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and gravel, and glacially formed lake clay and silt. The repeated glacial action has resulted in numerous <br /> north-south trending ridges,with intervening valleys filled with post-glacial alluvium and/or marine deposits. <br /> The most recent glacial cycle of sediment deposits is referred to as the Vashon Drift, occurring between <br /> 13,500 and 15,000 years ago. <br /> Geologic maps of the project area identify subsurface soils to consist primarily of glacial till of the Vashon <br /> Drift. Accumulations of organic material and peat are often encountered near or within water-filled <br /> depressions overlying the glacial till (in swamps, bogs, and lake areas). Localized areas of organic silt and <br /> peat are also mapped in the wetland area located south of the operating base,and in the vicinity of Boeing <br /> Lake located southwest of the site across Airport Road. <br /> Glacial till typically consists of a heterogeneous mixture of sand, gravel, cobbles and occasional boulders <br /> in a silt and clay matrix that was deposited beneath a glacier. Because glacial till has been overridden by <br /> thousands of feet of ice, it is typically dense to very dense. Glacial till in the Everett area typically mantles <br /> hills, ridges, and slopes and varies in thickness from about 10 to 60 feet. <br /> Subsurface soils encountered in our explorations are consistent with the geologic mapping and our previous <br /> explorations completed at the site. We encountered shallow surficial fill associated with building and <br /> parking lot construction overlying glacial till in all ___ <br /> three of the borings. Specific details of subsurface 1 1( 1' _ <br /> :_� <br /> � , : <br /> conditions encountered in our explorations are 1 .1 1 1 Iti <br /> presented below. W ,,,s MOM ,� 4 <br /> r <br /> Iv <br /> udri site a.. <br /> 3.2. Surface Conditions <br /> Existing surface conditions at the site consist <br /> primarily of the asphalt paved parking lot surrounding <br /> the existing two-story concrete building. Small <br /> landscape islands are located within the parking lot. <br /> The ground surface is relatively flat and slopes gently <br /> down towards the northeast. The existing grades <br /> range from about Elevation 570 feet at the southwest <br /> Longitudinal cracking on east side of parking lot,looking west. <br /> corner of the site to Elevation 561 at the northeast <br /> corner of the site. . <br /> The pavement surfacing encountered in our current , .,., V .` <br /> borings consists of 3 to 6 inches of asphalt concrete : ' . . i - ,: <, _ k 5 <br /> overlying 2 to 3 inches of base course material. <br /> Previous borings completed in the south site area <br /> encountered 7 inches of asphalt concrete with no ;'« i1.,.r : "`"' `' <br /> E i k� <br /> underlying base course. We observed that the , i ,. d <br /> pavement exhibits slight distress consisting of :rr 1 ;y «'" t. • -* rF; ''-i' : <br /> occasional longitudinal cracks and minor ; �p <br /> depressions and cracks at utility patches and around 31#�2t„� ` " t.r <br /> light poles(refer to photos).Vegetation was observed _ �2- ,42;; <br /> to be growing within the cracks at various locations Depression along utility trench,looking east. <br /> across the parking lot. <br /> GEOENGINEERS /7 November 14,2019 Page 2 <br /> File No.2095-019-07 <br />