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CIARWATER G R O U P, I N C Soil vapors were tested from well RW-1 to evaluate volatile soil gas concentrations These samples were analyzed for TPHg and BTEX by Trace Analysis Laboratory, Inc The sample results from RW-1 revealed 80,000 mg/m3 TPHg and 20,400 mg/m3 total BTEX with the vapor extraction system operating Air sample analytical results are summarized on Table 5 Certified analytical reports are presented in Appendix B The sample from RW-1 indicates that volatilization from the groundwater/air interface is significant Even at low vapor flow rates, hydrocarbon recovery could be successful At the maximum flowrate induced during the test (45 cfm), hydrocarbon recovery rates were approximately 320 lbs/day (53 gal/day) At lower flowrates (-20 cfm), hydrocarbon recovery would still be substantial at approximately 140 lbs/day (23 gal/day) These initial recovery rates should be viewed as maxima because the fduration of the vapor extraction test on RW-1 did not exceed the time needed to extract one pore volume from the zone of soil contamination Approximately a tenth of a contaminated pore volume had been extracted at the time the air sample was collected Even if hydrocarbon recovery rates are an order of magnitude less than those calculated (32 lbs/day vs 320 lbs/day), they would still be great enough to warrant consideration of soil vapor extraction as a remedial alternative 5 3 3 _Soil Vapor Extraction Test Results A soil vapor extraction test with no concurrent groundwater extraction was performed on vapor wells VW-1, VW-2, and VW-3 Vapor wells VW-2 and VW-3 were capable of similar vacuums and flowrates, but vapor well VW-1 produced vacuums and flowrates more similar to RW-1 The maximum vacuum applied to VW-2 and VW-3 was 60 in w c , which generated flowrates of 15 and 10 cfm, respectively The maximum vacuum applied to VW-1 was 60 in w c , which generated a flowrate of 58 5 cfm Vacuums and corresponding flowrates for VW-1, VW-2, and VW-3 are summarized on Table 4 Oxygen concentrations in the extracted vapor were ---1% Percent of lower-explosive-limit for the vapors from VW-2 and VW-3 was approximately 29% Vacuum and flowrate data is included in Appendix E I The effective radii of influence for VW-2 and VW-3 were estimated in the same fashion described for RW-1 The effective radii of influence for VW-2 and VW-3 are approximately 20 feet and 17 feet, respectively Radius of influence data for VW-1 was not collected However, considering that the vacuum versus flowrate characteristics of VW-1 are more similar to RW-1 than VW-2 and VW-3, the radius of influence is probably approximately 30 feet (greater than VW-2 and VW-3, but less than RW-1) Radius of influence data is presented in Appendix E I D-I07, PAR RAP 12 February 21, 1996