Edmonds, Washington. We have prepared a geotechnical report for the project dated January 22, 2007. We have been providing on -going construction observation services for the project during foundation subgrade preparation and building excavation. We have been requested to evaluate yardage quantities excavated to date for the project. We have been provided by Robert Pusey, PLS of Pacific Geomatic Services, Inc. an electronic copy of a plan sheet titled "Excavation Sections for Ron Hilliard, Lunds Gulch Road", that shows 6 planned cross sections with existing ground elevations before and after development. This plan indicates that approximately 382 cubic yards was to be cut at the site. We reviewed elevation stakes and horizontal dimensions of the existing concrete footings in the field and it is our opinion that the east side of the foundation excavation sections provided to us are reasonable with existing cut dimensions at the site. Our observations indicated that the west side of the excavation continued outside of the vertical lines shown on the provided cross sections. This amount of soil was not included in the original calculations. We therefore calculated this volume based on the sections provided and our observations of what exists in the field. Our calculations indicate that an additional 83 yards were excavated. This would make the 17625 —130th Avenue NE, C102, Woodinville, WA 98072 • Phone: 425-844-1977 • Fax: 425-844-1987 STREET FILE Mass Excavation Cut Volume 1561h Street Southwest and 75`' Place West Parcel No. 00500900000101 Edmonds, Washington September 12, 2008 CG File No. 2212 Page 2 total yardage of excavated material to be 465 yards. Some of this material currently remains on site and will be used for backfill behind basement and landscaping walls. We trust this letter provides the information you need at this time. We appreciate the opportunity to be of continued service to you. If there are any questions concerning this letter or if we can provide additional services, please call. Sincerely, Cornerstone Geotechnical, Inc. 11 Charles P. 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The. purpose of the Checklist is to enable City staff to determine whether any potential Critical Areas are, dr 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). JZSC:5 �� MAY 0 8 2006 Date Received:. O City Receipt #: Critical Areas File #: ' aZ606 �()� Critical Areas Checklist Fee: $135.00 Date Mailed to ADnlicant: �,13--06 A property owner, or his/her authorized representative, must fill out the checklist, sign and date it, 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. Please submit a vicinity map, along with the signed copy of this form to assist City staff in finding and locating the specific piece of property described on this form. In addition, the applicant shall include other . pertinent information (e.g. site plan, topography map, etc.) or studies in conjunction with this Checklist to assistant staff in completing their preliminary assessment of the site. The undersigned applid %iWW S ieirs, and assigns, in consideration on 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 part upon false, misleading, inaccurate or incomplete information furnished by the applicant, his/her/its agents or employees. By my signature, I certify that the information and a ibits herewith submitted are true and correct to the best of my knowledge and that I am authorized to fil c on the behalf of the owner as listed below. SIGNATURE OF APPLWANT/AGENT DATE S -Q 4 - O (o Property Owner's Authorization By my signature, I certify that I have authorized the above Applicant/Agent to apply for the subject land use application, and grant my permission for the public officials and the staff of the City of Edmonds to enter the subject property for the purposes of inspection and postin is application. SIGNATURE OF OWNER - DATE S ' O - O PLEASE PRINT CLEARLY Owner/Applicant: Name 202, ,l •2-3M Street Address L.4QAvu3O0b WA 9,o Z G City State Zip Telephone: AZG -7-7 j —06'ci (o Applicant Representative: Name Street Address City State Zip Telephone: Email address (optional): Y'9_5 QS�1-�& V •7c!�,), Email Address (optional): • \ .. #P20 Critical Areas Checklist CA File No. �° -0058 Site Information (soils/topography/hydrology/vegetation) 1. Site Address/ Location: S eS 1 1�, `1 ST -4% *i?L , . W , E- nA) L" �a 2. Property Tax Account Number: �,��q (`1� gnc� 1_4n 1 3. 4. Approximate Site Size (acres or square feet): Is this site currently developed? _ yes; _X no. 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). X Steep: grades of greater than 30% present on site (a vertical rise" of '10-feet over a horizontal distance of less than 33-feet). r Other (please describe): 6. Site contains areas of year-round standing water: ; Approx. Depth: 7. Site contains areas of seasonal standing water: ; Approx. Depth: What season(s) of the year? 8. Site is in the floodway floodplain of a water course. 9. Site contains a creek or an area where water flows across the grounds surface? Flows are year-round? Flows are seasonal? (What time of year? ). 10. Site is primarily: forested ; meadow ;shrubs ; mixed k_; urban landscaped (lawn, shrubs etc) 11. Obvious wetland is present on site: For City Staff Use Only �= 1. Plan Check Number, if applicable? 2. Site is Zoned? RS- 20 3. SCS mapped soil type(s)? 4 - . A -3 11 (CULL-11 A r�s y (S ' 1y^ 7 S io 9 ' r1Wb v. Is-,tyrM(". �y Z 447 4G,ec[ 4. Critical Areas inventory or C.A. map indicates Critical Area on site? `fc; - (_Ands 1:,: f+j zArA AAei 5 t.e.� erupt 5. e.r;:cn 6-7 Wl/\f— W A C,-tzk - k �Il(llfcGmseiv�.h� Art, 5. Site within designated earth subsidence landslide hazard area? _ Yes / DETERMINATION ✓ STUDY REQUIRED WAIVER Reviewed by: Date: 9X0 Critical Areas Check]ist/3.25.2004 } ti -'� CITY OF EDMONDS CRITICAL AREAS RECONNAISSANCE REPORT Site Location: 15515 — 751h Place W. Tax Acct. Number: 5009 000 001 01 Determination: Study Required Determination #: CA-06-58 Applicant: Ron Hilliard Owner: Ron Hilliard CRITICAL AREAS RECONNAISSANCE REPORT: STUDY REQUIRED (CA-06-58) During review and inspection of the subject site, it was found that the site may contain critical areas, including Geologically Hazardous areas and'Wildlife Habitat pursuant to Chapter 23.40 of.the Edmonds Community Development Code (ECDC). 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 submit the entire study with your specific development application. Please review the minimum report requirements for all types of -Critical Areas which 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 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 — LANDSLIDE HAZARD AREA It appears that this property contains or is adjacent to a Landslide Hazard Area. • 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). • Landslide Hazard Areas are further defined and illustrated in (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 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. STUDY REQUIREMENT — FISH AND WILDLIFE HABITAT Since the sight is within a mapped wildlife habitat area, the City would like to preserve as much of the native vegetation as possible. DEVELOPMENT PROPOSALS ON A SITE WITH WILDLIFE HABITAT The applicant must submit a clearing/tree cutting plan with any development permit. Tree cutting and clearing of native vegetation shall be limited to the footprint of development. 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. 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. - Name ature 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. 2