Rainy Season Produces Sinkholes in Pittsburgh Area

Months of record-setting rains that caused an abandoned coal mine to burst forth with more than 200 million gallons of water are now causing a rash of mine-related sinkholes in southwestern Pennsylvania.

Four sinkholes have been reported in Pittsburgh and its suburbs, according to Betsy Mallison, spokeswoman for the state Department of Environmental Protection. One of them is four feet wide and about 12 feet deep, giving a clear view of an abandoned mine shaft and a ladder leading to it.

The holes are dangerous because people, especially children, sometimes explore them and could be trapped, overcome by poisonous gases or suffer from a lack of oxygen. Two children and a police officer who tried to help them were killed in such a hole in the late 1970s, said a federal mining official.

“It’s the weather. We see batches of these (sinkholes) after we get a real series of wet weather. It’s just the water moving through the ground,” Mallison said.

And it’s rarely been wetter in the region.

The National Weather Service says 68.88 inches of rain — 22.79 inches more than normal — fell at Pittsburgh International Airport from January 2004 through the end of last month. Last year was so rainy that the annual record of 50.61 inches set in 1890 was eclipsed by the end of October.

Most of the region’s towns are built on or near hills that once contained coal mines. When the ground is saturated with water, the old mines can cause three key problems, said Bill Ehler, an official with the federal Office of Surface Mining.

The land above shallow mines can open up with sinkholes. The land above deeper mines can sink, a phenomena known as subsidence that sometimes damages buildings. Finally, mines filled with decades of groundwater can burst forth suddenly if the ground is weakened.

“These problems are all related to a mine somehow,” Mallison said. “It’s a legacy of those years when people mined in their own back yards — and it’s made its way back up to the surface.”

On Jan. 25, the former entrance of an abandoned mine ruptured, sending more than 10,000 gallons of water a minute rushing down streets and across yards in McDonald, a small town about 10 miles west of Pittsburgh. Officials controlled the initial deluge by hiring a contractor to pump the acidic water into two large temporary pipes that emptied into a creek for about three weeks.

The water is still being pumped out at about 1,200 gallons a minute, Mallison said. The Department of Environmental Protection has hired an environmental contractor to study the problem and develop a permanent solution.

The Office of Surface Mining uses Abandoned Mine Reclamation Funds, which come from tonnage fees paid by mining companies, to fix sinkholes and to help pay for other damage, like the deluge in McDonald. It’s unclear how much longer it will be able to pay for such emergencies, however, because Congress hasn’t voted to continue the fund.

The program, which that has collected more than $7 billion in tonnage fees since it was created in 1978, was set to end June 30, but has been extended through Sept. 30 while Congress debates whether to end or change it, Ehler said.

Meanwhile, state and federal officials are bracing for more sinkholes, and hoping to avoid costly disasters. The McDonald mine flood caused about $375,000 damage to the city’s streets, sidewalks, curbs and storm drains, according to Mayor James Frazier.

“If it’s a shallow shaft and weathering hits it, maybe the extra rain we’ve had in the past year runs through that valley and weakens the rock,” Ehler said. “Basically, the ground wants to reach its lowest level and, if it’s unstable, that’s just what it does.”

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