By Steve Fiscor, Editor-in-Chief
On June 29, 2011, the Mine Safety and Health Administration (MSHA) held a public briefing on its investigation into the explosion at Massey Energy’s Upper Big Branch (UBB) mine in West Virginia. Delivering a PowerPoint presentation at the National Mine Health and Safety Academy in Beaver, W.Va., Kevin Strickland, MSHA’s administrator for coal mine safety, concluded the most likely cause of the accident was a coal dust explosion that propagated from a methane ignition that occurred while the shearer on the longwall was cutting sandstone. “This explosion could and should have been prevented by the mine operator,” Strickland said.
At 3:02 p.m. on the day after Easter Sunday (April 5, 2010), 29 miners were killed in an explosion at the UBB mine, the worst U.S. mining accident since 1970. Rescuers found seven men on the main haulage. A dozen miners were found either on the longwall face or in the Headgate 1 North area. Nine more were located in the Headgate 22 (HG 22) development section. One victim was located at transfer point between the longwall panel belt and the mainline conveyor.
MSHA investigators believe the UBB explosion was initiated from a limited amount of methane likely ignited by the longwall shearer. The shearer had missing and faulty sprays, which would ordinarily suppress an ignition. Investigators found inadequate rock dust in the longwall tailgate and believe the methane ignition transitioned into a massive coal dust explosion.
The UBB mine opened in September 1994. Mining coal from the Eagle seam, which is considered a high-volatile bituminous coal, it produced 1.2 million raw tons in 2009. The mine consisted of four sections, three continuous miner sections and one longwall. The longwall was briefly moved to the overlying Logan’s Fork mine before returning to the UBB in 2009. The average seam height was 54 inches and the average mining height was 84 inches. The mine employed 234 underground miners and two surface operators. The mine also employed numerous contractors. It operated overlapping and staggered shift schedules. Two production shifts followed by a maintenance shift (midnight shift).
The Eagle coal seam can be found as deep as 1,200 ft in the region. It has been overmined extensively and it has a history of floor heave and inundations. An explosion occurred in longwall panel No. 2 West (LW2 West) in 1997 and was attributed to a roof fall. UBB reported inundations in 2003 and 2004. The mine exhibited floor cracks and regional faulting.
The Day after Easter
The UBB mine shut down for Easter Sunday. The maintenance shift was reportedly uneventful. The day shift production and support crews entered the mine between 6:00 a.m. and 7:30 a.m. through two portals, the Ellis and UBB portals. The first call out came at 7:30 a.m. followed by a call out every 30 minutes. The longwall ran until 11:00 a.m. (two passes). The longwall was down until 2:15 p.m. because of mechanical problems with the shearer. The last call out (2:30 p.m.) signaled the shearer was located at shield 115 and cutting toward the tailgate.
The longwall shearer was cutting through sandstone in the tailgate. The shearer was shut off by the tailgate side remote control at 3:00 p.m. Water supply was manually shut-off at the headgate. The shearer’s high voltage power was manually disconnected. Prior to the explosion, the longwall face crew travels 400 ft from the tailgate in about two minutes. Considering the confined space afforded by the shields, it’s safe to safe they were running scared. At the same time, the Tailgate 22 (TG 22) crew calls out for track clearance at crosscut 78 (XC 78) at 3:00 p.m. The HG 22 miners are also in the maintrip, ready to leave the section.
At 3:02 p.m., electrical power at the Ellis Portal goes offline. Dust and debris blows out both portals. Mine fans at the UBB portal stall. The CO monitoring system sounds an alarm. Several miners near the portals evacuate the mine. Surface personnel begin notifying underground personnel to evacuate.
Tim Blake, one of the two survivors of TG 22 crew, recounted that he felt the wind pick up, immediately blinded by dust, held his breath and donned his self-contained self-rescuer (SCSR). Blake sat for a couple of minutes in the dark and dust. When the dust decreased, he placed SCSRs on crew members and removed some of the men from the mantrip. Approximately 45 minutes later, Blake realized his SCSR was almost depleted and reluctantly began to walk out of the mine. The mantrip was found at XC 67.
