FACE 85-05: Confined Space Incident Kills Two Workers- Company Employee and Rescuing Fireman
INTRODUCTION
On November 15, 1984, one worker died after entering a toluene
storage tank. During the rescue attempt, a fireman was killed
when the tank exploded.
SYNOPSIS OF EVENTS
The owner of a bulk petroleum storage facility discovered that
the toluene storage tank (10 feet in diameter and 20 feet in
height) was contaminated and would have to be drained and
cleaned. Since the tank's only access portal was located on top
of the upright cylindrical tank, the owner decided to have a
clean-out access portal installed at the bottom of the tank when
emptied. A contractor was called to provide cost estimates for
installing the portal. The contractor performed a site survey of
the tank and told the owner that the tank must be drained, all
sludge removed, and thoroughly ventilated before he would install
the portal. The owner directed his maintenance supervisor to get
the tank prepared for the contractor.
On the day of the incident the supervisor and an unskilled
laborer (a San Salvadorean immigrant on his first day back on the
job after working another job for approximately 2 months) drained
the tank to its lowest level - leaving 2 to 3 inches of sludge
and toluene in the bottom - and prepared for a "dry
run" of entry into the tank via the top access portal.
The supervisor rented a self-contained breathing apparatus (SCBA)
from a local rental store and instructed the laborer in use of
the SCBA and in the procedure they intended to follow. Since a
ladder would not fit into the 16-inch diameter access hole, the
supervisor secured a knotted, 1/4-inch rope to the vent pipe on
top of the tank and lowered the rope into the hole. The 16-inch
diameter opening on the top of the tank was not large enough to
permit the laborer to enter wearing the SCBA. Therefore, it was
decided the SCBA would be loosely strapped to the laborer so it
could be held over his head until he cleared the opening. Once
entry had been made, the supervisor was to lower the SCBA onto
the laborer's back so it could be properly secured.
Immediately prior to the incident, both employees were on top of
the tank. The laborer was sitting at the edge of the opening. The
supervisor turned to pick up the SCBA. While he was picking up
the unit, he heard the laborer in the tank. He turned and looked
into the opening and saw the laborer standing at the bottom of
the tank. He told the laborer to come out of the tank, but there
was no response. The supervisor bumped the rope against the
laborer's chest attempting to get his attention. The laborer was
mumbling, but was still not responding to his supervisor's
commands. At this point, the supervisor pulled the rope out of
the tank, tied the SCBA to it and lowered the unit into the tank.
Again, he yelled to the laborer in the tank, bumped him with the
unit and told him to put the mask on. There was still no
response. The laborer fell to his knees, then fell onto his back,
and continued to mumble. At this point, the supervisor told the
facility manager (who was on the ground) to call the fire
department.
The first call went to the police department who relayed it to
the fire department. Included in the fire department response was
the hazardous materials team, due to the information received
about the material in the tank. The fire department (including
the rescue and the hazardous materials teams) arrived on the
scene approximately 10 minutes after the initial notification.
After apprising the situation, fire officials decided to
implement a rescue procedure rather than a hazardous materials
procedure. Therefore, removal of the disabled person inside the
tank was given top priority.
The 16-inch diameter opening at the top of the tank was not large
enough to lower a firemen donned in full rescue gear. Therefore,
it was decided to cut through the side of the tank to remove the
victim. The firemen were aware of the contents of the tank
(toluene) and the possibility of an explosion.
The procedure developed by the fire department involved making
two 19-inch vertical cuts and a 19-inch horizontal cut with a
gasoline-powered disc saw. After the cuts were completed, the
steel flap would be pulled down and the victim removed.
While the hazardous materials team was cutting, other firemen
were spraying water on the saw from the exterior to quench
sparks. Two other firemen were spraying water on the interior cut
from the top opening. Three firemen with the hazardous materials
team were doing the actual cutting; they were alternately
operating the saw because of the effort required to cut through
the 1/4-inch thick steel. Sometime during the horizontal cut a
decision was made to bring the two firemen off of the top, which
meant no water spray on the interior. Simultaneously, the
exterior water spray was removed to put out flammable liquid
burning on the ground as a result of the shower of sparks from
the saw. Thus, at the precise time of the explosion, no water was
being sprayed on the saw/cut from exterior or interior. Both
vertical cuts were completed and the horizontal cut was 95
percent complete when the explosion occurred.
One fireman was killed instantly from the explosion and several
were injured. The man inside the tank was presumed to be already
dead at the time of the explosion.
CONCLUSIONS/RECOMMENDATIONS
The conclusions and recommendations are presented in two parts:
Part I - the confined space entry; and Part II - the rescue
effort.
Part I - Confined Space Entry:
The following factors may have contributed to the confined space
fatality:
RECOMMENDATIONS
Written confined space entry procedures should be developed and
used. Procedures should contain the following: permit system,
testing and monitoring of the atmosphere, training of employees,
safety equipment/clothing, safe work practices, rescue
procedures, standby person requirements, and use of respiratory
protection.
Selection of proper respiratory protection -- whether it be a
self-contained breathing apparatus (SCBA) or supplied air system
-- is essential. Selection should be determined by the physical
limitations, equipment available, and work procedures.
Confined space testing and evaluation by a qualified person
before entry and implementation of safety measures will help
reduce risk-taking by employees.
Vertical access from the top of a 20-foot tank by a rope was
found to be physically impossible while wearing respiratory
protection and protective clothing. An additional access port on
the side near ground level would eliminate this problem. The port
should be of adequate size to permit entry of a worker wearing
full protective clothing.
Workers must be properly trained (in English, Spanish, or the
prevailing language) in confined space entry procedures and use
of personal protective equipment. Also, the tank contents and
known potential hazards should be discussed.
A prior accident should have alerted someone that additional
protection was needed. If entry procedures are being followed and
an accident occurs, it is necessary to re-evaluate the procedures
and make necessary corrections for employee safety.
Part II - The Rescue Effort:
The following factors may have contributed to the rescue effort
fatality and injuries:
RECOMMENDATIONS
While cutting the tank and assisting fellow firemen who were
cutting, one fire fighter stood directly in front of the opening,
rather than to the side. This maximized the impact the victim
received from the explosion. It is recommended that procedures be
outlined that minimize such risk by firemen.
When hazardous tasks are performed only essential personnel
should be in the immediate area, regardless of perceived risk by
fire fighters. Nonessential personnel should be permitted only
after the hazardous task(s) has been completed.
More extensive departmental procedures for efforts involving
responses to explosive environments and hazardous materials are
needed. Procedures should include command responsibilities,
determinations of and distinctions between rescue and recovery
efforts, uses of potential sources of ignition, methods to
minimize risks of ignition, etc.
City fire departments should establish a registry of confined
spaces and toxic/explosive substances for specific companies
within the area in which they serve. Such a registry should
provide not only the name of the substance, but should also
provide sufficient information so that emergency response
personnel will have one comprehensive source that provides
information sufficient to safely effect a rescue effort.
Research is needed to determine the best methods (if any) to gain
entry in such circumstances. Cutting may be too hazardous, even
with the use of water sprays.
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This page was last updated on 11/21/05