What can utilities learn from the recent coal ash spill in North Carolina?

Representatives from Duke Energy recently announced that a leak stemming from a retired coal-fired plant may have dumped anywhere between 50,000 and 82,000 tons of coal ash into North Carolina's Dan River, located 130 miles northeast of Charlotte.

According to reports by the Charlotte Observer, the leak appears to have originated from a broken 48-inch stormwater pipe located beneath the unlined ash pond at the plant. The 27-acre pond has a capacity of approximately 155 million gallons, though in this particular incidence inspectors say the level has been much lower since the plant was retired in 2012.

Coal ash is toxic in large quantities, as it contains numerous harmful materials. These include arsenic, mercury, lead and other heavy metals. Though it is not known exactly how much ash is in the water, observers near the site told the news source that they saw ash along the banks of the Dan River, and that the water had a gray tint. As a result, officials have been notifying communities downstream from the incident, such as Danville, Virginia, located only six miles away

Local officials say that, so far, water quality has not been affected there.

"All water leaving our treatment facility has met public health standards. We do not anticipate any problems going forward in treating the water we draw from the Dan River," Barry Dunkley, division director of water and wastewater treatment for Danville Utilities, told the Associated Press.

Meanwhile, representatives from the North Carolina Department of Environment and Natural Resources have tested the water, but have not drawn any conclusions about what it might contain, according to the Charlotte Observer. 

It is still unclear as to why the pipe failed in the first place. The news source reported that independent engineers from the U.S. Environmental Protection Agency investigated the pond in 2009, specifically focusing on the dam that held in the water and coal ash. They reportedly found it to be in good condition, though they did find some seepage emanating from the more than 50-year-old structure.

For its part, Duke Energy seems interested in closing down old coal-fired power plants and improving its environmental performance overall. The company has retired seven of the 14 coal plants located in North Carolina and writes on its website that it wishes to "focus on environmental and economic sustainability." Since the Dan River plant has unlined ash ponds that have led to groundwater contamination, the utility has been considering ways to close the ponds at these sites and resolve related environmental liabilities. Utilities in other states have done the same.

As stakeholders seek to prevent similar events from occurring in the future, they may wish to work with environmental consultants who have experience preparing for the worst situations and responding accordingly when liabilities are uncovered.