As much as we whined about the Feds inspecting us twice per year minimum, they really were looking out for us. Some things we thought were petty and harmless could still keep ya from going home to see the family at the end of shift.
They are pretty sticky in that mine. Safety is a big thing there.
That being said, part of it is under a lake. During some test hole drilling,they drilled up into the lake. It started draining. They bonded an open valve into the hole, then closed the valve. That portion of the mine has been backfilled since then.