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FIRESTONE Service Center 400 North El Dorado Street, Stockton, California <br /> October 6, 1993 Site Assessment Work Plan-2072 01 Page 1 of 7 <br /> 1.0 PROJECT SUMMARY <br /> The site is located at 400 North El Dorado Street in Stockton, California and is currently non- <br /> operational. The facility provided automobile maintenance and repair services Site Vicinity and <br /> Site Diagrams are attached (Figures 1 and 2) <br /> On April 25, 1991, Ryan-Murphy, Incorporated supervised the removal of twelve underground <br /> storage tanks (USTs) and appurtenant piping from the facility. The tanks were believed to <br />' contain, at one time, leaded gasoline and used motor oil Laboratory analyses of soil samples <br /> collected from the UST excavations satisfied regulatory compliance objectives at all locations <br /> with the exception of the area surrounding tanks 4 and 5 Soil samples in this area contained <br /> hydrocarbon concentrations above state regulatory action levels <br /> Based on these laboratory findings, Ryan-Murphy returned to the site on September 10, 1991, <br /> and installed two soil borings adjacent (north-south) to the pit formerly containing USTs 4 and <br /> 5 (Figure 2). Laboratory analyses of the soil boring samples were mostly nondetect The low <br /> concentrations of gasoline and diesel observed were well below state action levels <br /> In response to the absence of contamination in the soil bonngs, overexcavation was performed <br /> on November 12, 1991, in an attempt to remove what appeared to be a relatively small volume <br /> of impacted soil Overexcavation was limited due to surrounding physical restrictions <br /> Verification soil samples collected following overexcavation activity contained petroleum <br /> hydrocarbon concentrations exceeding applicable California action levels Since these results <br /> exceeded state action levels, and the severe limitations inhibited further excavation, Ryan- <br /> Murphy proposes to further delineate the vertical and lateral extent of soil contamination <br /> surrounding the former UST pit, and to perform a short-term soil vapor extraction pilot study <br /> The followingwork plan outlines the strategies, methods and materials that will be used in <br /> P g � , <br /> conducting this project Information obtained through implementation of this work plan will be <br /> used to evaluate and develop remedial options and additional work plans as necessary <br /> 1 <br /> RYAN-hRfl PHY, INCORPORATFA Denver <br /> EmkomwNd l Construction mmagemeffit Lm Angeles <br />