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CANOD.pdfCity of Edmonds Critical Area Notice of Decision Applicant: ",A�C.°/r1 Property Owner: Critical Area File Permit Number: Site Location: Parcel Number: o-1 3 00 Project Description: Conditional Waiver. No critical area report is required for the project described above 1. There will be no alteration of a,Critical Area or its required buffer. '2 2, The proposal is an allowed activity pursuant to ECDC 23.40.220, 23.50.220, and/or 23.80.040. 3. The proposal is exempt pursuant to ECDC 23.40.230. Erosion Hazard. Project is within erosion hazard area. Applicant must prepare an erosion and sediment control plan in compliance with ECDC 18.30. A -Critical Area Report Required. The proposed project is within a critical area and/or a critical area buffer and a critical area report is required. A critical area report has been submitted and evaluated for compliance with the following criteria pursuant to ECDC 23.40.160: 1.'" The proposal minimizes the impact on critical areas in accordance with ECDC 23.40,120, Mitigation sequencing; 2. The proposal does not pose an unreasonable threat to the public health, safety, or welfare on or off the development proposal site; 3. The proposal is consistent with the general purposes of this title and the public interest; 4. Any alterations permitted to the critical area are mitigated in accordance with ECDC 23 A0.1 10, Mitigation requirements. 5. The proposal protects the critical area functions and values consistent with the best available science and results in no net loss of critical functions and values; and The proposal is consistent with other applicable regulations and standards. V E] Unfavorable Critical Area Decision. The proposed project is not exempt or does not adequately mitigate its impacts on critical areas and/or does not comply with the criteria in ECDC 23.40,160 and the provisions of the City of Edmonds critical area regulations. See attached findings of noncompliance. Favorable Critical Area Decision. The proposed project as described above and as shown on the attached site plan meets or is exempt from the criteria in ECDC 23.40.160, Review Criteria, arid complies with the applicable provisions of the City of Edmonds critical area regulations, Any subsequent changes to the proposal shall void this decision pending re -review of the proposal. Conditions. Critical Area specific condition(s) have been applied to the permit number referenced above, See referenced permit number for specific condition(s). /P 5, vc Reviewer Signature Date Appeals: Any decision to approve, condition, or deny a development proposal or other activity based on the requirements of critical area regulations may be appealed according to, and as part of, the appeal procedure, if any, for the permit or approval involved. Revised 12/16/2.010 -l"l ,x ' ip:u GEOTECHNICAL ENGINEERING STUD) PROPOSED SINGLE-FAMILY RESIDENCES 1035 MAIN STREET EDMONDS, WASHINGTON ES -3380 1 0 5 IJ V, IA_ L", `6 GEOTECHNICAL ENGINEERING STUD) PROPOSED SINGLE-FAMILY RESIDENCES 1035 MAIN STREET EDMONDS, WASHINGTON ES -3380 1 0 5 p - Kyle R. Campbell, .;iiP.E. _ _ Principal PROPOSEDSINGLE-FAMILY RESIDENCES 1035 MAIN STREET EDMONDS, WASHINGTON Earth ' `• u t,i ,, I _ Northeast, Geolech,01col Repopt Geotechnical SepvIces Ape Peplopmed for Specific Pupposes, Persons and Projects Geotechnical engineers structure their services to meet the specific needs of their clients. A geotechnical engineering study conducted for a civil engi- neer may not fulfill the needs of a construction contractor or even another civil engineer. Because each geotechnical engineering study is unique, each geotechnical engineering report is unique, prepared solelyfor the client. No one except you should rely on your geotechnical engineering report without first conferring with the geotechnical engineer who prepared it. And no one — noteven you —should apply the report for any purpose or project except the one originally contemplated. Read a Full Repopt Serious problems have occurred because those relying on a geotechnical engineering report did not read it all. Do not rely on an executive summary Do not read selected elements only. eo echnical Engineering Heapt,1s Based on Unique Set Of PPolect-SpeCHPIC Factors Geotechnical engineers consider a number of unique, project -specific fac- tors when establishing the scope of a study. Typical factors include: the client's goals, objectives, and risk management preferences; the general nature of the structure involved, its size, and configuration; the location of the structure on the site; and other planned of existing site improvements, such as access roads, parking lots, and underground utilities, unless the geotechnical engineer who conducted the study specifically indicates oth- erwise, do not rely on a geotechnical engineering report that was: ® not prepared for you, ® not prepared for your project, ® not prepared for the specific site explored, or ® completed before important project changes were made. Typical changes that can erode the reliability of an existing geotechnical engineering report include those that affect: ® the function of the proposed structure, as when it's changed from a parking garage to an office building, or from a light industrial plant to a refrigerated warehouse, ® elevation, configuration, location, orientation, or weight of the proposed structure, ® composition of the design team, or ® project ownership. As a general rule, always inform your geotechnical engineer of project changes—even minor ones—and request an assessment of their impact. Geotechnical engineers cannot accept responsibility or liability for problems that occur because their reports do not consider developments of which they were not informed. Subsurface Conditions Can Change A geotechnical engineering report is based on conditions that existed at the time the study was performed. Do not rely on a geotechnical engineer- ing reportwhose adequacy may have been affected by: the passage of time; by man-made events, such as construction on or adjacent to the site; or by natural events, such as floods, earthquakes, or groundwater fluctua- tions. Always contact the geotechnical engineer before applying the report to determine if it is still reliable. A minor amount of additional testing or analysis could prevent major problems. Most Geotechnical Findings Are Professional Opinions Site exploration identifies subsurface conditions only at those points where subsurface tests are conducted or samples are taken. Geotechnical engi- neers review field and laboratory data and then apply their professional judgment to render an opinion about