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February 15,200G <br /> NOA Project Number: E06006A <br /> 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 /> the SSS'. <br /> 2.3 ..Current and Future On-Site Ground Water Uses <br /> One domestic water well exists on <br /> the property and is associated with the single-family residence.. <br /> One agricultural well is also located on the Site. The EHD is requiring repairs to both wells as a <br /> condition of project approval: In addition, a new well must be constructed to provide potable water <br /> _ to the proposed agricultural store and deli. <br /> 3.0. SOURCES AND IMPACT OF NITRATE TO GROUND WATER <br /> 3.1 Current Off-Site Sources of Nitrate <br /> We recognize that septic systems,agriculture, and dairies in the area maybe the most significant. <br /> sources of nitrate. Septic-tank use in the vicinity is discussed in.Section 3.4 of the SSS. <br /> The water sample was analyzed for nitrate and DBCP. Nitrate was found.at 114 mg/L-NO3,which <br /> is-above the maximum contaminant level (MCL) set by the US EPA of 45 mg/L-NO3. DBCP was <br /> not detected in the water sample. .-.---- <br /> Though <br /> ample. . --_. <br /> Though the water sample indicated elevated nitrates, this condition is not unusual for a shallow <br /> water wells in some areas of San Joaquin County. We recommend that the well be inspected-and <br /> EHD be consulted to determine whether the well could be repaired. We recommend not using the <br /> well for drinking water. <br /> 3.2 Contribution of Rainfall <br /> - An estimate of the quantity and quality of rainfall was required for the nitrate loading analysis. An <br /> 'estimate of potential deep percolation of rain water recharge into the ground is required for the <br /> ® <br /> nitrate loading calculation: Since the site'is fairly sandy and rapid percolation rates were measured <br /> I during the percolation test we will make the assumption thatinearly all the rainfall will infiltrate the <br /> ground fairly rapidly. Therefore,we estimate that roughly 90 percent of the rain fall will enter the <br /> ground as recharge. The 10 percent reduction is to allow for some evaporation and transpiration of <br /> Plants. Runoff is not expected. This method is not appropriate for sites which do not have <br /> relatively high infiltration rates. <br /> 3 <br />