Test it by putting lots of water down the drain where it is. Like, turn on the hose.
The obvious point however, is that sumps don't work without electricity, so natural drainage is vastly superior.
I found out that you can get a 24 hour backup battery for a sump, but I won't be able to get it until after the storm. It looks like you need those professionally installed.
You also cannot buy flood insurance in the DC area right now