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CONCLUSIONS AND RECOMMENDATIONS In summary, the soil conditions examined near the proposed septic disposal area for the new house on the Site were found to be suitable for a septic system. A satisfactory soil percolation rate of 7.81 min/in was observed at the test location. The soil in the test location was found to be silty, fine sand. Based on maps of recent aquifer levels, the depth of ground water is approximately 35 to 40 feet below ground surface. Ground water flows generally to the northeast in the area at a rate of approximately 6 feet per mile. Because of the percolation rate between 5.0 and 30.0 min/in encountered in the test hole, the San Joaquin County Environmental Health Department will require an 8-foot separation from the bottom of the dispersal system to ground water, unless mitigated by system design or enhancement. Given the estimated depth to water, no modification to septic systems should be necessary to comply with this requirement. A water sample was collected from the domestic well on the Site. Nitrate was detected in the water sample at a concentration of 6.5 mg/L-N. DBCP was not detected. Based on the methods and assumptions described, the nitrate loading calculation indicates that the septic drain fields from the existing and proposed houses on the Site have the potential to cause a buildup of nitrate in the aquifer up to 11.2 mg/L-N, slightly over the MCL of 10 mg/L-N. It should be remembered that the Hantzsche and Finnemore equation is a conservative method for determining potential impacts. A significant separation will exist between the bottom of the septic leach field and first ground water, and the on-site domestic well and nearby wells are not exhibiting nitrate impacts over the MCL despite existing development in the area. Consequently, the actual nitrate loading experienced on the Site over time may be less than predicted. Although Live Oak cannot make engineering recommendations, we are aware that the San Joaquin County Environmental Health Department often allows the use of standard septic systems with oversized septic tanks in cases where a 30 percent reduction would bring the nitrate loading under the MCL; the subject Site's nitrate loading result meets this criterion. Any future septic system construction should follow the San Joaquin County On-Site Wastewater Treatment Systems Standards (2017) where applicable. In this area, only septic systems utilizing leach lines, filter beds, or leach lines with shallow sumps are typically permitted. LOGE 2618 Page 14