MONCKS CORNER, S.C. (AP) — For months, two South Carolina electricity providers have been working to remove millions of tons of coal ash from waste pits.

But just across the state line in North Carolina, top officials say this very type of ash-removal operation in South Carolina and other states could be dangerous. The worry in North Carolina comes after Duke Energy’s massive coal ash spill coated 70 miles of the Dan River in toxic sludge.