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Hughes Hardwoods L <br /> May 5,2003 <br /> Page 6 <br /> planners and local officials but with some real limitations. In their article published in Ground <br /> Water, Hantzsche and Finnemore mention that"...the equation ignores dispersion, lateral flow, <br /> and mixing with ground water flow from up-gradient areas. These processes would generally <br /> contribute to additional reduction of nitrate-nitrogen concentrations in ground water to the extent <br /> that the nitrate-nitrogen concentration of ground-water flow from up-gradient areas is lower."' <br /> Hantzsche and Finnemore state their approach provides "...a conservative (worst case) first <br /> approximation of ground-water nitrate-nitrogen concentration resulting from the combined effect <br /> of on-site sewage disposal systems and precipitation. This (the equation and approach) is for <br /> estimation of long-term effect (i.e., over years) on ground-water quality, and is not intended for <br /> prediction of seasonal changes."' <br /> The method takes into account development area, soil denitrification factor, rainfall volume, <br /> rainfall nitrate concentration, the waste effluent quantity, and waste effluent nitrate concentration. <br /> The formula, assumptions and calculations used for the analysis are shown on Plates 8 and 9. The <br /> units of nitrate used in the mass balance equation are nitrate-N whose maximum drinking water <br /> contaminate level is 10 mg/L. <br /> 6.1 Quantity of Quality of Domestic Wastewater From the FacilitY' <br /> The average"total nitrogen N"concentration of the domestic residential waste water is normally <br /> considered to be 20-85 mg/L-N with a typical residential concentration of 35 mg/L-N.' The <br /> concentration of total nitrogen of the waste water influent is estimate to be 75 mg/L-N, due to the <br /> lack of shower or kitchen water proposed for the facility. <br /> The calculated peak and average daily flow quantities for the facility are as follows: <br /> 4 Crites,R.W.,and Tchobanoglous,G., 1998,Small and decentralized wastewater management systems: <br /> WCB McGraw-Hill,Boston,First Edition,see Table 4-14,page 181. <br /> s :PERS 1 <br /> Z '• <br /> p A <br /> off pG\ <br />