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CALCULATED NITRATE-NITROGEN LOADING NLS§3.3,3.4—,3.9,3.6. The calculated nitrate-nitrogen impact to the soil and potentially to the groundwater is difficult to determine due to the large number of variables involved and variables unknown at this time. These include: 1.) Impact from upgradient agricultural sources, 2.) Variability in wastewater flows, nitrogen concentrations and dilution effects from stormwater _- recharge, 3.) Changes in groundwater directional flow and elevation, 4.) Denitrification potential within the clay soil environment and within the confined and/or unconfined aquifers. The Hantzsche/Finnemore Formula is used in this report to predict the average resultant concentration of nitrate-nitrogen in effluent recharge water. As calculated below,the property has been assessed on a total areal loading basis correlated with the total projected yearly wastewater flow volumes calculated above. These two factors primarily estimate the average resultant concentration of nitrate-nitrogen in the recharge water. This concentration shall not exceed 10 ppm nitrate-nitrogen(45 ppm as nitrate). If the concentration exceeds this standard,mitigation measures must be implemented. Calculated nitrate-nitrogen loading from the entire subject property: IN(1 -_d) + RNb Nr= (I + R) Where: Nr = Resultant average concentration of nitrate-nitrogen in recharge water-(ppm NO3-N) I = Volume rate of wastewater entering the soil averaged over the gross developed area in inches per yr Nw = Total nitrogen concentration of wastew5ter in mg N/L d = Fraction(%)of nitrate-nitrogen loss due to denitrification in the soil R = Average recharge rate of rainfall- inches per yr NLS§3.2 Nb = Background nitrate-nitrogen concentration of rainfall recharge,exclusive of wastewater influences (ppm NO3-N)- Values and Assumptions: I=700 x 365 d/vr=255.500 aals=total W W/vr=34.158 cu ft = 10.34 in/yr 0.91 Ac x 43,560 sq ft/Ac x (1 8/12 in) Nw=62 mg N/L d = Assume 30%due to very high percentage of fine-grained clay soil. R = 9 in/yr. Nb= Assumed to be 0.1 ppm NO3 N 10.34 in/yr(62 me N/L) (1 -0.30)+(9 in/yr x 0.1 mg/L) Nr = (10.34 in/yr+9 in/yr) = 23 3 ppm as n trate-nitrogen (NO3-N) or 104.6 ppm as nitrate(NO3) Page 5 of 12