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July 11, 2007 NOA Project Number: E07094A 4.2 Potential Ground Water Contamination Issues Identifying potential ground-water contamination sources was not part of the scope of work for the soil suitability study. Potential ground-water contamination can occur from a number of sources which often include j leaky underground storage tanks,agricultural activities, dairies, septic systems,and storm water infiltration. Any past agricultural activities and the present use of septic systems in the area should be considered potential ground-water contamination sources. F14.3 Water Sample Location Three well permits were found for the subject property address during file review at EHD. The first permit was issued to Virginia Clouse in August of 1975.The permit was for the installation of a domestic well. The second permit was issued to "Etat" and was for the installation of a submersible pump in February of 1985. The third permit was issued for the installation of a domestic well in September of 1993. A water sample was taken from a faucet of the domestic well near the center of the property by Mr. Jessen Welch of our office on June 6, 2007 (Plate 1). r F14.4 Water Sample Constituents The water sample was analyzed for nitrate_and DBCP. DBCP was not detected in the water sample. Nitrate was found at 1.0 mg/L-NO3,well below the maximum contaminant level (MCL) of 45 F! mg/L-NO3 set by the United States EPA. The analytical reports prepared by FGL Environmental can be found in the appendix of this report. FiWell 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 F' aquifer. Essentially,the water sample concentration approximately indicates the constituent concentration level of the aquifer from which the well is drawing. Itis 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 i fertilizers,livestock waste, and untreated septic tank waste. Nitrate is mobile and often accumulates in the shallow ground water zones. 5 i