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3rd Quarter Report - Beacon Station #695 3 December 1992 elevated concentrations between the pump islands and east of the tank field again appeared in the data. The apparent decline is at least partially attributed to the fact that a different field instrument (flame ionization detector) was being used while the usual OVA unit was being serviced. In several cases the detector was extinguished due to low oxygen, this understating the actual concentration. The concentration rose slightly in RW-1. Consequently, the valve for RW- 1 was opened, thus providing dilution air to the SHIES from this large, recovery well . RW-1 is a 6" diameter well with a screened interval extending all the way from 33 to 80' below grade. The introduction of RW-1 to the SVES decreased the system vacuum to 5.5" Hg. Well MW-2 was finally cleared of water but remained closed due to low concentration. 13 August 1992 Monitoring: The system operated continuously since the previous monitoring. The familiar plume pattern featuring primary and secondary areas of high concentrations between the pump islands and east of the tank field, respectively, again appeared in the data. There were no extraction point valve positions changed on this date with all valves remaining open except MW-2 and MW-15. Vapor concentrations increased substantially at RW--1 with the laboratory analysis of a verification air sample confirming a high concentration of 3,200 ppm. Concentrations at RW-1 had been non-detect as recently as 16 June 1992 The extraction pump system was operating at 95% of the rated load capacity of the electric drive motor. The system influent concentration increased slightly to 1,500 ppm with the SVES extracting approximately 153 lbs/day of hydrocarbon from the soil . The contract lab analysis of the influent benzene concentration was suspect due to a non-detect result associated with the 1,500 ppm total hydrocarbon concentration. It was noted that the system appeared to be underperforming in terms of flowra+e Measures to increase performance were discussed including checking filters, repulleying, rewiring to 460 volts and possibly using a higher rated drive motor for the vacuum pump. 26 August 1992 Monitoring: The SVES operated continuously until 24 August at which time the system went down apparently due to lack of fuel . The system was restarted on 25 August and the monitoring rescheduled for 26 August to allow sufficient purge time. -4-