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4. Pastor Matt Linder May 5,2003 Page 2 _ Division, (PHS-EHD) for the proposed church facility to measure the potential concentration of 1 percolating effluent and rain fail over the-long term. If the proposed project will dispose of septic effluent to a shallow leach field, groisnd.water quality may be impacted to some degree. ' The method utilized for the nitrate loading analysis is'based on a simple mass balance formula, discussed in a published article by Hantzsche and Finnemore,' which provides a convenient.and simplified method to estimate long-term ground-water nitrate impacts on an area-wide basis. ,Hantzsche and Finnemore found that over along period of time, water quality in the upper saturated ground-water zone closely approximates the quality of percolating recharge waters.They believe that their method is a good planning tool and provides useful information to planners'and local officials but with some real limitations, In their article published in Ground Water, Hantzsche and i Finnemore mention that":..the equation ignores dispersion,lateral flow,-and mixing with ground water . flow from up-gradient areas. These processes would generally contribute to additional reduction of nitrate-nitrogen concentrations in ground water to the extent that the nitrate-nitrogen concentration of ground-water flow from up-gradient areas is lower."` The Hantzsche and Fennemore approach"...a conservative(worst case)first approximation of ground-water nitrate-nitrogen concentration-resulting from the combined effect of on-site sewage .disposal systems and precipitation. This(the equation and approach) is for estimation of long-term effect (i.e.,over.years) on ground-water quality, and is'not.intended for prediction of seasonal changes."` . The method takes into account development area, soil denitri fication'factor, rainfall volume, rainfall nitrate concentration,the waste effluent quantity, and waste effluent nitrate concentration. The formula,assumptions and calculations used for the analysis are shown on Plates 1 through 3. The units of. nitrate used in the mass balance equation are nitrate-N whose maximum drinking water contaminate level is 10 mg/L. Quantity of Quality of Domestic.Wastewater From the Church The average total nitrogen concentration of the domestic waste water is normally considered to be 20-85 mg/L-N with a typical concentration of 35 m /L`N. 2 Waste water for churches and schools are .typically higher in total nitrogen because the waste water is not diluted with shower or kitchen water. Mr.Bob Smith,technical expert, Orenco Systems Incorporated(OSI),indicated the average total nitrogen concentration of influent for a church facility would probably b"about 75 m IL N over a Yon a term period. .Therefore'the.estimated concentration of total nitrogen of the waste water is estimate to.be 75 mg/L-N,total nitrogen for the revised nitrate loading study. i 1 Hantzshe N.N.,Finnemore,E.J. 1991,Predicating Ground-Water Nitrate-Nitrogen hnpacts. Ground Water, Vol.30,No.4. z Crites,R.W.,and Tchobanoglous,G.,.1998,Small and decentralized wastewater management systems: WCB McGraw-Hill,Boston,First Edition,see Table,4-14,page 181. ?9Earn ' R