what's the meaning of healed coalfield in this sentence?

Coalfields left a mess on the landscape. I live in a former coal community and there was always dirt around with slag heaps and lorry loads of coal going past all the time. Once the pits closed all the grime went and all that was left of the pits were scars where they once stood. These are the healed areas.

I would take that to mean the coalfield had returned to it's original pristine condition,with vegetation growing where once bare ragged landscape existed.