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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 the fall of 2017 and the spring of 2018 were the most recent available from this source. According to an analysis of these maps (Plates 5 and 6), ground-water elevation is approximately 35 to 40 feet below mean sea level. Ground water appears to flow to the northeast at a rate of approximately 11 to 24 feet per mile. Given that the ground elevation of the Site is approximately 38 feet above mean sea level, the depth to water below the Site is estimated to be approximately 73 to 78 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, four wells within a one-mile radius of the subject Site have been tested for nitrate. Three of these wells were found to contain nitrate at concentrations between 0.1 and 5.0 mg/L; nitrate was detected at a concentration between 5.1 and 10 mg/L-N in the final well. According to the DBCP map, six wells within a two-mile radius of the Site have been tested for DBCP. DBCP was detected in three of the wells at concentrations between 0.01 and 0.2 µg/L; no DBCP was detected in the other three wells. On-Site Wells A domestic well is located on the Site (Plate 2). Three well permits were identified for the Site from among the files of the San Joaquin County Environmental Health Department: • September 1990 permit for pump installation at domestic well. The well depth is listed as 176 feet. LOGE 2118 Page 3