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22 December 2020 AdvancedGeo <br /> Project No. 20-6228 An Employee Owned Company <br /> Page 13 of 15 - Z. <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 (proposed system) x 365 days of proposed operation = 250 x 365 days - 7.48 <br /> gallons per cubic foot = 12,199 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 (30 percent for loamy soils). <br /> R = Estimated Deep percolation / average rainfall recharge rate per year: 3.69 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 = 1xNw (1-d) + RxNb = (I+R) <br /> Assumptions: <br /> I = 91,250 gallons = 12,199 cubic feet wastewater - [(1.5 acres x 43,560 feet') - 12 <br /> inches] = 12,199 - 5,445 = 2.24 inches/year <br /> NW = 34.425 mg/L-N <br /> d = 30 percent denitrification <br /> R = 3.69 inches/year <br /> Nb = 1.0 milligram per liter <br /> Nr = [2.24 inches/year x 34.425 mg/L-N (1-0.30)] + (3.69 inches/year x 1.0 milligram per <br /> liter) _ (2.24 inches/year + 3.69 inches/year) <br /> Nr = 57.67 = 5.93 = 9.72 <br /> Nr = 9.72 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 9.72 ppm of additional nitrogen <br /> is estimated to be added to the site over the long term through wastewater recharge from <br />