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March 26,2003 <br /> Job Number:LGO2-031 <br /> Page 7 <br /> r <br /> be impacted. The nitrate sources considered for this project are percolating septic effluent from <br /> proposed facility and deep percolation of rain water containing nitrate. <br /> The method utilized in this analysis is based on a simple mass balance formula discussed in a <br /> published article by Hantzsche and Finnemore'that provides a convenient and simplified method <br /> to estimate long-term ground-water nitrate impacts on an area-wide basis. Hantzsche and <br /> Finnemore found that over a long period of time,water quality in the upper saturated ground- <br /> water zone closely approximates the quality of percolating recharge waters. They have found that <br /> ` their approach is a good planning tool and provides useful information to planners and local <br /> officials but with some real limitations. In Hantzsche and Fennemore's article,published in <br /> ` Ground Water, they mention that"...the equation ignores dispersion, lateral flow, and mixing <br /> with ground water flow from up-gradient areas. These processes would generally contribute to <br /> additional reduction of nitrate-nitrogen concentrations in ground water to the extent that the <br /> nitrate-nitrogen concentration of ground-water flow from up-gradient areas is lower." <br /> The Hantzsche and Fennemore equation provides"...a conservative (worst case) first <br /> approximation of ground-water nitrate-nitrogen concentration resulting from the combined effect <br /> of on-site sewage disposal systems and precipitation. This (the equation and approach) is for <br /> estimation of long-term effect(i.e., over years)on ground-water quality, and is not intended for <br /> prediction of seasonal changes." <br /> The Hantzsche and Fennemong equation takes into account development area, soil denitrification <br /> factor,rainfall volume,rainfall nitrate concentration,the waste effluent quantity, and waste <br /> effluent nitrate concentration. The formula, assumptions and calculations used for the analysis <br /> are shown on Plates 8 and 9. The units of nitrate used in the mass balance equation are nitrate-N <br /> ` whose maximum drinking water contaminate level is 10 mg/L. <br /> Hantzshe N.N.,Finnemore,E.J. 1991,Predicating Ground-Water Nitrate-Nitrogen Impacts. Ground <br /> Water,Vol. 30,No.4. <br /> pf 430 <br /> l <br /> i <br /> a � <br />