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R604 :UPDATE 9-MARCH, 1992 <br /> line; indicating no recoverable petroleum hydrocarbon vapors were <br /> available from the wells. After the analysis had occurred the <br /> vapor recovery system was shut off. The second period ended on <br /> January 27 , 1992 . At this time the vacuum recovery system was <br /> restarted and only pulling vacuum from P1 , P3-Swarm and EX wells. <br /> A sample of the effluent of the pumps was then obtained; the <br /> resulting chromatogram shows a flat line; no detectable gasoline <br /> petroleum hydrocarbons. The system was then shut off and <br /> dismantled. <br /> EX <br /> The EX well , tank excavation well, was used during the initial <br /> period of vapor recovery (April 26 , 1991 - June 7 , 1991 ) . It was <br /> then taken off line and used as a vacuum influence well until July <br /> 8 , 1991, due to the lack of petroleum hydrocarbon vapors being <br /> produced from this well. Vapors were then recovered from the EX <br /> well intermittently until the system was initially shut off on <br /> November 21, 1991 . The chromatogram produced from the analysis on <br /> November 21, 1991, shows a relatively flat line, with minor <br /> response probably being attributed to residual peaks from the <br /> previous analysis. As with the other two vadose zone recovery <br /> wells (P1 and P3-Swarm) , this well went through two periods of <br /> "re-equilibration" . The first period ended on December 16 , 1991, <br /> when the vapor recovery system was briefly re-started during the <br />. site visit to sample the ground water monitoring wells . The <br /> resulting chromatogram was a flat line; indicating no recoverable <br /> petroleum hydrocarbon vapors were available from the wells . After <br /> the analysis had occurred the vapor recovery system was shut off . <br /> The second period ended on January 27 , 1992 . At this time the <br /> vacuum recovery system was restarted and only pulling vacuum from <br /> P1, P3-Swarm and EX wells. A sample of the effluent of the pumps <br /> was then obtained. The resulting chromatogram shows a flat <br /> line, no detectable gasoline petroleum hydrocarbons, see Field <br /> Notes and Chromatograms, Appendix C - Update Status Report #8 . <br /> The system was then shut off and dismantled. <br /> VACUUM INFLUENCE <br /> Soil contamination has been documented as being associated with <br /> the pump dispensers and the tank field; as degraded gasoline range <br /> hydrocarbons. Figure 3B shows the outline of the soil <br /> contaminated after over excavation. As was stated earlier, vapor <br /> recovery has removed the petroleum hydrocarbons from the soil and <br /> has greatly reduced the petroleum hydrocarbons dissolved in the <br /> ground water beneath this site. Figures 5A and 5B show the <br /> decline of the ground water plume from December, 1991 to March, <br /> 1992 . These figures represent the field data that shows vacuum <br /> extraction is successfully removing the hydrocarbon contamination <br /> that existed at this site . <br />• <br /> page 8 <br />