Using Power Plant Waste to Solve Disposal Problems

During the past several months, following the Tennessee Valley Authority’s (TVA’s) ash and scrubber sludge spill in Tennessee, the public and media have used this incident to engage with elected officials and federal and state regulators. On December 22, 2008, an ash dike ruptured at an 84-acre coal waste containment area at the TVA’s Kingston Fossil Plant in Roane County, Tenn., releasing 1.1 billion gallons of coal fly ash slurry. It was the largest fly ash release in U.S. history.

In May 2009, the U.S. Environmental Protection Agency (EPA) signed an enforceable agreement with TVA to oversee the removal of coal fly ash slurry at the Kingston Fossil Fuel Plant. The cost of this clean-up is estimated at almost $1 billion. During Jan. 2009 Public Works Hearings, TVA CEO Tom Kilgore said that TVA had chosen to implement inexpensive patches instead of more extensive repairs of the holding ponds, admitting, "Obviously, that doesn’t look good for us."

The New York Times has advocated further regulation: "The lack of uniform regulation stems from the E.P.A.’s inaction on the issue, which it has been studying for 28 years." EPA Administrator Lisa Jackson promised, during her confirmation hearing, to promulgate stricter coal plant waste storage regulations. Capitalizing on the political opportunity of the TVA Kinston spill will escalate with continued congressional hearings. Elected and appointed officials will find the coal industry an easy and demonized target for more stringent regulations.

These incidents and consequences should not indict coal-fired power plants or the electric utility industry; unexpected costs from ten to hundreds of million dollars and public embarrassment are sufficient punishments. How to avoid such upsets should be the focus of coal-fired power plant operators specifically and the electric utility industry in general.

An engineering approach, reflecting demonstrated technology and recognizing coal combustion by-products’ (CCB’s) chemical and geotechnical properties, should be embraced by electric utilities with coal-fired power plants. Commitments to regulators to develop and implement this approach would curb excessive requirements. Electric utilities should capitalize upon the industry-wide knowledge and submit concepts and designs to the EPA as regulatory approaches are being developed.

If increased regulation translates into using CCBs in land disposal applications, with improved methods of placement (optimal compaction) and enhanced site management (capitalizing on the concrete-like behavior of coal combustion by-products), then such stronger regulation can be justified.

Consider the following research programs that would develop better uses of CCBs while improving how they are disposed of.

Retrofit surface impoundments to strengthen walls. The particle size of flue gas desulfurization residue and fly ash shows this blend could be used as a grout material to stabilize existing CCB surface impoundment dike walls. When used as grout, the blend must be able to penetrate between the interstitial soil spaces. Grouting existing soil dike walls would be about 90% less costly than slurry cutoff walls.

Improve landfill methodology. The inherent pozzolanic-like behavior of lime-laden CCBs enables achieving improved geo-technical properties such as strength and permeability. Achieving liner-like permeabilities, by capitalizing upon CCB’s inherent characteristics and applying proper placement control, achieves cost savings of 65% over traditional disposal methods such as synthetic liners.

Improve the design of landfill and surface impoundment embankments. Considering the inherent engineering properties of CCBs justifies using this material to form surface impoundment dike walls. Approximately 27.5 million tons of CCBs are retained in surface impoundments. A demonstration program, based on laboratory and bench-scale testing, would indicate industry’s willingness to address future requirements in a cost-effective manner.

The electric utility industry and its trade and research organizations are urged to commit to conducting such programs (demonstrating the application of CCBs in land disposal), thereby showing a good faith effort to cooperate with regulatory bodies and address recent CCB disposal problems.

[Editor’s note: See also the related story in this issue about recent developments concerning the TVA coal ash spill.]

—Dr. Richard W. Goodwin, PE ([email protected]) is an environmental engineering consultant based in West Palm Beach, Florida.

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