Have you ever gone along a Pa. back country Road perhaps past some old Strip Mining Land and you see just a single old bulldozer or Grader just sitting there abandoned but looks like its ready to go to work.
Like you see in the picture below
Well it was left behind by Mine Owners deliberately with the belief that as long as one piece of equipment remains on the property they still have control of property and State of Pa. DER can not force them to forfeit a Coal Reclamation Bond which can cost millions to post.
Which guarantees the mine property will be cleaned up.
One of the most famous of these is sitting along Pa 51 Near Uniontown Which unfortunately was destroyed and is tied up in a lawsuit.between new and old property owners
https://archive.triblive.com/news/suit-seeks-restoration-of-giant-steam-shovel-in-fayette-county/
Hopefully some one will restore it but belief leaving a piece of equipment proves property ownership to prevent forfeiting a reclamation Bond doe not when its time to go to court after a mine owner. But the practice which may of had some truth back in 50s still goes on.