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Flood Control and Water Conservation District, 1983 and 1999); however, the Tracy <br /> area was not mapped during these years. <br /> Potential Ground Water Contamination Issues <br /> The Soil Suitability Study is not intended to be an investigation into ground-water <br /> contamination sources, and no such investigation was conducted. Many sources can <br /> contribute to ground water contamination, including leaking underground storage tanks, <br /> agricultural activities, dairies, septic systems, and storm water infiltration. Agricultural <br /> activities and the use of septic systems in the area are known ground water <br /> contamination sources with the potential to impact the Site. <br /> 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. According to the nitrate map (Plate 6), four wells <br /> within a half-mile radius of the subject Site have been tested for nitrate; it was detected <br /> in three at concentrations greater than 10.0 mg/L-N, and in the remaining well at a <br /> concentration between 5.1 and 10.0 mg/L-N. According to the DBCP map (Plate 7), two <br /> wells within one-half mile of the Site were tested for DBCP; no DBCP was detected in <br /> either well. The Maximum Contaminant Level (MCL) set by the US EPA for nitrate is 10 <br /> mg/L-N; the MCL for DBCP is 0.2 ug/L. <br /> The nearby land to the north of the Site is residential, while the land to the south is <br /> agricultural, including several orchards; it is likely that elevated nitrate levels in the area <br /> derive from fertilizer application on the agricultural properties as well as residential <br /> septic systems. <br /> On-Site Wells <br /> One domestic well is currently located on the Site. Five well permits were identified for <br /> the Site from among the files of the San Joaquin County Environmental Health <br /> Department: <br /> • August 2006 permit for replacement domestic well. The permit notes that the <br /> new well is 250 feet deep and has a 200-foot grout seal. <br /> • June 2007 permit for destruction of old well. <br /> • August 2007 permit for pump repair at domestic well. <br /> • August 2016 permit for pump replacement at domestic well. <br /> • October 2016 permit for new pump at domestic well. <br /> These permits have been included in Appendix 4 of this report. <br /> LOGE 20-19 Page 4 <br />