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F <br /> e Loading Mass Balanceoading mass balance calculation is described below for the proposed project.r estimated nitrate impact to the soil and ultimately to the groundwater is extremelyetermine due to the number of variables involved. The HantzschelFinnemorc <br /> used to estimate the resultant average nitrate-nitrogen concentration in the effluent <br /> argewater at a volume of 540 gpd, and a Total Nitrogen concentration of 112 ppm. This 112 <br /> ppm concentration was determined from septic tank effluent analysis from other similar-type, <br /> commercial projects. <br /> >i 1 <br /> LAC'H <br /> X F,/FIANEMORE EQ TA77ON F7 'g f t �\v <br /> 1 <br /> L&Ll..-d) -+ R �A <br /> Nr= (I+R) �. <br /> Where: � <br /> Nr= Resultant average concentration of nitrate-nitrogen in recharge water-(ppm NO,-N) 'V <br /> I = Volume rate of wastewater entering the soil averaged over the gross developed area in inches per yr <br /> Nw= Total nitrogen concentration of wastewater in N m 112 mg N/L'day) <br /> d = Fraction(% of nitrate-nitrogen loss duc to d sficafi in the soil <br /> R = Average recharge rate of rainfall -inches per (9.0 in.) <br /> Nb= Background nitrate-nitrogen concentration of ras all recharge,exclusive of wastewater influences <br /> (ppm NO,-N) <br /> Values and Assumptions: <br /> 540 gals/day x 365 days/w= 197 100 eals/yr=26,350 cu ft WW/yr = 1.9 in/yr <br /> I = 43,560 cu ft/Ac ft x 3.8 Ac x (1 fl/12 in) <br /> Nw= 112 mg N/L- 10%reduction in each septic tank=3 tanks=30%= 78 mg NIL <br /> d = 10% from biomat formation and 25% from clay soil under filter bed <br /> N,, = Assumed to be 0.1 ppm NO,N <br /> 1.9 in/yr(78 me NA,) (1 -0.35)+(9 in/yr x 0.1 me/L) <br /> Nr = (1.9 in/yr +-9 in/yr) <br /> Nr =; 8.9 Ppm as NO3-N or 39-6 pprn as NO3 <br /> The nitrate loading calculated for wastewater effluent recharge from the proposed ;ffpp"mMTN03-N), <br /> dge <br /> W!1p <br /> below the drinking water Maximum Contaminant Level (MCL) f 105 ppm NO,. e clay soil underlying the filter bed is projected to have at least a <br /> trification ential. However, by taking advantage of a high clay soil percentage throughout the <br /> soir e, this denitrification potential may be even higher, possibly 30°1-35%, In addition, the <br /> calculated effluent recharge concentration above does not account for nitrogen uptake by plant root <br /> structures that will absorb effluent at the Infiltrator Chamber louvers and from soil surrounding the <br /> Chambers. The nitrogen uptake concentration is estimated to be between 15% and 25% during <br /> favorable weather conditions when the interior of the chambers is warm. <br /> Page -10- / <br /> �r <br /> ----------------- <br /> Chesney Consulting <br />