According to SNL Financial, the US Mine Safety and Health Administration approved the plan following an underground assessment which failed to detect any carbon monoxide last week.

The new ventilation plan reportedly included tighter air controls at the mouth of the headgate to reduce the air reaching the fire area.

The mine produced about 1.7 million tons in the March quarter.

Unsafe carbon monoxide levels triggered the Deer Run evacuation on March 26.

A separate mine fire incident shut down Deer Run for a few weeks starting from mid-July 2014.

It’s not clear when Deer Run will restart its longwall.