Rembco plugs a leaky mine
For a mine owner, groundwater is a constant concern – even after the mine is closed. That was the case for the owners of Black Wolf coal mine near Bluefield, West Virginia. As their federal lease neared its end, groundwater seepage from the mine was likely to interfere with the land reverting back to federal control. While the mine was still in operation, a temporary water removal system had kept the inflow under control. But now, the water was collecting in the tunnels…the removal system was overwhelmed…and the water was sheeting-out onto adjoining property. It was also seeping into the soil, moving underground, and re-emerging on adjacent property. Black Wolf called Rembco to stop the flow.
“The job was two-fold,” explains Rembco Project Manager, James Grubbs. “Black Wolf wanted us to stop the water migration. They also wanted us to seal the surface openings to stop water from escaping.” The two operations called for two different solutions.
First, to stop the below ground migration, Rembco used permeation grouting – performing a series of acrylamide injections to form an underground grout curtain. “This approach is ideal for containing underground water,” says Rembco General Superintendent, Tim Adkins. “Acrylamide solidifies into a gel in a very predictable manner. Once its gel time is reached, it forms a matrix of gel and soil that is impermeable to water. When mixed to achieve very short gel times, it will even perform in moving water”, adds Adkins. The grout curtain stopped the underground water migration, but sealing the surface openings required a different approach.
Shotcrete at the surface
Next, to cap the mine shaft openings, Rembco elected to seal the five surface openings with concrete. “If possible, we would have brought in ready mix ” says Grubbs, “but due to the remote location of the mine, that wasn’t a good option.” Fortunately, Rembco had just the right piece of equipment: a “dry shotcrete pot” that could easily be brought to the site. “The shotcrete pot uses a dry mix of sand and cement” Grubbs explains, “that allows us to stockpile materials on location and dry-mix them in a hopper. Water is then added at just the right ratio as the mixture is sprayed thru a nozzle onto the receiving surface.” This method worked just as planned and prevented further runoff from the mine shaft.
Signed, sealed, delivered
With the underground seepage stopped and the surface openings sealed, the project objectives were achieved. Black Wolf tamed. If you experience similar problems, we can help you tame those, too! Please give us a cal at 865-671-2925.