Laserfiche WebLink
L Ned <br /> Geology in the vicinity of the site was mapped as the lower member of the Modesto Formation, <br /> which is comprised of Quaternary Alluvial deposits (Wagner et.al.,1981). Site soils have been <br /> characterized by Gallardo,Barber,and SES. The site is covered by an approximate 6-inch thick <br /> layer of asphalt chip seal and gently slopes to the south. In general,subsurface soils encountered at <br /> the site consist primarily of interbedded layers of sand,silty sand;and clayey sand! Site soil <br /> have been characterized to a maximum depth of 60 feet BGS beneath <br /> MW-7. the site and 70 feet BGS at well <br /> Appendix D,Figure D-1 shows the location of geologic cross sections,and Appendix D,Figures D-2 <br /> and D-3 present the geologic cross sections for the site. Boring logs are included in historic reports <br /> prepared by Gallardo,Barber,and SES. <br /> 4.4 Site Hydrogeology <br /> In general,the unconfined shallow groundwater that is present beneath the WOS site ranges from <br /> approximately 48 to 60 feet BGS. Some perched groundwater has been found between 15 to 20 feet <br /> BGS in the general site area,potentially due to seasonal accumulation(Barber,2008). <br /> The direction of groundwater flow beneath the site has historically been to the north/northeast and <br /> the gradient has varied from approximately 0.001 to 0.008 ft/ft. A groundwater contour map for <br /> the January 19,2010 monitoring event is presented as Figure 3. A hydrograph showing the historic <br /> Lgroundwater elevations for previous monitoring events is presented as Figure 5. Historic <br /> groundwater elevation data for the site are included in Appendix B,Table B-2. <br /> Figure 5 <br /> Water Level Hydrographs <br /> Western oil And Spreading,Inc.,Acampo Plant Site <br /> Acampo,California <br /> 7.5 <br />` a <br /> � ss A A <br /> 3.5 <br /> a _f MW-1 <br /> TVD <br /> Q -BMW-2 <br /> d <br /> 3 1.5 -4"--MW-3 <br /> �-MW5 <br /> C7 <br /> -0.5 _.*-MW3 <br /> MW-7 <br /> I -2.5 <br /> ��\oy <br /> titi\ b� tiL\ b� 1ry� b� 4K b� 1ry\ b\ try\ b\ti 1�\rye h�ry� �1\ryh \ryry� <br /> Date <br /> \\Eureka\projects\2007\007152-WOS\PUBS\rpt\2o100324-1stHal@o'IOGWMR&RFC.doc <br /> 7 <br />