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Geotechnical Engineering Investigation Page 8 of 24 <br /> New Residential Subdivision <br /> 2706 Pock Lane <br /> Stockton, CA 95205 <br /> March 30, 2021 CTE Job # 25-1097G <br /> GREAT VALLEY 4B,GORDON 45.53 6.80 1.3 <br /> VALLEY <br /> ORTIGALITA 45.58 7.10 1.0 <br /> CALAVERAS;CC 45.60 6.39 15.0 <br /> CALAVERAS;CC+CS 45.60 6.50 15.0 <br /> HAYWARD-RODGERS CREEK; 46.57 7.00 9.0 <br /> HN+HS <br /> HAYWARD-RODGERS CREEK; 46.57 7.33 9.0 <br /> RC+HN+HS <br /> HAYWARD RODGERS CREEK;HS 46.57 6.78 9.0 <br /> 4.7 Liquefaction and Seismic Settlement Evaluation <br /> Liquefaction occurs when saturated fine-grained sands and/or silts lose their physical strength <br /> temporarily during earthquake induced shaking and behave as a liquid. This is due to loss of <br /> point-to-point grain contact and transfer of normal stress to the pore water. Liquefaction potential <br /> varies with water level, soil type, material gradation, relative density, and probable intensity and <br /> duration of ground shaking. <br /> The California Geological Survey (CGS) has designated certain areas within California as <br /> potential liquefaction hazard zones. These mapped areas are considered at risk of liquefaction- <br /> related ground failure during a seismic event based upon mapped surficial deposits. The project <br /> site is not currently mapped for potential liquefaction hazard by the CGS (refer to CGS website: <br /> (http://maps.conservation.ca.gov/cgs/infonnationwarehouse/index.html?map=re ug lator gps). <br /> Based on readily available published geologic information, there is no historical record of <br /> liquefaction occurring at the site. <br /> Based on our explorations the near surface soil deposits at the site consist of very stiff to hard <br /> sandy clays (CL), with a thin layer of hard low plastic sandy silts (ML), underlain by hard sandy <br /> clays(CL).Based on the site location and relatively low intensity of ground shaking,the relatively <br /> deep ground water and the consistency of the subsurface materials the possibility of large <br /> differential settlements due to seismic dry sand settlement or liquefaction is considered low. <br /> Therefore, the potential for catastrophic building collapse due to a seismic liquefaction event are <br />