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CONCLUSIONS AND RECOMMENDATIONS <br /> In summary, the soil conditions examined near the proposed septic system drain field <br /> were found to be suitable for a septic system utilizing leach lines with seepage pits. A <br /> satisfactory soil percolation rate of 10.4 min/in was observed at the test location. The <br /> soils in the test location were found to be clay and clayey silt. <br /> The depth of ground water based on recent aquifer levels is approximately 41 to 44 feet <br /> below ground surface. The ground-water flow is to the northeast or east-northeast at a <br /> rate of approximately 4 to 5 feet per mile. <br /> Because of the percolation rate between 5.0 and 30.0 min/in encountered in the shallow <br /> test hole, the San Joaquin County Environmental Health Department will require an <br /> eight-foot separation from the bottom of the dispersal system to ground water. Based <br /> on the anticipated depth to ground water, no modifications to standard septic systems <br /> should be necessary to fulfill this requirement. <br /> A water sample was collected from the domestic well on the Site as part of this <br /> investigation. Nitrate was detected in the sample at a concentration of 5.8 mg/L-N, well <br /> below the MCL of 10 mg/L-N. DBCP was not detected in the sample. Based on maps <br /> reviewed, neither nitrate nor DBCP appears to be a problem in nearby wells. <br /> Based on the methods and assumptions described, the nitrate loading calculation <br /> indicates that the use of on-site septic tanks and drain field systems on the Site has the <br /> potential to cause a buildup of nitrate in the aquifer up to 14.4 mg/L, above the <br /> maximum drinking water standard of 10 mg/L-N. No evidence has been identified of <br /> nitrate impacts in the area, however, and the soil conditions are favorable for nitrate <br /> reduction. Based on the depth to ground water, clay soils present, and nitrate test <br /> results in the area, the actual nitrate impact to ground water beneath the Site may be <br /> considerably less than predicted, and it is the opinion of Live Oak that an engineered <br /> nitrate-mitigating septic system is not warranted in this location. A standard system <br /> utilizing leach lines with seepage pits is recommended. <br /> LOGE 2115 Page 14 <br />