UPDATE: Search continues for worker in coal slurry pondCHARLESTON, W.Va. -- One West Virginia coal miner was killed, two others were injured, and the search continued Friday night for a fourth miner, following incidents at an underground mine in Greenbrier County and a coal-slurry impoundment in Harrison County, mine safety regulators and company officials said. Early Friday, Steve O'Dell, 27, of Mount Nebo, was killed when he was pinned between a continuous mining machine and another piece of equipment called a scoop. That incident occurred at the Pocahontas Mine, an Alpha Natural Resources operation near Rupert.Then, shortly after noon, part of a coal-waste embankment gave way at Consol Energy's Robinson Run operation in Harrison County, sending a bulldozer and two pickup trucks sliding into the complex's huge slurry impoundment.Amy Louviere, a spokeswoman for the U.S. Mine Safety and Health Administration, called the Robinson Run incident a "massive failure" at the impoundment. She said the incident occurred at about 12:15 p.m."One dozer operator and two engineers were on top of the platform when the failure occurred," Louviere said.Lynn Seay, media relations director for Consol, said one employee was treated and released from a local hospital. A second employee was flown by medical helicopter to Ruby Memorial Hospital in Morgantown, where he was listed as stable. A third employee remains unaccounted for, Consol said."Today, four families were shaken by the unexpected but always present danger associated with mining," Gov. Earl Ray Tomblin said in a statement Friday night. "While we strive to ensure the safety of our coal miners, accidents do occur. Joanne and I pray for the miners and their families. We ask all West Virginians to do the same."Just before 5 p.m., rescue officials at Robinson Run who were using sonar found what they believed to be the missing bulldozer and developed plans for a dive team to explore the location, said Tomblin spokeswoman Amy Shuler Goodwin. But the team did not uncover the dozer and divers pulled out of that location just before 7 p.m., Goodwin said.Kathy Cosco, spokeswoman for the state Department of Environmental Protection, said the incident involved a "significant collapse" of a pad being built in the pool area of Consol's Nolan Run impoundment near Lumberport.Consol said that the embankment "remains unstable and continues to shift, creating difficult rescue conditions."However, Cosco said DEP engineers, in consultation with MSHA, "determined that no immediate risk of failure of the impoundment exists at this time and no evacuations are necessary or anticipated."The area of the pad that failed is about 200 yards long and 200 feet wide, Cosco said, and is about 1,000 feet away from the impoundment's main dam. Emergency response crews have been draining the impoundment using its existing dewatering system, which pumps into a nearby freshwater pond, where the material is filtered and treated before being discharged into Robinson Run.Cosco said that, on Thursday, Consol had been adding coarse refuse to the site to enlarge the impoundment as part of a plan approved by the DEP three years ago to expand the facility's ability to accept preparation plant waste.The DEP's most recent inspection of the 1,300-acre site, conducted on Oct. 16, revealed no violations, agency records show.Phil Smith, spokesman for the United Mine Workers union, said the two injured workers are salaried Consol employees, and the unaccounted-for miner a UMW member. Smith said bulldozers of this type typically would be equipped with two one-hour emergency breathing devices.In the Greenbrier County incident, O'Dell was an employee of Alpha's Alex Energy subsidiary working at the Pocahontas Mine near Rupert. The mine is operated by White Buck Coal Co. Alex Energy and White Buck are among the companies Alpha acquired in June 2011 when it purchased Massey Energy.Earlier this week, White Buck was in the news when federal prosecutors brought new charges against a former Massey executive who is cooperating in their investigation of the Upper Big Branch Mine Disaster.Five years ago, White Buck and two of its employees pleaded guilty to criminal mine-safety violations, but federal prosecutors at the time said the problems went no higher in the Massey corporate hierarchy. Now, prosecutors allege there was a broad conspiracy at White Buck and other Massey mines between 2000 and 2010, to violate safety rules and cover up the resulting dangerous conditions.MSHA chief Joe Main has warned that incidents where miners are crushed, run over, pinned by or struck by moving mining equipment are becoming all too common in underground mining. Since January 2010, at least 85 miners nationwide have been injured -- including eight who were killed -- in such incidents, MSHA has said.Still, the Obama administration has yet to finalize a proposed rule to require "proximity devices" that would shut down equipment when miners get too close, and help prevent such injuries and deaths.The White Buck death is the 18th U.S. coal-mining fatality in 2012, and the sixth in West Virginia.Staff writer Travis Crum contributed. Reach Ken Ward at firstname.lastname@example.org or 304-348-1702.