A pair of 80-foot-high earthen dams, one of them built in the Eisenhower era, stand between Charlotte’s water supply and more than 5 billion pounds of coal ash.
Duke Energy promises the dikes at its retired Riverbend power plant on Mountain Island Lake are safe. The latest detailed inspection, ordered by the Environmental Protection Agency after a huge ash spill in Tennessee in 2008, deems them “satisfactory.”
But it’s hard for the public, or even state inspectors, to learn much beyond that. Clouded by protective legislation, company secrecy and security concerns, the paper trail about Duke’s ash ponds is a foggy path.
The drabbest of byproducts, coal ash took on new importance after a failed dike smothered two rivers and 300 acres in eastern Tennessee five years ago. Environmentalists sprang into action, demanding that regulators rein in a massive, lightly policed and potentially toxic waste.
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Duke’s 39,000-ton ash spill into the Dan River a month ago set off a new round of scrutiny. A federal grand jury is investigating. State officials, themselves under pressure, are weighing what to do about ash ponds scattered at 14 Duke sites statewide.
Duke won’t release its internal assessments of the dikes. “We’re not going to elaborate beyond what’s in the public space,” said spokeswoman Erin Culbert.
North Carolina legislators, meanwhile, limited the amount of information about the dikes that’s available to state dam safety officials.
Reacting to the Tennessee spill, lawmakers ordered the state dam-safety office to take over ash pond inspections in 2010. The legislators deemed all the ponds to have state approval at that point. They also said utilities didn’t have to provide documents to continue operating them.
State officials did not know that stormwater pipes ran under the ash ponds on the Dan River until one of them broke Feb. 2.
The two ponds at Riverbend have four times the capacity of those on the Dan. They help make Charlotte an epicenter of ash.
Riverbend’s are among 45 ash-pond dams the EPA classifies as “high hazard” for their damage potential if they fail. Duke owns 12 of those dams in North Carolina, four of them in the Charlotte region. High-hazard dams also sit at the Allen power plant on Lake Wylie and Marshall plant on Lake Norman.
The saving grace on the Dan was that the closest drinking water user, Danville, was 25 miles downstream of the spill. The city of 43,000 has been able to filter ash out of its water.
On Mountain Island Lake, Charlotte-Mecklenburg Utilities’ main water source, the intake sits three miles downstream of Riverbend. CMUD serves 800,000 people.
Mecklenburg County’s water-quality chief has said an ash spill into Mountain Island would be “catastrophic.”
The Charlotte City Council asked staff last week for more information on Riverbend’s ash, including what Duke will do with the 2.7 million tons of ash stored there. The power plant closed last April.
“We’re just interested in understanding what the plan might be,” said environment committee Chairman John Autry. “How do we clean it up? When do we clean it up?
“I don’t want a spill. I don’t want any seepage.”
The 2009 inspection report recommends stability analyses and other studies of the Riverbend dikes that Duke says it has completed.
“The Riverbend dams remain safe and are routinely investigated by a number of professionals both inside and outside the company,” Culbert said. “We’re taking another look at ash basins across the fleet and will work through these issues with all the stakeholders involved.”
The EPA has access to all of Duke’s records on its ash ponds, she said.
The EPA-ordered report, and recent state inspections, note seepage from a secondary ash dam at the power plant. The Catawba Riverkeeper Foundation has detected metals above state standards in seeps around the plant. State dam officials say seepage is normal and appears to pose no structural risks.
Internal erosion from seepage causes about 20 percent of dam failures, says the Association of State Dam Safety Officials. The association counted 173 dam failures and 587 “incidents” that could have caused failures between 2005 and mid-2013.
Riverbend had operated since 1929, apparently without a dike failure. But environmental advocates say ash ponds, like nuclear power plants, pose low-probability but high-consequence risks.
The 2008 Tennessee Valley Authority spill will cost up to $1.2 billion to clean up. One scientist has estimated it will cost at least $70 million to repair the Dan River.
The dike that separates the two ash ponds at Riverbend was built on sluiced ash, similar to the construction blamed in the TVA spill, said Richard Gaskins, the engineer-turned-lawyer who heads the Catawba Riverkeeper Foundation.
“It’s always the unexpected thing that causes the problem,” Gaskins said. “Nobody thought about drainage pipes until this (Dan River) thing happened. The next one, it’ll probably be something we haven’t thought about.”
It’s hard to know what’s inside old dams such as Riverbend’s. Some were documented only in photographs as they were built.
“Some are not engineered. It’s basically a hole in the ground and you’re forming a containment system,” said Mohammed Gabr, a civil engineering professor at N.C. State University.
The legislation that put ash ponds under the state dam-safety office in 2010 said Duke and Progress Energy, then separate companies, weren’t required to supply the backup documents they did have, such as construction drawings and emergency action plans.
“That’s a bit of a hindrance,” said state dam-safety engineer Steve McEvoy. “It might have been nice to have plans.”
