Probably water. ;) Maybe for fire-fighting? Seems a little close for that though, if something went wrong it could be in the middle of it. I can't think of a

Probably water. ;) Maybe for fire-fighting? Seems a little close for that though, if something went wrong it could be in the middle of it. I can't think of anything else though. Edit: Maybe it feeds some sort of un-manned fire suppression system? That would be pretty smart.