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QUARTERLY SUMMARY REPORT 3RD QTR - 1993 (JULY - SEPTEMBER) UNOCAL SERVICE STATION #6348 3788 Tracy Boulevard Tracy, California City/County ID # NIA COUNTY San Joaquin BACKGROUND During removal of an underground waste oil tank in 1990, soil contamination was discovered A portion of the contaminated soil was removed In 1991 four monitoring wells were installed Soil borings delineated the extent of oil contamination in addition to gasoline contamination adjacent to the fill pipe Monitoring Well MW-3 was abandoned on November 24, 1992 in preparation for the removal of the underground fuel tanks The underground fuel tanks and associated piping were removed on December 23, 1992 Overexcavatvon of hydrocarbon affected soil was conducted around the former underground fuel tanks and the pump islands Approximately 1,320 gallons of groundwater were pumped from the tank excavation during the backfill operation Quarterly groundwater monitoring and sampling was conducted on March 17, 1993 No dissolved hydrocarbons were detected in the groundwater from the three remaining monitoring wells at the site RECENT QUARTER ACTIVITIES Quarterly monitoring and sampling of groundwater was suspended during the third quarter 1993 pending the remediation and removal of sod stockpiles which currently cover a significant portion of the site NEXT QUARTER ACTIVITIES Sampling and removal of soil stockpiles, installation of replacement well for MW-3, and resume Quarterly Monitoring and Sampling CHARACTERIZATION / REMEDIAL STATUS S�il contamination delineated? Yes Dissolved groundwater contamination delmeated7 Yes Free product delineated? none Amount of groundwater contaminant recovered this quarter? _0 gal Sod remediation in progress? .Coni leted_01/19/93 Dissolved/free product remediation in progress? No - anticipated start? None - anticipated completion? None CONSULTANT/CONTRACTOR Mittelhauser Corporation 2168RO04 wp 10/05/93