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15605 75TH PL W (2).PDF15605 75TH PL W 0 6 - ADDRESS: TAX ACCOUNT/PARCEL #: BUILDING PERMIT (NEW STRUCTURE) #: 62 COVENANTS (RECORDED) FOR: CRITICAL AREAS #: & ,, DETERMINATION: ❑ Conditional Waiver Study Required ❑ Waiver CRITICAL AREAS #: DETERMINATION: ❑ Conditional Waiver ❑ Study Required ❑ Waiver DISCRETIONARY PERMIT #'S: DRAINAGE PLAN DATED: PARKING AGREEMENTS DATED: EASEMENT(S) RECORD FOR: PERMITS (OTHER — list permit #'s): PLANNING DATA CHECKLIST DATED: SCALED PLOT PLAN DATED:/ D SEWER LID FEE $: LID #: SHORT PLAT FILE: LOT: BLOCK: SIDE SEWER AS BUILT DATED: SIDE SEWER PERMIT(S) #: GEOTECH REPORT DATED: STREET USE/ENCROACHMENT PR&41T #: FOR: WATER METER TAP CARD DATED: OTHER: L:\TEMP\DST's\Forms\Jana's Street File Checklist 5-14-08.doc 0 0 CITY OF EDMONDS GARY HAAKEN SO MAYOR 121 5TH AVENUE NORTH • EDMONDS, WA 98020 • (425) 771-0220 • FAX (425) 771-0221 Website: wwwo.edmonds.wa.us DEVELOPMENT SERVICES DEPARTMENT Ih c 1890 Planning * Building • Engineering January 27, 2009 Chris Hammond 15605 - 75th Place West Edmonds, WA 98026 Subject: veterrninaiion reyardiny G'iiic;-Jt A1ecs %1'tCt,kli5t: CRA20-0001-105 Dear Applicant: Enclosed please find a copy of the Critical Areas Checklist you submitted. The `DETERMINATION" reached by the City is located on the reverse side of the form (bottom of page). IT IS VERY IMPORTANT FOR YOU TO. RETAIN A COPY OF THIS CRITICAL AREAS "DETERMINATION" FOR YOUR RECORDS. Please examine this Determination for additional requirements. You may need to submit additional information such as an Environmental Checklist or Critical Areas Study. The Determination for the Critical Areas Checklist you submitted is a site -specific determination, not a project -specific determination. YOU MUST SUBMIT A COPY OF THE CRITICAL AREAS CHECKLIST and DETERMINATION WITH • ALL PERMIT APPLICATIONS OR YOUR APPLICATION WILL NOT BE PROCESSED. Permit applications include the following: Building Permits Conditional Use Permits Subdivisions Variances Applications to the ADB* Land Use Applications Any other development permit applications. Thank you, Planning Secretary C: Steve Barnes, Cornerstone Architect Group *Architectural Design Board Enclosure RECEI D FEB - 6 2009 DEVHAPMENTSMICES OTR- CITY OF EDMONDS C_\My Documents\LINDA\Linda's CACL.doc 1. 0 Incorporated August 11, 1890 • • #P20 • �° EDO tia City of Edmonds Development Services Department Planning Division Phone: 425.771.0220 10C_ i gqo 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). Date Received: City Receipt #: Critical Areas File #: Critical Areas Checklist Fee:1�� Date Mailed to Applicant- , 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 applicant, and his/her/its heirs, 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 this application on the behalf of the owner as listed below_ SIGNATURE OF APPLICANT/AGENT 5 DATE f ^2-6/ 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 posting attendant to this application. SIGNATURE OF OWNER G< DATE ✓ `� — Owner/Applicant: dame r Street Address City State zip Telephone:_ �(rj - M Email address (optional): Applicant Representative: Name Street Address City State Zip Telephone: ZUfiT1C SG�G Email Address (optional):4kxia""C'V memo loan(,4, Cfi�t CITY OF EDMONDS CRITICAL AREAS RECONNAISSANCE REPORT Site Location: 15605 75t' Place West Tax Acct. Number: 00513100002404 Determination: Study Required Determination #: CRA-2009-0005 Applicant: Steve Barnes Owner: Chris Hammond BACKGROUND During review and inspection of the subject site, it was found that the site contains and/or is adjacent to critical areas, including Geologically Hazardous Areas and Fish and Wildlife Habitat Conservation Areas, pursuant to Chapters 23.40, 23.80 and 23.90 of the Edmonds Community Development Code (ECDC)_ Additionally, the parcel is located within the North Edmonds Earth Subsidence and Landslide Hazard Area. The subject parcel slopes very steeply east to west towards Puget Sound. According to the City's LIDAR data, the steepness of the slope varies from in excess of 50% towards the east and falls quickly to a more level area on the western half of the lot. The parcel is also classified as being within a mapped salmon habitat area near Meadowdale Park/Lunds Gulch. This study applies to the entire subject parcel. Depending on the location and type of project proposed relative to the identified critical areas, certain studies and reports may be required. ALLOWED ACTIVITIES AND EXEMPT DEVELOPMENT PROPOSALS Certain activities are allowed in or near critical area buffers as specified in ECDC 23.40.220. Similarly, certain development proposals may be exempt from Critical Areas Requirements (ECDC 23.40.230). If you have any questions about whether your proposed development qualifies as an allowed or exempt activity, please contact a Planner for more information. GENERAL CRITICAL AREAS REPORT REQUIREMENTS Critical Areas Reports identify, classify, and delineate any areas on or adjacent to the subject property that may qualify as critical areas. They also assess these areas and identify any potential impacts resulting from your specific development proposal. If a specific development proposal results in an alteration to a critical area, the critical areas report will also contain a mitigation plan. You have the option of completing the portion of the study that classifies and delineates the critical areas and waiting until you have a specific development proposal to complete the study. You may also choose to submit the entire study with your specific development application. • Please review the minimum report requirements for all types of Critical Areas that are listed in ECDC 23.40.090.D. There are additional report requirements for different types of critical areas (see below). • Note that it is important for the report to be prepared by a qualified professional as defined in the ordinance. There are options on how to complete a critical areas study, and there is an approved list of consultants that you may choose from. You may contact the Planning Division for more information. • General Mitigation Requirements for all Critical Areas are discussed in ECDC 23.40.110 through 23.40.140. f� STUDY REQUIREMENT — EROSION HAZARD AREA It appears that this property contains or is adjacent to an Erosion Hazard Area. Erosion Hazard Areas include: • Those areas with Alderwood and Everett series soils on slopes of 15 percent or greater. • Any area with slopes of 15 percent or greater and impermeable soils interbedded with granular soils and springs or ground water seepage. • Areas with significant visible evidence of ground water seepage, and which also include existing landslide deposits regardless of slope_ DEVELOPMENT PROPOSALS ASSOCIATED WITH EROSION HAZARD AREAS Development within an Erosion Hazard Area must meet additional criteria. • For erosion hazard areas with suitable slope stability, the only critical area study needed is an erosion and sediment control plan prepared in compliance with the requirements set forth in Chapter 18.30 ECDC as part of the construction documents. This option is at the director's discretion, per Edmonds Community Development Code section 20.80.050.G. • In areas where the slope stability is not suitable, projects within Erosion Hazard Areas will require a report by a licensed Geotechnical Engineer or other qualified professional. Note that it is important for the report to be prepared by a qualified professional as defined in the ordinance. • Report requirements are given in ECDC 23.80.050, and more generally in ECDC 23.40.090. D. • Development standards are given in ECDC 23.80.060 and 23.80.070. STUDY REQUIREMENT — LANDSLIDE HAZARD AREA It appears that this property contains or is adjacent to a Landslide Hazard Area. • A Landslide Hazard Area is any area with a slope of forty percent (40%) or steeper and with a vertical relief of ten (10) or more feet (except areas composed of consolidated bedrock). • Landslide Hazard Areas are further defined and illustrated in ECDC 23.80.020:B. • In addition to the general requirements for Critical Areas reports referenced above, specific Critical Area report requirements for Landslide Hazard Areas are provided in ECDC 23.80.050. DEVELOPMENT PROPOSALS ASSOCIATED WITH LANDSLIDE HAZARD AREAS Development is restricted within a Landslide Hazard Area and its buffer. • Projects that will intrude into these areas will require a report by a licensed Geotechnical Engineer. • The criteria that are applied depend on the amount that the buffer is reduced. • The buffer can be reduced to a minimum often (10) feet (with an additional 15' building setback per ECDC 23.40.280) if a report is prepared that meets the standards listed in 2 ECDC 23.80.050. The alteration must also meet the requirements listed in ECDC 23.80.060. • In addition, proposals to reduce the buffer to less than ten (10) feet must comply with the design standards listed in ECDC 23.80.070.A.3. STUDY REQUIREMENT — FISH AND WILDLIFE HABITAT CONSERVATION AREAS Since the site is located within a mapped fish and wildlife habitat conservation area, the City would like to preserve as much of the native vegetation as possible. DEVELOPMENT PROPOSALS ON A SITE WITH FISH AND WILDLIFE HABITAT CONSERVATION AREAS The applicant must submit a clearing/tree cutting plan with any development permit, if applicable. Tree cutting and clearing of native vegetation shall be limited to the footprint of development. NORTH EDMONDS EARTH SUBSIDENCE LANDSLIDE HAZARD AREA The subject site is located within the North Edmonds Earth Subsidence Landslide Hazard Area (ESLHA). Contact the Building Division for requirements related to the ESLHA. If you have any questions about this determination, please contact a Planner for more information. 7 Name Si 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. OF CU,y Critical Areas Map File Number: CRA-2009-0005 ESLHA Boundary (approximate) 15605 75th Place West 114 1 inch equals 75 feet 'f90 PLANNING DATA STREET FILE SINGLE FAMILY RESIDENTIAL Name: HC60 fV7 0fl d Dale: Site Address: ftp manCheck # - Project Description- 5-F9 A d -OCSL H1q Reduced Site Plan Provided.