In November 1992, the U.S. Bureau of Mines, in cooperation with the Office of Surface Mining (OSM), used two recently-developed pneumatic backfilling devices to completely fill an abandoned coal mine haulage tunnel with 1/4 in. and 1 in. limestone. OSM had determined that this tunnel represented a potential danger to the community, as it is directly under several residential streets. OSM offered the site as a demonstration for the Pneumatic Pipefeeder and the High-Efficiency Ejector. The tunnel, 600 ft long, 14 ft wide and 7 ft high, was backfilled in 23 working days with about 2,400 tons of stone. The project demonstrated the usefulness of the two devices for abandoned mine remediation applications, as well as the potential for application in other industries.