Stock Photo: Commerce City, Colorado - A cleanup worker removes a tar-like substance from behind containment booms on Sand Creek near the South Platte River at the Suncor Energy refinery Cancer-causing benzene is leaking into the water at levels as much as 100 times. Commerce City, Colorado - A cleanup worker removes a tar-like substance from behind containment booms on Sand Creek near the South Platte River at the Suncor Energy refinery Cancer-causing benzene is leaking into the water at levels as much as