Laserfiche WebLink
CALCULATED NITRATE-NITROGEN LOADING: <br />HANTZSCHE/FINNEMORE EQUATION <br />IN,(1 - d) + R N b <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 loss first in the septic tank and then due to denitrification in the <br />soil environment. <br />R = Average recharge rate of rainfall - inches per yr NLS§ 3.2 <br />N1, = Background nitrate-nitrogen concentration of rainfall recharge, exclusive of wastewater influences <br />(ppm NO3-N). <br />Values and Assumptions: <br />I = 600 gbd x 365 d/v = 219,000 gals/v = 29,278 cu ft = 3.05 in/yr <br />2.65 Ac x 43,560 sq ft/Ac x (1 ft/12 in) <br />Nw = 35 mg N/L <br />d = Assume 20% N reduction in both septic tanks (Ref. 8) and 70% denitrification due to the construction method <br />of the mound systems and to the high clay content soil that retards nitrification and readily denitrifies nitrified <br />ammonium (Ref 3 and 5). <br />R = 2.21 in/yr. <br />Nb = Assumed to be 0.1 ppm NO3-N <br />3.05 in/yr (35 mg N/L x (1- 0.20)) = 85.4 x (1 -0.70) = 25.62 +(2.21 in/yr x 0.1 mg/L) = 4.9 ppm <br />Nr = (3.05 in/yr + 2.21 in/yr) <br />Nr = 4.9 ppm as nitrate-nitrogen (NO3-N) or 21.9 ppm as nitrate (NO3) <br />7 <br />Chesney Consulting