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EXCAVATION AND REMOVAL OPERATIONS <br /> ' TANK REMOVAL <br /> iTanks T-1 through T-3 were purged of remaining product before tank excavation and <br /> ' removal operations Dry ice was introduced into the tanks at a ratio of at least 15 pounds <br /> of dry ice for every 1,000 gallons of tank capacity The dry ice was allowed to sublimate <br /> ' and displace the atmosphere in each tank. An LEL meter was used to measure the <br /> concentration of volatile vapors emanating from each tank's vent Once the LEL reached <br /> ' 10%, the tank was removed from the excavation <br /> ' Following purging, a backhoe was used to excavate around the flanks of each tank. The <br /> tanks were then removed with a 20-ton crane. Upon removal of each tank, a visual <br /> inspection was conducted to determine the structural integrity of each tank. Tanks T-1 <br /> and T-2 were actually railroad tanker cars composed of heavy gauge steel No holes or <br /> cracks were observed in tanks T-1 and T-2. Small holes were observed in tank T-3 <br /> Excavation 3 feet into native soil below each tank occurred before soil g <br /> sam lin The <br /> sampling <br /> depth of the excavation containing the tank cluster T-1 and T-2 varied from 110 to <br /> 12.0 feet below ground surface The excavation containing tank T-3 was approximately <br /> ' 15 feet in depth Inspection of the base and sidewalls of the tank cluster showed no visual <br /> signs of staining Inspection of the excavation containing tank T-3 showed visual soil <br /> ' contamination at the fill pipe end of the tank <br /> ' Excavated soil was stockpiled and covered with Visqueen The excavations were <br /> barricaded appropriately until backfilling with clean soil is authorized by San Joaquin <br /> ' County Local Health District. <br /> The excavated tanks were transported to Enckson's, Inc , located in Richmond, California, <br /> under Hazardous Waste Manifests. The Hazardous Waste Manifests, San Joaquin County <br /> Page 5 <br />