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CONCLUSIONS AND RECOMMENDATIONS <br /> In summary, the soil conditions examined near the proposed septic disposal area for the <br /> new house on the Site were found to be suitable for a septic system. A satisfactory soil <br /> percolation rate of 17.8 min/in was observed in the shallow soil zone at the test location. <br /> The soil in the test location was found to be clay to a depth of 2.25 feet below ground <br /> surface, followed by clayey coarse sand with gravel to the full depth of the hole. <br /> Based on maps of recent aquifer levels, the depth of ground water is approximately 125 <br /> to 153 feet below ground surface. Ground water appears to flow generally to the north <br /> or northwest in the area at a rate of approximately 13 to 42 feet per mile. <br /> A water sample was collected from the domestic well on the Site. Nitrate was detected <br /> in the water sample at a concentration of 9.8 mg/L-N, just under the MCL of 10 mg/L-N. <br /> DBCP was not detected in the sample. <br /> Based on the methods and assumptions described, the nitrate loading calculation <br /> indicates that the existing and proposed future on-site septic drain field systems have <br /> the potential to cause a buildup of nitrate in the aquifer up to 13.1 mg/L-N, over the MCL <br /> of 10 mg/L-N. It should be remembered that the Hantzsche and Finnemore equation is <br /> a conservative method for determining potential impacts. Ground water is deep in the <br /> area and the clay soils may serve to limit the transportation of nitrate to the aquifer. <br /> Although Live Oak cannot make engineering recommendations, we are aware that the <br /> San Joaquin County Environmental Health Department often allows the use of standard <br /> septic systems with oversized septic tanks in cases where a 30 percent reduction would <br /> bring the nitrate loading under the MCL; the subject Site's nitrate loading result meets <br /> this criterion. <br /> Future septic system construction should follow the San Joaquin County On-Site <br /> Wastewater Treatment Systems Standards (2017) where applicable. In this area, septic <br /> systems typically utilize leach lines with seepage pits. <br /> LOGE 2614 Page 14 <br />