Duke Energy Corp. is seeking the dismissal of a $25.1 million judgment for groundwater violations related to coal-ash pits near a Wilmington, N.C., power plant.

The utility giant said in a news release that the fine by North Carolina environmental regulators was unnecessary and excessive, citing actions already taken by Duke, among other things, and disputing the state regulators’ methods for setting the fine. Duke has filed an appeal with the North Carolina Office of Administrative Hearings.

Duke in February agreed to settle charges that it violated the federal Clean Water Act by spilling coal ash into the Dan River in North Carolina last year, and said it would pay $102.2 million in penalties and restitution. The deal with federal investigators includes a five-year probationary period with a court-appointed monitor to ensure compliance with provisions of the agreement.

The Dan River spill focused national attention on the legacy problem of coal incineration near rivers. Duke is still working with state officials to fix problems at coal-waste sites and has said it potentially could spend more than $3 billion in coming years to shore up waste storage.

The company has estimated it has about 150 million tons of coal waste stored in 4,500 acres of ash dumps in the half dozen states where it has coal power plants, with about 70% of the waste in North Carolina.