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March 17;2005 NOA.Project Number: E05008A7 _ The presence of nitrates are not uncommon in shallow groundwater aquifers in San Joaquin County and other parts of the Central Valley. Nitrate in ground water occurs as a result of the application of fertilizers,livestock waste; and untreated septic tarik-waste. Nitrate is mobile and often: accumulatesin the shallow ground water zones. In the early 1900s, natural levels of nitrate in ground water were measured in forty-three (43) wells y = throughout the Sacramento Valley by Bryan (1923). It was thought that.groundwater at that time was close to."natural" conditions. Based on the work by Bryan, it is estimated that under"natural" conditions, ground water concentration containing nitrate is no more then about 13.5 mg/L-NO3 (3 mg/L--N). Areas having 24.75 mg/L-NO3(5.5 mg/L-N) or more are those in which nitrate .. .concentrations may,be increasing (Hull, 1984). F1 �DBCP is a nematocide-and-soil fumigant for vegetables and grapes:.It is thought to cause health _ problems consisting of kidney damage,liver damage,and cancer. The use of DBCP was - discontinued in 1979.The Environmental Protection Agency (EPA) set the maximum contaminant -=limit (MCL) at 0.2 parts per billion (ppb) because the EPA believes that given present technology is and resources, this is the lowest level to which watersystemscan reasonably be required to remove this contaminant should it occur in drinking water. 3 A.5 Well Water Sample Collection, Handling, and Transportation The samples were collected in a clean plastic container, then decanted into clean, glass vials. The - samples were then transported o__ice and remanded under chain of custody to Precision Enviro- Tech,.Stockton. 4.6 Chain of Custody.- The Chain of Custody document has been included in the appendix of this report. 5.0 SOIL PROFILE AND-GEOLOGIC INFORMATION The Site is depicted on,the Preliminary Geologic Map-of the San Francisco - Sanjose Cenozoic Deposits of the Tracy Quadrangle, California (1981), as within a region of Quaternary Fan deposits. g r The unit is one of gravel, sand silt and clay (Plate`3). The surface and near surface soils located at the Site are reported by:the San Joaquin County Soil Survey to be composed of the Capay clay, 0-2% slopes, E1 Solyo clay loam,;0-2% slopes, and the Vernalis clay loam, 0-20/o slopes (Plate 4) (USDA,`1992). Table 3 presents some selected properties of the soils: _