Laserfiche WebLink
Various scientific methods exist to estimate nitrate -nitrogen loading. This Study uses the Hantzsche/ <br />Finnemore equation to predict the average resultant concentration of nitrate -nitrogen in effluent recharge <br />water from the proposed conventional OWTS to serve the three bedroom, two bath modular home. The <br />nitrate -nitrogen concentration in the effluent shall not exceed the Maximum Contaminant Level (MCL) of <br />10 ppm nitrate -nitrogen (45 ppm as nitrate). <br />As indicated below, the calculations demonstrate that the resultant concentration of nitrate -nitrogen will not <br />exceed the MCL. <br />CALCULATED NITRATE -NITROGEN LOADING: <br />HANTZSCHEIFINNEMORE EQUATION <br />Li. LL- d, +RNb <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 N/L <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 />Nb = Background nitrate -nitrogen concentration of rainfall recharge, exclusive of wastewater influences <br />(ppm NO3-N). <br />Values and Assumptions: <br />I = 200 and x 365 d/v = 73,000 gals/y = 9,759 cu ft = 1.78 in/yr <br />1.51 Ac x 43,560 sq ft/Ac x (1 ft/12 in) <br />Nw = 45 mg N/L <br />d = Assume a 60% denitrification due to high clay content soil which has been observed in this soil type. <br />R = 2.21 in/yr. <br />Nb = Assumed to be 0.1 ppm NO3-N <br />1.78 in/yr (45 mg N/L) = 80.2 x 0 - 0.60) = 32.04 + (2.21 in/yr x 0.1 me/L) = 8.1 ppm <br />Nr = (1.78 in/yr + 2.21 in/yr) <br />Nr = 8.1 ppm as nitrate -nitrogen (N0; N) or 36 ppm as nitrate (NO3) <br />70, <br />Chesney Consulting <br />