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Given that the ground elevation of the Site is approximately 60 feet above mean sea level, the depth to water below the Site is estimated to be approximately 78 to 80 feet. San Joaquin County experienced its highest recent ground-water levels in 1983 and 1999. Review of ground-water maps for spring of these years (Plates 6 and 7) reveals that depth to water would have been approximately 60 feet. Potential Ground Water Contamination Issues The Soil Suitability Study is not intended to be an investigation into ground-water contamination sources, and no such investigation was conducted. Many sources can contribute to ground water contamination, including leaking underground storage tanks, agricultural activities, dairies, septic systems, and storm water infiltration. Agricultural activities and the use of septic systems in the area are known ground water contamination sources with the potential to impact the Site. Two common ground-water contaminants in San Joaquin County are nitrate and dibromochloropropane (DBCP). Live Oak reviewed the San Joaquin County Environmental Health Department's maps of Nitrate — Land Use Data and DBCP— Land Use Data dated February 20, 2019. According to the nitrate map (Plate 8), four wells within a half-mile radius of the subject Site have been tested for nitrate. Nitrate was detected in three of these wells at concentrations between 0.1 and 5.0 mg/L-N, and in the fourth at a concentration between 5.1 and 10 mg/L-N. According to the DBCP map (Plate 9), four wells within a half-mile radius of the Site have been tested for DBCP; it was detected in all four of the wells at concentrations over 0.2 ug/L. The Maximum Contaminant Level (MCL) set by the US EPA for nitrate is 10 mg/L-N; the MCL for DBCP is 0.2 ug/L. On-Site Wells A domestic well is currently located on the Site. One well permit was identified for the Site from among the files of the San Joaquin County Environmental Health Department. The permit, dated October 2016, is for a new domestic well 290 feet deep with a 200- foot grout seal; a redraw of the well location and a well log are also included. The permit has been included in Appendix 4 of this report. Water Sample Live Oak collected a water sample from the domestic well on the Site on May 1, 2019. 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. Trip blanks were also utilized. LOGE 1923 Page 3