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Cheaper#76,890 N.Main 5t,Manteca,California December 22,1995 Page 2 • encountered at 13 feet below ground surface. All groundwater samples were analyzed for total petroleum hydrocarbons as gasoline (TPH-g) and benzene, toluene, ethyl benzene and xylenes (BTEX). All samples were non detect except for benzene, detected at 3.5 parts per billion (ppb) in MW-1 and 13 ppb in MW-3 I On November 13, 1987, Kleinfelder requested to dispose of purge and sample water collected from the wells. The purge and sample water collected Apnl 28, 1987 was non detect. On June 21, 1988, Kleinfelder report documented that groundwater samples collected May 27, 1988 were non detect The depth to groundwater was 20 feet below ground surface. In a November 12, 1990 report, Dames and Moore documented that groundwater samples were collected on October 24, 1990. All samples were non detect Depth to groundwater was 25 3 feet below ground surface. A fourth monitoring well was installed at the site on September 6, 1991, by Parker Environmental Services. Soil samples analyzed from the boring were all non-detect for TPH-g and BTEX. Groundwater samples obtained on September 11, 1991 from all four monitoring wells were also non-detect for TPH g and BTEX Depth to groundwater was 28 to 29 feet below ground surface. • A pump test was done by Parker Environmental Services at the site October 15-16, 1991, and it showed that all four monitoring wells are in the same aquifer. A groundwater sample was obtained from MW4 on January 10, 1992. Groundwater depth prior to removal was 24.65 feet, and the well bottom was measured at a depth of 37.77 feet. Approximately ten gallons was removed by bailer and placed in 5-gallon buckets, which were stored on-site in the fenced loading area. After bailing, groundwater depth was 27 75 feet. The sample was non-detect for TPH-g and BTEX. On May 19, 1992, four borings were advanced to determine if residual soil contamination remained in the side walls of the excavation of the former tank pit. Eight soil samples were obtained from four borings around the former location of the underground tanks and gas island. The samples were analyzed at a State Certified environmental lab for TPH as gasoline with BTEX. One sample from 2 feet depth at B-1 contained TPH as gasoline at 2 5 ppm, with toluene, ethylbenzene and xylenes all detected less than 1 ppm. The source of this contamination was concluded to be surface spills leaching through the asphalt. Benzene was not detected. All other soil samples were non-detect for TPH-g and BTEX. Parker Environmental Services, 190 East 7th Street, Pittsburg, CA 94565-2317 Phone (510) 439.1024 Fax (510) 439-2566