Residents are happy it's quiet and dry on Liberty Street in McDonald, where a blowout Jan. 25 from the abandoned Nickle Plate Mine sent thousands of gallons of acidic water gushing through town.

Discharge from the mine has been diverted to a gravity drain built in a wooded area a half-mile outside of town.

The state Department of Environmental Protection yesterday unveiled what it called the permanent solution to the blowout from the 1930s-era mine that runs under the town at depths of 14 to 100 feet.

The gravity drain, which began full operation a week ago today, allowed DEP's emergency contractors to turn off loud diesel pumps that were used for more than two months to pull water out of the flooded mine void and channel it away from houses in the residential neighborhood where the blowout occurred. Cost of the project was $400,000.

The mine discharge now flows out of the drain and into Alexander Run, a tributary of Chartiers Creek.

"We selected the drain site because it had the least impact on the community," said Scott Horrell, DEP's Bureau of Abandoned Mine Reclamation program manager. "It also gives us additional room to treat the mine discharge."

Horrell said the initial blowout was triggered by heavy rains last fall associated with two big storms and a mine ceiling fall that diverted the underground mine pool's normal flow to the Liberty Street discharge.

The gravity drain, flowing at a rate of 1,200 gallons a minute, has reduced the elevation of the mine pool by more than six feet. DEP will continue to monitor the mine pool level under the town to make sure it doesn't rise again, or fall too low, which could exacerbate existing subsidence problems.

"We don't want to take all the water out because that will make the coal pillars that are under the homes in town weaker," said Robert Dolence, project engineer for Environmentally Innovative Solutions, DEP's contractor on the project.

Horrell said DEP is reviewing whether to inject grouting, made from coal ash, cement and sand, into the void under some houses to provide support. Several houses in McDonald have suffered damage.

Treatment of the mine discharge, which is acidic and contains iron, aluminum and manganese, will have to wait for funding.

There are at least eight larger deep mine discharges in the Chartiers Creek watershed.