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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 standard septic system utilizing leach lines and seepage <br />pits. A satisfactory soil percolation rate of 2.1 min/in was observed at the test location. <br />The soil in the test location was found to be silty sand. <br />The depth of ground water based on recent aquifer levels is approximately 135 to 165 <br />feet below ground surface. The ground-water flow is to the east-southeast at a rate of <br />approximately 11 to 21 feet per mile. <br />Because of the percolation rate between 1.0 and 5.0 min/in encountered in the test <br />hole, the San Joaquin County Environmental Health Department will require a 20-foot <br />separation from the bottom of the dispersal system to ground water, or other system <br />modification. Based on the predicted depth to water, no modifications to standard <br />systems should be necessary to meet this requirement. <br />No wells are located on the Site; no water sample was collected as part of this <br />investigation. Based on the maps reviewed, neither nitrate nor DBCP appear to be <br />common concerns for 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 1.8 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 2114 Page 14