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July 17,2002 Job Number: LG02-136 Page 10 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. To perform the nitrate loading analysis,all the nitrate sources and liquid quantities need to be identified. The following sections discuss the potential concentration of nitrate and quantifies from rain fall, septic systems, and winery waste water. Nitrates from Rain Water An estimate of the quantity and quality of effluent is required for the analysis; therefore, the following information was used in the calculation. To determine the annual deep percolation of rain for the site,the average monthly evapotranspiration(ET)was subtracted from the average monthly rain fall for the Lodi, CIMS weather station. The potential annual deep percolation of rain was estimated by summing up the months where perception exceeds ET. This was estimated to be 6.8 inches. The calculation is shown on Plate 8. The nitrate concentration of rain fall was estimated to be 0.17 mg/L-N based on a range of values used by Hantzsche and Fennemore.7 ., Nitrates from Septic System The average nitrate concentration of the typical septic waste is normally considered to be .. 45 mg/L-N' (this value is often confused with the MCL for drinking water of 45 mg/L-NO3). To estimate the average daily quantity into the septic system, fifteen gallons (15 gal)per day per employee and ten gallons (10 gal)per day per customer was the estimated use for the proposed winery facility. Don Litchfield provided our office with predicted human occupancy for an average year. The following table tabulates the anticipated uses for the property. s Otis,R.J.,Boyle,W.C., 1980,Design manual,onsite wastewater treatment and disposal systems:U.S. r, Environmental Protection Agency,EPA 625/1-80-012. (See page 100,table 6-1). r p.S�4