subsurface conditions throughout the site. Actual subsurface conditions may differ=sometimes significantly— from those indicated in your report, Retaining the geotechnical engineer who developed your report to provide construction observation is the most effective method of managing the risks associated with unanticipated conditions. Report's Recommendations ApeNot Final Do not overrely on the construction recommendations included in your report. Those recommendations are not final, because geotechnical engi- neers develop them principally from judgment and opinion. Geotechnical engineers can finalize their recommendations only by observing actual subsurface conditions revealed during construction. The geotechnical engineer who developed your report cannot assume responsibility or liability for the report's recommendations if that engineer does not perform construction observation. Geotechnical ineepin ort is Subject to Misintepppetation Other design team members' misinterpretation of geotechnical engineering reports has resulted in costly problems. Lower that risk by having your geo- technical engineer confer with appropriate members of the design team after submitting the report. Also retain your geotechnical engineer to review perti- nent elements of the design team's plans and specifications. Contractors can also misinterpret a geotechnical engineering report. Reduce that risk by having your geotechnical engineer participate in prebid and preconstruction conferences, and by providing construction observation. 0 Not Redpaw the Engineep's togs Geotechnical engineers prepare final boring and testing logs based upon their interpretation of field logs and laboratory data, To prevent errors or omissions, the logs included in a geotechnical engineering report should never be redrawn for inclusion in architectural or other design drawings. Only photographic or electronic reproduction is acceptable, but recognize that separating logs from the report can elevate rislc Give c p Complete opt an Guidance Some owners and design professionals mistakenly believe they can make contractors liable for unanticipated subsurface conditions by limiting what they provide for bid preparation, To help prevent costly problems, give con- tractors the complete geotechnical engineering report, butpreface it with a clearly written letter of transmittal. In that letter, advise contractors that the report was not prepared for purposes of bid development and that the report's accuracy is limited; encourage them to confer with the geotechnical engineer who prepared the report (a modest fee may be required) and/or to conduct additional study to obtain the specific types of information they need or prefer. A prebid conference can also be valuable. Be sure contrac- tors have sufficient time to perform additional, study. Only then might you be in a position to give contractors the best information available to you, while requiring them to at least share some of the financial responsibilities stemming from unanticipated conditions. Beall Responsibility Ppovislons Closely Some clients, design professionals, and contractors do not recognize that geotechnical engineering is far less exact than other engineering disci- plines. This lack of understanding has created,unrealistic expectations that have led to disappointments, claims, and disputes. To help reduce the risk of such outcomes, geotechnical engineers commonly include a variety of explanatory provisions in their reports. Sometimes labeled "limitations' many of these provisions indicate where geotechnical engineers' responsi- bilities begin and end, to help others recognize their own responsibilities and risks. Read these provisions closely. Ask questions. Your geotechnical engineer should respond fully and frankly, eoenuipon ental Concepns APO Not CovePed The equipment, techniques, and personnel used to perform a geoenviron- mental study differ significantly from those used to perform a geotechnical study. For that reason, a geotechnical engineering report does not usually relate any geoenvironmental findings, conclusions, or recommendations; e.g., about the likelihood of encountering underground storage tanks or regulated contaminants. Unanticipated environmental problems have led to numerous project failures. If you have not yet obtained your own geoen- vironmental information, ask your geotechnical consultant for risk man- agement guidance. Do not rely on an environmental report prepared for someone else. obtain Professional Assistance To Deal with Mold Diverse strategies can be applied during building design, construction, operation, and maintenance to prevent significant amounts of mold from growing on indoor surfaces. To be effective, all such strategies should be devised for the express purpose of mold prevention, integrated into a com- prehensive plan, and executed with diligent oversight by a professional mold prevention consultant. Because just a small amount of water or moisture can lead to the development of severe mold infestations, a num- ber of mold prevention strategies focus on keeping building surfaces dry. While groundwater, water infiltration, and similar issues may have been addressed as part of the geotechnical engineering study whose findings are conveyed irtthis report, the geotechnical engineer in charge of this project is not a mold prevention consultant; none of the services per- formed in connection with the geotechnical engineer's study were designed or conducted for the purpose of mold preven- tion. Proper implementation of the recommendations conveyed in this report will not of itself be sufficient to prevent mold from growing in or on the structure involved. Rely, on Your ASFE-Member Geotechucial Engineep fop Additional Assistance Membership in ASFE/The Best People on Earth exposes geotechnical engineers to a wide array of risk management techniques that can be of genuine benefit for everyone involved with a construction project. Confer with you ASFE-member geotechnical engineer for more information. 