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If evaluations indicate that a continuous groundwater pumping system is needed, selected wells will be connected to the "ConVault" treatment system. Groundwater recovery lines, from the wells to the treatment compound, will be 318" nylon tubing inside buried 3" PVC pipe, for double containment considerations. _ The groundwater recovery lines will be plumbed to an aboveground polyethylene sediment trap. The contaminated groundwater is pumped from the sediment trap with a centrifugal pump and sprayed into a "ConVault" 1000-gallon aboveground tank for spray aeration. The "ConVault" tank is a double contained steel tank shrouded in concrete. The treatment of the groundwater will occur in batches (300 gallons per five hours). After treatment the water is then dumped from the treatment tank, via the centrifugal pump, through a totalizer water meter. The water is then passed through a chamber containing an LEL meter relay calibrated to shut off the system if vapors from the effluent ever reach the 10% LEL level. The clean treated water is discharged to the three-inch sewer clean out. A visual inspection for leaks on aboveground lines, tanks and double contained system will occur during all site visits. UPDATE STATUS REPORT#40 Interim groundwater treatment started December 1, 1992. LTT was vacuum lifting (purging) monitor wells MW 1, MW2, MW3, MW8 and MWI0 twice a week until May 1993, at that time the purging was reduced to once a week until discontinued on August 30, 1993. Before the well purging commenced, water samples were obtained from the "ConVault" tank aerator before dumping 800 gallons of this treated water to the sewer lateral, see Update Status Report #1. The ConVault sewer discharges occurred on February 4, 1999. 1000 gallons of treated purged well water and condensate was discharged to swere for a total of 22,422 gallons of treated groundwater dumped to the sewer as of February 4, 1999. A continuous LEL reading of the discharge water was observed and noted on the following table. All discharge requirements were met. No treated water was dumped to the sewer during the months of March, April, May, June, July, August, September, October,November, December, 1996, and January, February, April, May, July, August, September 1997, March, May, June and October 1998 and January 1999. The last sampling of the ConVault treated water occurred on January 14, 1999 with results received from the Certified Laboratory, via Fax on February 3, 1999. 2 R-603 WW#40 2109199