Under the Resource Conservation and Recovery Act (RCRA), the legislation under which EPA regulates solid and hazardous waste, EPA is conducting a study of coal combustion waste (CCW). This paper focuses on the placement of CCW in or on land from which minerals have been or are being extracted (i.e., backfilled into mined areas), a practice also known as minefilling. Mine placement of CCW may occur in surface or underground coal mines or in sand and gravel pits or other types of mines. The use of CCW for minefilling is a recent but rapidly growing practice. Commercial electric power producers (e.g., electric utilities) are currently the only known generators of CCW that is minefilled. Minefilling may be practiced either for disposal purposes as an alternative to disposal in a landfill or surface impoundment, or can be practiced in ways that take advantage of certain beneficial properties of the waste (e.g., controlled placement of alkaline coal ash in the acidic environment of an abandoned coal mine to assist in neutralizing acid mine drainage).

EPA is engaged in information collection to fill information needs on minefill practices and controls. EPA's goals are to ensure that minefilling is practiced in an environmentally protective manner, and to identify best management practices for minefilling. The mines in which CCW is placed may have direct hydraulic connection with underground sources of drinking water and with surface waters. As explained in the May 2000 Regulatory Determination on CCW, EPA's primary concerns involve direct placement in ground water, acid leaching potential, and adequate monitoring. The Regulatory Determination also acknowledged EPA's lack of information on practices and controls for minefilling.

This paper will present EPA's concerns and perspectives on CCW minefill issues, including the status of EPA's information gathering activities regarding minefill management practices and controls.

*Disclaimer: This paper presents the opinion of the author and does not necessarily reflect the views of the Agency.