8811 Colesville Road/Suite G106, Silver Spring, MD 20910 Telephone: 301/565-2733 Facsimile: 301/589-2017 e-mail: info@asfe.org www.asfe.org Copyright 2004 by ASFE, Inc. Duplication, reproduction, or copying of this document, in whole or in part by any means whatsoever, is strictly prohibited, except with AWE'S specific written permission. Excerpting, quoting, or otherwise extracting wording from this document is permitted only with the express written permission ofASFE, and only for purposes of scholarly research or book review. only members of ASFE may use this document as a complement to oras an element of a geotechnical engineering report Any other firm, individual, or other entity that so uses this document without being an ASFE member could be committing negligent or intentional (fraudulent) misrepresentation. IIGER06045,OM June 23, 2014 ES -3380 Echelbarger Investments, LLC 4001 — 198t" Street southwest Lynnwood, Washington 98036 Attention: Mr. Todd Echelbarger Dear Mr. Echelbarger: -�Ear2 h; So1u i nts Earth Solutions NW LLC • Geotechnical Engineering • Construction Monitoring • Environmental Sciences Earth Solutions NW, LLC (ESNW) is pleased to present this report titled "Geotechnical Engineering Study, Proposed Single -Family Residences, 1035 Main Street, Edmonds, Washington". Based on the results of our study, construction of the proposed single-family residential structures at the subject site is feasible from a geotechnical standpoint. Based on the results of our study, the proposed residential structures can be supported on a conventional foundation system bearing on competent native soil, recompacted native soil, or structural fill. Competent soils suitable for support of foundations should be encountered at depths of about four to six feet below existing grades across the majority of the site. Slab -on - grade floors should be supported on dense native soil, re -compacted native soil, or structural fill. Where loose, organic or other unsuitable materials are encountered at or below the footing subgrade elevation, the material should be removed and replaced with structural fill, as necessary. This report provides a geologically hazardous areas assessment, and recommendations for loundation subgrade preparation, •. • and retaining wall design parameters, drainage, the suitability of the on �8ite soils for use as structural fill, and other. geotechnical recommendations. The opportunity to be of service to you is appreciated. If you have any questions regarding the content of this geotechnical engineering study, please call. Sincerely, Henry T. right, E.I.T. Staff En ineer '1805 - 136th Place N.E., Suite 201 • Bellevue, WA 98005 • (425) 449-4704 ® FAX (425) 449-4711 INTRODUCTION 1 General ......... .............. 1 ProiectDescription,;,........... ............ :......... :......... 2 SITE CON ®IT'INS ...,,..,.<................................................. . 2 . . Surface.......... ........ ....,,....,,............... ,.................. ..,............ 2 Subsurface.......... ....................................... . . .................... 2 Geologic Setting... . ............. .... .,. .... 3 Groundwater........:.. ...................... 3 GEOLOGICALLY HAZARDOUS AREAS ASSESSMENT, 3 Slope Reconnaissance Landslide z , Areas Analysis. ii Minimum Buffer and Building Setback General.....:......................,.,.....,,>.......>.,: "....,,........>,.....,... Site Pre aration and Earthwork,.,,,,,., .......... 5 6 Temporary Erosion Control.,........:., .:: ....::: ....::.............. 6 In -Situ Soils ................... I .......... ...............:.....<...>„ ,<.:;. 6 Structural Fill....................................................................... 6 Excavations and Slopes .......................... ..... 7 Foundations ...................... .........,........ 7 SeismicConsiderations........................................................ 6 Slab -on -Grade Floors. ..... ...... ... .... ......... 3 Retaininq Walls ................ ,........ ...;, :..,,. .;...,...>. 6 qra age. ... ,,.. .. _ ,.... _ ............. 9 Utilitv Trench Sup ort and 9 Pavement Sections........,...,.. ... ......................... ..,. 9 LIMITATIONS....,.,.. ............................,.. 10 Additional Services,_,,, ...............,.,....., ,.............;. 10 Earth Solutions NW, LLC ?#nt»±¥ F? Plate I Vicinity :»« ** Plate 2 BoringLocation Plan Retaining » Plate > Wall «<^Drainage Detail2 Plate 2«422+ #rv.'^ .. Footing Drain #f<V2 +ff?\»223 Appendix T Subsurface E<plo:vt*c #*§r« Logs ±+f±9kix ■ Laboratory Test ?e s t a Gram /?± Distribution Earth Solutions NW, LC W iff—OVIA-f 140y PROPOSED SINGLE-FAMILY RESIDENCES 1035 MAIN STREET EDMONDS, WASHINGTON A 4� X This geotechnical engineering study was prepared for the proposed single-family residential structures to be constructed at 1035 Main Street in Edmonds, Washington. To complete the scope of services detailed in our proposal PES -3380 dated May 5, 2014, we performed the following: Subsurface exploration and characterization of soil and groundwater conditions by advancing a boring adjacent to the toe of the steep slope to the north of the property; 0 Engineering analyses and recommendations for the proposed development, and; 0 Preparation of this report. il/ ro!mrol�ii.�lf!rol��l.�lilli�,111r,�HIIIIIingm Geologic Map of the Edmonds East and Part of the Edmonds West Quadrangle; Washington, prepared by James P. Minard, dated 1983; it Critical Areas Reconnaissance Report, Critical Areas File Number CRA20140021 an* CRA20140022, prepared by City of Edmonds; North Edmonds Earth Subsidence and Landslide Hazard Area Summary Repo prepared by Landau Associates, dated March 14, 2007, and; I Earth Solutions NW, LLC Echelbarger Investments, LLC June 23, 2014 Based on the site plan provided to us, the existing single-family residential structure and associated outbuildings will be demolished and two new single-family residential structures will be constructed. We anticipate grading activities will include cuts and fills to establish the planned building alignments. Based on the existing grades, we estimate cuts to establish building pad and foundation subgrade elevations will be on the order of up 10 to 12 feet. However, grading plans were not available at the time this report was prepared. Site improvements will also include underground utility installations. At the time this report was prepared, specific building load values were not available. However, we anticipate the proposed` residential structures will consist of relatively lightly loaded wood framing supported on conventional foundations. Based on our experience with similar developments, we estimate wall loads on the order of two kips per linear foot and slab -on -grade loading of 150 pounds per square foot (psf). If the above design assumptions are incorrect or change, ESNW should be contacted to review the recommendations in this report. ESNW should review the final design to verify the geotechnical recommendations provided in this report have been incorporated into the plans. The subject site located at 1035 Main Street in Edmonds, Washington, as illustrated on the Vicinity Map (Plate 1). The site consists of two residential tax parcels (Snohomish County parcel numbers 0434204003000 and 0434204002800) totaling