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June 27, 2005 <br /> NOA Project Number: E05087A <br /> Fand Finnemore mention that "...the equation ignores dispersion, lateral flow, and mixing with <br /> ground water flow from up-gradient areas. These processes would generally contribute to additional <br /> reduction of nitrate-nitrogen concentrations in ground water to the extent that the nitrate-nitrogen <br /> Fi concentration of ground-water flow from up-gradient areas is lower." <br /> The Hantzsche and Fennemore approach is "...a conservative (worst case) first approximation of <br /> f] ground-water nitrate-nitrogen concentration resulting from the combined effect of on-site sewage <br /> disposal systems and precipitation. This (the equation and approach) is for estimation of long-term <br /> effect (i.e., over years) on ground-water quality, and is not intended for prediction of seasonal <br /> changes" (Hantzsche and Finnemore,.1992). <br />? The method takes into account the development area, soil denitrification factor, rainfall volume, <br /> rainfall nitrate concentration,waste effluent quantity, and waste effluent nitrate concentration. The <br /> formula, assumptions and calculations used for the analysis are shown ori Plates 9 through 11. The <br /> units of nitrate used in'the mass balance equation are nitrate-N;whose_ maximum drinking water <br /> RIJ contaminant level is 10 mg/E. <br /> 2.0 CHEMICAL AND PHYSICAL PROPERTIES OF SOIL <br /> I 2.1 Chemical and Physical Soil Properties <br /> F; <br /> For a discussion of on-site soil properties,refer to Section 5.0 of the SSS. <br />' 2.2 Mass Transport Soil Properties <br /> Layered sediments or soils with higher amounts of-silt and clay will-typically_.provide an added <br /> degree of protection between percolating effluent at the surface and shallow ground water aquifers. <br /> # J The sandy soils of the site may present a risk of mass transport of nitrate-or other constituents of <br /> concern. Please see section 6.8 of the-Soil Suitability Study for mitigation:recommendations on this <br /> issue. <br /> E <br /> 3.0 GROUND WATER ANALYSIS <br /> 3.1 Regional Ground Water <br /> A discussion of regional.ground water,including depth to ground water and directional ground <br /> water gradient,is included in Section 4.1 of the SSS. No significant seasonal trends were evident <br /> from the maps consulted. <br /> bJ <br /> Il Z - <br />