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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 16.7 min/in was observed at the test location. The <br />soil in the test location was found to be silty sand. <br />The depth of ground water based on recent aquifer levels is approximately 10 to 15 feet <br />below ground surface. The ground -water flow is to the north or northwest at a rate of <br />approximately two to three feet per mile. <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 will require an 8 -foot <br />separation from the bottom of the dispersal system to ground water, or other system <br />modification. <br />Two wells are located on the Site, a domestic well and an irrigation well. Because a <br />new domestic well will most likely be drilled for the project, no water sample was <br />collected as part of this investigation. Based on the maps reviewed, nitrate is present <br />above the MCL at several nearby wells; DBCP does not appear to be a concern for <br />wells in the area. <br />Based on the methods and assumptions described, the nitrate loading calculation <br />indicates that the use of an on-site septic tank and drain field system on the Site has the <br />potential to cause a buildup of nitrate in the aquifer up to 2.1 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 2142 Page 15 <br />