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u � LSeptember 9,2005 NOA Project Number: E05039B L 4.2 Potential Ground Water Contamination Issues L Identifying potential ground-water contamination sources was not part of the scope of work for the soil suitability study. A Surface and Subsurface Contamination Report addressed this issue (NOA, 2005). Please refer to this report for descriptions. Potential ground-water contamination can occur from a number of sources which often include leaky underground storage tanks,agricultural activities, dairies, septic systems,and storm water infiltration. Agricultural activities and the use of septic systems in the area should be considered potential ground-water contamination sources. 4.3 Water Sample Location One private well exists on the subject property. No permits were found during file review at EHD on August 23, 2005. One water sample was taken on August 15, 2005 by Ms. Nancy Rosulek from the domestic well of the subject property. L4.4 Water Sample Constituents The water sample was analyzed for nitrate and DBCP. DBCP was not detected in the water sample. pL Nitrate was found at 19.0 mg/L-NO3,well below the maximum contaminant level (MCL) set by the US EPA of 45 mg/L-NO3. The analytical reports prepared by 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 L 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 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' 9 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 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. 5 '-'04 1.