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REMEDIATION TESTING AND DESIGN March 29 , 1993 backfilled U�'T Fit The test was conducted for appro..imately 6E minutes and semi-stable vacuum influence conditions was indicated The stabilized flow rate for VW-2a was 29 scam with a vacuu-n `f 10 inches of mercury ' During this test, significant vacuum influence wa3 noted in prDbes within the UST and only -light vacuum influence in one other probe (P-5 ) Vacuum influence was noted in only one monitor well (MW- 3 ) Figure 5 is a plot of the vacuum Inf luence in the "a" zone during "a" zone extz action from VW- 2a ThIs figure shows good vacuum influence in the "a" Lone over a large part of the site Figure 6 is a plot of the vacuum influence in the "b" zone during "a„ zone e}-traction from VW-2a. This plot shows goc,d influence In the "b" zone with a 2lightly smaller areal extent than that of the "a" zone The relatively low vacuum in well Via'-2U indicates that there is a good seal between the screens of VW-2a and VW-2r) Table 4 presents VEFT field data foi extraction from well VW-2b. The general result of this test showed that vacuum extraction works well in the "b" zone and induces vapor flow within the "a" zone , from the zone near the water table and within the backfilled UST pit E:_traction from VW-2b was conducted for approximately b5 minutes and stable vacuum influence conditions were not quite achieved Llacul um and flow rate in VW-2b stabilized at 10 inches of mercury and 35 scfm respectively. Vacuum influence was noted in probes P-7 and P-8 (within the UST backfill ) at levels significantly lower that the VW-2a test A much stronger vacuum influence was measured in monitor well MW-3 and slight influence was also noted in well MW-1 Figure 7 is a plot of the vacuum influence in the "b" :one during "b" zone extraction from VW-2b This plot shows a very strong influence ever most of the site . Figure 8 is a plot of the vacuum influence in the "a" zone during "b" zone extraction from VW-2b This plat shows strong vacuum influence in the "a" zone over most of the site The center of vacuum influence in the "a" zone as shown on Figure 8 is about 20 feet west northwest of the extraction well This off- centered feature is strong evidence that the seal between the well screens of VW-2a and VW- 2b is very good. Also , vacuum influence in the "a" Lone is stronger during "b" zone extraction than during "a." zone extraction ( compare Figure 5 and Figure 8 ) . Table 5 presents VEFT field data from the vacuum flow step testing conducted in all of the vacuum extraction wells and monitor well MW-3 The results of this test show that each well is a good extraction point for use during remedial activities The "a" zone wells flowed at a slightly higher rates under equal vacuum conditions than the "b" zone wells All of the vacuum extraction wells performed significantly better than monitoring well MW-3 Figure 9 is a graph of the average flow rates versus average vacuum levels for all of the vacuum extraction wells . This graph shows a nearly, linear rElationship between flow rates and required vacuum lsvels r 4