I do have devices that can read tape written 20 years ago. 8-track was from the 60's and 70's by the way, making it a bit more than 20 years.
First CDs came out in early 1980's. That's 30 years and the drives are still backwards compatible -- I can still put in my old Pink Floyd CD into my Blue-ray drive and the computer will play it. There is no reason to believe that won't continue for another 10 years or so as music is still being released on CD in commercial quantities. Despite the hype optical disks are far from dead.
Archival quality optical disks have a good chance of continued support because there is a substantial effort being put into them in the background by people like the National Archive, Library of Congress, and others looking for means to maintain long term records storage. It's not guaranteed that they will be around in 100 years. Maintaining any system that long is difficult, even simple paper. It's got as good a shot as any though.
An industrial site or process is generally the result of experimentation carried out in a lab. That means shit in the lab sometimes goes wrong.
They're making a comparison between university labs and commercial labs.
You're talking about students. They're not veteran technicians. Of course they don't know how to solder. And based on my experience with university engineering labs, it was learn by doing -- there was no "training". As a 20+ year veteran of electronics technician and engineering jobs, I can tell you some employers assume you know what you're doing, and some run IPC training programs (if you don't know what that is, then you probably don't know how to solder properly. One site took it to another level because they categorized soldering as "hot work", requiring additional training for fire safety and carrying extra safety regulation.
I think the premise of the article is probably correct.
So.... Just so I'm following. You want to build an air-tight container, then burn the rubble with gasoline inside the container... Oxygen? Combustion gas (radioactive combustion gas)? any consideration for these given?
and as to your hole... water table? Fault lines?