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' September <br /> 30, 2007 <br /> NOA Pto)ect Number: E07141A <br /> 3.4.2 Denitrification Estimate <br /> Denitrification is an important process which occurs within the leach field whereby certain bacteria <br /> utilize the oxygen in the nitrate (NO3) and release nitrogen gas (N� to the atmosphere. <br /> Denitrification is expressed as a percentage, and the normally accepted range is 10 percent to 35 <br /> percent. Soils with higher clay content, moist soil conditions, high pH, and organic material_ <br /> denitrify by about 35 percent, and soils with high sand content and fast percolation rates are <br /> estimated to denitrify at a lower rate, ab6 ercent o 15 percent. <br /> A typical denitrification factor f 25 pet en was selected _ <br /> � p cted for the site becaUSe of the fine grrained <br /> soils that exist at the si <br /> 3.5 Nitrate Loading Scenario <br /> { A nitrate loading scenario was performed to determine the impact from the proposed project. The <br /> F scenario utilizes the variables discussed previously which represent the estimated conditions <br /> Fj <br /> and <br /> uses associated with this project. The following table presents a summary of the nitrate ioadin variables for each parcel. <br /> Table 2. <br /> Sof Nitrate Mass Balance. <br /> esult Effluent <br /> Acres ( * Average Concen- Leachfield Deep Percolation <br /> Parcel Use Parcel Daily Flow tration Denitrifi- of Rainfall(R) <br /> (A) (mg/L-N) (Q)(gpd) (Nw) cation(d) (Plate 9)(in.) <br /> 420 gpd <br /> (mg/L-N) <br /> Commcrci 1 � r <br /> I \, (Parcel 1) 1 4.03 10.0' 431 gpd MAX 80 mg/1.,N <br /> 2 2.42 8.4 <br /> 3 2.01 9.6 <br /> 4 2.02 9.5 . <br /> 5 01 9.6 � / 11tesidcn ' 420 gpd 45 mg/I—N 25% 7.95 in. <br /> (Parcels 2-9 6 2.01 9.6 / <br /> 7 2. 0 9.6 i <br /> 8 9.3 <br /> 9 2.08 9.3 <br /> * Maximum coma level(MCL) for nitrate in drinking water is 10 mg/L-N. <br /> zuz <br /> 6 <br /> 24�� <br />