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09 August 2022 AdvancedGeo Project No. 22-6942 An Employee- Owned Company Page 13 of 16 -^" Z 9.6. MASS BALANCE OF NITROGEN LOADING The EHD requires the user to consider all potential sources identified for wastewater generation. Further, the EHD supports the use of Hantzsche/Finnemore or other appropriate formula/model to calculate a mass of nitrogen loading. RESIDENTIAL: The Hantzsche / Finnemore (Nr) equation for residential home application: Nr=IxNw(1-d)+RxNb=(I+R) Definitions: Nr = The average concentration of nitrate -nitrogen in the recharged wastewater parts per million of nitrate -nitrogen. I = Volume rate of wastewater entering the soil averaged over the gross developed area (acres) in inches per year. The total residential wastewater volume for the proposed project will be 200 gpd (existing system) x 365 days of proposed operation = 200 x 365 days - 7.48 gallons per cubic foot = 9,760 cubic feet of wastewater. Does not account for evapotranspiration likely to occur. NW = Total nitrogen concentration of wastewater at 45 mg/L-N based on the average discharge. d = Fraction of nitrogen concentration removed from the wastewater due to denitrification within the soil (25 percent for sandy loam soils). R = Estimated Deep percolation / average rainfall recharge rate per year: 2.99 inches. Nb = Background nitrate -nitrogen concentration of rainfall recharge: 1.0 mg/I. The Nb is an average value determined for San Joaquin County by the EHD. EXISTING RESIDENTIAL CALCULATIONS: Nr=IxNw(1-d)+RxNb_(I+R) Assumptions: I = 73,000 gallons = 9,760 cubic feet wastewater - [(10 acres x 43,560 feet2) - 12 inches] = 9,760 - 36,300 = 0.27 inches/year NW = 34.425 mg/L-N d = 25 percent denitrification R = 2.99 inches/year Nb = 1.0 milligram per liter Nr = [0.27 inches/year x 45 mg/L-N (1-0.25)] + (2.99 inches/year x 1.0 milligram per liter)