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15 November 2019 AdvancedGeo <br /> AGE Project No. 19-4912 Environmental <br /> Page 12 of 14 <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 /> 560 gpd (proposed system) x 365 days of proposed operation = 560 x 365 days . 7.48 <br /> gallons per cubic foot = 27,326 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 (25 percent for sandy loam soils). <br /> R = Estimated Deep percolation / average rainfall recharge rate per year: 3.64 inches. <br /> Nb = Background nitrate-nitrogen concentration of rainfall recharge: 1.0 mg/l. The Nb is <br /> an average value determined for San Joaquin County by the EHD. <br /> PROPOSED HOME CALCULATIONS: <br /> Nr = I x Nw (1-d)+ R x Nb - (I+R) <br /> Assumptions: <br /> I = 204,400 gallons = 27,326 cubic feet wastewater = [(1.502 acres x 43,560 feet2) _ 12 <br /> inches] = 5.01 inches/year <br /> NW = 34.425 mg/L-N <br /> d = 25 percent denitrification <br /> R = 3.64 inches/year <br /> Nb = 1.0 milligram per liter <br /> Nr = [5.01 inches/year x 34.425 mg/L-N (1-0.25)] + (3.64 inches/year x 1.0 milligram per <br /> liter) _ (5.01 inches/year + 3.64 inches/year) <br /> Nr = 132.99 _ 8.65 = 14.96 <br /> Nr = 15.37 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, AGE does not anticipate percolating <br /> effluent will affect any nearby water sources. Based on the volume of wastewater to be <br /> generated, the potential vertical migration would not likely degrade the local groundwater. <br />