Source:A panoramic view of the Belews Creek ash pond and work being done to strengthen its earthen dam.
While the North Carolina Department of Environmental Quality (DEQ) reviews public comments on its preliminary classification of the Belews Creek ash impoundments as low-to-intermediate risk, officials at Duke Energy described what could happen to the facility based on the final classification.
If the facility if ultimately deemed as a low-risk facility then the company would likely drain the existing ash pond and cap it in place, according to Duke spokeswoman Zenica Chatman.
“If we cap it in place we will have to remove all the water from the basin,” she said. “That process is called de-watering and that would likely happen in two phases. First we would remove all of the water that you see, called free water. That water would go out through the current permitted outfall of the plant. We would put it out through the existing discharges and would be lowering it about a foot per week.”
She said the company would be monitoring the discharges to make sure they did not exceed their permitted levels of contaminant discharges during that process.
Once the standing water is removed the company would have to remove the remaining water which saturates the ash.
“We would have to build an on-site treatment facility to treat that water before it is returned to the land,” said Chatman.
After all the ash had been dried out, Chatman said Duke would then fill the impoundment with dirt to create a shape which would provide areas for runoff and then cover it with a synthetic liner material to keep water, from rainfall, from peculating through the coal ash and back into the ground water.
“Think of it as coffee grounds in a filter,” said Chatman. “If you do not add water you don’t get coffee. The synthetic filter would not allow any water to get into the ash.”
She said the initial synthetic covering would then be covered over with a second filtration device.
“This has a synthetic filter on each side with a geo-net core that will transmit any water that infiltrated form the soil cap to the geo-net to where ever the stormwater run off area would be,” said Chatman. “They have used this technology many, many times when they close landfills.”
Chatman said Duke would do whatever science dictated needed to be done to the site to ensure minimal impact to the ground water in the area.
“All of our decisions on basin closures are based on a set of guiding principles,” she said. “Those principals include ensuring continued safety and stability of material for the long-term, ensuring any closure remains effective during storms and flooding, ensuring groundwater impacts are effectively addressed, when excavation is required, leveraging ash recycling, on-site landfills and consolidated storage to minimize community impact, complying with the N.C. Coal Ash Management Act and federal Coal combustion Residual regulations, and seeking solutions that address environmental impacts and balance stakeholder interests.”
A December 2015 Corrective Action Plan, prepared for Duke Energy by HDR Engineering and submitted by Duke to the DEQ, notes that a cap in place scenario would likely still involve the outflow of a number of contaminates from the site.
“Under the Cap-In-Place scenario, modeled concentrations of boron and chloride at the selected well locations decrease below their respective 2L Standards quickly (i.e. within 15 years),” reads the report. “The other COI modeled concentrations increase initially and then decrease over the 250-year simulation period. The modeled concentrations of arsenic, chromium, hexavalent chromium, cobalt and thalium remained above their respective 2L Standards, IMACS, or NC DHHS HSL throughout the 250-year simulation period. At the end of 100 years in the Cap-In-Place scenario, chromium, cobalt, and thallium were estimated by the model to be above the 2L Standard or IMACs at the compliance boundary north of the ash basin dam. “
What would excavation look like?
If the DEQ decides to rank the Belews Creek facility as an intermediate or high risk ash impoundment then Duke Energy would be required to excavate the ash from its existing impoundment.
“We want to minimize the impact to the community if we have to excavate, so we would look to see if we could build an on-site landfill,” said Chatman. “If we have to move it off site we would look at how much we could move by rail as opposed to trucking.”
She said the company was currently excavating other ash sites using both rail and trucking, noting that rail provides the most effective way of moving the ash.
She said trucks at those operations are carefully lined with a tarp like material and secured and washed before leaving the site to prevent any unintended distribution of ash while in transit. Each site is different, she said, but train cars also are either lined or securely capped before leaving an excavation site.
Duke’s Dan River Site Communicator Jeff Brooks said using rail transport to excavate a site dramatically increases the speed at which the job can be accomplished.
“Each truck can carry about 18 tons of ash,” he explained. “At 10 trucks a day you are looking at 180 tons a day that you can move. At the Dan River site we run 60 car trains and each car can carry over 100 tons, so each train is carrying at least 6,000 tons of coal ash up to three times a week. You are looking at the potential of taking 18,000 tons of coal ash per week versus maybe 1,000 tons by truck.”
If Duke were forced to excavate the Belews Creek facility to an off-site location, Brooks said it could take decades to do so, even with most efficient rail system possible.
“We can carry about a million tons off of a site each year using our rail system,” he said. “That is about the maximum we can achieve. We have about 20 million tons here at Belews Creek. If you had to excavate it would be a phenomenal challenge given the scope and scale of the operations here.”
Jimmy Fylth, Duke’s Belews Creek spokesman, said the issue was further complicated given the fact that Belews Creek was still an active plant.
“The sites where we have been using rail so far are all closed,” he said. “We get two train cars of coal a day that we have to unload. Trying to use those same rail-lines to excavate, I don’t know if it is physically possible.”
Brooks said at other operations Duke has had to build up to 5-miles of additional on-site rail line to provide parking space for all of the rail cars being used.
“Then you have to build load out pads and different processing areas,” he said. “It is not like you can roll it up to what you have here. A whole infrastructure has to be built to support the rail operations and that is at a retired plant where you are not competing with rail space for coal coming in and the other activities. It would be a significant challenge.”
Chatman said if the site is classified as high risk, which would require excavation by the end of 2019, the company would do its best to meet the requirements of the law.
“We are working to close these basins as quickly as we can and as safely as we can even with out a high risk classification,” she said. “But there are specific issues at Belews Cree that would have to be taken into consideration. Belews is a functioning, operational coal fired facility so we have to transition to a dry bottom ash handling system before would be able to close the ash impoundment.”
She said that transition alone could take the company until sometime in 2019 to complete.
“We would do our best to comply with the law, but we would have some very big challenges here at Belews,” she added. “If you look at the volume of a site like Belews it could take decades to excavate all of the material if that is what the law says we should do.”
The December CAP indicated that excavation would result in most contaminants dropping under the 2L Standards over a 250-year time period, with boron, chloride, beryllium and thallium dropping below levels with in 10 years and other contaminants like arsenic and cobalt dropping below the levels near the end of the 250-simulation period.
Current repairs ongoing
Chatman said Duke currently has over 20 people working each day to repair and reinforce the main dam at the plant’s coal ash pond.
“Basically it is blanket of sand and stone that we are putting on the main dam,” she explained. “When we are done with it, it will add an extra layer of stability to the dam.”
The new material is being added at the toe of the existing dam with the intention to further limit seeps, not just for contaminants, but of structural fill dirt from the earthen dam.
“If you do not have a natural filter or a geo-synthetic filter what will tend to happen is you will lose soil with the seepage,” she said. “So we are putting the sand and rip-rap up against the area where seepage might emerge from and creating a graded filter. We are ensuring that the dam does not lose soil though seepage over time. We are putting a heavy weight at the toe and then it will be further weighted with top soil and vegetation to hold it in place. That keeps it stable.”
Nicholas Elmes may be reached at 336-591-8191 or on Twitter @NicholasElmes.