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• Live Oak reviewed the EHD's Water Well Data Table dated March 10, 2009 for nearby addresses that have been tested for nitrate and dibromochloropropane (DBCP), common ground-water contaminants in San Joaquin County. Two wells were identified within approximately three-quarters of a mile of the Site. Both of the wells had been tested for nitrate; it was detected in only one, at a concentration of 1.0 mg/L. Both of the wells had been tested for DBCP; it was not detected in either well. The Maximum Contaminant Level (MCL) set by the US EPA for nitrate as NO3 is 45 mg/L (10 mg/L-N); the MCL for DBCP is 0.2 µg/L. On-Site Wells A domestic well and an irrigation well serve the Site (Plate 3). One well permit, a June 1989 permit for new irrigation well, was identified for the Site at the San Joaquin County Environmental Health Department. This permit is included in Appendix'3. Water Sample Live Oak collected a water sample from the domestic well on the Site on March 22, 2018. The sample was analyzed for nitrate and dibromochloropropane (DBCP) per San Joaquin County Environmental Health Department policy. As required by the laboratory, the sample was collected in a plastic container and two glass vials for nitrate and DBCP analysis, respectively. A trip blank was also utilized. • The sample was placed on ice and transported under chain of custody to FGL Environmental, Stockton. Nitrate was detected in the sample at a concentration of 0.5 mg/L-N. Nitrate is commonly detected in shallow ground water aquifers of the Central Valley. Application of fertilizers, livestock waste, and untreated septic tank waste can all contribute to nitrate in ground water. Nitrate is mobile and tends to accumulate in shallow ground water zones. Based on work in the Sacramento Valley from the early 1900s, it is estimated that under "natural" conditions, ground water contains nitrate at concentrations no more then about 13.5 mg/L-NO3 (equivalent to 3.0 mg/L-N). Nitrate may be increasing in areas with concentrations of 24.75 mg/L-NO3 (5.5 mg/L-N) or more (Hull, 1984). The US EPA has set the Maximum Contaminant Level (MCL) for nitrate as N at 45 mg/L-NO3 (10 mg/L-N). DBCP is a nematocide and soil fumigant for vegetables and grapes. It is known to cause male reproductive effects and is classified as a probable human carcinogen. Most domestic use of DBCP was discontinued in 1977 through 1979. The US EPA set the MCL at 0.2 parts per billion (ppb, equivalent to µg/L) because it believes that, given present technology and resources, this is the lowest level to which water systems can • LOGE 1820 Page 4