AFB and Screened Bottom Board - Safe for a New Colony?

If you read my post about using sulfur to kill a colony, you know I had my first encounter with AFB this week. The colony was on a screened bottom board, sitting on a double stand.

The bottom board was pretty old, so I decided to burn it along with the frames rather than being penny wise and pound foolish. I also burned the migratory cover. While the frames, cover, and BB were burning I scorched the inside of the three medium supers the colony was in.

Now my question... Given that the hive was wide open on the bottom, what is everyone's thought about the safety of placing a new screened BB colony on the old stand? I'm thinking there are probably AFB spores all over the place on and under the stand in that spot. I could scorch it, but what about the ground underneath? I'd appreciate most hearing about others' actual experience in similar situations.

Thanks!

-Pete