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Duke Scientists Find More Coal Ash Hazards 'Under the Rug'

Current water quality monitoring looks only at the surface, according to Avner Vengosh, Duke professor of geochemistry and water quality.

  • Dec 06, 2010

As the U.S. Environmental Protection Agency weighs whether to define coal ash as hazardous waste, a Duke University study identifies new monitoring protocols and insights that can help investigators more accurately measure and predict the ecological impacts of coal ash contaminants.

“The take-away lesson is we need to change how and where we look for coal ash contaminants,” says Avner Vengosh, professor of geochemistry and water quality at Duke’s Nicholas School of the Environment. “Risks to water quality and aquatic life don’t end with surface water contamination, but much of our current monitoring does.”

The study, published online in the peer-reviewed journal Environmental Science & Technology, documents contaminant levels in aquatic ecosystems over an 18-month period following a massive coal sludge spill in 2008 at a Tennessee Valley Authority power plant in Kingston, Tenn.

By analyzing more than 220 water samples collected over the 18-month period, the Duke team found that high concentrations of arsenic from the TVA coal ash remained in pore water ─ water trapped within river-bottom sediment ─ long after contaminant levels in surface waters dropped back below safe thresholds. Samples extracted from 10 centimeters to half a meter below the surface of sediment in downstream rivers contained arsenic levels of up to 2,000 parts per billion ─ well above the EPA’s thresholds of 10 parts per billion for safe drinking water, and 150 parts per billion for protection of aquatic life.

“It’s like cleaning your house,” Vengosh says of the finding. “Everything may look clean, but if you look under the rugs, that’s where you find the dirt.”

The potential impacts of pore water contamination extend far beyond the river bottom, he explains, because “this is where the biological food chain begins, so any bioaccumulation of toxins will start here.”

The research team, which included two graduate students from Duke’s Nicholas School of the Environment and Pratt School of Engineering, also found that acidity and the loss or gain of oxygen in water play key roles in controlling how arsenic, selenium, and other coal ash contaminants leach into the environment. Knowing this will help scientists better predict the fate and migration of contaminants derived from coal ash residues, particularly those stored in holding ponds and landfills, as well as any potential leakage into lakes, rivers, and other aquatic systems.

The deadline for public comment to the EPA on defining ash as hazardous waste was Nov. 19; a final ruling ─ what Vengosh calls “a defining moment” ─ is expected in coming months.

“At more than 3.7 million cubic meters, the scope of the TVA spill is unprecedented, but similar processes are taking place in holding ponds, landfills, and other coal ash storage facilities across the nation,” he says. “As long as coal ash isn’t regulated as hazardous waste, there is no way to prevent discharges of contaminants from these facilities and protect the environment.”

Laura Ruhl, a Ph.D. student in Vengosh’s lab, is lead author of the study, which was funded by the National Science Foundation. Vengosh is corresponding author. Coauthors are Gary S. Dwyer, senior research scientist; Heileen Hsu-Kim, assistant professor of environmental engineering; and Amrika Deonarine, a Ph.D. student in Hsu-Kim’s lab.

Comments

Mon, Dec 20, 2010 energyski

Repectfully, Dr. Goodwin, your commentary says regulating coal ash as hazardous waste is not justified, but your comments themselves actually argue for it. There are two proposals for regulation of coal-ash waste on the table, one designating it as hazardous waste under subtitle C of RCRA, with the attendant federal mandates for how such toxic material should be handled. The other under subtitle D, with a more hands-off approach that is not mandatory and essentially delegates regulation of coal-ash waste to the states. You argue for mandatory engineering guidelines. That will only happen with the proposal for strong and enforceable federal regulations. Furthermore, you point to the TVA spill as a result of engineering judgment being ignored. Chances are extremely high that there will be further such engineering failures under a hands-off approach considering that there are several thousands ponds, landfills and ash heaps scattered across the nation. Companies cut corners, designs are not followed, unforeseen risks are not accounted for. Accidents can, do and will happen again. I notice that you do not deny -- because you cannot -- that coal ash comprises a menu of toxic ingredients, and that many of these react and migrate in contact with water. Instead, you base your argument on a hazardous waste designation inhibiting the beneficial re-use of coal ash in products such as dry wall -- and not directly, but only through the "potential risk of litigation by end users." If that's your rationale, the exact same argument applies to the many communities who live near coal-ash waste sites nationwide. Every consideration should be given to the "potential risk" of their groundwater being contaminated, which has happened already at least 130 times. The only way to keep the potential risk of further accidents happening and threatening groundwater supplies and more importantly public health, is for strong and enforceable federal regulations. Once those are in place, then the engineering approach you advocate for can be applied.

Wed, Dec 15, 2010 Don Neeley Indianapolis

Excuse me Shad, what data are you using to say 90% of US lakes and streams are contaminanted? This article is dealing with one locality after a single specific catastrophic failure. This data is not easily transferred to other uses/storage of coal ash. This story merely shows that inadequate investigation is being performed with regard to this case.

Mon, Dec 13, 2010 shad williams

That is not the point of the study, especially when over 90% of the lakes in streams in the U.S are contaminated AND the cost avoidance from coal ash discharge into the environment is substantially unregulated and not internalized.

Tue, Dec 7, 2010 Richard W. Goodwin West Palm Beach FL

Regulating Coal Ash as Hazardous Based on the Kingston Ash Spill in my opinion is not justified. The cause of the spill was due to TVA’s ignoring their geotechnical consultants concern regarding the structural stability of the pond’s dike wall. Over the past year the USEPA has investigated about 50 Coal Combustion Residue Impoundments – making recommendations to respective electric utilities retrofitting where required. Thus, a data base of engineering criteria exists to develop mandatory guidelines for future impoundments – preventing another dike wall failure. The Hazardous Waste Designation would greatly inhibit the beneficial use of Coal Combustion Residues e.g. FGD By-Product Gypsum and Fly Ash used as additive to construction material – due to potential risk of litigation liability by end-users.
The Kingston Ash Spill occurred because engineering judgment was ignored – applying an engineering approach to future facilities would not only avoid another accident but continue to use useful Coal Combustion By-Products based on demonstrated engineering applications.
Dr. Richard W. Goodwin, P.E.

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