Draglines are probably the cheapest way to remove overburden from coal seams but they sure can do damage unless top soil and the upper clay is stripped and stockpiled to be used in reclamation.
This has been the law of the land since 1978. I happen to know this law backwards and forwards.
What little I know about mining I learned at the School of Mines, Fairbanks. The best part of the course was the field trip where we got to drill a rock face way back in the zinc mine and blow it up with dynamite. There was an amount of stupid behavior with the detonation and explosive handling which shows that:
education is not a cure for stupidity.
--Kant, Critique of Pure Reason, 1787