approximately 0.28 acres of land area. The property is,currently developed with a single-family residence and associated improvements. The majority of the site is relatively level with a gentle west descending slope. Based on site observation and review of the referenced critical areas reconnaissance report, a south descending slope with a gradient in excess of 50 percent is located to the north of the site. Vegetation within the steep slope area consists of mature trees, saplings, and ivy groundcover. The subject site is bordered to the north, east, and west by residential structures and to the south by Main Street. The Boring Location Plan (Plate 2) illustrates the approximate limits and local topography of the property. • i 5 As part of the subsurface exploration, a boring was advanced adjacent to the toe of the steep slope area to the north of the site for purposes of assessing soil and groundwater conditions. The boring was advanced to a depth of 26.5 feet below existing grade, Please refer to the boring logs provided in Appendix A for a more detailed description of the subsurface conditions. Soil • • observed at the boring location• e• of loose to very • i (Unified Soil Classificationand poorly grad^}. advance outwash deposits. Overall density`. depth. Earth solutions NW, LLC Echelbarger Investments, LLC June 23, 2014 -I•ANEW$ According to the referenced geologic map, the subject site is underlain by advance outwash (Qva) deposits. Soil conditions observed at the boring location were generally consistent with advance outwash deposits. The National Resources Conservation Service (NRCS) Web Soil Survey indicates the site soils consist of Alderwood-Everett gravelly sandy loam. The soil conditions observed at the boring location were generally consistent with the NRCS soil mapping. Groundwater seepage was observed during our fieldwork on May 30, 2014 at a depth of approximately five and one-half feet below existing grades, which likely represents perched groundwater. Seepage should be expected in site excavations. Groundwater seepage rates and elevations fluctuate depending on many factors, including precipitation duration and intensity, the time of year, and soil conditions. In general, groundwater elevations and flow rates are higher during the winter, spring and early summer months. As part of this geotechnical engineering study, the referenced chapter of the Edmonds City Code was reviewed. Per the Edmonds City Code requirements, the following topics related to development plans and site conditions are addressed. Baft. ;.; During our fieldwork, we performed a visual slope reconnaissance across the steep slope area to the north of the site. The main focus of our reconnaissance was to identify signs of instability or erosion hazards along the site slopes. The typical instability indicators include features such as head scarps, tension cracks, hummocky terrain, groundwater seeps along the surface and erosion features such as gullet's and rills. During the slope reconnaissance, no signs of recent, large scale erosion or slope instability were observed. The slope is vegetated with mature trees, saplings, and ivy groundcover. In general, based on the slope reconnaissance, stability of the steep slope to the north of the property can be characterized as good. respectWith • landslide hazard areas, section :1 1 _i of the Edmonds City Code defines landslide hazard areas as "areaspotentially subject to landslides based on a combination geologic, topographic, and hydrologic factors, They include areas susceptible because of any combination of e !soil,•per (gradient), •p !'hydrology,or other factors. Within the city of Edmonds, landslide hazard areas specifically include: Earth Solutions NW, LLC Echelbarger Investments, LLC June 23, 2014 Areas of ancient or historic failures in earth subsidence 'and landslide hazard Lowe Associates and amended by the Edmonds which include all areas within the area as identified in the 1979 report of Robert 1985 report of GeoEngineers, Inc.; 2. Any area with a slope of 40 percent or steeper and with a vertical relief of 10 feet or more except areas composed of consolidated rock; 3. Any area potentially unstable as a result of rapid stream incision or stream bank erosion; and 4. Any area located on an alluvial fan, presently subject to, or potentially subject to, inundation by debris flow or deposition of stream -transported sediments." Based on site observation and the referenced critical area descending steep slope with gradient in excess of 50 per( subject property. Per the above definition of landslide ha; north of the subject property classifies as a landslide hazard 40 percent or steeper with a vertical relief of 10 feet or mor, not alter the landslide hazard area. reconnaissance report, a south- ent is located to the north of the and areas, the steep slope to the area based on a slope gradient of The proposed development will With respect to erosion hazard areas, section 23.80.020 of the Edmonds City Code defines erosion hazards as "at least those areas identified by the U.S. Department of Agriculture's Natural Resources Conservation Service as having a "moderate to severe", "severe", or "very severe" rill and inter -rill erosion hazard. Erosion hazard areas are also those areas impacted by shoreland and/or stream bank erosion. Within the city of Edmonds, erosion hazard areas include: Those areas of the city of Edmonds containing soils that may experience severe to very severe erosion hazard. This group of soils includes, but is not limited to, the following when they occur on slopes of 15 percent or greater: a. Alderwood soils (15 to 25 percent slopes); b. Alderwood/Everett series (25 to 70 percent slopes); c. Everett series (15 to 25 percent slopes); existing2. Any area with slopes of 15 percent or greater and impermeable soils interbedded with granular soils and springs or ground water seepage; and 3, Areas with significant visible evidence of ground water seepage, and which als* include landslide deposits regardlessof ••` Earth solutions NK LLC Echelbarger Investments, LLC S-3380 June 23, 2014 Page 5 As previously indicated, the on-site soils are generally consistent with Alderwood-Everett gravelly sandy loam, Based on the Edmonds City Code definition, the steep slope area to the north of site classifies as an erosion hazard area. The proposed development will not alter the erosion hazard area. The proposed development will involve demolition of the existing single-family residential structure and associated outbuildings and construction of two new single-family residential structures. Based on the referenced site plans, the grading will involve cuts