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The hazards and visual impacts of abandoned mines are part of every day life in Maryland’s coal mining region. In the mountains of Western Maryland, along the banks of the North Branch of the Potomac River in Garrett County lies the town of Shallmar, a small community of approximately 100 residents. For decades, the residents of Shallmar have lived with the legacy of the coal mining industry that created the town long after the mines had closed.
The Wolf Den Coal Company began deep mining at Shallmar in 1919. Drainage from the mine was handled by gravity ditches and pumping. When all mining activities ceased in 1977, prior to enactment of federal mining and reclamation laws, the site was abandoned leaving many health, safety and environmental hazards. “After years of neglect, mining equipment, facilities and deep mine portals were in a state of deterioration and collapse, posing a hazard to local residents,” said John Carey, Director, Bureau of Mines for the area. “Something had to be done to protect the citizens of this county.”
Abandoned highwalls from strip mining were located near an existing road, posing a hazard to local residents and traffic. Nearly 300,000 cubic yards of coal refuse were dumped down slope of the mine openings resulting in a large, very steep, unstable and unvegetated piles, directly behind the residents.
Acid Run-off and Erosion Impacts
Following heavy rainfall events, erosion of the coal refuse bank impacted adjacent yards and structures with coal fines. On several occasions, starting in about 1995 the Maryland Department of the Environment, Bureau of Mines constructed ditches to protect houses and yards that had been damaged. Acid run-off and erosion from these piles also caused adverse environmental impacts to the North Branch of the Potomac River. The site had also become a convenient dumping ground for residential waste and created unsanitary conditions.
Degraded Water Quality
Acid mine drainage from the abandoned mine openings flowed unabated over the site. This affected natural drainways and degraded the water quality and aquatic biota of the North Branch of the Potomac River. The mine discharges low pH acid mine drainage, including dissolved metals and acidity.
Reclamation
The Bureau of Mines, Abandoned Mine Land Section developed a reclamation project, designed to eliminate the health, safety and environmental problems at the site in 1998. Several coal waste disposal alternatives, were considered, including on-site and off-site disposal in nearby abandoned surface mine pits. Reprocessing waste for coal recovery and transport to the Mount Storm Cogeneration Plant for use in electric generation were also considered. Based on coal recovery analyses and transportation costs, on-site disposal in the existing pits was determined the most cost-effective method of reclamation.
The Department of General Services performed the construction contracting and procurement with the Bureau of Mines as the Funding/Using Agency and the Architect/Engineer. The fund source for the project is from Maryland’s Abandoned Mine Land grant. Maryland currently receives $1.5 million annually from the federal Office of Surface Mining Reclamation Fund, which generates revenue from a 35-cent tax on coal production. Excavating Associates of Ellerslie, Md., was awarded the contract in June 2002, for the low bid amount of $1,114,687.
Acres Reclaimed
Project construction reclaimed 26 acres of abandoned deep mine support facilities and surface mine features, eliminating the public health, safety, and environmental hazards associated with the mine site. The highwall and hazardous water bodies were backfilled and regraded. The deep mine structures were demolished and mine portals sealed to prevent access. The abandoned coal refuse material was excavated and hauled to an on-site location for disposal and stabilization. On-site topsoil ‘borrow areas’ were developed to eliminate the costly need for importing soil. Excavating a large area of topsoil within the site and transporting it to coal refuse disposal areas.
Approximately 23,000 cubic yards of topsoil were salvaged, stockpiled and then spread to a minimum of six inches over the entire site. The lower limits of the project ran parallel to the back yards of many Shallmar residences. This made for tight constraints for sediment and erosion control diversion ditches and ponds. “Great care was taken to limit tree loss and intrusion into yards while providing adequate stormwater management and sediment/erosion controls for the project,” said Brad Nee, a MDE water resources design engineer.
An Acid Mine Drainage treatment “doser” was installed to treat mine drainage in May of 2005. A “doser” is a water-powered system that dispenses calcium oxide into the mine water neutralizing acidity and raising the pH. The site was also revegetated with a mixture of grasses, trees and shrubs to provide long-term stabilization and wildlife habitat. Construction began in June 2002 and was completed in the Spring 2003 for the final cost of $1,202,523. The doser was installed under a separate contract in the Summer 2005 at a cost of $125,750.
Update
The doser continues to treat mine drainage, and more than 6,000 trees have been planted to reforest the area.
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