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30 March 2022 <br />Project No. 22-6800 <br />Page 13 of 15 <br />AdvancedGeo <br />An Employyeee•Owned Company <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 loamy soils). <br />R = Estimated Deep percolation / average rainfall recharge rate per year: 2.67 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 />EXISTING AND PROPOSED HOME CALCULATIONS: <br />Nr=IxNw(1-d)+RxNb=(I+R) <br />Assumptions: <br />I = 146,000 gallons = 19,519 cubic feet wastewater - [(2.09 acres x 43,560 feet2) _ 12 <br />inches] = 19,519 _ 7,587 = 2.57 inches/year <br />NW = 34.425 mg/L-N <br />d = 25 percent denitrification <br />R = 2.67 inches/year <br />Nb = 1.0 milligram per liter <br />Nr = [2.57 inches/year x 34.425 mg/L-N (1-0.30)] + (2.67 inches/year x 1.0 milligram per <br />liter) _ (2.57 inches/year + 2.67 inches/year) <br />Nr=64.60=5.24=12.33 <br />Nr = 12.33 ppm nitrogen (NO3_N) <br />9.7. IMPACT OF NITROGEN LOADING FROM SITE PROJECT TO <br />DOWNGRADIENT WATER SOURCES <br />The recharging of groundwater is the most likely potential feature that could impact future <br />nitrogen loading. Since the subject property is flat, AGI does not anticipate percolating <br />effluent will affect any nearby water sources. Based on the volume of wastewater to be <br />generated and the depth to groundwater (25-30 feet bsg), the potential vertical migration <br />would not likely degrade the local groundwater. A total of 12.33 ppm of additional nitrogen <br />is estimated to be added to the site over the long term through wastewater recharge from <br />the proposed septic system. The nitrogen loading value is above the desired value of <br />10 ppm. <br />10.0. TOTAL NITRATE IMPACT FROM PROPOSED PROJECT <br />Based on the method and assumptions described, proposed NO3_N mass of wastewater <br />