and fills to establish level building pad areas, Based on the information provided to us, the proposed development will not impact the landslide hazard and erosion hazard area and adjacent properties. Based on the results of our study, in our opinion, the proposed development will not increase the threat of the geological hazard to adjacent properties beyond predevelopment conditions and will not adversely impact other critical areas. Minimum Buffer and BuildinqSetback Based on the results of our study and our understanding of the proposed development, in our opinion, the proposed development should incorporate a minimum no -disturbance buffer of 10 feet and a minimum building setback of 15 feet from the landslide hazard area. Based on the results of our study, in our opinion, construction of the proposed residential structures at the subject site is feasible from a geotechnical standpoint. The primary geotechnical considerations associated with the proposed development include foundation support, temporary excavations, retaining walls, and the suitability of the on-site soils for use as structural fill. The proposed be supported on • - •spread and continuous foundations bearing •' • •-• competent native soil,• ' •. -• native soil,or unsuitableCompetent soils suitable for support of foundations should be encountered at depths of approximately four to six feet below existing grades across the majority of the site. Slab-on grade floors should be supported on dense native soil, re -compacted native soil, or structural fill. Organic material exposed at subgrade elevations must be removed below design elevation and grades restored with structural fill, Where loose, organic or other encountered at or below the footing subgrade elevation,• • be removed and replaced with structural fill, as necessary. This study has been prepared for the exclusive use of Echelbarger Investments, LLC and his representatives. No warranty, expressed or implied, is made. This study has been prepared in a manner consistent with the level of care and skill ordinarily exercised by other members of the profession currently practicing under similar conditions in this area. Earth Solutions NW, LLC Echelbarger Investments, LLC June 23, 2014 NERNOTO Based on the referenced site plans and given the existing topography, we anticipate grading for the project will involve cuts of up to 10 to 12 feet to establish building pad and foundation subgrade alignments. Silt fencing and temporary erosion control measures should be placed along the perimeter of the site prior to beginning grading activities. Temporary construction entrances, consisting of at least six inches of quarry spalls can be considered in order to minimize off-site soil tracking and to provide a temporary road surface. Silt fences should be placed along the margins of the property. Interceptor swales and a temporary sediment pond may be necessary for control of surface water during construction. Erosion control measures should conform to the Washington State Department of Ecology (DOE) and City of Edmonds standards. From a geotechnical standpoint, the soils encountered at the boring location are generally suitable for use as structural fill. However, successful use of the on-site soils will largely be dictated by the moisture content of the soils at the time of placement and compaction. The site soils were generally in a moist to wet condition at the time of the exploration on May 30, 2014. Based on the conditions encountered during our fieldwork, the site soils will generally have a moderate sensitivity to moisture. During periods of dry weather, the on-site soils should generally be suitable for use as structural fill, provided the moisture content is at or near the optimum level at the time of placement. Successful placement and compaction of the on-site soils during periods of precipitation will be difficult. If the on-site soils cannot be successfully compacted, the use of an imported soil may be necessary. Imported soil intended for use as structural fill should consist of a well -graded granular soil with a moisture content that is at or near the optimum level. During wet weather conditions, imported soil intended for use as structural fill should consist of a well -graded granular soil with a fines content of 5 percent or less defined as the percent.passing the Number 200 sieve, based on the minus three-quarter inch fraction. Structural Fill Structural fill is defined as compacted soil placed in foundation, slab -on -grade, and roadway areas. Fills placed ♦ construct permanent slopes_ ♦ throughout retaining wall and utility trench backfill areas are also considered structural fill, Soils placed in structural areas should be placed in loose lifts of 12 inches or less and compacted to a relative compaction of 90 percent, based on the labor J atory maximum dry density as determined by the Modified Proctor Method (ASTM D-1557). For soil placed in utility trenches underlying structural areas, compaction requirements ar e dictated by the local city, county, or utility district, and in general are specified as 95 percent ' relative compaction. The upper 24 inches of foundation subgrade areas and the upper 12 inches of slab -on -grade and pavement subgrade areas should be compacted to a relative compaction of at least 95 percent. Earth Solutions NW, LLC Echelbarger Investments, LLC June 23, 2014 Am RR - M-91 The Federal Occupation Safety and Health Administration (OSHA) and the Washington Industrial Safety and Health�Act (WISHA) provide soil classification in terms of temporary slope inclinations. Based on the soil conditions encountered at the boring location, the loose to medium dense native soils encountered in the upper approximately four to six feet of the boring location and where fill and/or groundwater seepage is exposed are classified as Type C by OSHA/WISHA. Temporary slopes over four feet in height in Type C soils must be sloped no steeper than 1.5H:1V (Horizontal:Vertical). Medium dense to dense native soils encountered below approximately four to six feet where no groundwater seepage is exposed would be classified as Type B by OSHA/WISHA. Temporary slopes over four feet in height in Type B soils must be sloped no steeper than 1 H:1V. The presence of perched groundwater may cause caving of the temporary slopes due to hydrostatic pressure. ESNW should observe site excavations to confirm the soil type and allowable slope inclination are appropriate for the soil exposed by the excavation. If the recommended temporary slope inclination cannot be achieved, temporary shoring may be necessary to support excavations. Permanent slopes should maintain