What the heck do you fill a hole that size with????
And, Where did it all go???
From the pictures that's a cylinder of earth at *least* 50' in diameter and 100+' tall. That is a *lot* of dirt to just vanish. There must have been a huge cavern down there that would put even the Government Warehouse in
Raiders of the Lost Arc to shame. I wonder how many more such caverns are ready to swallow up that much material?