My bet is that plans are to bring in multiple porta-potties. Also probably on the way are crates of MRE's or other methods of food. Someone on the ball should have been going around the city collecting leftover food from restaurants which are closed or going to close. Hopefully, there are dozens of large generators on the way, as well to keep at least minimal lights on and maybe run the fans.
It would be foolish not to plan for those folks in the Superdome to be there for 2 days or more. That means some means for minimal power production, lots of food, drinking water and of course, scads of extra potties. Flush toilets are going to be useless once there's flooding.
Well hopefully FEMA is doing the planning, NO mayor certainly doesn't appear to have done it.
If they bring in MRE's...they won't need porta-potties.