- YES Zoning: Map Page: Corner Lot-- (YES Flag Lot: (YES Critical Areas Determination -Ce A-2,909oca-0 S- V-Study Required 0 waiver SEPA Determination: k_Lxempt C, �� ' — osC ul V'� El Needed (for over 500 cubic yards of grading) 0 Fee El Checklist El APO List with notarized form 8eqimed Stre VJ Si Side- Rear: Actual Setbacks Street: ] Side: ar-- ❑ Detached Structures- ❑ Rockeries: s, )nd C-61 rS" �� ❑ Fences/Trellises: ❑ Bay Windows/Projecting Modulation: 5#m Stairs/Deck: It, Datum Elevation. - Actual Height: Datum Point: C Maximum Height Allowed: 2S- t Other Parking Required: _Z_ Parking Provided: Lot Area: Iq 4S / 4 Maximum Lot Coverage: 35% Proposed: Lot Coverage Calculations: 4z, ADU Created: (YES Subdivision: Legal Nonconforming Land Use Determination Issued: (YES 1 Comments -e &� UUI C t-rA Cl# A) 6 (Zr_C& C 25 C 5 rp 0AA Ok--- Plan Review By: I LCd rm;trle (ecv- fldn lq Data f-(WM 04 -11106JOC Associated Earth Sciences, Inc. EDM 09-03 H i;� 0 a(e6rabnq O' er25 Veaff o f S'er^ w E C[ Y co February 6, 2009 EECE Project No. KE080287A l Chris and Karen Hammond 15605 75" Place West Edmonds, Washington 98026 i Subject: Geotechnical Hazard Identification/Declaration / 4 and Mitigation Statement of Risk Proposed Hammond Residence Addition 15605 75' Place West Edmonds, Washington Parcel No. 00500900000101 t� References: Cornerstone Architectural Group E" Architectural and Foundation Plans Dated December 2008 and January 2009 F . Peterson, Strehle, Martinson, Inc. Structural Engineers E=✓l��V� Associated Earth Sciences, Inc. 6 2009 "Subsurface Exploration, Geologic Hazard, FEB DEVELOPMENTSERVICES CTR. and Preliminary Geotechnical Engineering Report" CITY OF EDMONDS Dated August 1, 2008 Dear Mr. and Mrs. Hammond: Associated Earth Sciences, Inc. (AESI) has reviewed the above -referenced project plans. In accordance with City of Edmonds requirements in earth subsidence and landslide hazard areas, we have prepared the following statements: • In our judgment, the plans prepared by the architectural designer and structural engineer conform to the recommendations in our August 1, 2008 geotechnical report. • In our opinion, the risk of damage to the proposed development, or to adjacent properties from soil instability will be minimal, subject to the conditions set forth in the report, and the proposed development will not increase the potential for soil movement. Kirkland Everett Tacoma 425-827-7701 425-259-0522 253-722-2992 www.aesgeo.com • In our opinion, the probabilities for earth movement on the property within a 25-year period are approximately: a 30 percent chance of occurrence for slumps in previously failed material and a 2 percent chance of occurrence for debris avalanches from encroaching landslide materials. These values were determined by using the values shown on the City's Landslide Hazard Map, developed by Lowe Associates and updated by GeoEngineers. In our opinion, the values are still applicable since the drainage in the site vicinity has been improved since these studies have been performed and, therefore, should not increase. • In our opinion, the erosion and sediment control plan should be adequate for the proposed improvements, provided the contractor is diligent in inspecting and maintaining the best management practices (BMPs). Furthermore, AESI will provide construction monitoring services to periodically observe the effectiveness of the BMPs, and recommend modifications, if necessary. • As discussed on Page 10 of our August 1, 2008 geotechnical report, the subject site lies within Zones B and C, as described by the "2007 Landau Summary Report." The new addition will be located only within Zone B. Zone C hazards would include debris flows initiating from the steep slope to the east of the proposed addition, which will be mitigated by the minimum 3-foot-high concrete catchment wall (i.e., raised foundation stemwall) on the east side of the addition. In our opinion, this location will not significantly increase the risk to the addition since the 3-foot-high catchment wall will mitigate debris flow risk after such flows reach the backyard area. Zone B hazards include movement of the ancient landslide mass underneath the new addition. This risk has been partially mitigated by suitable foundation subgrade preparation (i.e., 2 feet of structural fill under the new foundations), and use of a grid -connected footing system to mitigate differential displacement. See the following paragraph and the above - referenced geotechnical report for additional information. • The subject site is located within the North Edmonds Earth Subsidence and Landslide Hazard Area (NEESLHA) formerly known as the Meadowdale Earth Subsidence and Landslide Hazard Area, which is a complex mix of ancient, large-scale earth movements and recent shallow slides. Therefore, it is our opinion that it is not practical for one lot owner to fully mitigate the risk of deep-seated or large-scale earth movement. The risks not fully mitigated include unusually large debris flow avalanches, with trees, boulders, and other projectiles that may penetrate the wooden structure of the house, and large-scale earth movements of the foundation subgrade soils underneath the house. The main purpose of the grid -foundation is to prevent collapse of the addition should the ground beneath move, and not to prevent the addition from moving with large-scale earth movements. 2 We trust that this letter meets your needs. Please call if you have any questions. Sincerely, ASSOCIATED EARTH SCIENCES, INC. Kirkland, Washington �Crw— � Scott R. Hannah, P.G., P.E.G. Senior Geologist cc: Steve Barnes Cornerstone Architectural Group 6161 NE 175`h Street, Suite 101 Kenmore, Washington 98028 SRHAd KE080287A3 Projects\20080287W E\ W P �pN Mctij,C, � of WAS y c 9 ccy��2`�° 1' 9 33222 F FGIST1*' G� G. Aaron McMichael, P.E., P.E.G. Associate Engineer 3 Geotechnical Engineering Water Resources Environmental Assessments and Remediation Sustainable Development Services Geologic Assessments Associated Earth Sciences, Inc. Ce��-ahy aUe�.2�' �e�r�s'of les�r�>ce Subsurface Exploration, Geologic Hazard, and Preliminary Geotechnical Engineering Report WE and Residence Addition Edmonds, Washington Prepared for Chris Hammond Project No. KE080287A August 1, 2008 RECEIVED FEB - 6 2009 l DEVELOPMENT SERVICES CTR. 1 CI7Y OF EDMONDS STRE"I"ET111- FILE Associated Earth Sciences, Inc. [ad 5:1 N� W1 W &46rab Owr asf o S' mce � z� �ef August 1 2008 ' Project No. KE080287A I Mr. Chris Hammond 15605 75`h Place West Edmonds, Washington 98020 Subject: Subsurface Exploration, Geologic Hazard, and Geotechnical Engineering Study Hammond Residence Addition 15605 75`h Place West Edmonds, Washington Parcel Number: 00513100002404 1 ' Dear Mr. Hammond: We are pleased to present the enclosed copies of the above -referenced report. This report summarizes the results of our subsurface exploration, geologic hazard, and geotechnical engineering studies and offers recommendations for the preliminary design and development of the proposed project. Our recommendations are preliminary in that construction details have not been finalized at the time of this report. We have enjoyed working with you on this study and are confident that the recommendations presented in this report will aid in the successful completion of your project. If you should have any questions or if we can be of additional help to you, please do not hesitate to call. ' Sincerely, ASSOCIATED EARTH SCIENCES, INC. Kirkland, Washington G e6" Jo D. Hansen Senior Staff Geologist 1 7DHAI KE0 2 Projects\20cLs\20 080287\KE\W P Kirkland M Everett 0 Tacoma 425-827-7701 425-259-0522 253-722-2992 www.aesgeo.com SUBSURFACE EXPLORATION, GEOLOGIC HAZARD, AND PRELIMINARY GEOTECHNICAL ENGINEERING REPORT Hammond Residence Addition Edmonds, Washington Prepared for: Chris Hammond 15605 75' Place West Edmonds, Washington Prepared by: Associated Earth Sciences, Inc. 911 5' Avenue, Suite 100 Kirkland, Washington 98033 425-827-7701 Fax: 425-827-5424 August 1, 2008 Project No. KE080287A Subsurface Exploration, Geologic Hazard, and Hammond Residence Addition Preliminary Geotechnical Engineering Report Edmonds Washington Project and Site Conditions ' I. PROJECT AND SITE CONDITIONS 1.0 INTRODUCTION This report presents the results of Associated Earth Sciences, Inc.'s (AESI's) subsurface exploration, geologic hazard, and geotechnical engineering study for the Hammond Residence Addition, located in Edmonds, Washington (Figure 1). The existing site features, including topographic contours and the approximate locations of the explorations accomplished for this study are presented on the "Site and Exploration Plan," Figure 2. The Hammond Residence is located within the North Edmonds Earth Subsidence and Landslide Hazard Area (NEESLHA). As such, this report has been completed to assess site landslide hazards and mitigation design recommendations for the proposed addition. iThe recommendations in this report are considered to be preliminary because grading plans and construction details were not finalized at the time of this study. Once development plans are ' substantially complete, the conclusions and recommendations in this report should be reviewed and modified, or verified as appropriate. 1 1.1 Purpose and Scope The purpose of this study was to provide subsurface data to be used in the preliminary design iand development of the subject project. Our study included a review of available geologic ■ literature, excavation of exploration pits and hand borings, and performing geologic studies to assess the type, thickness, distribution, and physical properties of the subsurface sediments and ' shallow ground water conditions. Geotechnical engineering studies were also conducted to assess the type of suitable foundation, allowable foundation soil bearing pressures, anticipated ' settlements, basement/retaining wall lateral pressures, floor support recommendations, geologic hazards (including the North Edmonds Earth Subsidence and Landslide Hazard Area), and drainage considerations. This report summarizes our current fieldwork and offers development recommendations based on our present understanding of the project. 1.2 Authorization i1 Written authorization to proceed with this study was granted by Mr. Chris Hammond. Our study was accomplished in general accordance with our proposal dated May 4, 2008. This report has been prepared for the exclusive use of Chris Hammond and his agents, for specific application to this project. Within the limitations of scope, schedule, and budget, our services have been performed in accordance with generally accepted geotechnical engineering and August 1, 2008 ASSOCIATED EARTH SCIENCES, INC. JDHRb - KE080287A2 - Projects 1200802871KEI WP Page 1 Subsurface Exploration, Geologic Hazard, and Hammond Residence Addition Preliminary Geotechnical Engineering Report Edmonds, Washington Project and Site Conditions ' engineering geology practices in effect in this area at the time our report was prepared. No other warranty, express or implied, is made. 2.0 PROJECT AND SITE DESCRIPTION ' 2.1 Site Description IF C 1 The subject site consists of a rectangular shaped parcel with an existing one-story single family residence located at 15605 75' Place West (Figure 1). The areas immediately surrounding the existing home are relatively flat and vegetated by lawn and other landscaping. The property is bounded on the west by 75`h Place West, on the north by a vacant single-family lot, and on the south by an existing single-family residence. The Burlington Northern Railroad right-of-way is located adjacent the shoreline of Puget Sound west of the project site and adjacent properties. A steep, west facing slope runs north/south along the eastern margins of the subject property. The slope is heavily vegetated with stands of both deciduous and coniferous trees and thick underbrush. A site plan provided by the client includes topographic contours over the proposed building site and adjacent steep slope area to the east. Review of the topographic contours shown on this site plan indicate that slope gradients in the mapped portion of the steeper, eastern area range from approximately 40 to 65 percent. A visual reconnaissance of this portion of the site found that topographic gradients are similar (i.e. approximately 40 to 60 percent). The parcels total area is approximately 0.34 acres. 2.2 Project Description Our understanding of the project plans is based on discussions with Mr. Chris Hammond. It is our understanding that conceptual plans call for the construction of a new, approximately 1,500 square foot, two-story addition to the south end of the existing residence, approximately where shown in Figure 2. We understand that the location of the addition as shown is approximate and construction details, such as the proposed shallow cut depths, are not known at this time. 2.3 Site Observations Our site observations were made after the excavation of pits and hand auger borings during our visit on the 13`h of June. The following sections describe our visual observations. 