Coal news and updates

The first full of day of cleaning up a 2,500-ton coal ash deposit near the Schoolfield Dam began Monday.

Jeff Brooks, spokesman for Duke Energy, said the dredging process is on track to end in late June, with Abreu-Grogan Park — which is closed to the public during the process — set to re-open in July. The removed coal ash will be taken to Upper Piedmont’s dry landfill in Person County, North Carolina, and stored there permanently, Brooks said.

Duke contractor Phillips and Jordan of Knoxville, Tennessee, is performing the project.

The deposit at Schoolfield Dam measures about 350 yards long by 20 yards wide, and about a foot deep. Dredging began Friday afternoon, with Monday the first full day of the clean-up.

About 39,000 tons of coal ash spilled into the Dan River on Feb. 2 when a drainpipe failed at Duke’s old Dan River Steam Station in Eden, North Carolina. The spill coated the river bottom with toxic sludge for about 75 miles.

Brooks led a media tour of the dredging site’s staging area at the park on a sunny and hot Monday morning.

The accumulated coal ash at the dam is the largest deposit Duke has found that is a candidate for removal, Brooks said. He detailed the complex process involved in vacuuming the coal ash, sediment and water from the Dan River, before the water is separated and returned to the river.

“We’re trying to be minimally invasive,” he said of the operation.

Dredging up the coal ash involves several pieces of machinery, including the dredge in the Dan River that removes the mixture from the river bottom like a vacuum.

From the dredge, the coal ash, water and sediment travel through a pipe to a total clean station at the staging area. The station removes large debris and sand, which are conveyed to roll-off containers for disposal to the landfill.

Turbid water is sent to a clarifier tank, which provides settling capacity for fine sediments before clean water is sent back to the river.

Settled coal ash and sediment from the clarifier tank are routed to mix tanks, which are used for polymer mixing and flow equalization before they’re sent to belt presses.

The presses dewater fine sediments and clean water is routed back to the clarifier tank. Solids are sent via conveyor belt to roll-off containers to be taken to the landfill.

The contractor is using turbidity barriers, also known as “silt barriers” or “silt curtains,” to control the coal ash while it is being pulled from the river bottom.

Officials anticipate moving several dozen tons of coal ash per day from the site to the landfill in Person County.

The dredging system used for the Dan River Restoration Project in Danville is capable of dredging up about 1,500 gallons of coal ash, water and sediment per minute, Brooks said.

Shannon Todd, Duke Energy’s director of environmental services, said up to 100 tons of coal ash — over the course of eight to 10 trips — would be taken to the landfill per day.

An additional 253 tons of coal ash were caught by the city’s water treatment process.

Duke is also finalizing plans to clean up a 40-ton coal ash deposit at Town Creek, about two miles downstream of the Dan River Station.

Clean-up has not begun but that project is supposed to be complete around the same time the Schoolfield project is expected to end, Brooks said.

Danville’s water treatment plant will work around the coal ash removal behind Schoolfield Dam.

Barry Dunkley, Danville Utilities’ division director for water and wastewater treatment, said the plant will close its water intake valve during the daytime when dredging is taking place, and open up in the evening and operate overnight when there is no dredging.

Water Treatment Manager Alan Johnson said the city will take samples of water, including raw water around the intake and treated water leaving the facility. A sample will also be taken at the intake during dredging, Johnson said.

If the water is found to be safe, the treatment plant may return to daytime operations or continue its nighttime operation during the dredging project.

 

 

Source: http://www.roanoke.com/