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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 denitrification fact r of 20 percent s selected for the Site because of the moderately <br /> fine-grained nature o e soils. <br /> Nitrate Loadina_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 10. <br /> Table 6. Assumptions for Nitrate Loading Calculation <br /> Variable Value Units Description <br /> Q 641.6✓ gpd Effluent flow rate <br /> Nw 47.6 ✓ mg/L-N Effluent stream concentration <br /> .A 10.01 acres Site area <br /> Nb 1.00 ,/ mg/L-N Concentration of rain <br /> d 0.20 constant Denitrification factor <br /> inches per <br /> R 6.57 ✓ year <br /> Deep percolation of rain water <br /> inches per <br /> W 0.86 ✓ year Uniform waste water loading for calculation <br /> The details of the nitrate loading calculation are included in Plate 10. The results of the <br /> calculation are presented in the following table. <br /> LOGE1005 <br /> Page 12 <br /> f� <br /> 1 <br />