Framework for Assessing Closure of Coal Ash Ponds Goes Public

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May 31, 2016

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Framework for Assessing Closure of Coal Ash Ponds Goes Public

On May 16 the Relative Impact Framework for Evaluating Coal Combustion Residual Surface Impoundment Closure Options was published by the Electric Power Research Institute (EPRI)1. The Framework provides electric utilities and other stakeholders a comprehensive and science-based approach to assessing potential beneficial and adverse impacts to human health and the environment associated with closing a CCR surface impoundment. Gradient worked with EPRI to develop and refine the Framework and has applied the methodology to assess surface impoundment closure scenarios at several sites.

The Framework is needed now more than ever because in April 2015 the US Environmental Protection Agency published its Final Coal Combustion Residual (CCR) Disposal Rule. Among other deadlines in the CCR Rule, unlined surface impoundments at utilities that have stopped receiving CCR by October 2015 are exempt from the requirements of the Rule (including post-closure care and groundwater monitoring requirements) only if the impoundment is dewatered and closed by April 2018.

How a utility closes a CCR surface impoundment is a complex and costly decision that will involve a number of different stakeholders. While the Framework provides a flexible approach to assessing closure scenarios, it focuses on the following two options:

  1. Closure-in-Place, which involves leaving the CCR in the current surface impoundment and dewatering, backfilling, and capping the impoundment; or
  2. Closure-by-Removal, which involves dewatering the surface impoundment, excavating the CCR from the surface impoundment, transporting the material by truck to lined landfill cells, redisposing of the CCR in the landfill, and then closing the surface impoundment and landfill once the redisposal is complete.

The key “pathways” of exposure assessed in the Frameworkfor each closure scenario include:

  • groundwater and surface water quality (impacts to drinking water and ecological receptors);
  • air quality impacts from particulate matter emissions for workers and nearby residents;
  • worker and community safety (e.g., vehicle accidents associated with closure activities); and
  • green and sustainable remediation (GSR) metrics (e.g., emissions of air pollutants (CO2, SOx, NOx), energy consumption, water usage).

Because an assessment under the Framework can be tailored to the user’s needs, the Framework is useful for developing closure plans that minimize human health and environmental impacts, and it can be used to inform regulators and the public of the implications of each closure scenario.

If you have questions about the Framework and how it could be used to help inform your surface impoundment closure, please visit Gradient’s website or contact us.

For more information on Gradient’s services, please contact:

Andrew B. Bittner, M.Eng., P.E.
Principal Scientist


Ari S. Lewis, M.S.


Kurt Herman, M.Eng., P.G.


Christopher M. Long, Sc.D., DABT
Principal Scientist


Gradient is an environmental and risk sciences consulting firm renowned for our specialties in Toxicology, Epidemiology, Risk Assessment, Product Safety, Contaminant Fate and Transport, Industrial Hygiene, Geographic Information Systems, and Environmental/Forensic Chemistry. We employ sound science to assist national and global clients in resolving their complex problems relating to chemicals in the environment, in the workplace, and in consumer products.

1The Electric Power Research Institute conducts research and development relating to the generation, delivery and use of electricity for the benefit of the public. An independent, nonprofit organization, EPRI brings together scientists, engineers and experts from academia and the power industry to help address challenges in electricity.

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