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w - November 30, 2007 NOA Project Number: E07188A 4.3 Water Sample Location According to Dave Silva there are two wells on site. One well is domestic and the other is a ! agricultural.A sample was taken from the faucet of the domestic well Q Februa 8__2007. 4.4 Water Sample Constituents The water sample was a zed for nitrate and DBCP. DBCP was not detected in the water sample. Nitrate was found� 7.2 /L-NO3i which is below the magnum contaminant level (MCL) of 45 fi mg/L-NO3 set by the United States EPA. The analyticaTreports prepared by FGL Environmental are attached. 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 on the condition of the aquifer. Essentially, the water sample concentration approximately indicates the contaminant concentration level of the aquifer from which the well is drawing. It is Neil O. Anderson and Associates' 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 F1regardless 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 early 1900s,natural levels of nitrate in ground water were measured in forty-three (43) wells k throughout the Sacramento Valle b Bryan 1923 . It was thought that ground water at that time g Y Y �' ( ) � was close to "natural" conditions. Based on the work by Bryan,it is estimated that under"natural" conditions, the ground water concentration of 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). 1 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 Fjdamage, 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) be6ause 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. �� 5 "044