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i <br /> ARCO #2133 Page 2 <br /> 1) The results of the April 1987 WEGE Soil Vapor Study indicated soil <br /> contamination throughout the site. <br /> 2) The results of the May 1987 Brown and Caldwell Soil Investigation <br /> indicated soil contamination throughout the site. <br /> 3) The 1969 installation of a sewage disposal system and the leach lines south <br /> of the property included the neighboring parcel, which at the time of <br /> installation was owned by the same individual. Septic systems are conduits <br /> which facilitate contamination migration and this possible migratory <br /> pathway should be properly investigated. <br /> 4) Lithological features of the site indicate shallow silty clay layers bounded by <br /> sandy lenses which facilitate the migration of contamination throughout the <br /> site. <br /> 5) The results of the September 1991 excavation sampling, prior to the <br /> installation of the waste oil tank, provided additional information that <br /> further indicated the extent of soil contamination. <br /> 6) The results of the September 1991 free product holding tank removal <br /> sampling provided additional information that further indicated the extent <br /> of soil contamination. ` <br /> 7) Depth to water data indicated that when monitoring wells E-1 through E-12 <br /> were installed in May 1984 groundwater was encountered between 14 - 26 <br /> feet below ground surface (BGS). Groundwater is currently being <br /> encountered at approximately 20 feet BGS. The definition of the plume of <br /> groundwater contamination was never identified south of the site, at 1984 <br /> water levels. Hydrocarbon contaminants generally float on top of the water <br /> spreading the contamination horizontally. The contaminants also move <br /> vertically, with corresponding fluctuations in the water table. The location <br /> and designation of the capillary fringe has changed, since the unauthorized <br /> leak, primarily due to the local effects of the groundwater extraction system <br /> and the regional drought. <br /> 8) Soil samples were collected during the May 1984 installation of monitoring <br /> wells E-1 through E-12, but were not laboratory analyzed. The drilling logs <br /> qualitatively indicated the presence of petroleum contamination. <br />