WRIGHT, Wyo., June 2, 2010 – Thunder Basin Coal Company’s Black Thunder mine has surpassed two years and nearly 6.0 million employee-hours without a single lost-time safety injury. Additionally, Black Thunder recently was honored with the prestigious 2010 Governor’s Safety Award for Wyoming’s best safety program and the Wyoming State Mine Inspector’s Safety Award for large mines. Coal Creek mine has worked more than four and a half years, or 1.3 million hours, without a single lost-time injury. Coal Creek mine also earned the Wyoming State Mine Inspector’s second place Safety Award among small mines.

“Congratulations to the employees of Black Thunder mine for working two years and Coal Creek mine for working four years without an injury,” said Kenneth Cochran, president and general manager of Thunder Basin, a subsidiary of Arch Coal. “Their ongoing commitment to risk minimization and safe work practices is exemplified in these remarkable safety accomplishments.”

Black Thunder and Coal Creek mines are located in the Powder River Basin of Wyoming. Thunder Basin’s 1,800 employees produce more than 10 percent of the annual U.S. coal supply and provided coal to 116 power plants in 25 states in 2009.

St. Louis-based Arch Coal, Inc. (NYSE:ACI) is the second largest U.S. coal producer. Through its national network of mines, Arch supplies cleaner-burning, low-sulfur coal to fuel roughly 8 percent of the nation’s electricity. Arch’s lost-time incident rate was just one-fourth the national coal industry average during 2009, representing the company’s best year on record.