Trenching is a Dangerous and Dirty Business |
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Jim Boom
OSHA
Tragically, every
year workers continue to lose their lives from trench or excavation cave-ins
What is even more tragic is that virtually all of the cave-in fatalities
could have been prevented by following OSHA's excavation standard.1
Newspaper articles reporting these tragedies are often accompanied by
photos of coworkers or fire department rescue teams attempting to rescue
the victims, sometimes placing the would-be rescuers in danger as well.
These accidents happen because persons responsible for providing a safe
workplace choose to ignore well-known safety requirements for trenches
and excavations.
Trenching and excavating
work is dangerous. In 1998, 33 workers lost their lives while doing excavation
work, with cave-ins accounting for nearly 70 percent, or 23, of the fatalities.2
Five deaths resulted from employee contact with backhoe buckets within
an excavation. The remaining fatalities were due to electrocution and
crushing incidents from dropped loads and/or equipment rollovers into
an excavation.
1
U.S. Department of Labor, Occupational Safety and Health Administration,
Title 29 of the Code of Federal Regulations (CFR), Part 1926, Subpart P.
2 Based on OSHA's Integrated Management Information System (IMIS)
data base for Fiscal Year 1998 (Federal Only).
In light of OSHA's strong enforcement since the beginning of its special
emphasis program 3 in 1985, these fatality numbers are perplexing
for anyone in the safety business. For example, from October 1997 through
September 1998, the number of excavation inspections accounted for 8.2 percent
4 of the total number of all construction inspections conducted
in that year. The total amount of penalty proposed for excavation violations,
however, represents 21 percent 5 of the total penalties for all
construction violations. In 1998, two out of the top 10 violations cited
for all of the construction industry were for excavations.6
3
Special Emphasis Programs allow programmed inspections where there is a
potential for high hazards resulting in injuries or illnesses. A programmed
inspection targets a specific industry and related safety and health hazards.
In the case of trenching, OSHA inspectors focus on trenching and excavating
activities and their associated hazards to help prevent accidents and injuries.
See also OSHA Compliance Directive CPL 2.69, Special Emphasis: Trenching
and Excavation, September 19, 1985. Available on OSHA's website at www.osha.gov
under Compliance Directives and Regulations and Compliance. 4
OSHA IMIS data base Fiscal Year 1998 (Federal Only).
5 Ibid.
6 Ibid.
The weight of soil
sloughing off the side of an unprotected trench can cause a crushing blow
to an employee on the bottom, resulting in a serious injury or fatality.
The financial consequences for an employer knowingly exposing employees
to unprotected trenches and violating the excavation standard also can
be devastating to a company or corporation. Construction is one of five
high-hazard industries OSHA is targeting to reduce injuries and illnesses.7
During Fiscal Year 1999, OSHA's Directorate of Construction reviewed more
than 70 construction inspection cases each with proposed monetary penalties
in excess $100,000. Thirty percent of the cases reviewed involved contractors
that allegedly violated the excavation standard.
7 See OSHA's
Strategic Plan for 1997-2002, dated September 18, 1998, under About OSHA
at www.osha.gov.
"In 1998, 33 workers lost their lives while doing excavation work,
with cave-ins accounting for nearly 70 percent, or 23, of the fatalities."
"This construction
site has inadequate sloping, no shoring or trench shield, no safe egress,
improper use of ladders, and cluttered walking and working surfaces. These
hazards expose employees to potential broken bones and severe lacerations
from slips, trips, and falls and to serious injuries or death from being
crushed or suffocated from a cave-in."
Preventing Accidents in
Excavations
What can be done to
help prevent these tragic accidents? Key to prevention is the employer's
leadership and commitment to a good safety and health program. Moreover,
a crucial player in excavation safety is the company's designated competent
person. "Competent person" is more than a title. OSHA defines a competent
person as one who is capable of identifying existing and predictable hazards
or working conditions that are hazardous, unsanitary, or dangerous to
employees, and who also has authorization to take prompt corrective measures
to eliminate or control these hazards and conditions. A designated person
who is unfamiliar with the excavation requirements, who is unable to recognize
hazards, or who doesn't have the authority to make corrective measures
may miss a life-threatening condition.
