“In looking at how to come into compliance with those two rules, utilities are also looking at the new regulatory landscape that’s defined by the [federal] Clean Power Plan,” says James R. Roewer, executive director of the Utility Solid Waste Activities Group (USWAG). “They’re looking at which of the coal-fired units are going to continue to operate after the CCR rule controls, after the ELG rule controls and after the limits established on CO reductions of the Clean Power Plan.”

In February, the U.S. Supreme Court granted a stay on the Clean Power Plan, halting its implementation pending a June review by the D.C. Circuit Court of Appeals and likely delaying until fall a decision by that court. Despite that, 19 states are continuing their planning to implement it, while 20 states are suing the EPA.

Wet Waste, Dry Waste

The new ELG rule was finalized in September 2015. ELG rules have been in the Clean Water Act since the 1970s, “but we haven’t made any major changes to it since 1982,” says Colleen Layman, resources business-group water principal for HDR Inc., Omaha. “Everyone’s seeing the new rules as a challenge to the power industry to keep coal-fired power relevant as we move forward into more renewables. They’re competing with different and cleaner forms of power.”

The development of new air-quality-control systems in recent years has reclassified coal plants’ waste streams. “Wastewater systems in most [National Pollutant Discharge Elimination System] permits have been lumped as low-volume wastewater because there was never a category to deal with it before,” Layman says. “The new rule breaks out those wastewater streams, which had become standard in many power plants, and gives them their own category with their own regulations.”

While the ELG rule is focused on liquid wastes, the CCR rule deals with solid coal-combustion by-products: fly ash and bottom ash. For decades, utilities have sluiced their ash to impoundments. The practice largely escaped public notice until December 2008, when a catastrophic spill at the Tennessee Valley Authority’s (TVA) power plant in Kingston, Tenn., flooded more than 300 acres and released coal ash into two rivers (ENR 1/5/09 p. 12).

That spill prompted the EPA to assess coal-ash impoundments and gather information from facilities managing coal ash nationwide. A 2010 proposed regulation to assess coal-ash disposal risks addressed the structural integrity of impoundments to prevent catastrophic releases; but, in February 2014, a broken stormwater pipe at Duke Energy’s ash pond, near Eden, N.C., leaked an estimated 27 million gallons of contaminated water into the Dan River. It wasn’t catastrophic like the Kingston spill, but it heightened concerns about ash pond storage (ENR 2/17/14 p. 8). The 2010 proposal, modified in response to questions received during the comment period, has been incorporated in the new CCR rule.

Dispose or Recycle

“Right now, we estimate that there is 1.5 billion tons of ash in disposal in the U.S., and that’s a very conservative estimate,” says Tom Adams, executive director of the American Coal Ash Association. The CCR final rule supports the responsible recycling of coal ash by distinguishing disposal from safe, beneficial use—and there’s a lot of interest in that, Adams says.

After municipal solid waste, coal- combustion products constitute the second-largest waste stream in the country, Adams notes. Total generation amounts to 125 million to 130 million tons a year. In 2014, 47% of the total ash generated was beneficially used.

Coal’s market share for electricity generation has declined to 33% today from about 50% a decade ago, but it’s not going away, Adams says. The U.S. Energy Information Administration projects the U.S. will be burning the same amount of coal in 2040 as we are today. “There’s clearly going to be coal combusted for the next 20-some years, which means we’ll have these residuals around for quite a while,” he says. But the CCR rule ensures that ground­water monitoring and leachate collection will remain major concerns for the owners of active ash ponds.

Still, the CCR rules are forcing some costly changes on coal-burning utilities. Ponds that were deemed inactive by October 2015 must be closed by April 2018. Ponds kept open will be closed once the utility converts to a dry system. “The vast majority of wet ponds in the industry will probably be closed in the next five to 10 years,” says Kevin De Lange, HDR Inc. senior vice president and waste practice leader.

“Many [power plants] have multiple ponds. They will close as many as they can, and, if they have to, they will keep one open. If they don’t need the pond open anymore, they can convert it to landfill,” De Lange adds. The rules “are basically creating a similar structure to municipal solid-waste landfills. The rules are a significant driver of additional cost to the utilities.”

The dry management of CCR is much less regulated than its wet management, De Lange observes. “The vast majority are converting from a wet to dry system and then creating dry landfills, if they’re staying open.” The conversion costs $10 million to $40 million at many plants, he adds.

Fly ash captured in an electrostatic precipitator or baghouse is dry. Wet management feeds ash into a sluicing system for transfer to a surface impoundment. Converting from wet to dry management means changing the fly-ash transport system. Boiler bottom ash is sluiced from a quenching tank, where it is already wet, to the ash pond. Engineering and construction work would consist of equipment modifications to produce dry products to be beneficially used or landfilled.

“A lot of engineers are doing a lot of work right now in terms of design of wastewater-treatment systems and redesign of the ash-management system,” USWAG’s Roewer says.

Utilities “are doing a very good job in general in complying, getting ahead of the game where they can,” says De Lange. TVA is retiring coal-fired units and adding emission controls to others. It will close 22 impoundments by 2022, a spokesman says. American Electric Power Co. “is in the midst of a multiyear plan to close, drain and permanently cap all but two of the company’s eight existing fly-ash ponds. We will close a total of 20 ash ponds,” says a spokeswoman. And Georgia Power plans to close all 29 of its ash ponds.