W.R. Grace & Co. has agreed to reimburse the federal government $250 million for investigation and cleanup of asbestos contamination blamed for sickening hundreds of people, some fatally, in the northwestern Montana town of Libby.Approval of a federal bankruptcy judge is necessary to cement the agreement announced Tuesday by the U.S. Justice Department, which said $250 million is a record sum for reimbursement through the government's Superfund program of environmental cleanup. Taxpayers have been footing the bill for the U.S. Environmental Protection Agency's Libby investigative work and cleanup. The agency arrived in Libby in 1999. Expenses total $168 million and another $175 million in costs are likely, said Paul Peronard, EPA's Libby project leader.