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Denitrification Reductions <br /> Denitrification is a process that occurs in the septic system drain field whereby certain <br /> bacteria oxidize the nitrate (NO3) in the waste water and release nitrogen gas (N2) to the <br /> 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 pf 25 percent was selected for the Site because of the <br /> fine-grained nature of the soils at the proposed septic system location. <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 6. Assumptions for Nitrate Loading Calculation <br /> Variable Value Units Description <br /> Q 634.8✓ gpd Effluent flow rate <br /> Nw 47.2 ✓ mg/L-N Effluent stream concentration <br /> A 5.0 acres Site area <br /> Nb 1.00 mg/L-N Concentration of rain <br /> d 0.25 constant Denitrification factor <br /> inches per <br /> R 6.58 year Deep percolation of rain water <br /> inches per <br /> W 1.71 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 /> LOGE 1325 Page 13 <br />