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A • <br /> C C1 BA LT Cobalt Geosciences,LLC <br /> GEOSC'IENCES P.O.Box82243 <br /> Kenmore,Washington 98028 <br /> April 6,2021 <br /> RR Foundation Specialist <br /> Attn:Mr.Cory Myron <br /> coryPrrspecialist.net <br /> RE: Limited Geotechnical Evaluation <br /> Foundation Mitigation <br /> 518 51st Street SW <br /> Everett,Washington <br /> In accordance with your authorization, Cobalt Geosciences, LLC has prepared this letter to <br /> discuss the results of our limited geotechnical evaluation at the above-referenced location. <br /> Site and Project Description <br /> The site is located at 518 515t Street SW in Everett, Washington. The site consists of one <br /> rectangular shaped parcel(No.2904360040460o)with a total area of about o.26 acres. <br /> The northern portion of the property is developed with a single-family residence, driveway, <br /> detached structures, and landscaped areas. The remainder of the property is vegetated with <br /> grasses,bushes,and sparse trees. <br /> The southern third of the property slopes downward from north to south into a west-sloping <br /> ravine area. Within the property,the relief is about 35 feet with magnitudes of 3o to 5o percent. <br /> The overall slope has similar slope magnitudes but total relief of about 8o feet. <br /> The site is bordered to the east and west by residential properties, to the south by the <br /> undeveloped ravine feature,and to the north by 51st Street SW. <br /> We understand that the eastern and southern portions of the residence have settled up to 6 inches <br /> over time. The project includes installation of at least 17 helical anchors,possible steel channel, <br /> and steel connections. Anchors are anticipated to be driven to refusal below foundation elements. <br /> Lifting of the residence will not be performed. <br /> Area Geology <br /> The site lies within the Puget Lowland. The lowland is part of a regional north-south trending <br /> trough that extends from southwestern British Columbia to near Eugene, Oregon. North of <br /> Olympia, Washington,this lowland is glacially carved, with a depositional and erosional history <br /> including at least four separate glacial advances/retreats. The Puget Lowland is bounded to the <br /> west by the Olympic Mountains and to the east by the Cascade Range. The lowland is filled with <br /> glacial and non-glacial sediments consisting of interbedded gravel,sand,silt,till,and peat lenses. <br /> The Geologic Map of Washington — Northwest Quadrant,indicates that the site is underlain by <br /> Vashon Glacial Till and at depth by Vashon Advance Outwash. <br /> www.cobaltgeo.com (206)331-1097 <br />