A federal plan to use ash waste from coal-fired power plants to shore up some Mississippi River levees drew objections Thursday from environmentalists who are worried that toxins in the ash might seep into the river and public water systems it serves.
The Sierra Club and other nature groups lined up against the Army Corps of Engineers' plan, worrying during a public hearing that the use of coal or fly ash questionably could extend later to levees along other inland rivers and perpetuate coal burning, widely believed to contribute to global warming.
"If this should turn out to be toxic (after it's been injected into a levee's weak spots), how do we get it back out?" Tom Ball, a member of the Sierra Club and Missouri Stream Team, pressed during the 90-minute hearing that drew about 50 people, including electric utility representatives.
"This fly ash is hazardous waste, regardless of what you call it," added Catherine Edmiston, an environmentalist heading an Illinois group opposing longwall mining. "I am against putting it against a major river. I think we need to think about this."
Corps officials called the injection of a slurry of water, coal ash and lime into 25 miles of slide-prone levees in 200-mile stretch of the river from Alton, Ill., near St. Louis to southern Illinois' tip the cheapest, longest-lasting fix among several options it weighed.
Yet the corps pledged not to move hastily, calling any decision months away and pressing that the search for the cheapest fix for taxpayers won't trump public safety. For now, the corps says, the ash-slurry plan appears best.
"All alternatives will be fully evaluated," Gary Lowe, the corps' manager of the project. "This is a long process."
Various studies have suggested the ash -- long used in making roads and cement -- contains arsenic, selenium, mercury and other substances defined as hazardous, and may be closely linked to cancer.
The corps has said clay used to build the levees more than a half-century ago wasn't strong enough to last long-term, and its significant shrinkage at low moisture levels allows for the formation of cracks that filled with water from precipitation, weakening the embankment.
The proposed slurry involving fly ash would fill cracks and meld with substances in the clay, producing a cement-like, soil-fortifying material that locks in trace metals within the ash, corps engineers insisted Thursday.
The ash has been used on levees near Memphis since 1995, Lowe said. But corps officials pressed Thursday by some of the environmentalists said they were unaware of whether tests were ever done to see if any of heavy metals from the ash leached into the river there.
The corps said other options considered included replacing soil in the slide-prone sections with firmer ground trucked in, or mixing the dug-out soil with firming lime, then reinserting and compacting it. But such efforts were more expensive and time-consuming than the ash-slurry plan.
The corps could not specify when asked Thursday how much each option could cost; Lowe said the slurry plan could be "hundreds of millions of dollars" cheaper than some of the other alternatives.
Concerns about coal ash were revived in December 2008, when 5.4 million cubic yards of it breached an earthen dike and spilled into and around the Emory River from the Tennessee Valley Authority's Kingston plant near Knoxville. The TVA -- the nation's biggest public utility -- is in the midst of a projected $1.2 billion cleanup of the mess.
The Environmental Protection Agency in May first proposed federal regulation of coal ash, perhaps as a hazardous waste form. The plan would allow coal byproducts to be used in concrete, wallboard and other building materials.