(a) Guards. Excavations shall be provided with substantial barriers at points where passageways, tracks, roadways, or buildings adjoin such excavation.
(b) Loose material. All pit walls shall be kept free of unsafe loose materials. Hazardous areas shall be flagged, and no work shall be permitted in such areas.
(c) Scaling. Safe, acceptable methods shall be used for removing loose materials from the highwalls.
(d) Slope of material. Spoil piles shall be kept safely sloped to prevent loose material from sliding into the work area.
(e) Overburden. The area immediately above the highwall shall be cleared to a safe distance to prevent loose hazardous material from falling into the pit.