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Two common ground-water contaminants in San Joaquin County are nitrate and <br /> dibromochloropropane (DBCP). Live Oak reviewed the San Joaquin County <br /> Environmental Health Department's maps of Nitrate — Land Use Data and DBCP— Land <br /> Use Data dated February 20, 2019 (Plates 9 and 10). According to the nitrate map, <br /> nine wells within a one-mile radius of the subject Site have been tested for nitrate; <br /> nitrate was detected in eight of the wells at a concentration between 0.1 and 5.0 mg/L- <br /> N, and in the final well at a concentration between 5.1 and 10.0 mg/L-N. According to <br /> the DBCP map, seven wells within a one-mile radius of the Site have been tested for <br /> DBCP; no DBCP was detected in any of the wells. <br /> Three dairies are located within a third of a mile of the Site; however, based on the <br /> nitrate map reviewed, the dairies do not appear to have caused an elevation of nitrate <br /> levels in the area above the MCL. <br /> On-Site Wells <br /> A domestic well is located on the Site. <br /> One well permit was identified for the Site from among the files of the San Joaquin <br /> County Environmental Health Department. The permit, dated August 1977, was for the <br /> construction of a new domestic well with a grout seal at 56 feet. This permit has been <br /> included in Appendix 4. <br /> Water Sample <br /> Live Oak collected a water sample from the domestic well on the Site on May 18, 2020. <br /> 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 1.6 mg/L-N. No DBCP was <br /> detected in the sample. The laboratory analytical results are attached as Appendix 5 of <br /> 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 /> LOGE 20-20 Page 4 <br />