I can't find the article in question now. It was on the bbc news website many years back IIRC. They got caught by security in the stadium who were very surprised that they got in!
it will be them old workings, there was some old infrastructure that existed after the commonwealth, but was sorted some years later after it became the council house, I'm fairly certain it was that, there was a big article at the time in the M.E.N
I'll keep trying to dig it up, it was something about two boys and the ashton canal. This one you are mentioning sounds interesting as well. Trying to find more about the storage tank mentioned here: