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Table 4. Assumptions for Nitrate Loading Calculation <br /> Variable Value Units Description <br /> Q 300 gpd Effluent flow rate <br /> Nw 35 mg/L-N Effluent stream concentration <br /> A 2.00 acres Site area <br /> Nb 0.136 mg/L-N Concentration of rain <br /> d 0.35 constant Denitrification factor <br /> R 8.41 inches per year Recharge rate of rainfall <br /> W 2.0 inches per year Uniform waste water loading (calculated) <br /> The details of the nitrate loading calculation are included in Plate 14. 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 4.5 mg/L-N Long-term average concentration of percolating effluent <br /> Based on the methods and assumptions described, the use of existing and proposed <br /> septic tanks and drain field systems on the Site yields a calculated buildup of nitrates in <br /> the aquifer up to 4.5 mg/L-N. <br /> The US EPA recommended MCL for nitrate in drinking water is 10 mg/L-N. The result of <br /> the nitrate loading calculation is well below 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 proposed development on the Site should not cause a buildup <br /> of nitrates in the aquifer over 10 mg/L-N. Because of the favorable result of the nitrate <br /> loading calculation, no nitrate mitigation is recommended at this time. <br /> LOGE 2245 Page 12 <br />