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3.2. Geology <br /> Published geologic information for the project vicinity includes the United States Geological Survey(USGS) <br /> map titled The Geologic Map of the Snohomish Quadrangle, Snohomish County, Washington (USGS 1985). <br /> Mapped soils in the immediate project vicinity consist of glacially consolidated Vashon Till deposits <br /> (glacial till). <br /> Glacial till is generally a non-sorted, non-stratified mixture of sand, gravel and silt that has been overridden <br /> by several thousand feet of ice.Till typically has high shear strength, low consolidation and low permeability <br /> characteristics in the undisturbed state. It typically develops a weathered zone of less dense till where <br /> seasonal groundwater perches on top of the relatively impermeabl a_inweathered till and the perched <br /> groundwater occurs as seepage following the site topography. <br /> 3.3. Subsurface Soil Conditions <br /> GeoEngineers' understanding of subsurface condition', i., Lased on the ngs drilled for this project, and <br /> our review of the geologic map. Competent glari,ilk consolidated soils ;;,: .,listing of glacial till were <br /> encountered at relatively shallow depths in the foctt print of the proposed addition 1, which is consistent with <br /> the geologic map. Materials encountered at the site goon rally consisted of the follo�.�ing: <br /> is Asphalt Pavement:Asphalt concret :ti ivement was observed in each of the borings.Asphalt pavement <br /> was observed to range from 2 to 3 irl+ hen flick. No crushed surfacing base course (CSBC) materials <br /> were encountered below the pavement in the borings. <br /> • Fill: Fill was encountered below the asph ,lt pavement in all boring., ihe fill generally consists of loose <br /> to medium dense san I !rh, HI( end variable �, avel content.The thickr ss of fill decreased in thickness <br /> from north to south n !d was ok, ,°irved to be .,ppiu on lately 8, " ' and 2 feet thick in boring B-1, B-2, <br /> and B-3, respectively <br /> • Glacial Till: Glacial till depo Its ,vor encountered i,Llow the fill at depths ranging from 2 feet (boring <br /> B-3)to , log B-1) beov. xisting si(l' grades. ;facial till soils consisted of very dense silty sand <br /> to silt with variable gravel. <br /> 3.4. Groundwater Conditions <br /> No groundwater v,.as observed d a;i;ig drilling. However, due to the density and low permeability of the <br /> relatively unweathL r,-,-1 glacial till cl I_osits perched groundwater should be expected above the relatively <br /> unweathered till and ,0 ,rary as a i.+llction of season, precipitation and other factors. Perched seepage <br /> zones should be expected! ehov 111J relatively unweathered glacial till deposits and in permeable layers <br /> within the till deposits. <br /> 4.0 CONCLUSIONS AND RECOMMENDATIONS <br /> A summary of the geotechnical considerations is provided below.The summary is presented for introductory <br /> purposes only and should be used in conjunction with the complete recommendations presented in this <br /> report. <br /> ■ The site is best classified as Site Class C in accordance with the 2018 International Building Code(IBC). <br /> GEOENGINEERS� December6,2021 Page 2 <br /> File No.24459-003-00 <br />