Duke Energy's Asheville Steam Electric Generating Plant coal ash ponds. The DEQ has ranked the ponds as risk.
In this image of the Asheville Steam Station, the coal ash basins are clearly marked. Lake Julian is the water body in the top right of the image. The French Broad River is visible adjacent to the red dotted line furthest to the left. Photo courtesy Duke Energy.


The General Assembly ordered the Department of Environmental Quality to rank the state’s coal ash ponds in order of hazardous risk. But it turns out that’s not so easy.

By Catherine Clabby

On first blush, the task sounds simple enough.

As required by state law, North Carolina environmental officials created a system to assess health and environmental risks from coal ash dumps at 10 Duke Energy power plant properties. Then they applied that risk assessment to work up draft decisions on when a dump must close and how aggressive a cleanup it requires.

Dig into that task just a bit, however, and complexity blooms.

Duke Energy’s coal ash dumps are far from identical. In 2014, after the coal ash spill into the Dan River, the utility reported that its smallest repository in North Carolina stored 9,000 tons of coal ash and the largest stashed 22,270,000 tons.

Concentrations of potentially harmful compounds in the dumps – arsenic, selenium, vanadium and magnesium among them – vary, depending on the types and amount of coal burned. Proximity of the dumps to people’s drinking-water sources differs too, below and above ground.

Duke Energy's Asheville Steam Electric Generating Plant coal ash ponds. The DEQ has ranked the ponds as risk.
Duke Energy’s Asheville Steam Electric Generating Plant coal ash ponds. DEQ has ranked the ponds as high risk. Photo courtesy Duke Energy

The stability of dams to hold it all in place, when they are present, is not consistent either.

Add to all that the fact that not all the data needed to fully characterize each pond has yet been acquired, including information on how polluted ground water is most likely to travel underground from some sites, and the task grows ever more complicated.

Despite all that, state officials say they are developing a bull’s-eye aim in ranking the health risks posed by the coal ash compounds.

And now the public has a chance to weigh in on the Department of Environmental Quality’s draft dump-ranking approach.

During March, DEQ will hold public meetings in all counties with Duke Energy coal ash dumps. [pullquote_right]People can submit written comments online, in person, by email or by post through April 18.[/pullquote_right](For dates and locations, see map below.)

The draft DEQ rankings could change, depending on the comments and additional scientific data DEQ receives, department officials have stressed.

Exceeding standards

Already, groundwater contamination beneath all Duke Energy sites with coal ash dumps has been shown to exceed this state’s water-safety standards. Some metals contributing to that contamination, in different contexts, have been linked to human illness.

There is little evidence to date that metals released from coal ash sites have caused people to get sick, said Damian Shea, an N.C. State University environmental to­xicologist who has helped detect types and amounts of toxic chemicals within coal ash in North Carolina, Tennessee and China.

The Southern Environmental Law Center, a longtime critic of North Carolina’s supervision and regulation of Duke Energy’s coal ash waste, says the state should scrap the ranking process and simply order the utility to dig up all its coal waste and dispose it safely elsewhere. All power utilities, including Duke Energy, have agreed to that in South Carolina, said Frank Holleman, a senior attorney with SELC.

“The state should wake up to the risk and danger of continuing to store coal ash next to water arteries,” Holleman said.

High, intermediate, low

North Carolina officials have argued that accurate risk assessment is possible and will protect people and the environment. In addition, cleaning up the Duke Energy dumps is going to be expensive: between $2 billion and $10 billion depending on the closure methods imposed. Limiting the utility’s costs will reduce Duke Energy rate increases that state residents will have to shoulder downstream, DEQ Assistant Secretary Tom Reeder has said.

The new risk rankings, when final, are expected to determine the fate of coal ash dumps at 10 Duke Energy power plant locations. In the draft rankings, published in January, 12 dumps at four Duke Energy properties are labeled intermediate risks. If that ranking holds, all coal ash must be removed from each by the end of 2024.

The N.C. Dept. of Environmental Quality is holding hearings in each county with a coal ash pond on those ponds’ ranking for cleanup. Click on the icon for each Duke Energy property to see dates and locations where the 6 pm meetings will be held. At sites with multiple coal ash ponds, the highest draft risk ratings are listed here.

Four dumps at three sites currently are designated low risk, meaning they must be shuttered by the end of 2029. Protective steps will be required at sites deemed low risk, but digging up the coal ash there will not be required.

For now, DEQ regulators have left nine dumps at six sites in a sort of limbo, labeling them “low-to-intermediate.” DEQ did so after finding “gaps and deficiencies” within some required data submitted by Duke Energy regarding the sites.

DEQ officials said they need more data specifying where ground water moves in the vicinity of all the Duke Energy faculties, information that is not simple to develop for sites, and more evidence whether toxic compounds detected in water near dumps originate from coal ash or from other sources, including natural sources.

“The biggest holes we’re waiting to fill are on two things on underground water plumes, Reeder said. “We know there is contamination under each one. Where is that contamination and how far has it spread? And what is the background level of the compounds we are worried about?

