Magheracloone Mine Collapse

Its owner Gyproc Ireland says the recent transport and storage of water in an old part of the mine caused some underground pillars to collapse.

slowburner wrote: »

The 'underground pillars' are columns of bedrock that are left in place to support the roof of the mine (if that is your question). The mine is worked around them. Sometimes they need to be reinforced with 'cribbing' - usually timber.
Sometimes the pillars are mined out in a controlled manner to access the minerals above.

The lack of rain earlier last year saw the river Bursk shrink in volume, and in June, when the gypsum miners had to deal with a temporary excess of sulphate-laden water in one part of the mine (which they would normally do by pumping it into the river – safely and under Environmental Protection Agency licence), they channelled it instead into abandoned mine shafts, some 60m-70m underground.

They had done this before without adverse consequences, though not on this scale. Excess mine water is normally discharged into the river at a rate that does not cause environmental damage, but this can only be done when there is a sufficient volume of river water – an option not available last summer.

Within three months of the mine water being stored in the disused mine, several of the slender, 12m-high underground pillars holding up the disused tunnels collapsed, the mud foundations in which they sat weakened by the liquid.