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San Joaquin County experienced its highest recent ground-water levels in spring of 1983 and 1999. Review of ground-water maps for these years (Plates 7 and 8) reveals that depth to water would have been approximately 35 feet during these times. 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 9), three wells within a half-mile radius of the subject Site have been tested for nitrate. Nitrate was detected in two of these wells at concentrations between 0.1 and 5.0 mg/L-N, and in the third well at a concentration greater than 10 mg/L-N. According to the DBCP map (Plate 10), three wells within a half-mile radius of the Site have been tested for DBCP; it was not detected in any of the wells. 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 According to Mr. Tacsion, one domestic well exists on the Site (Plate 3). No well permits for the Site address were identified from San Joaquin County Environmental Health Department records. Water Sample Live Oak collected a water sample from the domestic well on April 16, 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. 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 water sample at a concentration of 9.0 mg/L-N. DBCP was not detected in the water sample. The laboratory analytical results are attached as Appendix 5 of this report. LOGE 1917 Page 4