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L �..� L January 24,2005 NOA Project Number: E04158A Methods 300.0 and 504.2,respectively. Nitrate was detected at a concentration of 17.1 mg/L-NO3i which is below the maximum contaminant level (MCL) of 45 mg/L-NO3 set by the California Department of Health Services. DBCP was not detected in the water sample. The laboartory analytical report sheets from Precision Enviro-Tech can be found in the appendix of this report. 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. 6. 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). h DBCP is a nematocide and soil fumigant for vegetables and grapes. It is thought to cause health Lproblems 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 i limit (MCL) at 0.2 parts per billion (ppb) because the EPA believes that given present technology yand resources,this is the lowest level to which water systems can reasonably be required to remove this contaminant should it occur in drinking water. 4.5 Well Water Sample Collection, Handling,and Transportation The exterior tap on the permanent residential structure was run wide-open for at least 10 minutes prior to collecting the water samples. The flow was then reduced and samples were collected directly into appropriate sample containers (one new plastic quart container,and one new 40 milliliter glass vial with HCL preservative). The samples were then transported on ice under proper chain of Lcustody to Precision Enviro-Tech, Stockton. L4.6 Chain of Custody Chain of Custody document for samples collected on is included in the appendix of this report. 5.0 SOIL PROFILE AND GEOLOGIC INFORMATION According to the Geologic Map of the San Francisco -San Jose Quadrangle, California(1991), the Site is Lunderlain by the Quaternary Riverbank Formation which is described as weathered reddish gravel, sand,and silt forming clearly recognizable alluvial terraces and fans (Plate 7). 1LThe surface and near surface soils located at the Site are reported by the to consist of the Madera 6 "04 u L