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February 10, 2005 <br /> NOA Project Number: E05001A <br /> 3.5 Nitrate Loading Scenario <br /> A 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 for each parcel. <br /> Table 3. <br /> T Summa of Nitrate Mass-Balance Analysis. <br /> FJPlate Result Acres Average Daily Effluent Concentration Leachfield Deep Percolation of <br /> (Nc)* (A) -Flow(Q) (Nw)(mg/L-N) Denitrifi- Rainfall(R) <br /> (mg/L-N) (gpd) cation(d) (Plate 9) (in.) <br /> 10 28� 28 � -1.2 1190 45 10% 6.1 S <br /> * Maximum contaminant level(MCL) for nitrate in drinking water is 10 mg/L-N. <br /> 3.6 Impact of Nitrate Loading to Nearby Water Sources <br /> Based on.the method and assumptions described,in addition to the geologic setting, there is a <br /> possibility the proposed project, utilizing a standard septic system,will cause a build up of nitrate in <br /> the ground water above 10 mg/L-N over the long term. <br /> III F Due to the flat nature of the site and permeable soils, there is little potential of effluent ever spilling <br /> onto neighboring properties or waterways. <br />' 4.0 DISCUSSION OF NITRATE LOADING RESULTS <br /> 4.1 Total Nitrate Impact <br /> f <br /> Based on the method and assumptions described, the result of the nitrate loading balance indicates <br /> that the proposed development on the proposed parcels may cause a build up of nitrate in the,,`-_,', <br /> ground water above 10 mg/L-N over the long term. The calculated Nc value is 28 mg/L-b�is 2.8 ) <br /> times the drinking water standard. The cause of this buildup is the relatively small acreage©f'the r <br /> site, the high evapotranspiration rates of the site (less percolation of rain to dilute the percolating <br /> effluent over the long term) and the projected effluent generated from the facility. <br /> 4.2 Methods of Mitigation <br /> To mitigate the percolating nitrate, a small waste water treatment system such as the Orenco <br /> AdvanTex or equivalent could be utilized in Mode 3 optimized to remove total nitrogen in the waste <br /> water. Our office could provide you with more information and costs regarding the engineered <br /> septic systems. <br /> 6 <br /> f <br />