Launch Slideshow

Image

The Fly Ash Threat

The Fly Ash Threat

  • Image

    http://www.theconcreteproducer.com/Images/tmp508%2Etmp_tcm77-1298123.jpg

    Image

    250

    An aerial image before the Kingston, Tenn., ash slide on Dec. 22, 2008.

  • Image

    http://www.theconcreteproducer.com/Images/tmp509%2Etmp_tcm77-1298125.jpg

    Image

    250

    On Dec. 30, 2008, the Emory River is inundated with coal ash slurry after a containment pond ruptured.

  • Image

    http://www.theconcreteproducer.com/Images/tmp50A%2Etmp_tcm77-1298129.jpg

    Image

    300

    Simple storage and loading would require new permitting and safety procedures if the EPA classifies fly ash as a hazardous material.

  • Image

    http://www.theconcreteproducer.com/Images/tmp50B%2Etmp_tcm77-1298132.jpg

    Image

    250

    A microscopic view of the controversial material.

View PCA's response to the fly ash designation issue, "Fly Ash in Concrete-Benefits of Use and Impacts of its Designation as a Hazardous Waste."

The concrete industry as we k know it may be changing in response to an event that happened on Dec. 22, 2008.

At a Tennessee Valley Authority (TVA) electric generating plant in Kingston, Tenn., one dike of a containment pond ruptured, spilling more than 5.4 million cubic yards of coal ash slurry. The Emory River was inundated and covered with more than 300 acres of wet fly ash. Cleanup is expected to cost more than $1 billion.

No one disputes this spill was a major engineering failure that led to a local environmental disaster. Four homes were destroyed and more than 20 were damaged. No one was injured and, despite dire predictions from environmental activists, water quality in the area did not significantly deteriorate. “All EPA, TDEC (Tennessee Department of Environment and Conservation), and TVA water treatment facility sampling results … continue to meet water quality standards for drinking water,” the TVA stated.

What is in dispute is what to do next. Spurred by cries of environmental activists to prevent such accidents, the long-term consequences of this accident, based more on politics than science, could change the way fly ash is used or disposed of in the U.S. for the foreseeable future. If fly ash is declared a hazardous waste, it is impossible to overstate the damage the concrete industry would suffer.

Disposal and beneficial use

The EPA considers fly ash a nonhazardous waste material under Subtitle D of the Resource Conservation and Recovery Act (RCRA). This means that individual states have jurisdiction over the material's storage and disposal. Environmental groups want this ruling changed so that fly ash is classified a Subtitle C hazardous wastes which would be regulated by the federal government.

This ruling has been true since 1980 under the so-called Bevill exclusion. This excludes “solid waste from the extraction, beneficiation, and processing of ores and minerals” from regulation as hazardous waste under Subtitle C of RCRA. In 2000, the EPA re-examined the situation.

Again it determined that coal combustion products (CCP, which includes fly ash, bottom ash, and flue-gas desulfurization material) were exempt to classification as a hazardous waste due to the desire to avoid placing “barriers on the beneficial uses of coal combustion waste so they can be used in applications that conserve natural resources and reduce disposal costs.”

The U.S. Energy Information Administration estimates that almost half of the electricity generated in the U.S. comes from coal, resulting in about 130 million tons of CCP. About 55%, or 72 million tons, is fly ash. About half the fly ash generated is currently used for beneficial purposes, mostly in concrete. This beneficial use not only saves landfill space but reduces the amount of cement being produced and thus the amount of CO2 being generated.

The fly ash that isn't used, though, ends up in landfills or containment ponds. To handle the excess ash, some electric utilities mix it with water and pump the slurry into containment ponds. Unfortunately, these ponds have not always been well designed or maintained, which is what led to the Tennessee disaster and the current dilemma.

The EPA doesn't trust the states to properly regulate fly ash but has no legal way to regulate it federally other than to designate the material as hazardous under Subtitle C. This distrust prompted EPA Administrator Lisa Jackson to pledge during her confirmation hearing last January to come up with new disposal regulations for CCPs by the end of 2009.

Unfortunately for the nation, Jackson's pledge may have created a greater environmental problem than she intended. And while EPA has for many years promoted using fly ash, even sponsoring the Coal Combustion Products Partnership (C2P2) to increase its beneficial use, it now appears that some sort of hazardous designation is likely.

Fly ash in concrete

Using fly ash as a cement replacement is perhaps the single greatest contributor to making concrete more environmentally friendly. Concrete's greatest environmental liability is the inclusion of portland cement, with its energy-intensive manufacturing process.

The typical equation cited by PCA is that about one ton of CO2 is released for every ton of cement manufactured. Using fly ash in a concrete mix reduces the amount of cement needed, thereby reducing the carbon footprint while consuming an industrial waste product rather than sending it to a landfill. The Electric Power Research Institute estimates that beneficial use of CCPs annually saves 159 trillion Btu, 32 billion gallons of water, 11 million tons of CO2 released to the atmosphere, and 51 million cubic yards of landfill space.