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L March 24,2005 NOA Project Number: E05025A ` The presence of nitrates is not uncommon in shallow ground water 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 tank waste. Nitrate is mobile and often accumulates in the shallow ground water zones. In the early 1900s,natural levels of nitrate in ground water were measured in forty-three (43) wells throughout the Sacramento Valley by Bryan (1923). It was thought that ground water 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). 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 and resources, this is the lowest level to which water systems can reasonably be required to remove this contaminant should it occur in drinking water. 6. 4.5 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 on ice and remanded under chain of custody to Precision Enviro- Tech,Stockton. ` 4.6 Chain of Custody The Chain of Custody document s have been included in the appendix of this report. 5.0 SOIL PROFILE AND GEOLOGIC INFORMATION The Site is depicted on the Geologic Map of the San Francisco-San Jose Quadrangle,as within a region of Quaternary Modesto Formation. Quaternary Modesto Formation is a unit of arkosic alluvium forming Mokelumne River terraces and alluvial fan;chiefly sand with minor gravel and silt;probably glacial outwash (Plate 7). The surface and near surface soils located at the Site are reported by the San Joaquin County Soil Survey to be composed of the Delhi fine sand, 0-5% slopes,Delhi loamy sand,0-2% slopes,Timor loamy I sand, 0-2% slopes,Tinnin loamy coarse sand,0-2%slopes and the Veritas fine sandy loam, 0-2% slopes (Plate 8). Table 5 presents some selected properties of the soils: 6