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i Kennedy/Jenks/Chilton Backfill Activities The four excavations (Areas 1, 2, 3 and 4) were backfilled with clean imported fill material on 10 May 1990 Approximately 120 tons of material was imported to the facility. The excavations were backfilled and compacted with a Case model 580 K backhoe. TANK REMOVAL SURVEILLANCE ' On 12 April 1990, prior to removing the 1,000-gallon underground diesel fuel storage tank, fluids remaining in the tank were pumped out. This work was performed by H & H Environmental , a subcontractor to Peregren. ' Approximately 55 gallons of fluid was pumped from the tank and trans- ported under a Uniform Hazardous Waste Manifcst to the H & H Environ- mental yard for either disposal or recycling A copy of the manifest is ' provided in Appendix D The tank was uncovered on 18 April 1990 using a Case model 580 K backhoe in preparation of its removal on 19 April 1990 Soil removed by the ' backhoe was stockpiled adjacent to the excavation and stored on plastic sheeting Only enough soil was excavated so that the tank could be quickly removed during agency inspection. Soil staining was not noted during uncovering of the tank. On 19 April 1990, the tank was removed. Representatives of the San Joaquin Local Health District and the Stockton Fire Department were present during the tank removal . Prior to removing the tank from the excavation, the tank was purged with dry ice to create an inert atmo- sphere inside the tank After the tank had been allowed to sit for approximately 45 minutes to an hour, it was checked with a lower explosive limit (LEL) meter to confirm that the tank had been purged of explosive vapors. The tank was then removed from the excavation, swept ' clean of soil , and inspected for signs of corrosion or leakage. The diesel tank was manufactured of steel . There was no sign of corrosion or leakage from the tank. Later that day, the tank was transported under a Uniform Hazardous Waste Manifest by H & H Environmental to their ' facility in San Francisco for destruction or scrap metal recycling. A copy of the manifest is included in Appendix D ' After the tank was removed, the excavation was visually inspected and soil samples collected by a Kennedy/Jenks/Chilton representative. It was noted that the excavation was approximately 16 feet wide by 12 feet ' long, and had an average depth of approximately 10 feet. No staining was observed in soil below the tank After the tank was removed, soil vapors were monitored utilizing an ' organic vapor analyzer (OVA) . The presence of organic vapors in soil was determined by the headspace analysis method whereby soil was placed in a plastic jar and tightly covered with aluminum foil . The sample was placed in a warm area for approximately 10 minutes to promote volatil- ization After 10 minutes, the probe of the OVA was inserted through the aluminum foil into the container headspace and the meter read. WPI13 3.3 882526.01