SR0080810 SSNL - Laserfiche WebLink

Home Browse Search

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 34 feet to 44 feet above mean sea level; the ground- water flow beneath the Site is to the north or northeast at a rate of approximately six to 13 feet per mile. Given that the ground elevation of the Site is approximately 72 to 74 feet above mean sea level, the depth to water below the Site is estimated to be approximately 28 to 40 feet. San Joaquin County experienced its highest recent ground-water levels in 1987 and 1999. Maps of ground-water levels for these years were reviewed for this study (San Joaquin County Flood Control and Water Conservation District); however, the Tracy area was not mapped. 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; it was detected in two at concentrations between 0.1 and 5.0 mg/L-N, and in the other two at concentrations between 5.1 and 10.0 mg/L-N. According to the DBCP map (Plate 7), three wells within a one-half mile radius of the Site were tested for DBCP; no DBCP was 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. LOGE 1925 Page 3