On Thu, Aug 24, 2006 at 10:46:20AM -0400, Martin K wrote:
> 6 hours later and I'm still reading about the labyrinth of tunnels in 
> the St. Paul area! It takes a different kind of person than I to 
> deliberately try to get into abandoned tunnels in the middle of the night.

I'll say, let alone nearly get killed venturing into oxygen deficient
stagnant unused sewer pipes. As a (pseudo)engineer I would have totally
rigged up some ventilation first!

More seriously I've always wondered how well sealed those types of
underground areas are. Essentially, would a party of explorers in
disused tunnel eventually deplete the available oxygen? Is there enough
permeability to allow CO2 to dissipate into the ground?

I've never heard it to be a problem with deep caves and at least high
levels of CO2, unlike methane, produce an obvious choking feeling. But
makes you wonder why this sort of problem hasn't come up.

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