57.22224—Auxiliary equipment stations (I-A and III mines).
Battery charging stations, compressor stations, pump stations, and transformer stations shall be installed in intake air at locations which are sufficiently ventilated to prevent the accumulation of methane.
If methane reaches 2.0 percent in the mine atmosphere, all persons other than competent persons necessary to make ventilation changes shall be withdrawn from affected areas until methane is reduced to less than 1.0 percent.
Code of Federal Regulations
(a)
Boreholes shall be drilled at least 25 feet in advance of a face whenever the work place is within—
(b)
Boreholes shall be drilled in such a manner to insure that the advancing face will not accidently break into an abandoned mine or abandoned working.