Page 294 - Safety Memo

• Repair and maintenance recognize hazards, and must have the authority to correct
• Tunnel renovations unsafe conditions and procedures subject to the TSOs.
Employees who are exposed to or control the exposure of 8406(f)
others to hyperbaric conditions shall be trained in hyperbaric- D. Diesel engines: Diesel engines are the only type of internal
related physics and physiology, recognition of pressure-related combustion engine acceptable for use during tunneling
injuries, and how to avoid discomfort during compression. operations, provided that the following requirements are met:
6075(c) 1. Cal/OSHA must issue a permit for diesel engine operation.
The Mining and Tunneling (M&T) Unit of Cal/OSHA enforces the 2. Conditions of the permit must be observed.
TSOs, which include:
3. Ventilation and fresh air flow must meet the required
A. Classifications: The M&T Unit is required to classify the gas minimum standards.
hazards of each tunnel or shaft. These classifications are:
8422 (a), (b) 4. Air concentrations of nitrogen dioxide, carbon monoxide,
and carbon dioxide in the tunnel must be determined at
1. Nongassy; least once during each shift at the peak of diesel operation
2. Potentially gassy; and kept at or below the PELs.
3. Gassy; and 5. A written record must be kept of the above readings.
4. Extra hazardous. 6. PELs of the above air contaminants or any other
contaminants must not be exceeded.
Note: The request for classification shall be sent to the
nearest M&T Unit office. 7. A certified gas tester must conduct the testing (see
additional requirements in 8470).
B. Pre-job safety conference: Before underground excavation
may begin, the M&T Unit must conduct an on-site, pre-job 8. An approved exhaust purifier must be installed and
safety conference with the project owner, the general maintained (see the requirements in 8470).
contractor, the tunnel contractor, and the tunnel contractor’s E. Materials, tools, and supplies being raised or lowered with a
employees. The goal of the conference is to ensure that all crane or hoist shall be secured or stacked to prevent the load
of the employees are aware of the conditions under which from shifting, snagging, or falling, as required in 8500.
the tunnel will be driven and that all of the safety issues are
discussed and problems resolved. 8408 F. Licensed blasters: All blasting at tunnel sites shall be carried
out or directly supervised onsite by a California licensed
C. Certified persons: Cal/OSHA requires the persons performing blaster as required by TSO 8560.
the duties of gas tester or safety representative to be certified
by passing a written and an oral examination administered by
the M&T Unit. 8406(f), (h) Welding, Cutting,
1. A certified gas tester is required for the following and Other Hot Work
operations:
a. After blasting operations Each year, numerous deaths from explosions, electrocutions,
b. Projects during which diesel equipment is used asphyxiation, falls, and crushing injuries are associated with
underground hot work activities. These deaths from hot work often occur
in confined or restricted spaces. In addition, numerous health
c. Hazardous underground gas conditions. 8406 hazards, including heavy metal poisoning, lung cancer, metal
2. A certified safety representative must direct the required fume fever, flash burns, and welders flash (burn to the eyes)
safety and health program and must be on-site while are associated with exposure to fumes, gases, and ionizing
employees are engaged in operations during which
the TSOs apply. The safety representative must have
knowledge in underground safety, must be able to

146 Cal/OSHA Pocket Guide for the Construction Industry | June 2019 Cal/OSHA Pocket Guide for the Construction Industry | June 2019 147