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�.. ..i <br /> August 26,2002 <br /> ` Job Number.LG02-286 <br /> Page 9 <br /> 1500 sf may be placed on the site at some time in the future. Three(3)people were estimated to <br /> occupy the second unit dwelling should it ever be built. The following table tabulates the <br /> anticipated daily usage for the property. <br /> Table 7. <br /> Total Estimated Daily Usage of Septic System. <br /> Category Effluent usage for People per Effluent quantity per category <br /> each category day <br /> Employees(M-Sun) 15 gals 2 2 people* 15 gal/person-day =30 gal/day <br /> Customers 10 gals 100 100 people• 10 gal/person-day'4/7= <br /> (Ih,Fri,SatSun) - 571gal/day <br /> Existing home 75 gals 4 4 people s 100 gal/person-day=400 gal/day <br /> Second Unit i5 gals 3 3 people' 100 gal/person-day=300 gal/day <br /> Dwelling <br /> Average Daily Flow: 1,301 gals/day <br /> Denitrification is an important process in septic systems that normally occurs in the leach <br /> line whereby certain bacteria utilize the oxygen in the nitrate(1103) and release nitrogen gas (NZ) <br /> to the atmosphere. Denitrification is expressed as a percentage, and the normally accepted range <br /> is 10 percent to 35 percent. Soils with higher clay content,moist soil conditions, high pH, and <br /> organic material denitrify about 35 percent and soils with very high sand content and fast <br /> percolation rates are estimated to denitrify at a lower rate, about 10 percent to 15 percent. Due to <br /> the sandy soils, the denitrification factor is estimated to be about 10 percent. <br /> An estimate of the quantity and quality of rainfall is also required for the analysis; <br /> therefore, the following information was used in the calculation. The deep percolation of rain <br /> was estimated to be 6.84 inches and the calculation is shown on Plate 8. The nitrate <br /> concentration of rain fall was estimated to be 0.17 mg/L-N.' <br /> Nitrates from Agriculture <br /> Leaching losses of nitrate fertilizer occur when soils have more incoming water(rain or <br /> irrigation) than the soil can hold. As water moves through the soil, the nitrate(NO3)that is in <br /> soil solution moves along with the water. Ammonium (NH4*) forms of N have a positive charge <br /> and are held by the negative sites on the clay in the soil; therefore,NFW forms of N leach very <br /> ♦r <br /> V •.j�4 <br />