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L LJune 12, 2006 NOA Project Number: E06061A /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 4 accumulates in the shallow ground water zones. 1. /n the early 1900s,natural levels of nitrate in ground water were measured in 43 wells throughout 'L 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). 6. ✓DBCP was not detected in the water sample. 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. r ✓4.5 Well Water Sample Collection, Handling, and Transportation Each water sample for nitrate was collected in a sterile plastic container,and each sample for DBCP was collected in two sterile glass vials. The samples were then transported on ice and under chain of custody to FGL Environmental, Stockton, California.. L /4.6 Chain of Custody The Chain of Custody documents have been included in the appendix of this report Y 5.0 SOIL PROFILE AND GEOLOGIC INFORMATION 1. The Site is depicted on the map Cenozoic Deposits of the BellotaQuadrangle(USGS 1979), as within a region of Holocene alluvium and Modesto Formation upper member. The Holocene alluvium consists of channel and levee deposits. The Modesto Formation upper member unit consists of arkosic alluvium forming Mokelumne River terraces and alluvial fan;chiefly sand with minor gravel Land silt;probably glacial outwash (Plate 7). JThe surface and near surface soils located at the Site are reported by the San Joaquin County Soil Sunxey I to be composed of Acampo sandy loam, 0 to 2 percent slopes, Columbia fine sandy loam, drained, 0 L to 2 percent slopes,Columbia fine sandy loam,partially drained,0 to 2 percent slopes, occasionally flooded, Kingdon fine sandy loam,0 to 2 percent slopes,and Tokay fine sandy loam,0 to 2 percent slopes (Plate 8). The following table presents some selected properties of the soils: V 6 L