US Mine Safety and Health Administration spokesperson Amy Louviere confirmed for ILN that the agency had modified the k-order at the operation near Billings to permit the 3 Right development section to resume mining.

“With this modification, mining is now ongoing in both the longwall and the development sections,” she said, adding that rehabilitation had started in the area of a roof fall that destroyed the overcast in the mains.

“The long-term modifications to the roof control plan are still being worked out to address higher cover areas that caused so much trouble on the current longwall. The development section has 2000 feet to mine before cover increases significantly.”

Signal Peak Energy president John DeMichiei told the Associated Press that crews had installed additional supports along one of the entries to prevent additional collapses.

Bull Mountain suffered a total of four roof falls in July and early August. While several MSHA citations for safety violations have been issued to the mine, penalties had not been assessed as of Thursday.

Following one of the falls in late July, a miner conducting repair work was injured, but later cleared to return to work according to mine officials. The unidentified worker, who was part of a crew sent in to shore the roof, sustained a head injury while installing a beam.

The underground Bull Mountain No.1 operation near Roundup operates a single longwall and one continuous mining machine development section in the Mammoth seam.

It has 197 employees and produces about 3650 tons daily, according to 2010 federal data.