The acid waste is nothing bad...
I wouldn't try to get in there, as the room is alarmed. The guy who had to fix a projector during class set off the alarm and it was quite annoying.
The next time you walk over a metal grate on campus, look down, and you might be surprised at what you see.
I can also confirm that there is a tunnel entrance in the new North end zone of DKR, as you could clearly see it during construction. I wouldn't be surprised if there is another entrance somewhere under the West side of the stadium, but I haven't looked.
As far as water goes, I'm sure they have bilge pumps that pump water out into waller creek or a sewer system.
It'd be cool to explore them, but it's definitely not worth being expelled.