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C. PREDICTED NITRATE-NITROGEN LOADING <br /> The calculated or estimated nitrate-nitrogen impact to the soil and ultimately to the groundwater <br /> is difficult to determine due to the number of variables involved. These variables include 1.) <br /> wastewater characteristics, 2.) changes in soil stratification underlying the proposed leachfield, <br /> 3.) impact from upgradient nitrate sources,particularly agricultural, 4.) variability in wastewater <br /> flows, nitrogen concentrations and dilution effects, 5.) changes in groundwater directional flow <br /> and elevation, and 6.) denitrification potential in the referenced clay stratum and potential <br /> landscape uptake of nitrogen. <br /> There are various scientific methods to estimate nitrate-nitrogen loading. This report will use the <br /> Hantzsche/Finnemore Formula to predict the average concentration of nitrate-nitrogen in effluent <br /> recharge water. <br /> PREDICTED NITRATE-NITROGEN LOADING FROM A CONVENTIONAL SEPTIC SYSTEM: <br /> HANTZSCHEIFINNEMORE EQUATION <br /> INS,,(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 <br /> inches per yr. Gross developed area includes all of the area to the south of the Ski Shop <br /> bound to the east by the ski lake and to the west by the drainage/wetlands area <br /> Nw= Total nitrogen concentration of wastewater in mg NIL <br /> d = Fraction(%) of nitrate-nitrogen loss due to denitrification in the soil <br /> R = Average recharge rate of rainfall - inches per yr <br /> Nb= Background nitrate-nitrogen concentration of rainfall recharge, exclusive of wastewater <br /> influences (ppm NO3-N) <br /> Values and Assumptions g� <br /> I= 1,050 gals/d x 30 days/mo x 7 mos._=22.0_,500ag is =total WW/yr 29,476 cu ft= 1.97 in/yr. <br /> 4.13 Ac x 43,560 sq ft/Ac = 180,000 sq ft x (1 ft/12 in) <br /> Nw= 128 mg NIL: 20% reduction from septic tank+ 10%removal from biomat= 92 mg N/L <br /> d = Asiume 30% from underlying clay layer <br /> R = 13 in/yr. <br /> Nb= Assumed to be 0.1 ppm NO3-N <br /> 1.97 in/yr(92 m Ng_/L) 1 - 0.30 + 13 in/yr x 0.1 mg/L) <br /> Nr = (1.97 in/yr+ 13 in/yr) <br /> 8 <br /> Malley Ag Research <br />