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I <br /> r I <br /> Mpona Market <br /> Vertical Groundwater Investigation&November 2003 Quarterly Report <br /> Page: 9 <br /> 1 <br />., For augured borings the soil samples were taken using a California Modified Split <br /> Spoon sampler with brass liners or with the use of a Simulprobe. A 140-pound <br /> hammer repeatedly falling 30 inches drove the sampler. The blow counts <br /> necessary to drive the sampler were recorded for each 6-inch interval to help <br /> evaluate the consistencies of the materials. <br /> The laboratory samples did not have headspace and were immediately sealed in <br /> their liners using aluminum foil lined plastic caps. The remaining sample was <br /> removed from its liner to be used as an aidlto the on-site geologist in logging the <br /> material at that depth. <br /> 1 <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 8021B with confirmation by method 8260. <br /> r. <br /> 2.3 Groundwater Sampling <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. GeoAnalytical Laboratories, Inc. in Modesto, <br /> California conducted the analyses. <br /> 7 <br /> 3.0 SITE CONDITIONS <br /> i <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 in 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 s l�tj and clays deposited at the interface of the lacustrine <br /> environment, which was fo�xtd in the center of the San Joaquin Basin. The upper <br /> unit at the site, which is described below, represents a basinward transgression of <br /> the coarser--grained alluvial fan sediments over the underlying finer-grained <br /> lacustrine sediments. A generalized hydrogeologic cross section is shown in figure <br /> 3. <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 /> consolidated} low plasticityY clay, silts, and poorly sorted silty sand. The <br />