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Table 4. Assumptions for Nitrate Loading Calculation <br />Variable Value Units Description <br />300 gpd Effluent flow rate <br />Nw 35 mg/L-N Effluent stream concentration <br />A 1.72 acres Site area <br />Nb 0.2 mg/L-N Concentration of rain <br />0.35 constant Denitrification factor <br />9.42 inches per year Recharge rate of rainfall <br />2.3 inches per year Uniform waste water loading (calculated) <br />The details of the nitrate loading calculation are included in Plate 13. 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 4.7 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 4.7 mg/L-N. <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 proposed development on the Site should not cause a <br />buildup of nitrates in the aquifer above the maximum drinking water standard. <br />LOGE 20-59 Page 13