January 10, 2009
Tennessee coal ash disaster resonates in Montana By JO DEE BLACK and RICHARD ECKE Tribune Staff Writers
A national controversy over the disposal of coal ash from power plants has placed the spotlight on Montana, where a complex of older coal-fired power units at Colstrip was the subject of a multi-million-dollar court settlement.
In Tennessee and Alabama, ash spills have stirred controversy, prompting examinations of the handling of power-plant byproducts nationwide.
In May, owners of the Colstrip power plant in southeastern Montana Ñ a facility that stores more ash in ponds than any other power plant in the country Ñ agreed to pay $25 million to settle a lawsuit filed by 57 plant workers and nearby residents. The plant's ponds were blamed for contaminating water supplies in subdivisions and a trailer park.
Many of the ponds at the Colstrip power plant were in place before regulations were established. State environmental officials say the operator, PPL Montana, is working to fix leaks.
"There's been a tremendous amount of improvements to those ponds since they were first constructed and I'd argue that they have always been under regulation," said David Hoffman of PPL Montana. "Over the years, technology has advanced when it comes to pond construction. PPL and our predecessor, Montana Power Company, continually worked to stay ahead of the curve by incorporating that technology."
The units at Colstrip have ash ponds that are zero discharge, meaning all water and wet ash stays within the facility.
"Recently, we've implemented a paste system, where ash is slurried and carried to the ponds through a pipe, then it's made into a paste about the consistency of a thick milk shake," Hoffman said.
The paste is laid out on the ponds and allowed to dry to the consistency of concrete, he said.
"That way it seals the pond," Hoffman added.
Newer power plants, including those under construction such as the Highwood Generating Station east of Great Falls, tend to opt for dry handling of ash, said Jeffrey Chaffee, vice president of Bison Engineering Inc., a consultant on the Highwood project.
Chaffee said recently problems encountered in the eastern and southern United States are not likely to happen at the new Great Falls plant.
"There is one clear, major difference," Chaffee said. "They handled their ash wet, in other words, it was in ponds. The ash in Highwood will be handled dry. Generally, the newer technology has moved away from wet-ash handling."
Chaffee said ash created by burning coal at the Highwood plant will be moistened to keep dust down, but otherwise will be handled dry.
Work already has begun to excavate earth so that the ash can be buried on the Highwood power plant site 8 miles east of Great Falls. Chaffee said the design includes a clay liner and other precautions to keep ash in the vaults. He added that the ash will be encapsulated in the ground, rather than stored above a dam like the ponds that recently breached elsewhere. State officials approved the design, Chaffee said, noting it presents a "very, very minor" risk that the buried ash will pollute the area.
Richard Liebert, chairman of Citizens for Clean Energy, a group that opposes the plant, said members remain concerned about high winds blowing ash around, and are worried about the proposed liner.
"They say clay is good enough; it's impermeable," Liebert said, adding he is not convinced a clay liner offers sufficient protection from spills.