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F1 February 22, 2006 <br /> NOA Project Number: E06010A <br /> 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 /> 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 /> effect (i.e., over years) on ground-water quality, and is not intended for prediction of seasonal <br /> F1changes" (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 10 and 11. The <br /> units of nitrate used in the mass balance equation are nitrate-N, the maximum drinking water <br /> F1contaminant level of which is 10 mg/L. <br /> 1.0 CHEMICAL AND PHYSICAL PROPERTIES OF SOIL <br /> 1.1 Chemical and Physical Soil Properties <br /> a <br /> 1 For a discussion of on-site soil properties, refer to Section 5 of the SSS. <br /> 1.2 Mass Transport Soil Properties <br /> F <br /> The deep soils on the Site were found to be fairly sandy. These soils will allow moderate to rapid <br /> # infiltration of water through the surface soils. If the sandy soils exist to the depth of the ground <br /> } water table,it is possible that surface contaminants may be transported fairly rapidly. <br /> + /2.1 <br /> 2.0 GROUND WATER ANALYSIS <br /> P <br /> 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. Ground water lies between 160 and 180 feet <br /> P below ground surface. For fall 1998,ground water appears to.flow to the west-southwest at a <br /> gradient of approximately 5 feet per mile in the vicinity of the Site; the gradient is unclear for spring <br /> 1999. <br /> F <br /> ' 2 <br /> F, <br /> ! J <br />