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../ June 14,2005 NOA Project Number: E05066A Table 1. j Typical Quantity of Effluent for Property. Category Total People per Average Quantity per Average Daily Flow Day Person Per Parcel Residential P/ 7 70 residents*70 gpd/resident 70 gal/day/resident =490 gpd `- Business 2 workers* 13 gpd/worker (Office Worker) 13 gal/day/worker =26 gpd Business 5 gal/day/worker ✓ 6 workers*5 gpd/worker (Truck Driver) =30 gpd Business✓` (Maintenance 4 13 gal/day/worker 4 worker* 13 gpd/worker Employee) =52 gpd Business`/ 2 customers*5 gpd/customer _ Customer 2 5 gal/day/worker = 10 gpd Note —gpd is gallons per day. For the site, the total daily waste water quantitQ* 608 gallons per day. d� 0 " e average total nitrogen concentration of domestic waste water is normally considered to be 7 ` -85 mg/ -N (Crites and Tchobanoglous, 1998). For the purposes of the nitrate loading estimate, the ong-term average concentration for total nitrogen in waste water is estimated to be 45 mg/L-N. 4.4.2 Denitrification Estimate Denitrification is an important process which occurs within the leach field whereby certain bacteria utilize the oxygen in the nitrate (NO3) and release nitrogen gas (N, 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 by about 35 percent, and soils with high sand content and fast percolation rates are estimated to denitrify at a lower rate, about 10 percent to 15 percent. A denitrification factor of 15 percent was selected for the Site. 6- v 4.5 Nitrate Loading Scenario A nitrate loading scenario was performed to determine the impact from the proposed project. The scenario utilizes the variables discussed previously which represent the estimated conditions and uses associated with this project. The following table presents a summary of the nitrate loading calculation for the site. 5