The third-largest coal ash spill in US history released up to 39,000 tonnes of coal ash and about 27 million gallons (102 million litres) of coal ash slurry into the Dan River in February 2014.

Duke said in its Q4 2014 earnings statement on February 18 it expected a proposed agreement could be reached and filed in “the next several days” for consideration by the court.

If approved, the proposed agreement would resolve the ongoing grand jury investigation of the company’s coal ash basin management.

Reported results for the fourth quarter 2014 include a charge of about $100 million, or $0.14 per share, related to the company’s assessment of probable financial exposure related to any agreement.

This charge has been excluded from the company’s adjusted diluted earnings per share results for 2014, which president and CEO Lynn Good described as “a year of great accomplishment and challenge”

“We believe we are close to an agreement that, if approved by the court, would resolve the US government’s ongoing grand jury investigation into the February 2014 Dan River coal ash spill and ash basin operations at other North Carolina coal plants,” Good said.

However, even if Duke does resolve the issue, it still faces North Carolina Department of Environment and Natural Resources charges and others by activist groups for potentially violating state laws by contaminating groundwater.

In a statement issued to the Charlotte Observer, the DENR said the settlement “would not resolve [the department’s] civil litigation over violations at coal ash ponds, which is ongoing”

“We also continue to investigate violations of state groundwater standards and to maintain our enforcement partnership with the US Environmental Protection Agency for civil violations of the Clean Water Act,” the DENR said.

North Carolina, however, is doing itself few favours in the eyes of environmentalists with its legislation that allows companies to choose to either plug leaks or seek to have them included in wastewater discharge permits that the department itself issues.

Duke and the department are going ahead with the second option.

“Duke has been openly leaking for years. Now they’re asking DENR to give them amnesty,” senior attorney Frank Holleman of the Southern Environmental Law Centre, which is planning a lawsuit to fight the permit plan, told the Observer.

“Can you imagine us allowing any municipality or county in the state to permit a wastewater treatment plant that leaks in multiple ways?”

Duke announced 2014 full year adjusted diluted earnings per share of $US4.55 last year compared to $4.36 the year before.