NASHVILLE (AP) — State environmental regulators say it shouldn't cost ratepayers more money or take as long as estimated for the nation's largest public utility to complete a massive, court-ordered coal ash cleanup at a Tennessee power plant.

They also say it's possible the Tennessee Valley Authority could save money by following the order to excavate and move the ash at Gallatin Fossil Plant. They say leaving the 11 million cubic yards (8 million cubic meters) of ash in unlined pits and capping it could fail to stop pollution and require future cleanup.

The Tennessee regulators' skepticism over the utility's 24-year timeline and cost claims is detailed in court filings and state records.

The utility says it's taking steps to follow the court's cleanup requirement, even as it appeals the order.