GEOCHEMICAL INVESTIGATION OF POTENTIAL TOXIC METAL RELEASES FROM TVA COAL ASH SURFACE IMPOUNDMENTS INTO NEARBY RIVER WATERS AND SEDIMENTS

On December 22, 2008, approximately 5.4 million cubic yards of coal ash sludge spilled from a breached surface impoundment at the Tennessee Valley Authority (TVA) Kingston Fossil Plant, approximately 40 miles west of Knoxville on the banks of the Emory River. This research investigates geochemical evidence of prior release of coal ash from four TVA power plants which store coal ash on site: Paradise (KY), New Johnsonville (TN), Gallatin (TN), and Widows Creek (AL). Both upstream and downstream river sediment and river water samples were collected at each plant, as well as at two TVA coal-fired plants which do not store ash on site: Cumberland (TN) and Bull Run (TN). Concentrations of metals contained in coal ash, including As, Pb, Tl, Se, Hg, Ba, S and Cd, were measured in each sediment sample by x-ray fluorescence spectrometry. Concentrations of metals in each water sample were measured by inductively coupled plasma mass spectrometry. Additional data collected at each sampling site include water temperature, pH, conductivity, and total dissolved solids. Comparison of upstream to downstream metals concentrations at each plant, and comparison to metals concentrations in samples collected at the Kingston plant, show that although the geochemical signature of a coal ash spill similar to that at Kingston is identifiable by significant increases in downstream metals concentrations (notably As, Pb, Tl, Ba), a similar downstream geochemical signature is not present at any other plant. However, the data also suggest that plants which do not store coal ash are as likely to release metals into nearby waterways as those plants which do store coal ash on site. Notably, both the Bull Run and Paradise plants exhibit equally elevated concentrations of As, Tl, and S in downstream water samples, and elevated concentrations of Ba in downstream sediment samples. Also of note are elevated downstream Pb concentrations in sediments at all plants except Kingston and New Johnsonville. These findings suggest that although large-scale ash releases have not occurred at TVA plants included in the study, metals may be released from plant sources other than coal ash surface impoundments, or from other industrial activities in the vicinity of TVA plants.