Sioux Energy Center

 Sioux Energy Center, a coal-fired power plant operated by Ameren Missouri, sits on the Mississippi River in St. Charles County. The EPA denied Ameren an extension to close a pit where it deposits byproducts from the coal scrubbers on the plant.

The move was part of a series of steps the agency said it would take to protect communities from harmful coal ash contamination.

Ameren Missouri must stop dumping waste from two of its coal-fired power plants into nearby pits following a federal crackdown on coal ash that denied the electric utility an extension to comply with new regulations. 

The move could force the utility to retire at least one of the facilities years ahead of schedule. 

The Environmental Protection Agency on Wednesday announced several steps to “hold facilities accountable for controlling and cleaning up the contamination created by decades of coal ash disposal.” Coal ash is created by the burning of coal at power plants and can contain toxic chemicals, including arsenic and mercury. 

For decades, coal ash has been stored by many utilities in pits near the plant, where it can leach into the groundwater and pollute waterways or even drinking water. Ameren has one remaining coal ash pit that has yet to be converted under new regulations. 

“I’ve seen firsthand how coal ash contamination can hurt people and communities,” EPA administrator Michael Regan said in a press release. “…For too long, communities already disproportionately impacted by high levels of pollution have been burdened by improper coal ash disposal.” 

In the release, the EPA announced it would act on utilities’ requests for deadline extensions to stop dumping coal ash at their facilities and then close them. It found four of the more than 50 deadline extension requests it received incomplete. Two of them were from Ameren Missouri — one for the Meramec Energy Center in St. Louis County and the other for the Sioux Energy Center in St. Charles County.

The EPA also plans to notify several facilities that it believes may be posing a risk to the public health and environment. It did not list the facilities. And the agency announced it would finalize a permitting program for coal ash disposal and existing ponds. 

The Sierra Club, a national environmental group, said in a release it was encouraged by EPA’s decision to enforce safeguards against coal ash contamination. 

“Ameren’s own monitoring has shown that the ash ponds at the Sioux plant have been leaking boron and sulfate into the groundwater at levels far exceeding state standards for years,” said Andy Knott, interim central region director for the organization’s Beyond Coal Campaign. “Ameren must do a better job taking care of our region’s air and water quality because that translates to a better quality of life.” 

The EPA issued a rule in 2020 requiring that utilities stop disposing of coal ash in unlined ponds by April 11, 2021. 

Ameren requested an extension to continue disposing of coal waste in its one remaining pond at Meramec until the end of this year and close the ponds by Oct. 17, 2023. Meramec itself is slated to close this year

It asked to keep open a lined pit for depositing gypsum, the byproduct of scrubbers meant to limit emissions at coal plants, at Sioux until October 2023.

In the case of Meramec, the EPA found Ameren failed to include a risk mitigation plan and enough groundwater sampling information. At Sioux, Ameren failed to convince EPA that it couldn’t feasibly close the gypsum stack any faster than it proposed. That proposal also lacked sufficient groundwater monitoring information. 

Brad Brown, a spokesperson for Ameren, said the company was reviewing the EPA proposal documents. 

EPA will take public comment and has proposed requiring that Ameren stop dumping disposing of waste at the Meramec ash pond and the Sioux gypsum stack within 135 days after the agency’s final determination. 

At Sioux, EPA noted it was likely the hastened deadline would force a temporary outage. Ameren, however, is required to meet certain energy generation standards to ensure the electrical grid remains reliable. 

The EPA said Ameren stated the coal-fired boiler at Sioux is needed for reliability purposes but the company “provided no information or evidence to support this statement.” 

The EPA proposed that if the regional grid Ameren belongs to — Midcontinent Independent System Operator — approves the temporary outage, environmental regulators will not grant Ameren an extension to close its coal ash pits. But if MISO does not, the EPA could grant a further extension. 

Environmentalists have also pushed Missouri regulators to require Ameren to get a permit for shuttered ash ponds at its Labadie Energy Center in Franklin County following a U.S. Supreme Court ruling governing groundwater pollution

That ruling, which came from a dispute in Hawaii, decided that entities discharging potential pollutants into groundwater must get a permit if the discharge is the “functional equivalent of a direct discharge from the point source into navigable waters.” 

In Ameren’s case, environmentalists argue, that means it needs permits to govern its coal ash ponds because the groundwater near the plant flows toward the Missouri River and could carry toxins like arsenic and boron from the old coal waste to the water. The ash ponds have been leaching for decades.

Instead, Missouri regulators required Ameren to test for chemicals and study the groundwater flows near the plant. Ameren has moved to compact its coal ash and cover old coal ponds, a controversial move some environmentalists have said is not enough, according to the St. Louis Post-Dispatch.