In any tunnel classified as gassy by the division, there shall be tests for gas or vapors taken prior to each shift and at least hourly during actual operation. If a mechanical excavator is used, gas tests shall be made prior to removal of muck or material and before any cutting or drilling in tunnels or underground mines where explosives are used. A log shall be maintained for inspection by the division showing results of each test. Whenever a tunnel excavation or underground mine operation approaches a geologic formation in which there is a likelihood of encountering gas or water, a probe hole at least 20 feet ahead of the tunnel face or area where material is being mined shall be maintained.

(Added by Stats. 1972, Ch. 1430.)

Terms Used In California Labor Code 7966

  • Division: means the Division of Occupational Safety and Health. See California Labor Code 7951
  • Face: means the head of the tunnel where soil is being removed, or that area in a mine where digging is underway. See California Labor Code 7951
  • Mine: means any excavation or opening above or below ground used for removal of ore, minerals, gravel, sand, rock, or other materials intended for manufacturing or sale. See California Labor Code 7951
  • Muck: means excavated dirt, rock, or other material. See California Labor Code 7951
  • Tunnel: means an underground passageway, excavated by men and equipment working below the earth's surface, that provides a subterranean route along which men, equipment, or substances can move. See California Labor Code 7951
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