From the Detroit Free Press: Marathon refinery gets OK to expand, but concerns expressed
Part of the concerns were of course making sure there were jobs for Detroiters - which was given:
Marathon made concessions to improve pollution controls and help the nearby community, including promises of preferential treatment for Detroit residents.
There are some concerns about increased emissions, but its in an industrial area, the refinery capacity in the US is badly in need of expansion and Michigan and Detroit in particular is in drastic need of more jobs, which this expansion will provide.
Certainly well past time this was approved, and good luck to Marathon on the expansion.