Coal Ash in Spill Could Not Have Been Used in Concrete

The ash from the Tennessee Valley Authority’s (TVA) Kingston Fossil Plant that is now endangering the local community following a December 22 breach in a holding pond is most likely an 80/20 mix of fly ash (from smokestack pollution control systems) and bottom ash. To be used in concrete, fly ash must be low in residual carbon, as defined by ASTM Standard C 618. The boilers at the Kingston plant run at relatively low temperatures to reduce emissions of nitrogen oxides. A side effect of this lower temperature is that the coal is not burned as completely and the ash retains more carbon.

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