Washington Post: In less than a month, the question of how to dispose of coal-combustion waste has gone from a largely ignored issue to a pressing national environmental concern that has sparked legislative proposals and the prospect of new regulation. Since the Dec. 22 coal-ash spill at the Tennessee Valley Authority’s (TVA) Kingston Fossil Plant, which poured a billion gallons of toxic material over 300 acres, lawmakers and regulators have said the federal government should revisit an issue it has …