Section 57.4131 - Surface fan installations and mine openings(a) On the surface, no more than one day's supply of combustible materials shall be stored within 100 feet of mine openings or within 100 feet of fan installations used for underground ventilation.(b) the one-day supply shall be kept at least 25 feet away from any mine opening except during transit into the mine.(c) Dry vegetation shall not be permitted within 25 feet of mine openings.