A contractor last night worked to contain a mine breakout that was discharging an estimated 4,000 gallons of water a minute onto the streets of McDonald, Washington County.

Darrell Sapp, Post-Gazette Water from an abandoned mine that burst during a leak inspection continues to flow through McDonald today at an estimated 10,000 gallons per minute, while the U.S. Office of Surface Mining was devising a way to divert the water from the streets. Workers continued to use sandbags to try and control the water's flow on Liberty Street. Click photo for larger image.

Doug Cooper, McDonald's assistant fire chief, said the contractor -- Specialized Professional Services Inc. of Chartiers -- was to dig a sump and pump the water through large-capacity hoses into Robinson Run, a tributary of Chartiers Creek, several blocks away. Cooper said state officials estimated it could take up to 27 days to stabilize the flow from the long-abandoned Nickle Plate Mine.

Cooper said emergency workers lifted an evacuation order for two of the families on Liberty Street living closest to the breakout . The order remained in effect for occupants of a duplex on Liberty Street until the building is inspected.

The breakout occurred Tuesday when workers, sent to check the source of water leaking onto Liberty Street, dug into the sidewalk and unleashed a torrent.

The Pittsburgh area is honeycombed with mines, some of them interconnected, and they gradually fill with water as rain falls and snow melts, said Bruce Leavitt, consulting hydrogeologist with West Virginia University's Hydrology Research Center.

When a mine or portion of a mine reaches capacity, the water must find a way out, Leavitt said. Sometimes, water seeps or flows into streams or down hillsides unnoticed; from time to time, it gushes out as happened in McDonald.

'This is part of our mining legacy," Leavitt said, noting old mines such as Nickle Plate, which operated from the late 1800s to the 1930s, weren't bound by modern regulations for mine water management.

Liberty Street sits above the McDonald business district, in a residential area that continues northward up a hill.

Nickle Plate already had been discharging into Robinson Run from a site on the other side of the hill, north of town, Leavitt said. He said he didn't know the volume of the discharge but was told it was sizable, enough to control the water level in the mine until Tuesday.

"Obviously, something has happened to change the way water is flowing in the mine," Leavitt said. Heavy rain in recent months may have pushed the water level beyond the original discharge's capacity, he said, or a section of mine roof could have collapsed and caused a backup of water.

Leavitt said the flow already appeared to have diminished from 10,000 gallons per minute to 4,000 gallons per minute. From the sidewalk, the water yesterday ran west along Liberty Street and south on North McDonald, wearing the streets before tumbling into Robinson Run.

Leavitt said the water was of "relatively poor" quality -- acidic, with iron and aluminum -- but may not have an appreciable effect on the already-polluted watershed.

Liberty, Sarah Street and part of North McDonald Street remained closed yesterday as water streamed downhill into the creek, and Mayor Jim Frazier said he feared freezing weather would turn pavement into sheets of ice.

Cooper said the pumping work would get water off the streets but force additional traffic restrictions because of the hoses snaking their way through town.

He said the work would eliminate or restrict traffic on Coal, Liberty, North McDonald, Sarah and School streets.

The state Department of Environmental Protection yesterday was selling subsidence insurance at the borough building, warning that rushing water could damage foundations and that mine workings weakened by the outflow could cause the ground and houses to settle.

The DEP offered immediate inspections to homeowners applying for the insurance and wrote policies for properties that appeared undamaged. Cooper said he was unaware of any homes with structural damage.