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Farmington Murphy Propertyl �,/ Page 4 <br /> Our Project Number: E07213A <br /> December 24, 2007 <br /> 3.4 Future On-Site Sources of Nitrate rf <br /> G ,¢� <br /> 3.4.1 Quantity and Quality of Domestic Wastewater From Proposed Project <br /> No specific project was selected for the site. We estimate that potential uses for the 4-af re <br /> parcel could be a service station with food service or deli. Another possibility use could be for a <br /> fruit stand with a deli. In either case, customer use rate could range between 0.5 to 2 gallons <br /> per day per customer. The use rate for employees could range between 12 to 14 gallons per <br /> day per employee. Since no specific project is selected at this time, the maximum flow rate and <br /> water concentration will be determined by the nitrate loading study. <br /> The average total nitrogen concentration of domestic waste water is normally considered to be <br /> 20-85 mg/L-N with 35 to 45 mg/L-N being typical (Crites and Tchobanoglous, 1998). It is <br /> estimated that commercial use will have higher concentrations of total nitrogen when compared <br /> to residential use. It is estimated that for a service station with food service or deli or fruit <br /> stand/deli, the average concentration for total nitrogen in waste water for the project is <br /> approximately 85 mg/L-N over the long term. <br /> 3.4.2 Denitrification Estimate <br /> Denitrification is an important process which occurs within the leach field whereby certain <br /> bacteria utilize the oxygen in the nitrate (NO3) and release nitrogen gas (N2) to the atmosphere. <br /> Denitrification is expressed as a percentage, and the normally accepted range is 10 percent to <br /> 35 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 are <br /> estimated to denitrify at a lower rate, about 10 percent to 15 percent. <br /> A denitrification factor of 35 percent was selected for the Site because of the fine grained <br /> nature of the soils. <br /> 3.5 Nitrate Loading Scenario <br /> A nitrate loading scenario was performed to determine the impact from the proposed project. <br /> The scenario utilizes the variables discussed previously which represent the estimated <br /> conditions and uses associated with this project. The following table presents a summary of the <br /> nitrate loading calculation for the site (also, see Plate 2). <br /> ,.,44 <br /> 902 Industrial Way•Lodi,CA 95240.209.367.3701 •Fax 209.369.4228 02007 Neil O.Anderson&Associates,Inc <br />