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V �.1 <br /> INCREASED YIELD FROM A SHALLOW AQUIFER USING <br /> ENHANCED VACUUM RECOVERY <br /> William Schaal and Cynthia Labaniego Cox <br /> International Technology Corporation <br /> Martinez and San Jose, California <br /> Abstract <br /> An empirical study shows that a two-fold increase in water production can be obtained in <br /> some low yield shallow aquifers using an enhanced vacuum recovery procedure. In this <br /> procedure, the recovery well is fitted with a specially designed head that provides control <br /> over negative pressure developed inside the entire well. It is the application of vacuum <br /> throughout the entire well that distinguishes this technique from other groundwater recovery <br /> procedures. <br /> Enhanced vacuum recovery represents the progression from conventional non-enhanced <br /> vacuum recovery techniques for well purging and dewatering. The two-fold increase in <br /> production is derived by comparison of the enhanced vacuum recovery technique to both <br /> standard vacuum extraction and well pumping procedures. <br /> The diameter of the recovery well used in this study was eight inches; however, well diameter <br /> is not critical to successful implementation of the enhanced vacuum recovery technique. <br /> Vacuum is applied to the recovery well through a one inch PVC stinger incorporated in the <br /> well head design. The stinger used to administer vacuum also provides the conduit for <br /> groundwater to be brought to ground surface. Groundwater is not lifted in a solid stream, <br /> rather it is entrained with air. <br /> Vacuum may be applied to the recovery well from a variety of equipment. In this study, the <br /> RSI S.A.V.E.m system, which incorporates vacuum for soil venting and to enhance air <br /> stripping, was used to recover groundwater. Groundwater recovery with the vacuum used to <br /> recovery soil vapors and increase stripper efficiency represents a new application for this <br /> system. <br /> Potential advantages of enhanced vacuum recovery include increased well recovery in some <br /> low yield shallow aquifers, reduced number of wells required to achieve specific well field <br /> production, reduced remediation durations, and elimination of labor and down time associated <br /> with operation/maintenance of pumps controlled by level switches or timers, and <br /> supplementation to SVE and bioremediation. <br /> 515 <br />