Laserfiche WebLink
10 September 2020 AdvancedGeo <br /> Project No. 20-6095 An Employ"-OwntdCompany <br /> Page 14 of 15 <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 = I x Nw (1-d)+ R x Nb _ (I+R) <br /> Assumptions: <br /> = 146,000 gallons = 19,518 cubic feet wastewater _ [(0.460 acres x 43,560 feet2) _ 12 <br /> inches] = 19,518 _ 1,670 = 11.69 inches/year <br /> NW = 34.425 mg/L-N <br /> d = 25 percent denitrification <br /> R = 3.69 inches/year <br /> Nb = 1.0 milligram per liter <br /> Nr= [11.69 inches/year x 34.425 mg/L-N (1-0.25)] + (3.69 inches/year x 1.0 milligram per <br /> liter) _ (11.69 inches/year + 3.69 inches/year) <br /> Nr = 305.51 _ 15.38 = 26.40 <br /> Nr = 19.86 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 (20-30 feet bsg), the potential vertical migration <br /> would not likely degrade the local groundwater. A total of 19.86 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 /> 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 /> 19.86 ppm of additional nitrogen is estimated to be added to the site over the long term <br /> through wastewater recharge from the proposed septic system. <br />