Massive Pillar Collapses in U.S. Underground Limestone …
a mining height of 25 to 30 ft, or 50% of the total height of the Loyalhanna Limestone Bedin the area of the collapse. Bench mining of the lower portion of the Loyalhanna was ongoing and conducted just four days prior to the pillar collapseIt was not evident if bench mining began recently or had been on. -going since development.
WhatsApp: +86 18221755073