The failure of a TVA coal-ash dam in Tennessee last December caused a huge mess, and prompted renewed attention on regulation of coal-ash handling and disposal.

Earlier today, the U.S. Governmental Accountability Office issued a new report updating Congress on efforts by the Environmental Protection Agency to start regulating the handling and disposal of toxic ash from coal-fired power plants.

The report is available on the GAO Web site, and here’s a brief summary of the findings:

— The exact number of surface impoundments at utility coal fired power plants is not known. However, EPA is currently undertaking an effort to identify the number and location of all surface impoundments in the United States and, as of September 14, 2009, had identified over 580 surface impoundments nationwide.

— Problems that have been identified with the storage of coal ash include potential structural defects and other risks of collapse of the surface impoundment, such as at TVA Kingston Facility; health and environmental risks from CCR storage due to potential leaching of contaminants into surface or groundwater from unlined or failed liners at surface impoundments, landfills, or sand and gravel pits; and potential risks from the discharge of wastewater containing CCR into surface waters from surface impoundments. EPA is currently analyzing the structural hazards and environmental risks associated with surface impoundments.

— EPA does not directly regulate CCR disposal in surface impoundments or landfills to prevent releases or a catastrophic spill, and states have a variety of regulatory controls on surface impoundments. EPA is developing proposed regulations but, as part of this effort, needs to address issues of federal and state roles for control and enforcement.

Lisa Evans, the coal ash expert over at Earthjustice, pointed out to me that the GAO report says:

“EPA has more recently stated it is also considering another hybrid approach whereby wet CCRs (in surface impoundments) would be regulated as hazardous wastes and dry CCRs (in landfills) would be regulated as non-hazardous wastes.”

Evans, who has been studying coal ash for years and pushing hard for tougher regulation of the stuff, had this to say about that:

This hybrid approach solves only half the problem.  Dry disposal of coal ash presents significant risks to health and the environment– it would be a big mistake for EPA to leave landfilling entirely to the states.  Current state laws are inadequate, and they will likely remain inadequate without EPA’s hazardous designation.