Transcript TRENCH OPERATIONS - Fire Training Tracker

TRENCH OPERATIONS
For safety is not a gadget but a state
of mind. ~Eleanor Everet
Objectives
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Governing Standards
Anatomy of a Trench
Soil Physics
First arriving units
actions/ Scene
management
Equipment Familiarization
Type of Trench Collapses
Assignments &
Responsibilities
Techniques for Protection
OSHA CFR 1926 Subpart P,
Excavation:
– Important to rescuers for several reasons
 First the data and information will give you the
information from which you can decide the
protective systems.
 Secondly, knowledge of the standard, its
requirements, protective systems, and soil
classifications will qualify the user as a “Competent
Person”.
General requirements
All trenches must be protected before entries except:
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 Those made entirely of stable rock.
 Those less than five feet in depth, including the height of the spoil pile must
be protected.
Protection:
– Anything more than five feet in depth, including the height of the spoil pile must
be protected.
Spoil Pile:
– Must have two-foot set back for the lip.
Egress:
– Trenches four feet or greater in depth must have a means of egress every
twenty-five feet “Ladders”.
Atmospheric:
– Trenches four feet or greater in depth must be tested before entry.
Definitions
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A “trench”, means a narrow excavation (in relation to its length) made
below the surface of the ground. In general, the depth is greater than the
width, but the width measured at the bottom is not greater than 15 feet.
WIDTH
DEPTH
”Excavation”, includes a trench
It means any man made cut, cavity, trench, or depression in an earth
surface formed by the earths removal. Again, in practical terms, when a
hole is more than 15 feet wide at its base, it is called specifically an
excavation. Overall, an excavation is wider than it is deep.
Competent Person
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One who can identify existing or
predictable hazards in the surrounding
that are unsanitary, hazardous, or
dangerous to employees. Also has
authorization by the nature of their
position to prompt corrective measures to
eliminate them. The person shall be
knowledgeable in the requirement of this
part.
Anatomy
How Heavy is Dirt?
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Physical forces
associated with
collapse:
– Dirt has volume that
has mass and weight
– One cubic foot of dirt
weights between 85
and 125 pounds per
cubic foot.
Weight of a Volkswagen
2,785 Pounds
Weight of one cubic
yard of soil
2,700 Pounds
Soil Physics
Compounding the
effects of gravity is
hydrostatic pressure
 Add the weight of
water and rock, a
cubic foot of dirt can
be as much as 125
pounds per cu/ft
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A six foot trench:
– at the four foot level has
approximately 400 pounds
vertical weight.
– Lateral forces could be
expected to be 132
pounds of horizontal
pressure
– Distribution of lateral
pressure occurs on about a
45 degree angle from the
bottom
Accidents without cave-ins
– Most emergencies in
trenches deal with
something other than a
collapse
– Most of the work is done
after the trench has been
dug
– In these cases don’t be
lulled to sleep by a
protected trench
– Approach identically as an
open trench
Hazards Present?
First Arrival
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Apparatus spotting
– Spot at least 100 ft from location
Create Exclusion Zones (on next slide)
Size-up – accurate address of location, call for help
Secure RP, job foreman, or witness to accident
Safety 360 Review – approach trench from the end, Secondary sizeup
Rescue or Recovery mode
Assess potential hazards to rescuers (Atmospheric, water,Trench
etc)
Make The Trench Lip Safe – ground pads/ Ladder bridges
Shielding of patient – with material on site, plywood, backboard
Air monitoring – Bottom at patient, middle and top of trench
Apparatus Base Area with manager. location?
Trench Scene Management
Exclusion Zones
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Hot Zone 0 – 100 ft.
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Warm Zone 100 –
150 ft
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Cold Zone 150 – 300
ft.
Ground pads
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For distribution of weight on trench edge
Ladder Bridge
Review of Monitoring Values
Atmospheric
Level
Combustible /
Flammable gas
10% of LEL
Oxygen
Toxicity
Action
If outside the
space correct
atmosphere. If
inside the space
begin exit
Less than 19.5%
If outside the
or greater than
space determine
23.5%
problem and
correct. If inside
the space begin
to exit
CO – 35 ppm
If outside the
H2S –10 ppm
space determine
cause of problem
and correct, If
inside the space
begin to exit.
Monitor
Alarms both
visually and
audibly
Alarms both
visually and
audibly
Alarms both
visually and
audibly
Equipment Familiarization
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Strongbacks/Uprights
= Shoring Panels
Timber
Waler
Palm nailer
Airshore
Speedshore
Types of Collapses
Spoil pile slide
 Excavated earth too
close to the lip
 Heavy rain increasing
wt of pile
Slough In / Lip slide
Slough failure
 The loss of part of the
trench wall
Sheer Wall
Shear wall collapse
 section of soil that loses
it’s ability to stand
Toe Failure
Toe failure
 Slough that occurs at
the bottom
 Found in location of fill
dirt
Bell Pier Condition
Bell pier condition
 Long term toe failure
on both sides
Wedge Failure
Wedge failure
 Occurs with intersecting
trenches, T or L Trench
 Angled section of earth
falling from the corner
of an intersecting
trench
Assignments and Responsibilities
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Extrication/ Entry Team
– Developing plan for patient extrication
– Also personnel used for digging
– Assists Shoring Team to set shores
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Shoring Team
– Assembling, placing and removing shoring & walers
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Panel Team
– Place ground pads
– Prepare and placement of panels
TECHNIQUES FOR TRENCH
PROTECTION
Ops operating within trench
 Straight wall trench procedures:
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– Set middle set of panels as directly over the
victim as possible
– For Pneumatic Struts:
 Set middle shore
 Set top shore
 Set bottom shore
TECHNIQUES FOR TRENCH PROTECTION
Outside Waler
– Uses outside walers to
span opening
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Outside waler
procedures:
– Place pickets to tie walers
– Place and tie off bottom of
Waler
– Place and tie off top of
Waler
– Set middle set of panels as
directly over victim as
possible
Inside Waler
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Inside walers are
used to span a set of
panels for the
purpose of creating
an open space
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The intersecting “T”
trench is a very
unstable trench
because not only is
one wall exposed, but
a section has been
cut that intersects the
other wall.
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The “L” trench can be
describe as two
trenches that
intersect at there
ends
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Deep trenches are
those trenches over
10 feet but not more
than 20 feet
Pier-hole
Trench Environments
Take Home Points
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Create a Hot, warm and cold zone
– Hot zone 0 – 100 ft
– Warm zone 100 – 150 ft
– Cold zone 150 – 300 ft
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Call for help, location, Staging
Control Traffic movement
Shut down all heavy equipment
operating within 300 ft of the
collapse
Ladders for egress every 25 feet.
Ground pads
Air monitoring
Spoil pile moved 2 feet from lip of
trench
Questions?
Thank you
For safety is not a gadget but a
state of mind. ~Eleanor Everet
Rotational Failure
Rotational failure
 Scoop shaped collapse
that starts at the lip
and transmits itself to
the trench walls