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D ' ASSOCIATES I NC 442 Soil Excavation and Groundwater Remediation ' Excavation of shallow soil contamination and on-site aeration or off-site disposal to a certified waste disposal facility would remove the potential source for further groundwater contamination ' The excavation would be backfilled with clean material and resurfaced to match the existing site conditions Additionally, standing water in the open excavation can be remediated by pumping the water into an on-site holding tank for either on or off-site treatment and/or disposal This ' would remove some of the impacted groundwater from the site ' 43 In-Situ Soil Vapor Extraction with Groundwater Extraction and Treatment In-situ soil vapor extraction (SVE) has proven effective in reducing volatile organic compounds ' (VOCs) and certain semi-volatile compounds in soil In brief, air is extracted from the unsaturated zone, carrying trapped and dissolved contaminants If necessary the effluent air can be treated using a variety of vapor treatment options SVE performed in conjunction with IIS ' groundwater extraction and treatment is even more effective A dedicated pump is placed in a ' groundwater monitoring well and groundwater is extracted 24 hours a day, treated, and then discharged The extraction of the groundwater effectively lowers the groundwater elevation exposing impacted soils, which can be remediated by SVE The advantages of SVE with groundwater extraction and treatment include ' • Short treatment times, usually 1 to 3 years under optimal conditions • Readily available equipment and easy installation ' . Implementation with minimal disturbance to above ground activities • Can be used under buildings and other locations that cannot be excavated ' In order to determine the effectiveness of SVE and groundwater extraction and treatment, pilot scale studies would first need to be performed at the site Data provided by a pilot study is ' necessary to properly design a full-scale SVE and/or groundwater extraction and treatment system Pilot studies also provide information on the concentration of VOCs that are likely to be extracted during the early stages of the operation ' Pilot testing would require the installation of three vapor wells to depths of 15 to 20 feet bgs, and a groundwater extraction well to a depth of approximately 25 to 30 feet bgs Once these wells ' were in place, appropriate equipment would be plumbed to these wells and a pilot scale study will be performed, then the SVE and/or groundwater extraction and treatment system would be designed, installed and operated until remediation is complete ' 5.4 REMEDIATION ALTERNATIVES EVALUATION Each of the alternatives presented above were evaluated according to the following criteria w W50fteports\CAP doc 5 1