Environmental officials in North Carolina say their tests show that coal ash released from Duke Energy’s Sutton power plant in Wilmington during flooding from Hurricane Florence has not had a negative impact on the Cape Fear River.

The state’s Department of Environmental Quality (DEQ) on October 4 said its test results on water samples collected on four different days following the hurricane aligned with results from Duke Energy’s water tests. Environmentalists, though, said the state tests are not conclusive because they did not include tests on the sediment at the bottom of the river.

The DEQ said heavy metals found in the river water are within state standards. Paige Sheehan, a Duke Energy spokeswoman, in a statement said the state’s test results show “that Cape Fear River quality is not harmed by Sutton plant operations.” A DEQ spokeswoman said the state did find slightly elevated levels of copper in the river, but said they are not a threat to public health.

Two environmental groups—Waterkeeper Alliance and Earthjustice—on October 3 said they had measured “insanely toxic” levels of contamination near the Wilmington power plant. The groups said their tests showed arsenic levels 71 times higher than North Carolina’s drinking water standard.

Duke Energy in a statement called the group’s findings an “outrageous claim.”

Peter Harrison, a spokesman for Earthjustice, an environmental advocacy group that said it collected its own samples from the river, in an email to media said “it would be reckless to claim that there have been no impacts to the lake and river, no ongoing threat, and no release of coal ash, without thoroughly evaluating the sediment” at the bottom of the river.

The Sutton plant today is a 625-MW natural gas combined cycle plant that came online in 2013. The site previously was home to a three-unit, 575-MW coal-fired plant that was retired in 2013 and has since been demolished. The site is home, though, to dumps storing coal ash, which is residue left behind after coal is burned. The coal ash contains heavy metals including lead, arsenic, and mercury. Duke Energy has been excavating millions of tons of ash from the old waste dumps at the Sutton site and moving it to a lined landfill.

Duke Energy on September 15 said that heavy rains from Florence, which dropped about 30 inches of rain on the Wilmington, caused floodwaters that breached several points in the earthen dam at Sutton Lake, the plant’s 1,100-acre reservoir. The utility said it estimates about 2,000 cubic yards of coal ash and dirt were displaced from a coal ash landfill during Hurricane Florence, with some of the ash flowing into the river.

Frank Holleman, a senior attorney with the Southern Environmental Law Center, in a statement after the spill at Sutton said, “This spill illustrates the dangers of Duke Energy’s practice of disposing of coal ash near waterways throughout North and South Carolina. Disposing of coal ash close to waterways is hazardous, and Duke Energy compounds the problem by leaving most of its ash in primitive unlined pits filled with water.” Holleman later said, “When a hurricane like Florence hits, we have to hope and pray that our communities do not suffer the consequences of years of irresponsible coal ash practices by the coal ash utilities.”

Duke in February of this year, in its annual financial report to the Securities and Exchange Commission, said it had resolved a series of legal actions stemming from a coal ash spill into the Dan River in North Carolina in February 2014. North Carolina enacted the nation’s first comprehensive coal ash management law in September 2014 in response to the accident at Duke’s coal plant in Eden, North Caroline, which spilled up to 39,000 tons of coal ash into the Dan River.

North Carolina regulators earlier this year said Duke could pass most of the costs of cleaning up the utility’s coal ash operations to ratepayers, though the state Utilities Commission assessed a $30 million “mismanagement penalty” on the company. Duke had said it would seek more than $240 million from customers to upgrade its coal ash management system to meet new state and federal regulations.

Duke has said it will close all of its coal ash storage dumps by 2029. 

—Darrell Proctor is a POWER associate editor (@DarrellProctor1, @POWERmagazine).