WRIGHT, Wyo. (May 14, 2009) - Thunder Basin Coal Company's Black Thunder mine near Wright, Wyoming, surpassed 365 days and 2.5 million employee-hours without a single lost-time safety incident on April 28, 2009.

During that time, Black Thunder's 1,200 employees have produced more than 8 percent of the annual U.S. coal supply from this world-class mine in the Powder River Basin of Wyoming.

"This record safety achievement is a real tribute to the men and women of Black Thunder," says Ken Cochran, president and general manager of Thunder Basin.  "The employees have each made a personal commitment to safety and are really working together to eliminate all incidents and injuries every day of every year."

This achievement exceeds the mine's previous safety record of 1.7 million employee-hours worked without a lost-time incident during 2001, which earned Black Thunder the Sentinels of Safety Award in recognition for operating the safest surface mine in the United States.

In 2007, Thunder Basin was the first of Arch Coal's subsidiaries to adopt a behavior-based safety process to target at-risk behaviors.  The Thunder Basin SABERS (Safety Actions Bring Employees Real Satisfaction) process includes peer-to-peer observations and problem-solving leadership.  

"Through our SABERS initiative, employees are empowered to be the primary drivers in the safety process," says Thunder Basin's Safety Manager Tim McCreary.  "This level of individual engagement is helping drive our safety performance to the next level."

St. Louis-based Arch Coal, Inc. (NYSE:ACI) is one of the largest U.S. coal producers.  Through its national network of mines, Arch supplies cleaner-burning, low-sulfur coal to fuel roughly 6 percent of the nation's electricity.  Arch attained an overall safety record in 2008 that was three times better than the national coal industry average, representing the company's best year on record as measured by total incident rate and lost-time incident rate.