2.4 Geologic Reconnaissance The existing house and proposed addition are located on a flat bench on the lower half of a large slope system, the top of which is on the order of 100 feet above and 150 feet to the east. August 1, 2008 ASSOCIATED EARTH SCIENCES, INC. !DH/tb - KE080287A2 - Projects1200802871KEMP Page 2 ' Subsurface Exploration, Geologic Hazard, and Hammond Residence Addition Preliminary Geotechnical Engineering Report Edmonds, Washington Project and Site Conditions 1 r� fl I I F The slope system drops down to the west from 75t' Place West to the Puget Sound across a vertical relief on the order of 100 feet. The steep slope near the eastern margins of the property ranges from 40 to 60 percent inclinations, based on visual estimates. An over - steepened area interpreted to be an old slide scarp was observed directly east of the project site approximately 50 feet above the existing dwelling. The scarp was visually estimated to be on the order of 40 feet in length and 5 to 10 feet in height. The slope is densely vegetated with ferns, shrubs, and stands of both deciduous and coniferous trees. Most of the deciduous trees had bowed trunks indicating slope creep, but several coniferous trees higher up the slope appeared relatively straight. An approximately 4-foot-high concrete wall for the existing home's carport is located at the toe of the slope near the northeast portions of the project site. The toe of the steep slope is approximately 15 to 20 east of the existing dwelling. On December 31, 1996, a slide occurred immediately east of the subject site, where a new cistern structure and storm line have since been installed. The slide was observed as a shallow slough event, on the order of 1 to 2 feet in thickness. In conversations with the property owner, this failure was later found tied to the construction and/or draining of a swimming pool located above the top of slope and exceptionally heavy precipitation the month prior. No further signs of slope failure or sloughing were observed during our visit and the area has since naturally revegetated with thick underbrush and vine maples. This slope area and scarp are part of the North Edmonds Earth Subsidence and Landslide Hazard Area (NEESLHA), formerly known as the Meadowdale Earth Subsidence Landslide Hazard Area. This approximately 3,000-foot long by 500- to 800-foot-wide landslide complex is comprised of large blocks of both Vashon-age glacial sediments (till and outwash soils deposited during the Fraser glaciation) and pre-Vashon-age non -glacial sediments (generally silts deposited before the Fraser glaciation) in conjunction with recent shallow debris flow failures comprised of colluvium. Studies by others have generally concluded that the deep- seated movements have stopped or been minimal over the last few decades since the toe of the slope system has been buttressed by the railroad ballast and drainage improvements have kept ground water levels relatively low. Shallow movements in the lower, previously failed portions of the slide complex and debris flows in the steep upper portions near the ancient slide scarp continue to experience occasional failures in recent years. Since this landslide complex is well -documented and studied by others over the last half century, a complete history is beyond the scope of this report. Additional information regarding this slide complex can be found in the studies by others listed in the "Literature Review" section of this letter. In the streets and unimproved right-of-ways at the top of the slope, we observed asphalt berms and catch basins that appeared designed to collect surface water from the streets and easements. We understand that drainage improvements were completed near the upper, August 1, 2008 ASSOCIATED EARTH SCIENCES, INC. JDH/tb - KE080287A2 - Projects 1200802871KEI WP Page 3 Subsurface Exploration, Geologic Hazard, and Hammond Residence Addition Preliminary Geotechnical Engineering Report Edmonds, Washington Project and Site Conditions ' developed portions of the slope in the late 1990s after some shallow slides were reported adjacent to several surrounding properties. ' 2.5 Existing Structure Reconnaissance ' During our visit, we did not observe signs of distress in the existing house structure or adjacent roadway section, such as cracks in the existing houses brick fagade or slumped roadway areas. The owner informed us that he was not aware of problems with sticking doors or windows or other indicators of settlement. 1 3.0 SUBSURFACE EXPLORATION 1 Our field study included the observation of two exploration pits and two hand auger borings to gain subsurface information about the site. The various types of sediments, as well as the depths where characteristics of the sediments changed, are indicated on the exploration logs ' presented in the Appendix. The depths indicated on the logs where conditions changed may represent gradational variations between sediment types. Our explorations were approximately located in the field relative to known site features shown on a topographic site plan provided by the client. The approximate locations of the explorations are shown on the "Site and Exploration Plan, " Figure 2. ' The conclusions and recommendations presented in this report are based, in part, on the conditions encountered in the exploration pits and hand auger borings completed for this study. The number, location, and depths of the explorations were completed within site and budgetary 1 constraints. Because of the nature of exploratory work below ground, extrapolation of subsurface conditions beyond the field explorations is necessary. Differing subsurface ' conditions may be present outside of the area of the field explorations due to the random nature of deposition and the alteration of topography by past grading and/or filling. The nature and extent of any variations between the field explorations may not become fully evident until ' construction. If variations are observed at that time, it may be necessary to re-evaluate specific recommendations in this report and make appropriate changes. 1 3.1 Exploration Pits Exploration pits were excavated with a client provided backhoe near south margins of the proposed addition area (EP-1 and EP-2). The pits permitted direct, visual observation of subsurface conditions. Materials encountered in the exploration pits were studied and classified in the field by an engineering geologist from our firm. All exploration pits were ' August 1, 2008 ASSOCIATED EARTH SCIENCES, INC. JDH/tb - KE080287A2 - Projects1200802871KE1WP Page 4 Subsurface Exploration, Geologic Hazard, and Hammond Residence Addition Preliminary Geotechnical Engineering Report Edmonds, Washington Project and Site Conditions ' backfilled immediately after examination and logging. Selected samples were then transported to our laboratory for further visual classification and testing, as necessary. 3.2 Hand Auger Borings f! 1 Hand auger exploration borings were performed in the steep slope area immediately east of the existing homes concrete patio area (HB-3 and HB-4). The hand borings permitted direct, visual observation of the subsurface conditions and relative thickness/distribution of slope colluvium. Materials encountered in the hand auger exploration borings were studied and classified in the field by an engineering geologist from our firm. All hand borings were backfilled immediately after examination and logging. Selected samples were then transported to our laboratory for further visual classification and testing, as necessary. Literature Review We reviewed our in-house files, select City of Edmonds reports within a 100-foot radius of the subject property, and publicly available exploration data from the GeoMapNW website (http://geomapnw.ess.washington.edu/index.php) at the University of Washington for previous geotechnical studies performed in the project vicinity. Our research revealed exploration logs from the following studies: • "Subsurface Exploration, Geologic Hazards, and Preliminary Geotechnical Engineering Report, Aldridge Short Plat, Edmonds, Washington," dated October 24, 1997 by AESI (from AESI in-house files). This study included the two lots directly across 75' Place West from the project site (15604 751' Place West). Three exploration borings and four exploration pits were performed at the Aldridge site, which generally encountered fill over disturbed silts/clays over very dense fine sands. Slope inclinometers were installed in two of the borings and were measured periodically over a period of approximately 3 years. Measurements indicated shallow, downslope creep of the fill in the upper 10 feet on the order of 1 inch or less over the measurement period, with the majority of the movement occurring near the top of an uncontrolled fill slope on the west side of the property. The site has remained undeveloped at the time of this report. • "Geotechnical Engineering Report, 156' Street Southwest, Edmonds, Washington," dated January 22, 2007 by Cornerstone Geotechnical, Inc. (provided by Cornerstone Architectural Group). This study included the one undeveloped lot immediately north of the project site (east side of 75' and 156th). Four exploration test pits were performed at the site, which generally encountered loose to medium dense silty fine to August 1, 2008 ASSOCIATED EARTH SCIENCES, INC. JDHAb - KE080287A2 - Projects1200802871KEMP Page 5 1 ' Subsurface Exploration, Geologic Hazard, and Hammond Residence Addition Preliminary Geotechnical Engineering Report Edmonds, Washington Project and Site Conditions ' medium sand with trace gravel and organics (fill) over medium dense light brown to gray silty fine sand with varying amounts of gravel. ' • "Revised Geotechnical Report, Proposed Residence at Lots 1 and 2, 75' Place West, Edmonds, Washington," dated January 26, 1994 by Shannon and Wilson, Inc. ' (GeomapNW excerpts only). This study included two lots across 75' Place West to the southwest of the project site (15620 75' Place West). One exploration boring was performed at the site and two exploration pits by Earth Sciences were included in the ' report, which generally encountered fill/slide debris over stiff to hard silts/clays. (According to Snohomish County tax records, a two-story dwelling was constructed in ' 1997). • "Geotechnical Engineering Study, Recent Landslide, 15620 - 72°d Avenue West, ' Edmonds, Washington," dated February 24, 1997 by Geotech Consultants, Inc. (provided by the City of Edmonds). This study included the lot upslope (east) and provided recommendations for stabilizing an adjacent slide scarp area. Three ' exploration borings were performed at the site, which generally encountered dense, gravelly sands over medium dense to dense, silty sands over very dense sands. • "Geotechnical Engineering Services, Landslide on 156' Street Right of Way Near 75' Place West, Edmonds, Washington," dated January 27, 1997 by Landau Associates, Inc. (provided by the City of Edmonds). This letter summarized the observations and recommendations made by representatives of Landau Associates related to the landslide ' that occurred east of the subject site. The study was inconclusive at the time in determining the trigger event for the landslide as either recent heavy precipitation or possible leakage from adjacent drain pipes. • Response to City of Edmonds Letter Dated January 2,1997, Mezich Residence Slide, ' Edmonds, Washington," dated January 13,1997 by Geotechnical Inc. (provided by City of Edmonds). This letter provided recommendations for the stabilization for a slide area near an existing residence upslope of the subject property (7215 1561h Street SW). The ' study included an observation of the slide scarp and found four feet of colluvium over 12 feet of very dense silty sand with gravel over dense fine to medium sand. Further, the