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7B. CALCULATED NITRATE-NITROGEN LOADING NLS§3.4,3.5,3.6. The calculated nitrate-nitrogen impact to the soil and ultimately to the groundwater is difficult to determine due to the large number of variables involved and variables unknown at this time. These include: 1.) Impact from upgradient nitrate sources, 2.)Variability in wastewater flows, effluent nitrogen concentrations and dilution effects from stormwater recharge, 3.) Changes in groundwater directional flow and elevation,4.)And of significant importance is not only the denitrification potential of the indigenous soils, but equally important is the diminished nitrification potential within the soil environment. The small pore space within the high clay content soil significantly reduces oxygen content,thus impeding nitrification. HANTZSCHEIFINNEMORE EQUATION 1Nµ,(1 -d)+RNb 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 ac-ft 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 = Estimated Annual Rainfall Recharge in ac-ft Nb = Background nitrate-nitrogen concentration of rainfall recharge, exclusive of wastewater influences (ppm NO3-N). Values and Assumptions: I= 0.071 ac-ft Nw= 62 mg N/L d = Assume 25%due to the high percentage of clay soil(22%)found from 5 ft to 8 ft in depth that not only mitigates nitrification,but also promotes denitrification of nitrate molecules that may form in the stratum from 0 ft to 5 ft where lower clay concentrations occur. R = 5.70 ac-ft Nb= Assumed to be 0.1 ppm NO3-N 0.071 ac-ft(62 mg N/L) (1 -0.25)+(5.70 ac-ft x 0.1 mg/L) i Nr = (0.071 ac-ft+5.70 ac-ft) Nr = 0.67 ppm as nitrate-nitrogen (NO3-N) Page -7- Chesney Consulting