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i. <br /> July 5,2005 <br /> NOA Project Number: E05027A <br /> L and 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 /> concentration of ground-water flow from up-gradient areas is lower." <br /> V <br /> The Hantzsche and Fennemore approach is "...a conservative (worst case) first approximation of <br /> ground-water nitrate-nitrogen concentration resulting from the combined effect of on-site sewage <br /> L 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 on Plates 1 and 2. The units <br /> of nitrate used in the mass balance equation are nitrate-N,whose maximum drinking water <br /> contaminant level is 10 mg/L. <br /> r <br /> 2.0 CHEMICAL AND PHYSICAL PROPERTIES OF SOIL <br /> 2.1 Chemical and Physical Soil Properties <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 /> The cemented and fine-grained soils of the site should not present an obvious risk of mass transport <br /> of nitrate or other constituents of concern. <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 /> L <br /> h. <br /> 2 <br />