The U.S. Mine Safety and Health Administration released its final report March 25, 2019 on the Oct. 25 fatality at the Lee Smith Mine. The mine, which is operated by Small Mine Development, was issued a citation by the agency.
“The accident occurred because mine management policies, procedures and controls were inadequate to ensure the establishment and maintenance of safe ground conditions where persons work or travel,” the report said.
Keith Jones, general manager of Small Mine Development, said of the MSHA report, “We take exception with the root cause analysis and their conclusions. We’ve commented to MSHA on some of that, but that was not incorporated into their final report.”
“The procedures at Smith at the time of the incident were very much industry standard,” Jones said, “with QA/QC (Quality Assurance/Quality Control) controls in place. Testing of cylinders in the area had indicated acceptable strengths. We have installed about 2.6 million tons of CRF (cemented rock fill) at this particular mine without incident.”
The Lee Smith Mine is about 50 miles north of Elko. Idaho-based SMD operates the mine for Jerritt Canyon Gold, a Toronto-based private company. SMD began production there in 2010, and Jerritt Canyon Gold purchased the Jerritt Canyon Complex in 2015.
At the time of the accident MSHA was three days into conducting a regular inspection of the mine.
The MSHA report said Jason Holman, a 42-year-old powderman with eight years of experience, was fatally injured. Holman started work at 6 a.m. that day and was near the end of his 12-hour shift when the accident occurred. Holman and Robert Pierce, the batch plant operator, were loading blastholes and had also been installing air and water utility lines and installing ground support. At 4:15 p.m. Holman backed a truck into their work area and Pierce arrived in a tractor.
Holman and Pierce had nearly completed loading blastholes when Pierce received a radio call about a broken air line in need of repair at a different location in the mine. Holman continued loading blastholes while Pierce went to the cab of the powder truck to get tools to repair the air line. At 4:50 p.m. the cemented rock fill in the roof of the area collapsed. Pierce was thrown out of the cab of the truck by the force of the collapsing CRF.
Pierce moved toward the back of the truck looking for Holman, but had to retreat because CRF continued to fall. Pierce called Todd Caruso, the acting supervisor, at 4:55 p.m. Caruso and another miner arrived about 10 minutes later. The rear of the truck was covered with a large amount of CRF.
Jones said they estimated that about 67 tons of CRF fell. The cavity created in the ceiling was a domed area about 19 feet across with a maximum height of about seven feet.
The MSHA report said the mine management and mine rescue team members recovered Holman and transferred him to the Elko County sheriff’s coroner at 4:45 a.m. the next morning.
The report said the Lee Smith Mine uses underhand cut-and-fill throughout 80 percent of the mine. With this mining method, an operator drives cuts beneath previously installed CRF, so that the roof of an area consists of CRF which was installed in the overlying level. Cuts range from 12 feet to 20 feet but are normally 15 feet wide. The area where the Oct. 25 accident occurred was about 18 feet wide and 21 feet high. An operator had installed CRF in the previously mined overlying level about two and a half months prior to the accident.
CRF is made of aggregate and slurry mixed by a front end loader operator. The MSHA report said that ideally, CRF remains on the surface for 30 minutes between mixing and delivery. The investigators found the operator had stockpiled the CRF on the surface for up to two hours before loading it into trucks for delivery underground.
“CRF should always be laid in position soon after mixing to avoid setting and stiffening,” the report said.
Underground, an operator of a bulldozer with a jammer attachment pushes the CRF into the open drift. The operator is supposed to report if there are any CRF deficiencies. The MSHA report said investigators found inconsistencies in how inferior CRF was handled when reported.
“In some cases when the CRF was too wet, the jammer operator mixed in dryer CRF,” the report said. “Other operators would either set the inferior CRF aside or continue to place the inferior CRF into the drift. … Investigators found a lack of quality control in the selection of aggregate, mixing, delivery and placement of CRF.”
The MSHA report said that since the accident, “Mine management has revised policies, procedures and controls for producing the CRF and provided training on the policies, procedures, and controls for the employees. Mine management is conducting follow-up testing of the backfill and load cells have been calibrated at the batch plant.”
Jones said the mine received the accident citation within the past couple of weeks. He said it usually takes about six weeks after the citation is issued for a penalty to be assessed.
Following the accident, operations at the Lee Smith mine were halted and the miners were furloughed until December. The mine resumed operations in stages after that. Jones said that currently the volume of work is a little less that it was prior to the accident, but the mine is “essentially full operation for the scope of work that’s before us right now.”
Previously, there had been around 80 employees at the mine.