Dugout Canyon was shut down by the US Mine Safety and Health Administration after a “heating event”

The company worked closely with MSHA to assess the situation and restart the mine, Arch Western Bituminous Group president Gene DiClaudio said.

“We want to extend our great appreciation to the MSHA team for its diligence and hard work during the outage,” he said.

More than 100 of Dugout Canyon's 275 employees are returning from other company operations in Utah and Colorado where they had been working on temporary assignment.

“We were pleased so many Dugout employees offered to work at other locations while the mine was idle,” DiClaudio said.

Dugout Canyon mine produces approximately 2% of Arch's total annual output.

Arch is the largest coal producer in Utah, operating the Sufco, Skyline and Dugout Canyon mines with a total workforce of approximately 800.

St. Louis-based Arch Coal is the second-largest US coal producer and supplies cleaner-burning, low-sulfur coal to fuel roughly 8% of the nation's electricity through its national network of mines.

The company also ships coal to domestic and international steel manufacturers as well as international power producers.

The June closure was the second in as many months for Dugout Canyon.

A similar incident on April 29 in another part of the mine idled production until MSHA approved resumption of normal mining on May 21.