study observed two seepages emanating from within the City of Edmonds R.O.W. ' • "Repair of Landlslide, Degan Residence, Edmonds Washington," dated August 9,1999 by Geotech Consultants, Inc. (provided by the City of Edmonds). This study included recommendations for a closely spaced pier wall for a residence southwest of the subject property based predominantly on literature review. August 1, 2008 ASSOCIATED EARTH SCIENCES, INC. JDHItb - KE080287A2 - Projects1200802871KEMP Page 6 ' Subsurface Exploration, Geologic Hazard, and Hammond Residence Addition Preliminary Geotechnical Engineering Report Edmonds, Washington Project and Site Conditions ' • "Geotechnical Engineering Study, Proposed Single Family Residence, Lot 1 Lunds Meadowdale Tract, Edmonds, Washington," dated July 28, 1990 by Terra Associates, ' Inc. (provided by the City of Edmonds). This study included the lot immediately west of the subject site (west side of 156`h and 75'h W). One exploration boring and two exploration test pits were performed at the site, which generally encountered several ' feet of loose medium to coarse grained silty sand (fill), over stiff to hard brown and gray colored silt. ' "Mezich Lot -Addendum to November 13,1989 letter, Edmonds Washington," dated April 13, 1990 by Cascade Geotechnical, Inc. (provided by the City of Edmonds). The study included a lot uphill from the project site (7215 156" Street SW). Two borings were performed at the site, which generally encountered several feet of brown silty sand with gravel (fill), over dense to very dense gray silty sand with gravel, over dense ' to very dense fine to medium grained silty sand. • "Report of Geologic Evaluation, Meadowdale Area, Edmonds, Washington," dated ' September 23, 1968 by Dames & Moore (provided by the City of Edmonds). This study evaluated the overall stability of the area from a geologic standpoint based largely on literature review and surface reconnaissance for installation of a proposed sanitary sewer system. • "Final Report, Landslide Hazards Investigation, Meadowdale Area, Edmonds, ' Washington," dated October 16, 1979 by Roger Lowe Associates, Inc. (provided by the City of Edmonds). This study analyzed the subsurface conditions and slope stability ' based on previous studies and seven borings performed for the study. The study provided a landside hazard map of the Meadowdale area, which quantified landslide risk by type and probability of occurrence in a 25-year period. ' • "Report of Geotechnical Consultation, Property Value Appraisals and Assessments, Meadowdale Landslide Area, Edmonds, Washington," dated February 28, 1985 by GeoEngineers, Inc. (provided by the City of Edmonds). This study updated the probability of landslide occurrences as provided in the 1979 Lowe study after installation of storm and sanitary sewers in the Meadowdale area. ' • "North Edmonds Earth Subsidence and Landslide Hazard Area Summary Report, Edmonds, Washington" dated March 14, 2007 by Landau Associates. This study ' included review of the previous Meadowdale landslide area studies by Lowe and GeoEngineers. Landau also recommended several revisions to critical areas ordinance in earth subsidence and landslide hazard areas, including the designation of five hazard zones based on relative location within the landslide complex. Furthermore, the study ' August 1, 2008 ASSOCIATED EARTH SCIENCES, INC. JDHltb - KE080287A2 - Projects 1200802871KE1WP Page 7 1 Subsurface Exploration, Geologic Hazard, and Hammond Residence Addition Preliminary Geotechnical Engineering Report Edmonds, Washington Project and Site Conditions ' recommends specific report requirements, which will be discussed subsequently in this letter. This study uses the name "North Edmonds Earth Subsidence and Landslide I Hazard Area" (NEESLHA) instead of the previous "Meadowdale" area name. Pertinent information from these studies is discussed in subsequent sections of this letter, ' where appropriate. Relevant logs for the above -referenced explorations have been included in the Appendix of this report. ' 4.0 SUBSURFACE CONDITIONS ' Subsurface conditions at the project site were inferred from the exploration pits and hand auger borings completed for this study, our visual reconnaissance of the site, and review of ' applicable geologic literature. As shown on the exploration logs, we generally encountered 1 to 3 feet of medium dense fill sediments overlying consolidated glacial sediments of variable textural composition. The following section presents more detailed subsurface information ' organized from the youngest to the oldest sediment types. 4.1 Stratigraphy Fill ' Material interpreted to be fill was encountered in both of the explorations pits on the project site. The fill consisted predominantly of medium dense, gray silty sand with variable amounts of gravel, and trace amounts of organic debris. The existing fill soils are not considered ' suitable for foundation support. ' Forest Duff/Topsoil A buried organic topsoil layer was encountered in one of the exploration pits near the SW ' corner of the proposed addition area (EP-1). The topsoil layer was approximately 6 inches thick and was observed below approximately 3 feet of man -placed fill soils. The topsoil layer is not considered suitable for foundation support or for use in a structural fill. ' Old Landslide Block ' Material interpreted to be old landslide soils were encountered in all the explorations on the project site. The old landslide soils consisted chiefly of medium dense to dense, silty fine to ' medium sand with variable amounts of gravel and a disturbed, blocky texture. Exploration pits EP-1 and EP-2 showed signs of slight mottling from 1 to 5.5 feet below the surrounding August 1, 2008 ASSOCIATED EARTH SCIENCES, INC. JDH/tb - KE080287A2 - Projects 1200802871KEI WP Page 8 ' Subsurface Exploration, Geologic Hazard, and Hammond Residence Addition Preliminary Geotechnical Engineering Report Edmonds, Washington Project and Site Conditions ' ground surface. The above noted soils are thought to represent Vashon age lodgement till sediments from higher elevations east of the property. Explorations from the other studies within a 100 foot radius of the project vicinity indicate similar landslide materials that extend well below existing grades in the project area on the order of 30 to 60 feet. ' Review of the regional geologic map titled Preliminary Surficial Geologic Map of the Edmonds East and Edmonds West Quadrangles, Snohomish and King Counties, Washington (Smith, 1975) indicates that the site is underlain by the pre -Fraser geologic units of Whidbey and Double Bluff Formations. Vashon Lodgment Till and Advance Outwash sediments are mapped at higher elevations. Specifically, the site is mapped as being within a large landslide feature with the delineation Qols (old landslide). Our interpretation of the sediments rencountered in our explorations is in general agreement with the regional geologic map. 4.2 Hydrology Ground water seepage was not encountered in any of the exploration pits excavated for our study. In addition, no seepages were observed daylighting on any of the steep slopes on the property during our explorations. If ground water is encountered during construction, it would most likely be found in pockets, perched on less permeable strata within the landslide debris, or as "interflow" at the contact between colluvium and pre -Fraser sediments forming the steep slope. It should be noted that the occurrence and level of this perched ground water seepage may vary in response to such factors as changes in season, precipitation, and both on -site and off -site use. August 1, 2008 ASSOCIATED EARTH SCIENCES, INC. JDH/tb - KE080287A2 - Projects1200802871KEMP Page 9 Subsurface Exploration, Geologic Hazard, and Hammond Residence Addition Preliminary Geotechnical Engineering Report Edmonds, Washington Geologic Hazards and Mitigations II. GEOLOGIC HAZARDS AND MITIGATIONS 5.0 LANDSLIDE HAZARDS AND MITIGATION ' The following discussion of potential geologic hazards is based on the geologic, slope, and shallow ground water conditions as observed and discussed herein. ' The 2007 Landau study divides the potential landsliding locations within the NEESLHA into five zones, A through E. The subject site is located in Zones B and C, with the proposed two- story addition located in Zone B only. Zone B in the vicinity of the subject site is the ' relatively flat bench area between 75' Avenue West and the steep slope area of Zone C to the east. Zone B is described by Landau as including the majority of the landslide mass or ' complex consisting of typically disturbed soils with occasional intact blocks, localized small- scale failures, and potential for large-scale sliding of the slide complex. Zone C is described by Landau as the area near the edge of the landslide complex that is most affected by slides that initiate on the steep slopes on the east side of this zone. Small-scale failures are possible within Zone C, and this zone is the highest risk to public safety. In our opinion, we concur with these generalized assessments and believe the primary risks of earth movement on the subject site that may affect the proposed dwelling will be from debris flows initiating on the steep slopes above the house. Another risk with a much lower likelihood of occurrence would be soil movement under the proposed foundation from reactivation of the main landslide mass. ' Risks of shallow and deep-seated slides, and the associated mitigations, are discussed further in the following paragraphs. ' The potential iandside risk can be divided into two depth categories: shallow and deep. The potential shallow (on the order of 1 to 10 feet thick) landslide risk includes slumps, debris ' avalanches, and earth flows of the colluvial soils and trees on the steep slopes to the east of the project site. The potential deep landslide risks for the site have been identified by previous studies in the site vicinity as continued movement of the ancient landslide blocks. ' The potential for shallow slides is moderate and will be greatest after extended periods of heavy rainfall and/or snow events. Such weather events occurred during the winters of 1996 ' and 1997 and resulted in numerous shallow slides in the Meadowdale area and around Puget Sound. Mitigation for such slides include proper handling and discharge of surface storm water, reduction in ground water levels, and trimming or removal of large trees in the potential ' slide zone. We understand that since the 1996 and 1997 events, City improvements to surface water management of the right-of-ways above the slope to the east have been implemented, including installation of street drainage berms, catch basins, and prevention of storm water ' discharges onto or near the slope. These improvements will reduce the potential for saturation ' August 1, 2008 ASSOCIATED EARTH SCIENCES, INC. JDHAb - KE080287A2 - Projects 1200802871KEI WP Page 10 ' Subsurface Exploration, Geologic Hazard, and Hammond Residence Addition Preliminary Geotechnical Engineering Report Edmonds Washington Geologic Hazards and Mitigations 1 1 F of the colluvial soils and the contribution from upgradient surface water infiltration to ground water levels and seepages. The moderate risk of earth and debris flow damaging the dwelling was present for the existing structure and will not be increased by the proposed addition. However, additional debris -flow mitigation is recommended by extending the basement foundation wall 3 feet above the outside finish ground surface to create a catchment wall. Extension of the foundation wall would allow for debris -flow material to impact the back of the residence without