SAFE TY BY TOM O’CONNOR
First, it is important to understand
that an excavation is a manmade trench,
cut, cavity or depression in the ground
that is formed by earth removal. Typically, when working in this environment,
a person could encounter three major
risk factors: cave-ins, confined space hazards and underground utilities.
Fortunately, some basic safety protocols can help prevent accidents. One of
the first OSHA-required precautions is
that there must always be a “competent
person” on hand and available throughout
the excavation process. A competent person is someone who is able to identify the
hazards and dangerous work conditions
and take action or corrective measures to
eliminate those hazards.
It is important to ensure that an excavation area is properly marked. Contact
the work site’s property owners and relevant utilities to ensure that this marking
has been done. Most states require a minimum of 24–48 hours to clear and mark an
area before commencing work.
Prior to beginning an excavation
operation, workers should know what
each marking on the work site indicates.
Utilities usually use the following colors
as markings for identification purposes:
white (proposed excavation); pink (
temporary survey markings); red (electric
lines and lighting cables); yellow (gas,
oil, petroleum and steam lines); orange
(communication lines, cables or alarm
signals); blue (water); purple (reclaimed
water or irrigation lines); and green
(sewer and drain lines).
When using machinery to excavate an
area, it is imperative to ensure that there
is no risk of coming into contact with any
underground utility. If excavation opera-
tions are performed near underground
utilities, hand digging or sucker vacuums
should be used. This especially holds true
when digging within 5 feet of energized
lines or equipment. Spoil piles should
always be a minimum of 2 feet from the
edge of the excavation.
In the event that a gas line is struck
when digging, work should be stopped
immediately. The area should be cleared,
and the gas company, the public, and
police and fire department should be
notified. It is not safe to attempt to fill in
The gas should be allowed to dissipate
into the atmosphere, and all equipment
and devices that may ignite the leak or
cause an explosion should be shut down.
This includes vehicles and even two-way
radios. If the leak is on fire, let it burn.
If a fiber optic cable is struck or cut,
do not look directly at the cut. The light
can damage eyesight. Contact the communication company as soon as possible.
If a water or sewer line is struck, contact
the appropriate utility immediately.
When an excavation is greater than
5 feet deep, the sides must be shored or
sloped. The sloping and benching sys-
tems must be stable enough to protect
workers in the excavation. According
to OSHA’s Trenching and Excavating
Fact Sheet, there are several different
protective systems. They are as follows:
“Benching means a method of protecting
workers from cave-ins by excavating the
sides of an excavation to form one or a
series of horizontal levels or steps, usu-
ally with vertical or near vertical surfaces
between levels. Benching cannot be done
in Type C soil [the least stable].
“Sloping involves cutting back the
trench wall at an angle inclined away
from the excavation.
“Shoring requires installing alumi-
num hydraulic or other types of support
to prevent soil movement and cave-ins.
“Shielding protects workers by using
trench boxes or other types of supports to
prevent soil cave-ins.”
Understanding the different types of
soil and familiarizing workers with addi-
tional required protective systems can
also be helpful in preventing accidents.
Excavations greater than 4 feet deep
must have a safe means of exit. This may
include a ladder or stepladder as an escape
option. A ladder must extend 3 feet above
When working in an excavation, it
is never safe to travel more than 25 feet
laterally to get out of the work area. Any
distance greater than that would be far too
risky for potential cave-ins.
Upon completion of the dig, the excavation area should be filled in as much
as possible. If any portion remains open,
barriers must be in place to protect site
workers and the public. Barriers may
include lighted warning devices, rope
barriers, wood barricades or guardrails.
Following these basic safety strate-
gies can reduce the risk of injury or death
when working in or around excavating
and trenching operations. For more
information, visit www.osha.gov.
Excavating and Trenching
How to avoid underground hazards
ACCORDING TO THE U.S. BUREAU OF LABOR STATISTICS, more than 50 workers
die annually in excavation and trenching accidents. Though most electricians are not
directly involved in excavating operations, electrical workers may get involved when
completing underground line work. As a result, the Occupational Safety and Health
Administration (OSHA) has some specific guidelines for this type of work.
O’CONNOR is safety and regulatory affairs manager for Intec, a safety consulting, training and
publishing firm that offers on-site assistance and produces manuals, training videos and software
for contractors. He has significant experience working with national and international trade
associations with an expertise in government affairs. Reach him at firstname.lastname@example.org. TH