The utilities, citing the legislation, have refused to provide some information the state sought, he said.
Duke’s 23 active and 14 inactive ash ponds are among the 1,184 high-hazard dams the dam-safety office oversees. Nineteen staff members oversee a total of about 3,600 dams.
The office found six ash ponds with “deficiencies” needing repair the first time they were inspected in 2010. None have been cited since then.
Inspectors spend 90 minutes to two hours looking over an ash pond dike. Inspections are required, but most get annual checks. Following a checklist, they note animal burrows, overgrown vegetation, signs of erosion, obstructions and seepage from the dams.
The inspectors also look for signs of internal erosion such as muddy seepage or “boils” of water bubbling up near the dam. Gabr, the N.C. State professor, said experienced inspectors should be able to detect seepage that’s likely to become a problem.
“The key, in my opinion, is consistent observation to establish a baseline that can tell you when it’s getting bigger,” he said.
But the state inspections are purely visual. They can’t look inside the dams.
“This letter carries no implication regarding the internal stability of the dam,” state officials wrote after the most recent inspection of Riverbend’s dams in late 2012.
Duke’s adversary on coal ash, the Southern Environmental Law Center, is itching to get inside the records and heads of utility executives. So far that hasn’t happened.
“Where they have been in violation (of environmental standards) for years, it’s not something a utility executive wants to be questioned about,” senior attorney Frank Holleman said. “It’s not the highlight of a career.”
The law center’s threats to sue Duke last year prodded North Carolina’s environmental agency to file its own lawsuits over ash contamination.
That produced a proposed settlement over Riverbend and a second power plant that, if approved, would have let Duke avoid removing the ash from its ponds.
The law center found far more success when it filed notice it would sue two South Carolina utilities on similar grounds.
South Carolina’s environmental agency, unlike North Carolina’s, did not file its own lawsuits. The law center sued S.C. Electric & Gas and, separately, state-owned Santee Cooper.
Both utilities agreed in the past two years to remove ash from their ponds near waterways. That’s also the law center’s goal in North Carolina.
The N.C. Department of Environment and Natural Resources’ lawsuits, aimed at all 14 of Duke’s coal-fired power plants in the state, are based on groundwater contamination and tainted seepage flowing to rivers and lakes.
The Catawba Riverkeeper Foundation, one of the groups the law center represents, was allowed to join the state lawsuits over the three Charlotte-area plants.
The state and Duke proposed a settlement of the litigation over Riverbend and Duke’s Asheville plant. It called for a $99,000 fine and continued assessment of contamination.
Holleman views that deal as part of a state strategy to punish only the weakest violations by Duke, not those with more severe penalties.
DENR withdrew the proposal after the Dan River spill. But last week the department said it might be put back on the table this month – or expanded to include other Duke power plants.
An April 4 hearing is scheduled on the law center’s request for Duke’s internal risk assessments and other documents about Riverbend. DENR never sought Duke’s internal records, Holleman said.
“They just relied on what Duke told them,” he said.
The Catawba Riverkeeper Foundation, meanwhile, has also filed its own federal action over Riverbend.
A magistrate judge has recommended that it be dismissed. But if the case goes forward, Holleman said, the law center will again demand company documents and try to question executives under oath.
Sara Behnke, who lives on Mountain Island Lake, is a cancer survivor and a founder of the community group We Love Mountain Island Lake. She worries about whether pollutants from Riverbend, her neighbor across the lake for 14 years, will someday haunt her two children.
But her overwhelming worry is “definitely the idea of a catastrophic failure,” Behnke said. “I feel like we are at much greater risk of that than they would like to let on.”
The water utilities that rely on the lake take a calculated view of Riverbend’s ash stockpile.
In contrast to the relatively small Dan River, said Charlotte-Mecklenburg Utilities director Barry Gullet, Mountain Island Lake covers 3,281 acres. Unlike the free-flowing Dan, he said, Duke’s dams control the flow of water – and contaminants – into and out of the lake.
Gullet won’t detail the department’s emergency plans for responding to water contamination but said they don’t focus specifically on Riverbend. Lake Norman is a backup water source but supplies only about 20 percent of the county’s needs.
“There are a lot of things in this river basin that are potential water supply issues,” Gullet said. “So it’s hard to say that one’s a bigger risk or bigger threat than another because you don’t know the failure mode, you don’t know how it can be contained, you don’t know how quickly you’ll detect it.”
Gastonia’s intake on the lake is just downstream of Charlotte-Mecklenburg’s. The city has up to 10 days’ water supply in its Rankin Lake and could also turn to the South Fork Catawba River, its old source, in a pinch.
Like Charlotte, Gastonia is eager to see Duke’s plan for closing the Riverbend ash ponds, Assistant City Manager Flip Bombardier said. The city hasn’t taken a position on whether Duke should remove the ash, he said.
“But if it’s a hazard that could impact your raw water,” Bombardier said, “we would like to see that potential hazard minimized to the greatest degree possible.”