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C) n <br /> NITRATE IMPACT MITIGATION <br /> It is proposed to install a wastewater treatment system for this specific project that will lower the <br /> nitrate-nitrogen concentration to a maximum of 10 mg/L NO3-N. To predict the estimated final <br /> nitrate-nitrogen loading for the project,this concentration will be used in the <br /> Hantzsche/Finnemore Equation, as follows: <br /> INw(1 - d) +R N_b, <br /> Nr= (I +R) <br /> Where: <br /> Nr= Resultant average concentration of nitrate-nitrogen in recharge water- (ppm NO3-N) <br /> I = Volume rate of wastewater entering the soil averaged over the gross developed area in <br /> inches per yr <br /> Nw= Total nitrogen concentration of wastewater in mg NIL <br /> d = Fraction (%) of nitrate-nitrogen loss due to denitrification in the soil <br /> R = Average recharge rate of rainfall - inches per yr <br /> Nb= Background nitrate-nitrogen concentration of rainfall recharge, exclusive of wastewater <br /> influences (ppm NO3-N) <br /> i <br /> Values and Assumptions <br /> I = 375 g_alsld x 260 work d/yr= 97,500 gals=total WW/yr= 13,035 cu ft = 5.0 in. <br /> 31,631 sq ft <br /> Nw= 10 mg max NIL <br /> d = Assume 40% from shallow leachlines since effluent must pass through -6.0 ft clay soil <br /> R = 10 in/yr. However, 75% of total area covered w1 roofs and asphalt :. 2.5 in/yr. <br /> Nb= Assumed to be 0.1 ppm NO3-N <br /> 5.0 in/yr (10 mg N/L) I - 0.40 + 2.5 in/yr x 0.1 mg/L) <br /> Nr = (5.0 in/yr+ 2.5 in/yr) <br /> Nr = 4.0 ppm as nitrate-nitrogen(NO3-N) or 18.2 ppm as nitrate (NO3) <br /> In addition to this calculated reduction in nitrate-nitrogen loading by using a treatment system, <br /> further decrease in loading may occur by the use of leachfield landscaping. The percentage <br /> reduction may be on the order of 35%: <br /> 4.0 ppm NO3-N - 35% =2.6 ppm NO3-N <br /> -3- <br /> Va&y Ag Research <br />