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r 22 April 2009 AGE-NC-09-1683 Page 16 of 19 9.5. MASS BALANCE OF NITROGEN LOADING The EHD requires the user to considering all potential sources identified for wastewater generation. The EHD has required the maximumpotentially observable concentrations ofwaste water generated from the site to be evaluated for this model. Further, the EHD supports the use of Hantzsche/Finnemore, or other appropriate formula/model to calculated a mass of nitrogen loading. The Hantzsche/Finnemore (N) equation for commercial application: F Nr=,I x NR, (1-d)+R x Nb (I+R) Where, f Nr = The average concentration of nitrate-nitrogen in the recharged waste water parts per million of nitrate-nitrogen. I = Volume rate of wastewater entering the soil averaged over the gross developed area (4.5 acres) in inches per year. The total wastewater volume for proposed project will be - 750 gpd(total for multi-purpose room)x 36 days (maximum number of events per year) =27,000 gallons -42 gpd(total for warehouse) x 260 days (full-time employees)= 10,920 gallons 37,920 gallons 7.48 gallons per cubic foot= 5,070 cubic feet of wastewater. I Does not account for evapotranspiration likely to occur. NW =Total nitrogen concentration of wastewater(maximum anticipated)at 85 mg/L-N based on the average discharge. (Accounting for the loss of mg/L-N in the septic tank at 15%: 85mg/L-15%value= 72.25 mg/L and the loss from the biomat at 10%: 72.25 mg/L-10%value = 65 mg/L-N) d = Fraction of nitrogen concentration removed from the wastewater due to de-nitrification within the soil (an estimate of 25 percent for silty sands was used). R =Average rainfall rate per year: 17.28 inches and average deep infiltration: 6.59 inches. Nb = Background nitrate-nitrogen concentration of rainfall recharge, from wastewater influences. i Advanced GeoEnvironmental,Inc. E M