Utah's largest coal producer will bypass $100 million of coal to avoid the kind of danger that led to the collapse at Crandall Canyon.
Arch Coal Inc. decided to pull back where a coal seam dips nearly 3,000 feet underground.
The Utah Geological Survey says St. Louis-based Arch Coal is sacrificing 4 million tons of coal at the Dugout mine in Carbon County for safety.
A ton of coal sells for about $26.
Dugout still has plenty of other coal that can be mined. Arch plans to continue longwall mining there until 2015, following by a couple of years of retreat mining, said Michael Vanden Berg of the Utah Geological Survey.
Retreat mining taking down pillars in a controlled collapse can be risky. Federal regulators in a report issued Thursday said the operators of Crandall Canyon cut into load-bearing coal pillars, bringing down a large section of the mine.
The Aug. 6 collapse trapped six miners whose bodies haven't been recovered. Three others were killed during a rescue attempt.
Utah geologists say Arch Coal is taking precautions in longwall mining to avoid mountain "bounces" that plagued Crandall Canyon.
The company wasn't immediately available Friday for comment.
Crandall Canyon was sealed off after last summer's twin disasters. In April, the same operator closed another central Utah mine, the 2,750-foot-deep Tower mine, because of "unusual stress conditions" on mine pillars there.