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0 <br /> ki <br /> February 28, 2007 <br /> NOA Project Number: E07023A <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 /> 1 <br /> The Hantzsche and Fennemore approach is "...a conservative. (worst case) first approximation of <br /> -water nitrate-nitrogen concentration resulting from the combined effect of on-site sewage <br /> ground <br /> tdisposal 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 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 /> P, I <br /> 1.0 CHEMICAL AND PHYSICAL PROPERTIES OF SOIL <br /> 1.1 Chemical and Physical Soil Properties <br /> F! For a discussion of on-site soil properties,refer to Section 5 of the SSS. <br /> P <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 to rapid infiltration of water through the surface soils. The longer the effluent remains <br /> near the surface, the more treatment is enhanced due to natural processes within the soil. If the <br /> permeable soils exist to the depth of the ground water table,it is possible that surface contaminates <br /> may be transported fairly rapidly. <br /> M <br /> ` 2.0 GROUNDWATER ANALYSIS <br /> Fill <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. No significant seasonal trends were evident <br /> { from the maps consulted. <br /> F1 <br /> F <br /> 3 <br />