Source: http://www.news-record.com, May 3, 2014
By: Taft Wireback
Three months after the disastrous Dan River spill, experts say its potentially harmful coal ash is on the move in some places and burrowing into the muck in others.
They say both routes could pose long-term threats to the environment, stemming from the Feb. 2 spill at Duke Energy’s retired coal-fired plant in Eden.
The U.S. Environmental Protection Agency, Duke Energy and other members of a task force cleaning up the spill have found only a limited number of submerged coal ash deposits along the 70 miles of affected river, said Ken Rhame, an on-scene coordinator for the EPA who is monitoring the Dan River cleanup.
Rhame did not want to make an off-the-cuff estimate of how many such clumps they have tallied, but he said Friday evening that it was fewer than 25, including three relatively large ones that have been approved for dredging,
The rest of the huge spill apparently remains either suspended in the water as it migrates downstream or has settled into the river bed and surrounding areas in smaller concentrations.
“What we think has happened is that it’s commingling with a lot of the other suspended particulates that are in the river system,” Rhame said. “We’re finding some areas where it already has been covered by sediments. You may have a layer of coal ash that you find at a depth of 4 inches under the sediment.”
The good news is that so far, the Dan seems to have evaded or at least minimized the most immediate, dire consequences that river watchers had feared after a drainage pipe broke underneath a basin full of the toxic ash.
The U.S. Fish and Wildlife Service says that as part of the task force, its agents have been on the river almost daily but have documented no direct link between the spill and the deaths of any creatures. That doesn’t necessarily prove no such deaths occurred, but it is encouraging, a spokeswoman said.
Repeated tests of surface water up and down the river show it meets acceptable standards and has returned to pre-spill quality levels, though North Carolina health officials still maintain advisories against eating fish and shellfish taken downstream of the plant and against swimming or other “recreational contact” with the Dan in that same segment of the river.
Big sweep
Duke Energy plans to begin vacuum dredging the largest single deposit of coal ash from the spill, a clump 1,000 feet long and 60 feet wide near a hydroelectric dam in Danville, Va., about 20 miles downstream from the spill.
That effort should start sometime this week, although preparations were slowed by recent heavy rains, Duke Energy spokesman Jeff Brooks said. The utility has apologized for the spill and promised to clean up the Dan at its own expense under the supervision of federal and state regulators.
The spill left behind a mixed bag of conditions, not the continuous coating of coal ash that some people might envision, Brooks said.
“As you can imagine, the Dan is a powerful and dynamic river,” he said. “As such, the material has been dispersed along the river in varying degrees.
“In some areas, we don’t find any coal ash at all. In others, a very thin deposit (lies) on top of or mixed in with the sediment. In some places, there are deposits of coal ash that are now covered over by sediment as part of the river’s natural circulation cycle.”
Duke Energy dredged up and safely disposed of a deposit much smaller than the one in Danville about two months ago. That deposit was located in Eden near the drainage pipe that ruptured at the shuttered Dan River Steam Station to cause the third largest coal-ash spill in U.S. history.
A large deposit farther downstream near Town Creek in Rockingham County will be dredged up and taken to a landfill in tandem with the Danville cleanup, officials say.
Removal work can’t get underway again soon enough, said Brian Williams, program manager with the nonprofit Dan River Basin Association advocacy group.
“It’s in the sediment. It’s moving with the sediment. It’s moving downstream,” Williams said of the coal ash. “When the river is 6 feet up and rolling red, that sediment is being picked up off the bottom and moved downstream.”
Whisked away
When he thinks of the Danville deposit — an estimated 2,500 tons near Schoolfield Dam — Williams recalls a huge “sand bar” of coal ash that appeared just downstream from the spill at the Eden plant right after the release.
That sand bar of coal ash is long gone now, but not because anybody cleaned it up, Williams said.
“It was tons and tons of coal ash,” he said. “The reason it’s gone now is because the river is dynamic. As it floods, it keeps pushing the ash downstream.”
In the days immediately after the spill, Duke Energy pegged the lost ash at 50,000 to 82,000 tons based on its own rough estimates. The gray waste comes from coal burnt to make electricity and it was stored underwater in a large, riverside basin with the doomed drainage pipe running beneath.
But a “third-party” engineering firm later lowered the estimate of missing ash after an in-depth study put the more likely amount at 30,000 to 39,000 tons, according to the EPA.
Either way, it’s a heck of a lot. And a substantial amount will never be retrieved from the river.
“You’re not going to recover 100 percent of the spill,” Rhame said.
The EPA coordinator said his agency, Duke Energy and other members of the cleanup team are examining each of the clumps of coal ash they have found downstream to decide whether it makes sense to remove them or whether a removal effort would create more pollution at that specific location than it would prevent. In addition to officials from Duke Energy and the EPA, the task force brings together members of several federal and state agencies, including both North Carolina and Virginia environmental departments.
“We are continuing to take samples at all locations to determine if the ash is accumulating, moving, being buried or being uncovered,” said Brooks of Duke Energy, adding that technicians are “modeling” the river in studies that aim to predict where it might take the ash.
Such modeling is difficult to do because every river is different and scientists lack in-depth data about the Dan and its makeup, said Avner Vengosh, a professor of geochemistry and water quality in the Nicholas School of the Environment at Duke University.
Bound for Kerr?
Generally, coal ash behaves “much like any other sediment in the river,” Vengosh said.
Some of it will settle out of the water in deposits at the river’s bends and in other deeper, slower areas, such as the pool behind the Danville dam. Another unknown amount will work its way more or less permanently into the riverbed, he and other experts said.
Scientists say it makes sense that the heaviest
concentrations would be closer to the plant in the early going. But the general trend likely will see large amounts of ash migrating toward the mouth of Kerr Reservoir about 70 miles downstream, some predict.
“Once ash reaches Kerr Reservoir in significant amounts, which it will, exposure and toxicity to fish and wildlife in this ash deposition zone could be highly significant,” said Dennis Lemly, a Wake Forest University biology professor and U.S. Forest Service scientist.
Along the way, ash will continue to settle out in small clumps or “pockets” in the Dan’s slower eddies, where rocks and other obstacles disrupt the river current, Lemly said.
“That’s what makes it so dangerous to fish and wildlife,” he said. “Those same (eddies) are where fish and wildlife congregate, feed and reproduce.”
When storms such as those that hit the Piedmont Triad last week disturb the river bottom, the settled ash could re-emerge in fresh bursts of pollution.
“If there are fish living there, suddenly you have a cloud of ash, and once again you have a problem,” Vengosh said.
The main threat stems from heavy metals and other ingredients in the coal ash, particularly selenium, known to damage various species’ ability to reproduce, said Lemly, who has devoted much of his career to studying how coal ash affects fish and other aquatic creatures.
Over the years, Lemly linked the ash and similar coal by-products to genetic deformities of the eyes, gills, spine and other body parts in fish, in addition to infertility.
“Time frame is important,” Lemly said. “It could take decades for this ash to fully move down river, if it ever does.”