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. ASSESSMENT HISTORY ,!I Initial UST Removal and Sampling Activities On April 21, 1993, two 10,000-gallon capacity, leaded gasoline underground storage tanks and one 5,000-gallon capacity, diesel underground storage tank (USTs) were removed from the subject site. Evax Technologies, Inc. inspected the tanks and collected soil samples from beneath the ends of each leaded gasoline UST, and one sample from beneath the fill end of the diesel UST immediately subsequent to removal. All samples were retrieved from the floor of the Id excavation at 13.5 feet samples bsg. Additionally, two soil les were collected from the soil Y p stockpile flanking the excavation. The stockpile was moved to the south end of the property ' prior to backfill of the excavation in May 1994. Analytical results of the soil samples revealed that elevated levels of Total Purgeable : l Hydrocarbons as gasoline (TPH-g) and total extractable petroleum hydrocarbons as diesel (TEPH-d), volatile aromatics benzene, toluene, ethylbenzene, xylenes (BTEX), and lead were present in the samples collected from the excavation and from the stockpile. The overexcavation of the former tank pit was initiated on July 16, 1993 by equipment operator Mark Burns and a W.W. Irwin, Inc. staff geologist as requested and contracted by the Pegasus Group. The work was periodically supervised by Mr. Michael Collins, SJCPHS-EHD Registered Environmental Health Specialist. As the excavation proceeded, soil samples were F - collected for lithologic analysis and organic vapor analysis (OVA) meter readings were taken = 1J ' in order to direct the excavation by determining the level of contamination and the direction of migration. The excavation was expanded slightly in all directions from the original tank pit to _ an area approximately 35 square feet and to a depth of approximately 18 to 20 feet below ' surface grade. The excavation was halted when the excavator reached the limits of its extension and the northern wall became inaccessible. Ground water was not encountered. - An estimated 260 cubic yards of newly-excavated soil was removed from the tank pit and stored at a location on the south side of the property, and separately from soil stockpiled during the tank removal operation. Upon completion of the excavation activities, two bottom- and four side-wall samples were gathered in the excavator bucket as directed by Mr. Collins. The soil samples were then retrieved from the bucket of the excavator by driving a clean hand-sampler containing a sterile, two-inch diameter, six-inch stainless steel tube into the gathered soil. The t. sample tube was immediately sealed with Teflon` tape, capped, taped, labeled, and placed on ice in a cooler for transport to a California Department of Health Services-certified laboratory for analysis. Appropriate chain-of-custody procedures were followed during sample handling. Each sample was analyzed for TPH-g by EPA Method 8015, BTEX analytes by EPA Method 8020, and organic lead per the California Leaking Underground Fuel Tank manual (State Water Resources Board, 1989). W.W. rnvin,Inc. Project No.33016,04 January 1995 2 I