[DJlaysitup]

Underground isn't a viable engineering choice for parts of Texas and Oklahoma.

I realize that - but that's why I said that it would be expensive...if they could build submarines in WWI surely they can engineer an underground room in Oklahoma in 2013.

Difficult and expensive - yes...impossible - surely not.

[driftdiver]

Doesn’t need to be underground although that is desirable.

Solid concrete and anchored deep into the ground is sufficient. Concrete block is not strong enough.