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L <br /> Mr.Steven Malcoun <br /> December 9,2003 <br /> L, Page 12 <br /> Average potential evapotranspiration was obtained from the California Irrigation Management <br /> L, Information System (CIMIS). Lodi 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 /> Based on this estimate, the average deep percolation of rain for the Lodi area is estimated to be <br /> 6.84 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 /> him <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 35 <br /> percent. Soils with higher clay content, moist soil conditions,high pH, and organic material <br /> Ldenitrify 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 tol5 percent. <br /> L A denitrification factor of 35 percent was used for the site which accounts for the dark colored <br /> soil layers reflecting organic carbon, the slow percolation rate of the shallow cemented soil zone. <br /> 6. 7.4 Agricultural Contribution <br /> A walnut orchard exists on the subject property. The contribution of fertilizers has not been <br /> taken into account for use in the Hantzsche and Fennemore equation described later. <br /> Our office believes that due to the presence of the low permeability Morada black clay,whose <br /> top layer is located about 4.5 feet below the ground surface, any migration of fertilizers through <br /> the clay layers will be minimal. Ground water depth was reported to be about 83 to 92 feet in <br /> j Fall 1998 and Spring 1999. Most likely, any fertilizers applied to the ground will stay within the <br /> L upper 5 feet of soil. <br /> 7.5 Nitrate Loading Scenarios <br /> Two nitrate loading scenario was performed to determine the impact from the proposed facility. <br /> Each scenario represents a different parcel size with identical development uses. The following <br /> ` table presents a summary of the nitrate loading results and variables used. <br /> L. <br /> ' VERi�y <br /> C.S� <br />