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Helix Design Group,Inc.—Greenwood Heating&Air Conditioning,Everett,WA April 22,2022
<br /> Geotechnical Engineering Report Z0219
<br /> Everett,and the larger Puget Sound area in general has been glaciated a number of times over the
<br /> last 2.4 million years. The most recent of these glaciations, the Vashon Stade of the Fraser
<br /> glaciation, receded from this region approximately 13,500 years ago. Glacial till deposits
<br /> encountered on site originated from this Vashon era. Glacial till soils are typically described as
<br /> consisting of a compact,coherent mixture of silt,clay,sand and gravel-sized clasts. These deposits
<br /> are typically encountered in a compact relative consistency given the fact that they were over-
<br /> ridden by the ice mass after deposition.
<br /> The National Cooperative Soil Survey (NCSS) for the Snohomish County Area, Washington,
<br /> classifies soils on site as 5—Alderwood-Urban land complex,2 to 8 percent slopes. This soil series
<br /> reportedly formed within basal glacial till deposits and comprises gravelly sandy loam. In the
<br /> Geologic Map of Surficial Deposits in the Seattle 30'x 60'Quadrangle, Washington, as prepared by the
<br /> United States Department of the Interior United States Geological Survey(USGS)(1993),the project
<br /> area is mapped as containing Qvt;or Vashon-aged glacial till. An excerpt from this publication is
<br /> presented below. ��Sao 1 • Y Nto 1 ..--\. ,' : . e , 't\\1 ., :
<br /> . '.1:,,,.:01,,,,,• , 1\
<br /> A, btire `T, •AIM Ft t., 1 1 ;9d �, NTY •I*(3tr} 'i �i -i 1,Qn
<br /> QW 4mak .,Fai ulu : t
<br /> 1 ' I t
<br /> f .� _ aa.,.�.
<br /> WIC . ,-- -, 7._:. ,-•
<br /> va ',+ ``; _ \T-- Project Site -- : ' 1
<br /> 16_4) ,-Qvt . ,\ ,,, it
<br /> F C .1 ' -l ', .1 . •
<br /> '
<br /> r QYa i i xuc+r i( .
<br /> Qva
<br /> i r , iit w-39
<br /> ^� Qvi i
<br /> Oc;� ,a . �_ J �i —
<br /> ......\
<br /> tt r Qtb /-._J7 3 Qvt .. __tom
<br /> •
<br /> Excerpt from the Geologic Map of Surficial Deposits in the Seattle 30'60' Quadrangle,
<br /> Washington (USGS)(1993)
<br /> Our subsurface explorations generally corresponded with the site classifications prepared by both
<br /> the NCSS and DNR.
<br /> The enclosed exploration logs (Appendix A) provide a detailed description of the soil strata
<br /> encountered in our subsurface exploration.
<br /> Migizi Group,Inc. Page 4 of 16
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