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_ November 23, 2004 <br /> NOA Project Number: E040140A <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 /> 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 10 and 11. The <br /> units 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 /> 1.2 Mass Transport Soil Properties <br /> ` The soil profile examined on the Site was found to be a brown silty sand to the depth of <br /> investigation which was three (3) feet. The soil at a depth of 3.0 feet had a permeability of 1.8 <br /> minutes per inch in a percolation test. This rate is considered rapid. Should this layer continue to <br /> the depth of ground water (17 to 18 feet), any contaminants could potentially percolate to ground <br /> water and disperse. <br /> 2.0 GROUND WATER ANALYSIS <br /> 2.1 Regional Ground Water <br /> A discussion of regional ground water,including depth to ground water,is included in Section 4.1 of <br /> the SSS. The ground water depth below the site was found to be 17 to 18 feet for 1998 and 1999. <br /> 2.2 Potential Ground Water Contamination Issues <br /> A discussion of issues related to potential ground water contamination is included in Section 4.3 of <br /> the SSS. <br /> 2 <br />