Alpha spokeswoman Samantha Davison told ILN that longwall operations recommenced during the afternoon shift on April 21 and the mine returned to normal operating schedules on Monday.

Cumberland had been idled since April 8, when the US Mine Safety and Health Administration issued an imminent danger order for elevated methane levels and ordered its closure.

While Davison did not confirm any specifics on the methane readings, she did say the affected area was in a remote portion of the mine where workers did not travel or were required to work.

“The elevated levels of methane were due to the geology of the mine,” she said, adding that the company continued to work in tandem with MSHA officials.

In its initial US Securities and Exchange Commission filing Alpha said no injuries occurred in connection with the cited condition.

Imminent danger orders are issued by the MSHA under section 107(a) of the Federal Mine Safety and Health Act, also known as the Mine Act.

Cumberland, which operates with continuous miners as well as a single longwall, extracts from the Pittsburgh 8 seam.

It produced almost 6.5 million tons in 2012.

Alpha obtained Cumberland in its takeover of Foundation Coal in July 2009.