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Tri-Star Mining, Inc.
Job No. 3
Fall of Highwall

Barton, Maryland
April 17, 2007
No. Killed - 2



Final Accident Investigation Report (3.4 Mb) 

Accident narrative taken from a Powerpoint Presentation  created by Gregory Fetty

Between 9:25 a.m. and 10:00 a.m. on 4/17/2007, a highwall failed resulting in the entrapment of an excavator operator and a bull dozer operator.  The estimated size of the highwall that collapsed was 150 to 170 feet high by 100 to 150 feet long and approximately 50 feet thick.  The highwall had been examined just prior to the collapse.

At approximately 10:15 a.m., an MSHA inspector who was at a nearby job site was notified of the accident.  The inspector issued a verbal 103(k) Order at approximately 10:30 a.m. and immediately notified the district office.  Two accident investigators were dispatched to the accident scene and arrived at approximately 12:00 p.m.

Shortly after investigators arrived, a decision was made to begin tramming two large Bucyrus Erie shovels towards the accident location.  The shovels were travelling towards the scene from different areas.  The weight of the shovels caused them to sink into the ground, delaying their arrival.

Loading out of the material began at approximately 6:00 p.m. on the date of the accident and continued for approximately 30 hours.  Haul trucks with a 100 ton capacity were loaded at a rate of 25 to 35 trucks per hour.  The condition of the highwall was extremely hazardous.  During excavation, recovery was halted on different occasions to assure the safety of the workers.

As material was removed, rocks were encountered that were too large for the shovel to load out.  The rocks had to be chipped by the shovel in order to be moved, which delayed recovery.  As material was loaded from the toe, additional material would slide towards the shovel until it reached the angle of repose.

Shortly after midnight on 04/19/2007, a decision was made to use explosives to remove a large overhang that was above the shovel.  This time was also utilized to refuel and service the shovel.

The shovel had to be moved out of the pit prior to the detonation of shot.  Due to soft bottom conditions, it took approximately 5 hours to move the shovel approximately 500 feet.

Two shots had to be detonated to remove the overhanging material.  Again, the shovel had difficulty tramming due to roadbed conditions.  By 7:30 a.m., the shovel resumed loading.

At approximately 6:00 p.m., the counterweight of the excavator was uncovered.  As work continued in the direction of the highwall, it continued to be unstable.

As work continued to remove material, the blade of the bull dozer was uncovered at approximately 9:42 p.m.  Additional removal of material indicated the slide cause the two machines to be pushed together.  Other pieces of the machines were removed from the pit as work progressed.  At approximately 3:45 a.m., a decision was made to halt the removal of additional material until day light is available.

The shovel could no longer safely extend to reach additional material.  An excavator was utilized to remove the material from atop the fallen material.  When enough material was removed to expose both pieces of equipment, an examination revealed the body of the excavator operator was still inside the cab.

The body of the excavator operator was discovered at approximately 10:20am in the location of the crushed cab of the machine.  The arm of the excavator was beneath fallen material and had to be removed.  The excavator was then pulled off the bench to facilitate recovery of the victim.  The victim was recovered at approximately 2:40 p.m.

While the excavator operator was being removed from his cab, work continued to remove material from atop the bull dozer.  At approximately 2:40 p.m., the bull dozer operator was discovered in the cab of the machine.  Work continued to move the recover the cab section of the dozer to a safe location to extricate the victim.



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