A Duke Energy Corp. coal ash landfill that was damaged by Tropical Storm Florence has suffered further damage, federal officials said Sept. 17.

The spill occurred at Duke’s Sutton Power Plant site near Wilmington, N.C., when a portion of the landfill eroded, much like a similar incident that occurred Sept. 15 at the same plant, said Reggie Cheatham, the Environmental Protection Agency’s, director of the Office of Emergency Management.

It was unknown how much of the toxic substance...