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POTENTIAL GROUNDWATER IMPACTS ASSOCIATED WITH THE LEC POTABLE SUPPLY WELL <br /> 2. Vertical hydraulic gradients will be estimated annually using the existing shallow <br /> groundwater monitoring wells <br /> 3. A sampling port will be installed at the well and the well will be sampled for general <br /> chemistry parameters,nitrates, and coliform at least annually. <br /> Given the low production rate of the proposed potable well relative to what the aquifer is <br /> capable of producing,the overall effect on local groundwater levels is expected to be <br /> negligible. An extensive monitoring well network exists for several miles surrounding the <br /> WPCF,allowing actual water level and water quality effects to be observed. <br /> Local estimates of aquifer properties are not available for detailed evaluation of potential <br /> changes in groundwater levels during operation of the onsite potable well. However, <br /> C2VSIM, a Central Valley groundwater model recently developed by the Department of <br /> Water Resources,used an input value for hydraulic conductivity of approximately 40 feet <br /> per day for the area near the WPCF. Estimating that the aquifer thickness at the WPCF is 500 <br /> feet, a well pumping at an estimated rate of 10 gallons per minute would have a drawdown <br /> of between 0.1 and 0.2 feet. That drawdown would be anticipated to return to static <br /> conditions within seconds of the pump being turned off. It is assumed that a holding tank <br /> will be installed near the well head and that the well will pump at a higher rate than needed <br /> for only the period of time it takes to fill the tank and maintain system pressure. Operation <br /> of this well is not expected to have any measurable effect on production wells or surface <br /> water bodies within 0.5 mile of the LEC potable well or contribute to the migration of <br /> groundwater contaminants. <br /> References <br /> California Department of Water Resources (DWR). 2006. San Joaquin Valley Groundwater <br /> Basin. Bulletin No. 118. <br /> City of Lodi. 2006. City of Lodi White Slough WPCF Soil and Groundwater Investigation <br /> Existing Conditions Final Report. <br /> http://www.lodi.gov/public works/pdf/Groundwater%201nvestigation%2OReport/Chap <br /> ter%202%20Facility%20Description.pdf. Accessed July 14,2008. <br /> GROUNDWATER TECHNICAL MEMO 2 <br />