Assessing the potential for downstream release of contaminated sediments associated with a recent fly ash spill

Appalachian State University, Boone NC

Investigators

Abstract

ABSTRACT This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). In the early morning of December 22, 2008, a breach in the retaining pond at Tennessee Valley Authority?s (TVA) Kingston Power Plant near Harriman, Tennessee, released about 4.13 million m3 of coal fly ash slurry, about 20% of which directly entered the Emory River. Within about 3.2 km the Emory River discharges into the Clinch River, which in turn flows into the Tennessee River after several kilometers. Our objects are to evaluate the downstream impacts of this fly ash spill with emphasis on: (1) spatial characterization of fly ash within the downstream river sediments and waters and changes with time; (2) characterization of the total and labile heavy metals in the fly ash in these sediments; (3) predictions of changes in changes in fly ash sediment transport and associated heavy metals; and (4) development of effective strategies for remediation in consultation with TVA. Given the background data TVA has collected on river bathymetry, will we conduct two surveys (one immediately and one about 4 months later following the hurricane season) with the Edge Tech 3100-P portable sub-bottom profiling system to estimate the amount of fly ash deposited on the bed of downstream reaches. Concurrent river bed sediment samples will be collected for particle size and heavy metals analysis. These data will provide the basis for dynamic sediment and geochemical budgets for the affected reaches of the river systems. To further extrapolate these data, we will conduct 3-D modeling that couples flow and sediment transport, including bedload, suspended load, and dissolved solids transport. As such, reasonable predictions of fly ash transported both as bedload and suspended sediment, along with associated heavy metals, can be obtained within the impacted reach of the Emory River and, if necessary, into the Clinch-Tennessee fluvial systems without making unnecessary assumptions about the hydraulics and geophysical/geochemical history of the system. Findings from this rapid response investigation will help guide rehabilitation efforts at the affected site and assist with priority setting of these efforts.