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April 29, 2005 NOA Project Number: E05040A i` 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 leakyunderground 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 Two wells exist on the site;one domestic well b the house and one agricultural well. According to Y g g Mr. Kowalski (personal communication April 25, 2005), the agricultural well will be abandoned. No well permits were found during file review at EHD on March 11, 2005.A water sample was taken from the well head of the domestic well by Mr. Conor McGee of our office on April 4,2005; see location on Plate 1. 4.4 Water Sample Constituents i FJ The water sample was analyzed for nitrate and DBCP. Nitrate was found at 13.7 ri g/L-NO3,below the maximum contaminant level (MCL) set by the US EPA of 45 mg/L-NO3. DBCP was not detected in the water sample. The analytical reports prepared by Precision Enviro-Tech can be found in the appendix of this report. i 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. i 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 groundwater at that time ' �4 was close to "natural' conditions. Based on the work by Bryan,it is estimated that under "naturae' - 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). F ' Though 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 Fj 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 �k 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. F1 5 � "044 0