Numerical Simulations of Spilled Coal Ash in the Dan River and the Environmental Impact of the Incident

Coal ash is the second largest industrial waste in the US with approximately 130 million t produced per year.Only about 45% of the coal ash is recycled. The remaining amount of coal ash waste is stored in containment cells and ponds, which are generally located at the proximity of rivers and other surface water resources. Accidental release of coal ash and associated toxic chemicals into water resources due to failure of containment structures may pollute the environment and harm the aquatic ecosystem. Numerical modeling can be a useful tool to predict the movement of the coal ash and associated chemicals in surface flows for mitigation, incident response and recovery efforts. This paper presents the two-dimensional modeling of the accidental spill of coal ash into the Dan River, NC, on February 2, 2014, using hydrodynamic, sediment transport and pollutant transport modules of the CCHE2D software developed at the National Center for Computational Hydroscience and Engineering, The University of Mississippi. The transport and fate of coal ash and the two associated contaminants, arsenic and selenium, during the first 32 days after the spill were modeled over a 24.2 mi-long (38.9 km) reach of the Dan River extending immediately upstream of the spill site to the Schoolfield Dam in Virginia. The simulations revealed what happened physically and chemically in the river channel immediately after the incident in the river channel. The results were validated using available data and field observations.