This kind of reclamation only works for high, high dollar projects. They did a whole lot more than separate the  waste concrete chunks that were buried in the spoil piles. They dug out the trees and roots and ground them for mulch. They dug up the concrete and ground it up to be used as kind of a gravel paving. Then they hauled in dirt, some of it from a long ways away because it was an old mine after all and a lot of the material had been hauled away. Then, remember that it was a swamp and swamp land tends to settle. It is very expensive to geo-pier ground and do continuous flight drilling and pile install but that also had to be done. It was a hugely expensive operation but the whole area will benefit but still we have guys complaining about the ecological bad effects because they don't realize what a disaster it was before Tesla bought it for way too much money and put in a factory.
Strip mine sites are largely avoided here also. I guess part of it may be due to the mining companies fear of liability. Near Colstrip, the mines paid contractors to cut and bale the hay and then just gave the hay away to locals because of their fear of liability. What do you want to bet that local hay producers howled because they couldn't sell their hay, so it ends up being a huge no-win deal for the mines.