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.. 2.3 Current and Future On-Site Ground Water Uses <br /> The use of ground water is planned for the proposed development. There js currently one well on/ <br /> the site.This well will be used for the proposed lumber yard on the site. <br /> 3.0 SOURCES AND IMPACT OF NITRATE TO GROUND WATER <br /> 3.1 Current Off-Site Sources of Nitrate <br /> Septic systems, agriculture,and dairies in the area may be the most significant sources nitrate. <br /> Septic tank use in the vicinity discussed in Section 3.4 of the SSS was found to be low. onsite <br /> r water well was tested for nitrate and DBCP. The results of this analysis are forthcoming. <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 rainfall and <br /> r evapotranspiration for Tracy, California.The estimate first determittes w Eh'-eW average monthly/ <br /> precipitation exceeds average monthly potential evapotranspiration. Ifs en ference is <br /> potential deep percolation. This method does not consider runoff. Se Plate 5 the data and <br /> calculation. <br /> Average potential evapotranspiration was obtained from the California Irrigation Management <br /> Information System (CIMIS). Tracy is located within evapotranspiration zone number 12. The <br /> average rain fall for the West Tracy area was obtained from the Western Regional Climate Center <br /> (www.wrcc.dri.edu), and was found to be 12.18 inches per month for the years 1955 through 2004. <br /> V = <br /> Based on this method, the average deep percolation of rain for the West TYacy area is estimated to <br /> be 2.52 inches. The nitrate concentration of rain fall was estimated to be mg/L-N (I-Iantzsche and <br /> Finnemore, 1992). <br /> 3.3 Current On-Site Sources of Nitrate <br /> Current on-site sources of nitrate include the current septic system associated with the current <br /> residence on site. No additional sources of nitrates besides septic effluent,groundwater and rainfall <br /> are recognized. <br /> 3.4 Future On-Site Sources of Nitrate <br /> 3.4.1 Quantity and Quality ofDomestic Wastewater From Proposed Project <br /> The following discussion is for determining the long-term waste water flow generated from the <br /> proposed residences or commercial usage for the nitrate loading analysis and should not be used for / <br /> septic system design purposes. Typically, use estimates for the sizing of septic systems include a <br /> peak use factor,whereas the numbers discussed here are based on long-term averages. <br /> 4 <br />