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A ALIN California Regional Water Quality Control Board 15365 January 30, 2003 Page 2 PREVIOUS INVESTIGATIONS AND REMEDIATION OF RECENT RELEASES ST Service reported a release of gasoline from aboveground storage tank (AST) No. 3301 in March 2002. ST Services took the tank out of service immediately upon discovery of the release. Fuel stored in the tank was transferred to other ASTs at the facility and absorbant pads were placed in the spill area to contain and remove visible product. A cracked weld in the base was identified and repaired. ST Service discovered a second release of gasoline in April 2002 from AST No. 3302, located southeast of AST No. 3301 (Figure 2). The tank was taken out of service immediately upon discovery of the release. Fuel stored in the tank was transferred to other ASTs at the facility and absorbent pads were placed in the spill area. A failed welding seam in the base was identified and repaired. A release of diesel was reported from AST No. 1503 in June 2002. During a pipeline delivery, the capacity of the tank was miscalculated, resulting in an estimated 1000-gallon release of diesel fuel. Absorbent pads were placed around the tank. Phillips Services was contracted to excavate and dispose of fuel-impacted soil around the tank. Secor conducted an assessment of the soil and groundwater quality around AST Nos. 3301, 3302, and 1503 in August 2002. Results were presented in a report prepared by Secor titled "Additional Site Assessment" and dated October 28, 2002. The results of the assessment are summarized below by tank. AST No. 3302: Five geoprobe borings were advanced adjacent to AST No. 3302. "Fresh" separate phase product was observed in borings ST/SB-1, ST/SB-2 and ST/SB-3. Separate phase product was not identified in borings ST/SB-4 and ST/SB-5. The borings defined the extent of the product to the south. However, the extent of separate phase product was not identified to the north, east and west of the tank. Soil samples were collected to depths up to 25 feet below grade. Soil concentrations were elevated in the 4-foot samples and decreased significantly with depth, providing adequate vertical definition of the impacts of the recent release. AST No. 3301: Three borings consisting of a geoprobe boring to 25 feet (ST/SB-6) and two hand-augered borings to 10 feet below grade (ST/HA-1 and ST/HA-2) were advanced adjacent to AST No. 3301. Separate phase product was not observed in the borings. Concentrations of petroleum hydrocarbons and additives in soil were low relative to the concentrations detected in the shallow soil samples collected adjacent to AST No. 3302, indicating that the recent fuel release has not significantly impacted soil near AST No. 3301.