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FLUOR DANIEL GTl Groundwater Monitoring Well Abandonment All 31 site-related wells will be abandoned in accordance with guidelines set forth in California Department of Water Resources Bulletins 74-81 and 74-90. Verbal approval from the SJCPHS has been granted to drill out the casings of wells located in the vicinity of the former underground storage tanks (USTs).The remaining 18 wells will be abandoned using a pressur"routing technique and then drilling out the top three feet of well casing. Fourth quarter 1995 groundwater monitoring data indicate that total depths of the wells at the site range from 45 to 78 feet below ground surface (BGS). Prior to pressure-grouting, each well casing and screen will be checked for obstructions and cleared as needed. A truck-mounted drill rig or a jack hammer will be used to remove the monitoring well traffic boxes and the recovery well vaults. Eight-inch-diameter hollow-stem augers will be used to drill out the casings for the wells constructed of 2-inch-diameter well casing, and 10-inch-diameter augers will be used to drill out the wells constructed with 4-inch-diameter PVC casing. After drilling out the casings for wells MWA, MW-3, MW-4,MWA 7A,B, and C, neat cement, mixed with 3 to 5 percent bentonite,will be pumped from the bottom of each boring to grade via a one-inch-diameter schedule 80 PVC tremie pipe. At remaining well locations, pressure will be applied to the top of each casing to push the cement through the screened interval. The first three to five feet of well casing will be overdrilled using 10-inch-diameter hollow stem auger. The resultant 10-inch-diameter borehole will be backfilled to grade with a neat cement/bentonite grout. Recovery well RWA and pump well PW-3, constructed of 12-inc-diameter low grade carbon steel, will be destroyed by perforating or ripping the well casing and pressure grouting through the screened interval.The upper three to five feet of casing will be removed and the resultant borehole will be backfilled to grade with neat cement mixed with 3 to 5 percent bentonite. All well-related materials, including well casings,well boxes,vaults, and associate concrete,will be segregated from the well annulus material and transported to a local landfill. All well annulus material will be loaded into a soil bin to be sampled and analyzed by a State-certified analytical laboratory for total petroleum hydrocarbons as gasoline (TPH-G); and benzene,toluene, ethylbenzene, and total xylenes (BTEX),following EPA method 8015/8020; and total lead, following EPA method 6010, for proper characterization and disposal Report Preparation A letter report will be submitted upon completion of the field activities. The report will summarize the methods used for well destruction and document the proper disposal of the well-related materials and soil. 0290aban.wkp(S1N-8.1) Work Plan for Groundwater Monitoring Well Abandonment July 19,19W The Southland Corporation,9110 Thornton Road,Stockton,CA 2