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Maps of old mines often off the mark

Going underground a risky business

Saturday, July 27, 2002

By Steve Levin, Post-Gazette Staff Writer

In coal mining regions of Pennsylvania and the rest of the country, engineers and surveyors draw maps to chart the course of coal excavations hundreds of feet below the surface. These to-scale maps are developed based on research and readings, and on previously drawn maps of the area.

Newer maps are accurate to within centimeters. The mining company uses them to find valuable seams of coal; mine workers depend on them for their lives.

The older maps, some drawn as long as 60 years ago and based on sometimes rough calculations, are supposed to provide details of nearby abandoned mines, contour lines of all elevations and adjacent mine workings within 1,000 feet, along with any water pools above.

But not all of them do.

As the inundation Wednesday night at Quecreek Mine in Somerset County showed, a mapping mistake can suddenly leave miners isolated and fighting for their lives hundreds of feet below the ground.

In the case of Quecreek Mine, a precise location for an abandoned mine nearby didn't appear on the company's map.When mine workers accidentally breached the adjacent Saxman Mine, an estimated 60 million gallons of water flooded Quecreek Mine, trapping nine miners in a 4-foot-high air pocket.

"Mine workers usually accept the fact that when management says conditions are OK, they will accept it," said Raj Ramani, a Penn State University professor emeritus of mining engineering. "There is an element of faith. When told, 'These are your working places today and here is where you will cut coal,' they will do it."

Robert Scott, president of PBS Coals Inc., a small coal mining company in Somerset County, said that the blame for the flood at Quecreek lay with the old maps.

"What happened here appears to be that someone was way off -- not in the current mine but in the old one," said Scott. "In this case, no one perceived a risk. The other mine shouldn't have been there. It was mapped but it wasn't extended into that area."

PBS Coals Inc. and Rox Coal Inc. are owned by Mincorp Inc., a privately held company that is one of Somerset County's largest mining operations.

Mincorp spokesman Tim Phillips described Quecreek Mine's owner, Blackwolf Coal Co., as a separate company that supplies Mincorp with coal under contract.

Blackwolf's president, David Rebuck, is a former president of Rox Coal. Phillips said Rebuck, who has declined to comment about the accident, left Rox two years ago to start the new company.

Quecreek Mine produces about 15,780 tons of coal per month, much smaller than PBS, which Scott said produces about 208,000 tons per month. Both are considered small mines, however, when compared with mining operations that produce six million tons or more of coal annually.

Small mines such as Quecreek, which opened in 2000, usually have production life spans of less than 10 years, while a large mine may continue for more than 25 years.

No matter a mine's size, it is required to follow a rigid set of federal and state guidelines. The major difference, according to Mark Radomsky, director of field service for Penn State University's Miner Training Program, is that a larger mine may have more financial capital available for equipment. But, he said, it doesn't mean the quality of equipment at smaller mines is inferior.

However, according to Larry Grayson, chair of mining engineering at the University of Missouri-Rolla, small mines often have fatality rates three to five times higher than larger mines. Earlier this year, Dave D. Lauriski, assistant secretary of labor for mine safety and health, called for "special attention" to be paid to the needs of small mines, including safety.

While expensive equipment is available that may have alerted mine workers in Quecreek Mine of the adjacent flooded mine, few coal companies utilize such tools.

There are reasons for that, said Mike Batzle, a geophysicist at the Colorado School of Mines.

One such tool, a gravimeter, can detect underground cavities by providing precise gravity measurements from above ground. But it only works up to a depth of about 10 or 12 yards, Batzle said.

Ground-penetrating radar uses electromagnetic waves that "bounce" back, providing a reading of voids or solid ground. But if the radar waves hit any material with conductivity such as water or clay, they are "swallowed up," Batzle said, and thus not usable.

Seismic readings, however, are often used on coal seams. The data is interpreted to determine the location of faults, fractures and voids.

Ed Blott, a consultant with the Littleton, Colo., company ExplorTech, does work on coal mines in New Mexico, Wyoming and Colorado. He said acquiring seismic equipment is expensive and therefore out of the reach of small mines.

A two-dimensional seismic profiling of one mile of a mine costs about $10,000, Blott said. For a small mine such as Quecreek, he estimated the cost of seismic profiling could exceed $80,000 for a two-dimensional grid of coverage detailed enough to identify faults and voids.

"For a mine not taking out more than a few hundred tons of coal compared to the cost of seismic profiling, they can't really afford the cost and it may be imprudent for them to spend that kind of money," Blott said.

That leaves one option for mine workers, and it is the one most commonly used. If concerned about the proximity of a void or abandoned mine, they drill a small exploratory hole, as long as 30 feet but less than 2 inches in diameter, as a probe. It tells them immediately whether the features on their map are accurate, and can be stopped up quickly if water starts coming through.

"Maps can provide a false sense of security," said Jim Dean, director of Mining Extension Service at West Virginia University's College of Engineering and Mineral Resources.

D.J. Johnson, vice president of the United States Mine Rescue Association, went further.

"If we admit that [mining maps] are that inaccurate, we have to deal with it," he said.

Staff writer Jim McKay contributed to this report.

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