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ggg <br /> IN W. �. <br /> Exxon Company USA <br /> �~ 202/225-2745.02 <br /> August 21 , 1987 <br /> GROUNDWATER SAN--vma <br /> Monitoring wells 4 and 5 were developed by hand hailing <br /> ry_ methods on June 22, 1987. Water samples were obtained from each <br /> of the five wells on June 26 , 1987. The samples were collected <br /> with an EPA approved teflon sampler, preserved and transported <br /> under Chain-of-Custody in accordance with GTI 's Sop's 9,. 10 and <br /> 11 (see A <br /> i PPendix II) . The samples were analyzed for TVH and HTEX <br /> by Modified EPA Method 602. <br /> SITE CONDITIONS <br /> ' NYDROGEOLOGY <br /> The geologic formations in the Stockton area can be <br /> clas§ified in two general groups ; semi consolidated. saline waver <br /> bearing units .and the overlying unconsolidated fresh water <br /> bearing ` units. The : semiconsoIidated rock Units are composed of <br /> the Mahrten and the Valley Spring Formations. These formations } <br /> 1 are of volcanic origin and -contain andeaitic. and rhyolitic. breccia„ tuff anti. ash The <br /> groundwater . within these two <br /> �k <br /> formations . is .,saline and Is separated from the overlying Presh <br /> 4r' <br /> water bearing units by an impermeable bed within-_ the-__upper . <br /> Mehrten fiormation. <br /> The unconsolidated <br /> units + consist of alluvial sediments of <br /> the , Victor Formation , Arroyo Seco Gravel and the Laguna' <br /> Formation. These formations are <br /> ..composed of gravels, sands, <br /> silts and clays which have a total thickness Of apoffi-niffa,=i <br /> proximately 1000 feet Good quality. groundwater is present in these units. <br /> r r <br />