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Table 4. Assumptions for Nitrate Loading Calculation <br />Variable Value Units Description <br />Q 450 gpd Effluent flow rate <br />Nw <br />35 <br />mg/L-N <br />Effluent stream concentration <br />A <br />3.68 <br />acres <br />Site area <br />Nb <br />0.136 <br />mg/L-N <br />Concentration of rain <br />d <br />0.25 <br />constant <br />Denitrification factor <br />R <br />8.41 <br />inches per year <br />Recharge rate of rainfall <br />W 1.6 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 4.4 mg/L-N Long-term average concentration of percolating effluent <br />Based on the method and assumptions described, the existing and proposed homes on <br />the Site result in a calculated buildup of nitrates in the aquifer up to 4.4 mg/L-N. <br />The US EPA recommended MCL for nitrate in drinking water is 10 mg/L-N. The results <br />of the nitrate loading calculation are 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 results of the nitrate loading <br />estimates indicate that the proposed development on the Site should not cause a <br />buildup of nitrates in the aquifer over 10 mg/L-N. Because of the favorable result of the <br />nitrate loading calculation, no nitrate mitigation is recommended at this time. <br />LOGE 2210 Page 12 <br />