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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 4.46 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 28 to 45 feet below ground surface. In the spring map reviewed, ground water flows down to the west at a rate of approximately ten feet per mile; the gradient could not be calculated for the fall map. 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 10 to 18 feet below ground surface. Because the percolation rate encountered falls between 1.0 and 5.0 min/in, the San Joaquin County Environmental Health Department will require a 20-foot separation from the bottom of the dispersal system to ground water. Based on depth to water in the area, no modifications to standard, shallow 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, one well within a half-mile radius of the subject Site has been tested for nitrate. Nitrate was detected in the well at a concentration between 0.1 and 5.0 mg/L-N. According to the DBCP map, one well within the same area was tested. DBCP was detected at a concentration over 0.2 µg/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 the method and assumptions described, the nitrate loading calculation indicates that the use of an on-site septic tank and drain field system on the Site has the potential to cause a buildup of nitrate in the aquifer of 11.5 mg/L-N, above the US EPA drinking water recommendation of 10 mg/L-N. However, based on the conservative nature of the calculation and low existing nitrate levels in ground water, it is the professional opinion of Live Oak that shallow septic effluent from the subject Site is unlikely to contribute significantly to a build-up of nitrate in the ground water. We believe the Site suitable for the use of a standard, shallow septic system utilizing leach lines or a filter bed for the current project. LOGE 1936 Page 12