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Mine Pools

A century of extensive underground coal mining has resulted in many square miles of interconnected mine workings. After mine closure, the mine voids are allowed to fill with ground water creating a vast network of interconnected mine pools. 

Mine Pool Characterization Studies

OSMRE undertook site characterization studies of multiple mine-pools including developing and implementing a mine-pool monitoring program for each project to determine quantity, flow directions, quality, probable discharge locations and potential impacts.  These studies have extensive data sets collected over years, some for a decade, to better determine trends and account for short term deviations.

The hydrologic study of the Lancashire 15 mine-pool complex, located in Cambria County, Pennsylvania was conducted by the Office of Surface Mining Reclamation and Enforcement (OSMRE) and the Technical Services Group for the Pennsylvania Bureau of Abandoned Mined Lands (PA BAMR). The Lancashire 15 mine-pool complex is composed of 15 major underground mines and several smaller ones covering a total of about 12,000 acres.

The purpose of this study was to assess water quantity and quality issues associated with constructing a new pump and treat facility for the Lancashire 15 mine-pool. The new facility would replace an existing station, the Duman site, which is no longer cost efficient.

Brandy Camp is a small former coal mine (“Patch”) town approximately nine miles north east of Brockway along State Route 219. The Brandy Camp discharge point is located approximately 1000 feet south-southeast of the town. This study is the culmination of the hydrogeologic characterization of underground and surface mines that are hydrologically connected to the discharge located adjacent to the Brandy Camp treatment facilities.

Shortly after the Brandy Camp treatment plant was completed and operational, it was determined to be significantly undersized. On the average, the plant was capable of treating slightly more than one half of the mine water discharge quality. During high-flow conditions, the plant treats well less than 50% of the mine discharge. Therefore, the first question to be answered is why were the baseline (background) discharge measurements much lower than those recorded since the plant came online. These baseline discharge measurements caused the plant to be under sized. The second task of this project was to determine potential locations within the hydrologically-connected underground mines for the injection of iron sludge produced at the plant by the belt press and settling ponds.

The Monongahela River is a major drainage basin including over 7,300 square miles in portions of West Virginia, Maryland, and Pennsylvania. It supports sport fishing, recreational boating, commercial navigation, and is a source of water for numerous municipalities. The Office of Surface Mining Reclamation and Enforcement (OSMRE) has completed a hydrologic assessment of the Fairmont Mine Pool  that assesses the potential risk to the Monongahela River in West Virginia from polluting discharges that could emanate from flooding active or abandoned underground mining operations. 

The “Fairmont Pool” is a geologically isolated series of eight large and several smaller flooded underground mines across 52,000 acres. The mine complex is located on the west side of the Monongahela River.  The study focused on the abandoned, closed and active underground mines that comprise and interact directly with this pool. The hydrologic assessment determined that at present the pool is essentially in steady-state conditions with the water elevation being maintained and discharge water being treated to effluent standards by industry.

There has been and currently are significant underground mining activities within the headwaters of the North Branch Potomac River which spans both the Maryland and West Virginia state line. These activities have a potential for significant current and future hydrologic impacts to the river. The North Branch Potomac River Mine Pool Assessment study encompasses 12 underground coal mines that underlie the head waters of the North Branch of Potomac River Watershed and span across more than 25,000 acres in both Maryland and West Virginia. A combination of abandoned, active and inactive underground mines is located within the study area. The study and resultant report was performed by the Office of Surface Mining and Reclamation and Enforcement at the request of the Maryland Department of the Environment, Bureau of Mines and in cooperation West Virginia Department of Environmental Protection.

An assessment of the current conditions of the underground mine workings in addition to a determination of the potential for discharges resulting from the flooding of these workings are the main subjects of the report. Risks to the North Branch of the Potomac River posed by the current and potential future hydrologic conditions were also addressed.

Currently all of the mines have pools being managed by either mine operators or a state agency with no known pollutional discharges. The future predictions indicate that managing the mine pool levels at an elevation below the river is critical in the protection of the North Branch Potomac River. Without water management, all existing mine pools located in both West Virginia and Maryland have the potential to either increase the flow through leakage between various mines or directly leak and/or discharge to the river.