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F1March 11, 2005 _ NOA Project Number. E04159A 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 Y 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 F! be considered potential ground-water contamination sources. 1/ 4.3 'Water Sample Location One domestic well exists on the Sitelate 2d parcel 1. A sample was taken by Mrs. �' 2) proposed p Rebecca Haskett of our office on February 10, 2005, at the head of the domestic well. No well permits were found during file review at EHD on January 6, 2005 for the address of 13299 p g J � North Curry Avenue. `X4.4 Water Sample Constituents The water sample was analyzed for nitrate and DBCP. found at 5.82 m /L-NO , below the maximum contaminant level (MCL) set by the US EPA of 45 mg/L-NO.. 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. 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 throughout the Sacramento Valley by Bryan (1923). It was thought that ground water at that time Fill was close to "natural" conditions. Based on the work by Bryan,it is estimated that under"natural" conditions,ground water concentration containing nittate 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 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 F. 11