MORGANTOWN — Separate accidents at two West Virginia coal operations Friday left one worker dead, two others injured and a fourth worker unaccounted for, according to company and state mine safety officials.

In North Central West Virginia, emergency officials were draining a coal slurry pond to search for a bulldozer operator who was unaccounted for after an embankment collapsed, sending three into the water.

U.S. Mine Safety and Health Administration spokeswoman Amy Louviere said a “massive failure” occurred around 12:15 p.m. Friday at the Nolans Run impoundment of Pennsylvania-based Consol Energy’s Robinson Run mine in Harrison County. One dozer operator and two engineers were on the platform when it collapsed.

Both engineers were rescued and were in non-critical condition.

Governor’s office spokeswoman Amy Shuler Goodwin said sonar detected an object in the pond and that officials were considering sending in divers. The water is about 12 feet deep.

MSHA personnel were on site, along with company, state and union officials.

Consol Energy spokeswoman Lynn Seay.said the cause of the failure was unclear.

Preparations plants wash raw coal to help it burn efficiently before it is shipped to customers. Coal slurry impoundments are used to contain both solid refuse and the wastewater byproduct known as slurry.

An electrician was killed when he became caught between a scoop and a continuous mining machine around 1:30 a.m. at the Pocahontas Mine A White Buck Portal near Rupert in Greenbrier County, said Leslie Fitzwater of the state Office of Miners’ Health Safety and Training.

The mine is owned by White Buck Coal Co., a subsidiary of Virginia-based Alpha Natural Resources. Alpha identified the victim as Steven O’Dell, 27, of Mount Nebo, an employee of its Alex Energy subsidiary.

O’Dell was pronounced dead at Greenbrier Valley Medical Center in Ronceverte.

“We are all saddened by the loss of a talented colleague and friend,” said Alex Energy President Craig Boggs.

State officials say O’Dell had three years of mining experience — two and a half at the Rupert mine.

O’Dell is the state’s sixth mining fatality this year.

The last death at the White Buck mine in Greenbrier County was on July 1, 2010, when 60-year-old electrician Wilbert Ray Starcher was run over by a piece of heavy equipment.

An MSHA accident report found the driver couldn’t see Starcher because someone had welded a piece of metal onto the vehicle that obscured his vision. The report says the mine’s owner at the time, Massey Energy, later removed the obstruction and trained miners to notify equipment operators before walking on the mine’s haulage road.

Alpha later bought Massey for $7.1 billion. It didn’t immediately comment on the latest accident.

White Buck Coal made news earlier this week when a former president, David C. Hughart, was charged with criminal conspiracy.

Hughart is cooperating with federal prosecutors in their continuing investigation of the Upper Big Branch mine disaster, an April 2010 explosion at another former Massey operation that killed 29 men. It was the worst U.S. mining disaster in four decades.

Prosecutors say Hughart worked with unnamed co-conspirators to ensure miners at White Buck and other, unidentified Massey-owned operations got advance warning about surprise federal inspections many times between 2000 and March 2010.

Those illegal warnings allegedly gave workers time to conceal life-threatening violations that could have led to citations, fines and costly shutdowns.

U.S. Attorney Booth Goodwin said Hughart is prepared to plead guilty to the charges, which carry the possibility of six years in prison. No hearing dates have been scheduled.