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on each well for 30 minutes, and induced vacuum changes were monitored in the observation wells The extraction flowrate from well VW-1 ranged from 105 cfM to 109 cfin at an applied vacuum of 30 ' inches of water The extraction flowrate from well VW-3 ranged from 113 cfm to 118 cfin at an applied vacuum of 30 inches of water After 30 minutes of operation a vapor sample was collected from each well for laboratory analysis ' Vapor samples were collected through a 1/4-inch Teflon sample line connected to a stainless steel wellhead fitting, and collected in Tedlar sample bags Teflon tubing was used to minimize sample loss ' through adsorption and the possibility of distorted results from sample lines contaminated by previous test runs The samples were sent to Sequoia Analytical for analysis of TPHg and BTEX using EPA Methods 5030/8015/8020 4.4.3 Soil Vapor Extraction Test Results ' During the long term extraction test from VW-2, well head flowrate and vacuum readings recorded were 100 to 105 cfin and 30 inches of water, respectively Induced vacuums in observation wells VW- 1 and VW-3 were almost instantaneous due to the porous soil conditions of the site As the flowrate ' was increased to over 100 cfm, the observed induced vacuums increased to vacuums ranging from 0 72 to 12 inches of water These values were observed at a vacuum of 30 inches of water The achievable flow of 100 cfin is considered to be high but not unusual for such porous soil conditions ' VW-1 is located 24 5 feet from extraction well VW-2 and VW-3 is located 315 feet from VW-2 The vacuums and flow rates achieved during the short term tests on VW-1 and VW-3 were similar to those achieved during the long term test IEgh air flow rates ranging from 105 to 118 cfin at applied vacuums of 30 inches of water were achieved The induced vacuums in the observation wells ranged from 0 1 inches of water uutiaHy to as much as 1 15 inches of water Utilizing induced vacuum and distance measurements obtained during the VET, an effective radius of ' influence was estimated for the vapor wells at the site RESNA assumes that an induced vacuum of 0 25 to 0 5 inches of water should be sufficient to induce subsurface airflow within the zone of influence The flow rates, induced vacuums, and applied vacuums recorded dunng each of the three vapor extraction tests suggested that the subsurface conditions were relatively homogeneous and that short ' circuiting through the former tank pit was negligible The induced vacuums recorded in the observation wells suggest the effective radius of influence exceeded the distance between the observation weUs (over 30 feet) This was sufficient to cover the area where significant levels of petroleum hydrocarbons remain in the soil The results of laboratory analyses of influent vapor samples indicated that vapor TPHg concentrations ' were nondetectable (<5 0 milligrams per cubic meter [mg/m3)) in well VW-1 and 40 mg/m3 in well VW-3 Concentrations of vapor phase TPHg in well VW-2 increased from 1 10 mg/m3 in the sample collected at 15 minutes to 230 mg/m3 in the sample collected at 90 minutes The long term test was w\95141Vjuaflyl4q.1993 doc 7 • SMTH 1