Unfortunately you'll probably be fighting an uphill battle if it is coming through the floor (if you don't have a vapor barrier under the concrete). You should be able to tell if it is coming through the floor by putting a 2ftx2ft piece of plastic for a day and see if it is wet underneath.
Yeah, I know how that goes. Hopefully nature doesn't reclaim them too quickly - from the pics I saw, the one closest to the garage doesn't look too bad yet.
What a great thread! Thanks for posting all the pics - it is fascinating to go through. Sorry if I missed it, but what is the story behind the mustang (?) behind the building? Looks like it has been there for quite a while!