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13 August 2019 AdvancedGeo <br /> AGE Project No. 19-4782 I:. i i v i ro n menta I <br /> Page 12 of 14 <br /> more sands and faster percolation rates (less moisture and clay content) denitrify only <br /> about 10 percent. <br /> A denitrification factor of 15 percent was selected for the calculation based on the silty <br /> sands existing at the site. <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 /> RESIDENTIAL: <br /> The Hantzsche / Finnemore (Nr) equation for residential home application: <br /> Nr = IxNw (1-d) + RxNb = (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: <br /> 450 gpd (proposed system) x 365 days of proposed operation = 450 x 365 days _ 7.48 <br /> gallons per cubic foot = 21,959 cubic feet of wastewater. Does not account for <br /> evapotranspiration likely to occur. <br /> NW = Total nitrogen concentration of wastewater at 45 mg/L-N based on the average <br /> discharge. Accounting for the loss of mg/L-N in the septic tank at 15% = 45-15%= 38.25 <br /> and the loss from the biomat at 10% 38.25 - 10% = 34.425 mg/L-N <br /> d = Fraction of nitrogen concentration removed from the wastewater due to denitrification <br /> within the soil (15 percent for silty sand type soils). <br /> R = Average rainfall rate per year: 11.50 inches. <br /> Nb = Background nitrate-nitrogen concentration of rainfall recharge, from wastewater <br /> influences. <br /> PROPOSED RESIDENCE CALCULATIONS: <br /> Nr = IxNw (1-d)+ RxNb _ (I+R) <br />