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f B. 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 clays, but equally important is the diminished nitrification potential within the clay soil environment. The extremely small pore space within the high clay content soil significantly reduces oxygen content,thus impeding nitrification. The Hantzsche/Finnemore Formula is used below to predict the average resultant concentration of nitrate-nitrogen in effluent recharge water from the proposed wastewater treatment and management system. The calculations are based on a total areal loading basis previously referenced,correlated with the annually projected wastewater flows of 416,000 gpy. These two factors primarily estimate the average resultant concentration of nitrate-nitrogen in the recharge effluent. This concentration cannot exceed 10 ppm nitrate-nitrogen(45 ppm as nitrate). CALCULATED NITRATE-NITROGEN LOADING FROM THE COMBINED ON-SITE RESTROOMS FOR THE ENTIRE SUBJECT PARCEL: i HANTZSCHE/FINNEMORE EQUATION n!,,(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 Assum tip ons: r I=416.000 eals=total WW/yr=55.615 en It =0.0933 in/yr 164.28 Ac x 43,560 sq ft/Ac x(I ft/12 in) Nw= 62 mg N/L d = Assume 25%due to the high percentage of clay soil(280/6)throughout the soil profile 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 Page-7- Chesney Consulting