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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 50 to 60 feet above mean sea level. Ground water flows down to the northwest at a rate of approximately five to six feet per mile in the area northwest of the Site; the gradient for the Site itself cannot be calculated because it is at the edge of the map. Given that the ground elevation of the Site is approximately 135 feet above mean sea level, the depth to water below the Site is estimated to be approximately 75 to 85 feet. San Joaquin County experienced its highest recent ground-water levels in 1983 and 1999. Review of ground-water maps for spring of these years (Plates 7 and 8) reveals that depth to water would have been approximately 45 to 53 feet at these tjmes. 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), three wells within a one-mile radius of the subject Site have been tested for nitrate. Nitrate was detected in one well at a concentration between 0.1 and 5.0 mg/L-N, and in two wells at concentrations over 10 m/L-N. According to the DBCP map (Plate 10), one well within the same area was tested; DBCP was not detected in that well. 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. LOGE 1945 Page 3