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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 28 to 38 feet below mean sea level; ground water flows down to the northeast at a rate of approximately eight feet per mile. Given that the ground elevation of the Site is approximately 55 feet above mean sea level, the depth to water below the Site is estimated to be approximately 83 to 93 feet. San Joaquin County experienced its highest recent ground-water levels in 1983 and 1999. Review of ground-water maps for spring of these (ears (Plates 7 and 8) reveals that depth to water would have been approximately 78 feet'in 1983 and 72 feet in 1999. 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 9), 11 wells within a half-mile radius of the subject Site have been tested for nitrate. Nitrate was detected in eight of these wells at concentrations between 0.1 and 5.0 mg/L-N, in two of the wells at a concentration between 5.1 and 10 mg/L-N, and in the last well at a concentration over 10 mg/L-N. According to the DBCP map (Plate 10), eight wells within a half-mile radius of the Site have been tested for DBCP; it was not detected in any of the wells. The Maximum Contaminant Level (MCL) set by the US EPA for nitrate is 10 mg/L-N; the MCL for DBCP is 0.2 ug/L. On-Site Wells A domestic well is currently located on the Site. One well permit was identified for the Site from among the files of the San Joaquin County Environmental Health Department. LOGE 1920 Page 3