CHARLESTON, W.Va.—An independent panel released a report Thursday blaming Massey Energy Co.'s disregard of safety standards and mining conditions in the explosion that killed 29 coal miners a year ago.

The report, produced by an independent team of investigators appointed by former West Virginia Gov. Joe Manchin, chronicled the events leading up to the deadly April 5, 2010, explosion in the Upper Big Branch mine.

Former federal mine safety chief, J. Davitt McAteer, who investigated previous mine disasters in West Virginia, led the Governor's Independent Investigation Panel, as it is formally known.

The panel's report blasted Richmond, Va.-based Massey for its worker safety standards as well as the Upper Big Branch mining conditions, stating that the coal company “exhibited a corporate mentality that placed the drive to produce coal above worker safety.”

“Ultimately, the responsibility for the explosion at the Upper Big Branch mine lies with the management of Massey Energy,” the 129-page report concluded. “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.”

A request for comment from Massey was not immediately returned.

All it took was a spark

In the days leading up to the disaster, miners complained of a lack of oxygen in the mine, according to the report. That plus a buildup of methane gas and coal dust was “perfect storm” that needed only a spark to “carry an explosion a long distance through the mine” and cause the disaster, according to the report.

That spark came shortly after 3 p.m. on April 5, 2010, just as the second shift began and the first-shift workers were exiting the mine. According to the report, a shearer cut into the sandstone roof, resulting in sparks that ignited a pocket of methane gas and created a fireball. The fireball ricocheted two miles throughout the mine, investigators found.

The result was the deadliest U.S. mining disaster in 40 years, according to published reports.

The report made several findings, including that Upper Big Branch disaster was a “man-made and could have been prevented had Massey Energy followed basic, well-tested and historically proven safety procedures.”

It also concluded that the mine explosion occurred due to the failure of three basic safety practices: a properly functioning ventilation system, adherence to federal and state rock-dusting standards, and proper maintenance of safety features on mine machinery.

Cautionary tale

“The story of Upper Big Branch is a cautionary tale of hubris,” the report said. “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 explosion “was not something that happened out of the blue, an event that could not have been anticipated or prevented,” the report went on. “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.”

The U.S. Department of Labor’s Mine Safety and Health Administration said in late March that it would hold a briefing on the Upper Big Branch mine explosion on June 29 to share with the public information that it gathered during its investigation.