Sure, Mike, but how do you protect against an airplane falling out of the sky?
Build the pop by blasting out a tunnel deep into a mountain and out again on the other side. Then a 90 degree shaft in the middle into the pop rom itself. (So, if somwone wan't to create a shockwave in the pop, they have to have two blasts, and it's hard to do rigt)
or having the building that houses your generators flattened by a runaway semi?
You have 2+2 generators, two in a backroom with it's own proper ventilation shaft, and one in each end of the tunnel that goes across the mountain. (You might concider Jet-turbines). Each generator has it's own fuel supply, and power wiring is redundant. The pop itself should be a -48V DC plant.
Or the ever present possibility that the building next door will have a gas leak and explode?
Explosions in the access tunnel is non fatal, and probably some gas- detectors and proper fans would be a good thing to have.
And what about that house-sized meteor that could come hurtling down?
Likely to shake the mountain, so, we build a house inside the cave, and put this house on suspenders (that will provide proper shock absortion). Airconditioning is a separate problem, usally the mountain leeks enough wather (+5 centigrades) that you can run through your heat-exchanger, or you have to drill for wather. If we have several of those locations, all with 24*7 staffin, I think it would be produce a good service, even when there are no customers left. --Peter Ps: Make sure that your external connections are redundant enough, microwave towers ontop are likely to be wiped out.. --::))