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Extraction flow rates ranging from 3 6 to 15 acfm at vacuums ranging from 37 to 93 inches of H2O were achieved at extraction well VW-2D The highest vacuum responses (0 12 to 0 25 inches of H2O)were observed at well VW-3, located approximately 19 feet from VW-2D Moderate vacuum responses were observed in wells VW-4, MW-3, VW-1 S and VW-1 D, located approximately 23 to 40 feet from VW-21D Negligible vacuum responses were observed in wells MW-2 and MW-5, located 50 and 72 feet from VW-21D, respectively For the majority of the observation wells, vacuum responses increased as the applied wellhead vacuum was increased Concentrations of TPH-as-Gasoline vapor extracted from VW-3 ranged from 43,000 to 45,000 mg/m3 and remained relatively stable during the test Concentrations of TPH-as-Gasoline vapor extracted from VW-21D ranged from 21,000 to 46,000 mg/m3 Using standardized flow rate data, the calculated daily TPH-as-Gasoline mass extraction rates achieved during the VET ranged from 13 6 to 57 pounds per day (ppd) per well Results of the soil gas analyses for the collected gas samples and the mass extraction data are included on Table 5 3 3 3 VET Data Evaluation ' Maximum vacuum responses recorded during the testing of extraction wells VW-21D and VW-3 ranged from 0 25 to 0 40 inches of H2O at extraction flow rates of 12 2 and 14 1 scfm, respectively These maximum vacuum responses were measured at a distance of 19 feet from the respective extraction wells For the purpose of estimating an effective radius of influence ' (ROI), a minimum vacuum cut-off of 0 2 inches of H2O has been selected Based on the VET field data, vacuum responses of 0 2 inches of H2O occurred within an average distance of 28 feet from the extraction test wells These vacuum responses are also associated with the higher test flow rates ranging from 12 to 14 scfm 1 Wellhead vacuums during the test ranged from 37 to 93 inches of H2O These relatively high wellhead vacuums at low test flow rates (3 6 to 17 acfm) are reflective of the relatively low permeabdrties associated with the silt and clay based sediments within the vadose zone Usinga conservative) selected ROI f y o 20 feet, each extraction well is expected to have a ' capture zone of approximately 1,200 square feet (so Site investigation soil analytical data was used to estimate the maximum lateral limits of residual TPH-as-Gasoline in vadose zone and capillary fringe soil (Figure 6) It is estimated that the lateral plume limits exist within a 60-foot by 60-foot area, for a total required remedial coverage area of approximately 3,600 sf Based on the VET vacuum response data, a minimum of 3 vapor extraction wells (3,600 sf of plume area at 1,200 sf per well) are required for remedial coverage 13