In this Feb. 17, 2010, file photo, the W.R. Grace mine is shown, outside of Libby, Mont. Libby, the town of 3,000 along the Kootenai River has emerged as the deadliest Superfund site in the nation's history. At least 400 people have been killed so far from W.R. Grace mine workers and family members who breathed in the dust they brought home in their clothes, to kids who played in waste tailings by the community baseball field. A cleanup proposal for a Montana town where thousands have been sickened by asbestos exposure calls for leaving some of the dangerous material in place rather than removing it. (AP Photo/Rick Bowmer, File)