The mine was in the middle of moving the longwall equipment to a new district when the elevated gas levels were detected. The longwall equipment is currently isolated from the affected area by permanent and temporary seals while nitrogen, foam and water are being pumped into the affected area.

Mine Safety and Health Administration (MSHA) and West Elk personnel are working together at the mine to determine when it will be safe to re-enter. When the remaining longwall equipment has been recovered, the old district where the elevated gas levels were detected will be sealed.

“Our first priority will be to ensure that the mine is safe for re-entry," said John W. Eaves, Arch's executive vice president and chief operating officer.

"Once that is accomplished, we expect the longwall move to be completed in a safe and efficient manner."

The mine outage is not expected to be very long and because of the planned longwall move, West Elk was already shipping coal from surface stocks.