A "competent person" knows the requirements of the excavation standard
and his or her safety role. The competent person is responsible for analyzing
and classifying soil; selecting and installing appropriate protective
systems; placing spoil piles; providing safe egress; determining the appropriate
proximity of equipment or traffic that could cause vibrations to excavation
walls; being aware of changes in weather, water, or other conditions that
may increase the risk of a cave in; and assessing dangerous atmospheres,
water seepage, underground utilities, adjacent structures, dangerous work
practices, deficiencies in protective systems, and much more.
How Much Dirt Is Too Much?
Training employees
to recognize excavation hazards is very important. When OSHA compliance
officers inspect unprotected trenches, they often find that employees
who are exposed to the danger of cave-ins have not been adequately trained
to recognize the hazards in their work environment. Sometimes workers
don't realize how much dirt weighs and that a small amount of soil sloughing
off in an unprotected trench can injure them.
"During Fiscal
Year 1999, OSHA's Directorate of Construction reviewed more than 70 construction
inspection cases each with proposed monetary penalties in excess of $100,000."
"One cubic
yard of soil can weigh 2,700 pounds or more. That's only 85 pounds lighter
than a new Volkswagen Beetle."
As a training exercise,
one can stress the weight of soil by comparing it to things people can
relate to. For example, 1 cubic foot of soil can weigh 100 pounds or more.
Compare the weight of a cubic foot bag of concrete mix to a cubic foot
of soil. The concrete mix usually weighs about 60 pounds. A chunk of earth
the size of a washing machine can weigh 1,500 pounds or more. One cubic
yard of soil can weigh 2,700 pounds or more. That's only 85 pounds lighter
than a new Volkswagen Beetle.
The world weightlifting
record for the "press" is still held by the Russian Vasily Alexeyev at
521.5 pounds. The world record for the "clean-and-jerk" is 573 pounds,
held by another Russian, Andrey Chemerkin. How many people do you know
who can even press a third of that weight? One cubic yard of soil weighs
nearly five times the world weightlifting records. Could you push back
500 pounds of soil with your arms or legs or, more importantly, could
you breathe or even survive under the weight?
Plain old dirt is
so heavy that when you get caught under it, you do not have the strength
to move or breathe as the dirt presses against your chest. Think about
it! That's why trenching work needs special protective systems—so workers
can go home safe and healthy at the end of the day.
Protective Systems
OSHA's excavation standard requires employers to provide sloping (or benching),
shoring, or shielding to protect employees in excavations 5 feet or more
in depth. The only exception is for a trench dug in stable rock, where
there is no loose soil or likelihood of a cave-in. Excavations less than
5 feet deep need not be protected unless a competent person has determined
there is a cave-in hazard.
At a minimum, companies
should remember the three s's— sloping, shoring, or shielding— when protecting
employees and follow the guidance given in the OSHA excavation standard's
8 appendices for sloping, shoring, and shielding.
"A fire department
rescue team helps a worker to safety after a trench cave-in."
OSHA excavation standard's
8
appendices for sloping, shoring, and shielding.
Despite OSHA's ongoing efforts in outreach, voluntary compliance, training,
and rigorous enforcement of the excavation standard, some contractors
still choose to ignore excavation safety. Contractors willing to take
risks to save time and money at the expense of protecting employees should
consider the potential consequences. The ultimate consequences are the
loss of lives or disabling injuries. Taking short cuts could also lead
to damaged equipment, property or structure damage, loss of insurance
or increased insurance premiums, law suits, public scrutiny from bad press,
or an OSHA inspection resulting in monetary penalty or other legal or
criminal consequences.
8
Title 29 of the Code of Federal Regulations (CFR) Part 1926.650-652.
For those contractors
who continue to take the "low road" in excavation safety, who believe
that "it's such a short job, shoring or sloping is not worth the trouble,"
word of advice—be aware of the public's heightened awareness of trenching
and excavation hazards before you violate the law. More and more referrals
for trenching inspections are from citizens, fire and rescue personnel,
local and state police, consulting engineers, building officials, and
others.
Contractors wishing
to take the "high road," who want to learn more about protecting employees
in excavations, and who believe that avoiding the risk of cave in is always
worth the trouble have many resources available to them, including OSHA's
webpage at http://www.osha.gov.
