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Rs ona Market <br /> .� p <br /> Subsurface Soil and Groundwater Investigation III Report <br /> Page 7 <br /> • removed from its liner to be used as an aide to the on-site geologist in logging the <br /> material at that depth <br /> All soil samples were delivered, under chain of custody, to GeoAnalytical <br /> Laboratories, an analytical laboratory licensed by the State of California for <br /> hazardous materials work The samples were analyzed for Total Petroleum <br /> Hydrocarbons (gasoline), BTX&E (Benzene, Toluene, Xylene, and Ethyl <br /> Benzene) and MTBE by method 8021 B with confirmation by method 8260 <br /> 2.3 Groundwater Sampling <br /> All sampling equipment, including the stainless steel Geoprobe® screen point, <br /> used by sampling personnel, was disassembled and steam cleaned prior to <br /> commencement of sampling The screen point was driven at least one foot ahead <br /> of the last soil sample and opened to allow water to flow into it Water samples <br /> were obtained through a disposable Teflon tube and pumped into the appropriate <br /> laboratory containers Water samples collected below the saturated zone in <br /> borings B-4 & B-6 were obtained with the use of a Simulprobe <br /> Groundwater samples were analyzed or extracted within 14 days according to <br /> . EPA methods and analyzed for Total Petroleum Hydrocarbons (gasoline), <br /> BTX&E (Benzene, Toluene, Xylene, and Ethyl Benzene) and the Oxygenated <br /> Compounds by Method 8260 GeoAnalytzcal Laboratones, Inc in Modesto, <br /> California conducted the analyses <br /> 3,0 SITE CONDITIONS <br /> 3.1 Site Geology & Groundwater Occurrence <br /> The site is underlain by interbedded fine to medium grained distal facies sediments <br /> of the Pleistocene Modesto Formation The Modesto Formation to the Ripon area <br /> was deposited in the distal portion of coalescing alluvial fans derived from the <br /> Sierra Nevada Mountains to the east In the distal portions of the fans, sandy <br /> sediments interfinger with silts and clays deposited at the interface of the lacustnne <br /> environment, which was found in the center of the San Joaquin Basin The upper <br /> unit at the site, which is described below, represents a basinward transgression of 1 <br /> the coarser grained alluvial fan sediments over the underlying finer grained <br /> lacustnne sediments A generalized geologic cross section is shown in figure 4 <br /> The upper 15 feet of sediments explored at the site consist of medium dense to <br /> dense, fine to medium, angular, arkosic sands A fine-grained unit is present from <br /> depths 21 to 30135 ft This unit consists of interbedded predominately moderately <br />