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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 or a filter bed. A <br /> satisfactory soil percolation rate of 10.0 min/in was observed at the test location. The <br /> soil in the test location was found to be peat. <br /> Ground water was encountered at 6.3 to 7.5 feet below ground surface in a test hole <br /> drilled adjacent to the percolation test hole. The ground-water flow direction could not <br /> be determined. Ground-water depth and flow direction in the Delta are controlled by <br /> island pumping and should be expected to fluctuate. <br /> Because of the percolation rate between 5.0 and 30.0 min/in encountered in the test <br /> hole, the San Joaquin County Environmental Health Department may require an 8-foot <br /> separation from the bottom of the dispersal system to ground water, or other system <br /> modification. It should be noted that Delta soils are highly organic and are known to be <br /> favorable for nitrogen reduction in shallow septic leach fields; this consideration should <br /> be taken into account when determining the system requirements. <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 0.2 mg/L-N, well <br /> below the MCL of 10 mg/L-N. DBCP was not detected in the sample. <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 1.1 mg/L, well below the <br /> maximum drinking water standard of 10 mg/L-N. Because of the favorable result of the <br /> nitrate loading calculation, no nitrate mitigation is recommended at this time. <br /> LOGE 2110 Page 14 <br />