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March 15,2007 <br /> NOA Project Number: E07031A <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) fust 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 /> changes" (Hantzsche and Finnemore, 1992). <br /> The method takes into account the development area, soil denitrification factor, rainfall volume, <br /> r„ 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 /> Ll Chemical and Physical Soil Properties <br /> For a discussion of on-site soil properties,refer to Section 5 of the SSS. <br /> ` 1.2 Mass Transport Soil Properties <br /> The percolation tests have revealed that the soils are fairly permeable.These soils will allow <br /> moderate infiltration of water through the surface soils. The longer the effluent remains near the <br /> surface, the more treatment is enhanced due to natural processes within the soil. <br /> 2.0 GROUND WATER ANALYSIS <br /> ` 2.1 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. Ground water lies between 10 and 20 feet <br /> below ground surface and flows at an indeterminate gradient in the vicinity of the site in 1999. <br /> ` 2.2 Potential Ground Water Contamination Issues <br /> A discussion of issues related to potential ground water contamination is included in Section 4.2 of <br /> ` the SSS. <br /> 2 <br /> r <br />