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1 <br /> TreadweINWIo <br /> ' Island Site All backfilling and compaction activities were observed by Kleinfelder & <br /> Associates, Inc , the project geotechnical engineer <br /> 6.0 CONCLUSIONS AND RECOMMENDATIONS <br /> The soil proposed for excavation in the 12 April 2004 workplan for the Site has been excavated <br /> and characterized and sent off-site for disposal Additionally, the former excavation areas were <br /> backfilled with clean imported soil The soil and groundwater samples collected at the bottom of <br /> the excavation indicate that remediation,confirmation, and soil disposal activities were <br /> conducted at the Site between 10 June and 16 June 2004 according to the approved remedial <br /> workplan <br /> The source of the soil and groundwater contamination identified at the northern edge of the <br /> property appears to have been the result of releases at the former gasoline service station at the <br /> Site The source of this identified groundwater contamination appears to have been removed <br /> during the recent remedial activities We base this conclusion on the following <br /> rI Three previously unidentified USTs have been removed from the sidewalk adjacent to <br /> the Site, and soil below the USTs have been excavated to a depth of 25 feet <br /> (approximately six feet below the groundwater table) These USTs were directly above <br /> ' the area with the highest soil and groundwater contamination <br /> ' 2 Investigations conducted around the pipelines and former pump island associated with <br /> the UST identified shallow soil contamination Soil in the area of the former pump <br /> islands was excavated to below detection limits except for one sidewall sample with <br /> relatively low petroleum hydrocarbon concentrations and one bottom sample at the <br /> ' groundwater interface All significant soil contamination above the groundwater table <br /> on the Site has been excavated <br /> Residual groundwater and saturated soil contamination exist at the northwestern area of the Site <br /> • and, due to the groundwater flow direction, likely extend off-site in a northeasterly direction into <br /> 1 <br /> 1 25971020 DGD 10 23 August 2004 <br />