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CONCLUSIONS AND RECOMMENDATIONS In summary, the soil conditions examined near the proposed septic system drain fields were found to be suitable. Satisfactory soil percolation rates of 9.6 and 5.8 min/in were observed in the shallow soil zone at the test locations. The depth of ground water based on recent aquifer levels is approximately nine to 17 feet below ground surface. The ground-water flow direction is to the north or southwest at a rate of approximately two to five feet per mile, depending on the season. The highest recent ground-water levels for the area were experienced in 1983 and 1999; it is extrapolated that ground water would have been present beneath the Site at approximately 10 feet below ground surface. Because the percolation rates encountered fall between 5.0 and 30 min/in, the San Joaquin County Environmental Health Department will require an eight-foot separation from the bottom of the dispersal systems to ground water, or mitigation by system design or enhancement. The San Joaquin County Environmental Health Department may require installation of a shallow/modified septic system to mitigate the shallow ground-water level. Live Oak collected two samples from the domestic well that will serve the new wine cellar. Nitrate was detected in the first sample at a concentration of 12.1 mg/L-N; it was detected in the second sample at a concentration of 7.8 mg/L-N. It is the opinion of Live Oak that the second water sample is more representative of typical water conditions on the Site because the well had not been operated for several months prior to the first sampling. DBCP was not detected in the water sample. As part of a previous investigation of the Site, Live Oak collected a water sample from the domestic well at the house in 2017. Nitrate was detected in that sample at a concentration of 6.6 mg/L- N; DBCP was not detected. The MCL for nitrate is 10 mg/L-N; the MCL for DBCP is 0.2 ug/L. Based on a review of San Joaquin County Environmental Health Department maps of nitrate and DBCP detections in nearby wells, it appears that two wells within a one-half mile radius of the Site have been tested for nitrate, and one well has been tested for DBCP. Nitrate was detected in two of the wells at concentrations between 0.1 and 5.0 mg/L-N, and in the third at a concentration between 5.1 and 10.0 mg/L-N. DBCP was detected in the well at a concentration between 0.01 and 0.2 µg/L. Based on the current project, the use of on-site septic tanks and drain field systems on the Site is not expected to cause a buildup of nitrate in the aquifer above 7.1 mg/L-N. This level falls below the US EPA drinking water recommendation of 10 mg/L-N. LOGE 1908 Page 15