Coal Mine Dewatering

Roger Howell and Vladimir Ugorets recently joined SRK (US) bringing with them significant experience in the fields of coal hydrogeology and coal mine dewatering. At the Skyline longwall coal mine in Utah, the two teamed up to determine the source of large, persistent groundwater inflows emanating from fracture intersections. Using forensic hydrology, geochemistry, and heuristic groundwater flow modeling, they showed that the origin of the inflows was within a thick stack of shoreface sandstones underlying estuarine and lagoonal coals and interbedded shales of the Cretaceous Blackhawk Formation.

The Skyline project included the installation of large diameter interception wells, modeling of existing hydrogeological conditions, and prediction of long term dewatering requirements for mine expansion. The project included a numerical assessment of the probable hydrologic consequences for surface resources resulting from the mine’s expansion.

At an open pit coal mine in the Powder River Basin, Wyoming, the problem was too little drainage of water from the channel and crevasse-splay sands and overbank mudstones, which lie over the coal seams. Groundwater in overburden was not draining ahead of mine advancement, and the residual moisture impeded excavation, caused combustion hazards in the coal, and left unstable working faces and spoil slopes. A program of field testing and groundwater modeling provided the necessary data to optimize the number and sequence of pumping wells in the coal, and to design a pattern of pumpless, passive drainwells to remove additional water from the overburden. The project included recommendations to significantly cut costs of drilling and well installation, monitoring and assessing the effects of nearby coal bed methane development, and the design of deep, large capacity water supply wells.
Other coal hydrogeology projects that Roger Howell and Vladimir Ugorets have directed include:

• An audit and risk analysis of a room and pillar mine in Colorado as part of due diligence for conversion to longwall mining
• Water chemistry and structural analyses to fingerprint the source of groundwater inflows, predict future inflow durations, and identify mitigation options for an Illinois mine
• Numerical modeling of dewatering requirements at a West Virginia mine, and assessment of the impacts of dewatering on local groundwater resources
• Development of a comprehensive Basin Water Management Plan for an extensive coal bed methane (CBM) development in
• Wyoming, including predicting the water chemistry in multiple mixing zones, and evaluating water disposal and mitigation options

Roger Howell: rhowell@srk.com
Vladimir Ugorets: vugorets@srk.com


 

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