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August 26,2002 r, Job Number:LG02-286 Page 8 .. method to estimate long-term ground-water nitrate impacts on an area-wide basis. Hantzsche and Finnemore found that over a long period of time,water quality in the upper saturated ground- water zone closely approximates the quality of percolating recharge waters. They have found that their approach is a good planning tool and provides useful information to planners and local officials but with some real limitations. In Hantzsche and Fennemore's article,published in Ground Water,they 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 equation'provides"...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 Hantzsche and Fennemore'equation takes into account development area, soil denitrification 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 8 and 9. The units of nitrate used in the mass balance equation are nitrate-N whose maximum drinking water contaminate level is 10 mg/l. Nitrates from Septic Systems and Rain Fall The average nitrate concentration of the typical septic waste is normally considered to be 45 mg/L-N s (Not to be confused with the maximum contaminate level for drinking water of 45 mg/L-NO3). The average daily flow of influent into the septic systems on the site was determined by assigning a flow rate of fifteen(15) gallons per day per employee and ten(10)per day per customer was used for the winery. Two (2) employees will work on site each day of the ` week. The tasting room is anticipating about 100 customers oer day, and will be open four(4) days per week. One three(3)bedroom home is located on the property. It was estimated that four(4) people will occupy the residence generating approximately seventy-five(75) gallons per day per person. In addition to the primary residence, a legal two (2)bedroom second unit dwelling up to s Otis,RJ.,Boyle,W.C., 1980,Design manual,onsite wastewater treatment and disposal systems:U.S. Environmental Protection Agency,EPA 625/1-80-012. (See page 100,table 6-1). Of ft0 i V