buckling wood framing and damaging the structure. Deep-seated landslides risks at the project site would most likely be related to reactivation of the ancient landslide blocks estimated to have occurred thousands of years ago after the retreat of glacial ice and subsequent draining of glacial lakes. The large-scale lowering of regional ground water levels and continued erosion of the toe of the slopes by wave action resulted in unstable, oversteepened coastal bluff conditions. Mitigations for deep-seated slides at coastal bluffs include armoring of the base of the bluff to prevent wave erosion. The riprap embankment placed during the construction of the Burlington Northern Railroad tracks has provided protection from wave -action erosion. To our knowledge, no evidence of recent movement of the deep-seated slide planes has since . been documented. The 1980s drainage improvements in the 75`h Place West right-of-way and 1990s drainage improvements at the top of the steep slope have also reduced the potential for reactivation of the deep-seated slide planes. Mitigations for deep-seated landslides should include design and construction of a relatively rigid, grid -type shallow foundation system designed to mitigate differential foundation soil displacement. The primary purpose of the rigid grid foundation will be to create a monolithic foundation unit, which will be able to bridge potential, localized areas of settlement or resist soil creep movement. Specific foundation recommendations are discussed in the "Foundations" section of this letter. It should be noted that no amount of engineering and mitigation measures can eliminate the potential for earth movement. Some risks will always remain inherent for properties located on or adjacent to steep slopes. 6.0 SEISMIC HAZARDS AND RECOMMENDED MITIGATION ' Earthquakes occur in the Puget Lowland with great regularity. The vast majority of these events are small and are usually not felt by people. However, large earthquakes do occur as evidenced by the 1949, 7.2-magnitude event, the 2001, 6.8-magnitude event, and the 1965, ' 6.5-magnitude event. The 1949 earthquake appears to have been the largest in this region during recorded history and was centered in the Olympia area. Evaluation of earthquake return rates indicates that an earthquake of the magnitude between 5.5 and 6.0 is likely within ' a given 20- to 40-year period. ' August 1, 2008 ASSOCIATED EARTH SCIENCES, INC. JDH/tb - KE080287A2 - Projects1200802871KEMP Page 11 1 Subsurface Exploration, Geologic Hazard, and Hammond Residence Addition Preliminary Geotechnical Engineering Report Edmonds, Washington Geologic Hazards and Mitigations tGenerally, there are four types of potential geologic hazards associated with large seismic events: 1) surficial ground rupture; 2) seismically induced landslides; 3) liquefaction; and 4) ' ground motion. The potential for each of these hazards to adversely impact the proposed project is discussed below. ' 6.1 Surficial Ground Rupture Generally, the largest earthquakes that have occurred in the Puget Sound area are subcrustal ' events with epicenters ranging from 50 to 70 kilometers in depth. The 1949 and 2001 Olympia earthquakes are good examples of this type of seismic activity. Although the energy from deep subcrustal earthquakes does propagate up to the ground surface, actual surficial faulting and earth rupture features are rare. However, loose, wet soils may liquefy, move laterally, landslide, or otherwise settle or move, causing cracks and ruptures in the surficial soils during earthquakes. These types of damages are not related to actual fault rupture but are a result of ' ground shaking and liquefaction (see below). To our knowledge, no surficial faulting or earth rupture has been documented to date in the Lacey area. Therefore, it is our opinion, based on ' the existing geologic data, that the risk of surface rupture impacting the proposed project is low. ' 6.2 Seismically Induced Landslides The project site is located in the North Edmonds Earth Subsidence and Landslide Hazard Area, ' of which the risks of landslides have been discussed most recently in the 2007 Landau report and are discussed above. In our opinion, the risks associated with the above -described hazards are low to moderate under static conditions. Ground accelerations associated with a strong ' earthquake may reactivate movement along the old slide planes and result in a higher potential for landslides and ground displacements. This risk was present for the existing home under which it was originally permitted. Further, the current proposed addition will extend approximately 40 feet beyond the existing southern footing and will be placed on the same level bench as the existing house. It is the opinion of AESI that the construction of the ' proposed addition will not increase the risk of seismic induced landslide. We recommend mitigating damage to the proposed improvements by design and construction of a relatively rigid, grid -type, shallow foundation system as described in the "Foundations" section of this ' letter. The resulting foundation system will serve primarily to mitigate damage to the structure during differential ground displacements. ' August 1, 2008 ASSOCIATED EARTH SCIENCES, INC. !DH/tb - KE080287A2 - Projects1200802871KEMP Page 12 ' Subsurface Exploration, Geologic Hazard, and Hammond Residence Addition Preliminary Geotechnical Engineering Report Edmonds, Washington Geologic Hazards and Mitigations ' 6.3 Liquefaction ' The encountered stratigraphy has a low potential for liquefaction due to its medium dense to dense state and lack of adverse ground water conditions. No mitigation of liquefaction hazards is warranted. 6.4 Ground Motion 11 LJI Based on the site stratigraphy and visual reconnaissance of the site, it is our opinion that any earthquake damage to the proposed structures when founded on suitable bearing strata would be caused by the intensity and acceleration associated with the event and not any of the above - discussed impacts. Structural design of buildings should follow 2006 International Building Code (IBC) standards using Site Class "D" as defined in Table 1615.1.1. The 2006 IBC seismic design parameters for short period (Ss) and 1-second period (Si) spectral acceleration values were determined by the latitude and longitude of the project site using the United States Geological Survey (USGS) National Seismic Hazard Mapping Project website (http://earthquake.usgs.gov/hazmaps/). Based on the more current 2002 data, the USGS website interpolated ground motions at the project site to be 1.24g and 0.44g for building periods of 0.2 and 1.0 seconds, respectively, with a 2 percent chance of exceedance in 50 years. 7.0 Erosion Hazard Mitigation To mitigate the erosion hazards and potential for off -site sediment transport, we would recommend the following: 1. All disturbed areas should be revegetated as soon as possible. If it is outside of the growing season, the disturbed areas should be covered with mulch, as recommended in the erosion control plan. Straw mulch provides the most cost-effective cover measure and can be made wind -resistant with the application of a tackifier after it is placed. 2. Surface runoff and discharge should be controlled during and following development. Uncontrolled discharge may promote erosion and sediment transport. Under no circumstances should concentrated discharges be allowed to flow over the top of steep slopes. 3. Soils that are to be reused around the site should be stored in such a manner as to reduce erosion from the stockpile. Protective measures may include, but are not limited to, covering with plastic sheeting, the use of low stockpiles in flat areas, or the August 1, 2008 ASSOCIATED EARTH SCIENCES, INC. JDHAb - KE080287A2 - Projects1200802871KEMP Page 13 1 ' Subsurface Exploration, Geologic Hazard, and Hammond Residence Addition Preliminary Geotechnical Engineering Report Edmonds, Washington Geologic Hazards and Mitigations use of straw bales/silt fences around pile perimeters. During the period between October 1" and March 31", these measures are required. ' It is our opinion that with the proper implementation of the TESC plans and by field -adjusting appropriate mitigation elements (BMPs) during construction the potential adverse impacts from erosion hazards on the project may be mitigated. h, 1 H 0 1 t August 1, 2008 ASSOCIATED EARTH SCIENCES, INC. JDH/tb - KE080287A2 - Projects1200802871KE1WP Page 14 L I if I Subsurface Exploration, Geologic Hazard, and Hammond Residence Addition Preliminary Geotechnical Engineering Report Edmonds, Washington Preliminary Design Recommendations III. PRELIMINARY DESIGN RECOMMENDATIONS 8.0 INTRODUCTION The existing single-family residence is located within the North Edmonds Earth Subsidence and Landslide Hazard Area. Therefore, the risks described above were already present for the existing structure. It is our understanding that the owner fully understands and accepts the risks of the landslide hazards as discussed in this report. We also understand that potential future owners will be aware of the risks associated with owning property in the North Edmonds Earth Subsidence and Landslide Hazard Area because such a notice is required on the property title. The purpose of our study was to assess these risks based on current, site -specific, slope and soil conditions and provide recommendations for minimizing and mitigating adverse impacts to the slope by the proposed improvements. Since the project chiefly involves adding an addition to the south end of the existing residence, it is our opinion that the overall impact to the stability of the slope will not be adversely affected provided our recommendations are followed. Furthermore, the improvements will result in a safer structure since the improvements will be constructed on a relatively rigid foundation system and built to current building codes. The following sections present our recommendations for design and construction of the proposed improvements. 9.0 SITE PREPARATION 9.1 Clearing and Stripping Site preparation of the planned building area should include removal of all trees, brush, debris, and any other deleterious materials. These unsuitable materials should be properly disposed of off -site. Additionally, any areas of existing fill and organic topsoil should be removed from footing and slab on grade areas until the underlying native medium dense to dense native sediments are exposed. Areas where loose suriicial soils exist due to grubbing operations should be considered as fill to the depth of disturbance and treated as subsequently recommended for structural fill placement. Any buried utilities should be removed or relocated if they are under the proposed building area. The resulting depressions should be backfilled with structural fill as discussed under the "Structural Fill" section of this report. August 1, 2008 ASSOCIATED EARTH SCIENCES, INC. !DH/tb - KE080287A2 - Projects1200802871KENP Page 15 Subsurface Exploration, Geologic Hazard, and Hammond Residence Addition Preliminary Geotechnical Engineering Report Edmonds, Washington Preliminary Design Recommendations After stripping and grubbing operations have been completed, we recommend that the soil exposed in the proposed foundation, driveway, and any other pavement areas be recompacted to a firm and unyielding conditions. Any soft or yielding areas identified during compaction should be overexcavated and backfilled with structural fill. 9.2 Temporary Cut Slopes In our opinion, stable construction slopes should be the responsibility of the contractor and should be determined during construction based on the local conditions encountered at that time. For planning purposes, we anticipate that temporary, unsupported cut slopes over 4 feet high made in the medium dense to dense, landslide sediments can be made at a maximum ' slope of 1.5H:1V (Horizontal: Vertical). As is typical with earthwork operations, some sloughing and raveling may occur and cut slopes may have to be adjusted in the field. If ground water seepage is encountered, the cut slopes should be further laid back at a shallower angle and/or temporarily shored. In addition, WISHA/OSHA regulations should be followed at all times. 