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Tunnel and Shaft Construction
313
Section 23
Tunnel and Shaft Construction
This section sets forth requirements for tunnel and shaft construction. It covers the following
specific areas: General Requirements Emergency Provisions Ventilation Air Quality Dust Control Internal Combustion Engines Noise Control Fire Prevention and Control Excavation Operations Ground Support Transportation and Haulage Shafts Tunneling in Soil Compressed Air Work
23.1 General Requirements for Tunnel and Shaft Construction
In addition to complying with the safety requirements set forth in this section and other parts of
these standards, comply with applicable provisions of the contract when excavating and
constructing tunnels and shafts. Begin underground-related work only after an acceptable safety
program or a detailed supplementary submittal specific to underground operations has covered
all aspects of the operation.
23.1.1 Employee Identification. Entrances to all underground facilities must have a check-
in and checkout system that provides the contractor with an accurate record of each person
underground. The system must be able to identify each individual and general location.
General locations include heading, train crew, track crew, maintenance area, storage area,
survey stations, etc. Additionally, when underground, all employees must carry or wear a
positive means of identification, such as a metal disk or tag.
23.1.2 Illumination. Underground lighting and illumination intensities must adhere to the
current ANSI/IES RP-7, "Recommended Practice for Industrial Lighting" and UL 924,
"Emergency Lighting and Power Equipment." Use nonmetallic light fixtures and support
lighting conductors on insulators located on the side of the tunnel or shaft opposite the firing
line. Use acceptable portable lighting equipment within 50 feet of any underground heading
during explosives handling.
23.1.3 Electrical Equipment. A professional engineer (PE), knowledgeable in underground
wiring practices, must design and certify the underground electrical distribution system to
meet good practice and applicable standards. Install and maintain all electrical equipment,
including the section on "Electrical Safety," to meet applicable requirements. Permit only Reclamation Safety and Health Standards
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dry-type transformers underground and ensure they are protected from possible damage.
Separate or insulate power lines from air and waterlines, metal ducts, telephone lines, and
blasting lines.
23.1.4 Bonding and Grounding. Ground and bond air and water piping, metal vent
pipe, rails, and similar conductive devices at the portal or shaft head and at no more than
1,000-foot intervals.
23.1.5 Communications. Install a telephone system or an equivalent powered
communication system between the tunnel heading and the portal, the shaft bottom and shaft
head, and the first-aid station. Keep the powered communication systems independent of the
tunnel or shaft power supply, and install the powered communication systems so that failure
or disruption of any one station will not disrupt the operation of any other station. Test
communication systems at the beginning of each shift and more frequently, when necessary,
to ensure reliability. An employee must not work alone unless that employee is either within
voice communication distance of another employee or has an appropriate powered
communication system to obtain instructions and emergency assistance.
23.1.6 Blasting. Blasting and explosive-handling operations must conform to the
requirements in the "Blasting" section.
23.1.7 Personal Protective Equipment. Employees entering underground workings must
wear, as a minimum, hardhats, appropriate eye protection, and foot protection. Employees
entering wet areas must wear rubber footwear; underground type rain gear; and eye, face, and
head protection as described in the section on "Personal Protective Equipment." When
applicable, provide employees with other personal protective equipment, and ensure they
wear them.
23.2 Emergency Provisions
23.2.1 Evacuation Plan. Develop and post emergency evacuation plans, including
provisions for rescue equipment, at the portal or shaft head. Instruct employees in the
emergency procedures.
23.2.2 Self-Rescuers. Provide employees and others with self-rescuers, approved by
National Institute of Occupational Safety and Health (NIOSH) and/or Mine Safety and
Health Administration (MSHA), or make them available at headings, shaft bottoms, and all
other underground work areas. Provide at least one readily available self-rescuer for each
employee and visitor. Ensure that employees and others have satisfactorily completed
certified training before going underground. Visitors instructed in operating the self-rescuer
and accompanied by a trained employee are exempt from this training requirement. Maintain
self-rescuers in accordance with the manufacturers requirements. Section 23Tunnel and Shaft Construction
315
23.2.3 Emergency Hoists. Provide an emergency personnel hoist for shafts more than
50 feet deep. Design the hoist so that, as a minimum, the load hoist drum is powered in both
directions and a brake automatically applies upon power release or failure. Provide the
emergency hoist in addition to the primary hoist.
23.2.4 Rescue Crews. As part of the emergency plan required in the section on "Emergency
Planning," develop an emergency plan covering the possible emergencies requiring the use of
a rescue crew. The plan must include the equipment, training, and organization of the rescue
crews.
a. Provide at least two rescue crews of at least five men each for tunnel and shaft
operations employing 25 or more employees at one time underground. One crew must be
on the jobsite or within ½ hour travel time away from the portal. The other crew must be
within 2 hours travel time.
b. Organize and train at least one crew of at least five employees as a rescue crew, or, for
smaller jobs, arrange in advance with a locally available rescue service. Locate the rescue
crew or rescue service on the jobsite or within ½ hour travel time from the portal.
c. Thoroughly instruct new crew members upon assignment to the rescue crew and
conduct refresher training for the full crew at least every 6 months.
d. Instruct and train rescue team members to perform rescue operations; use and care for
oxygen breathing apparatus; and use firefighting equipment. Provide oxygen-breathing
apparatus unless, in the development of the emergency plan, analysis specifically
indicates that the use of self-contained breathing apparatus is sufficient. Keep breathing
apparatus in good repair and ready for use at all times. Maintain a sufficient supply of
spare breathing apparatus, replacement parts, and regenerating material or air cylinders.
23.2.5 Emergency Lighting. Provide each employee and visitor entering underground
workings with an MSHA-approved portable hand or cap lamp and make sure the employee or
visitor carries it. Providing hand or cap lamps does not take the place of meeting lighting
requirements.
23.2.6 Designated Person. At least one designated person must be on duty above ground
when personnel are underground. The designated person must be familiar with operating
features of the lighting and ventilation system and the procedures for obtaining emergency
service. The designee must remain within contact range of the communication system
annunciator. Reclamation Safety and Health Standards
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23.3 Requirements for Ventilation
Mechanically ventilate all areas of tunnels, shafts, and other underground workings with clean,
breathable, nonrecirculated, outside air. Place the ventilation system in operation before
employees enter any underground workings and keep the system in operation until all personnel
have left the area serviced by the system.
23.3.1 Ventilation System Design Requirements. Submit the system(s) design criteria,
specifications, and appropriate drawings before acquiring or installing the system.
Incorporate the following specific design features in all ventilation systems:
a. Mechanically induce all airflows. Do not provide required air quantities by natural
ventilation methods.
b. Construct primary ducts and fans of noncombustible metallic materials. You may use
short, noncritical sections of expandable-type ducting in secondary systems.
c. Use class 1, division 1 electric motors, fans, drives, and auxiliary equipment, including
wiring, starters, and controls. Design, install, and maintain the system in explosion-proof
condition and make sure it is capable of operating in an explosive atmosphere.
d. Ensure the noise levels of ventilation fans does not exceed 90 decibels when measured
at the closest point of employee exposure.
e. Ensure system airflows, secondary systems excepted, are reversible