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Table 3. Assumptions for Nitrate Loading Calculation <br /> Variable Value Units Description <br /> Q 400 gpd Effluent flow rate, (2) 3-bedroom houses <br /> Q 450 gpd Effluent flow rate, 3-bedroom house and 4-bedroom <br /> house <br /> Nw 35 mg/L-N Effluent stream concentration <br /> A 1.50 acres Site area <br /> Nb 0.30 mg/L-N Concentration of rain <br /> d 0.35 constant Denitrification factor <br /> R 2.25 inches per year Recharge rate of rainfall <br /> W 3.6 inches per year Uniform waste water loading (calculated), (2) 3-bedroom <br /> houses <br /> W 4.0 inches per year Uniform waste water loading (calculated), 3-bedroom <br /> house and 4-bedroom house <br /> The details of the nitrate loading calculations are included in Plates 13 and 14. The <br /> results of the calculations are presented in the following table. <br /> Table 4. Result of Nitrate Loading Calculations <br /> Variable Value Units Description <br /> Long-term average concentration of percolating effluent, <br /> Nc 14.1 mg/L-N (2) 3-bedroom houses <br /> Long-term average concentration of percolating effluent, <br /> Nc 14.7 mg/L-N 3-bedroom house and 4-bedroom house <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 14.1 mg/L-N for two three-bedroom houses and <br /> 14.7 mg/L-N for a three-bedroom house and a four-bedroom house. In both cases, the <br /> result of the nitrate loading estimate exceeds the maximum drinking water standard. <br /> LOGE 2106 Page 12 <br />