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«Project_Name» Page 10 Our Project Number: LGS080005 February 28, 2008 The following table presents the septic waste water uses associated with the Site. The rates presented from the references provide general guidance but do not always reflect a match in usage. Careful examination, professional judgment, and experience are necessary to select a reasonable flow rate estimate. The flow rates selected for the uses associated with this project are presented next. Table 6. Typical Quantity of Effluent. Category Total People Average Quantity per Average Daily Flow per Parcel per Day Person Employees 1 13 gal/day/employee a employee * 13 god) * 5/7 = 9.29 Note: god is gallons per day. * 517ths is used to account for a five day work week. For the subject property, the total daily waste water quantity is 9.29 gallons per day. A five- sevenths conversion was used to account for a five day work week. Five-sevenths of 13 gallons per day is 9.29 gallons per day average. The average total nitrogen concentration of domestic waste water is normally considered to be 20-85 mg/L-N with 35 to 45 mg/L-N being typical (Crites and Tchobanoglous, 1998). It is estimated that commercial use will have higher concentrations of total nitrogen when compared to residential use. It is estimated that the average concentration for total nitrogen in waste water for the project is approximately 85 mg/L-N over the long term. 2.3.4.2 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 (NZ) 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 35 percent was selected for the Site because of the fine grained _ nature of the soils. 2.3.5 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, as presented in Plate 8. '004r 902 Industrial Way•Lodi,CA 95240•209.367.3701 •Fax 209.369.4228 02008 Neil O.Anderson&Associates,Inc