Coal ash toxins are leaking from ponds at Dominion’s Chesterfield Power Station in Virginia into recreational areas, according to the Southern Environmental Law Center, spelling out the latest bad news for coal ash impoundments. Similar events are forcing ponds to shutter nationwide.
The sweeping demise of these impoundments will drive a radical shift in how billions of tons of coal ash are managed. But the trend will likely mean big opportunity for landfill operators who can now accept and treat the material with minimal restrictions beyond existing ones to handle MSW.
But there are surrounding issues that run deep—communities are fighting landfill operators’ early efforts to capitalize on these opportunities. Meanwhile the supply of the waste from accumulative years of electricity generation is growing, and this metal-laden material has to go somewhere—somewhere where it can be carefully contained and stored. Landfills will have to be highly adept at managing issues like moisture, runoff and dust to ensure a better system of dealing with the massive tonnage.
“Coal combustion residual (CCR) is second to MSW in terms of volume of waste generated in this country. We produce almost as much CCR as garbage,” says John Daniels chair of the Department of Civil and Environmental Engineering at the University of North Carolina, Charlotte. Virtually every coal ash impoundment will be required to close in the foreseeable future, Daniels adds.
There are 150 million tons floating through North Carolina alone, and that state, the first to adopt a coal management act, generates another 4 million tons a year. Nationally the industry generates upward of 120 million tons annually.
Some stakeholders see moving the material to well-lined landfills as an alternative to mitigate what has gone on at troubled impoundments.
Landfills deal with coal ash quite differently than it has been handled in ponds
“Historically coal ash was mixed with water and sent to a pond. The ash settled and the water was sent to the nearest river,” says Daniels.
“Now we collect ash, put it in a truck and compact it at the landfill, which is called dry managing, done to minimize leachate. Making it water repellant can be a further barrier to leachate and infiltration,” he says.
Landfill disposal has gotten pushback from skeptical environmentalists as seen in cases such as when Republic pursued an opportunity to accept coal ash in Georgia. Waste Connections has faced as big a fight in North Carolina’s Anson County.
Other stakeholders continue to pursue the material. Charah, branded mainly as CCR managers, is now building a beneficial use project under the laws and regulations of North Carolina to dispose of Duke Energy’s ash at Brickhaven mine in North Carolina.
Opponents say arsenic and selenium can leach out and contaminate ground water.
But Daniels says while ash, if mixed with water, can result in contaminant levels that exceed drinking water standards, coal ash overall has lower leachability than MSW.
Managing fugitive dust
What landfill operators need to be cautious of is fugitive dust, a fine granular material that is a source of airborne pollution. Mixing ash with polymers and other chemicals better manages the dust; polymers can bind particles to keep them from floating away, says Daniels.
US EPA’s final coal ash rule, signed December 2014, requires landfill operators to develop a fugitive dust plan. This could, for a few examples, include locating coal ash inside an enclosure; operating a water spray or fogging system; or using wind barriers.
Coal ash can serve as a landfill resource
It can be used as daily cover though doing this successfully depends on how dust and moisture are managed.
“You will need to know whether you are dealing with Class C or Class F ash as Class C ash will have lower hydraulic conductivity with more water runoff. And you will need very good dust control,” says Daniels.
Meanwhile, a few researchers are studying coal ash from a recovery perspective, looking for ways to retrieve valuable metals. Ross Taggart, a PhD student at Duke University Department of Civil and Environmental Engineering, is working on technology to try and achieve this goal. He is considering disposal opportunities too.
“The potential for leaching of toxic metals is one reason landfills are closing and relocating. However if you could bring toxic elements below certain thresholds the ash could be disposed of more safely—either on site or at a different landfill.
“I am looking into possible ways to efficiently recover valuable metals from coal ash that, at the same time, may enable residual ash to be disposed of safely without leaching.”