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3rd Quarter Report -- Beacon Station #695 3 December 1992 <br /> The pattern of high concentrations within the plume shifted somewhat <br /> towards the southwest with the area of 10,000+ ppm concentrations between <br /> the pump islands expanding to include RW-1 for the first time. <br /> Concentrations had been increasing at RW-1 ever since being reopened on <br /> 28 July 1992. <br /> Concentrations at the individual extraction points generally decreased <br /> with MW-1 declining from 10,000+ ppm on 13 August to 5,000 ppm on this <br /> date. Well MW-4 was closed due to low concentration raising the influent <br /> to 1,575 ppm. <br /> 9 September 1992 Monitoring. <br /> The system operated continuously since the previous monitoring. <br /> Concentrations generally declined at the individual extraction points <br /> with the area of highest concentrations between the pump islands <br /> shrinking as RW-1 declined from 10,000+ ppm to 5,000 ppm. The secondary <br /> area of 10,000+ ppm concentrations east of the tank field was again <br /> absent. <br /> There were no extraction valve positions changed on this date with all <br /> valves except MW-2, MW-4 and MW-15 remaining open. <br /> With concentrations declining, ambient dilution was closed for the first <br /> time raising the vacuum to 9.3" Hg; the highest on record. The influent <br /> concentration increased to 1,948 ppm according to the laboratory <br /> analysis. <br /> Although the equipment was operating near the limits of the system exit <br /> temperature and amperage loading, the system still appeared to be <br /> underperforming in terms of flowrate. Measures to increase the flowrate <br /> were considered. A dirty filter was removed from the influent pipe <br /> allowing the air flowrate from the ground to be increased to about 220 <br /> scfm. This appeared to be the maximum air flow the system could draw <br /> from the ground. <br /> Upon examination of the system installation records, two undersized <br /> restrictive pipe connections were discovered: one above ground and the <br /> other below. A site visit was scheduled to first remove the accessible <br /> above grade restriction and see if this had a favorable effect in <br /> increasing the flowrate. <br /> 21 September 1992 Servicing Visit: <br /> The system operated continuously since 9 September and was temporarily <br /> shut down for servicing on this date. The accessible above ground <br /> restrictive pipe connection was corrected and a new filter was installed. <br /> The system was restarted and new flow measurements were taken. <br /> -5- <br />