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CONCLUSIONS AND RECOMMENDATIONS <br /> In summary, the soil conditions examined on the homesite parcel were found to be <br /> suitable. A satisfactory soil percolation rate of 8.06 min/in was observed in the shallow <br /> soil zone at the test location. The soil in the test areas was found to be silty clay and <br /> sandy silt. <br /> The depth of ground water based on recent aquifer levels is estimated to be less than <br /> 10 feet below ground surface. The ground-water flow beneath the Site is to the east at <br /> a rate of approximately 5 to 9 feet per mile. Ground water depth and flow direction in <br /> the Delta are highly dependent on seasonal pumping and irrigation. <br /> Because the percolation rate encountered falls between 5.0 and 30.0 min/in, the San <br /> Joaquin County Environmental Health Department will require an eight-foot separation <br /> from the bottom of any future dispersal system to ground water. No construction is <br /> planned. <br /> A water sample was collected from the main domestic well on the Site as part of this <br /> investigation. Nitrate was detected in the sample at a concentration of 2.0 mg/L-N, well <br /> under the MCL of 10 mg/L-N. DBCP was not detected in the sample; the MCL for <br /> DBCP is 0.2 ug/L. Based on a review of the San Joaquin County Environmental Health <br /> Department's maps of nitrate and DBCP detections in nearby wells, these chemicals do <br /> not appear to be a problem for nearby properties. <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 homesite <br /> parcel of the Site has the potential to cause a buildup of nitrate in the aquifer up to 7.9 <br /> mg/L-N, below the MCL of 10 mg/L-N. No nitrate mitigation is recommended. <br /> LOGE 20-12 Page 15 <br />