McClellan environmental cleanup landmark comes down Published May 3, 2013 By Air Force Civil Engineer Center Public Affairs FORMER MCCLELLAN AIR FORCE BASE, Calif. -- A big white tent, an icon of the McClellan cleanup program, was removed recently, testimony to the progress of the Superfund cleanup at the former Air Force base in Sacramento, Calif. The mammoth tent was set up in 2001 to keep wind and rain out of a landfill, known as Confirmed Site 10, while it was being excavated. When the excavation halted in 2003, the tent remained over the 2-acre site to keep rainwater out of the 32-foot deep pit while the Air Force and regulators worked to determine a final cleanup remedy for it and 10 other sites. When McClellan was an active Air Force base, the landfill received a variety of industrial waste, including radiological waste from former radium painting operations. In 2012, the Air Force and regulators signed the Focused Strategic Sites Record of Decision which specified the remedy for CS 10 and the 10 other large former landfills and disposal pits at McClellan. The centerpiece of that protective remedy is the construction of an engineered consolidation unit, or CU, at the site of CS 10. The pit will be expanded, and a leachate collection system and two layers of liners will be installed before accepting soils. When constructed, the tent on the west side of the former base was the largest free-standing tent in the world. At 630 feet long, 204 feet wide and 66 feet high, it was both longer and wider than the California Capitol Building. Comprised of 31 arches, the tent was held in place with 5-foot anchors and withstood winds in excess of 78 mph. "Demolishing the tent is an exciting milestone in the cleanup at McClellan. It's a visible indicator of the progress that we are making." said Steve Mayer, Air Force remediation program manager for McClellan. "We've cleared the site and are moving forward with the CU, which should be open and accepting soils by September." The consolidation unit is scheduled to remain open through 2018 to accept soils from other McClellan sites before the final protective cap is installed. Follow-up, long-term monitoring and maintenance will be required.