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atmosphere. Due to the biologic processes in the shallow soils, nitrogen in the drain <br /> field may undergo a reduction between 10 percent to 35 percent. Soils with higher clay <br /> content, moist soil conditions, high pH, and organic material denitrify by about 35 <br /> percent, and soils with high sand content tend to denitrify at a lower rate of about 10 <br /> percent. <br /> A denitrification factor of 35 percent was selected for the Site because of the clayey soil <br /> present at the percolation test location. <br /> Nitrate Loading Estimate <br /> A nitrate loading scenario was employed to determine the impact from the proposed <br /> project (Parcel 1) to ground water. The scenario utilizes the variables discussed <br /> previously, which represent the estimated conditions and uses associated with this <br /> project. The following table presents a summary of the assumptions for the nitrate <br /> loading calculation for the Site, as presented in Plate 15. <br /> Table 3. Assumptions for Nitrate Loading Calculation, Parcel 1 <br /> Variable Value Units Description <br /> Q 200 gpd Effluent flow rate <br /> Nw 35 mg/L-N Effluent stream concentration <br /> A 4.5 acres Site area, Parcel 1 <br /> Nb 0.3 mg/L-N Concentration of rain <br /> d 0.35 constant Denitrification factor <br /> R 4.04 inches per year Recharge rate of rainfall <br /> W 0.6 inches per year Uniform waste water loading (calculated), both parcels <br /> The details of the nitrate loading calculation are included in Plate 15. The results of the <br /> calculation are presented in the following table. <br /> Table 5. Result of Nitrate Loading Calculations <br /> Variable Value Units Description <br /> Nc (Parcel 1) 3.2 mg/L-N Long-term average concentration of percolating effluent <br /> LOGE 20-17 Page 11 <br />