9.3 Site Disturbance I I The site soils contain a high percentage of fine-grained material, which makes them moisture - sensitive and subject to disturbance when wet. The contractor must use care during site preparation and excavation operations so that the underlying soils are not softened. If disturbance occurs, the softened soils should be removed and the area brought to grade with structural fill. If crushed rock is considered for the access and staging areas, it should be underlain by stabilization fabric (such as Mirafi 50OX or approved equivalent) to reduce the potential of fine-grained materials pumping up through the rock and turning the area to mud. The fabric will also aid in supporting construction equipment, thus reducing the amount of crushed rock required. We recommend that at least 10 inches of rock be placed over the fabric; however, due to the variable nature of the near -surface soils and differences in wheel loads, this thickness may have to be adjusted by the contractor in the field. Crushed rock used for access and staging areas should be of at least 2-inch size. 10.0 STRUCTURAL FILL Although grading plans were not available to AESI at the time of this study, we anticipate that structural fill may be necessary to establish desired grades in some areas. All references to structural fill in this report refer to subgrade preparation, fill type, and placement and compaction of materials as discussed in this section. If a percentage of compaction is specified under another section of this report, the value given in that section should be used. August 1, 2008 ASSOCIATED EARTH SCIENCES, INC. JDH/tb - KE080287A2 - Projects1200802871KEMP Page 16 1 Subsurface Exploration, Geologic Hazard, and Hammond Residence Addition Preliminary Geotechnical Engineering Report Edmonds, Washington Preliminary Design Recommendations 10.1 Subgrade Compaction After overexcavation/stripping has been performed to the satisfactionof the geotechnical engineer/engineering geologist, the upper 12 inches of exposed ground should be recompacted to at least 90 percent of the modified Proctor maximum dry density using American Society for ' Testing and Materials (ASTM):D 1557 as the standard. If the subgrade contains too much moisture, suitable recompaction may be difficult or impossible to obtain and should probably not be attempted. In lieu of recompaction, the area to receive fill should be blanketed with washed rock or quarry spalls to act as a capillary break between the new fill and the wet subgrade. Where the exposed ground remains soft and further overexcavation is impractical, placement of an engineering stabilization fabric may be necessary to prevent contamination of the free -draining layer by silt migration from below. After recompaction of the exposed ground is tested and approved, or a free -draining rock is laid, fill be desired course structural may placed to attain grades. 1 10.2 Structural Fill Compaction Structural fill is defined as non -organic soil, acceptable to the geotechnical engineer, placed in maximum 8-inch loose lifts, with each lift being compacted to at least 95 percent of the modified Proctor maximum dry density using ASTM:D 1557 as the standard. The top of the compacted fill should extend horizontally a minimum distance of 3 feet beyond footings or pavement edges before sloping down at an angle no steeper than 211:1V. Fill slopes should either be overbuilt and trimmed back to final grade or surface -compacted to the specified density. 10.3 Moisture -Sensitive Fill Soils in which the amount of fine-grained material (smaller than No. 200 sieve) is greater than approximately 5 percent (measured on the minus No. 4 sieve size) should be considered moisture -sensitive. Use of moisture -sensitive soil in structural fills should be limited to favorable dry weather conditions. The on -site, landslide sediments are suitable for use as structural fill but generally contain significant amounts of silt and are considered moisture - sensitive. At the time of our exploration, portions of these soils exhibited moisture contents in excess of the optimum for achieving maximum compaction. These soils are described on the attached explorations logs as "very moist". Construction equipment traversing the site when the soils are very moist or wet can cause considerable disturbance. If fill is placed during wet weather or if proper compaction cannot be obtained, a select import material consisting of a clean, free -draining gravel and/or sand should be used. Free -draining fill consists of non - August 1, 2008 ASSOCIATED EARTH SCIENCES, INC. !DH/tb - KE080287A2 - Projects 120080287WE1WP Page 17 Subsurface Exploration, Geologic Hazard, and Hammond Residence Addition Preliminary Geotechnical Engineering Report Edmonds Washington Preliminary Design Recommendations organic soil with the amount of fine-grained material limited to 5 percent by weight when measured on the minus No. 4 sieve fraction. ' 10.4 Structural Fill Testing The contractor should note that any proposed fill soils must be evaluated by AESI prior to their use in fills. This would require that we have a sample of the material at least 3 business days in advance to perform a Proctor test and determine its field compaction standard. A representative from our firm should inspect the stripped subgrade and be present during placement of structural fill to observe the work and perform a representative number of in - place density tests. In this way, the adequacy of the earthwork may be evaluated as filling progresses and any problem areas may be corrected at that time. It is important to understand that taking random compaction tests on a part-time basis will not assure uniformity or acceptable performance of a fill. As such, we are available to aid the owner in developing a suitable monitoring and testing frequency. 11.0 FOUNDATIONS 11.1 Allowable Soil Bearing Pressure Due to the variations in old landslide soils present at the anticipated bottom of footing elevations, we recommend that all new footings bear on a minimum, 2-foot-thick layer of structural fill. The width of the structural fill pad should be 2 feet wider than the width of the footing. Structural fill type, placement, and compaction recommendations are provided in the "Structural Fill" section of this letter. The existing fill soils must be removed under new foundations or overexcavated and recompacted as structural fill if moisture conditions allow. All organics, debris, and soft/loosened soil must be removed from the footing areas prior to placement of structural fill, and be confirmed by a representative from AESI. During wet weather, it is highly recommended that footing subgrades be protected from disturbance with several inches of compacted crushed rock. Continuous and column pad spread footings may be used for building support when founded on the approved 2-foot-thick layer of structural fill discussed above. Column pad footings should be structurally tied together in two directions in a grid -type formation to mitigate excessive ' ground displacements. The foundation system should be designed to span a loss of support of 10 feet. The owner should be aware that the primary purpose of tying together foundation elements is to mitigate or lessen damage to the structure due to potential soil displacements, as 1 discussed previously. We recommend that a maximum allowable foundation soil bearing August 1, 2008 ASSOCIATED EARTH SCIENCES, INC. JDH/tb - KE080287A2 - Projects1200802871KEMP Page 18 ' Subsurface Exploration, Geologic Hazard, and Hammond Residence Addition Preliminary Geotechnical Engineering Report Edmonds, Washington Preliminary Design Recommendations tpressure of 2,000 pounds per square foot (psf) be utilized for design purposes, including both dead and live loads, for footing subgrades prepared as described herein. An increase of one- third may be used for short-term wind or seismic loading. It should be noted that the area bounded by lines extending downward at 111:1V from any t footing must not intersect another footing. In addition, a 1.5H A V line extending down from any footing must not daylight because sloughing or raveling may eventually undermine the footing. Thus, footings should not be placed near the edge of steps or cuts in the bearing soils unless adequately embedded. 11.2 Footing Depths 1 tins for the proposed building should be buried a minimum of 18 inches into the Perimeter footings p p g ' surrounding soil for frost protection. No minimum burial depth is required for interior footings; however, all footings must penetrate to the prescribed stratum, and no footings should be founded in or above loose, organic, or existing fill soils. At the location of exploration pits 1 and 2, located in the area of the proposed addition, sediments suitable for foundation support were encountered at a depth of approximately 1 to 3.5 feet below the existing ground surface. 1 11.3 Footing Subgrade Bearing Verification Disturbed soil not removed from footing excavations prior to footing placement could result in increased settlements. All footing areas should be inspected by AESI prior to placing concrete to verify that the design bearing capacity of the soil has been attained and that construction conforms to the recommendations contained in this report. Such inspections may be required by the City. Perimeter footing drains should be provided as discussed under the section on "Drainage Considerations." 11.4 Foundation Drainage ' Perimeter footing drains should be provided as discussed under the section on "Drainage Considerations." 12.0 LATERAL WALL PRESSURES All backfill behind walls or around foundations should be placed following our recommendations for structural fill and as described in this section of the report. Horizontally backfilled walls, which are free to yield laterally at least 0.1 percent of their height, may be August 1, 2008 ASSOCIATED EARTH SCIENCES, INC. JDH/tb - KE080287A2 - Projects 1200802871KEI WP Page 19 Subsurface Exploration, Geologic Hazard, and Hammond Residence Addition Preliminary Geotechnical Engineering Report Edmonds Washington Preliminary Design Recommendations rdesigned using an equivalent fluid equal to 35 pounds per cubic foot (pcf). Fully restrained, horizontally backfilled, rigid walls that cannot yield should be designed for an equivalent fluid of 50 pcf. Walls that retain sloping backfill at a maximum angle of 2H:1V should be designed for 55 pcf for yielding conditions and 75 pcf for restrained conditions. If parking areas or driveways are adjacent to walls, a surcharge equivalent to 2 feet of soil should be added to the wall height in determining lateral design forces. Due to the potential for landslide soils to rest against the back of foundation stem walls, the east stem wall should be designed to resist at least 3 feet of soil pressure above the outside finish ground elevation. 