Approximately 20 to 30 minutes after the explosion, several managers started into the mine from both the Ellis and UBB portals. Blake walked about 20 crosscuts when his caplamp was spotted by incoming managers.
Jonah Bowles, safety director, Marfork mine, called the MSHA hotline at 3:30 and reported an air reversal on the beltline at the Ellis Portal. He reported concentrations of 50 to 100 ppm CO and the mine was being evacuated. No one was trapped or injured. The hotline operator calls MSHA District No. 4 at 3:42 p.m. Immediately, MSHA contacted the mine operator. The agency determined a serious event had occurred and issued a 103(j) control order. The agency began its emergency response.
UBB managers transported the TG 22 crew out of the mine, while others traveled further into the mine on foot, bare-faced with SCSRs, according to Strickland. Mine rescue teams explored the longwall face and found the HG 22 mantrip. The mine was evacuated at 12:45 a.m. due to explosive gas and smoke. The mine rescue teams had found 18 victims. “Massey did not have an accurate count of the missing miners until 1:40 a.m. Tuesday, April 6, 2011,” Strickland said. The agency monitored seismic activity and gas through boreholes. The mine rescue teams made several more attempts to find the four missing miners. The final missing miner was found at 11:20 p.m. Friday, April 9, 2011. Recovery of the victims was completed at 12:57 a.m. Tuesday, April 13.
Accident Investigation
MSHA’s accident investigation officially began April 12, 2010. The underground investigation was delayed until June 25, 2010. Hazardous conditions, water accumulation and high concentrations of CO hindered the underground investigation. The agency interviewed 266 individuals and called 34 back for a second interview. A total of 18 Performance Coal and Massey Energy executives exercised their Fifth Amendment rights and declined to be interviewed, according to Strickland.
More than 100 MSHA employees were involved in the onsite investigation. The agency assembled investigative teams for dust, mapping, electrical, ventilation, geology, evidence collection, etc. An additional 45 technical support personnel performed tests and other technical activities. MSHA personnel were posted as guards at the three portals during the investigation.
Strickland recognized several other parties involved in the investigation, including the State of West Virginia, the West Virginia Governor’s Independent Investigative Panel, the United Mine Workers of America, Moreland & Moreland, Massey Energy and Internal Review.
To date, more than 84,000 pages of documents have been assembled. More than 950 maps have been generated and logged into evidence. More than 23,400 photos were taken along with 18 videos. A total of 1,060 separate pieces of physical evidence had been collected.
Chronic Ventilation Problems
As far as ventilation, the mine employed a push-pull system with two blowing fans and one exhausting fan. The Bandytown fan ventilated the area of the explosion. The ventilation plan required 15,000 cfm in the last open crosscut for the continuous miner sections. The mine did not maintain the minimum air quantity at HG 22. The ventilation plan required 30,000 cfm on the longwall intake.
Prior to December 13, 2009, the longwall was ventilated with approximately 60,000 cfm. Failure of ground control in the longwall headgate necessitated a change to relocate the HG 22 return air course on December 23, 2009. The longwall ventilating quantity was increased to approximately 140,000 cfm. The HG 22 quantity was approximately 22,000 cfm.
Between approval plans for TG 22 and the start of the section, the quantity of air on the longwall decreased to 50,000 cfm in three days. In mid-February and the beginning of March 2010, Strickland noted several unexplained fluctuations in longwall air quantity: 110,760 cfm (Feb. 24, 2010), 77,700 cfm (Feb. 25, 2010), 82,368 cfm (March 5, 2010), and 113,978 cfm (March 6, 2010).
