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COMMENTS <br /> I. The on-site boring logs surveyed to date provide site-specific information but do <br /> not permit inferences to be made about the regional stratigraphy and hydrogeology. <br /> LVP has determined the depths and screened intervals for 45 regional water supply <br /> wells but has not inspected the boring logs for these wells, which are likely on <br /> record at the Department of Water Resources. LVP should inspect these logs and <br /> should develop a more regional subsurface hydrogeologic model than that presented <br /> in the Phase II report. <br /> 2. The report divides the subsurface into three relatively independent water-bearing <br /> zones: A, B and C, with Zone C being the deepest, most productive formation. <br /> (Based on well drillers' logs, LVP has concluded Zone C is the aquifer in which <br /> many of the regional water-supply wells are completed. ) The geologic cross- <br /> sections do not accurately present the various subsurface formations as recorded <br /> on the boring logs. Although the cross-sections present the site's subsurface <br /> formations as laterally extensive and unbroken between boreholes, the boring logs <br /> do not support this conclusion in several instances. While the boring logs and <br /> geophysical logs appear to agree that the deepest zone is the most transmissive <br /> and substantial , these data do not confirm that the less transmissive zones are <br /> fully independent of one another. <br /> 3. The pumping tests may not demonstrate the water-bearing zones are regionally <br /> independent because the wells used to conduct the drawdown tests appear to be <br /> located near one another. Additional wells completed in water-bearing zones other <br /> than where the extraction well is completed should be monitored in future pumping <br /> tests. <br /> 4. The report does not fully describe the pumping tests, omitting discussion of <br /> important variables. However, the aquifer transmissivities and storativities <br /> estimated at this stage in the ground water cleanup effort are less important than <br /> those needed for the extraction well (s) central to the future ground water <br /> treatment system design. LVP must fully substantiate the Phase II report pumping <br /> test analyses by discussing the following factors and any other relevant factor <br /> not mentioned in this review: <br /> a. The Theis equation is typically used for confined aquifers, while the report <br /> presents the Theis curve for an unconfined aquifer. Although the Theis <br /> equation may be applied in some cases to unconfined aquifers, the report does <br /> not justify so using the equation in this instance. <br /> b. The report should provide the flowrate used to test the deepest water-bearing <br /> zone. <br /> c. The wells may not fully penetrate the water-bearing zones. The report should <br /> discuss the effects of the screened lengths on the pumping tests. <br /> d. The report should discuss the effects of the short time frame over which the <br /> pumping tests were conducted. <br />