Insufficient pillar support and activity in areas that should not have been mined caused the August Crandall Canyon mine collapse , federal investigators found . Feds : Violations by Utah mine 's operator led to 2007 collapse that killed six . Score: 6 Mine operator fined more than $ 1.5 million .
Feds : Violations by Utah mine 's operator led to 2007 collapse that killed six . Score: 6 Mine operator fined more than $ 1.5 million .