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February 25, 2002 Job Number:LG01-397 Page 10 ` can be impacted. The nitrate sources considered for this project are percolating septic effluent from septic systems,the cherry processing waste water and deep percolation of rain water. The ` total nitrate concentration of these combined sources was estimated. The method utilized in this analysis was based on a simple mass balance approach ` 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 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 approach?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 I approach takes into account development area, soil denitrification factor,rainfall volume,rainfall nitrate concentration, the waste effluent quantity, and waste effluent nitrate concentration. In this report,the Hantzsche and Fennemore method was modified to include process waste water generated from Chinchiolo Fruit Company ` and Sierra Hills packing facility. The units of nitrate used in the mass balance are nitrate-N whose maximum drinking water contaminate level is 10 mg/L. Nitrogen from the Septic System and Rain Water _ Denitrification is an important process in septic systems that normally occurs in the leach line whereby certain bacteria utilize the oxygen in the nitrate(NO,) and release nitrogen gas(NO 7 Hantzshe N.N.,Finnemore,E.I. 1991,Predicating Ground-Water Nitrate-Nitrogen Impacts. Ground Water,Vol.30,No.4. ravvro 1 rl Z O QTS Off`• V