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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 4 and 5), ground-water elevation is approximately zero to three feet below mean sea level; the Site is just beyond the mapped area in 2017, and the depth is extrapolated. Ground water appears to flow to the northeast at a rate of approximately 2 to 3 feet per mile. Given that the ground elevation of the Site is approximately 15 feet above mean sea level, the depth to water below the Site is estimated to be approximately 15 to 18 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 6 and 7). According to the maps, three wells within a half-mile radius of the subject Site have been tested for nitrate; nitrate was detected in one of these wells at a concentration between 0.1 and 5.0 mg/L-N, and in the other two wells at concentrations over 10 mg/L-N. According to the DBCP map, four wells within a half-mile radius of the Site have been tested for DBCP; no DBCP was detected in any of the wells. On-Site Wells A domestic well is located on the Site. One well permit was identified for the Site from among the files of the San Joaquin County Environmental Health Department. The permit, dated December 1974, was for a new domestic well with a grout seal at a depth of 50 feet. LOGE 2109 Page 3