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FARR ASSOCIATES The soil was taken to Sacramento County Landfill for disposal Weigh tickets are shown in Appendix G Water contained in the storage tank, approximately 450 gallons, was discharged to the sanitary sewer on November 16, 1998, in accordance with the City of Stockton's October 7, 1998 discharge permit Drums that were damaged were cut up for scrap Drums in good condition were recycled to Central Valley Drilling Corporation of Rancho Cordova, California 5.0 DISTRIBUTION OF CONTAMINATION AT SITE 51 Soils Soil samples have been collected from the tank excavations as well as from borings at the Site Analytical results from the tank excavation samples are contained in Appendix A Analytical results from soil samples collected from borings are included in Appendix C, and soil-gas data is contained in Appendix E Figure 7 provides a summary of the concentration of chemicals detected in soil samples from soils not removed from the Site Because most of the soils data were collected between 1990 and 1992, petroleum concentrations have probably decreased significantly over the past seven years This summary indicates that the only compound detected in the vicinity of Tanks 1 and 2 was a single sample containing 78 mg/kg TPH-o from a depth of 5 feet below the product lines The data indicates that there were low concentrations of residual petroleum-range compounds in soil near former Tank No 4 in a vertical layer from approximately 5 to 25 feet in depth However, this contamination resides beneath the existing ice plant building and the railroad right of way Furthermore, the groundwater quality data confirm that this soil contamination has not Isignificantly impacted water quality The data also indicate that there were low levels of toluene in soils in the 30 to 55 foot interval near the Tank 3 excavation (based on results from MW-1 in January, 1992) Soil gas sampling in this vicinity also indicated the presence of TPH and low levels of toluene, ethylbenzene, and xylenes 52 Groundwater 5 2 1 Extent of Contamination Table 3 summarizes the analytical results for groundwater samples collected from the five monitoring wells at the Site The most recent data is depicted on Figure 8 As is illustrated by Figure 8, there are currently no contaminants at levels of concern in the Site groundwater Historically, the only compound detected at concentrations above the state MCL has been benzene, which was detected in two out of 14 sampling events from MW-1, in 5 of 12 sampling events from MW-2, and from 1 of 8 sampling events from MW-5 Benzene has never been • detected in MW-3 or MW-5 C 1MyFiles\AnnelwpwmlprojectslunionlClosureRpt wpd 9