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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 1.50 acres Site area <br /> Nb 0.17 mg/L-N Concentration of rain <br /> d 0.25 constant Denitrification factor <br /> R 3.23 inches per year Recharge rate of rainfall <br /> W 3.6 inches per year Uniform waste water loading (calculated) <br /> The details of the nitrate loading calculation are included in Plate 13. The results of the <br /> calculation are presented in the following table. <br /> Table 5. Result of Nitrate Loading Calculation <br /> Variable Value Units Description <br /> Nc 13.9 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 13.9 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 has the potential to cause <br /> a buildup of nitrates in the aquifer above 10 mg/L-N. It should be remembered that the <br /> Hantzsche and Finnemore equation is a conservative method for determining potential <br /> impacts, and actual nitrate loading experienced on the Site over time may be less than <br /> predicted. It is also worth noting that the Site is located in an agricultural area with few <br /> neighbors, so that the cumulative impact of development will be substantially less than <br /> in a more densely populated area. <br /> LOGE 2109 Page 12 <br />