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PROJECT BACKGROUND <br /> In 1988, Mobil Oil Co oration abandoned the former bulk <br /> storage and distributiorpn plant. All structures were removed <br /> from the property including one underground gasoline tank and <br /> four aboveground diesel fuel storage tanks. <br /> In August 1988, following removal of the underground gasoline <br /> storage tank, Kaprealian Engineering, Incorporated (KEI) <br /> collected and analyzed one ground water and two soil samples <br /> for fuel hydrocarbon constituents. Detectable concentrations <br /> of TPH and BTEX were present in the samples collected. <br /> On November 21, 1988, KEI supervised the drilling of six <br /> onsite exploratory borings to depths ranging from 12 to <br /> 13 feet below grade (fbg) . Analyses of soil samples <br /> collected from depths of 5 and 10 feet showed detectable <br /> concentrations of TPH-D up to 2,900 parts per million (ppm) <br /> and TPH-G up to 360 ppm. Ground water was encountered <br /> between 11 and 12 fbg. <br /> In February 1989, additional soil samples were collected at <br /> the site by KEI from 12 test holes at depths of 5 and 10 fbg <br /> using a backhoe. Analyses of soil samples detected <br /> concentrations of TPH-D up to 3, 600 ppm and TPH-G up to <br /> 170 ppm. Results of the investigative work revealed the <br /> presence of diesel-range contamination in the subsurface soil <br /> extending to a depth of 10 feet below grade and encompassing <br /> an area of approximately 3,700 cubic feet. Soil analytical <br /> data from test holes suggests that gasoline-range hydrocarbon <br /> contamination was limited to the northern portion of the <br /> site. <br /> In February 1990, Mobil Oil Corporation contracted Alton <br /> Geoscience to profile the soil in situ for potential offsite <br /> disposal. The results of the soil profiling were used during <br /> excavation as an aid in segregating the soil for disposal at <br /> appropriate offsite facilities. <br /> On July 9, 1990, soil excavation was initiated. Balch <br /> Petroleum, Inc. of Milpitas, California was contracted by <br /> Mobil Oil to perform the excavation under the supervision of <br /> Alton Geoscience personnel. Based on the results of the <br /> in situ soil characterization, approximately 6, 100 cubic <br /> yards of soil were excavated and properly disposed of at <br /> either the Class II facility of Liquid Waste Management, Inc. <br /> or at the Class III Durham Road Landfill. On July 23, 1990, <br /> approximately 7, 300 cubic yards of imported clean fill was <br /> used to backfill the open excavation. <br /> 1 <br />