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February 25, 2002 Job Number:LGOI-397 Page 11 to the atmosphere. Denitrification is expressed as a percentage, and the normally accepted range is 10 percent to 35 percent. Soils with higher clay content, moist soil conditions,high pH, and ` organic material denitrify about 35 percent and soils with very high sand content and fast percolation rates are estimated to denitrify at a lower rate, about 10 percent to15 percent. Due to the common occurrence of dark colored(organic layer) clayey surface soils, the denitrification factor is estimated to be about 25 percent. An estimate of the quantity and quality of effluent is required for the analysis therefore the following information was used in the calculation. The deep percolation of rain was estimated to be 7.86 inches and the calculation is shown on the Plate 8. The nitrate concentration of rain fall was estimated to be 0.17 mg/L-N? The quantity of deep percolating rain can be estimated by first converting 7.86 inches of deep percolating rainfall into units of feet. Then by converting acreage(28.40 acres)in to square ` feet and multiplying by feet of deep percolating rain,the volume is determined and is converted into gallons and liters. Roughly 6,061,067 gallons of water from rain fall percolates into the ` ground on the site based on 7.86 inches of deep percolation of rain falling on 28.40 acres. See calculation below. ` 7.86-in (rain)x 28.40-ac x 1-ft/12-in x 43,560-4/1-ac x 7.48-gal/cf=6,061,067 gal (rain) 6,061,067 gal (rain)x 3.785 Ugal =22,941,139 L(rain) .. The quantity of domestic waste water assigned to each staff employee is 15 gallons per day per person. The average nitrate concentration of the typical residential septic waste is normally considered to be 35 mg/L-N'and was utilized for this analysis. The septic waste water flow for the site increases when the temporary employees are present on site for approximately a 10-week period. Table 7 provides the estimated septic system ` waste water flow for the regular staff and temporary staff during an average year. Peak flows (not shown on Table 7)of the temporary employees could potentially reach 9,000 gallons per day for a 2-week period during cherry processing season normally occurring in June(600 people x 15 ` gpd/person= 9,000 gallons/day). pE[SO 1 O `'V �StO