WASHINGTON, May 20 (UPI) -- A final report on West Virginia's Upper Big Branch coal mine disaster blames operator Massey Energy for the explosion last April that claimed the lives of 29 men.

The investigation was led by J. Davitt McAteer, who served as the assistant secretary for the U.S. Labor Department's Mine Safety and Health Administration during the Clinton administration.


"Ultimately, the responsibility for the explosion at the Upper Big Branch mine lies with the management of Massey Energy," the report says of the worst American mining disaster in 40 years.

"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 standards."

The 120-page report says the disaster was the result of failures of three "basic safety practices," including "a properly functioning ventilating system, adherence to federal and state rock dusting standards; and proper maintenance of safety features on mine machinery."

Rock dusting standards are intended to keep explosive coal dust under control.

Combustible coal dust had been permitted to accumulate, the report says, adding that a crew of two was responsible for removing dust from the 2.7-mile mine on a part-time basis and that dusting equipment was outdated and poorly maintained, The Wall Street Journal reports.

The report says workers had requested rock dusting 561 times in the 26 days before the disaster, but the dusting had been done only 65 times.

Had there not been so much coal dust, the report says, the explosion "might well have been contained to the longwall area" and not have killed some miners more than a mile away. A series of explosions rocketed through the mine, rather than one massive blast as was initially believed.

But in a statement released Thursday, Massey said it believes "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," the statement said, saying the experts continue to study the explosion, "and our goal is to find answers and technologies that ultimately make mining safer."

"The story of Upper Big Branch is a cautionary tale of hubris," the report concludes. "A company that was a towering presence in the Appalachian coal fields operated its mines in a profoundly reckless manner, and 29 coal miners paid with their lives for the corporate risk taking."