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A denitrification factor of 35 percent was selected for the Site because of the clay soil <br /> present at the percolation test location. <br /> Nitrate Loading Estimate <br /> A nitrate loading scenario was employed to determine the impact from the existing and <br /> proposed development to ground water. The scenario utilizes the variables discussed <br /> previously, which represent the estimated conditions and uses associated with this <br /> project. The following table summarizes the assumptions for the nitrate loading <br /> calculation for the Site, as presented in Plate 16. <br /> Table 4. Assumptions for Nitrate Loading Calculation <br /> Variable Value Units Description <br /> Q 400 gpd Effluent flow rate <br /> Nw 35 mg/L-N Effluent stream concentration <br /> A 1.03 acres Area <br /> Nb 0.103 mg/L-N Concentration of rain <br /> d 0.35 constant Denitrification factor <br /> R 3.91 inches per year Recharge rate of rainfall <br /> W 5.2 inches per year Uniform wastewater loading, calculated <br /> The details of the nitrate loading calculation are included in Plate 16. The result of the <br /> calculation is presented in the following table. - <br /> Table 5. Result of Nitrate Loading Calculation <br /> Variable Value Units Description <br /> Nc 13.1 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 13.1 mg/L-N. <br /> LOGE 2614 Page 12 <br />