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3rd Quarter Report - Beacon Station #695 3 December 1992 Although vapor concentrations generally declined at the individual extraction points during the 3rd quarter, concentrations remained above several thousand parts per million (ppm) at many locations. This suggested that a significant residual contaminant mass was still present at the conclusion of the quarter. During the 3rd quarter the ongoing remedial program eclipsed the 50,000 pounds extracted mark, indicating that significant progress has been made in evicting the contaminant mass from the subsurface. Over 16,000 pounds of hydrocarbons were extracted during the 3rd quarter alone. Efforts were made to increase the extraction flowrate from the ground by completely closing ambient dilution and by eliminating one of two undersized, restrictive piping connections between the systems three manifold boxes and the vacuum pump. On 22 September, the final date of monitoring during this quarter, the efforts to improve system performance had been successful in increasing the hydrocarbon extraction rate to 263 pounds per days (lbs/day) . II . RECOMMENDATIONS To further increase the flowrate from the soils, the second restrictive connection between manifold boxes should be eliminated as soon as possible. If further improvements are still desired, other options include repulleying the pump or replacing the vacuum pump drive motor with a higher rated unit Given the level of residual hydrocarbons observed at the conclusion of the third quarter, it is likely that the current program utilizing the catalytic incinerator will need to be continued at least through the end of the 4th quarter. III. INDIVIDUAL MONITORING EVENTS The following section describes how the system was adjusted during each monitoring within the performance limits of the equipment and the compliance limits of the operating permit issued for the system 1 July 1992 Monitoring: The SUES was apparently shut down on 18 June while routine groundwater monitoring activities were being undertaken. The system was restarted on 30 June and allowed to purge a full day prior to monitoring on 1 July. On 1 July, vapor concentrations remained quite high at many extraction points with a region of 10,000+ ppm concentrations present between the gasoline and diesel pump islands. Side by side wells MW-3 and MW-10, which appeared to be near the heart of the plume, both had 10,000+ ppm concentrations suggesting that high levels of soil gases were present in -2-