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L <br /> September 30,2007 <br /> NOA Project Number: E07147A <br /> Weighted Average for Total Nitrogen Concentration <br /> 6. <br /> 14,700gpd x 45 mg/L-N=661,500 <br /> 130gpd x 65 mg/L-N=Y�,450 <br /> 679,50/14,830gpd=45.85 mg/L-N y� <br /> L � <br /> ,/3.4.2 Denitrification Esdmate <br /> LDenitrification 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 /> Lpercent. Soilswitl� ' her clay content, moist soil conditions, high pH, and organic material <br /> denitrify by abo{x 3�perce t,and soils with high sand content and fast percolation rates are <br /> estimated to denitriwer rate, about 10 percent to 15 percent. <br /> I <br /> L <br /> A typical denitrification factorf 25 perce t was selected for the site due to the presence of the fine- <br /> grained soils encountered on site. <br /> 3.5 Nitrate Loading Scenario <br /> LA nitrate loading scenario was performed to determine the impact from the proposed project. The <br /> 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 /> calculation. <br /> � Table 3. <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) Denitrifi- Rainfall(R) <br /> (mg/L-N) d cation(d) (Plate 9) (in.) <br /> _Jgp21.2 22.61 14,830 45.85 2 25% 5.76 <br /> * Maximum contaminant level fbv6itrate in drinking water is 10 mg/L-N. <br /> Lv 3.6 Impact of Nitrate Loading to Nearby Water Sources <br /> The result of the nitrate loading balance indite710tng/L-N <br /> at the pro sed development is likely to cause.a <br /> L build up of nitrate in the ground water above over e long term <br /> Due to the relatively flat surface of the subjecpotential risk of surfacing effluent <br /> effecting surface water is expected to be minimal. <br /> L <br /> 6 <br /> '.-44 <br /> 60 <br />