The U.S. Environmental Protection Agency is due to issue long-anticipated regulations on Friday for the disposal of coal ash, a byproduct of coal-based power production that contains toxic materials such as arsenic and lead.

 

The agency, which agreed to the Friday deadline to settle a lawsuit filed by environmental groups, first proposed rules governing coal ash storage in 2010. That was in the wake of a massive spill at a ruptured holding pond in Tennessee that has cost more than $1 billion to clean up.

 

Environmental groups say the practice of storing coal ash in holding ponds supported by permeable, earthen dikes leads both to contamination of surrounding groundwater and the risk of catastrophe when those dikes fail, as happened in Tennessee and at a site in North Carolina earlier this year.

 

The EPA has said contaminants such as arsenic, mercury and cadmium in coal ash could cause cancer if they get into the water supply.

 

The agency has put forward two proposed sets of rules, the more aggressive of which would classify coal ash as hazardous waste, over which the agency would have direct oversight. The alternative would label it non-hazardous, with states acting as the primary regulators.

 

Both environmental groups and industry backers say it is unlikely that the EPA, after years of review, will label coal ash as hazardous waste.

 

Less clear, environmentalists say, is whether the agency will require the dismantling of existing holding ponds, and the transfer of the waste to dry-storage landfills or for re-use in products like concrete and drywall.

 

The new rules will likely require monitoring of coal ash disposal sites, as is already the case in some states, and will likely stop more coal ash from being dumped into new or existing holding ponds.

 

An EPA spokeswoman declined to comment on the pending regulations ahead of their release.