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3 3 1 Test Procedures On May 9, 1995, GTI performed an on-site vapor extraction pilot test (VET) to collect site specific data and evaluate the feasibility of using vapor extraction as a soil remediation alternative The VET had three main objectives (1) to measure the extraction flow rates that can be achieved from the on-site vapor extraction wells, (2) to measure the petroleum hydrocarbon concentration of extracted vapors, and (3) to obtain vacuum response data and estimate a radius of influence for the design of a vapor extraction system The VET system consisted of a VR Systems Model V3C internal combustion (IC) engine equipped with a vacuum pump, instrumentation for measuring process flow rate and vacuum, and magnahelic gauges to measure vacuum response in observation wells During the VET, vapor extraction wells VW-3 and VW-21D were used for vapor extraction purposes and up to eight observation wells were used as monitoring points The IC engine blower was used to apply a vacuum to the extraction test wells and induce air-flow through the subsurface earth materials Extracted hydrocarbon vapor was pumped through the IC engine for combustion treatment, prior to ambient venting The extraction tests for wells VW-3 and VW-21D lasted approximately 2 hours each Flow rate and vacuum data for the extraction well process flows and the vacuum responses in the observation wells were recorded and are summarized on Table 5 Vapor samples were collected into TedlarTrm air sample bags using a sample pump located between the extraction well and the blower The vapor samples were sealed in the bags and labeled with the sample number, date and time of collection The vapor samples were transported to Sequoia Analytical and tested for the presence of TPH-as-Gasoline by Modified EPA Method 8015 and BTEX by EPA Method 8020 3 3 2 Vapor Extraction Test Results During the VET, extraction flow rates ranging from 7 to 17 actual cubic feet per minute (acfm) at vacuums ranging from 40 to 82 inches of H2O were achieved at extraction well VW-3 The highest vacuum responses (0 17 to 0 40 inches of H2O) were observed at well VW-2S, located approximately 19 feet from VW-3 Moderate vacuum responses (0 10 to 0 26 inches of H2O) were observed in wells VW-4, VW-1 S and VW-1 D located approximately 35 feet from VW-3 Negligible vacuum responses were observed in wells MW-2 and MW-5, located 40 and 90 feet from VW-3, respectively For the majority of the observation wells, vacuum responses increased as the applied wellhead vacuum was increased • 12