A large government-funded electric utility said a court-ordered clean up of a coal waste site will take about 24 years to fulfill, and that the utility is considering appealing the federal court's mandate within the next 30 days.

The Tennessee Valley Authority said there is an early October deadline to decide if it will appeal, an action that would stall the clean up schedule at the coal plant.

The utility's 24-year cleanup estimate included a half-a-billion dollar plan to build a fully-lined landfill to dump the coal ash waste. A second option would cost the utility $2 billion.

A federal judge ordered TVA to modify the current waste storage dump at the plant last month. The judge ruled that pollutants leaking from the site into the Cumberland River violated the Environmental Protection Agency's Clean Water Act regulations.