Rubber membrane liner confines low level radioactive material

One of the most sophisticated membrane lining projects in the world was undertaken in 1979 by the Cotter Corporation, Canon City, Colorado, producers of vanadium and uranium, when a new tailings pond was built to handle mill tailings and effluents. To comply with local, state and federal regulations, Cotter sought maximum protection for downstream residents. The lining was designed to keep leakage near zero and withstand tailings and water pressure at the deepest part of the pond. Other considerations were compatibility with alkalis and acids and durability and effectiveness of the lining beyond the life of the mill. ''We had to be sure the impoundment would outlast the mill because of the need for long-term isolation of the tailings,'' said Joseph McCluskey, Cotter's executive vice presient. Gotter chose an industrial grade sheeting made of Hypalon synthetic rubber, a chlorosulfonated polyethylene, that has an exposed life expectancy of 40 years; however, once covered with earth and tailings, it will last much longer. The sheeting consists of a reinforced scrim sandwiched between two sheets of Hypalon. The rubber comprises nearly 50 percent of the total linear weight, and the reinforcement is a 10' x 10' 1000D polyester scrim whose open weave allows the rubber to penetrate the fabric and create excellent adhesion between the layers. After two years, the impoundment contains approximately 1400 acre feet of liquid. Currently, about one half of the pond consists of run-off with tailings and liquids from the new mill making up the difference