CHARLESTON, W.Va. -- Methane gas may be bubbling into a flooded area of the Upper Big Branch mine where 29 men died in an explosion last April, a federal Mine Safety and Health Administration official said Wednesday.
Investigators have mapped about 90 percent of the Massey Energy mine, but up to six feet of water have kept them from searching two underground areas, said Kevin Stricklin, MSHA's administrator of coal mine safety and health. Both are lower than surrounding areas of the mine, which has about 12 miles of underground workings, and haven't been pumped out since the April 5 blast.
Investigators hope to begin draining the larger of the two areas area this week, a section known as Headgate 22. It has essentially been untouched since rescuers recovered nine bodies there in April.
"When you get up close to the face up there, you've got water bubbling," Stricklin said. The bubbles are probably methane, but Stricklin discounted their significance.
That said, Stricklin stressed the importance of entering the area to seek clues.
"We want to look at everything as a potential cause," he said. "We think it's important to visit Headgate 22."
MSHA also has not examined another flooded section about 1,000 feet away. That area also will be drained and examined, Stricklin said.
Officially the cause of the explosion hasn't been determined, but MSHA blamed methane and coal dust in a preliminary report to President Obama in April.
The agency's latest update signaled much remains to be done as part of the investigation.
MSHA said it has interviewed 197 witnesses, collected 260 pieces of evidence and taken more than 3,000 photographs. It also said that it has tested 1,800 dust samples to determine whether the mine was coated with explosive coal dust, among other things.
Still unfinished are tests of dust samples from the flooded sections, further mapping, about 50 interviews and testing of electrical equipment, MSHA said.
Investigators also plan to return as early as Wednesday to the mine's main production area to search for a missing remote control device for operating the longwall mining machine and to seek out more methane detectors.