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Table 6. Result of Nitrate Loading Calculation <br /> Variable Value Units Description <br /> Nc 3.3 mg/L-N Long-term average concentration of percolating effluent <br /> The US EPA recommended MCL for nitrate in drinking water is 10 mg/L-N. In a worst- <br /> case situation, the maximum buildup of nitrates in the aquifer from the use of septic <br /> systems on the Site is predicted to be 3.3 mg/L-N. The result of the nitrate loading <br /> estimate is well below the maximum drinking water standard. <br /> Discussion of Nitrate Loading Results <br /> Total Nitrate Impact <br /> Based on the method and assumptions described, the result of the nitrate loading <br /> estimate indicates that the existing and proposed development on the Site should not <br /> cause a buildup of nitrates in the aquifer above 10 mg/L-N. <br /> The Hantzsche and Finnemore equation is a conservative method for determining <br /> potential impacts, and actual nitrate loading experienced on the Site over time may be <br /> less than predicted. Indeed, the clay soils on the Site will likely restrict downward <br /> percolation of the effluent and provide greater nitrate reduction than is indicated by this <br /> calculation. The requirement by San Joaquin County Environmental Health Department <br /> that the calculation use rainfall and evapotranspiration data to determine ground-water <br /> recharge is particularly conservative, as it does not include consideration of recharge <br /> from irrigation water or surface water sources. <br /> Because of the positive result of the nitrate loading calculation, no nitrate mitigation is <br /> recommended. <br /> LOGE 1843 Page 13 <br />