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March 11, 2005 <br /> NOA Project Number: E040159A <br /> ground water flow from up-gradient areas. These processes would generally contribute-to additional <br /> F1 reduction of nitrate-nitrogen concentrations in ground water to the extent that the nittate-nitrogen <br /> concentration of ground-water flow.from up-gradient areas is lower." <br /> The Hantzsche and Fennemore.approach is "...a­conservative (worst case) first approximation of <br /> 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 /> F1 effect (i.e.,over years) on ground-water quality, and'is not intended for prediction of seasonal <br /> changes" (Hantzsche and Finnemore;.1992). <br /> FjThe 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 9 and 10. 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 /> 1.0 CHEMICAL AND PHYSICAL PROPERTIES OF SOIL <br /> -+ 1.1 Chemical and Physical Soil Properties - <br /> For a discussion of on-site soil properties,-refer-to Section 5 of the SSS._ <br /> F1 <br /> 1.2 'Mass Transport Soil Properties <br /> ' Layered soils of fine grained sediments, such as the soils found on the Site,typically provide an <br /> added degree of protection between percolatineeffluent at the surface and shallow ground water <br /> aquifers. Soils of.this type do not typically present a high tisk of excessive mass transport of nitrate.. <br /> or other constituents of concern. <br /> y 2.0 GROUNDWATER ANALYSIS <br /> ✓:2.1 Regional Ground Water <br /> A discussion of regional ground water,including depth to ground water and directional ground <br /> �f water gradient,is included in Section 4.1 of the SSS.-.No significant seasonal trends were evident <br /> from the maps consulted. <br /> y�2.2 Potential Ground Water Contamm"atiori'Issues <br /> F <br /> A discussion of issues related to potential ground water contamination is included in Section 4.2 of <br /> F11 <br /> the SSS. 3 <br />