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Pks�%leL a A S S O C I A T E S I N C k wed g 11, " On the second day, a long-term vapor extraction test was performed by ATC using vapor well VW3 as the vapor extraction point while monitoring vacuum response in the surrounding wells, MWI, MW2, MW3, MW7, ASI, AS1(d), PZla(s), PZ1a(d), PZlb(s), PZ1b(d), VW1 and VW2 (Figure 3) The test was approximately 4 hours in length Flowrates, applied vacuums, influent and effluent VOC concentrations, and temperatures were also monitored during the test Vapors ' were extracted using an internal combustion (IC) engine equipped with a 5-hp blower and a moisture knockout chamber One influent vapor sample was collected during the test after 0 25 hours of operation Two effluent vapor samples were collected during the test, one after 0 25 hours of operation and one after 3 75 hours of operation Samples were submitted under chain- of-custody to Sequoia Analytical (ELAP #1624) and analyzed for TPHg by EPA method 8015, ' BTEX by EPA method 8020, and MTBE, ETBE, DIPE, TBA, and TAME by EPA method 8260 5.2 Vapor Extraction Test Results ' Results and field readings from the short-term and long-term vapor extraction tests performed on October 31 and November 1, 2001 are summarized in Tables 5 and 6 Copies of field notes are ' contained in Appendix E Copies of laboratory reports are contained in Appendix F During the long-term vapor extraction test on well VW3, extraction flowrates ranging from 25 6 M to 49 3 cubic feet per minute (cfm) resulted in a vacuum of up to 2 6 inches of water in piezometer PZ 1 b(s) located 14 feet away Vapor well VW3 is screened from 51 to 65 feet bgs and piezometer PZ 1 b(s) is screened from approximately 61 to 62 feet bgs A vacuum of up to 0 37 inches of water was observed in well VW2 located 53 feet away from well VW3 and a vacuum of up to 0 27 inches was observed in well VWI located 44 5 feet away from well VW3 All three vapor wells are screened from 51 to 65 feet bgs 1 Based on observed vacuums in the observation wells, the pilot test yielded an estimated radius of influence (ROI) of approximately 50 feet The actual radius of influence for each vapor extraction well will vary depending on subsurface geologic conditions, the extent and distribution of hydrocarbon-impacted soil, and site-specific operating conditions of the vapor extraction system ' The effective radius of influence should be evaluated following the installation and long-term operation of a vapor extraction system During the short term and long term pilot tests, influent volatile organic compound (VOC) vapor concentrations monitored with a flame ionization detector were measured at concentrations greater than 1% resulting in a flame out in the FID meter Lack of oxygen in the airstream prevented additional measurements Laboratory results of the vapor samples indicated that volatile hydrocarbons were detected in the influent samples Approximately 9 pounds of TPHg and benzene were removed during the vapor extraction pilot test as shown below } The average concentration of TPHg in four influent vapor samples collected from wells V W 1 / and VW3 was calculated Using a molecular weight supplied by Sequoia Analytical of 86 27 grams per mole of TPHg, the average concentration by volume was calculated w 1163931reponslrifs doc 10 I