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E <br /> Wafer Sample <br /> A water sample was collected from the domestic well on the Site on December 3, 2009 <br /> by David Welch. The sample was to be analyzed for nitrate and dibromochloropropane <br /> (DBCP) per San Joaquin County Environmental Health Department policy. <br /> As required by the laboratory, the sample was collected in a plastic container and two <br /> glass vials for nitrate and DBCP analysis, respectively. A trip blank was also utilized_ <br /> The sample was pla on ice an ed un a in of custody to FGL <br /> Environmental, Stockto Results of the tests are forthcom� g. <br /> Nitrate is commonly detected in s a ow gr wa er aquifers of the Central Valley. <br /> Application of fertilizers, livestock waste, and untreated septic tank waste can all <br /> contribute to nitrate in ground water. Nitrate is mobile and tends to accumulate in <br /> shallow ground water zones. Based on work in the Sacramento Valley from the early <br /> 1900s, it is estimated that under "natural` conditions, ground water contains nitrate at <br /> concentrations no more then about 13.5 mg/L-NO3 (3 mglL-N)_ Nitrate may be <br /> increasing in areas with concentrations of 24.75 mg/L-NO3 (5.5 mg/L-N) or more (Hull, <br /> 1984). <br /> DBCP is a nematocide and soil fumigant for vegetables and grapes. It is known to <br /> cause male reproductive effects and is classified as a probable human carcinogen. <br /> Most domestic use of DBCP was discontinued in 1977 through 1979. The US EPA set <br /> the MCL at 0.2 parts per billion (ppb) because it believes that given present technology <br /> and resources, this is the lowest level to which water systems can reasonably be <br /> required to remove this contaminant should it occur in drinking water. The Maximum <br /> Contaminant Level Goal (MCLG) for DBCP is zero. <br /> Soil Profile and Geologic Information <br /> The Site is depicted on the Preliminary Geologic map of the Tracy Quadrangle, San <br /> Joaquin County, Califomia (Dibblee, 1981). The Site is depicted within a map unit of <br /> Quaternary alluvium from the Holocene epoch (Plate 7). <br /> The surface and near surface soils located at the Site are reported by the USDA Web <br /> Soil Survey to be composed of Capay clay, 0 to 2 percent slopes, and Stomar clay <br /> loam, 0 to 2 percent slopes (Plate 8) (USDA, 2009). The table below presents some <br /> selected properties of these soils: <br /> LOGE0916 Page 4 <br />