Yeah the drain is maybe 1/2 inch higher, and think it's just sand (ex: the ground under the foundation) that's there, but I'll have to scoop it when it's dry, maybe it's just dirt on top of cement. Either way I'm thinking of cleaning it up and putting cement so it's level with the drain. This will be a very tedious process, don't want cement inside the drain.
I'd probably be best to take this project up in the winter when it's super dry in there and just cap it temporary until the cement is poured and dry, just to be on the safe side. A round piece of foam taped should probably do the trick then I can trowel the cement around it.
A humidity gauge is a good idea though, never thought of that. I also need to setup my dehumidifier so it drains through a hose instead of to a bucket. I have it on in there now and it runs maybe a couple hours then I need to empty it.