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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. A satisfactory soil percolation rate of 2.87 <br />min/in was observed in the shallow soil zone at the test location. The soil in the test <br />location was found to be sandy silt. <br />The depth of ground water based on recent aquifer levels is approximately 69 to 71 feet <br />below ground surface. The ground -water flow is to the northeast at a rate of <br />approximately 9 to 15 feet per mile in the vicinity of the Site. <br />The domestic well on the Site is not connected to a power supply at this time. No water <br />sample was collected as part of this investigation. Based on the map reviewed, DBCP <br />contamination appears to be a significant problem for wells in the area. San Joaquin <br />County Environmental Health Department will require that the domestic well be tested <br />for nitrate and DBCP as part of the project approval; if either contaminant is detected <br />above the MCL, a water filtration system or well deepening will be required. <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 12.9 mg/L, slightly above the <br />maximum drinking water standard of 10 mg/L-N. Based on the depth to ground water, <br />the proposed shallow filter bed septic system, and nitrate test results in the area, the <br />actual nitrate impact to ground water beneath the Site may be considerably less than <br />predicted, and the proposed filter bed system may be sufficiently protective of water <br />quality. The San Joaquin County Environmental Health Department determines septic <br />system requirements on a case-by-case basis. <br />LOGE 2145 Page 14 <br />