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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 spring and fall of 2021 were the most recent available from this source. According to an analysis of these maps (Plates 5 and 6), ground water elevation near the Site is approximately zero to one foot above mean sea level, and ground water flows to the north in the general area at a rate of 1.5 to 2.5 feet per mile. Given that the ground elevation of the Site is approximately 39 to 40 feet above mean sea level, the depth to water below the Site is estimated to be approximately 38 to 40 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, seven wells within a one-mile radius of the subject Site have been tested for nitrate. Nitrate was detected at a concentration between 0.1 and 5.0 mg/L-N in two of the wells, and at concentrations between 5.1 and 10 mg/L-N in the other five wells. According to the DBCP map, five wells within a one-mile radius of the Site have been tested for DBCP. DBCP was detected in one well at a concentration over 0.2 µg/L; no DBCP was detected in the remaining four wells. On-Site Wells A domestic well is located on the Site (Plate 3). Two well permits were identified for the Site from among the files of the San Joaquin County Environmental Health Department: • July 1976 permit for new domestic well. The grout seal was placed 50 feet deep. The permit notes, "old well must be destroyed under permit"; it describes the old well as four inches in diameter and 30 feet deep. LOGE 2217 Page 3