Coal Ash Conundrum

What happens to the river ecosystem when tons of coal ash gets mixed into the layer of sediment on the river bottom? (Pete Harrison/Waterkeeper Alliance.)

QUEST North Carolina’s Daniel Lane contributed to this article.

On a Sunday in February in Eden, North Carolina, a sinkhole formed in the middle of a pond of coal ash slurry next to the retired Dan River Steam Station. A stormwater pipe underneath the ash pond cracked and was sucking in ash and shuttling it to the nearby river. Duke Energy, owner of the facility, sent emergency crews to the site, but it was a complicated fix. By the time they got it securely sealed on Thursday, the 48-inch pipe had belched more than 39,000 tons of coal ash into the Dan.

The Dan, a major tributary of one of the largest and least disturbed ecosystems on the East Coast, ran gray. From Danville, Virginia, whose 42,000 residents draw their water from the river, to Kerr Lake, home to seven recreation areas with 800 miles of trails, a gray ribbon of coal ash was visible along 70 miles of prime sport-fishing territory.

Coal ash can have 24 times the concentration of selenium compared to native soil. Click to enlarge. Courtesy: EPA

What Is Coal Ash?
Coal ash is a byproduct of burning coal to make electricity. For every nine million tons of coal burned in the U.S., approximately one ton of coal ash is produced. Coal ash is a highly concentrated source of the mineral content that is left after the carbon is burned. It is similar to soil in terms of grain size and texture but contains high concentrations of toxic elements like selenium and arsenic. Coal ash is typically stored wet behind earthen dams adjacent to the power plant. The security of these impoundments is currently under review. The EPA is assessing the hazard potential of the 676 impoundments around the country. As of March 2014, 52 surface impoundments were given a “high” hazard potential rating by the EPA, meaning a failure of the impoundment is “probable, one or more expected.”

Why This Matters
Water tests at the Danville water treatment plant showed a spike in arsenic in the first days of the contamination, but arsenic levels returned to normal a week later. The ash, however, was not gone. It was just gone from view, merged with the most fertile zone in a river — the nutrient-rich and life-giving layer of sediment.

Most species of aquatic insects live in the sediment, collecting, filtering, and grazing upon minute particles of food. Nothing goes to waste down there, not even the arsenic and selenium from coal ash. Heavy metals get lodged into the tissues of any insect that eats them. When minnows eat the insects, they consume the toxins. Larger fish get toxins from every minnow they eat. As you climb higher in the food chain, the amount of arsenic or selenium you find multiplies progressively. This process is called biomagnification and it has impacts on a food web from bottom to top.

Dr. Dennis Lemly, research fish biologist and professor of biology at Wake Forest University, calls selenium an “invisible” toxin because it doesn’t directly harm the fish that eats it. “Instead, it migrates to the ovaries and enters growing embryos, causing defects in major organs and physical deformities in the head, spine, mouth, and fins (see effects of selenium poisoning in North Carolina here). A lot of them die shortly after birth,” Lemly said. “So over a period of two or three years, the older fish die off and there’s no young ones to replace them and repopulate. They just die off.”

Location of coal ash contamination sites as of Feb, 2014. Red denotes a coal ash contaminated site. Green denotes a coal ash spill. Black denotes both a contaminated site and a spill. Source: EPA Coal Ash Damage Cases. Map courtesy Arc-GIS
Location of coal ash contamination sites as of Feb, 2014. Red denotes a coal ash contaminated site. Green denotes a coal ash spill. Black denotes both a contaminated site and a spill. Click to enlarge. Source: EPA Coal Ash Damage Cases. Map courtesy Arc-GIS

The Future of Coal Ash Disposal
While the long-term effects of the Dan River coal ash spill won’t be known for a while, the short-term effects may be influencing regulation. In 2008, the catastrophic 1.1 billion gallon spill in Kingston, Tennessee, galvanized public debate about coal ash storage. In 2010, the EPA proposed the nation’s first-ever rules to ensure the safe disposal of coal ash. According to the EPA, “these rules would ensure stronger oversight of the structural integrity of impoundments in order to prevent future accidents.”

Dr. Lemly is in favor of more regulation, “I have been on record many times recommending a complete banning of the surface disposal in impoundments. I continue to do that. I’m hopeful that the EPA ruling on coal ash that is supposed to come out in December will provide a complete ban on surface impoundment disposal.” The EPA is expected to finalize their rules for coal ash on December 19.

Coal Ash Conundrum 18 September,2015Lucy Laffitte

Author

Lucy Laffitte

Lucy B. Laffitte, PhD has been a science communicator and environmental educator for over thirty years. She has produced in-class and on-line instructional design, curriculum development, and certificate programs to a variety of conservation organizations, including the Oregon Museum of Natural History, Tall Timbers Research Station, North Carolina Museum of Natural Science, Salt River Project, New England Wildflower Society, Rachel Carson Institute, and Nicholas School of the Environment. She has published in print and on air—writing a nature column for The Cape Codder and was the founding radio producer for the environmental program the Allegheny Front. She has a bachelor’s degree in natural science, from the University of Oregon, a Master’s in adult education and graphic design and a PhD in environmental resources from North Carolina State University. She has been science education consultant for UNCTV working on QUEST and NC Science Now since April 2013.

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