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03 June 2021 <br />Project No. 21-6431 <br />Page 13 of 15 <br />N . . <br />An Employee -Owned Company <br />controlled by waste concentrations, soil type, annual rainfall, pH of the soils, total organic <br />concentration of the soil (TOC) and exposure time to nitrogen. The soils with a high or <br />moderate clay content, higher organic content, high pH, and adequate soil moisture <br />denitrify the concentrations by approximately 30 percent and less desirable soils with <br />more sands and faster percolation rates (less moisture and clay content) denitrify only <br />about 10 percent. A denitrification factor of 30 percent was selected for the calculation <br />based on the clay and loam soil 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 wastewater 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 />250 gpd (existing system) + 150 gpd (proposed system) x 365 days of proposed operation <br />= 400 x 365 days - 7.48 gallons per cubic foot = 19,518 cubic feet of wastewater. Does <br />not account for 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 (30 percent for clay and loamy soils). <br />R = Estimated Deep percolation / average rainfall recharge rate per year: 3.20 inches. <br />Nb = Background nitrate -nitrogen concentration of rainfall recharge: 1.0 mg/I. The Nb is <br />an average value determined for San Joaquin County by the EHD. <br />