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17 January 2020 AdvancedGeo <br /> Project No. 19-4964 An Employee-Owned Company <br /> Page 13 of 14 ,,' <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 HOME AND PROPOSED HOME CALCULATIONS (COMBINED): <br /> Nr = I x Nw (1-d)+ R x Nb - (I+R) <br /> Assumptions: <br /> I = 255,500 gallons = 34,157 cubic feet wastewater_ [(3 acres x 43,560 feet') - 12 inches] <br /> = 3.14 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 = [3.14 inches/year x 34.425 mg/L-N (1-0.25)] + (3.64 inches/year x 1.0 milligram per <br /> liter) _ (3.14 inches/year + 3.64 inches/year) <br /> Nr = 84.71 - 6.78 = 12.49 <br /> Nr = 12.49 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, the potential vertical migration would not likely degrade the local groundwater. <br /> A total of 12.49 ppm of additional nitrogen is estimated to be added to the site over the <br /> long term through waste water recharge from the existing and proposed septic systems. <br /> The nitrogen loading value is slightly above the desired value of 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 /> and the calculations of the NO3_N loading predicted, the proposed development may <br /> negatively impact NO3_N loading rates within the aquifer. The soil at the site appear to <br /> be adequate for nitrate degradation and proper leaching of wastewater. A total of <br /> 12.49 ppm of additional nitrogen is estimated to be added to the site over the long term <br /> through waste water recharge from the existing and proposed septic systems. <br />