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%No,' <br /> L July 28, 2006 <br /> NOA Project Number: E06068A <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 /> DBCP was detected in the water sample at a level of 30 ug/L. DBC 1! is a nematocide and soil <br /> V fimmigant for vegetables ander ap es. It is thought to cause health problems consisting of kidney <br /> damage,liver damage, and cancer. The use of DBCP was discontinued in 1979. The Environmental <br /> Protection Agency (EPA) set the maximum contaminant limit (MCL) at .20 parts per billion (ppb) <br /> because the EPA believes that given present technology and resources, this is the lowest level to <br /> which water systems can reasonably be required to remove this contaminant should it occur in <br /> drinking water. <br /> ,/4.5 Well Water Sample Collection, Handling, and Transportation <br /> The nitrate sample was collected in a sterile plastic container, the DBCP sample was collected in two <br /> sterile glass vials. The samples were then transported on ice and remained under chain of custody to <br /> V FGL Environmental, 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 the Bellota Quadrangle as within the <br /> Quaternary Riverbank Formation. Quaternary Riverbank Formation (upper and middle members) <br /> these units are arkosic alluvium forming Mokelumne River terraces and alluvial fan; chiefly sand; <br /> �- probably glacial outwash lower fans;abundant volcanic detritus (Plate 7). <br /> The surface and near surface soils located at the Site are reported by the San Joaquin County Soil Survey <br /> r. to be composed of Bruella sandy loam,hard substratum, 0-2% slopes (Plate 8) (USDA, 1992). The <br /> following table presents some selected properties of these soils: <br /> 6 <br />