The US Mine Safety and Health Administration released its final investigation findings for the death of bulldozer operator David Middleton, 28, who was killed on November 2 at Nally and Hamilton Enterprises’ Mill Branch operation in Harlan County.

The victim, who had eight years mining experience, received multiple injuries when the Caterpillar D6T dozer he was operating overturned along the top of a reclaimed slope.

The dozer travelled about 290ft down a hill, overturning several times.

The unit finally came to rest on its right side on the mine’s access road.

Middleton died on November 14 from his injuries.

“The investigation team determined that while conducting reclamation work along the top of the slope, the bulldozer's right side track encountered a large rock in unconsolidated material,” MSHA said in the report.

“The rock slid off the edge of the working area while underneath the right side tracks of the bulldozer, causing the bulldozer to slide over the edge and begin overturning.”

Officials evaluated the D6T and reported no visual damage to the unit’s rollover protective structure and no defects were found with the service and parking brake controls.

Weather also did not play a contributory role in the incident, investigators said.

“The accident occurred because the company failed to implement policies and procedures to ensure that the bulldozer operator was able to maintain full control of the bulldozer while conducting reclamation work near extreme slope conditions,” MSHA concluded in its findings.

“The victim was wearing a seat belt.

“However, the lap belt design failed to prevent the operator's body from excessive movement, which resulted in injuries that eventually caused the death of the victim.”

To rectify the issue with the operator’s procedure implementation, officials ordered the establishment and implementation of a policy outlining all procedures to be followed when working near extreme slope conditions.

The miner also provided additional training to equipment operators on the newly implemented procedures to identify extreme conditions, operate equipment safely in extreme conditions and recognize the limitations of equipment in extreme conditions.

Nally and Hamilton was issued a 104(a) citation for a violation of 30 CFR Section 77.1607(b).

“It has been concluded that management failed to ensure the bulldozer operator maintained full control of the Caterpillar D6T bulldozer … while conducting reclamation work at the top of reclaimed mine slope,” MSHA said.

“Mobile equipment operators shall have full control of the equipment while it is in motion.”

The Mill Branch mine Closplint has been active since July 1996 and produces 1500 tons of coal per day from the High Splint, Middle Splint, and Low Splint coal seams.

The last regular federal safety and health inspection was completed on May 12, 2011.

The mine's non-fatal days lost incidence rate for 2011 was 10.54, versus the national average in its class of 1.1.