Highwall stability remains the major safety concern during highwall mining, with the Mine Safety and Health Administration requiring highwall mining operators to follow ground control plans that specify the pillar sizes necessary to prevent a pillar collapse that would threaten highwall stability.

NIOSH has developed the Analysis of Retreat Mining Pillar Stability-Highwall Mining (ARMPS-HWM) computer program to assist mine planners with pillar design.

Based on extensive research into instances of highwall mining pillar instability and pillar collapses in underground mines, ARMPS-HWM uses the Mark-Bieniawski formula to estimate the strength of long strip pillars.

The suggested design procedure addresses the following issues:

The number of holes between barrier pillars;

The size of the individual web pillars;

The size of the barrier pillars; and

The stability factor of the overall design.

NIOSH says the program is simple to install, easy to use and contains extensive "Help" files that provide more background on the research upon which design formulas are based. The Help files also contain suggestions for highwall mining through old auger holes and for close-proximity, multiple-split highwall mining.