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(-Where: <br />Nr = Resultant average concentration of nitrate-nitrogen in recharge water - (ppm NO3-N) <br />I = Volume rate of wastewater entering the soil averaged over the gross developed area in ac-ft <br />Nw = Total nitrogen concentration of wastewater in mg NIL <br />d = Fraction (%) of nitrate-nitrogen combined loss in the high clay content soil due to: <br />1.) Prevention of nitrification and 2.) The denitrification of nitrate molecules that may form. <br />R = Estimated Annual Rainfall Recharge in ac-ft <br />Nb = Background nitrate-nitrogen concentration of rainfall recharge, exclusive of wastewater influences <br />(ppm NO3-N). <br />Values and Assumptions: <br />1= 971,712 gals/yr = 2.98 ac-ft <br />Nw = 90 mg N/L <br />d = Assume 25% due to the high percentage of clay soil (29%) throughout the soil profile that not only <br />mitigates nitrification, but also promotes denitrification of nitrate molecules that may form. <br />R = 27.51 ac-ft <br />N b = Assumed to be 0.1 ppm NO3-N <br />2.98 ac-ft (90 mg N/L) (1 -0.25) + (27.51 ac-ft x 0.1 mg/L) <br />Nr = (2.98 ac-ft + 27.51 ac-ft) <br />Nr = 6.7 ppm as nitrate-nitrogen (NO3-N) <br />Original Chesney Consulting Report Calculations using San Joaquin County Isohyetal Map Data <br />(1 - d) + R Nb <br />Nr = (I + R) <br />Where: <br />Nr = Resultant average concentration of nitrate-nitrogen in recharge water - (ppm NO3-N) <br />I = Volume rate of wastewater entering the soil averaged over the gross developed area in inches per yr <br />Nw = Total nitrogen concentration of wastewater in mg NIL <br />d = Fraction (%) of nitrate-nitrogen combined loss in the high clay content soil due to: <br />1.) Prevention of nitrification and 2.) The denitrification of nitrate molecules that may form. <br />R = Average recharge rate of rainfall - inches per yr <br />Nb = Background nitrate-nitrogen concentration of rainfall recharge, exclusive of wastewater influences <br />(ppm NO3-N). <br />Page 2 of 3 <br />Chesney Consulting