A Santee Cooper employee works to install an AquaDam on a coal ash impoundment located at the Grainger Generating Station in September 2018. The Waccamaw River flooded in the aftermath of Hurricane Florence and threatened to overtop or breach the impoundment, which Santee Cooper was in the process of excavating.
A Santee Cooper employee works to install an AquaDam on a coal ash impoundment located at the Grainger Generating Station in September 2018. The Waccamaw River flooded in the aftermath of Hurricane Florence and threatened to overtop or breach the impoundment, which Santee Cooper was in the process of excavating.

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This story is part of a 12-part investigation by the Chicago Investigative Project in the graduate program at the Medill School at Northwestern University.


Just upstream of Alabama’s Mobile Bay sits a vast region of wetlands known as the Mobile-Tensaw Delta, home to one of the most diverse ecosystems in the United States. As well as 21 million cubic yards of wet coal ash. 

The J.M. Barry Power Plant has been a flashpoint between environmental advocates and the state utility, Alabama Power, for years. It is a case study in the continuing risks posed by coal ash disposal: 600 acres of wet coal ash that’s already leaching toxic metals like arsenic and cobalt into groundwater, sitting in an open pit, on a riverbank, in one of the rainiest places in the United States, 25 miles north of the hurricane-prone Gulf of Mexico.

As of April 2021, 172 coal ash impoundments nationwide sat on land deemed vulnerable to floodwaters, according to Earthjustice’s Coal Ash Rule Compliance dataset. Based on data that companies with coal ash must report, these impoundments are in what the Federal Emergency Management Agency calls a “100-year floodplain” — meaning there’s a one-in-a-hundred chance the area is flooded each year. Scientists have warned that climate change will make these floods much more frequent in the future. 

Extreme weather events can cause floods that overtop or even cause impoundments to fail and spill coal ash into lakes and waterways, as was the case at North Carolina’s Lake Sutton during Hurricane Florence in 2018. And even without a catastrophic failure, flooding that raises the water table more than a few feet can inundate groundwater with toxic contaminants.

The federal Environmental Protection Agency has mandated the closure of most unlined coal ash impoundments but largely given utilities broad leeway on when closure will occur or whether the ash will be removed or left where it is.

There’s also evidence that the method for closing ash ponds preferred by most utilities, wherein ash ponds are dewatered and covered with an impermeable cover — known as “cap-in-place” — is ineffectual at preventing continuing contamination of waterways and groundwater. Advocates fear this could be the case at the Barry power plant in Mobile Bay, where the company plans to leave ash in place. 

“All of these environmental aspects put it in a really concerning location,” said Cassie Bates, program coordinator for local advocacy group Mobile Baykeepers. “Flooding of the river can be a great concern given we’re in coastal Alabama. Impacts from hurricanes and tropical storms are always imminent. The combination of these things make it not a really viable place to leave that much waste sitting on the side of the river.”

Coal ash 101: Everything you need to know about this toxic waste

As coal plants close nationwide, they leave behind nearly a billion tons of toxic coal ash. The Medill School of Journalism spent months investigating the coal ash threat and how regulators, companies, and environmental groups are handling it. 

Here are the basics that will help you understand this looming threat.

What is coal ash?

Coal ash is the toxic byproduct of burning coal to generate electricity. It contains heavy metals that can contaminate groundwater, lakes, and rivers. 

Where is coal ash located?

Coal ash is stored in more than 700 ponds and landfills nationwide, most of them unlined. Ash can also be recycled — known as “beneficial reuse” — in which it is used to make concrete or build roads. 

What is the Coal Combustion Residuals (CCR) Rule?

In 2015, the EPA established rules for coal ash units, requiring companies to test groundwater, remediate contamination, and make plans to close the units. Companies have to post groundwater monitoring data and closure plans online.

The rule excludes hundreds of “legacy ash ponds” that closed before the federal rule took effect in 2015, yet these ponds are still causing serious groundwater contamination. The rule also does not cover coal ash that was over decades dumped and scattered around coal plant sites and even surrounding areas, often used to build up berms or fill in land.

