The Environmental Protection Agency Tuesday announced it will investigate a project to expand a massive BP refinery in northwest Indiana. The Bush-era EPA signed off on the plan in the last hours of the administration. Critics say the project would allow BP site, already one of the largest polluters in the Chicago area, to avoid stringent pollution requirements under the federal Clean Air Act. The current EPA has cracked down on polluters in the past few months, slamming BP for violating laws on benzene, a nasty chemical linked to leukemia.