12.1 Wall Backfill u P r� 1 LI u Ll The lateral pressures presented above are based on the conditions of a uniform backfill consisting of either the on -site glacial sediments or imported sand and gravel compacted to 90 to 92 percent of ASTM:D 1557. A higher degree of compaction is not recommended, as this will increase the pressure acting on the walls. A lower compaction may result in unacceptable settlement behind the walls. Thus, the compaction level is critical and must be tested by our firm during placement. The recommended compaction of 90 to 92 percent of ASTM:D 1557 applies to any structural fill placed behind the wall. within a distance equal to the wall height and up to the elevation of the top of the wall. In addition, only hand -operated or walk -behind compaction equipment should be used within 5 feet of the walls to prevent excessive surcharge loads from heavy equipment. Structural fill used to construct slopes above retaining walls should be compacted to at least 95 percent of ASTM:D 1557 if the fill is placed above the elevation of the top of the wall. Surcharges from adjacent footings, heavy construction equipment, or sloping ground must be added to the above recommended lateral pressures. Footing drains should be provided for all retaining walls, as discussed under the section on "Drainage Considerations." 12.2 Wall Drainage It is imperative that proper drainage be provided so that hydrostatic pressures do not develop against the walls. This would involve installation of a minimum 1-foot-wide blanket drain extending to within 1 foot of the top of wall using imported, washed gravel against the walls. The blanket drain and wall backfill should be capped with 1 foot of relatively impermeable soils that are sloped away from the walls to prevent surface water intrusion directly into the drain system. August 1, 2008 ASSOCIATED EARTH SCIENCES, INC. JDH1tb - KE080287A2 - Projects1200802871KEMP Page 20 Subsurface Exploration, Geologic Hazard, and Hammond Residence Addition Preliminary Geotechnical Engineering Report Edmonds, Washington Preliminary Design Recommendations ' 12.3 Passive Resistance and Friction Factor ' Lateral loads can be resisted by friction between the foundation and the natural, medium dense to dense glacial sediments or supporting structural fill soils, or by passive earth pressure acting on the buried portions of the foundations. The foundations must be backfilled with compacted structural fill to achieve the passive resistance provided below. We recommend the following design parameters. • Passive equivalent fluid = 250 pcf • Coefficient of friction = 0.30 The above values are allowable and include a factor of safety of at least 2.0. 13.0 FLOOR SUPPORT Slab -on -grade floors may be constructed on a minimum 12-inch-thick layer of approved structural fill compacted to a firm and unyielding condition. If moisture intrusion through slab -on -grade floors is to be limited, the floors should be constructed atop a capillary break consisting of a minimum thickness of 4 inches of washed pea gravel or 5/8-inch clean crushed rock (no fines). The pea gravel should be overlain by a 10- ' mil (minimum thickness) plastic vapor retarder. 1 14.0 DRAINAGE CONSIDERATIONS The natural glacial sediments encountered in our explorations generally contained significant amounts of silt and are considered to be highly moisture sensitive. Traffic from vehicles, construction equipment, and even foot traffic across these sediments when they are very moist ' or wet will result in disturbance of the otherwise firm stratum. Therefore, prior to site work and construction, the contractor should be prepared to provide drainage and subgrade protection, as necessary. 14.1 Wall/Foundation Drains ' All retaining and perimeter footing walls should be provided with a drain at the footing elevation. The drains should consist of rigid, perforated, polyvinyl chloride (PVC) pipe surrounded by washed pea gravel. The level of the perforations in the pipe should be set approximately 2 inches below the bottom of the footing, and the drains should be constructed August 1, 2008 ASSOCIATED EARTH SCIENCES, INC. JDHltb - KE080287A2 - Projects1200802871KEMP Page 21 77 Lj L7 Subsurface Exploration, Geologic Hazard, and Hammond Residence Addition Preliminary Geotechnical Engineering Report Edmonds, Washington Preliminary Design Recommendations with sufficient gradient to allow gravity discharge away from the building. All retaining walls should be lined with a minimum, 12-inch-thick, washed gravel blanket provided to within 1 foot of finish grade, and which ties into the footing drain. Roof and surface runoff should not discharge into the footing drain system, but should be handled by a separate, rigid, tightline drain. ' Exterior grades adjacent to walls should be sloped downward away from the structure to achieve surface drainage. Final exterior grades should promote free and positive drainage 1 away from the building at all times. Water must not be allowed to pond or to collect adjacent to the foundation or within the immediate building area. It is recommended that a gradient of at least 3 percent for a minimum distance of 10 feet from the building perimeter be provided, ' except in paved locations. In paved locations, a minimum gradient of 1 percent should be provided unless provisions are included for collection and disposal of surface water adjacent to ' the structure. Additionally, pavement subgrades should be crowned to provide drainage toward catch basins and pavement edges. 14.2 Utility Connections Due to the potential for differential soil displacement at the project site, we recommend the contractor install flexible connections between all utilities and the proposed residential addition. The connections should allow up to 6 inches of ground movement. t15.0 PROJECT DESIGN AND CONSTRUCTION MONITORING 1 We are available to provide additional geotechnical consultation as the project design develops and possibly changes from that upon which this report is based. If significant changes in grading are made, we recommend that AESI perform a geotechnical review of the plans prior tto final design completion. In this way, our earthwork and foundation recommendations may be properly interpreted and implemented in the design. 1-1 We are also available to provide geotechnical engineering and monitoring services during construction. The integrity of the foundations depends on proper site preparation and construction procedures. In addition, engineering decisions may have to be made in the field in the event that variations in subsurface conditions become apparent. Construction monitoring services are not part of this current scope of work. If these services are desired, please let us know and we will prepare a proposal. August 1, 2008 ASSOCIATED EARTH SCIENCES, INC. JDH/tb - KE080287A2 - Projects 1200802871KEI WP Page 22 P ' Subsurface Exploration, Geologic Hazard, and Hammond Residence Addition Preliminary Geotechnical Engineering Report Edmonds Washington Preliminary Design Recommendations ' We have enjoyed working with you on this study and are confident that these recommendations will aid in the successful completion of your project. If you should have any questions, or ' require further assistance, please do not hesitate to call. Sincerely, ' ASSOCIATED EARTH SCIENCES, INC. Kirkland, Washington 1 1 ' C Jon 15. Hansen Senior Staff Geologist. l I 1 Attachments: Figure 1: Vicinity Map Figure 2: Site and Exploration Plan Figure 3: Schematic Cross Section A -A' Appendix: Exploration Logs �///erg Aaron McMichael, P.E. Associate Geotechnical Engineer August 1, 2008 ASSOCIATED EARTH SCIENCES, INC. !DH/tb - KE080287A2 - Projects1200802871KEMP Page 23 1� z 0 � z 00 w Z C.) = z U) w < ui z w z > z 0 02 E a E w HSVM 901LZ 31VO ON J.03fO21d N0Woav 31ON30IS3H GN0WWVH ofm MS z aanolj NVId NOIIVHOIdY3 (INV dllS oui'saamp mug paippossV � yu�'saowag oBewoaO agped :�ua�a;a�{ � oa of o _ 1�1 I I \ D I 77 i 'du IId NOLLVMO,dX3 (! _ d0 NOUV301 i i (' 31VWIX021ddV -------------- i I .} 1 v t/ 7- I 101 N�17y r I-17�vi `ONINIVi3a L 1 l3AHavl i ` 1 I 1freH � / b I ;o 9NrdO8 aNVHi ! I O d0 NOLLVOOII I } o 31VWIXO2iddV: IV I ' ONOd— I �. I L•! �. I I kVM3AINCI ilVHdsV r 1 � \L } i I I I iy 1 I 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 CEO t0 O N O m 0000 Q OJ7L OZL OM 08 m og H w w 11 �Z w O U Z QUJ OZ C9 H w Z J O Q N Q I I 02 > 0 0 0 0 0 0 0 0 0 cn �n Ili �2 o am o (-OBA) N011VA 19 6mpvonoeS LOZO90 \ UOnIPPV saa P Cl) cO Q a' n OV W o (7 Q o W Y O Z F— U w O w IL Q Q Z Z O O�- 00 U W w Z U S 6 w Q U) 2 � O w vi Cr 0� 0 U o p C) O (� w O < J = 0 V u t &� u cc4�C W TI cz V; iowweH sPO LEON 1 APPENDIX I Ll 11 I I LOG OF EXPLORATION PIT NO. EP-1 11 J 11 t This log is part of the report prepared by Associated Earth Sciences, Inc. (AESI) for the named project and should be together that report for complete interpretation. This summary applies only to the location of this trench at the read with time of excavation. Subsurface conditions may change at this location with the passage of time. The data presented are p a simplfication of actual conditions encountered. DESCRIPTION Sod Fill 1 Medium dense to dense, moist, gray, silty fine to medium SAND, few gravel, trace organic debris. 2 3 Topsoil Medium dense, moist, dark brown, silty SAND, few gravel, trace to few organics. 4 Old Landslide Block Medium dense to dense, moist (light gray to gray, silty fine to medium SAND), few to little gravel, 5 trace cobbles (slightly mottled from 3.5' to 5'). 6 Blocky during excavation. 7 8 Bottom of exploration pit at depth 7.5 feet No caving or seepage noted. 9 10 11 12 13 14 15 16 17 18 19 Hammond Residence Addition Edmonds, WA Associated Earth Sciences, Inc. Logged by: JDH Approved by: NE r. x Project No. KE080287A 6/13/08 LOG OF EXPLORATION PIT NO. EP-2 L C� �I L� r 1 This log is part of the report prepared by Associated Earth Sciences, Inc. (AESI) for the named project and should be read together with that report for complete interpretation. This summary applies only to the location of this trench at the a time of excavation. Subsurface conditions may change at this location with the passage of time. The data presented are o a simplfication of actual conditions encountered. DESCRIPTION Topsoil/Fill Loose to medium dense, moist, dark brown to dark gray, silty SAND, little gravel, trace organics 1 (sticks and roots). Old Landslide Block 2 Medium dense to dense, moist, gray, silty fine to medium SAND, little gravel (slightly mottled from 1' to 3.5'). 3 4 Blocky during excavation. 5 6 7 Bottom of exploration pit at depth 7 feet 8 No caving or seepage observed. 9 10 11 12 13 14 15 16 17 18 19 co N Hammond Residence Addition Edmonds, WA Associated Earth Sciences, Inc. Logged by: JDH Project No. KE080287A cY f Approved by:� « : 6113108 a f- U Y LOG OF EXPLORATION PIT NO. 1-113-3 fl 1 1 1 Ji r] J x L This log is part of the report Prepared ly Associated Earth Sciences, Inc. (AESI) for the named project and should be together with that report for complete interpretation. This summary applies only to the location of this trench at the C read time of excavation. Subsurface conditions may change at this location with the passage of time. The data presented are o a simplfication of actual conditions encountered. DESCRIPTION Colluvium Loose, moist, gray, silty SAND, few to little gravel, trace organic debris. 1 2 Old Landslide Block 3 Medium dense to dense, moist, gray, silty fine to medium SAND, few to little gravel. Bottom of exploration pit at depth 3 feet 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 Hammond Residence Addition fV Edmonds, WA a Associated Earth Sciences, Inc. o Logged by: JDH Project No. KE080287A Wiz; a Approved by: 6/13/08 U Y LOG OF EXPLORATION PIT NO. HB-4 1 1 1 1 1 1 1 This log is part of the report prepared by Associated Earth Sciences, Inc. (AESI) for the named project and should be interpretation. This location w m read together with that report for complete summary applies only to the of this trench at the time of excavation. Subsurface conditions may change at this location with the passage of time. The data presented are o a simplfication of actual conditions encountered. DESCRIPTION Colluvium Loose, moist, gray to dark gray, silty SAND, few gravel, trace organics, trace cobbles. 