Massey Energy has long maintained that the 2010 disaster at the Massey-owned mine was caused by a massive release of methane gas, which would absolve them from responsibility.
According to the report released Thursday and commissioned by the state's former governor, a mining machine hit a rock, which created a spark and ignited a pocket of pent-up gas. The crew saw it and immediately shut down the machine, but the fireball moved and hit coal dust, which is extremely combustible. This caused a series of massive blasts that reached two miles through the mine and lasted for several minutes.
The investigation found that the company's ventilation system didn't work adequately, causing the deadly build-up of explosive gases. The report found that Massey Energy failed to meet federal and state safety standards for the handling of rock dust and that emergency water systems were not properly maintained and failed to function as they should have.
"This report tragically reinforces that the disaster that took the lives of 29 men at Upper Big Branch last year was absolutely preventable," Sen. Jay Rockefeller, D - W.Va., said in a statement today. "That will always be one of the most painful facts about this explosion."
"Twenty-nine coal miners paid with their lives for corporate risk-taking," J. Davitt McAteer wrote in the report. "[Massey Energy] broke faith with its workers by frequently and knowingly violating the laws and blatantly disregarding safety practices while creating a public perception that its operations exceeded industry safety standards."
Federal and state regulators are also criticized for "failing to use all the tools at their disposal," but Massey Energy gets the vast majority of the blame in the report.
Tragedy for a Mining Community
Of the miners who were killed, 19 died of carbon monoxide intoxication, while the 10 other miners were killed by the explosions.
Three layers of protection designed to safeguard the lives of miners failed at Upper Big Branch.
First, Massey's pre-shift/on-shift examination system broke down so that safety hazards either were not recorded, or, if recorded, were not corrected. Second, the U.S. Mine Safety and Health Administration failed to use all the tools at its disposal to ensure that the company was compliant with federal laws. Third, the West Virginia Office of Miners' Health Safety and Training failed in its role of enforcing state laws and serving as a watchdog for coal miners.
The deaths devastated the residents of Raleigh County, a mining community in West Virginia. The accident at the Upper Big Branch Mine was this country's worst mining disaster in 40 years.
For the families of the lost miners, the report will not bring solace, but may help them understand what happened on April 5, 2010, when fire erupted in the mine.
"There just ain't no peace out there right now. There just isn't," Charles Davis, 76, who lost his son Timmy, 51, and grandsons, Cory, 21, and Joshua, 27, in the accident, told ABC News.
"My boy, he was everything," he said in April while fighting back tears. "I can't look at the pictures. I can't say their names."
History of Neglect
Massey racked up more than 1,300 safety violations over the past five years, MSHA records show. Many were deemed willful or gross negligence.
And as recent as one month before the accident, records show inspectors cited the company for high levels of explosive dust, poor ventilation and flawed escape route plans at the Upper Big Branch facility.
"MSHA and state inspectors are also getting a lot of criticism over this and how things got so bad at that mine, because it didn't just happen overnight," said John Garretson, a retired federal mine inspector. "They've got to get stricter."
In a statement obtained by ABC News, Massey Energy disputes the findings of the report. "We disagree with Davitt's conclusion that this was an explosion fueled by coal dust," Massey Energy's General Counsel Shane Harvey old ABC News. "We believe that the explosion was caused by a massive inundation of methane-rich natural gas. Our experts feel confident that coal dust did not play an important role. Our experts continue to study the UBB explosion and our goal is to find answers and technologies that ultimately make mining safer."
Massey Energy is conducting its own investigation of the incident, but has yet to release its findings.
Many touched by the tragedy say they're not convinced regulators will take steps necessary to ensure it could never happen again.
"They just didn't take care of the mine right. They didn't ventilate it as they should. The inspectors were there too, and they didn't do anything," Davis said. "If they just keep up the laws they got, that's all they need. But they won't. It's all about money."
"Ultimately, the responsibility for the explosion at the Upper Big Branch mine lies with the management of Massey Energy. The company broke faith with its workers by frequently and knowingly violating the law and blatantly disregarding known safety practices while creating a public perception that its operations exceeded industry safety standards," the report stated.
It continued, "The story of Upper Big Branch is a cautionary tale of hubris. A company that was a towering presence in the Appalachian coalfields operated its mines in a profoundly reckless manner, and 29 coal miners paid with their lives for the corporate risk-taking. The April 5, 2010, explosion was not something that happened out of the blue, an event that could not have been anticipated or prevented. It was, to the contrary, a completely predictable result for a company that ignored basic safety standards and put too much faith in its own mythology."
ABC News' Devin Dwyer contributed to this report.