Suncor Energy continues to clean up contaminated water and land near its Commerce City oil refinery north of Denver.  The company met Thursday's deadline to clean up the banks of the creek early.   Last November authorities discovered a petroleum-like substance containing the carcinogen benzene leaking into the groundwater near Sand Creek where it meets the South Platte River.  The Colorado Department of Public Health and Environment is overseeing the cleanup.  Spokesman Warren Smith talked with Colorado Public Radio’s Anna Panoka.