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�- December 23,2002 Job Number:LG02492 Page 8 L 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 20 gallons per day per person for an office employee .. category. We understand that a maximum of 6 office employees will work on parcel during regular business hours. All the field labor will utilize portable toilets and the waste from the portable toilets is hauled off site. As mentioned previously, three of the six regular employees (for the farm operation)will also work within the winery. No net increase of em to s is re uired to oD o the winery. No new bathroom facilities will be us or e winery. Table 4 presents a summary of the average daily flow rate for septic waste water. Table 4. Total estimated average daily flow of the septic system. Category Effluent usage for each People Effluent quantity per category category Employees: Combined Winery and 20 gals/day/person 6 6 people• 20 gals/day/person; �- Farm(Mon-Fri is 5/7 of a week) 5 days/7 days=85.7 gal/day Average Daily Flow: 85.7 gals/day �0 Denitrification is an important process in septic systems that normally occurs in the leach line whereby certain bacteria utilize the oxygen in the nitrate(NO3) and release nitrogen gas (NO to 6- 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 to 15 percent. Due to the sandy soils, the denitrification factor is estimated to be about 25 percent. An estimate of the quantity and quality of rainfall was required for the analysis. The deep percolation of rain was estimated to be 6.84 inches and the calculation is shown on Plate 8. The ` nitrate concentration of rain fall was estimated to be 1.0 mg/L-N.' 5.2 Nitrates from Agriculture L Leaching losses of nitrate fertilizer occur when soils have more incoming water(rain or irrigation) than the soil can hold. As water moves through the soil, the nitrate(NO3)that is in .- soil solution moves along with the water. Ammonium(NH4') forms of N have a positive charge and are held by the negative sites on the clay in the soil; therefore,NH4'forms of N leach very 4 V � i O �