Numerical Modeling of the Fate and Transport of Contaminants Due to a Coal Ash Spill Accident in the Dan River

On February 2, 2014, the failure of a storm water pipe under the primary coal ash pond of the Dan River Steam Station owned by the Duke Energy released an estimated 39,000 t of coal ash and 27 million gal.of pond water into the Dan River near Eden, NC. Together with the coal ash, a number of contaminants absorbed on the particles and dissolved in the pond water were also released into Dan River.One dimension numerical model, CCHE1D, developed by the National Center for Computational Hydroscience and Engineering, the University of Mississippi, was used to simulate the fate and transport of contaminants in Dan River and Kerr Reservoir. The entire study reach extends from the USGS Wentworth gauge on Dan River, about 22 km upstream of the spill location to the Kerr Dam, about 182 km downstream of the spill location. Transport and fate simulations in the water column and in the bed were carried out for arsenic (As), and selenium (Se). Good agreements were obtained by comparing the simulation results with EPA’s field observations. The simulation results show that concentrations of those selected contaminants in water column and bed sediment are below the EPA screening values after five months of the spill accident. It is also found that most of the chemicals released to the river will eventually deposit in the bed of Dan River and Kerr Reservoir. The simulation results provide useful information for water environment evaluation and water resource management.