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-P!ff SF�u A <br /> "sAFVArNU <br /> Working to Restore Nature <br /> 3 <br /> Proximity to Wells <br /> Based on information provided by Teichert, there are three industrial supply wells and one <br /> domestic well (Plate 2) onsite. Because the property boundaries are greater than 1/4-mile <br /> radius from the study area, a well search at the California Department of Water Resources <br /> was not conducted. <br /> Regional Geology and Hydrogeology_ <br /> The site is underlain by the Turlock Lake Formation, which consists of Pli o-Pleistocene <br /> nonmarine sedimentary deposits ranging from gravel to clay (Rogers, T.H. 1966). To the <br /> west are Middle to Lower Pliocene nonmarine sediments. Beneath the Pliocene deposits <br /> lie Upper Cretaceous marine sedimentary rocks. The site is in an area of northwest- <br /> southeast trending faults. <br /> The site is in the northwestern San Joaquin County Ground-Water Basin (California <br /> Department of Water Resources, 1988). Groundwater was encountered at approximately <br /> 87 feet below surface grade (bsg). <br /> ENVIRONMENTAL WORK <br /> According to information supplied by Teichert (LBME Corporation, October 1, 1988), <br /> Teichert removed two 1,000-gallon underground gasoline tanks in March 1987. The <br /> approximate locations of the present site features are shown on Plate 2. Laboratory <br /> analyses of soil samples collected from the base of the tank cavity, approximately 10 feet <br /> bsg, indicated that residual hydrocarbons were present. Analytical results of soil samples <br /> collected from the tank cavity are presented in Table 1. <br /> In July 1987, LBME Corporation of Sacramento, California, drilled three soil borings and <br /> installed one monitoring well in one of the borings (MW-1/BH-1). Results of analyses of <br /> soil samples collected between 20 and 35 feet below grade indicated that gasoline <br /> hydrocarbon concentrations(quantified as total petroleum hydrocarbons[TPH])ranged from <br /> below laboratory detection limits to 34 parts per million (ppm). Analytical results of soil <br /> samples collected from the borings are presented in Table 2 (LMBE, October 1, 1988). <br /> Hydrocarbons have not been identified in groundwater samples collected from the <br /> monitoring well with the exception of the initial sampling event,which immediately followed <br /> the well completion. According to LMBE, the hydrocarbons detected during that sampling <br /> event may have been due to contaminated equipment. Analytical results of groundwater <br /> samples collected from well MW-1 are presented in Table 3. <br /> 0504gtak/123009.01 2 <br />