An aerial shot of the Dan River Steam Station, the power plant whose ash spilled into the Dan River. Duke stores coal ash, a byproduct of electricity generation, in wet ponds. Photo courtesy Duke Energy
An aerial shot of the Dan River Steam Station, the power plant whose ash spilled into the Dan River. Photo courtesy Duke Energy

“Heavy metals occur naturally in North Carolina. We know they are slightly elevated in some wells. We don’t have enough information to determine if those wells are being affected by the Duke sites.”

One thing that won’t change from this ranking process is the status of four Duke Energy power plants designated as high priorities for closing with passage of the 2014 Coal Ash Management Act. That law was part of the state response to the Dan River Steam Station in Eden. After a storm pipe ruptured, 39,000 tons of coal ash poured into the Dan River, with some ash traveling 80 miles to the Kerr Reservoir in a matter of days.

Dumps at the Dan River facility and three other sites DEQ has labeled high risk in the rankings were previously ordered to be shuttered by the end of 2019, with all coal ash dug up and removed.

One and only

North Carolina can’t turn to another state for technical guidance on its quest to rank the risk posed by the coal ash dumps, because no one else has attempted to assess risks posed by multiple dumps individually. Despite that, DEQ is leaning on standards and practices widely used to detect and measure human health risks, said Shea, the N.C. State University environmental to­xicologist helping to identify coal ash content.

“In general, the state is taking a logical approach to understand the chemicals of concern, the source of those chemicals and what their potential pathways are to people,” Shea said. “That is a logical and standard approach.”

The approach can be successful, he stressed, only if all the data the state uses are accurate and relevant. Having not reviewed the data, he could not assess them.

In preparing the current rankings, DEQ says it scoured site assessments and corrective-action plans produced by Duke Energy, as well as results from state inspections at the impoundments, water-sampling results, drinking-water well surveys, groundwater-movement studies and dam safety checks. The regulators focused particularly on threats in three areas identified as “key factors”: groundwater, surface water and structural stability at the impoundments, specifically of dams.

“If any of the key factors did not rate out as low, they went into the intermediate category,” Reeder said.

In each key factor, conditions considered to pose a low risk include the following:

Low risk to groundwater Having zero people using wells that may be contaminated by coal ash waste due to the underground movement of water near the site or due to evidence of coal ash contamination.
Low risk to surface water Being located outside of a 100-year floodplain (where floods are predicted to occur at least once a century) or having impoundments contained by embankments that feature engineered spillways.
Low risk for dam instability Having received no deficiency notices at the last required inspection

Other factors were also considered in the rankings, including the amount of coal ash on a property; dump depth, especially how close it gets to a water table; the toxicity and known cancer-causing effects of contaminants in the dump; risk of people being exposed to tainted soils; the type of wastewater treatment at sites; and proximity to waterways that flow into drinking-water sources.

Enough data?

Concern over the safety of these coal ash sites swelled after the 2014 spill.

In May 2015, Duke Energy pleaded guilty to nine criminal violations of the Clean Water Act at several of its North Carolina sites, including the Dan River site, and agreed to pay a $68 million criminal fine and to spend $34 million on environmental projects in North Carolina and Virginia.

Tom Reeder, the Assistant Secretary for the Environment. I
Tom Reeder, the assistant secretary for the environment. Image courtesy DENR

State regulators have tested private and public water-supply wells within 1,500 feet of each coal ash impoundment for pollutants commonly found in coal ash. Out of the 476 wells sampled, according to the agency, 424 well owners received a “do not drink” health risk evaluation from the N.C. Department of Health and Human Services.  The metals vanadium or hexavalent chromium, or both, were detected in 369 tested wells. Among them, 12 wells had contaminates at levels exceeding federal safe drinking-water standards, Seven exceeded levels for lead and five for arsenic.

Again, it is not yet known if those substances originated from coal ash or from other sources.

Katie Hicks, associate director of Clean Water North Carolina, said if the state doesn’t have all the data it needs to make a definitive link between coal ash and risky contaminants in well water, it’s not unreasonable to take steps to protect people from the dumps, just in case.

“If you don’t have the data, then err on the side of people’s health,” Hicks said. “Use the precautionary principle.”

DEQ continues to receive data it needs to better understand where contaminants released by the dumps are most likely to travel vertically and horizontally, as well as background levels for toxic compounds detected in the dumps.

“Duke is providing the department with data and we are providing our feedback on an almost weekly basis. Based on our current status, we believe that we should have both of these questions answered for all 14 facilities sometime early this summer,” said Crystal Feldman, DEQ’s deputy secretary for public affairs.

Shea said that after the rankings – and even after the dump cleanups are completed – state regulators would be wise to continue to monitor water and people’s health near the coal ash sites. That would help regulators assess whether their conclusions about the likely paths of contaminants were correct and whether closing the individual dumps had beneficial effects.

It could also help inform other governments about the effectiveness of the North Carolina approach.

“We would be remiss not to continue to follow up and not try to understand how mitigation efforts may reduce exposures,” Shea said.

Figuring out how to judge threats from stockpiled coal ash, after all, is not just a challenge here. More waste from coal-fired power plants gets produced every year.

And coal ash is the second-largest industrial waste stream produced in the United States.

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Catherine Clabby

Catherine Clabby (senior environmental reporter) is a writer and editor. A former senior editor at American Scientist magazine, Clabby won multiple awards reporting on science, medicine and higher education...