When a pipe under a North Carolina coal ash pond burst on February 2, the effect was devastating. Coal combustion waste containing heavy metals and other carcinogenic compounds contaminated the Dan River 70 miles downstream of the spill.
The river supplies drinking water to communities in North Carolina and Virginia. As of yet, drinking water appears to be safe.
A great deal of guesswork has gone into estimating the amount of coal ash that was released during the disaster. But using images obtained from unmanned mapping aircraft, researchers at Wake Forest University created a 3D model of the spill, and produced a more accurate, independent assessment of the spill.
"We think we have a precise estimate of the ash and water slurry that flowed out of the pond based on our methodology," WFU biology professor Miles Silman told the university news service. "The uncertainty comes from the amount of water that continued to drain from the ash, which is a question for hydrologists”
“Our work provides an independent estimate of the spill.”
Between 16 and 20 million gallons of ash-laden water spilled from the pond on Feb. 2, with up to 15 million gallons released on subsequent days, according to the researchers.
The North Carolina Department of Environment and Natural Resources (DENR) experienced hostility from the administration of the recently-elected Republican governor, according to a report by the New York Times. Federal prosecutors have begun a criminal investigation into the spill and the relations between Duke Energy, which owned the ash pond, and DENR regulators.
"Current and former state regulators said the watchdog agency, once among the most aggressive in the Southeast, has been transformed under Gov. Pat McCrory into a weak sentry that plays down science, has abandoned its regulatory role and suffers from politicized decision-making," the Times wrote.
The scrutiny placed on the state's regulators highlight the importance of independently verifying government data as it pertains to environmental regulation and disaster mitigation. If WFU research is any indication, aerial robots and drones seem well-suited for this task.
Journalists should observe their research as a case study into how news organizations and independent journalists also could verify claims with unmanned aircraft.
Below is a simulated "fly-over" of the spill site, generated with imagery gathered by the WFU researchers.