Dive Brief:

• Twenty four of Duke Energy's 26 coal ash basins across the Carolinas violate federal rules for the disposal of the hazardous generation byproduct, according to filings from the utility released Nov. 7.

• Nearly all of the disposal basins violated rules that require the bottom of coal ash pits to be five feet above groundwater aquifers and stipulate there can be no connection between aquifer and disposal facility. The sites were examined Sept. 28.

• The only two ash pits found to be compliant with federal rules have been fully excavated, a costly disposal technique Duke has resisted for many of its facilities. Among the basins found not compliant are those at the H.F. Lee and L.V. Sutton coal plants, which spilled coal ash into nearby waterways during Hurricane Florence in September. 

Dive Insight:

Duke's multiple violations of the Obama Administration's Coal Combustion Residuals (CCR) rule in North and South Carolina illustrate how many utilities are still struggling to deal with the toxic legacy of coal ash.

Coal ash is a byproduct of power generation that contains a number of materials known to cause human health problems, like mercury and lead. The September inspections are mandated for all utilities that still have ash basins under the federal CCR rules.

Outside engineers assessing the facilities found nearly all the basins did not meet the provisions of one or more CCR requirements, including locational restrictions, wetlands requirements and seismic impact zone requirements.

Twenty four of 26 basins across 14 plant sites also violated a section of the federal CCR regulations that requires the bottom of a coal ash storage unit be at least five feet "above the upper limit of the uppermost aquifer" and disallows any hydraulic connection between the base of the unit and the aquifer. 

The utility is required under North Carolina law to close down every basin deemed "high risk" by the end of 2019 and all basins by 2029. That can either mean fully excavating the sites, as it has done with its Asheville and Rogers basins, or lining the pits with clay and capping them, a cheaper alternative it favors for most facilities. 

Environmentalists say the compliance tests show that capping disposal facilities in place can still present risks to groundwater and communities that use it. 

"Those filings confirm not only is the coal ash too close, but it's connected to the groundwater, which of course means its pollutants [are] making it into the groundwater at every site," Frank Holleman, a senior attorney at the Southern Environmental Law Center, told Utility Dive. "Now we have on the record, in writing, official confirmation by Duke Energy's own engineers that Duke Energy has been violating the minimum national standards set out in the coal combustion rules everywhere it stores coal ash in North Carolina, except where it has completely removed ash from the pits."

Duke officials, however, said the test results support their plans to keep much of their ash in place. 

"What Hurricane Florence reminded the industry is that in circumstances where both capping and excavation are similarly protective of people and the environment, capping in place is the more responsible choice since that work can be completed in a matter of years, versus the decades that would be required for excavation of the largest ash basins," Duke Energy spokesperson Bill Norton told Utility Dive via email. "The considerably longer closure horizon required by excavation would unnecessarily increase vulnerability to extreme weather events."

Two of Duke's coal ash sites were breached during Hurricane Florence earlier this year. A dam breach at the L.V. Sutton plant leaked coal ash into the nearby Sutton Lake, which was inundated with floodwater that overflowed into the nearby Cape Fear River.

Coal ash was also found in the Neuse River near the utility's H.F. Lee plant, though there was contention among the utility, the state and local waterkeepers over the level of pollution at those sites and the methods of testing.

Both of the two basins at the L.V. Sutton plant were found to be not compliant with four different federal CCR requirements: the uppermost aquifer requirement, wetlands impact, seismic impact zone and unstable area requirements.

The wetlands violation indicates that "a number of sites the facilities are leaking in a way that's harmful to wetlands in the state," Holleman said. The utility will be required to stop putting bottom ash in lagoons that are not compliant with wetlands requirements within six months.

The stability and seismic impact zone requirements indicate that the sites are structurally unstable and aren't built to withstand earthquakes that could potentially occur in the areas they were built. Both the L.V. Sutton basins were found noncompliant with those regulations as well as the Weatherspoon plant's basin. 

While Duke will still face state regulations on coal ash, the status of the federal CCR rule is in limbo. This July, the EPA announced plans to replace it with a less stringent regulation, but that move is in conflict with a recent ruling from the D.C. Circuit Court of Appeals, which held that the original CCR rule was not protective enough of public health. 

The final status of the CCR rule is likely to be worked out in court. Below is a chart and map of the ash basins and their respective plants.