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r7 And 4.) Of significant importance is not only the denitrification potential of the indigenous clays, but equally important is the diminished nitrification potential within the clay soil environment along with the lack of sufficient alkalinity. The extremely small pore space within the high clay content soil significantly reduces oxygen content,thus impeding nitrification. Although there are a number of formulas and equations to predict the inexact science of nitrate impact potential from septic systems,the Hantzsche/Finnemore Equation is used below to calculate the average concentration of nitrate-nitrogen in effluent recharge water from the proposed septic system. The calculations are based on the total areal loading basis of the entire 42-acre APN parcel, correlated with the annually projected wastewater flows of 156,000 gallons/yr: (600 gpd x 5 dpw=3,000 gpw x 52 wpy= 156,000 gpy). These two factors primarily estimate the average resultant concentration of nitrate-nitrogen in the recharge effluent. This concentration shall not exceed 10 ppm nitrate-nitrogen(45 ppm as nitrate). HANTZSCHEIFIAMMORE EQUATION IN,y(1 - d) +R Nb Nr= (I+R) Where: Nr = Resultant average concentration of nitrate-nitrogen in recharge water-(ppm NO3-N) I = Volume rate of wastewater entering the soil averaged over the gross developed area in inches per yr Nw = Total nitrogen concentration of wastewater in mg N/L d = Fraction(%)of nitrate-nitrogen combined loss in the high clay content soil due to: 1.) Prevention of nitrification and 2.)The denitrification of nitrate molecules that may form. R = Average recharge rate of rainfall- inches per yr NLS§3.2 Nb = Background nitrate-nitrogen concentration of rainfall recharge,exclusive of wastewater influences (ppm NO3-N)' Values and Assumptions: I= 156,000 gals=total WW/Yr=20,856 cu ft =0.13685 in/yr 42 Ac x 43,560 sq ft/Ac x(1 ft/12 in) Nw= 146 mg N/L d = At least 30%as referenced above,due to the high percentage of clay soil(33%)that not only mitigates nitrification,but also promotes denitrification of nitrate molecules that may form. R = 9.5 in/yr. Nb= Assumed to be 0.1 ppm NO3-N 0.13 685 in/yr(146 mg N/L) (1 -0.30)+(9.5 in/yr x 0.1 mgt) Nr = (0.13685 in/yr+9.5 in/yr) LNr5 ppm as nitrate-nitrogen(NO3 N), or 6.9 ppm as nitrate. Page -8- Chesney Consulting