The EPA says Thursday that the deal also calls for reductions in air pollution from refineries in four other states outside Michigan.
Marathon will spend about $6 million to shut down a flare at the Detroit refinery's fence line. Marathon says Thursday that it will build piping to safely shut down the flare. Flares are mechanical devices -- ordinarily elevated -- that are used to combust waste gases.
The company also will spend $36 million to install systems that capture and recycle gases that otherwise would be sent to flares.
Marathon will spend another $283 million at facilities in Illinois, Kentucky, Louisiana and Ohio.