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Table 7. Assumptions for Nitrate Loading Calculations, Parcel 2 <br />Variable <br />Value <br />Units <br />Description <br />Q (no development) <br />0 <br />gpd <br />Effluent flow rate <br />Q (two homes) <br />450 <br />gpd <br />Effluent flow rate <br />Nw <br />35 <br />mg/L-N <br />Effluent stream concentration <br />A <br />2.00 <br />acres <br />Site area <br />Nb <br />0.15 <br />mg/L-N <br />Concentration of rain <br />d <br />0.35 <br />constant <br />Denitrification factor <br />R <br />9.42 <br />inches per year <br />Recharge rate of rainfall <br />W (no development) <br />0.0 <br />inches per year <br />Uniform waste water loading (calculated) <br />W (two homes) <br />3.0 <br />inches per year <br />Uniform waste water loading (calculated) <br />The details of the nitrate loading calculations are included in Plates 14 through 16. The <br />results of the calculations are presented in the following table. <br />Table 8. Result of Nitrate Loading Calculation <br />Variable Value <br />Units <br />Description <br />Nc (Parcel 1) 2.3 <br />mg/L-N <br />Long-term average concentration of percolating effluent <br />Nc (Parcel 2, no <br />0.15 <br />mg/L-N <br />Long-term average concentration of percolating effluent, <br />development) <br />no development <br />Nc (Parcel 2, <br />5.6 <br />mg/L-N <br />Long-term average concentration of percolating effluent, <br />two houses) <br />two houses <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 2.3 mg/L-N for existing development on Parcel 1, <br />0.15 mg/L-N for no development on Parcel 2, and 5.6 mg/L-N for two houses on Parcel <br />2. In all three scenarios, the result of the nitrate loading estimate is well below <br />maximum drinking water standard. <br />LOGE 2150 Page 15 <br />