Some 450 construction workers are converging on a site in Pardeeville, Wis., to convert the state's largest source of sulfur dioxide (SO2) and mercury pollution into a poster child for cleaner, greener emissions. Peak periods will push the number of workers on site past 600 as crews assemble an air-quality control system and the facilities required to house it at Columbia Energy Center, a coal-fired electrical station undergoing $627 million in upgrades, including construction of SO2 and mercury-reduction systems. Related Links: ADM Moves to Advance Carbon Storage Efforts Power Company Goes Lean to Build Clean "There isn't time to complete