Bobby Joe- Thanks for the update. I think we get more news from you than from management.

By compressed air pipe, I presume you mean the large orange expandable (plastic? fabric?) tube we see connected to a fan. That would be the air supply to keep the tunnel ventilated. I assume they can take that in and out of the tunnel fairly easily, so I'm not surprised you wouldn't see it (or any other equipment that can be stored in the tunnel) on the weekend if that's what you meant. They would also have a more permanent hard pipe system to run compressed air into the tunnel to run equipment such as drills. Much easier and safer than using gas, propane, or even electrical equipment in the tunnel.