Is coal ash contaminating our water?

Data posted by companies shows that contaminants around coal ash ponds frequently exceed limits set by the EPA, sometimes exponentially. Private wells used for drinking water can be and have been contaminated by coal ash. Rivers and lakes used for recreation and municipal water supplies can also be contaminated by coal ash.

What’s in coal ash?
Boron

Boron is linked to reproductive problems like low birth weight and is also toxic to aquatic life.

Lead

Lead is a potent neurotoxin linked to swelling of the brain and nervous system damage.

Lithium

Lithium is linked to liver and kidney damage as well as neurological diseases and birth defects.

Arsenic

Arsenic is linked to nervous system damage and higher rates of cancer. 

Molybdenum

Molybdenum is linked to gout, high blood pressure, and liver diseases. 

Cobalt

Cobalt is linked to thyroid damage and blood diseases.

How is a coal ash pond closed?

Coal ash sites need to close after getting their final shipment of coal ash, if they are polluting groundwater above certain standards, or if they fail to meet other safety criteria. The rules say all unlined ponds needed to stop accepting waste by April 2021, though some requested exceptions and have continued filling with coal ash. 

Cap-in-place closure

A protective cover is placed over the coal ash so rainwater doesn’t get in and cause flooding or increased leaching into groundwater.  If the coal ash is left in contact with groundwater or permeable rock, it can continue leaching contaminants even when capped.

Removal closure

Coal ash is excavated from a pond, dried, and moved to a lined landfill above the water table. Companies may be able to build a landfill on the power plant site. Shipping coal ash to landfills off-site means heavy truck traffic or shipping by barge or rail.

Who pays for coal ash cleanup? 
Companies

The owners of coal ash sites — utilities or power companies and their shareholders — can pay the cost of coal ash cleanup, often hundreds of millions or even billions of dollars across multiple sites. 

Ratepayers

Utilities can seek approval from state public service commissions to bill the cost of coal ash cleanup to ratepayers. They can even seek a profit as a portion of the costs. 

Government

If coal ash is designated a Superfund site, the EPA can make the responsible parties — utility or power companies — pay for the cleanup. The government can also pay for the cleanup from a pool of Superfund money, especially if the companies no longer exist or can’t pay. 

Compiled by Sruthi Gopalakrishnan.

‘Disasters waiting to happen’

Extreme precipitation can cause coal ash in impoundments to overflow the pit or breach the dams holding it in place.

Fifty-four impoundments nationwide have been given a hazard rating of “significant,” meaning the failure of the dams keeping the ash in place would result in economic loss, environmental damage and disruption of lifeline facilities like telecommunications, the electrical grid, and hospitals. Twelve are rated “high” hazard, meaning their failure would probably cause loss of human life.

Two of the “significant” hazard ponds were located at Duke Energy’s L.V. Sutton power plant in Wilmington, North Carolina. In 2018, surging floodwater and torrential rains caused by Hurricane Florence flooded the Cape Fear River and overtopped an ash basin that spilled into neighboring Sutton Lake. In an email, Duke Energy spokesperson Bill Norton said the Cape Fear spill and the separate release of 2,000 cubic yards of coal ash from a landfill under construction did not lead to significant contamination or violate state water quality standards.

A similar crisis was averted during that same hurricane in South Carolina when officials from state-owned utility provider Santee Cooper realized rising water levels in the Waccamaw River could overtop two partially excavated ash ponds at the former Grainger power plant near Conway, South Carolina. 

To prevent that from happening, Santee Cooper officials requisitioned an AquaDam, a water-filled barrier used for flood control, to make the dike surrounding the ash ponds taller. A police escort accompanied the temporary dam as it was trucked from Louisiana to Conway; Santee Cooper crews and state National Guard troops installed the AquaDam with hours to spare. 

Frank Holleman, an attorney with the Southern Environmental Law Center, views Hurricane Florence as a warning.

“It illustrates for these sites that they have not capped, or they won’t have excavated, or they plan to cap-in-place — they are just setting up disasters waiting to happen,” Holleman said. 

