Interestingly, in real life there are no salt mines in Upper Michigan, where the main Enrichment Center is located. There are plenty of other mines, though.

Maybe all of those old test chambers were vitrified in salt instead of just concrete, come to think of it...

There's a 14 mile underground submarine communications system in upper Michigan. Despite being hundreds of miles from the nearest ocean, it could contact submarines all over the planet: https://en.wikipedia.org/wiki/Project_Sanguine

At it's peak the system used ~3MW power plant to run the system.

Just a note that while there are[1] 3 transmission lines of 14, 14 and 28 miles in the UP, the lines themselves were mounted on (essentially) telephone poles. The end of each line does have 1 to 3 miles of buried horizontal ground wire though and an array of 100 to 300 foot deep bore holes.

[1] or at least were; the project was shutdown in 2004 and while the paths of the antenna lines still seem to be visible on satellite photos[2] it looks like the lines themselves may have been removed.

[2] The transmission station itself is at https://goo.gl/maps/q5BwduBqbBpAaf1L9 with the 28 mile antenna segment running roughly north south just to the west, one 14 mile segment running east-west a little to the north of the facility and the second to the south.

I played Portal 2 for the first time while working on my MS at Michigan Tech, in Houghton. It was a memorable moment to listen to that Cave Johnson audio log and then turn away from my monitor to look out the window at the nearby defunct copper mines.

The scientific applications are endless!

Zisss.. could eeeeesssssily be solved viss.... a komputer!