In December 2005, a 700-foot section of the dam surrounding the Taum Sauk upper reservoir failed and released 1.4 billion gallons of water down Proffit Mountain and into Johnson's Shut-Ins State Park in Annapolis, Mo. About 6 million tons of rock from the original dam became aggregate for the newly designed roller-compacted concrete (RCC) dam, resulting in minimal waste and eliminating the need to haul any materials from the site. Five batch plants, four producing the RCC mix, ran simultaneously, and averaged 10,000 to 12,000 yards of concrete a day. Eventually, 2.8 million cubic yards of RCC, 160,000 tons of fly ash, and 300,000 cubic yards of conventional concrete were used to rebuild the dam.

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