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atmosphere. Due to the biologic processes in the shallow soils, nitrogen in the drain <br /> field will may undergo a reduction between 10 percent to 35 percent. Soils with higher <br /> clay content, moist soil conditions, high pH, and organic material denitrify by about 35 <br /> percent, and soils with high sand content and fast percolation rates tend to denitrify at a <br /> lower rate of about 10 percent. <br /> A typical denitrification factor of 25 percentr*as selected for the Site because of the <br /> relatively fine-grained nature of the Site soils. <br /> Nitrate Loading Estimate <br /> A nitrate loading scenario was employed to determine the impact from the proposed <br /> project to ground water. The scenario utilizes the variables discussed previously, which <br /> represent the estimated conditions and uses associated with this project. The following <br /> table presents a summary of the assumptions for the nitrate loading calculation for the <br /> Site, as presented in Plate 12. <br /> Table 5. Assumptions for Nitrate Loading Calculation <br /> Variable Value Units Description <br /> Q 35.7 gpd Effluent flow rate <br /> Nw 85.0 mg/L-N Effluent stream concentration <br /> N%I A 0.89 acres Site area <br /> Nb 1 .00 mg/L-N Concentration of rain <br /> d 0.25 constant Denitrification factor <br /> R 5.98 inches per year Deep percolation of rain water <br /> W 0.54 inches per year Uniform waste water loading for calculation <br /> The details of the nitrate loading calculation are included in Plate 12. The results of the <br /> calculation are presented in the following table. <br /> Table 6. Result of Nitrate Loading Calculation <br /> Variable Value Units Description <br /> \ Long-term average concentration of percolating <br /> Nc 6.19 n g/L-N effluent <br /> LOGE0914 Page 11 <br />