The National Institute for Occupational Safety and Health (NIOSH) with assistance from MSHA, conducted an extensive review of bulkhead permits submitted to MSHA's technical Support office in Bruceton, PA. This NIOSH Information Circular was developed for operations that need to construct an underground impoundment system, as well as for those that currently operate one. The information contained in this report is geared toward the permitting aspect. However information on monitoring and emergency response planning and training could be useful to operations that currently have underground impoundments.