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indication of contamination. Samples were extracted using a tube sampler with 1.5" stainless steel <br /> sample tubes. Each end of sample tube was covered with Teflon sheets and a plastic sample tube cap. <br /> Samples were kept on ice and transported under chain of custody to the on site laboratory. All push <br /> bores were logged for soil texture classification and any other visible characteristics(See recap sheet <br /> for soil classification). <br /> Sample Analysis <br /> All push bore samples were analyzed by GC/MS EPA Method 8260 in a mobile laboratory located <br /> on the site. Samples taken by hand from the excavator bucket from under tank #3 and the north <br /> excavation wall on August 21, 1998 were delivered to Onsite's laboratory in Fremont, California <br /> (Results of re-sample analysis are located on the recap sheet attached). These four samples were <br /> analyzed by EPA Method 8260. <br /> Findings <br /> All push bore samples taken on August 10& 11, 1998 were found to be below the detection limit for <br /> all compounds analyzed. On August 21, 1998 the soil under tank#3 was re-sampled at a depth of 21 <br /> feet. This sample was analyzed for TPHg with results of 120 mg/Kg, which is a major reduction from <br /> 4400 mg/Kg for TPHg of the original tank sample. This re-sample was non-detect for MTBE. A re- <br /> sample of the north wall was taken 7 feet below the original tank pull sample. It was analyzed at 3.6 <br /> mg/Kg for TPHg with non-detect for MTBt. <br /> CONCLUSION <br /> Pipeline Area Contamination <br /> Push bore samples taken directly below pipeline, P-24', P-44', and P-7-6' were analyzed at non- <br /> detect for all compounds. The contamination shown on these pipeline samples must have resulted <br /> from a very small spill of short duration that did not penetrate to lower depths. These spills did not <br /> contaminate soils below eight feet in depth and will not place the underground water supply in <br /> danger. <br /> Fuel Tank Area Contamination <br /> The amount of contamination of the soil under the south end of tank#3 was shown to be in inverse <br /> proportion to the depth of the sample. The sample at 14 feet of depth was 4400 mg/Kg for TPHg, <br /> while the sample at 21 feet was 120 mg/Kg, a reduction ratio of 36 to 1. The soil classification for <br /> the sample taken at 21 feet is a silty sand. The soil classification in PB#4 starting at 28 feet is a dense <br /> silt proceeding to a sandy silt hardpan at 31 feet. The low,permeability of the soil directly under the <br /> 21 foot sample will prevent any contamination of the water table. None of the samples in PB#4, <br /> located six feet south of tank#3, showed any evidence of contamination. Lateral movement of the <br /> spill was confined to tank expavation. The tanks may have been backfilled with higher permeability <br /> soil than the surrounding area. A sample taken eight feet to the east of re-sample TK#3@21' showed <br /> levels of TPHg at only 24 mg/Kg, which is below normal action levels. This indicates that lateral <br /> movement of the contamination was low. At the time these tanks were removed, the daily inventory <br /> did not show a loss of gasoline from any of the tanks. <br /> North wall contamination area was re-sampled at 11 feet, which is 7 feet below the original sample <br /> (N-SIDE WALL @ 4'). TPHg for this re-sample was 10%of the original sample. A low permeability <br /> layer of hardpan was found at a depth of 26.5 feet in PB#5, which is located 10 feet to the northwest <br /> 2 <br />