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O
How to
carry
out
a
trench
T
W
O
H
TRENCH RESCUE – THE BASICS
“Enough is enough” is most likely the reason why in
the US it is forbidden to enter an unsecured trench or
ditch, and there are strict regulations as a result of
the deaths of many firefighters who perished while
trying to save others. Although there are no current
regulations in Europe, the same issues should be
considered: Peter Schellekens from ResQtec takes a
look at some of the basics.
I
t is human instinct, especially for emergency personnel, to
try and save a person in need. Can you imagine having to
see somebody trapped, covered in soil, and maybe only
1.5 meters out of reach? What would you do? Jump in and
try to help him of course. This human instinct has taken the
lives of many would-be responders. The chances of secondary
collapse are almost certain – so what are the right procedures
during a trench rescue operation?
What is the deal with trench rescue?
Peter Schellekens,
ResQtec.
ResQtec launched
the new ProFix Max
shore at the
Interschutz in
Leipzig.
It has a locking
mechanism that
locks automatically
anywhere on the
cylinder stroke –
just extend and
lock. It is thus ideal
for trench but also
for structural or
stabilisation
purposes. ProFix
Max is part of the
interchangeable
Octopus system eg
where a standard
ram can be
connected to a
shore or an
extension can be
used with the ram.
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A trench is basically a hole in the ground, and generally most
incidents take place on construction sites, such as piling
holes. Due to ground stability and the type of soil and several
other factors trenches can logically collapse. If there is
somebody in the trench the victim might become entrapped
or worse: he becomes buried under the rubble. Prolonged
entrapment causes crush syndrome, an affliction whereby
limbs are cut off from oxygen, and the toxins produced by
the crushing of the muscles start to build up. It is general
practice to not suddenly release a victim that has been
trapped for longer than 15 minutes (this could occur even
sooner depending on factors such as depth and
temperature), as the shock caused by the release of the
toxins can instantly kill. Then additional difficulties are the
presence of water in the trench. The problem with rescue
operations is that a second collapse is very likely. Common
sense dictates that once the soil has collapsed it can happen
again, especially during the motions of a rescue operation.
The objective
The objective is to create a safe working area (safe box) to
get to the patient and treat him. The chance of a secondary
collapse can be eliminated by using shores to stabilise the
side of the collapsed trench. These can be made of wood
but in general, mechanical shores are used seeing as they
are easier and quicker to set up.
The procedure
In the following paragraph several aspects of trench rescue
are highlighted. In no way are they complete and nor should
they be used as guidance or considered as training.
R FIRE & RESCUE R THIRD QUARTER 2010
To carry out a trench rescue operation formal and certified
training should be always attended.
TRENCH RESCUE CAN BE DIVIDED INTO
DIFFERENT PHASES
Phase I: size –up
Issues like victim location, condition and number of victims.
Immediate hazards, for example unstable ground or
atmospheric hazards such as gases should be identified in
advance. It is essential to determine the situation is a rescue
or a recovery. It may very well be that the patient is already
dead. Safety of the rescuer is at the heart of every trench
rescue operation.
Phase II: pre- entry operations
Creating a safe working area is essential: establish working
zones and create a safe distance between traffic whilst
implementing measures of crowd control. Securing hazards
like electricity, gas, and ventilation of the trench can
commence. If there is water in the trench, try to drain it.
Phase III: rescue operation
Before starting work inside the trench, first sides of the trench
should secured. The sides are the area most likely to
collapse. They should be approached from the end. Ground
pads (wooden plates) are placed to distribute weight of the
soil over a larger area.
Logically, excess soil is placed on one side of the trench. It
should be assessed what is possible as usually space is
limited. Wooden boards are also placed here to distribute the
weight.
Then the work can commence on making the trench safe.
Place ladders generally no more than 15 meters apart so as
to allow a quick exit. When working with pneumatic shores,
panels (large panels and 2x10 boards) are placed between
the trench wall and the shore.
The shore is lowered into place, levelled, and then
pressurised to support the wall of the trench. Depending on
the height of the trench two or three shores are used. The
shore should not be much higher than 70 cm from the
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rescue operation
bottom and between shores not more than 125 cm from
first. The second or the third set of panels should not be
more then 1.2 meters away from the middle of the first
panel.
There is high possibility that the wall is uneven. Gaps can
be filled using soil once the panels are in place, or airbags
can be used with a large surface area pressing against the
panels. Low pressure bags or the NT lifting bags can serve
that purpose.
Before the trench can be entered, the shores need to be
mechanically locked and nailed to the wood, to eliminate the
chance of movement.
Trench rescue equipment
There are many different ways for your department to
approach a trench, the question is; what works for your
department? Trench rescue generally isn’t that common, but
when it does occur it’s about quick and safe response.
The most important aspect of trench rescue is the shoring.
Although wood shores work well, they require someone with
experience and superior training, and they will always take
more time than using a mechanical shore.
The best way to differentiate shores is in their locking
devices. Shores need to be mechanically locked before the
trench is secure. This is where the difference can be made in
safety and time saving. Some shores have an automatic
locking device, others work with threads or pins in
combination with rotating collars.
Automatic locking mechanisms work best in trenches, so
that going into the trench and manually locking a shore in
place isn’t necessary. But then the question arises about
buying of dedicated equipment: do you require shores just
for use in trench? The automatic locking mechanisms
currently in the market (except ResQtec’s ProFix Max, see
photo and caption opposite) below) perform well in
trenches, but not as well in other disciplines including
stabilisation or lift support in RTCs. Many departments choose
to go for a shore that can be used for several aspects of
technical rescue.
Conclusion
It is wise to prepare for trench rescue operations as incidents
will occur – not only in the US! Proper training is essential,
much of which is situational awareness and knowing what to
expect. Procedures and guidelines will prevent accidents.
It is advised to have the kit ready to be deployed, as this
will save tremendous amounts of time. It is also wise to
know where you can get more shores or wood if necessary. If
you are a department that wants to be prepared but don’t
expect a lot of incidents, go for a multipurpose shore.
As seen on front
fro
fr
fro
on
ntt cover
cov
ove
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er
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THIRD QUARTER 2010 R FIRE & RESCUE R
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