On March 9, 2010, unapproved changes were cited in the longwall tailgate. Prior to the order, the longwall quantity was about 80,000 cfm. After the correction of the cited condition, the longwall quantity was approximately 77,000 cfm. The mine operator decided to install equipment regulating doors March 17, 2010. The operator said this was done to ensure adequate air for the HG 22 section. The longwall intake quantity was reduced by about 20,000 cfm to 60,000 cfm by March 22, 2010. The HG 22 air quantity increased slightly, Strickland said.
Measurements for numerous air splits were not recorded. “Measurements for air splits were recorded intermittently,” Strickland said. “Measurements for belt air quantity and direction were not recorded and measurements for evaluation points were either incomplete or never recorded.”
UBB suffered from chronic ventilation problems. Strickland referred to the number of ventilation-related citations and orders. He also cited testimony of those who provided information to the investigators. “Many equipment doors were used in lieu of overcasts,” Strickland said. “They did not reliably separate air courses. They were often left open or damaged, which increased leakage.”
Poor Record Keeping
During its examination of records and from testimony about examinations at UBB, Strickland said the company kept two “sets of books.” The mainstream media (Wall Street Journal, NBC, etc.) quickly seized on this point because the statement brings to mind accountants cooking the books. In reality, however, it was very poor record keeping. Hazards recorded in production and maintenance reports were not listed in required examination books. In one example from a production report, the continuous miner section experienced 1.5% methane. “Power should have been disconnected and the section should have been evacuated,” Strickland said. “Instead, the miners waited 25 minutes for the methane to clear.” In another case, a maintenance report noted a problem with sprays on the shearer.
The preshift examinations for the continuous miner sections on the morning of April 5, 2010, reported few hazards. It was reported six of 10 belts needed cleaning and five and 10 belts needed rock dust. The longwall preshift examination, called out at 2:40 p.m. April 5, 2010, reported no methane, 56,840 cfm of air in the intake, and no hazards. The HG 22 preshift reported one entry that needed rockdust. The TG 22 preshift reported no hazards. The conveyor belt preshift/onshift examination reported most of the belts needed to be cleaned and rock dusted. Production reports for HG 22 and TG 22 were normal.
MSHA said the UBB longwall bleeder system was not examined properly. The company had designated a person to conduct methane checks and examine the longwall bleeders weekly. The designee’s multigas detector had not been activated since March 18, 2010, prior to 7:00 p.m. April 5, 2010 (four hours after the explosion). Any methane problems associated with the longwall would have been noticed if the detector was operating and the examination was conducted properly, Strickland explained. The examiner and his crew left the longwall at 2:30 p.m.
By law, examination books must be counter-signed by upper management. MSHA believes UBB managers were aware that chronic hazardous conditions were not recorded. According to the agency, testimony indicated UBB management pressured examiners to not record the hazards.
Inadequate Rock Dust
UBB had a history of citations associated with rock dusting. The mine was cited with 17 rock dust violations in the one-year period prior to the explosion. Eleven of those citations mentioned float coal dust.
Interviews conducted during the investigation also indicated rock dust problems. From that testimony, MSHA determined that in general only the track and conveyor entries were rock dusted; some areas were only rock dusted as they were developed; and float coal dust would accumulate in the belt entries.
The mine experienced problems with its bulk duster. The 1.6-ton, rail-mounted pod duster only covered two entries for approximately 10 crosscuts. “A single crew dusted the entire mine on the midnight shift,” Strickland said. “They reported being taken off rock dusting the assignment regularly to do other work.” They also said they could not regularly find a motor to pull the rock dusting pod. The rock dusting crew experienced a high rate of turnover. On top of all that, they only had a limited amount of time to apply rock dust during the shift.
A properly functioning dust suppression system would have reduced float coal dust generation. Investigators found the water supply used for dust suppression, improperly filtered river water, was inadequate for longwall mining. The tailgate drum on the shearer had seven sprays missing. Some of the sprays were unapproved nozzles. When water was plumbed to the shearer, it could not maintain minimum water pressure (See Coal Age, p. 24, February 2011).
