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13 August 2021 Project No. 21-6530 Page 12 of 14 AdvancedGeo Ari Err poe Owned Company d = Fraction of nitrogen concentration removed from the wastewater due to denitrification within the soil (30 percent for clay and loamy soils). R = Estimated Deep percolation / average rainfall recharge rate per year: 3.20 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 AND PROPOSED HOME CALCULATIONS: Nr=IxNw(1-d)+RxNb=(I+R) Assumptions: I = 73,000 gallons = 9,759 cubic feet wastewater - [(0.172 acres x 43,560 feet2) _ 12 inches] = 9,759 - 624.3 = 15.63 inches/year NW = 34.425 mg/L-N d = 30 percent denitrification R = 3.20 inches/year Nb = 1.0 milligram per liter Nr = [15.63 inches/year x 34.425 mg/L-N (1-0.30)] + (3.20 inches/year x 1.0 milligram per liter) - (15.63 inches/year + 3.20 inches/year) Nr=379.8= 18.83=20.17 Nr = 20.17 ppm nitrogen (NO3_N) 9.7. IMPACT OF NITROGEN LOADING FROM SITE PROJECT TO DOWNGRADIENT WATER SOURCES The recharging of groundwater is the most likely potential feature that could impact future nitrogen loading. Since the subject property is flat, AGI does not anticipate percolating effluent will affect any nearby water sources. Based on the volume of wastewater to be generated and the depth to groundwater (70 feet bsg), the potential vertical migration would not likely degrade the local groundwater. A total of 20.17 ppm of additional nitrogen is estimated to be added to the site over the long term through wastewater recharge from the proposed septic system. The nitrogen loading value is above the desired value of 10 ppm. 10.0. TOTAL NITRATE IMPACT FROM PROPOSED PROJECT Based on the method and assumptions described, proposed NO3_N mass of wastewater and the calculations of the NO3_N loading predicted, the proposed development may