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CONCLUSIONS AND RECOMMENDATIONS In summary, the soil conditions examined near the existing septic system drain field were found to be suitable. A satisfactory soil percolation rate of 9.2 min/in was observed in the shallow soil zone at the test location. The depth of ground water based on recent aquifer levels is approximately 50 to 65 feet below ground surface. The ground-water flow is to the east, northeast, or southeast; the ground-water gradient beneath the Site could not be determined due to an unmapped area to the west. The highest recent ground-water levels for San Joaquin County were experienced in 1983 and 1999; however, depth to water in the Tracy area was not mapped for those years. Because of the percolation rate between 5.0 and 30.0 min/in encountered in the test hole, the San Joaquin County Environmental Health Department will require an eight- foot separation from the bottom of the dispersal system to ground water. Based on the anticipated depth to ground water, no modifications to standard, shallow septic systems should be required. No well is located on the Site; the Site receives water from community well CSA35. Live Oak reviewed publicly available information for CSA35 Well #1. According to CA Drinking Water Watch, this well was tested for nitrate in February of 2018 and 2019; nitrate was detected at 1 and 1.2 mg/L-N, respectively. DBCP was detected in February of 2016 (the most recent test result available) at 0.01 ug/L. 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 Based on a review of the San Joaquin County Environmental Health Department's map of nitrate detections in nearby wells, five wells within a half-mile radius of the subject Site have been tested for nitrate. Three of these wells were found to contain nitrate at a concentration greater than 10 mg/L-N, one contained nitrate at a concentration between 5.1 and 10 mg/L-N, and one contained nitrate at a concentration between 0.1 and 5.0 mg/L-N. According to the DBCP map, two wells within a half-mile radius of the Site have been tested for DBCP; no DBCP was detected in either well. Based on the methods and assumptions described, the nitrate loading calculation indicates that the use of on-site septic tanks and drain field systems on the Site has the potential to cause a buildup of nitrate in the aquifer up to 14.4 mg/L. However, based on the conservative nature of the calculation, depth to water, and clay soil present in the area, the actual impact to ground water may be considerably less. LOGE 20-01 Page 14