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January 16,2.004 <br /> Job Number:LG03-304 <br /> Page 12 <br /> 7:1 Quantity of Quality of°Wastewater <br /> The average total-nitrogen concentration of the domestic waste water is normally considered to. <br /> be 20-85 mg/L-N (Crites and Tchobanoglous; 1998). -Waste water constituent concentration iJ _ <br /> data for restaurants or lounges was not available from Crites and Tchobanoglous, (1998),or the <br /> EPA (1980): <br /> When compared to available residential coricentrations, we believe the waste water of the <br /> w restaurant/lounge should be.similar'due to kitchen wash water. We estimate the long-term <br /> average concentration for total-nitrogen in waste water will most likely be about 35 mg/L-N. e7 <br /> , <br /> 7.2 Quantity and Quality'of Deep Percolating Rain Water-. <br /> An estimate'of the quantity and quality of rainfall was required for the analysis. The'estiniate of <br /> deep percolation of rain is based on the average monthly precipitation of rain fall and <br /> . evapotranspiration for Tracy, California: The calculation first looks at whether the average M, <br /> monthly precipitation'exceeds average monthly potential ET. If.so, then the difference is <br /> potential.deep percolation. This method-does-not consider runoff.' See Plate 4 for.the data and <br /> calculation. <br /> Average potential evapotranspiration was obtained frorn the California Irrigation Management <br /> Information System (CIMIS). Tracy is located within evapotranspiration zone number 12. The <br /> average rain fall for the Lodi area'was obtained from the USDA(1992) Soil Survey for San <br /> Joaquin County. . <br /> 13 approach,Based on this a roach, p the` g avera e dee percolation of rain-for.the Tracy area is estimated to be <br /> 1.07 inches. The nitrate concentration of rain fall was estimated to•be 1 mg/L-N whose maximum <br /> contaminate limit for drinking water is,10 mg/L-N (Hantzsche and Finnemore,.1992). <br /> 7.3 Denitrification Estimate <br /> Denitrifcatian 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 35 <br /> k 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 are estimated to denitrify at a <br /> dower rate, about 10 percent t615:percent.' <br />