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FCALCULATED NITRATE-NITROGEN LOADING . <br /> 3:3,3.4,3.5,3.6. The calculated nitrate-nitrogen impact to the soil.and ultimately to the <br /> dwater is difficult to determine due to the large number of variables involved and unknown at <br /> me. These include:_1.}Variability in wastewater flows, nitrogen concentrations and dilution <br /> effects that may occur, 2.) Impact from upgradient nitrate sources; 3.)Changes in groundwater <br /> directional flow and elevation, 4.) Denitrification potential within the,soil environment and within <br /> the confined and/or unconfined aquifers, and 5.) Potential landscape uptake of nitrogen. <br /> Various scientific methods exist to estimate nitrate-nitrogen Ioading. This.Study uses the . <br /> Hantzsche/Finnemore 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 <br /> been assessed on a total.areal.loading basis correlated with the total number of people on-site every, <br /> week of the year. These.two factors primarily estimate the average resultant concentration of <br /> nitrate-nitrogen in the recharge water, along with timation of the nitrogER concentration in the <br /> effluent. The effluent concentration.cannot excee10 p in nitrate-nitrogen (4�\ppm as nitrate). <br /> Wastewater researchers place the nitrogen reduction-occurring in septic tanks at 10% to 20%. From <br /> the May 8, 2003 Symposium "Onsite Wastewater Treatment -Nitrogen Removal," Dr. Stuart <br /> Oakley of California State University Chico states that"approximately 20% of the total nitrogen <br /> generated is removed in the septic tank" (Ref. 11). As noted below, this estimate of 20% is used for <br /> nitrogen reduction occurring in.the:septic tank. <br /> PREDICTED NITRATE-NITROGEN LOADING FROM A COMPLETELY BUILT- <br /> OUT PROJECT USING AN E.H.D. APPROVED SEPTIC SYSTEM: <br /> HA NTZSCHEIFINNEMORE EQUATION <br /> Nr = (I + R) <br /> Where: <br /> Nr = Resultant average concentration-of nitrate-nitrogen in recharge water-(ppm NO;-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 tan_k 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 /> 13 . <br /> Chesney Consulting <br />