FALL OF ROOF OR BACK at Bronco Utah Operations, LLC.
An unplanned Roof Fall occurred at an unknown time. Right Return Air Course of Main West, Entry #6 XC 21. Approximately 5 ft. wide by 6 ft. long and 4.5 ft high. It is NOT at or above the anchorage, but has impeded travel. No injuries, entrapment and no ventilation interruption. Preliminary diagnoses; Strata failure due to deterioration of the seam transition area.
U.S. Mine Safety and Health Administration