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C. Nitrate Loading Mass Balance A nitrate loading mass balance calculation is illustrated below, for the proposed project. The calculated or estimated nitrate impact to the soil and ultimately to the groundwater is extremely difficult to determine due to the number of variables involved. The Hantzsche/ Finnemore Equation is used to estimate the resultant average nitrate-nitrogen concentration in the effluent recharge water at a volume of 150 gpd, and a Total Nitrogen concentration of 112 ppm. This 112 ppnt concentration was arrived from septic tank effluent analysis from other similar-type. commercial projects. FIANf77S('HE/FINVE6fORE EQUATION IN„(1 - d) + RN,, Nr= (I+R) Where: Nr= Resultant average concentration of nitrate-nitrogen in recharge water-(ppm NO,-N) 1 = Volume rate of wastewater entering the soil averaged over the gross developed arca in inches pci >r Nw = Total nitrogen concentration of wastewater in N mg/'L (112 mg N'L/day) d = Fraction (01u)of nitrate-nitrogen loss due to denitrification in the soil R = Average recharge rate of rainfall -inches per yT(9.0 in.) N,= Background nitrate-nitrogen concentration of rainfall recharge, exclusive of wastewater influences (ppm NO;-N) Values and Assumptions: 150 aaWday x 260 work days/yr= 39,000 gals/yr= 5_214 cu ft W W/vr =11.4 in+yr 1 = 43,560 eu ft/Ac ft x 1.0 Ac x (1 f.112 in) Nw= 1 l2 mg NiL- 10%reduction in septic tank= 101 mg N/L d = 104o from biomat formation and 25% from clay soil under filter bed(66 mg N/L) N,, = Assumed to be 0.1 ppm NO;N 1.4 in%vr(101 me N1L) (1 -0.35) + (9 in/yr x 0.1 m¢/L) Nr _ (1.4 m/yr+9 in/yr) Nr = 8.9 ppm as NO,-N or 39.7 ppm as NO, The nitrate loading calculated for wastewater effluent recharge from the proposed facility is below the drinking water Maximum Contaminant Level(MCL) of 10 ppm NO3- N or 45 ppm NO,. The C,14y soil is projected to have at least a 25% denitrification potential. However, by taking advantage of a larger clay soil surface area under the chamber, this denitrification potential may be even higher, possibly 30%-35°/,. In addition, the calculated effluent recharge concentration above, does not account for nitrogen uptake by grass-type root structures that will absorb effluent at the infiltrator louvers. The nitrogen uptake concentration is estimated to be between 15% and 35% during favorable weather conditions when the interigir o.f thc.charribet:s is.wUrn. This should cause evaporation of the effluent off the soil/effluent interface and onto the louvers for grass root transpiration uptake. Consequently, there is potential for the recharge effluent to be approximately: I5% additional soil denitrification, 15% zone of saturation denitrification, 20% evapotranspiration 8.9 ppm =,4.5 ppm NO,-N. — Chesney Cunsufthig