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CONCLUSIONS AND RECOMMENDATIONS <br /> In summary, the soil conditions examined near the proposed septic disposal areas for <br /> the new homes on the Site were found to be suitable for a standard septic system. A <br /> satisfactory soil percolation rate of 12.5 min/in was observed in the deep soil zone at the <br /> test location. The soil in the test location was found to be gravelly silt to 1 foot below <br /> ground surface, followed by silty gravel with sand to approximately 9 feet, followed by <br /> sandy gravel with silt to approximately 15 feet, followed by gray clay to approximately <br /> 20 feet, followed by sandy silt to the full depth of the hole (24.87 feet). <br /> Based on maps of recent aquifer levels, the depth of ground water is approximately 160 <br /> to 170 feet or more below ground surface. Ground water appears to flow generally to <br /> the west-southwest in the area at a rate of approximately 14 feet per mile for the fall of <br /> 2024. The gradient could not be calculated for the Spring of 2025 because the Site falls <br /> beyond the mapped area. <br /> No wells are located on the Site; no ground-water sample was collected for this <br /> investigation. <br /> Based on the methods and assumptions described, the nitrate loading calculation <br /> indicates that the proposed on-site septic drain field systems on the Site have the <br /> potential to cause a buildup of nitrate in the aquifer up to 5.6 mg/L-N, below the MCL of <br /> 10 mg/L-N. Because of the favorable result of the calculation, no nitrate mitigation is <br /> recommended at this time. <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 2622 Page 13 <br />