Tag Archives: Mine Accident

Root Cause Analysis - Incident Investigation

More Info about Deadly Mine Explosion

By Kim Smiley

Around 3 pm on April 5, 2010 in Montcoal, West Virginia, a huge explosion rocked the Upper Big Branch South mine killing 29 (Click here to read previous blog on the topic).  The toxic gas concentration in the mine remained so high after the accident that Mine Safety and Health Administration investigations were not able to enter the mine for more than two months after the accident.  The final report is still two to three months away, but the MSHA has developed a working theory on what caused the mine explosion.

According to a recent NPR article, investigators believe they have found the source of the spark that started the chain of events that lead to the massive mine explosion.  A longwall mining machine was in operation inside the mine, creating sparks as it ate through both coal and sandstone.  Sparking may have been worse than usual because investigators found that the carbide tipped teeth on the machine were worn down so that bare metal was contacting the stone and coal.

Sparks are expected during these types of operations so a water sprayer system is typically used to prevent explosions from occurring, but investigations found the water system in Upper Big Branch was not functioning properly.  Additionally, a properly functioning water spray system would help control the amount of coal dust in the air.  Coal dust is an accelerant, which means it will contribute to an explosion if ignited.

Another cause of this accident is the level of methane gas in the environment.  The Upper Big Branch South mine is a particularly gassy mine that naturally emitted high levels of methane gas.  There are still some open questions about the role ventilation may have played in the accident.

Small ignitions of methane gas are not uncommon in coal mines, but large explosions are rare.  According to data collected by Mine Safety and Health News, about 600 ignitions have occurred in the past 10 years without any major mine explosions occurring.

Coal mining involves managing a tricky combination of coal dust, methane and sparks.  Usually, no one gets hurt, but in this case the mixture resulted in a massive explosion that traveled more than two miles inside the mine and claimed the lives of 29.  Performing a thorough root cause analysis can help investigators understand what was different in this case and hopefully help the lessons learned be applied to other mines.

As more information comes available, the Cause Map can be expanded to include all relevant details.  Click “Download PDF” above to view the intermediate level Cause Map for this example.

Root Cause Analysis - Incident Investigation

Mine Deaths in China

By ThinkReliability Staff

Following the successful rescue of all 33 miners trapped in a Chilean mine is some unhappy mine news from China.  A gas blast on October 16, 2010 in the early morning is known to have killed 26 miners, and the 11 miners unaccounted for are believed dead.   In addition to these impacts to the safety goals, the environmental goal is impacted by the extremely high levels of methane gas, the customer service and production goals are impacted by the closure of the mine, and the property and labor goals are impacted by the rescue efforts that have been required.  Unfortunately this is not an uncommon occurrence.  It is estimated that 2,600 people were killed in Chinese mine accidents last year.

It is expected that the miners were mostly killed due to suffocation.  In addition to the lack of oxygen from the extremely high levels of methane (40% compared to the normal level of 1%), the miners were buried by coal dust, released by the gas blast.  The miners were trapped in the mine by the gas blast, of which the cause is as of yet unknown.  This is a question that additional investigation will try and answer.  Additionally more information is needed about the high levels of methane.  The rescuers had difficulty reducing the levels of methane because coal dust was blocking an access shaft, but levels were high prior to the blast, for reasons that are unclear.

More detail can be added to this Cause Map as the analysis continues. As with any investigation the level of detail in the analysis is based on the impact of the incident on the organization’s overall goals.  Because of the high number of deaths (and the high frequency of this type of incident), the Cause Map should end up very detailed in order to provide as many solutions as possible to ensure that the best solutions are implemented to reduce these types of incidents.

Root Cause Analysis - Incident Investigation

Deadly Mine Explosion in West Virginia

By Kim Smiley

Around 3 pm on April 5, 2010 in Montcoal, West Virginia, a huge explosion rocked the Upper Big Branch South mine owned by Massey Energy Company.  At least 25 miners were killed, both from the explosion itself and suffocation caused by high levels of dangerous gases.

There are still 4 miners missing.  The missing miners were working farther back in the mine and the hope is that they were able to reach one of the airtight chambers stocked with enough food, water and oxygen for several days.  Rescue efforts are underway and drilling efforts are ongoing to add additional ventilation so that the gas levels can be reduced to safe levels to allow rescue workers to enter the mine.

This is the worst mine accident in the US in over 20 years. If the 4 missing miners are not found alive, this accident will have the highest number of fatalities since a 1970 mine killed 38 in Hyden, Kentucky.

What triggered this explosion is not known at this time, but both state and federal agencies have initiated investigations.

Even though many details are still unknown, a root cause analysis can be started by building an initial Cause Map.  There was an explosion which means there must have been an ignition source, flammable material and oxygen present.

The source of the flammable material is known since there were high methane gas levels in the mine.  Methane gas is naturally occurring in coal mines and must be continually vented.  It can also be assumed that the mine ventilation was inadequate for some reason since the gas levels built up.  Coal dust accumulation may have also contributed to the accident since powdered combustible material in an enclosed space is a very explosive combination.

The source of the spark that ignited the explosion is still unknown.

More information will become available as the investigation proceeds and a more detailed Cause Map can be built as additional causes are added.

Media reports about the accident have discussed past safety violations cited at the mine, but it won’t be clear if the accident was preventable until the investigation is completed.  What is known that in March 2010, the Mine Safety and Health Administration cited the Upper Big Branch mine for 53 safety violations.  In additional to the recent citations, there was also a troubling increasing trend in citations, which more than doubled between 2008 and 2009.

Hopefully, the information obtained during the investigation will provide useful lessons learned that can be implemented to prevent a similar accident in the future.