This Internet site includes topics such as safety standards, safety training
centers, available courses,materials and publications, and listings of
non-OSHA resources nationally and worldwide. The site also has a trenching
information page dealing with site evaluations, hazard recognition and
control, compliance, training, and more.
Another electronic resource is the OSHA Technical Manual (TED 1-0.15A)
Section V: Chapter 2, which summarizes the excavation standard and can
assist safety and health consultants, OSHA field staff, and others in
recognizing and preventing trenching and excavation hazards.
Employers also can
contact their designated OSHA state or territory consultation office for
guidance. Under Section 7(c)(1) of the Occupational Safety and Health
Act,9 this program provides free onsite consultation to
small employers. The program helps employers in evaluating their worksites
for existing and potential hazards and in complying with OSHA regulations.
Additionally, regional offices have designated compliance staff who are
proficient in various
disciplines such as trenching and excavation.
Partnerships
In addition to its strong enforcement, OSHA continues to stress the
importance of outreach and partnership as a way to improve worker safety
and health. One of OSHA's most recent initiatives is the Construction
Accident Emphasis Program (CARE) in Florida. OSHA staff are building cooperative
relationships with employers, educators, national and local trade groups,
unions, insurance groups, state consultation staff, and others to focus
on small employers within the state to help reduce the number of fatalities
in the construction industry.
9
Public Law 91-596, December 29, 1970. As amended by P.L. 101-552, 3101,
November 5, 1990; and PL 105-241, September 29, 1998.
CARE focuses on the
top four hazards in construction: falls, struck-by (e.g., equipment or
machinery), electrocution, and caught-in or between (e.g., equipment,
buildings, and materials). This cooperative effort seeks innovative ways
to prevent construction accidents through media, advocacy groups, religious
organizations, Internet, town hall meetings, and special outreach materials.
Similarly, OSHA's Philadelphia region is considering a special outreach
effort with business and unions to heighten the awareness of the dangers
of trenching work.
What's more, OSHA
has its own Training Institute in Des Plaines, IL, which offers a variety
of safety and health courses for federal and private sector employers
and employees. A schedule of classes is available under Outreach
on OSHA's website at www.osha.gov.
As statistics show,
employers and contractors must do more to protect their employees working
in excavations. OSHA is willing to help employers who need guidance, training,
or information on trenching issues.
For more information
on these and other available services, visit OSHA's website or contact
your nearest OSHA Area Office or the Directorate of Construction in OSHA's
National Office at (202) 693-2020.
Boom is an occupational
safety and health specialist in OSHA's Office of Construction Services,
Directorate of Construction, in Washington, DC.
"The workers shown here could suffer severe injuries or death
from a potential cave-in. The trench has no sloping, shoring, shielding,
or safe exit; the workers have no hard hats or personal protective equipment."
Reminders for Trenching
and Excavations
Competent Person
The designated competent
person must have the authority to take prompt corrective measures to eliminate
existing and predictable hazards and to stop work when required, and be
able to demonstrate the following:
- Training, experience,
and knowledge of:
- Soil analysis;
- Use of protective
systems; and
- Requirements
of Title 29 Code of Federal Regulations (CFR) Part 1926 Subpart
P.
- Ability to detect:
- Conditions
that could result in cave ins;
- Failures
in protective systems;
- Hazardous
atmospheres, understand utilities, and other hazards as noted below.
Surface Crossing of Trenches
Surface crossing of
trenches should be discouraged; however, if trenches must be crossed,
such crossings are permitted only under the following condition:
- Vehicle crossings
must be designed by and installed under the supervision of a registered
professional engineer.
Walkways or bridges
must be provided for foot traffic. These structures shall:
- Have a safety
factor of 4;
- Have a minimum
clear width of 20 inches (0.51 meters);
- Be fitted with
standard guard rails; and
- Extend a minimum
of 24 inches (.61 meters) past the surface edge of the trench.
Access and Egress
Access to and exit
from the trench require the following conditions:
- Trenches 4 feet
or more in depth must have a safe means of egress.
- Spacing between
ladders or other means of egress must be such that a worker will not
have to travel more than 25 feet laterally to the nearest means of egress.
- Ladders must
be secured and extend a minimum of 36 inches (0.9 meters) above the
landing.
