SITE INFORMATION AND CORRESPONDENCE FILE 1

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the installation of the recovery and observation wells ($11,300) and recovery/treatment system rental ($1500). The wellinstallation figure includes the cost of underground utility clearance. Less significant expenditures were for propane tank rental and fuel ($600), water tank storage rental ($450), and well head fabrication materials ($250). Table 3 summarizes the EVR pilot study costs. The cost to purchase the recovery/treatment system used in the EVR pilot study is approximately $45,000. The maximum propane fuel consumption rate is about 1.5 gallons per hour. i The capital expenditure required to add EVR to an existing pumping well is relatively insignificant. In an example in which groundwater is presently recovered from a well with a pump, the minimal hardware requirement is a 100 to 300 standard cubic feet per minute (scf n) regenerative blower ($1900 to $4000), rotron water knock or centrifugal water separator ($650 to $750), well head and associated piping ($250 to $350), and, depending on conditions and regulations, a vapor abatement device. A specific vendor that has a national presence makes pre-fabricated skids with this type of equipment available on a rental basis for about $450 per week, which is especially useful for conducting field tests. Mastroianni et. al., (1994) present design considerations useful in the EVR approach using well pumps and blowers and presents there with case histories. Moreover, Mastroianni et. al., (1994), reports that the cost per pound of vapor- and dissolved-phase contaminant removal ranges from about $6 to $1$ per pound. The range in cost is a function of site specific and hardware parameters. Site specific parameters include geology; hydrogeology; and identities, quantities,.and distributions of contaminants. Hardware parameters include the number of and, capacities of recovery blowers, quantity and types of phase separators, and treatment/abatement equipment. 5.0 Conclusions Results of the EVR pilot study indicate that the sustainable two-fold increase in groundwater production from low yield aquifers predicted by Hackenberg et. al., (1994) is possible. The results from the pilot test corroborates the results of the field test by Mastroianni and Hackenberg (1992). The resulting increase in well recovery allows a reduction in the number of wells required to achieve specific well field production, eliminates dependence on well pulsing strategies, and potentially reduces the duration of remediation. These advantages correlate to cost savings. Groundwater levels monitored in adjacent observation wells showed little deviation from static level throughout the pilot test. This was expected and anticipated. Expected because the water bearing formation was previously shown to be one of low yield, and anticipated because vacuum applied in the manner described controls the groundwater potential. . Experience has shown."that applying a vacuum to enhance groundwater yields increases the slope of the distance versus drawdown curve (drawdown cone) but does not significantly change the groundwater radius of influence" (Hackenberg et. al., 1994). This is the reason 520