Expert Report

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Burning coal in electric utility plants produces, in addition to power, residues that contain constituents that may be harmful to the environment. The management of large volumes of coal combustion residues (CCRs) is a challenge for utilities, because they must either place the CCRs in landfills, surface impoundments, or mines, or find alternative uses for the material. This study focuses on the placement of CCRs in active and abandoned coal mines. The report explains that placement of CCRs in mines as part of the reclamation process may be a viable option for the disposal of this material as long as the placement is properly planned and carried out in a manner that avoids significant adverse environmental and health impacts. This report discusses a variety of steps that are involved in planning and managing the use of CCRs as minefills, including an integrated process of CCR characterization and site characterization, management and engineering design of placement activities, and design and implementation of monitoring to reduce the risk of contamination moving from the mine site to the ambient environment. Enforceable federal standards are needed for the disposal of CCRs in minefills to ensure that states have adequate, explicit authority and that they implement minimum safeguards.

Key Messages

  • Although SMCRA does not specifically regulate CCR placement at mine sites, its scope is broad enough to encompass such regulation during reclamation activities.
  • Placement of CCR in mines as part of coal mine reclamation may be an appropriate option for the disposal of this material. In such situations, however, an integrated process of CCR characterization, site characterization, management and engineering design of placement activities, and design and implementation of monitoring is required to reduce the risk of contamination moving from the mine site to the ambient environment.
  • Putting CCRs in coal mines as part of the reclamation process is a viable management option as long as (1) CCR placement is properly planned and is carried out in a manner that avoids significant adverse environmental and health impacts and (2) the regulatory process for issuing permits includes clear provisions for public involvement.
  • The number of monitoring wells, the spatial coverage of wells, and the duration of monitoring at CCR minefills are generally insufficient to accurately assess the migration of contaminants.
  • The presence of high contaminant levels in many CCR leachates may create human health and ecological concerns at or near some mine sites over the long term.
  • There are insufficient data on the contamination of water supplies by placement of CCRs in coal mines, making human risk assessments difficult.
  • While SMCRA and its implementing regulations indirectly establish performance standards that could be used to regulate the manner in which CCRs may be placed in coal mines, neither the statute nor those rules explicitly address regulation of the use or placement of CCRs, and some states have expressed concern that they do not have the authority to impose performance standards specific to CCRs.
  • With regard to CCR placement in minefills, the committee concludes that while potential advantages should not be ignored, the full characterization of possible risks should not be cut short in the name of beneficial use.
  • landfilling, and minefilling), comparatively little is known about the potential for mine filling to degrade the quality of groundwater and/or surface waters particularly over longer time periods.