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Duke University scientist unveils potentially damning new research on coal ash

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Crews deliver ash to a fully lined on-site landfill at Duke Energy's L.V. Sutton coal plant in North Carolina in July 2017.
Source: Duke Energy Corp.

A leading coal ash expert on Oct. 2 highlighted new research that could complicate a Trump administration proposal that critics argue would allow unlimited amounts of the material to be spread over the ground for structural fill projects.

The new findings show that coal ash produces hexavalent chromium, a cancer-causing chemical, when it interacts with fresh water to create a liquid known as leachate, said Avner Vengosh, a professor at Duke University's Nicholas School of the Environment.

Hexavalent chromium is notably the same cancer-causing chemical at the heart of a $333 million lawsuit involving Pacific Gas and Electric Co., a legal saga later adapted into the 2000 feature film "Erin Brockovich." Vengosh's yet-to-be-published study is the first to document the widespread presence of hexavalent chromium in coal ash leachate, according to Duke. Some lab-tested samples used in Vengosh's study contained levels of hexavalent chromium four times higher than the limit considered safe by the EPA.

Vengosh, whose research has also focused on the massive coal ash spill in 2008 at the Tennessee Valley Authority's Kingston station, presented his results at a public hearing for a U.S. Environmental Protection Agency proposal that would ease Obama-era coal ash regulations.

Those regulations, established under the EPA's Coal Combustion Residuals, or CCR, rule, were developed in the wake of the TVA spill and eventually finalized in 2015. Among many other requirements, the Obama-era rule requires an environmental review of any fill project that involves placing unencapsulated CCR on the land in amounts greater than 12,400 tons in nonroadway applications.

The 12,400-ton threshold was originally intended to represent the capacity of the smallest CCR landfill in the U.S., which the EPA calculated during the rulemaking phase using two different databases. After the CCR rule was finalized, however, industry commenters informed the EPA that the 12,400-ton threshold was a mistake resulting from some of the data being entered in cubic yards instead of cubic feet.

In August 2018, the U.S. Court of Appeals for the District of Columbia Circuit granted a request from the Trump administration to reconsider two provisions of the CCR rule concerning the so-called "beneficial use" of coal ash as recycled material. As a result, the EPA in July proposed to replace the 12,400-ton threshold with location-based criteria drawn from the existing CCR rule's criteria for disposal units such as coal ash ponds and landfills.

Those regulations require stored coal ash to be located a certain distance from the uppermost aquifer and wetlands. The existing rule's requirements also prohibit coal ash placement in an unstable area, flood plain, and within certain distances of a fault area or seismic zone.

'Unlimited quantities'

In Oct. 2 comments on the July proposal, American Coal Ash Association Executive Director Thomas Adams asserted that thresholds in the CCR rule and state regulations "have no underlying evidentiary support."

"Limitations are being imposed absent damage and absent science," Adams insisted, noting that the group's data shows that more than 180 million tons of CCR material have been placed in structural fills since 1980.

Going even further than the EPA's proposal, Adams argued that both the 12,400-ton threshold and location restrictions should be scrapped because requirements for fill projects are already addressed in a different part of the existing CCR rule. Subjecting fill projects to the same location restrictions as coal ash ponds and landfills "would mean that any beneficial use in contact with the ground outside a roadway would require a demonstration before one pound of CCR could be placed," Adams said.

However, Vengosh contended in his comments that the proposed revisions would allow the placement of "unlimited quantities of CCRs in the environment," potentially contaminating nearby drinking water wells, water bodies, and residences without any restrictions or safeguards.

Asserting his research raises new implications for the EPA's proposed changes, Vengosh added in an Oct. 2 interview that he wanted to share his findings before the full study is published so they can be included in the public record.

"The reason I'm coming here is to tell [the EPA] ... coal ash should not in any way be placed into the environment," the professor said.

Written comments on the EPA proposal are due Oct. 15.