Page 126 - Safety Memo

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

140 Cal/OSHA Pocket Guide for the Construction Industry | June 2015 Cal/OSHA Pocket Guide for the Construction Industry | June 2015 141