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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 4 and 5), ground water elevation is approximately three to five feet below mean sea level. Ground water flows down to the east at a rate of approximately eight to 11 feet per mile. Given that the ground elevation of the Site is approximately 14 feet above mean sea level, the depth to water below the Site is estimated to be approximately 17 to 19 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 6), four wells within a half-mile radius of the subject Site have been tested for nitrate, nitrate was detected in all four wells at concentrations between 0.1 and 5.0 mg/L-N. According to the DBCP map (Plate 7), two wells within a half-mile radius were tested for DBCP; it was not detected in either well. On-Site Wells One domestic well is currently located on the Site. Three well permits were identified for the Site from among the files of the San Joaquin County Environmental Health Department: • March 1984 permit for new domestic well. The well had a grout seal at a depth of 50 feet. • April 1984 permit for pump installation at domestic well. LOGE 20-48 Page 3