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Fi <br /> March 28, 2007 <br /> NOA Project Number: E06122A <br /> F1 2.2 Potential Ground Water Contamination Issues <br /> A discussion of issues related to potential ground water contamination is included in Section 4.2 of <br /> F! the SSS. / <br /> 2.3 Current and Future On-Site Ground Water Uses <br /> The use of ground water is not planned for the proposed development. There are no wells on site. _3 <br /> � p p p p rz- <br /> Aux-AL 45:�76:5� 6--" <br /> t 3.0 SOURCES AND IMPACT OF NITRATE TO GROUND WATER <br /> Fj 3.1 Current Off-Site Sources of Nitrate <br /> Septic systems, agriculture, and dairies in the area may be the most significant sources of nitrate in <br /> the county. Septic tank use in the vicinity discussed in Section 3.4 was found to be moderate. No �� <br /> water sample could be taken because no well exists on the site. <br /> Fli <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 Northern Stockton, California. The estimate first determines whether the <br /> F1 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 /> F{ Average potential evapotranspiration was obtained from the California Irrigation Management <br /> Information System (CIMIS). Stockton is located within evapotranspiration zone number 12. The <br /> average rain fall for the North Stockton area was obtained from the Western Regional Climate <br /> F. <br /> Center (www.wrcc.dri.edu), and was found to be 15.98 inches per month for the years 1965 through <br /> 1977. <br /> Based on this method, the average deep percolation of rain for the North Stockton area is estimated <br /> k to be 4.67 inches. The nitrate concentration of rain fall was estimated to be 1 mg/L-N (HantzscheF1 <br /> and Finnemore, 1992)- <br /> 3.3 Current On-Site Sources of Nitrate <br /> FThere are no current on-site sources of nitrate on the property. No additional sources of nitrates <br /> besides groundwater and rainfall are recognized.7-2—);9y <br /> ri <br /> 4 <br />