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LOGE 1844: Farris NLS Addendum Page 7 <br /> March 5, 2019 <br /> Table 3. Assumptions for Nitrate Loading Calculation <br /> Variable Value Units Description <br /> Q 420 gpd Effluent flow rate <br /> Nw 35 mg/L-N Effluent stream concentration <br /> A 1.50 acres Site area <br /> Nb 1.00 mg/L-N Concentration of percolating recharge waters <br /> d 0.20 constant Denitrification factor <br /> R 9.2 inches per year Recharge rate of percolating waters" <br /> W 3.8 inches per year Uniform waste water loading (calculated) <br /> *See discussion and Table 2. <br /> The details of the nitrate loading calculation are included in Plate 1. The results of the <br /> calculation are presented in the following table. <br /> Table 4. Result of Nitrate Loading Calculation <br /> Variable Value Units Description <br /> Nc 8.8 mg/L-N Long-term average concentration of percolating <br /> effluent <br /> The US EPA recommended Maximum Contaminant Level (MCL) for nitrate in drinking <br /> water is 10 mg/L-N. In a worst-case situation, the maximum buildup of nitrates in the <br /> aquifer from the use of an on-site septic system is predicted to be 8.8 mg/L-N. <br /> Conclusions <br /> Because of the favorable result of the nitrate loading calculation, no nitrate mitigation is <br /> recommended at this time. <br />