In 2015, the federal government tightened regulations around how power producers manage coal combustion residuals (CCR), and the waste industry speculated that a fair number of municipal solid waste landfills (MSW) would begin taking these materials. But what happened is most utilities set up their own disposal sites to replace impoundments they were discharging to before. However, two recent federal milestones may mean more MSW landfills will move into this space, according to some industry experts.

Meanwhile, while Subtitle D landfills can accept CCR, managing it responsibly can be complex, and some states are creating their own rules to further clamp down on disposers. Still, CCR generators and some MSW landfills see opportunity; while coal ash generation falls, its value for beneficial use rises.

Co-disposing CCR waste, especially residuals from flue gas (FGD), with MSW can present challenges. FGD contains calcium sulfite and calcium sulfate, which bacteria can use in the absence of oxygen to degrade organic waste. A byproduct is hydrogen sulfide, which is flammable and very odorous, says Jeff Murray, senior project manager at HDR.

“MSW landfills receiving CCR waste with FGD would need to be prepared to efficiently collect landfill gas and to implement other controls to prevent odor or impacts to human health and the environment,” he says. “Mixing MSW and CCR [rather than segregating it] comes with potential issues, particularly with fly ash and FGD components.”

With FGD, differences in CCR and MSW leachates present potential for unfavorable interaction. Sulfite and sulfate could promote hydrogen sulfide generation at locations where it is mixed with MSW, such as at pump stations, lined lagoons or storage tanks.

With fly ash, when it’s introduced to solid waste, the fines can potentially clog leachate collection systems, and it may also interfere with leachate infiltration to the collection system. Additionally, it may impact gas collection, as the material can restrict gas movement as gas tries to get through it. 

Fly ash also produces heat, which is even of more concern when mixed with MSW because potential reactions could inhibit gas generation, explains Rick Buffalini, vice president at Civil and Environmental Consultants, Inc.

Meanwhile, market demand for beneficial coal ash is incentivizing power producers to hold onto it.

But two federal milestones will further increase demands on utilities that take on the complex task of managing this material. These developments may force more closures, which could open opportunities for MSW landfills, projects Buffalini.

One milestone requires landfills and impoundments to submit groundwater quality information for the first time, as of the first quarter of 2018. They must close if they exceed groundwater quality standards.

Also, by October 2018, these sites must submit information around new location restriction requirements. For instance, they can’t be located in wetlands, in unstable areas or on fault areas.

Individual states are tightening their rules, too. North Carolina, after a large unintended coal ash release, began prohibiting construction of new and expansion of existing CCR impoundments on or after July 1, 2014. It established timeframes for eliminating discharge of CCR and stormwater into impoundments. And it required facilities to convert to disposal of dry fly ash and bottom ash in lined, permitted facilities.

Georgia requires landfills get approval of a CCR management plan from Georgia’s Environmental Protection division of the Department of Natural Resources. The plan must address fugitive dust and requires additional groundwater monitoring.

Six MSW landfills in Georgia take coal ash, collectively reporting receiving 1,525,917 tons in 2017. Five of these landfills comingle CCR and nonCCR, though they take some precautions. For instance, one of them limits CCR that can be blended to 33 percent.

“We are receiving a lot of out-of-state coal ash from Duke Energy in the Carolinas and from Florida utilities,” says April Lipscomb, Southern Environmental Law Center attorney. “Even though the Environmental Protection Agency is allowing coal ash to be treated like MSW, we believe there are extra protections needed.”

Republic Services applied for permits that would have allowed it to haul coal ash into Broadhurst Landfill in Wayne County, Ga. But it withdrew the applications in April 2017 after receiving community pushback.

Due to operational challenges, associated costs and the trend where utilities are holding onto their ash, it remains to be seen if more MSW landfills will enter this space.

“Whether it makes sense to take coal ash will depend largely on market. You will have extra costs tied to gas and leachate quality control as well as controlling odors and dust. So, it comes down to if you can get a price to justify expenses, as with many special wastes,” says Buffalini.