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a <br /> February 28, 2007 <br /> NOA Project Number: E07023A <br /> t t 2.2 Potential Ground Water Contamination Issues <br /> f A discussion of issues related to potential ground water contamination is included in Section 4.2 of <br /> X the SSS. <br /> 2.3 Current and Future On-Site Ground Water Uses <br /> l <br /> There are currently two wells on the site, as noted in Section 4.3 of the SSS. Ground water will be <br /> used on the site in the future. <br /> t` 3.0 SOURCES AND IMPACT OF NITRATE TO GROUND WATER <br /> � i <br /> 3.1 Current Off-Site Sources of Nitrate <br /> �I Septic systems, agriculture, and dairies in the area may be the most significant sources of nitrate in <br /> ground water. Septic tank use in the vicinity is discussed in Section 3.4 of the SSS. <br /> 3.2 Contribution of Rainfall <br /> An estimate of the quantity and quality of rainfall was required for the nitrate loading analysis. The <br /> estimate of deep percolation of rain is based on the average monthly precipitation of rain fall and <br /> { evapotranspiration for South Stockton, California. The estimate first determines whether the <br /> average monthly precipitation exceeds average monthly potential evapotranspiration. If so, then the <br /> difference is potential deep percolation. This method does not consider runoff. See Plate 9 for the <br /> data and calculation. <br /> e <br /> Average potential evapotranspiration was obtained from the California Irrigation Management <br /> Information System (CIMIS). Stockton is located within evapotranspiration zone number 12. <br /> ' Average rainfall was obtained from the Western.Regional Climate Center (Station 048558). <br /> Based on this method, the average deep percolation of rain for the South Stockton area is estimated <br /> to be 3.3 inches. The nitrate concentration of rain fall was estimated to be 1 mg/L-N (Hantzsche <br /> and Finnemore, 1992). <br /> 3.3 Current On-Site Sources of Nitrate <br /> There are no current on-site sources of nitrate except for natural processes. <br /> F1 <br /> 4 <br /> 1 E <br /> i <br /> 4 <br /> r <br />