The Barry plant is another impoundment with a “significant” hazard rating, and Mobile Baykeeper documented river levels within a few feet of the top of the dam walls following a high-water event in February 2016. 

“It just takes the, for lack of a better word, right storm in the right place to be a disaster,” Bates said. 

A Santee Cooper employee works to install an AquaDam on a coal ash impoundment located at the Grainger Generating Station in September 2018. The Waccamaw River flooded in the aftermath of Hurricane Florence and threatened to overtop or breach the impoundment, which Santee Cooper was in the process of excavating.

Hidden risk   

At Sutton Lake in North Carolina, contamination may have been going on for years: A 2019 study from Duke University found coal ash in sediment collected from the lake bottom in 2015 contained similar concentrations of coal ash contaminants to samples collected after the storm, suggesting coal ash contaminants had already been released into the lake prior to the 2018 dam breach. 

The authors argued that high water flows from past storm events could have moved coal contaminant particles into Sutton Lake, which had higher levels of some contaminants than sediment found in streams affected by coal ash spills in Kingston, Tennessee in 2008 and on North Carolina’s Dan River in 2014 — arguably the two worst coal ash disasters in American history. 

They said their findings highlighted the risk of “large-scale unmonitored spills of coal ash solids” from impoundments following major storm events — essentially, that coal ash ponds were flooding unmonitored far more than anyone knew about it.

“That’s kind of the scary thing, that many hundreds of lakes like this located near coal ash ponds in the U.S. could have experienced that,” said Avner Vengosh, the Duke professor who led the study.

Norton of Duke Energy said the utility “strongly disagrees” with the study’s conclusions, citing low levels of selenium, a contaminant found in coal ash, in samples of fish tissues taken by Duke at Sutton Lake. 

Mobile Baykeeper has found coal ash floating in and around the Barry impoundment. Samples collected by the group in 2016 and 2018 were found to contain 55% to 80% fly ash, according to an analysis by an independent laboratory. 

Bates at Mobile Baykeeper suggested the ash could have ended up in the water in several different ways not involving the “wet” coal ash impoundments, including dry ash blown from a surface landfill also at the Barry plant or direct discharge of wastewater into the Mobile River, though these would pose their own issues. 

Southern leadership  

Some Southern states have moved to excavate their coal ash, in large part due to legal intervention by the Southern Environmental Law Center and other groups. In late 2019, Duke Energy reached a settlement with the state of North Carolina that requires Duke to dig up nearly 80 million tons of coal ash and move it to lined storage; that represents nearly all of the state’s wet ash. North Carolina allowed the utility to leave 3.3 million tons of ash in place, finding it was far away enough from the floodplain and did not pose significant risk to the state’s lakes and rivers. 

All three of South Carolina’s coal-fired power utilities had agreed by 2015 to excavate coal ash from unlined pits; Santee Cooper completed its excavation four years ahead of schedule, which Holleman credits as helping prevent disaster in 2018. According to Santee Cooper spokesperson Nicole Aiello, the ash ponds were already 87% excavated at the time of the AquaDam mission.

Alabama has not moved to excavate: The Alabama Department of Environmental Management issued a permit in 2021 allowing Alabama Power to close the Barry impoundment in place, despite protests from the Southern Environmental Law Center and Mobile Baykeeper that the state regulator’s permitting program was “considerably weaker” than federal regulations and had not been approved by the federal Environmental Protection Agency.

Great Lakes risk 

As many coal plants were located on the shores of the Great Lakes, coal ash flooding into the lakes and tributaries is a serious risk, highlighted in a June 2022 report by the Environmental Law & Policy Center that focused on how climate change could exacerbate rainfall and high lake levels in southern Lake Michigan. 

The report looks at risks from a “combination of high lake levels and extreme storm events,” and notes that the Federal Emergency Management Agency and Army Corps of Engineers are both updating their flooding predictions for the region. 

