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Work far from over at flooded mine site

SOMERSET, Pennsylvania (CNN) -- The rescue of nine men at the Quecreek coal mine hasn't brought work at the southwestern Pennsylvania site to an end, authorities said Sunday.

CNN NewsPass Video    •  CNN's Jeff Flock visits an abandoned Pa. mine   •  Surveyor used GPS to locate miners   •  Rescued miners go home   •  Miners express appreciation  MORE STORIES   •  Pennsylvania panel to explore mining accident   •  Flooded mine could be idle for months   •  Pa. governor: Mine's operator 'owes answers'   •  A turning point in the rescue effort   •  Miners braved harrowing conditions   •  Previous mining accidents were minor » Story archive  RESOURCES   •  Jeff Goodell: Despair turns to joy   •  Gov. Schweiker: Mine probe to seek answers   •  Rescued miner: 'It was a team effort'   •  Why we burn coal  EXTRA INFORMATION   •  Gallery: The rescued miners   •  Gallery: Rescue quotes   •  Graphic: Diagram of the Quecreek Mine   •  Map: Mining accident   •  Timeline: What happened, and when

In addition to cleaning up, officials will investigate the cause of the accident, which apparently happened when the miners relied on a map that falsely showed an abandoned, water-filled tunnel farther away than it actually was.

Dave Hess, secretary of Pennsylvania's Department of Environmental Protection, told CNN the investigation would center on "what was wrong with the maps" and why.

The miners were digging in a coal mine named Quecreek Wednesday night when a wall separating their tunnel from an abandoned, flooded mine nearby gave way, sending millions of gallons of water roaring into Quecreek. The miners apparently thought they were hundreds of feet away from the older mine, when in fact they were right next to it.

"All over the country, and particularly here in Appalachia, there are a lot of old mine workings, a lot of old mines that have been sitting for many, many years, such as this one," said Dave Lauriski, director of the Mine and Safety Administration, which is part of the U.S. Labor Department. He said the older mine was abandoned in 1957.

Asked whether faulty maps were to blame, Lauriski said, "We have standards that are in place that are supposed to be followed when you approach old mines, approach old mine workings. ... We need to understand if those came into play here."

He said a team of investigators currently being assembled would conduct interviews, look at records, and crawl into the Quecreek mine once all the water has been pumped out to try to prevent such an accident from happening again.

Betsy Mallison of the DEP told CNN that workers would continue pumping out the water that rushed into Quecreek, which they estimated was about 50 million gallons.

Rescuers first pumped the water in an attempt to keep the levels down and protect the trapped miners. Once the water was down to a "comfortable" level, the actual rescue began, Mallison said.

"There's still water in that mine and there's still work to be done," she said. "And the reason for that is there's still equipment down there."

Officials haven't decided if they will permanently shut the Quecreek mine, but the rescue shaft that dug through 240 feet of earth and rock will be closed, using a process called "grouting," Mallison said.

"You just push a cement kind of substance down into the hole, and then you're done," she said.