It's interesting how the mines work, all of the coal is taken:

https://en.wikipedia.org/wiki/Longwall_mining

https://www.youtube.com/watch?v=kXQwdQnT60k

https://www.youtube.com/watch?v=WmwEB4DY_jc

But aside for the CO2, the coal ash is a big problem:

https://www.youtube.com/watch?v=hvx-W-XAie0

As are the mine fires:

https://en.wikipedia.org/wiki/Coal-seam_fire