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jr December 14,2005 <br /> NOA Project Number: E05116B <br /> ` (2003), Crites and Tchobanoglous (1998), and EPA (1980). The text from Crites and Tchobanoglous <br /> (1998) (Table 4-2) indicates that the typical residential use rate is 70 gallons per day. The EPA <br /> (1980) Design Manual (Table 4-6) indicates the typical use rate is 45 gallons per day for a resident. <br /> L <br /> ✓The following tables presents the septic waste water uses associated with the Site. The rates <br /> presented from the references provide general guidance but do not always reflect a match in usage. <br /> Careful examination,professional judgement, and experience are necessary to select a reasonable <br /> flow rate estimate. The flow rates selected for the uses associated with this project are presented <br /> next. <br /> Table 1. <br /> Typical Quantity of Effluent <br /> y Category Total People per Average Quantity per Average Daily Flow <br /> Day _ �ersnn_ Pet Parcel <br /> Residential 18 residents* 70 gpd/resident <br /> �. is 1- = 560 eDd <br /> Note —gpd is gallons per day. <br /> �. For lots 1-7, the total daily waste water quantity is 560 gallons per day. <br /> /The average total nitrogen concentration of domestic waste water is normally considered to be <br /> 20-85 mg/L-N with 45 mg/L as typical (Crites and Tchobanoglous, 1998). For the purposes of the <br /> nitrate loadin tate- <br /> estimated <br /> g-term average concentration for total nitrogen in waste water is <br /> estimated to 45 m L- <br /> r <br /> 3 Y 13.4.2 Denieri6caiion Estimate <br /> Denitrification is an important process which occurs within the leach field whereby certain bacteria <br /> utilize the oxygen in the nitrate (NO3) and release nitrogen gas (N� to the atmosphere. <br /> Denitrification is expressed as a percentage, and the normally accepted range is 10 percent to 35 <br /> r percent. Soils with higher clay content,moist soil conditions,high pH, and organic material <br /> denitrify by about 35 percent,and soils with high sand content and fast percolation rates ase <br /> estimated to denitrify at a lower rate,about 10 percent to 15 percent. <br /> r <br /> A typical denitrification factor of 25 percent was selected for the Site due to the presence of fine- <br /> grained soil. <br /> r <br /> r <br /> 'r <br /> 5 <br /> "0*4r <br />