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CONCLUSIONS AND RECOMMENDATIONS In summary, the soil conditions near the proposed septic system drain field were found to be suitable. A satisfactory soil percolation rate of 8.33 min/was observed in the shallow soil zone at the percolation test location. The depth of ground water based on recent aquifer levels is approximately 83 to 93 feet below ground surface. Ground water flows down to the northeast at a rate of approximately eight feet per mile. The highest recent ground-water levels for the area were experienced in spring of 1983 and 1999; at these times, ground water would have been present at approximately 70 to 75 feet below ground surface. Because the percolation rate encountered falls 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 system to ground water. Based on depth to water in the area, no modifications to standard systems should be required. No wells are located on the Site; no water sample was collected as part of this investigation. Based on a review of the San Joaquin County Environmental Health Department map of nitrate detections in nearby wells, six wells within a half-mile radius of the subject Site have been tested for nitrate. Nitrate was detected in four of these wells at concentrations between 0.1 and 5.0 mg/L-N, in one at a concentration between 5.1 and 10 mg/L-N, and in one at a concentration over 10 mg/L-N. According to the DBCP map, 11 wells within a one-mile radius of the Site were tested. DBCP was not detected in ten of those wells; it was detected in the one remaining well at a concentration between 0.01 and 0.2 ug/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 4.7 mg/L-N. This level falls well below the US EPA drinking water recommendation of 10 mg/L-N. We believe the Site suitable for the use of standard septic systems utilizing leach lines and seepage pits. Based on the satisfactory result of the nitrate loading calculation, no nitrate mitigation is recommended for the current project. LOGE 1929 Page 12