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LOGE 1726: Phillips/Michael David NLS Addendum Page 9 <br /> September 20, 2017 <br /> • Table 5. Assumptions for Nitrate Loading Calculation <br /> Variable Value Units Description <br /> Q 4,779 gpd Effluent flow rate <br /> Nw 64.2 mg/L-N Effluent stream concentration <br /> A 52.95 acres Site area <br /> Nb 1.00 mg/L-N Concentration of rain <br /> d 0.25 constant Denitrification factor <br /> R 12.93 inches per year Deep percolation of rain water <br /> W 1.21 inches per year Uniform waste water loading (calculated) <br /> The details of the nitrate loading calculation are included in Plate 5. The results of the <br /> calculation are presented in the following table. <br /> Table S. Result of Nitrate Loading Calculation <br /> Variable Value Units Description <br /> • Long-term average concentration of percolating <br /> Nc 5.0 mg/L-N effluent <br /> The US EPA recommended MCL for nitrate in drinking water is 10 mg/L-N. Ina worst-case <br /> situation, the maximum buildup of nitrates from the use of septic systems in the aquifer is <br /> predicted to be 5.0 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 proposed development on the Site should not cause a buildup of <br /> nitrates in the aquifer above 10 mg/L-N. Because of the satisfactory result, no mitigation <br /> measures are recommended. <br /> • <br />