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SAFETY MANAGEMENT
What You Need to Know
about HEB Safety
By George Kennedy
Horizontal earth boring (HEB) is a trenchless method
used to install a pipe or a pipe casing in which other
utilities will eventually be inserted. The process involves
simultaneously jacking a pipe or pipe casing through
the earth while removing the spoil by means of a rotating auger.
Although boring operations have been used for decades and are
considered to be safe when performed properly, there are potential
hazards that must be addressed before and during the process.
Utility Damage Prevention
Before proceeding with any type of trenchless method, all
utilities crossing the center line of the bore or in the immediate
vicinity of the bore should be identified. Dig Safe call centers
should be notified at least 24 to 72 hours (check state One-Call
laws) prior to starting work. After the utilities are identified, it is
extremely important to determine the exact location and depth
of utilities that cross the bore path. Damaging a gas, electric or
water line can have serious consequences, including injuries to
workers and/or the public. Call before you dig!
Protective Systems
HEB requires the excavation of boring and receiving pits.
As with any excavation, precautions must be taken to ensure that
they will not cave in and bury a workers. In brief, HEB contractors
must comply with the same trenching and excavation
rules as open-cut contractors. OSHA and state regulations require
that protective systems be installed in the form of shoring,
trench boxes or sloping. They must be properly installed and
maintained. Additionally, there must be a Competent Person on
the job, and that person must ensure that the job remains safe as
it progresses by means of daily and as-needed inspections.
Fall Protection
Before a pit is dug, consideration should be given to ensuring
that no one will fall into it. Such a fall can result in serious
injuries, not only from the fall itself, but also from landing on
machinery, tools and/or materials that will eventually be in the
pit. Since OSHA Subpart M is not specific with regard to HEB
operations, contractors have some options.
It has, for example, been suggested that all pits should be
surrounded by a fence or barricades to keep unauthorized
108 Utility Contractor | May 2009
people away from excavation. If the pit is over 6 ft deep, some
form of fall protection system must be put in place to ensure
worker safety. The most reliable form of fall protection
is a guard rail system that surrounds the edge. Whether constructed
of wood, steel pipe, cables or other material, the system
must be able to support 200 lbs in an inward/downward
direction. The top rail or cable would have to be 42 in. ± 3 in.
above the ground with a midrail or barricade approximately
half way up. Cable systems should not deflect more than 3 in.
at any point.
A controlled access zone (CAZ) — an area where certain work
can take place without the use of a guardrail system — is another
option. However, before establishing a CAZ the contractor
must be able to demonstrate that it is infeasible or it creates
a greater hazard to use conventional fall protection equipment
such as guardrails, personal fall arrest system or motion stopping
system. The CAZ plan will have to be created by a qualified
person and supervised by Competent Persons who are
trained and knowledgeable about fall protection. Individuals
who are authorized to enter the CAZ must be identified in the
written plan, which should be jobsite-specific and available at
the jobsite.
Once a CAZ has been set up it must be surrounded by a
control line not less than 6 ft or more than 25 ft from the
unprotected edge of the pit. Control lines must be adequately
supported and flagged or otherwise clearly marked
at not more than 6-ft intervals. If authorized workers are
permitted inside the control lines, they must be trained
and assigned a Competent Person (with no other duties
to monitor).
Hazardous Atmosphere
The OSHA Excavation Standard–Subpart P states that
“every excavation where a hazardous atmosphere exists or
could reasonably be expected to exist” shall be tested and
monitored with an air monitor to prevent employee exposure
to a harmful atmosphere such as oxygen deficiency, explosive
methane or hydrogen sulfide. Boring pits, especially deep
ones, have the potential to contain a harmful atmosphere.
To avoid worker exposure to a hazardous atmosphere created
by these and other potential scenarios, it has been suggested