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21 June 2019 AdvancedGeo <br /> AGE Project No. 19-4745 Environmental <br /> Page 12 of 14 <br /> 9.6. MASS BALANCE OF NITROGEN LOADING <br /> The EHD requires the user to consider all potential sources identified for wastewater <br /> generation. Further the EHD supports the use of Hantzsche/Finnemore, or other <br /> appropriate formula/model to calculate a mass of nitrogen loading. <br /> COMMERCIAL: <br /> The Hantzsche / Finnemore (Nr) equation for commercial application: <br /> Nr = I x Nw (1-d) + Rx Nb = (I+R) <br /> Definitions: <br /> Nr = The average concentration of nitrate-nitrogen in the recharged waste water parts per <br /> million of nitrate-nitrogen. <br /> I = Volume rate of wastewater entering the soil averaged over the gross developed area <br /> (acres) in inches per year. The total wastewater volume for proposed project will be 30 <br /> gpd x 365 days of proposed operation = 10,950 gallons _ 7.48 gallons per cubic foot = <br /> 1,464 cubic feet of wastewater. Does not account for evapotranspiration likely to occur. <br /> NW = Total nitrogen concentration of wastewater at 85 mg/L-N based on the average <br /> discharge. Accounting for the loss of mg/L-N in the septic tank at 15% = 85-15%= 72.25 <br /> and the loss from the biomat at 10% 72.25 - 10% = 65.025 mg/L-N <br /> d = Fraction of nitrogen concentration removed from the wastewater due to denitrification <br /> within the soil (20 percent for clay type soils). <br /> R = Average rainfall rate per year: 17.63 inches. <br /> Nb = Background nitrate-nitrogen concentration of rainfall recharge, from wastewater <br /> influences. <br /> MODULAR OFFICE UNIT CALCULATIONS: Nr = I x Nw (1-d)+ R x Nb - (I+R) <br /> Assumptions: <br /> = 10,950 gallons = 1,464 cubic feet wastewater _ [(3.01 acres x 43,560 feet2) - 12 <br /> inches] = 0.13 inches/year <br /> NW = 65.025 mg/L-N <br /> d = 20 percent denitrification <br /> R = 17.63 inches/year <br /> Nb = 0.1 milligram per liter <br />