1 2 Old Landslide Block Medium dense to dense, moist, gray, silty fine to medium SAND, few to little gravel. 3 Bottom of exploration pit at depth 2.5 feet 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 N Hammond Residence Addition N Edmonds, WA 0. Associated Earth Sciences, Inc. Project No. KE080287A g Logged by: JDH Approved by: F«.� : �' 6/13/08 EL ` Y 6vcf-1- 11 RETURN ADDRESS: City of Edmonds, City Clerk 121 5th Avenue North Edmonds, WA 98020 4- &6. wa. �oo9p��pp76� COVENANT OF NOTIFICATION AND INDEMNIFICATION/HOLD HARMLESS Reference #:_� Grantor(s): (1)Q-11IQI S Additional on pg. Grantee(s): City of Edmonds Legal Description (abbreviated): Sec Twn ol-97J Rug 4 OR Lot Block PlatCb(tlddle Assessor's Tax Parcel EN(s): (1) (2) 0026h Assessor's Tax Parcel 1D# not yet assigned CITY OF EDMONDS APPROVED FOR RECORDING BY; 0 DATE�� PAGE _L OF 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: APPR V D FOR RECORDING: BY: DATE: PAGE OF 1. Description of Subject Property. This covenant of notification and indemnification/hold harmless relates to a tract of land at the street address of ISbQS -740*A (� (insert street address), Edmonds Snohomish County, Washington and legally described as: (PER STATUTORY WARRANTY DEED RECORDING NO. 200102230189) ALL THAT PORTION OF TRACT 24, PLAT OF MEADOWDALE BEACH, ACCORDING TO THE PLAT THEREOF RECORDED IN VOLUME 5 OF PLATS, PAGE 38, IN SNOHOMISH COUNTY, WASHINGTON, DESCRIBED AS FOLLOWS. BEGINNING AT THE SOUTHWEST CORNER OF THAT PORTION OF TRACT 24 LYING EAST OF COUNTY ROAD, THENCE IN A NORTHERLY DIRECTION ALONG THE EASTERLY MARGIN OF SAID ROAD 142 FEET TO THE POINT OF BEGINNING, THENCE CONTINUING NORTHERLY ALONG EAST MARGIN OF COUNTY ROAD 122 FEET, THENCE EASTERLY PARALLEL TO SOUTH BOUNDARY OF TRACT 24 120 FEET; THENCE SOUTHERLY PARALLEL TO THE COUNTY ROAD 122 FEET, THENCE WESTERLY PARALLEL TO SOUTH BOUNDARY OF TRACT 24 120 FEET TO THE POINT OF BEGINNING 2. Notification and Covenant of Notification. The above referenced site (hereinafter "subject site") lies 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 (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 EA�EDR REDATOF 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 employees arising 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 APPROVED FOR RECO G: 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. JAPP R�R RETECO-F��[N�: BY: DA: PAGE_ OF DONE this day of , 199_. OWNER(S) By: By: By STATE OF WASHINGTON ) ) ss: COUNTY OF K11. & ) I certify that I know or have satisfactory evidence than t4 Hlk A-Nk0K0 signed this instrument and acknowledged it to be (his/her) free and voluntary act for the purposes mentioned in thic instrument DATED this 124,\d day of So6jajjjjCj �- NOTAR P C � °:z� v =0 My co ission expires: "k 9100 2� L:\TEMP\BUILDING\MEADOW\COVENANT • APPR VED FOR RECORDING: BY: DATE: PAG OF STATE OF WASHINGTON ) ) ss: COUNTY OF Y-JK& ) I certify that I know or have satisfactory evidence that "1 "5 HAMA &g-D signed this instrument and acknowledged it to be (his/her) free and voluntary act for the purposes mentioned in this instrument. DATED this 1W day of ;Ater �= O .• U N B L!G 6-09 W JCS �� L:\TEMP\BUII.DING\MEADOW\COV ENANr NOTARY/PUBLIC My co ission expires: 0 -PETERSON )TREHLE I /1ARTINSON, INC. CONSULTING ENGINEERS January 14, 2009 Steve Barnes Cornerstone Architectural Group RE: Hammond Residence 156th 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 Vice President EXPIRES 0b/1 7/ D q_ __I DECEIVED FEB - 6 2009 DEVELOPMENT SERVICES CTR. CITY OF EDMONDS 2200 SIXTH AVENUE, SUITE 601 PHONE 206-622-4580 SEATTLE WASHINGTON 98121 FAX 206-622-0422 W011MR114 PETERSON )TREHLE I /JARTINSON, INC. CONSULTING ENGINEERS January 14, 2009 Steve Barnes Cornerstone Architectural Group RE: Hammond Residence 156th Street SW Edmonds, Washington Steve: Structural Engineer declaration: RESUB MAY 0 8 2009 ENT 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. The soils report describes geologic hazards which go beyond the scope of structural engineering associated with this project. The building has been designed to minimize hazards and potential problems from earth movement to protect the structure and it's inhabitants as described in the geotechnical report. Some risks will always remain inherent for properties located on or adjacent to steep slopes. Sincerely, PETERSON STREHLE MARTINSON, INC. M. David Stubbs, PE, SE Vice President ........ sl: 33253 ' � r ANAL G�{� r w P EXPIRES ��J117� I STREET FILE 2200 SIXTH AVENUE, SUITE 601 PHONE 206-622-4580 SEATTLE WASHINGTON 98121 FAX 206-622-0422 6161 NE 175th Street, Suite 101 II Cornerstone Kenmore, Washington 0 _ 206.682.5.500000 A R C H I T E C T U R A L G R O U P cornerstonearch.com January 15, 2009 City of Edmonds Re: Hammond 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. Sincerely, Steve Barnes RECEIVED FEB - 6.2009 DEVELOPMENT SERVICES CTR. CITY OF FRIUlpNnc d �, January 30, 2009 City of Edmonds Re: Hammond 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 or 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, 6,,► I `>81 S se- � ✓ �� C? �� E✓u � ��I �$00� �xprr,67s. 0 7 - 0 Z • CU RECEIVED FEB - 6 2009 DINEW MWSERVICES CM CITY OF EDMONDS 0 TET FILE • N U Z w LU r� ' . go Cornerstone ARCH ITECTURAL GROUP April 8, 2009 City of Edmonds Re: Hammond Residence To Whom It May Concern: Applicant/Owner liability & landsclide acknowledgement: 6161 NE 175th Street, Suite 101 Kenmore, Washington 98028 206.682.5000 cornerstonearch.com 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, Steve Barnes Architect U6 APR - 2009 DUI? DING DEPARTMENT CRY STREET FILE Cornerstone A R C H I T E C T U R A L G R O U P April 8, 2009 City of Edmonds Re: Hammond Residence To Whom It May Concern: Applicant/Owner liability & landsclide acknowledgement: 6161 NE 175th Street, Suite 101 Kenmore, Washington 98028 206.682.5000 corn erstonearch.com The accuracy of permit submittal information is warranted by the applicant and relieves the City and its 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, Steve Barnes Architect 3 APR - 2009 SUI! DING DEPA RM-1 NT I � W W j Z 1- � J y 4) Q R' Uj Uj Z Y � K N Z W o N o a Z o a r � y ~ J j Z N W H Q fn J W O Z n g o • to W W F W a )n Z N Z 3 i O ZUj z Y 0 W j2 ~ F- 3 D X ~ Z Q LU U 3: • • • fn Z _J ~ W w�U. z O .o 3 a co Z x 5 LL, W p Q Z a U. N p W D m J W y N • ItIfILDIN� �� ;MNp Jun .2- 1997 CONSULTING ENGINEERS PROJECT NUMBER 2234 25 May 1997 page 1 of 3 pages CLIENT Alice Andahl 7516 Eaglefield Drive Arlington, Washington 98223 REFERENCE : Andahl house located at 15605 75"' Place W, Meadowdale SUBJECT : Investigation of slide and garage damage. INTRODUCTION The purpose of this report is to present the results of a geotechnical investigation of the slide and garage damage located at 15605 75 h Place West, Meadowdale, Edmonds. The investigation and report were authorized on 10 May 1997 by Alice Andahl, owner, during a conversation with Dale C. Hemphill of HEMPHILL CONSULTING ENGINEERS. INVESTIGATION HEMPHILL observed that the steep slope behind and north of the house had slid and collapsed the garage, damaging the contents including a car and boat. There was no evidence of damage to the house. The slide occurred on an unimproved extension of 156"' Street. HEMPHILL climbed the slope and observed and tested the exposed soils, and determined that the remaining soils are hard and/or very dense and capable of standing at the steep slope. The soils that slid had become loosened by the weathering processes, which include wetting and drying, freezing and thawing, root action, direct rainfall, groundwater seepage, and uncontrolled or concentrated surface stormwater runoff. The most damaging to strong deeper soils on steep slopes is root action, usually from trees and mostly during heavy winds. The already loosened soils usually slide during or after a heavy rainfall where the excess water has increased the weight and softened the soils. 4041 WEST LAKE SAMMAMISH PARKWAY SOUTHEAST • BELLEVUE • WASHINGTON • 98008 • 206 644 1080 C] • PROJECT NUMBER 2234 25 May 1997 The excess water includes uncontrolled and/or concentrated surface runoff from the property above the slope. The excessive surface runoff often erodes the weakened soils, causing a flow slide that can be the most damaging to downhill properties because of the velocities achieved, and the distances that flow slides can travel. A neighbor claimed to have observed a pipe at the upper south end of the page 2 of 3 pages slide surface to be leaking and finally burst to release a large volume of water onto the slope prior to the slide. The source and volume of the water were not determined by HEMPHILL. The pipe has since been repaired. HEMPHILL observed three pipes at that location, two of which were not properly anchored to prevent future failures. The third pipe conducts water to an open catch basin at the base of the slope behind the Andahl house. CONCLUSIONS and RECOMMENDATIONS HEMPHILL concludes that the slide was composed of the upper weathered soils that had been saturated and eroded by an unprecedented natural occurrence, and by a broken pipe that was not properly installed. The remaining soils are strong and capable of standing until the upper surface again softens due to the weathering processes, which could be many years. The soils on adjacent slopes will probably slide before that occurrence. The soils on adjacent slopes exist at similar angles and possibly the same amount of weathering, therefore the broken pipe could have been the major factor causing the failure. Natural runoff from the upper property is directed toward the undisturbed slope north of the slide. Other portions of the slope that did not slide have survived two unprecedented natural occurrences; the heavy rainfall of a 5 day period that included a 100 year rainfall on 8 February 1996, and the combination snowmelt/rainfall on 31 December 1996. Therefore the exposed surface of the slide area, and the adjacent slopes, are stable at least until the next unprecedented occurrence, or the failure of the pipes or other uncontrolled condition at the top of the slope. ]ENZIM XPREURL u �1 PROJECT NUMBER 2234 25 May 1997 HEMPHILL concludes that the slide debris does not retain any portion of the slope, and therefore can be removed from the lower areas around the north and east sides of the house. The damaged garage can be removed and replaced, and damage Dale C. Hemphill P.E. Registered Engineer No. 14777 State of Washington page 3 of 3 pages to the house, if any, can be repaired. There is no structural damage to the house, therefore the house can be occupied. There is no danger of damage from the existing debris, or slides from the upper slopes until another unprecedented occurrence. I� v� 0 WAS �1 14777 o FcisrER`�° law �SfONALENG EXPIRES.17 FEBRUARY 1998 E-Ir-DRIl-DRIP, r4 o iu it Z F > 26; 0 Z- LU LLI Na x z 2 I a o 1 1 0 a 0*01 cf x Ee G 6a T LLJ LU C, 7M - — — — — — — — — C) — — — — < m -2 < E. H all as cn z of i — � r�t V ---- —0sum— I Hgg z! A MHO — MHO , , _4,-MHO- MPG Mpa fl�" Avmavotj IIVP.,ISV b, ji Lilz S' — - — s� — F- " IS. —(O-N'HV38 do SISVG) M.£9,6£.00N Nvo8 AiNnoo) 41 7d i-Lgz z8?= Nf zv mm 0 *0. 83HSVM/M lPVN)ld CNnoj 5a: m MHO —0 71 0�'oo-zvt IQ Es. 16- 11 T -z U4 wz. 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