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B. CALCULATED NITRATE-NITROGEN LOADING <br /> NLS§3.4,3.5,3.6. The calculated nitrate-nitrogen impact to the soil and ultimately to the <br /> groundwater is difficult to determine due to the large number of variables involved and variables <br /> unknown at this time. These include: 1.) Installation methods, structures and sizes of the on-site <br /> wastewater management system, 2.) Impact from upgradient nitrate sources, 3.) Variability in <br /> wastewater flows, nitrogen concentrations and dilution effects from effluent and stormwater <br /> recharge, 4.) Changes in groundwater directional flow and elevation, 5.)Denitrification potential <br /> within the soil environment and within the confined and/or unconfined aquifers and 6.) Potential <br /> landscape uptake of nitrogen. <br /> Various scientific methods exist to estimate nitrate-nitrogen loading. This Study uses the <br /> HantzschelFinnemore Formula to predict the average resultant concentration of nitrate-nitrogen in <br /> effluent recharge water from a conventional septic system. As calculated below,the property has been <br /> assessed on a total areal loading basis correlated with the total projected number of people on-site <br /> every week of the year. These two factors primarily estimate the average resultant concentration of <br /> nitrate-nitrogen in the recharge water. This concentration cannot exceed 10 ppm nitrate-nitrogen(45 <br /> ppm as nitrate). <br /> f <br /> PREDICTED NITRATE-NITROGEN LOADING FROM A COMPLETELY BUILT- <br /> OUT PROJECT USING AN E.H.D. APPROVED SEPTIC SYSTEM: <br /> HANTZSCHEIFINNEMORE EQUATION <br /> it!,,(I - d) + RNb <br /> Nr= (I +R) <br /> Where: <br /> Nr = Resultant average concentration of nitrate-nitrogen in recharge water-(ppm NO;-N) <br /> l = 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 due to denitrification in the soil <br /> R = Average recharge rate of rainfall- inches per yr NLS§3.2 ' <br /> N5 = Background nitrate-nitrogen concentration of rainfall recharge, exclusive of wastewater influences <br /> (ppm NO,-N). <br /> Values and Assumptions: <br /> a <br /> 1= 65,000 gals=total WW/yr=8,690 cu ft = 1.00 in/yr , <br /> 2.41 Ac x 43,560 sq ft/Ac x (1 ft/12 in) i <br /> y <br /> 9 T <br /> Chesney Consulting <br />