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According to the DBCP map (Plate 7), three wells within a half-mile radius of the Site <br /> have been tested for DBCP; no DBCP was detected in any of the wells. The Maximum <br /> Contaminant Level (MCL) set by the US EPA for nitrate is 10 mg/L-N; the MCL for <br /> DBCP is 0.2 ug/L. <br /> The Site is located in a residential neighborhood surrounded by orchards and <br /> agricultural land. Immediately to the north of the Site is the former Trinkle and Boys <br /> crop dusting facility, a listed site due to former underground fuel storage tanks and <br /> complaints regarding chemical handling practices. That property received a "no further <br /> action" letter from the Central Valley Regional Water Quality Control Board in 2012 and <br /> has been developed as a school. <br /> On-Site Wells <br /> One domestic well is currently located on the Site. No well permits were identified for <br /> the Site from among the files of the San Joaquin County Environmental Health <br /> Department. <br /> Water Sample <br /> Live Oak collected a water sample from the domestic well on the Site on September 2, <br /> 2020. The sample was analyzed for nitrate and dibromochloropropane (DBCP) per San <br /> Joaquin County Environmental Health Department policy. <br /> As required by the laboratory, the sample was collected in a plastic container and two <br /> glass vials for nitrate and DBCP analysis, respectively. Trip blanks were also utilized. <br /> The sample was placed on ice and transported under chain of custody to FGL <br /> Environmental, Stockton. <br /> Nitrate was detected in the sample at a concentration of 6.6 mg/L-N. DBCP was not <br /> detected in the water sample. The laboratory analytical results are attached as <br /> Appendix 5 of this report. <br /> Nitrate is commonly detected in shallow ground water aquifers of the Central Valley. <br /> Application of fertilizers, livestock waste, and untreated septic tank waste can all <br /> contribute to nitrate in ground water. Nitrate is mobile and tends to accumulate in <br /> shallow ground water zones. Based on work in the Sacramento Valley from the early <br /> 1900s, it is estimated that under "natural" conditions, ground water contains nitrate at <br /> concentrations no more then about 3 mg/L-N. Nitrate may be increasing in areas with <br /> concentrations of 5.5 mg/L-N or more (Hull, 1984). The US EPA has set the Maximum <br /> Contaminant Level (MCL) for nitrate at 10 mg/L-N. <br /> Although nitrate is a naturally-occurring compound necessary for plant growth, it can <br /> cause health problems when present at high levels in drinking water. The most <br /> LOGE 20-42 Page 4 <br />