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F1 April 29, 2005 - <br /> NOA Project Number: E05040A <br /> F <br /> 3.3 Current and Future On-Site Ground Water Uses <br /> N <br /> #r Jf A description of the existing wells on the Site is included in Section 4.3 of the SSS. Ground water is <br /> currently used for residential and agricultural purposes. Ground water will be developed and used <br /> on the rest of the parcels in the future. <br /> 4.0 SOURCES AND IMPACT OF NITRATE TO GROUND WATER <br /> 4.1 Current Off-Site-Sources of Nitrate <br /> Septic systems, agriculture, and dairies in the area may be the most significant sources of nitrate. <br /> ' Septic tank use in the vicinity is discussed in Section 3.4 was found to be moderate. The ground <br /> water sample, discussed in Sections 4.3 through 4.6 of the SSS,was found to have a nitrate <br /> concentration of 13.7 mg/L-NO3. This concentration indicates that the ground water aquifer is <br /> likely not experiencing nitrate leaching from various sources in the area over the long term. <br /> F1l 4.2 Contribution of Rainfall <br /> i J An estimate of the quantity and quality of rainfall was required for the nitrate loading analysis. The <br /> F, estimate of deep percolation of rain-is based on the average monthly precipitation of rain fall and <br /> evapotranspiration for Manteca, California. The estimate first determines whether the average <br /> 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 /> 4 i data and calculation. <br /> Average potential evapotranspiration and average rainfall data was obtained from the California <br /> Irrigation Management Information System (CINIIS). The data from January 1988 to December <br /> 2004 was used for the calculation: <br /> F1Based on this method, the average deep percolation of rain for the Manteca area is estimated to be <br /> 3.54 inches. The nitrate concentration of rain fall was estimated to be 1 m /L-N_(Hantzsche and _ <br /> F Finnemore, 1992). - ~ <br /> 1 4.3 Current On-Site Sources of Nitrate <br /> Current on-site sources of nitrate include the current septic system for the residence. <br /> 4.4- Future.On-Site Sources of Nitrate <br /> 4.4.1 Quantity,and Quality ofDomestic Wastewater From Proposed Project <br /> F <br /> 3 <br /> F <br />