A heavy equipment operator was killed when the excavator he was operating became engulfed in lime kiln dust that was being removed under a newly developed process that workers expressed safety concerns about.
Workers spoke up about the process at safety meetings, and while the mine operator said it would keep an eye on things, miners were told to continue using the procedure despite their safety concerns.
Mine closure leads to removal of lime kiln dust
Stuart Moore was a heavy equipment operator at Kimballton Plant No. 1 located in Giles County, Virginia. The plant consists of an underground limestone mine and preparation plant, although limestone production stopped on Feb. 10, 2021, for economic reasons.
The mine began removing lime kiln dust beginning in July 2021. Lime kiln dust is a waste byproduct generated from processing limestone at the preparation plant. As the mine operator, Lhoist North America of Virginia, was preparing to abandon the mine it began removing its stock of lime kiln dust to reduce potential pH level impact to the local water table.
Miners used bulldozers and excavators to collect the dust, another excavator would load the dust onto haul trucks and the haul trucks would transport the dust to a surface storage area.
Mudslide on haul road causes delay
On June 20, 2022, Moore started his shift at 7 a.m. and was transported underground to his excavator on Level 7 of the mine. He drove the excavator to Window 13 and began loading haul trucks. Windows are openings connecting the different levels of a mine and are used for conveying materials between the levels.
Sometime after noon, Moore finished loading from Window 13 and moved his excavator to Window 15 on the same level and continued to load haul trucks. Nikko Shamburger, a haul truck driver, was preparing to have his truck loaded by Moore, but Moore told him to stop his truck and wait because mud and large rocks had broken through at Window 14, covering the haul road.
Material slides from upper level, buries excavator
At 2:45 p.m., Moore flashed the lights of his excavator at Shamburger, indicating he could resume operations. Shamburger backed his truck toward the excavator and felt the truck start to slide. Moore honked his horn at Shamburger, which was a normal procedure when a truck was in the correct position to be loaded. When Shamburger applied the brakes, the truck slid to the left and Shamburger felt the bucket of Moore’s excavator hit his truck.
Shamburger radioed to Moore, but Moore didn’t respond. Other haul truck drivers heard the radio call and came over to investigate. They found most of Moore’s excavator was buried under material that slid from Window 15 onto the haul road.
The material around the excavator was firm enough to walk on and Shamburger and the other drivers attempted to dig Moore out by hand. Their attempts were unsuccessful, so excavators were brought in to remove material from around Moore’s excavator. By 4:35 p.m., enough material was removed that the mine’s superintendent was able to access the excavator’s cab and check Moore for a pulse, which he couldn’t detect.
Moore was removed from the excavator and transported to the surface. Emergency medical services arrived and pronounced Moore dead.
New procedure introduced 3 weeks before fatal incident
Investigators with the U.S. Mine Safety and Health Administration (MSHA) learned that the mine operator had introduced a new lime kiln dust removal process about three weeks before the incident occurred.
A bulldozer would gather the dust close to a window on Level 4, and an excavator would dump the dust into the window. The dust would then flow through the window down to Level 7 where another excavator would load it onto haul trucks that would transport it to the surface storage area.
However, the lime kiln dust didn’t flow freely from Level 4 to Level 7. Instead, it accumulated as it was dumped into a window, causing an unstable condition. These accumulations repeatedly built up and collapsed randomly as the dust traveled down to Level 7, creating hazardous ground conditions. The mine operator didn’t take down or support the hazardous ground conditions before allowing work in these areas.
Further, the mine operator didn’t ensure that miners followed other procedures that were established to prevent these conditions from occurring, although investigators found that even if followed, the preventative measures wouldn’t have adequately protected miners in the area.
Miners, contractors expressed safety concerns to management
Miners and contractor staff expressed their concerns and told mine management about the uncontrolled movement of lime kiln dust. The mine’s management said it was keeping an eye on the situation.
Just three days prior to Moore’s death, another heavy equipment operator had a close call that almost resulted in her being engulfed by material. She told management that lime kiln dust came down through Window 15 so fast that it almost surrounded the excavator she was operating. She said the area wasn’t safe and didn’t want to work there until the hazard was corrected. The next day, the mine operator reassigned her to another job on the surface.
Listening to frontline workers could have prevented tragedy
MSHA investigators concluded that the root causes for the incident were the mine operator’s failure to:
- take down or support hazardous ground conditions before permitting work in the affected area, and
- adequately examine ground conditions in areas where work was to be performed and as ground conditions warranted during the work shift.
There’s a third root cause that MSHA didn’t mention: The mine operator’s failure to listen to the safety concerns of its workers and contractor staff.
These frontline workers had the best vantage point to observe the hazard and how it could affect them, yet the only response, according to the MSHA report, was management staff saying they’d keep an eye on the situation.
On top of workers speaking up about their safety concerns, an equipment operator had a close call that mirrored Moore’s incident just three days prior to his death and still nothing was done.
If management had truly listened to the workers’ concerns, this fatal incident could have been averted.