30 CFR 57.20021 - Abandoned mine openings.
Upon abandonment of a mine, the owner or operator shall effectively close or fence off all surface openings down which persons could fall or through which persons could enter. Upon or near all such safeguards, trespass warnings and appropriate danger notices shall be posted.
Title 30 published on 2014-07-01.
No entries appear in the Federal Register after this date, for 30 CFR Part 57.