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District 5 - Coal Mine Safety and Health
Hazard Alert - Hole-Throughs

Unintentional Hole-Throughs

Recent events at the Quecreek Mine in Pennsylvania have highlighted the need to remind everyone in the mining community of the dangers of mining near abandoned mine workings.

Accidental hole-throughs into abandoned mine works can be deadly to miners.   Unintentional hole-throughs into inaccessible mine workings can, without warning, release lethal amounts of water, methane, and/or blackdamp (carbon dioxide) into active mine workings.   Mines located in Virginia experience multiple unintentional hole-throughs each year.   Fortunately, no injuries have occurred, but there have been some close calls.

There are three major dangers associated with hole-throughs.   Inundation by water, often under pressure, can quickly flood an active section and cut off escape.   Inundation by explosive mixtures of methane, which can be pulled by ventilation, or forced by pressure out of old works across energized equipment.   Inundation by blackdamp (carbon dioxide) creates an irrespirable atmosphere by displacing oxygen as it is pulled by ventilation or forced by pressure out of old works across areas where miners are working.

Accurate surveying and mapping can virtually eliminate unintentional hole-throughs into abandoned or sealed areas.   Mine mapping must include all coal removed, including rooms and barrier cuts taken during second mining.   A relatively innocent barrier cut, if not mapped, can lead to an unintentional hole-through during mining of adjacent panels.   Unmapped mine workings that can be in excess of fifty years old also present a hazard.   Certified engineers and surveyors must make diligent searches for maps, old mine openings, and any available information regarding the location of old mine workings.   The Virginia Division of Mines, Minerals, and Energy maintains a map repository, which is available to interested parties.   Most mining companies and some property owners also maintain maps.   A short talk with an "old timer" has often revealed the existence of previously unknown works.   Careful engineering, through research and constant vigilance, are the best defense against accidental hole-throughs.   As a concerned industry, we must work together and utilize all available resources to prevent this potential killer from claiming one of our most precious resources, the miner.

Continuous Mining Machine