NASHVILLE, Tenn. — A federal utility is appealing a judge’s order to excavate and move its coal ash at a Tennessee power plant.

In Nashville federal court Monday, the Tennessee Valley Authority filed an appeal notice over its Gallatin Fossil Plant outside Nashville.

Spokesman Scott Brooks says TVA will comply with the order during appeal.

TVA says it would take 24 years and cost $550 million using a lined landfill onsite or up to $2 billion and possibly a different timeline if it’s offsite.

The Southern Environmental Law Center, representing one environmental group that sued, says TVA overestimated the numbers.

In August, the judge said coal ash storage is leaking pollutants into the Cumberland River and violating the Clean Water Act, but with scant evidence of concrete harm beyond risk and presence of pollutants.