One year ago this month, a 48-inch metal storm pipe running beneath an impoundment of coal ash — the byproduct of coal-burning power plants — broke open, dumping an estimated 30,000-39,000 tons of ash and 27 million gallons of contaminated water into North Carolina's Dan River.
Duke Energy, which operates the impoundment and over 30 others in the state, will pay $100 million to settle a federal grand jury investigation into its coal ash management practices. The company still faces lawsuits from state regulators and environmental groups.
The Dan River accident was among the worst such spills in the nation's history and helped to push the issue to the forefront of environmental concerns. In part due to the Dan River spill, the US Environmental Protection Agency (EPA) revised federal regulations for storage of coal ash. Yet, a year after portions of the Dan River turned an ash-grey hue, environmentalists remain concerned about the risk of additional soil and water contamination from coal ash ponds.
Power plants generate 140 million tons of coal ash each year, which is stored in over 1,000 impoundments nationwide. According to Earthjustice, the nation's largest environmental law firm, at the time of the Dan River spill there were 208 documented cases of structural failure at coal ash impoundments, ranging from catastrophic breaches of retaining walls to slow leaks, which often go undetected for long periods of time.
As long as coal has been used to generate heat or electricity, there's been problems with the ash it generates, which contains lead, cadmium, mercury, and arsenic.
In the 19th century, coal ash rained down on those living nearby industrial facilities. Eventually, power companies began installing smokestacks, which trapped the ash before it took to the sky. But the plants still had to dispose of the ash they had captured. Often the ash was dumped into rivers and streams. By the 1950s, companies began disposing of their coal ash inlandfills and, after decades of pressure from environmental groups, began lining impoundments to better prevent soil and water contamination.
Despite the improvements in storage technology, coal ash spills and leaks remain a problem, said Lisa Evans, an Earthjustice attorney specializing in hazardous waste law.
"We generate or burn coal in almost every state," she told VICE News. "Every time you generate or burn coal you create ash."
Across the country, dozens of coal ash impoundments have failed, sometimes spectacularly like in Kingston, Tennessee in December 2008, when over one billion gallons of coal ash burst through an earthen wall, contaminating two tributaries of the Tennessee River and damaging several homes. Sometimes, however, coal ash contamination goes unnoticed by government agencies, slowly leaching into soil and nearby rivers and streams. Conservation groups tested water quality in North Carolina's Yadkin River, which runs along a Duke-owned coal ash pond. They found levels of carcinogens, such as cadmium, that were eight times those allowed for ground water and surface water.
Earthjustice has mapped coal ash contamination across the country. "It's almost like name a state," Evans told VICE News. "Without stringent requirements — and requirements really meant to solve the problem — you have utilities making really poor efforts at storing waste."
In December, the EPA rolled out new regulations aimed at preventing coal ash spills. New coal ash facilities will be required to install protective liners aimed at preventing leaching of coal ash into the soil and groundwater.
"Even though it was those high profile and catastrophic events, like the Dan River, that really drove the rule making, the resulting rule is not strong enough to have prevented one of those disasters," Harrison said.
The new regulations, complain many environmental groups, leave monitoring of existing, sometimes decades-old, facilities largely up to the companies that operate them. And, more fundamentally, the agency chose to regulate coal ash as a solid waste, rather than hazardous waste, which would have resulted in tighter restrictions.
Evans hopes forthcoming EPA rules on wastewater generated by coal-burning power plants, expected to appear in September, could help fill in some of the gaps left open by its December regulations.
"Coal ash needs to be seen as something that impacts the nation," Evans told VICE News. "It's a long festering problem that requires a national solution."
Back in the Dan River, though, most of the coal ash that leaked last year remains along the riverbed and little is know about what the long-term impacts of the contamination might have on the ecosystem and drinking water supplies.
Follow Kelsey Dayton on Twitter: @Kelsey_Dayton