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L <br /> LApril 14, 2006 <br /> NOA Project Number: E06038A <br /> Lbelieve that their method is a good planning tool and provides useful information to planners and <br /> local officials but with some real limitations. In their article published in Ground Water, Hantzsche <br /> and Finnemore mention that"...the equation ignores dispersion,lateral flow,and mixing with <br /> 6. 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 /> 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 /> disposal systems and precipitation. This (the equation and approach) is for estimation of long-term <br /> 6" effect (i.e., over years) on ground-water quality, and is not intended for prediction of seasonal <br /> changes" (Hantzsche and Finnemore, 1992). <br /> L 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 2 and 3. The units <br /> of nitrate used in the mass balance equation are nitrate-N, the maximum drinking water contaminant <br /> level of which is 10 mg/L. <br /> L <br /> 1.0 CHEMICAL AND PHYSICAL PROPERTIES OF SOIL <br /> X1.1 Chemical and Physical Soil Properties <br /> For a discussion of on-site soil properties,refer to Section VI of the original study. <br /> /,/1.2 Mass Transport Soil Properties <br /> 60 Soils on the Site wets £ou-nd to be somewhat sandy) lyrino thr Qtji j1731�tud�`Thcse��i1s a ill allow <br /> moderate to rapid infiltration of water tb1o3Agb the surf&ce sails IfAlaAaudy-soils exist Lathe depth <br /> I <br /> of the.around water table,it is possible that surface contaminants may be transported fain rapidly. <br /> anidly. <br /> 6. <br /> 2.0 GROUND WATER ANALYSIS <br /> V <br /> k/2.1 Regional Ground Water <br /> r <br /> A discussion of regional ground water,including depth to ground water and directional ground <br /> water gradient,is included in Section V of the original study. Ground water lies apnroxiuu=lla 100 <br /> feet below ground surface. For fall 1998,ground water appears to flow to the southeast at a <br /> b. gradient of approximately 7.7 feet per mile in the vicinity of the Site; for spring 1999, the gradient is <br /> approximately 11.1 feet per mile to the southeast. <br /> r <br /> 2 <br />