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LOGE 1516: Stonum Vineyards NLS Addendum Page 7 <br /> August 11, 2015 <br /> Table 4. Assumptions for Nitrate Loading Calculation <br /> Variable Value Units Description <br /> Q 525.4 gpd Effluent flow rate <br /> Nw 46.9 mg/L-N Effluent stream concentration <br /> A 16.00 acres Site area <br /> Nb 1.00 mg/L-N Concentration of rain <br /> d 0.15 constant Denitrification factor <br /> R 6.58 inches per year Deep percolation of rain water <br /> W 0.44 inches per year Uniform waste water loading for calculation <br /> The details of the nitrate loading calculation are included on the attached page. The results of <br /> the calculation are presented in the following table. <br /> Table 5. Result of Nitrate Loading Calculation <br /> Variable Value Units Description <br /> Long-term average concentration of percolating <br /> Nc 3.44 mg/L-N effluent <br /> The US EPA recommended MCL for nitrate in drinking water is 10 mg/L-N. In a worst-case <br /> situation, the maximum buildup of nitrates from the use of septic systems in the aquifer is <br /> predicted to be 3.44 mg/L-N. The result of the nitrate loading estimate is below the maximum <br /> drinking water standard. <br /> Discussion of Nitrate Loading Results <br /> Total Nitrate Impact <br /> Based on the method and assumptions described, the result of the nitrate loading estimate <br /> indicates that the existing and potential future residences and proposed development on the <br /> Site should not cause a buildup of nitrates in the aquifer above 10 mg/L-N. Because of the <br /> satisfactory result, no mitigation measures are warranted. <br />