- Metal ladders
must not be used when working around utilities where inadvertent contact
could cause electrical shock or electrocution.
Exposure to Vehicles
Procedures to protect
employees from being injured or killed by vehicle traffic include:
- Providing employees
with and requiring them to wear warning vests or other suitable garments
marked with or made of reflectorized or high-visibility materials.
- Requiring a designated,
trained flagperson as well as signs, signals, and barricades when necessary.
- Back up alarms
where necessary.
Exposure to Falling Loads
Employees must be
protected from loads or objects falling from lifting or digging equipment.
Some procedures designed to ensure their protection include:
- Employees may
not work under raised loads.
- Employees must
stand away from equipment that is being loaded or unloaded.
- Equipment operators
or truck drivers may only stay in their equipment during loading and
unloading if the equipment is properly equipped with a cab shield or
adequate canopy.
- Head protection.
Warning Systems for Mobile
Equipment
One or more of the
following steps must be taken to prevent vehicles from accidentally falling
into the trench:
- Install barricades
where necessary.
- Use hand or mechanical
signals as required.
- Install stop
logs if there is a danger of vehicles falling into the trench.
- Grade soil away
from the excavation; this will assist in vehicle control and channeling
of run-off water.
Hazardous Atmospheres
Employees shall not
be permitted to work in hazardous and/or toxic atmospheres. Such atmospheres
include those with:
- Less than 19.5
percent or more than 23.5 percent oxygen;
- A combustible
gas concentration greater than 20 percent of the lower flammable limit;
and
- Concentrations
of hazardous substances that exceed those specified in the Threshold
Limit Values for Airborne Contaminants established by the American Conference
of Governmental Industrial Hygienists.
All operations involving
such atmospheres must be conducted in accordance with OSHA requirements
for occupational health and environmental controls (see Subpart D of 29
CFR 1926) for personal protective equipment and for lifesaving equipment
(see Subpart E, 29 CFR 1926). Engineering controls (e.g., ventilation)
and respiratory protection may be required.
When testing for
atmospheric contaminants, the following should be considered:
- Testing should
be conducted before employees enter the trench and should be done regularly
to ensure that the trench remains safe.
- The frequency
of testing should be increased if equipment is operating in the trench.
- Testing frequency
also should be increased if welding, cutting, or burning is done in
the trench.
Employees required
to wear respiratory protection must be trained, fit-tested, and enrolled
in a respiratory protection program.
Emergency Rescue Equipment
Emergency rescue equipment
is required when a hazardous atmosphere exists or can reasonably be expected
to exist. Requirements are as follows:
- Respirators must
be of the type suitable for the exposure. Employees must be trained
in their use and a respirator program must be instituted.
- Lifelines must
be provided and attended at all times when employees enter bell-bottom
pier holes or other similar hazards.
Standing Water and Water
Accumulation
Methods for controlling
standing water and water accumulation must be provided and consist of
one or more of the following if employees are permitted to work in the
excavation:
- Use of special
support or shield systems designed for additional loading.
- Water removal
equipment, i.e. well pointing, used, and monitored by a competent person.
- Safety harnesses
and lifelines used in conformance with 29 CFR 1926.104.
- Surface water
diverted away from the trench.
- Employees removed
from the trench during rainstorms.
- Trenches carefully
inspected by a competent person after each rain and before employees
are permitted to re-enter the trench.
Inspections
Inspections must be
made by a competent person and should be documented. The following guide
specifies the frequency and conditions requiring inspections:
- Daily and before
the start of each shift;
- As dictated by
the work being done in the trench;
- After every rainstorm;
- After other events
that could increase hazards, e.g. snowstorm, windstorm, freeze/thaw,
earthquake;
- When fissures,
tension cracks, sloughing, undercutting, water seepage, bulging at the
bottom, or other similar conditions occur;
- When there is
a change in the size, location, or placement of the spoil pile; and
- When there is
any indication of change or movement in adjacent structures.
Source: US Department
of Labor, Occupational Safety and Health Administration, OSHA Technical
Manual, Section V, Chapter 2, Excavations: Hazard Recognition in Trenching
and Shoring, "X. Special Health and Safety Considerations" (Washington,
DC). See also Subject Index at www.osha.gov.
This paper appears in the eLCOSH website with the permission of the author
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