From a point where the seam is reached in the opening of an underground mine, to a point not exceeding a distance of four hundred feet therefrom, break-throughs shall be made between mine entries, where there are no rooms worked, not more than one hundred feet apart, provided such entries are not advanced beyond the point where the break-through will be made until the break-through is complete. Break-throughs between entries, except as provided in this section, shall be made not exceeding sixty feet apart. Where there is a solid block on one side of the room, break-throughs shall be made between such room and the adjacent room not to exceed sixty feet apart; where there is a breast or group of rooms, a break-through shall be made on one side or the other of each room, except the room adjoining the block not to exceed forty feet from the outside corner of the break-through to the nearest corner of the entrance to the room, and on the opposite side of the same room a break-through shall be made not to exceed eighty feet from the outside corner of the break-through to the nearest corner of the entrance to the room, and thereafter break-throughs shall be made not to exceed eighty feet apart on each side of the room. No working place, except those provided for within a distance of four hundred feet of the principal opening of a mine, shall be driven more than eighty feet in advance of a break-through or airway. The required air current shall be distributed to the working face of such entry or room. All break-throughs between entries, and when necessary between rooms, except the one nearest the working face, shall be closed and made airtight by brattice, trap doors, or other means, so that the current of air in circulation may sweep to the interior of the mine. Brattices between permanent inlet and outlet airways shall be constructed in a substantial manner of brick, masonry, concrete, or nonperishable material, provided that in hand-loading and nongaseous mines such brattices may be of wood. In mines generating firedamp, so as to be detected by a flame safety lamp, the air current shall be conducted by brattice, or other means, near enough to the working face to expel the firedamp, and prevent the accumulation of same. With the approval of the chief of the division of mineral resources management, a greater distance than specified in this section may be allowed between break-throughs. Any operator of a mine desiring to allow a greater distance between break-throughs than specified in this section shall file a written request to do so with the chief, together with a map of the mining and ventilating system for which approval and permission are asked, attached thereto, and the map shall become a part of the records in the office of the chief.

No operator of a mine shall refuse or neglect to comply with this section.

Effective Date: 06-14-2000.