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Ground Water Information Depth and Gradient Live Oak reviewed ground-water elevation information available from the San Joaquin County Flood Control and Water Conservation District to determine the ground-water levels near the Site. Data from spring and fall of 2016 were the most recent available from this source. According to an analysis of these maps (Plates 5 and 6), ground- water elevation is approximately 10 to 30 feet above mean sea level. Ground water appears to flow to the northwest in the area at a rate of approximately 15 feet per mile. Given that the ground elevation of the Site is 115 to 120 feet above mean sea level, the depth to water below the Site is estimated to be approximately 85 to 110 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 (Plates 7 and 8). According to the nitrate map, 12 wells within a one-mile radius of the subject Site have been tested for nitrate. Nitrate was detected in nine wells at concentrations between 0.1 to 5.0 mg/L-N, and in two wells at concentrations from 5.0 to 10.0 mg/L-N; nitrate was not detected in the final well. Nine wells within a one-mile radius of the Site were tested for DBCP. DBCP was detected in one well at a concentration between 0.01 and 0.2 ug/L; no DBCP was detected in the other eight wells. On-Site Wells An irrigation well is located on the Site (Plate 3). No well records were identified for the Site from among the files of the San Joaquin County Environmental Health Department. Water Sample No water sample was collected from the irrigation well because Mr. Caton indicated the well water was being mixed with return water from the adjacent feedlot for land application; he stated that there was no spigot or sampling port where pure well water could be collected (personal communication, November 10, 2020). LOGE 20-54 Page 3