Duke Energy says it will publish federally mandated maps that it previously refused to publish, showing what could happen to neighboring properties if a coal-ash pit burst.
Two environmental advocacy groups had said last week they planned a lawsuit to force disclosure of the information withheld for more than a dozen Duke Energy sites in Indiana, Kentucky and North Carolina.
The groups said Duke Energy was the country's only electric utility not providing the dam safety information.
The Charlotte-based company said it's changing course after reviewing how other utilities complied with a two-year-old U.S. Environmental Protection Agency rule requiring the maps showing what could be covered by coal-ash in a disaster. Coal ash is the byproduct of burning coal to generate electricity. It can contain toxic heavy metals including lead, arsenic and mercury.
After the review of other utilities' responses, "we agree it is appropriate to post additional information and make it available to the public," Duke Energy Senior Vice President George Hamrick said in a statement.
Duke Energy was required to make public its emergency action plans for each of its coal ash storage sites with a significant risk of serious harm if retention walls failed, the advocacy groups Southern Environmental Law Center and Earthjustice said.
"It is a shame that citizens have to threaten to sue Duke Energy to get it to obey the law. The public should have had this emergency information for months," Southern Environmental Law Center attorney Frank Holleman said in a statement.
The 2015 EPA rules apply to new and existing coal-ash landfills or impoundments, and require electric companies to maintain a public website with access to compliance information.
The EPA's coal-ash rules, including emergency planning requirements for retention pits, were developed after a 2008 spill at the Tennessee Valley Authority power plant in Kingston, Tennessee. A containment dike burst and the resulting flood coated more than 300 acres and dumped waste into two nearby rivers.
Since then, the EPA documented coal ash waste sites tainting hundreds of waterways and underground aquifers in numerous states with heavy metals and other toxic contaminants.
Three years ago, a drainage pipe running below a waste dump collapsed at a Duke Energy plant in Eden, North Carolina. The estimated 39,000 tons of coal ash spewed into the Dan River and coated the waterway for more than 70 miles.