I was a State Police dispatcher in Detroit for 25 years.. This is the 2nd time in my memory this has happened.. First time shut down parts of the system for days.. Folks where yammering about how the freeways (We called them Ditches since they are dug down for sound control) were designed to drain into the river if it flooded (not at all true in case anyone is wondering, that was NOT a design consideration and it is NOT how it works when this happens).
The problem is a combination of two or sometimes 3 things
Trash blocks the drain grates This is due to littering, and "Blow off" from trucks (Epically garbage haulers) and such preventing proper draining.
And in a really super soaker of a storm the pump houses . Just can not pump fast enough.
Add to that some folks will dump "Hardware" into a pump pit, and break the pumps. (The optional 3rd cause) and you have a flood.
Last time one of my Sgt's took a copter ride over the city with Pat Monk.... Who did not have a passenger side door on his copter so the poor sgt was ... In the rain.
