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L <br /> L June 12, 2006 <br /> NOA Project Number: E06061A <br /> concentration of 45 mg/L-N has been selected for residential uses for this calculation. It is <br /> estimated that commercial use will have higher concentrations of total nitrogen when compared to <br /> residential use. A conservative total nitrogen concentration of 85 mg/L-N has been selected for <br /> I km commercial uses for the purposes of this calculation. These values have been weighted based on the <br /> percentage of the total flow attributed to residential(89.6%) and commercial (10.4%) uses. <br /> Therefore,a total nitrogen concentration of 49 mg/L-N will be used for the nitrate loading <br /> calculation. <br /> 6. <br /> 3.4.2 DemtrMeation Estimate <br /> Denitrification is an important process which occurs within the leach field whereby certain bacteria <br /> utilize the oxygen in the nitrate (NO,) and release nitrogen gas (ND to the atmosphere. <br /> L 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,about 10 percent to 15 percent. <br /> 'r <br /> A standard denitrification factor of 25 percent was selected for the Site. <br /> 3.5 Nitrate Loading Scenario <br /> A nitrate loading scenario was performed to determine the impact from the proposed project. The <br /> 6' scenario utilizes the variables discussed previously which represent the estimated conditions and <br /> uses associated with this project. The following table presents a summary of the nitrate loading <br /> L calculation (Plate 11). <br /> Summary of Nitrate Mass Balance Analysis. <br /> Result Acres Average Daily Effluent Concen- Leachfield Deep Percolation of <br /> ' (Nc)* (A) Flow(Q) (Table 1) tration(Nw) Denitnfi- Rainfall(R) <br /> L I� (mg/L- cation (d) (Plate 10) .) <br /> K 41 <br /> ` 1.5 106.18 547 49 25% 5.31 <br /> * aximum contaminant leve L f trate in drinking water is 10 mg/L-N. <br /> L <br /> /3.6 Impact of Nitrate Loading to Nearby Water Sources <br /> The result of the nitrate loading b caof s tai ""'roposed use should not cause a buildup <br /> Lof nitrate in the ground water abo e t.0 mg/L-N over�ng term. According to the Hantzsche <br /> �n cnrt o tion and approach, ential for a buildup of nitrates in the ground <br /> water to 1.5 mg/L-N. <br /> L <br /> L <br /> 6 <br /> L '.044 <br /> 1 <br /> L <br />