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August 31, 2006 NOA Project Number: E06091A I l 1 4.4 Water Sample Constituents F The water sample was analyzed for nitrate and DBCP. DBCP was not detected in the water sample. r] Nitrate was found at 161 mg/L-NO3, above the maximum contaminant level (MCL) of 45 mg/U. NO3 set by the United States EPA. The analytical reports prepared by FGL Environmental can be found in the appendix of this report. F Well construction, seals, age and depth of the well screens may play significant part in assessing the levels of Nitrate and DBCP in various aquifers. Without knowing specific details regarding well construction and condition,it would be difficult to accurately comment of the condition of the aquifer. Essentially, the water sample concentration approximately indicates the constituent concentration level of the aquifer from which the well is drawing. It is Neil O. Anderson and Associate's opinion that,in general, near surface aquifers are more likely to have elevated concentrations of Nitrate and DBCP than the deeper aquifers. However the contaminant concentration of one aquifer cannot give any indication as to the concentrations of any other aquifer regardless of proximity. 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 earl 1900s natural levels of nitrate in ground water were measured in forty-three 43 wells y � ry ( ) 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 was not found 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. 4.5 Well Water Sample Collection, Handling, and Transportation The sample for nitrate was collected in a sterile plastic container, the sample for DBCP was collected in two sterile glass vials. The samples were then transported on ice and remained under chain of custody to FGL Environmental, Stockton. 5