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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 for a standard septic system utilizing leach lines and seepage pits. A satisfactory soil percolation rate of 5.43 min/in was observed in the deep soil zone at the test location. The soils in the test location were found to include strata of sand, silt, and clay. The percolation test is considered representative of soils within a 100-foot radius of the test location. Because of the parcel size and location of existing wells on adjacent parcels, Mr. and Mrs. Nienhuis obtained permission from Wayne Fox, REHS, Interim Director of the San Joaquin County Environmental Health Department, to perform the percolation testing and install the septic system less than 150 feet from their own and neighbors' wells. The new system will be at least 100 feet from all wells. Based on maps reviewed, ground water is anticipated to be encountered approximately 102 to 105 feet below ground surface at the Site. The ground-water gradient beneath the Site is to the northeast at a rate of approximately 10 to 11 feet per mile. Because of the percolation rate between 5.0 and 30.0 min/in encountered in the deep 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 septic systems should be required. No operational wells are located on the Site. No water sample was collected. 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 7.8 mg/L, less than the MCL of 10 mg/L-N. As a result, no nitrate mitigation is recommended. LOGE 20-41 Page 13