According to the agency’s final investigation report released this week, contract employee Cody Alwin Brown, 29, was killed at the Campbell County mine property on the morning of September 1, 2011 when a restraining/tong wrench struck him in the upper body and limbs at well site 26.

“Brown and three other drilling personnel were attempting to remove drill pipe that had become bound up and was stuck in a drilled hole, approximately 1900 feet deep.” MSHA said.

“The wire rope cable used to restrain the wrench broke, causing the wrench to strike Brown.

“Brown had just completed applying the wrench to the drill pipe to hold the applied torque when the wire cable failed … the wrench rotated around toward Brown at a high speed, throwing him into the drill rig.”

Brown had 17 months of drilling experience.

His training records were reviewed and found to be current with no deficiencies.

In its root cause findings, federal officials said that the accident occurred when Brown was struck by the rotating wrench clamped on a drill chuck after chuck torque had been applied.

He subsequently did not exit the area when pressure was released from the drill engine clutches and the drill pipe revolved, including the protruding tong wrench.

“The one-half-inch cable rope attached to the tong wrench and to the derrick was being used to restrain rotation of the pipe under torque,” MSHA said.

“The wire rope was too long to provide the maximum restraint required to hold the torque energy on the pipe.

“As the rope took the excessive load due to the length it failed, allowing the tong wrench to rotate, striking the deck hand forcefully.”

In addition to the snub line issue, officials said there was no immediate need for anyone to be on the drill deck aside from the driller.

In its corrective actions, the agency ordered Weston Engineering to establish standard operating procedures with provisions that a drill operation should not use the snub line when attempting to hold torque on the drill pipe.

It also developed a SOP detailing the positioning of personnel prior to release of any stored energy.

All drilling personnel received training on the procedure prior to further mine drilling operations.

Additionally, MSHA found that task training was inadequate to inform personnel involved with drilling operations of the acceptable snub line size and the safe positioning during drill work or activity related to drilling.

To correct the issue, MSHA ordered that all drilling personnel should receive task training detailing proper examination of all components of the drilling operations and adequate tool and equipment size for the intended purpose.

Investigators issued a 107(a) order to Weston Engineering when stored energy was found in the drill pipes at the accident scene.

The energy was released under controlled measures and the order was terminated.

It also issued a 104(d)(1) citation to Weston Engineering and Peabody Powder River Mining for their respective violations of 30 CFR Section 77.1713(a).

“At least once during each working shift, or more often if necessary for safety, each active working area and each active surface installation shall be examined by a certified person designated by the operator to conduct such examinations for hazardous conditions and any hazardous conditions noted during such examinations shall be reported to the operator and shall be corrected by the operator,” the report stated.

“On September 1, 2011, the on-shift examination was conducted by a miner who was not certified to conduct workplace examinations.

“The miner then entered the results in the book kept for that purpose and signed the record.”

The North Antelope Rochelle mine, near Gillette in Wyoming, is operated by Peabody Energy subsidiary Peabody Powder River Mining, produces more than 105 million tons of coal annually and employs 1310 miners.

The mine normally has up to 300 contract employees.

The last E01 inspection at NARM was completed August 11, 2011.

The non-fatal days lost incidence rate for the mine in the previous quarter was 0.3, versus the national NFDL incidence rate for surface coal mines of 1.