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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 7.57 min/in was observed in the shallow soil <br /> zone at the test location. <br /> The depth of ground water based on recent aquifer levels is approximately 103 to 104 <br /> feet below ground surface. The ground-water flow beneath the Site is to the east or <br /> southeast at a rate of approximately 8 to 13 feet per mile. San Joaquin County <br /> experienced its highest recent ground-water levels in spring of 1983 and 1999; depth to <br /> water was approximately 70 feet at these times. <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 1.1 mg/L-N, well <br /> below the MCL of 10 mg/L-N. DBCP was detected in the sample at a concentration of <br /> 0.06 ug/L; the MCL for DBCP is 0.2 ug/L, and the MCL Goal is zero. <br /> Based on a review of San Joaquin County Environmental Health Department maps of <br /> nitrate and DBCP detections in nearby wells, it appears that one well within a half-mile <br /> radius of the subject Site has been tested for nitrate; it was detected in that well at a <br /> concentration between 0.1 and 5.0 mg/L-N. One well within one-half mile of the Site <br /> has been tested for DBCP; DBCP was detected in the tested well at a concentration <br /> between 0.01 and 0.2 ug /L. <br /> Based on the nitrate loading calculation, the use of on-site septic tanks and drain field <br /> systems on the Site is expected to cause a buildup of nitrate in the aquifer up to 11.1 <br /> mg/L-N. This level exceeds the US EPA drinking water recommendation of 10 mg/L-N. <br /> Because of the depth to ground water, soil type, test results from the domestic well, and <br /> conservative nature of the calculation, however, it is the professional opinion of Live <br /> Oak that effluent from an additional septic system on the subject Site is unlikely to result <br /> in a build-up of nitrate above the MCL in the ground water. <br /> LOGE 1942 Page 15 <br />