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` June 14,2005 <br /> NOA Project Number: E05066A <br /> In the early 1900s,natural levels of nitrate in ground water were measured in forty-three (43) wells <br /> ` throughout the Sacramento Valley by Bryan (1923). It was thought that ground water at that time <br /> was close to "natural' conditions. Based on the work by Bryan,it is estimated that under"natural" <br /> conditions,ground water concentration containing nitrate is no more then about 13.5 mg/L-NO3 (3 <br /> ` mg/L-N). Areas having 24.75 mg/L-NO3 (5.5 mg/L-N) or more are those in which nitrate <br /> concentrations may be increasing(Hull, 1984). <br /> ` Though DBCP was not found in the water sample, DBCP is a nematocide and soil fumigant for <br /> vegetables and grapes. It is thought to cause health problems consisting of kidney damage, liver <br /> damage, and cancer. The use of DBCP was discontinued in 1979.The Environmental Protection <br /> his. Agency (EPA) set the maximum contaminant limit (MCL) at 0.2 parts per billion (ppb) because the <br /> EPA believes that given present technology and resources,this is the lowest level to which water <br /> L systems can reasonably be required to remove this contaminant should it occur in drinking water. <br /> 1x'4.5 Well Water Sample Collection, Handling, and Transportation <br /> The sample for nitrate was collected in a clean plastic container, the sample for DBCP was collected <br /> in two clean glass vials. The samples were then transported on ice and remanded under chain of <br /> custody to Precision Enviro-Tech, Stockton. <br /> /4.6 Chain of Custody <br /> The Chain of Custody document has been included in the appendix of this report. <br /> /5.0 SOIL PROFILE AND GEOLOGIC INFORMATION <br /> The Site is depicted on the USGS Preliminary Geologic Map of Cenozoic Deposits of the Bellota <br /> ` Quadrangle, California as within the Quaternary Modesto Formation,upper member. This unit is an <br /> Arkosic alluvium forming Mokelumne River terraces and alluvial fan;chiefly sand with minor gravel <br /> and silt;probably glacial outwash (Plate 7). <br /> The surface and near surface soils located at the Site are reported by the San Joaquin County Soil Survey <br /> to be composed of Tokay fine sandy loam, 0-2% slopes (Plate 8) (USDA, 1992). Table 3 presents <br /> some selected properties of the soil: <br /> i <br /> 6 <br />