(a) Abandoned workings that cannot be ventilated adequately with safety to employees must be sealed. The chief of the division will prescribe rules for sealing and periodic testing of air and water behind seals. Failure to comply with rules for sealing and periodic testing will be a violation of this section.
(b) Abandoned workings shall be posted to warn persons against entering, and all accessible abandoned workings shall be examined semimonthly or more often if necessary. When posting is inadequate to warn persons against entering, abandoned workings shall be properly fenced off at all such entrances.