title: Characterization of metals released from coal fly ash during dredging at the Kingston ash recovery project.
abstract: A storage-pond dike failure occurred on December 22, 2008 at the Tennessee Valley Authority Kingston Fossil Plant resulting in the release of over 4million cubic meters (5million cubic yards) of fly ash. Approximately half of the released ash was deposited in the main channel of the Emory River, Tennessee, USA. Remediation efforts of the Emory River focused on hydraulic dredging, as well as mechanical excavation in targeted areas. However, agitation of the submerged fly ash during hydraulic dredging introduces river water into the fly ash material, which could promote dissolution and desorption of metals from the solid fly ash material. Furthermore, aeration of the dredge slurry could alter the redox state of metals in the fly ash material and thereby change their sorption, mobility, and toxicity properties. The research presented here focuses on the concentrations and speciation of metals during the fly ash recovery from the Emory River. Our results indicate that arsenite [As(III)] released from the fly ash material during dredging was slowly oxidized to arsenate [As(V)] in the slurry recovery system with subsequent removal through precipitation or sorption reactions with suspended fly ash material. Concentrations of other dissolved metals, including iron and manganese, also generally decreased in the ash recovery system prior to water discharge back to the river.
authors.affiliation: U.S. Army Engineer Research and Development Center, Environmental Laboratory, 3909 Halls Ferry Rd., Vicksburg, MS 39180, United States. Anthony.J.Bednar@usace.army.mil
authors.forename: A J
authors.initials: AJ
authors.lastname: Bednar
authors.forename: D E
authors.initials: DE
authors.lastname: Averett
authors.forename: J M
authors.initials: JM
authors.lastname: Seiter
authors.forename: B
authors.initials: B
authors.lastname: Lafferty
authors.forename: W T
authors.initials: WT
authors.lastname: Jones
authors.forename: C A
authors.initials: CA
authors.lastname: Hayes
authors.forename: M A
authors.initials: MA
authors.lastname: Chappell
authors.forename: J U
authors.initials: JU
authors.lastname: Clarke
authors.forename: J A
authors.initials: JA
authors.lastname: Steevens
mesh_terms: D003031:Coal; D060729:Coal Ash / Q000737:chemistry*; D008670:Metals / Q000737:chemistry*; D045483:Rivers / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D003031:Coal; D060729:Coal Ash; D008670:Metals; D014867:Water
keywords: Dredging; Fly ash; Metal release; Speciation