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6. <br /> February 21,2007 <br /> NOA Project Number: E07015A <br /> ground water flow from up-gradient areas. These processes would generally contribute to additional <br /> V <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 /> 6. 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 (Le.,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 /> Lformula, 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 /> Lcontaminant level is 10 mg/L. <br /> L1.0 CHEMICAL AND PHYSICAL PROPERTIES OF SOIL <br /> 1.1 Chemical and Physical Soil Properties <br /> LFor a discussion of on-site soil properties,refer to Section 5 of the SSS. <br /> L2 Mass Transport Soil Properties <br /> V <br /> L" The percolation tests have revealed that the soils are fairly permeable.These soils will allow <br /> L 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 /> 6. <br /> 2.0 GROUND WATER ANALYSIS <br /> 2.1 Regional Ground Water <br /> LA 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 /> Lfrom the maps consulted. <br /> L <br /> L 3 <br /> L <br />