MSHA issued a specific warning about highwalls because winter months can bring drastic changes to their stability due to freezing and thawing. Water accumulates in crevices of rocks and then freezes. The ice acts as a wedge to expand the crevice opening. The ice thaws and the cycle begins again which in turn compromises the stability of the highwall that can result in highwall failure.
BEST PRACTICES
• Conduct examinations of the highwall before, during and after every rain, freeze, or thaw.
• Scale down loose hazardous material.
• Do not work under loose material for any reason.
• Pay special attention when working in the corners of box cuts.
• Increase the number of benches at each highwall to catch falling material.
• Use CB radios to keep equipment operators informed of highwall conditions.
REMEMBER: Safety depends you!