a gradient of 2H:1V, or flatter, and should be planted with vegetation to enhance stability and to minimize erosion. A representative of ESNW should observe temporary and permanent slopes to confirm the slope inclinations are suitable for the exposed soil conditions, and to provide additional excavation and slope recommendations, as necessary. Based on the results of our study, the proposed residential structures can be supported on conventional spread and continuous footings bearing on competent native soil, recompacted native soil, or structural fill. Based on the soil conditions encountered at the boring location, competent native soils suitable for support of foundations should be encountered at depths of about four to six feet below existing grades. Where loose or unsuitable soil conditions are observed at foundation subgrade elevations, compaction of the soils to the specifications of structural fill, or overexcavation and replacement with granular structural fill will be necessary. Organic material exposed at foundation subgrade elevations must be removed and grades restored with structural fill. Provided the structures will be supported as described above, the following parameters can •used for design of the new foundations: - e Allowable • bearing capacity 2,500 psf s Passive earth pressure 300 pef (equivalent fluid) o Coefficient of friction 0.40 A one-third increase in the allowable soil bearing capacity can be assumed for short-term wind a. • seismic loading • •• Earth Solutions NK LLC Echelbarger Investments, LLC ES -3380 June 23, 2014 Page 8 With structural loading as expected, total settlement in the range of one inch is anticipated, with differential settlement of about one-half inch. The majority of the settlements should occur during construction, as dead loads are applied. The 2012 IBC recognizes ASCE for seismic site class definitions. If the project will be permitted under the 2012 IBC, in accordance with Table 20.3-1 of ASCE, Minimum Design Loads for Buildings and Other Structures, Site Class D, should be used for design. In our opinion, the site is not susceptible to liquefaction. The soil relative density and the absence of an established shallow groundwater table is the primary basis for this opinion. Slab -on -grade floors should be supported on a firm and unyielding subgrade consisting of competent native soil or at least 12 inches of structural fill. Unstable or yielding areas of the subgrade should be recompacted or overexcavated and replaced with suitable structural fill prior to construction of the slab. A capillary break consisting of a minimum of four inches of free -draining crushed rock; or gravel should be placed below the slab. The free -draining material should have a fines content of 5 percent or less defined as the percent passing the Number 200 sieve, based on the minus three-quarters inch fraction. In areas where slab moisture is undesirable, installation of a vapor barrier below the slab should be considered. If used, the vapor barrier should consist of a material specifically designed to function as a vapor barrier and should be installed in accordance with the manufacturer's specifications. If retaining walls will be utilized, they should be designed to resist earth pressures and i?.pplicable surcharge loads. , , The following parameters can be used for retaining wall design: ® Active earth pressure (yielding condition) 35 pcf ® At -rest earth pressure (restrained condition) 50 pcf * Traffic surcharge (passenger vehicles) 70 psf (rectangular distribution) ® Passive earth pressure ® Coefficient of friction ® Seismic surcharge *Where H equals retained height Earth Solutions NW, LLC Me 6H* (active) 12H* (at -rest condition) Echelbarger Investments, LLC ES -3380 June 23, 2014 Page 9 Where sloping or other surcharge conditions will be present, supplement recommendations and design earth pressure values should be provided by ESNW. Drainage should be provided behind retaining walls such that hydrostatic pressures do not develop. If drainage is not provided, hydrostatic pressures should be included in the wall design. Retaining walls should be backfilled with free -draining material that extends along the height of the wall, and a distance of at least 18 inches behind the wall. The upper one foot of the wall backfill can consist of a less permeable soil, if desired. A perforated drain pipe should be placed along the base of the wall, and should be connected to an approved discharge location. A typical retaining wall drainage detail is provided as Plate 3. Groundwater seepage was observed during our fieldwork on May 30, 2014 at a depth of approximately five and one-half feet below existing grades, which likely represents perched groundwater. Seepage should be expected in site excavations, particularly in the winter, spring and early summer months. Temporary measures to control groundwater seepage and surface water runoff during construction will likely involve passive elements such as interceptor trenches and sumps, as necessary. Surface water should not be allowed to runoff over sloped areas and should not be allowed to pond near the top of sloped areas or retaining structures. Surface grades must be designed • direct - from buildings. grade adjacent • buildings should be sloped away from the buildings at a gradient of at least 2 percent for a horizontal distance • ' our opinion,perimeter f•• • drains should be installed at or below the invert of building •o • r typical footing drain detail is provided • Plate o report.this In our opinion, the soils observed at the boring location are generally suitable for support of utilities. In general, the soils observed at the boring location should be suitable for use as structural backfill in the utility trench excavations, provided the soil is at or near the optimum moisture content at the time of placement and compaction. Moisture conditioning of the soils may be necessary at some locations prior to use as structural fill. Utility trench backfill should be placed and compacted to the specifications of structural fill provided in this report, or to the applicable requirements of the City of Edmonds. The performance of site pavements is largely related to the condition of the underlying subgrade. To ensure adequate pavement performance, the subgrade should be in a firm and unyielding condition whensubjected to proofrolling with a loaded dump truck. Structural fill in pavement areas should be compacted to the specifications detailed in the Site Preparation and Eatthwork section of this report. It is possible that soft, wet, or otherwise unsuitable subgrade areas may still exist after base grading activities. Areas of unsuitable or yielding subgrade conditions may require remedial measures such as overexcavation and replacement with structural fill or thicker . • rock sectionsprior to pavement. - treatment of •• .