An employer’s failure to ensure that employees turned equipment off before performing maintenance led to a fatality, according to a federal report.
The U.S. Mine Safety and Health Administration (MSHA) investigated the incident that saw a 24-year-old worker killed when he became entangled in a rotating drill steel while changing out the steel on a running machine.
He was found entangled in drill steel
Noah Dinger was working for contractor Moran Mining USA Inc. at the Stillwater Mine, an underground platinum mine in Stillwater County, Montana.
At 7 p.m. on Nov. 12, 2023, Dinger started his shift and was assigned to operate a roof bolting machine along with another miner who followed along in a truck to clean up debris.
At midnight, the other miner was pulled away to perform a different task. When he resumed his work following the roof bolting machine, he noticed that Dinger wasn’t in the cab of the vehicle.
The other miner walked down to where the roof bolting machine was parked and found Dinger entangled in the machine’s drill steel. He tried to free Dinger from the steel, but failed. Eventually, he ran to his truck to get a hacksaw, which he used to cut Dinger’s clothing to free him and then began CPR.
After spending some time performing CPR, the other miner realized he needed help and called for a medic. He then resumed CPR until the medic arrived at 2 a.m. on Nov. 13.
Later, emergency responders arrived and pronounced Dinger dead at 5:11 a.m.
Operator’s manual warnings ignored
MSHA investigators examined the roof bolting machine, which was fitted with a bolt-driver, bolt carousel and a rotating drill head.
The machine is operated from controls found inside the cab, which allows the operator to drill holes and install bolts from a safe point of operation. The investigation found no defects with the machine that would have contributed to the incident.
Investigators determined that the only time the operator needed to approach the bolt carousel and drill head was when they were refilling the bolts or when changing drill steels. They found evidence of a broken bit and the installation of a new drill steel.
While consulting the machine’s operator’s manual, the investigators found a warning statement indicating that no one should be near the drill or bolt driver while it was in operation. It also warns against working around the machine while wearing loose clothing.
Interviews with the other miner revealed that when he checked on Dinger, he discovered that the machine was still operating and that he had to de-energize it before he attempted to free him. This led investigators to determine that the warnings in the manual weren’t followed.
Employer policy wasn’t followed
A similar incident that didn’t result in a fatality occurred at the mine on June 18, 2023.
Following that incident, the mine implemented a new policy prohibiting its workers and contractors from threading drill steel by hand while the drill is rotating.
However, MSHA determined that this policy wasn’t followed during the incident.
New procedure requires 2 workers, signage, electronic barriers
Investigators found that the incident’s root cause was the contractor’s failure to ensure that the power was off and that the equipment was blocked against hazardous motion.
To prevent a similar incident, the contractor developed a new written procedure that requires two miners to operate roof bolting machines.
It also placed signage at the front of the machine restricting access while the drill is energized.
The contractor is also working with the equipment manufacturer to install electronic barriers that will de-energize the machine automatically.