SITE INFORMATION AND CORRESPONDENCE FILE 1

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i Because EVR induces and/or increases air movement in the unsaturated zone, it is conceived that EVR may be beneficial to SVE remediation and in-situ bioremediation. With SVE, as described by Brown (1994), Christenson et. al. (1989), and Struttman and Holderman (1992), the vacuum used to recover soil vapors could result completely, or partially, from the application of EVR. With bioslurping and/or bioventing, as described by Brown (1994), Capuano and Johnson (1996), Downey and Hall (1992), and Yancheski and McFarland (1992), EVR methodologies can be applied to optimize bio-slurping system operations and subsurface air movement induced by the EVR vacuum could be used to supply additional oxygen to beneficial microbes. 2.0 Procedures This section presents the methods and equipment used in the EVR pilot test. 2.1 Test Preparation Test preparation included test design, recovery and observation well construction, well head fabrication, and vacuum and treatment equipment selection. 21.1 Test Design The test was devised to examine the potential for increasing groundwater production from the low yield aquifer at the test site and the viability of a groundwater recovery system that would riot require downhole pumps, timers, or downhole level switches. With respect to increased water production, the goal of the pilot test was to maintain a discharge rate of 1 gpm or better, which represents a two-fold increase over the measured values from non-EVR pumping and conventional vacuum recovery. With respect to downhole pumps, switches, or timers, the goal was to reduce operation and maintenance (O&M) requirements in the permanent remediation system. Presently, most pump and treat remediation systems in low yield aquifers require the use of numerous wells which are often controlled with groundwater level sensing switches or timers. The planned duration of.the test was 72 hours and evaluation of the resultant data indicated that this was an appropriate test duration to examine efficacy and gather information necessaryfor future design. SVE remediation of the contaminated vadose soils at the proximal end of the dissolved-phase groundwater plume was underway at the time the EVR pilot study was conducted. The contaminated vadose zone soils are comprised of well graded gravel amenable to this type of treatment. The EVR pilot test was conducted at the distal end of the groundwater plume. The test was conducted and test wells were place with the understanding that a successful the EVR final design would incorporate groundwater recovery from 2 or 3 points, rather than the 6 or more that would be required with conventional pumping. 2.2.2 Test Well Construction It wasdetermined that one recovery well and four observation wells were necessary to conduct the pilot test. Three of the observation wells were placed up gradient of the recovery wells at distances of 5, 12, and 20 feet. An existing monitoring well located 40 feet cross gradient from the recovery well, was used as a fourth observation well. 517