NRG’s coal plant in Waukegan in northern Illinois, Alliant’s Sheboygan coal plant in Southeast Wisconsin, and the shuttered State Line coal plant in Northwest Indiana are among the sites where, the report notes, the increased risk of flooding due to climate change could spill coal ash into Lake Michigan especially if lake levels rise. 

Coal ash ponds at the Alliant plant, which is scheduled to stop generating this year, have been poorly maintained, according to the report, and the lakeside bluffs are vulnerable to erosion related to rising lake levels and heavy storms. At Waukegan, the report says, “flooding could infiltrate the adjacent areas containing coal ash, pose a risk to the structural integrity of the ponds, and cause contaminant leaching from ash outside of the ponds.” 

The State Line plant just south of Chicago was closed in 2012, and there are no coal ash ponds subject to federal rules. But coal ash was known to be scattered across the site, environmental experts note, and flooding of Lake Michigan could carry that ash into the lake. 

“Given the increased flood risk due to climate change, local and state officials should investigate the levels of soil contamination and how rising water levels and extreme weather could affect the site and surrounding community,” wrote the Environmental Law & Policy Center.

‘Keep it dry’ 

Much of the damage that can arise from having coal ash in the floodplain can happen even without an extreme weather event or catastrophic breach. 

That’s because the only thing coal ash needs to cause groundwater contamination is contact with water. Flood conditions can raise the water table and contaminate groundwater that encounters the bottom of the coal ash impoundment.

To get an idea of how coal ash impoundments work, picture a paper coffee filter buried partially in soil, filled to the brim with ground coffee. 

The coal ash is usually mixed with water and stored in unlined pits that often allow contaminants in the coal ash to leach out of the pit and into groundwater, even while the ash stays in place.

“Whenever the water gets into the waste, it dissolves metals and other contaminants, and, as the water goes back down, that flows out the bottom and into the groundwater,” said Mark Hutson, a geologist who’s provided expert consultation to the Southern Environmental Law Center for coal ash impoundments in states including North Carolina, Georgia, Indiana, and Alabama — including the Barry impoundment.

Hutson said preventing coal ash contamination requires thinking about water flow from all directions, not just from precipitation.  

“The key to a permanent disposal of fly ash, if you’re going to put it into a disposal, is to keep it away from water, keep it dry,” Hutson said. “These things are floodplains because as the water comes up during high water events, it can come up through the unlined bottom [of the coal ash impoundment] and enter into the waste.”

Hutson’s report on the Barry impoundment found the ash there was already saturated with groundwater, while Alabama Power’s plan to cap the ash in place would leave some of it below sea level. In the case of a 100-year flood, Hutson predicted, floodwaters would rise to 15 to 16 feet above sea level. 

Federal regulations require at least 5 feet between the bottom of a coal ash impoundment and the uppermost level of the uppermost aquifer, a standard the Barry site does not meet. But Hutson says even adherence to the EPA’s rule, at least historically, would not resolve the issue of groundwater contamination.   

“The problem is all it requires if the impoundment doesn’t meet the 5-foot separation rule that they close it,” Hutson said. “And utilities tend to want to close it by leaving it there.”  

This year, the EPA has taken a stricter stance on impoundments where coal ash sits in groundwater, rejecting requests for extensions on closing coal ash ponds where ash was found to be in contact with groundwater. A consortium of utilities including Southern Company, which owns Alabama Power, has challenged the EPA’s decisions in federal court. 

Hutson’s report highlighted another related concern at Plant Barry, corroborated by a separate report commissioned by Mobile Baykeeper: the long-term stability of the dams holding the coal ash in place. Even if ash were to be removed from groundwater, and even if the impoundment is never overtopped, erosion from the Mobile River makes it increasingly likely the berm will eventually fail, releasing some of that 21 million tons of coal ash into the river. 

What would that look like? Hutson’s report and Bates used the same word: catastrophic.

Joshua Irvine

Josh Irvine graduated from Northwestern University with a degree in journalism in 2022. He currently reports on poverty for the Telegraph Herald of Dubuque, Iowa, as a Report for America corps member.