Laserfiche WebLink
2.0 INVESTIGATIVE METHODS <br /> 2_1 Vapor Extraction Pilot Test <br /> Geocon performed an on-site vapor extraction pilot test (VET) on August 15, 1996, to collect site <br /> specific data and evaluate the feasibility of using vapor extraction as a soil remediation alternative. <br /> The VET had three main objectives: (1) to measure the vapor extraction rates that can be achieved <br /> from the vapor extraction well; (2)to measure the petroleum hydrocarbon concentration of extracted <br /> vapors; and (3) to estimate an effective radius of influence (ROI) for the vapor extraction well for <br /> future engineering design. <br /> The VET system consisted of a 2.0 horsepower Gast regenerative blower powered by a portable 220- <br /> volt generator, one 200-pound granular activated carbon (GAC) bed, instrumentation for measuring <br /> process flowrate, vacuum and temperature, a diaphragm valve for extraction well flowrate selection <br /> and control, and Dwyer MagnahelicTM gauges to measure vacuum response in observation wells. <br /> The VET system was connected to the wells using flexible hose equipped with quick disconnect <br /> camlock fittings. <br /> Vapor extraction well VW-2 was used for vapor extraction purposes while wells VW-1, MW-1 and <br /> MW-3 were used as monitoring points during the VET. The blower was used to apply a vacuum to <br /> VW-2 and induce air flow through the subsurface earth materials. Extracted hydrocarbon vapor was <br /> pumped through the GAC bed for treatment prior to ambient venting. The test lasted approximately <br /> 1.25 hours and maintained a flowrate of 50 standard cubic feet per minute (scfm). Vacuum, <br /> temperature and flowrate data for the extraction well process flow and the vacuum response in <br /> monitoring wells VW-1,MW-1 and MW-3 were recorded at approximately 15 to 30 minute intervals <br /> and are summarized on Table 4. <br /> Vapor samples were collected in opaque TedlarTM one-liter air sample bags using a sample pump with <br /> t/4-inch tygon-type tubing connected to a labcock sample port located between the extraction well <br /> and the blower. The vapor samples were sealed in the bag and labeled with the sample number, date, <br /> time, and sampler's name. The vapor samples were transported to Excelchem Environmental Labs <br /> and tested for the presence of TPHg following EPA Test Method 8015 modified and BTEX <br /> following EPA Test Method 8020. <br /> Project No.S8100-06-11C -3- December 17, 1996 <br />