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butyl ether(MTBE) following EPA Test Method 8020 Soil samples collected from the depths of 30 and 52 feet bgs in boring VM-I were also tested for bulk density, moisture content and organic carbon content 28 Well Survey 1 The elevations of the tops of each well casing for the previously restored wells MW-9, MW-13, MW-14, MW-16, MW-19, MW-20 and MW-24, new wells VW-1, MW-11, MW-25 and MW-26 and existing well MW-12 were surveyed relative to Caltrans Monument I (elevation = 21 57 feet MSL) by a Geocon registered civil engineer The survey data for each well is presented on Table 3, Summary of Groundwater Elevation and Analytical Data 29 Vapor Extraction Pilot Test ' Geocon performed an on-site vapor extraction pilot test (VET) on August 15, 1996, 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 vapor extraction rates that can be achieved ' from the vapor extraction well, (2)to measure the petroleum hydrocarbon concentration of extracted vapors, and (3) to estimate an effective radius of influence (ROI) for the vapor extraction well for future engineering design The VET system consisted of a 2 0 horsepower Gast regenerative blower powered by a portable 220- volt generator, one 200-pound granular activated carbon (GAC) bed, instrumentation for measuring process flowrate, vacuum and temperature, a diaphragm valve for extraction well flowrate selection and control, and Dwyer MagnahelicTM gauges to measure vacuum response in observation wells ' The VET system was connected to the wells using flexible hose equipped with quick disconnect camlock fittings ' Vapor extraction well VW-1 was used for vapor extraction purposes while wells VM-1 and VM-2 were used as monitoring points during the VET The blower was used to apply a vacuum to VW-I ' and induce air flow through the subsurface earth materials Extracted hydrocarbon vapor was pumped through the GAC bed for treatment prior to ambient venting The test lasted approximately ' 2 5 hours and maintained a flowrate of 60 standard cubic feet per minute (scfm) Vacuum, temperature and flowrate data for the extraction well process flow and the vacuum response in monitoring wells VM-1 and VM-2 were recorded at approximately 15 to 30 minute intervals and are ' summarized on Table 4 ProjectNo 58100-06-18A -7- December 9, 1996