Even with effective sprays, longwall mining generates float coal dust. With extensive floor heave, the longwall tailgate had low clearance. The bulk duster could not be used on the tailgate. Investigators found no evidence of rock dust applied in the tailgate after development.
A Workplace Run Amok
MSHA reviewed the training records for the two years prior to the explosion. Investigators found inadequate training or, in some cases, no training at all. A total of 263 employees and contractor files were reviewed. More than 200 training deficiencies were identified. More than 100 miners did not receive or did not complete required “experienced miner” training before commencing work at the UBB mine. More than 40 miners did not receive training before they were assigned to perform a new job task.
The mine provided illegal advance notice of MSHA inspectors. Security guards radioed the mine office when inspectors arrived. Dispatchers relayed the information underground and tracked the movements of MSHA inspectors. Production sections had at least one hour advanced noticed of inspections. “That would be plenty of time to correct non-compliant conditions or shut down production,” Strickland said. MSHA also believes the miners could increase the air flow in the areas to be inspected. Mine inspectors rarely arrived on the sections unannounced. Even with the advance notice, MSHA inspectors still issued more 104(d) orders at the UBB mine than any other coal mine in the year prior to the explosion.
The agency documented a work place fraught with intimidation. According to Strickland, UBB upper management threatened to fire first line management for not meeting production goals.
“Safety hazards such as insufficient air were not acceptable excuses for not running coal,” Strickland said. “A section foreman was fired for delaying production for about an hour to fix ventilation problems.”
Testimony indicated many miners were intimidated. According to the agency, they were strongly discouraged from slowing or stopping production for safety reasons. “Miners who were worried about conditions at the mine would not complain due to fear of retribution,” Strickland said. The miners at the UBB mine submitted only one underground hazard complaint since 2006.
The UBB mine lacked mine planning and engineering was performed on an ad hoc basis. There was no comprehensive mine plan. Instead management relied on trial and error. MSHA denied numerous plans. The agency documented excessive haste to speed up development for longwall mining. Pillars in the headgate and tailgate of the longwall, according to Strickland, were too small, creating extensive floor heave and numerous roof falls (and rib rolls), which restricted air flow in critical air courses. After two months of mining, subsidence cracks reached the overlying Logan’s Fork mine. A water inundation occurred, flooding the UBB bleeder system November 16, 2009. The mine suffered critical ventilation problems due to flooding, roof falls and floor heave.
Conclusions
MSHA said the evidence indicates the longwall shearer ignited methane liberated from floor cracks while cutting sandstone with worn bits and problems with the water sprays. A localized explosion occurred and traveled through the outby crosscut of the tailgate, putting coal dust into suspension before propagating into a major coal dust explosion.
Massey Energy believes the mine suffered a massive methane inundation. Strickland refutes that claim saying the floor heave brow in 1 North TG was excavated to a depth of 18 inches where the “crack” bottomed out in a layer of mottled shale, proving to be rootless.
The methane monitors in the longwall tailgate and on the shearer did not de-energize electrical power. Information collected from the handheld gas detector at shield 83 did not record elevated methane levels prior to the explosion. Information collected from handheld gas detectors carried by UBB miners who traveled to within two crosscuts of the longwall face on the tailgate side approximately two hours after the explosion recorded a methane level on only 0.3%.
On April 5, 2010, rescue team members advanced to shield 120 on the longwall face. They did not report any sound emanating from the longwall face or the tailgate entry which would have indicated a large volume of gas release. They also did not report elevated levels of methane along the longwall until reaching shield 120, where they reported 2.0% methane.
According to MSHA, several mine operator failures contributed to the explosion, including inadequate application of rock dust; inadequate control of float dust; missing and non-functional water sprays and insufficient water pressure on the longwall shearer; and an emphasis on productivity to the detriment of safety.
