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UST Closure Report • • ABF Freight System,Inc. Manteca,California Page 4 Excavation around the UST occurred on March 16 and 17, 1998. Excavated soils were stockpiled next to the excavation site. The depth of the excavation was approximately 11 feet and groundwater was encountered at approximately 10.5 feet. Stained soils were observed at the base of the excavation. 3.3.3 RemovalofUST On March 18, 1998, the UST was inerted with approximately 153 lbs. of dry ice provided by Arctic Ice Company of Stockton, California. A combustible gas indicator was used to confirm that both LEL and OZ levels were below 10% prior to the UST removal. Thompson & Rich Crane Service, Inc. of Stockton, California removed the UST from the excavation. The removal activities were conducted under the observation of CAL INC and County of San Joaquin personnel. The UST was lowered to the ground where it was cleaned and inspected. No identifiable holes were found, however, the UST showed signs of leakage in the comers. Pitting was evident on the underside of the UST. 3.3.4 Excavation Inspection The excavation was to a depth of approximately 11 feet. Groundwater was at a depth of approximately 10.5 feet. Contamination was visually evident on the surface of the groundwater and a hydrocarbon odor was present. Approximately 100 cubic yards of soil stained with diesel was stockpiled adjacent to the excavation. After removal of the UST, the excavation bottom was probed using the backhoe bucket to assess subsurface conditions beneath the UST. The probing confirmed that the UST was not secured to a concrete ballast slab. 4.0 SAMPLING AND ANALYTICAL PROGRAM This section presents a discussion of the soil and groundwater sampling procedures and analytical methodologies that were utilized for the project. All sampling and analytical work conducted on the project was conducted in accordance with the Project Work Plan. The specific laboratory analyses was conducted by North State Environmental Analytical Laboratory of South San Francisco, California, a State of California-approved laboratory. The sampling program consisted of the collection of samples from the following areas: 1) soil samples from the stockpile area collected to profile the soil for disposal; 2) confirmatory soil samples from the excavation bottom to confirm soil conditions at the limits of excavation; 3) soil samples from the dispenser area to determine soil conditions around the associated piping; and 4) groundwater samples from the excavation to assess groundwater conditions. The analytical results are presented in Appendix 3. A description of each type of sampling activity is presented in the • following sections. \\SERVERI\C-DRIVE\PROJECTS\3272\Plans and Reports\UST Closure Report.doc May 21,1998