30 CFR § 75.334
Worked-out areas and areas where pillars are being recovered.
(a) Worked-out areas where no pillars have been recovered shall be--
(1) Ventilated so that methane-air mixtures and other gases, dusts,
and fumes from throughout the worked-out areas are continuously diluted and
routed into a return air course or to the surface of the mine; or
(b)(1) During pillar recovery a bleeder system shall be used to control
the air passing through the area and to continuously dilute and move
methane-air mixtures and other gases, dusts, and fumes from the worked-out
area away from active workings and into a return air course or to the
surface of the mine.
(2) After pillar recovery a bleeder system shall be maintained to
provide ventilation to the worked-out area, or the area shall be sealed.
(c) The approved ventilation plan shall specify the following:
(1) The design and use of bleeder systems;
(2) The means to determine the effectiveness of bleeder systems;
(3) The means for adequately maintaining bleeder entries free of
obstructions such as roof falls and standing water; and
(4) The location of ventilating devices such as regulators, stoppings
and bleeder connectors used to control air movement through the worked-out
(d) If the bleeder system used does not continuously dilute and move
methane-air mixtures and other gases, dusts, and fumes away from worked-out
areas into a return air course or to the surface of the mine, or it cannot be
determined by examinations or evaluations under §75.364
that the bleeder system is working effectively, the worked-out
area shall be sealed.
(e) Each mining system shall be designed so that each worked-out area can
be sealed. The approved ventilation plan shall specify the location and the
sequence of construction of proposed seals.
(f) In place of the requirements of paragraphs (a) and (b) of this
section, for mines with a demonstrated history of spontaneous combustion, or
that are located in a coal seam determined to be susceptible to spontaneous
combustion, the approved ventilation plan shall specify the following:
(1) Measures to detect methane, carbon monoxide, and oxygen
concentrations during and after pillar recovery, and in worked-out areas
where no pillars have been recovered, to determine if the areas must be
ventilated or sealed.
(2) Actions that will be taken to protect miners from the hazards of
(3) If a bleeder system will not be used, the methods that will be
used to control spontaneous combustion, accumulations of methane-air
mixtures, and other gases, dusts, and fumes in the worked-out area.