Duke Energy says the move is an attempt to use "fear and the courts to upend public policy."

State environmental officials must approve Duke's disposal plans, which include testing the site's groundwater monitoring wells at least twice a year.

The company plans to cap storage basins in Cayuga, New Albany, Owensville and Terre Haute, Indiana.

As Indiana environmental regulators grapple with how to deal with the storage of coal ash at power generating stations, environmental groups push for tough standards.

A group of environmental and health advocates are especially concerned about Indiana's coal ash ponds and protecting federal legislation to clean them up.

The keynote speaker at Saturday's event will talk about the new federal coal ash rules, and how they may impact Indiana communities.