•- soil can also be consideredor stabilizing pavement r• •^ areas. Earth Solutions NW, LLC Echelbarger Investments, LLC June 23, 2014 For relatively lightly loaded pavements subjected to automobiles and occasional truck traffic, the following sections can be considered for preliminary design: ® Two inches of hot mix asphalt (HMA) placed over four inches of crushed rock base (CRB), or; ® Two inches of HMA placed over three inches of asphalt treated base (ATB). The HMA, CRIB and ATB materials should conform to WSDOT specifications. The recommendations and! conclusions provided in this geotechnical engineering study are professional opinions consistent with the level of care and skill that is typical of other members in the profession currently practicing under similar conditions in this area. A warranty is not expressed or implied. Variations in the soil and groundwater conditions observed at the boring location may exist, and may not become evident until construction. ESNW should reevaluate the conclusions in this geotechnical engineering study if variations are encountered. ESNW should have an opportunity to review the final design with respect to the geotechnical recommendations provided in this report. ESNW should also be retained to provide testing and consultation services during'construction. Earth Solutions NK LLC Reference: Snohomish Map 454 By The The Rand MCN 32nd Editio =0100�6.6, . ..... . .. . -- -I---- NOTE: This plate may contain areas of color. ESNW cannot be Drwn. GLS Date 06/19/2014 Proj. No. 3380 responsible for any subsequent misinterpretation of the information Checked HTW Date June 2014 Plate 1 resulting from black & white reproductions of this plate. I I 7d i i i i i I i I I 220 210 ALLEY nne nnc Ono 040 041f oda 04A MAIN B_1—L Approximate Location of ESNW Boring, Proj. No. ES -3380, May 2014 ®' Subject Site L–j Existing Building NOTE: The graphics shown on this plate are not intended for design purposes or precise scale measurements, but only to illustrate the approximate test locations relative to the approximate locations of existing and / or proposed site features. The information illustrated is largely based on data provided by the client at the time of our study. ESNW cannot be responsible for subsequent design changes or interpretation of the data by others. NOTE: This plate may contain areas of color. ESNW cannot be responsible for any subsequent misinterpretation of the information resulting from black & white reproductions of this plate. STREET 210 0 15 30 .0 —ME= Scale in Feet Drwn. GLS Date 06/19/2014 Proj. No. 3380 Checked HTW Date June 2014 Plate 2 am o 0: 0 0 0 0 0 0 0 0 0 vo 0 m 00 0 e 0 o-bo 0 oop o 00 0 0000 0 0 O. O o 0 0 00 0000 00 00 0 -6 00000 ` 0 0 O 5 0 00 0 0 o 0 0 0 0 �0 0 o O o o 00 0 0 00 0 0 0 o Q O o 0 c o 0 0 0 000 0�0 o Q000.00o �o 0000 0 0 0 0 o 0 0o 0 o e o 00 0 0 oo 0 0 o 0 oo o o o 0o.000a .. oo . o 8 0 o�oo�o0 o oo �o 0o oo a o 0 oo oo 0 p0000 00 000 00 0 e 0 0 0000 0 00 0 o 0 0 o 0 ...... ® Free Draining Backfill should consist of soil having less than 5 percent fines. Percent passing #4 should be 25 to 75 percent. e Sheet Drain may be feasible in lieu of Free Draining Backfill, per ESNW recommendations. ® Drain Pipe should consist of perforated, rigid PVC Pipe surrounded with V Drain Rock. 1000 0--0-00'- o Free Draining Structural Backfill var0vo 1 inch Drain Rock Structural Fill Perforated Drain Pipe (Surround In Drain Rock) SCHEMATIC ONLY - NOT TO SCALE NOT A CONSTRUCTION DRAWING RETAINING WALL DRAINAGE DETAIL 1035 Main Street Edmonds, Washington Drwn. GLS Date 06/23/2014 Proj, No. 3380 Checked HTW Date June 2014 Plate 3 Perforated Rigid Drain Pipe (Surround with 1" Rock) li[6Yl ® Do NOT tie roof downspouts to Footing Drain. ® Surface Seal to consist of 12" of less permeable, suitable soil. Slope away from building. xW49r:=12,111 1 Surface Seal; native soil or other low permeability material. 1" Drain Rock aoa SCHEMATIC ONLY - NOT TO SCALE NOT A CONSTRUCTION DRAWING Drwn. GLS I Date 06/23/2014 Proj. No. 3380 Checked HTW Date June 2014 Plate 4 ;, 'T " ?. '' a 4, The subsurface conditions at the site were explored by advancing one boring at the approximate locations illustrated on Plate 2 of this report. The boring logs are provided in this Appendix. The subsurface exploration was completed on May 30, 2014. The boring was advanced to a maximum depth of 26.5 feet below existing grades. Logs of the boring advanced by ESNW are presented in Appendix A. The final logs represent the interpretations of the field logs and the results of laboratory analyses. The stratification lines on the logs represent the approximate boundaries between soil types. In actuality, the transitions may be more gradual. Earth Solutions NW, LLC DUAL SYMBOLS are used to indicate borderline soil classifications. The discussion in the text of this report is necessary for a proper understanding of the natw-* of the material presented in the attached logs. SYMBO TYPICAL MAJ OR DIVISIONS DESCRIPTIONS GRAPH LETTER CLEAN WELL -GRADED GRAVELS, GRAVEL - GRAVEL GRAVELS GW SAND MIXTURES, LITTLE OR NO SAND FINES AND GRAVELLY POORLY -GRADED GRAVELS, SOILS (LITTLE OR NO FINES) 0 GP GRAVEL - SAND MIXTURES, LITTLE OR NO FINES COARSE 0 GRAINED GRAVELS WITH GM SILTY GRAVELS, GRAVEL-SAND- RAVEL-SAND-SOILS SOILS MORE THAN 50% FINES a SILT MIXTURES OF COARSE . FRACTION RETAINED ON NO. 4 SIEVE (APPRECIABLE GC CLAYEY GRAVELS, GRAVEL- SAND- AND-AMOUNT AMOUNTOF FINES) CLAY MIXTURES CLEAN SANDS i�Yai I.X SW WELL -GRADED SANDS, GRAVELLY MORE THAN 50% SAND SANDS, LITTLE OR NO FINES OF MATERIAL IS AND S P POORLY -GRADED SANDS, GRAVELLY SAND, LITTLE OR NO LARGER THAN NO. 200 SIEVE SANDY SOILS SIZE (LITTLE OR NO FIN ES) FINES SANDS WITH s m SILTY SANDS, SAND - SILT MORE THAN 50% FINES MIXTURES OF COARSE FRACTION PASSING ON NO. 4 SIEVE (APPRECIABLE sc CLAYEY SANDS, SAND - CLAY AMOUNT OF FINES) MIXTURES INORGANIC SILTS AND VERY FINE ML SANDS, ROCK FLOUR, SILTY OR CLAYEY FINE SANDS OR CLAYEY SILTS WITH SLIGHT PLASTICITY SILTS INORGANIC CLAYS OF LOW TO FINE LIQUID LIMIT AND AND CL MEDIUM PLASTICITY, GRAVELLY GRAINED LESS THAN 50 CLAYS, SANDY CLAYS, SILTY CLAYS, LEAN CLAYS SOILS OL ORGANIC SILTS AND ORGANIC SILTY CLAYS OF LOW PLASTICITY MORE THAN 50% INORGANIC SILTS, MICACEOUS OR OF MATERIAL IS MH DIATOMACEOUS FINE SAND OR SMALLER THAN SILTY SOILS NO. 200 SIEVE CH I CLAYS OF HIGH SIZE SILTS LIQUID LIMITINORGANIC AND GREATER THAN 50 PLASTICITY CLAYS OH ORGANIC CLAYS OF MEDIUM TO HIGH PLASTICITY, ORGANIC SILTS PEAT, HUMUS, SWAMP SOILS WITH HIGHLY ORGANIC SOILSPT HIGH ORGANIC CONTENTS DUAL SYMBOLS are used to indicate borderline soil classifications. The discussion in the text of this report is necessary for a proper understanding of the natw-* of the material presented in the attached logs. Earth Solutions NW BORING NUMBER B-1 1805 - 136th Place N.E., Suite 201 PAGE 1 OF 2 Bellevue, Washington 98005 Telephone: 4254494704 Fax: 425-449-4711 CLIENT _Echelbarger Investments, LLC _ PROJECT NAME 1035 MainStreet_ PROJECT NUMBER 3380 _ PROJECT LOCATION DATE STARTED 5130/14 _. COMPLETED _5!30/14 _ GROUND ELEVATION 205 ftHOLE SIZE ........ DRILLING CONTRACTOR Boretec GROUND WATER LEVELS: DRILLING METHOD HSA AT TIME OF DRILLING LOGGED BY HTWCHECKED BY HTW AT END OF DRILLING NOTES Brambles_ _ AFTER DRILLING — = hW i --:D a-- $ _j CO > O Z) Q TESTS v ° O MATERIAL DESCRIPTION _j � ov �z 0z 0 SS 1 1001 5-4-4 (8) SS 11001 6-8-10 (18) SP_ MC = 25.40% SM Fines = 8.60% MC = 23.10% Fines = 4.00% SS 1 1001 11 33)18 1 MC = 27.20% SS 1 100 1 20-50/5" I MC = 19.90% M Brown silty SAND, loose to medium dense, ____..._-_. _---.---_._____ Black poorly graded SAND with silt, loose, wet [USDA Classification: gravelly SAND] -moderate seepage --_---_Brown _.._._....__-silty.._-....SAND._._..---,._...-__medium._...__...--den---ss-ae,-�_..wet-_.. ,— [USDA Classification: SAND] poorly graded SAND, very dense, moist to wet (Continued Next Page) SP 1 Gray silty SAND, very dense, wet I SS I 100 I 50/3" ( FiMnes = 23.0% I III [USDA Classification: loamy SAND] Boring terminated at 26.5 feet below existing grade. Groundwater seepage encountered at 5.5 feet during drilling. Boring backfilled with bentonite: Bottom of hole at 26.5 feet. Earth Solutions NW BORING NUMBER B-1 1805 - 136th Place N.E., Suite 201 Bellevue, Washington 98005 PAGE 2 OF 2 Telephone: 425449-4704 Fax: 425-449-4711 CLIENT Echelbar eg r InvestmentsL LLC PROJECT NAME 9035 Main Street_v PROJECT NUMBER 3380 PROJECT LOCATION Edtnorid$_4JVashington = f- WW n TESTS U p MATERIAL DESCRIPTION W j o m O> az w Uz C9 2Q Orly poorly graded SAND, very dense, moist to wet.(conAnoe�Y) -SS 100 1950 i MC = 21.40% — ---- J / SP 1 Gray silty SAND, very dense, wet I SS I 100 I 50/3" ( FiMnes = 23.0% I III [USDA Classification: loamy SAND] Boring terminated at 26.5 feet below existing grade. Groundwater seepage encountered at 5.5 feet during drilling. Boring backfilled with bentonite: Bottom of hole at 26.5 feet. W' "yam Earth Solutions NW, LLC Earth Solutions NW GRAIN SIZE DISTRIBUTION, 1805 -136th Place N * E., Suite 201 Bellevue, WA 98005 Telephone: 425-2843300 CLIENT Echelbarqher Investment LLC PROJECT NAME, 1035 Edmonds PROJECT NUMBER ES -3380 PROJECT LOCATION Edmonds GRAIN SIZE IN MILLIMETERS COBBLESGRAVEL SAND SILT OR CLAY :�ars fine coarse I medium E3cimen Identification Classification B-1.___ 5.Oft. —USDA: Black Gravelly Sand. USCS: SP-SM1with G * ravel. B-1 7.6ft. USDA: Brown Sand. USCS: SM. B-1 USDA: Gray Loamy Sand., USCS: SK =MW 01 Cc CU 1.00 6.49 Specimen Identification D100 D60 D30 DIO %Silt I %C(ay 0 B-1 5.0ft. 19 0.69 0.232 0.091 8.6 0 B 7 5ft. 9.5 0.241 0.157 14.0 LU Z-\ B-1 25.Oft. 4.75 0.228 0.148 23.7 7 .EMAIL ONLY Echelbarger 400 981h Street Southwest Lynnwood, go: 1' , Earth Solutions NW, LLC Echelbarger Investments, LLC 4001 — 198' Street Southwest, Suite Lynnwood, Washington 98036 1 rONOM17MIMM Subject: Response to Comments City of Edmonds — Plan Review Comments #2 1036 and 1037 Main Street Edmonds, Washington Reference: City of Edmonds Plan Review Comments #2 Project # 2014-0380 and 2014-0381 July 21, 2014 Insight Engineering Co. Site Plans March 31, 2014 Earth Solutions NK LLC Geotechnical Engineering Study ES -3380, June 23, 2014 Dear Mr. Echelbarger: Earth Solutions NW LLC * Geotechnical Engineering * construction Monitoring * Environmental Sciences As requested, Earth Solutions NW, LLC (ESN\N) has prepared this letter addressing the referenced City of Edmonds Development Services Department review comments memo. The referenced documents have been reviewed in preparation of this letter. The comments pertinent to the geotechnical aspects of the project are provided below, followed by our responses. City of Edmonds Comment 1 -- Geotechnical report: Thank you for submitting the Earth Solutions report dated Juno; 23, 2014. It was noted in the report that the geotech had riot had the opportunity to review the associated grading plans; please have Earth Solutions review the grading and TEC plan (Sheet C2) and the associated drainage and utility plan (Sheet Cl). 18013 - 1361h Place N41- Suile 201 o Bellevue, WA 980115 11 025) 449-47011 " FAX (4)5) 149-4711 E-Ohelbarger Investments, LLC ES -3380,01 July 30, 2014 Page 2 Because the proposed 4' retaining wall will be constructed in a critical area or buffer, it must be designed by a licensed engineer. Submit section and elevation views for the wall along with design calculations and a letter from the engineer as identified in Building Division Handout #1362. We trust this response to City of Edmonds review comments meets your current needs. Should you have questions, or if additional information is required., please call. Sincerely, .... . ... Henry T Wright, E.13, Staff Engineer Attachment: CornerStone Gravity Well Design mma U 'iA I ((� 30( 7 Raymond A. Coglas, P.E. Principal Earth Solutions NK LLC OW Diainap HI 3M loan GOata� Stone ,Wnm}7 q.fw" Cnmhm Pak fWddflVkr 7. (No Fh%ay A 8k w';�^ A Ur Max Wall B"' f7t crib �1 �� N, Competent @t1k * v (of rf;a®tr� / d��d�rrf dfd '°' 'M PO 4" Lma°ory kv,'i COUPS "'rYPICAL GRAVITY WALI., DETAIL., W WA .,. TO ,. CA1 '(rnWor'cecl backfill sto"aatt be W;OMPaCted to a, rrarO7rtaUflt of 95% (A 1h' rtaaMrrtIrU'rl MY d e R":arfy as (jetennine(I by ASTM D1 ,57X the moisture content (V the backffll rnatef'01 ['.'Oor lea and during compaction staa H be plus of uvr, ur ; % ref me OPUMUM 1110Strad. content, The waatl footings shall be Otasefved by the eolechrr cast Engineer on a WH - tmie Dass, Testing of the compacted ba.°rc; ldH sttaatf be performed ed by the owner. at least Or'jt`:i� eaic-f,y two tffts of b,ackfrll p0c(.,"merit aar ,t compara.ataan As a m& Pulham, qr.lalbt 113Sm"ance shouN Gr clud" e fr°jr,nd:tatrnn Soil 4)sp 'dW tq�a"n' SW and backfill testing, vefif c tkwi of r es,gnparaaraaa te'°ra mRd dOaoer' aatimi of d;onst,G'Ud,Jr;;rC"B f0f �rar,rrat r,aoirpls«:rnc w1h clest' n dNraa' mm'p aard st.N drcartY0."iils, „ danlmu� r �� ,,, as d a�°r"• t, i ,tr �r,7 ,,� %��,r�ta �C 6 77 Com rst ne Gravity Wail 1035 Main Street Edmonds, Washington 30 M �, G1t t + to rp HTVV tante 12912014 Prof No. �i380 1 �� Yr rONAI � m, heckwf HTVV Pmts t