© 2023 St. Louis Public Radio
Play Live Radio
Next Up:
Available On Air Stations
The 88.5 FM KMST Rolla transmitter is operating at low power while awaiting a replacement part.

9 Questions Answered About Missouri’s Toxic Coal Ash Ponds

Labadie resident and environmental activist Patricia Schuba looks at the Labadie Energy Center through binoculars.
Eli Chen | St. Louis Public Radio
Labadie resident and environmental activist Patricia Schuba looks at the Labadie Energy Center through binoculars.

Every Missouri utility that’s dumping waste from coal-fired power plants into massive pits in the ground has posted data that shows significant levels of nearby groundwater contamination, according to an analysis by the Washington University Interdisciplinary Environmental Clinic.

Missouri has never regulated these pits, known as coal ash ponds, even though they’ve existed for more than 50 years.

Since the 2015 federal rule on coal-combustion byproducts has made states the primary enforcers of coal ash regulations, Missouri has drafted a plan for overseeing ponds and landfills that store the waste.

The Missouri Department of Natural Resources is asking for feedback on its plan until March 28.

What is coal ash waste, and why are they dumped in “ponds"?

Coal ash waste is material that remains after coal has been burned at a power plant. The materials contain toxic chemicals, such as arsenic, lead and mercury.

According to the Environmental Protection Agency, the waste can take several forms. Fly ash is a fine, powdery material that’s made of the mineral silica, and it’s created when finely ground coal is burned in a boiler. Bottom ash is a coarse material that collects at the bottom of the coal furnace. Boiler slag is molten bottom ash that forms at the bottom of slag tap and cyclone-type furnaces. Flue gas desulfurization is material that takes the form of either a dry powdery material or wet sludge containing calcium sulfite or calcium sulfate.

READ MORE: Data shows massive pits of coal waste from Missouri utilities polluted groundwater

Coal ash has traditionally been dumped in basins, because power plants use water to process them. After the Tennessee Valley Authority coal ash spill in 2008, many electric utilities have sought for or adopted technologies that don’t require water to handle coal ash.

How large are these coal ash ponds? Are they located near bodies of water?

Missouri has 36 coal ash ponds, and they vary in terms of size. Among the smallest is a pond containing boiler slag at Associated Electric Cooperative’s Thomas Hill Energy Center that is 16,000 cubic yards. Ameren Missouri has some of the largest ponds, such as Labadie Energy Center’s pond full of bottom ash, which is 15.8 million cubic yards.

Many of the ponds — including those belonging to Ameren, Kansas City Power & Light and Associated Electric Cooperative — are located close to the Mississippi and Missouri rivers. Some are near bodies of water, such as Thomas Hill Reservoir in Randolph County, which is used for recreation.

Why is coal ash waste classified as “non-hazardous waste,” and how does this affect the way it’s regulated?

The coal industry lobbied heavily against the EPA’s proposal to label coal ash waste as “hazardous.” The American Coal Ash Association argued that the classification would make it difficult for companies to recycle coal ash. The waste can be used to make concrete, roof shingles and drywall.

Because the EPA has classified coal ash as “non-hazardous,” states must be primary enforcers of coal ash regulations. Meanwhile, under the federal rule, utilities have been required to conduct groundwater monitoring tests and post them online.

Oklahoma is the only state that’s had its regulatory plan for ponds approved since the 2015 federal rule. Missouri and other states are still drafting coal ash regulations to be approved by the EPA. The Missouri DNR expects its plan to be effective at the end of September this year.

How does the state currently regulate coal ash waste?

Missouri regulates coal ash landfills but has never had regulations for ponds. Rules for landfills have been in place since 1997. It requires utilities to monitor groundwater near landfills, construct them away from seismic zones and other potentially hazardous areas and specifies how liners must be constructed to avoid environmental contamination.

What does groundwater-monitoring data from Missouri utility companies show about area water quality?

According to an analysis from researchers at Washington University, groundwater samples taken near all of the ponds that are actively receiving coal ash waste have shown levels of harmful chemicals that exceed state and federal drinking-water standards. At the Rush Island Energy Center, for example, there were 28 cases in which tests showed levels of arsenic above federal standards, and levels of the chemical reached more than 25 times the EPA drinking-water limit near its only pond.

Could groundwater pollution pose risks to drinking-water supplies for nearby residents?

There is some concern among environmental groups and a few residents that groundwater contamination could come in contact with drinking water wells in rural areas, but more research is needed to determine this. Ameren Missouri has installed off-site groundwater wells near its Labadie and Rush Island power plants. According to the company’s water-quality manager, Craig Giesmann, the tests conducted have not shown a risk to drinking-water supplies. However, the company has not actually tested any residential wells.

The state is working on its proposal for new coal ash waste regulations. What would the Missouri Department of Natural Resources require utility companies to do?

The state’s plan, which became available on the state’s register earlier this month, would require utility companies to test groundwater near active coal ash ponds and landfills twice a year. Companies must test first for a short list of chemicals that include boron and sulfate. If there are excessive levels of contaminants detected on the short list, they then test for a longer list of chemicals on the long list, which includes arsenic, lithium and mercury.

If tests show a chemical on the long list exceeds standards, then the company must take action to clean up the contamination. The Missouri DNR could force a utility that planned to close a pond without removing the waste to dig up the waste from the pit, said Chris Nagel, solid-waste director for the state agency.


Will state regulations be strong enough to protect human health and the environment?

Utility groups, regulators and environmentalists disagree about whether Missouri’s proposal will be strong enough to address polluted groundwater. Utility groups support the plan and want to see it approved as soon as possible.

Wash U lawyer Maxine Lipeles, who represents the Missouri Sierra Club and the Labadie Enviromental Organization, wants to see several changes to the state regulations. She argues that utility companies should test four times a year to account for seasonal changes. She also notes that the state’s plan would weaken its regulation for coal ash landfills, since the proposed rule would mandate companies to test first for a short list of chemicals as opposed to the longer list they use now for testing.

Why are utility companies closing all of the coal ash ponds in Missouri?

Ameren officials say the utility is closing the ponds its power plants are converting to dry ash-handling systems. Coal ash-handling technologies have advanced so that power plants no longer need to use water to process them. Since facilities wouldn’t have wet ash under the dry ash-handling system, power plants don’t need to store the waste in ponds.

However, the federal coal ash rule requires coal ash ponds to meet specific requirements regarding their locations to prevent potential damage to the environment. If the ponds fail to meet one of these requirements, the company must close them. These requirements include not building in wetlands, areas where there’s known seismic activities and building at least five feet above the aquifer that’s closest to the surface. Ponds belonging to Ameren Missouri, Empire Utilities, AECI and other utilities failed the last requirement.

Follow Eli on Twitter: @StoriesByEli

Send questions and comments about this story to feedback@stlpublicradio.org


Eli is the science and environment reporter at St. Louis Public Radio.

Send questions and comments about this story to feedback@stlpublicradio.org.