PSFA Trench Rescue
Relevant Reference Material
OSHA 29 CFR1926.650: Scope, Application and Definitions
OSHA 29 CFR1926.651: Specific Excavation Requirements
OSHA 29 CFR1926.652: Requirements for Protective Systems
OSHA 29 CFR 1926 Subpart B Appendices A-F
National Fire and Rescue; Trench Rescue Secrets, Parts 1 & 2.
Patrick Moore
FEMA Structural Collapse Technician Course, Student Manual,
Module 2B Shoring Construction,
http://www.fema.gov/emergency/usr/sctc.shtm
Introduction
Each year, 1,100
workers are severely
injured and 100 workers
die in trenching and
excavating accidents
Why do trench accidents
occur??

Complacency
 Shortcutting of safety for profit
 Weekend warriors-no shoring utilized
 Ignorance of hazards
 Unprepared or poorly trained in excavation
Anatomy of a Trench

Trench-Trenches are narrow excavations
made below the surface of the ground. In
general, the depth is greater than the width.
However, the width of a trench is not
greater than 15 feet. An excavation is also
considered to be a trench
 In reality, an open grave waiting for an
occupant
Inherent trench problems
Natural and man made forces began acting
immediately to close a trench once its been
created
These forces overcome the strength of the soil
composition and cause the trench to
eventually collapse
Dirt Dynamics

1 cubic foot of dirt weighs 100 lbs
 1 cubic yard of dirt weighs 2,700-3,500 lbs
 1 cubic foot of dirt will fill eight 1 gallon
buckets
 1 cubic yard of dirt will fill 203 1 gallon
buckets
3
1
1
1
3
3
3
Soil Types

Type A-Most stable:clay, silty clay and hardpan
(resists penetration) No soil is type A if it is
fissured, is subject to vibration of any type, has
previously been disturbed or has seeping water
 Type B-Medium stability:silt, sandy loam,
medium clay and unstable dry rock, previously
disturbed soils unless otherwise classified as Type
C. Soils that meet the requirements of Type A soil
but are fissured or subject to vibration
Soil Types continued:

Type C-Least stable:gravel, loamy sand,
soft clay, submerged soil or dense, heavy
unstable rock and soil from which water is
seeping freely
Soil Effects on Victim

Traumatic Asphyxiation
– Soil restricts expansion of victims chest
– Soil blocks airways
– Causes suffocation

Impact crushes the victim:
– Breaking limbs
– Causing internal injuries
– Causing soft tissue injuries
Victim Survival Profile

Time is the biggest factor
 8-10 min.’s for response
 6-10 min.’s for initial assessment
 18” of dirt = 2500-3500 pounds
 Hazard Risk Assessment Profile needs to be
considered
Types of Trench Accidents
Spoil pile slide
Occurs when improper
techniques are used and the
excavated material is not
placed far enough away
from the trench lip
UNSAFE
Slough In (cave in)
Slough trench lip
Most commonly occurs to
previously excavated
materials, primarily in sand,
gravel mixtures
Side wall shear
Occurs commonly to
clay type soils
exposed to drying
Side wall shear
Trench Terminology
Lip
Lip extends 2 feet
vertically and
horizontally from
the edge of the
trench. If the spoil
pile is located
within 2 feet of the
trench, it must be
removed.
Padding the Lip
Acceptable
materials: 2 x
12 lumber, 4 x
8 ¾” or 5/8”
plywood or
trench panels.
Should extend
from an area of
stability to
instability, if
end of trench
is accessible,
start there.
Padding the Lip
Trench Terms
Angle of Repose
The greatest angle
above the horizontal
plain at which loose
soil will lie without
sliding. Reducing
this angle will
reduce the amount
of spoil slide
Trench Terms
Uprights-Vertical supports that attach
panel to upright. Shoring is attached
to uprights between panels (usually 2
x 8’s or 12’s)
Panels-Support side walls of trench
Pre-made Shore form panels, 4 x 8
sheeting of 2 ¾” plywood
Shoring-Horizontal bracing
between panels, can be pneumatic
or timber shoring
Terms
Scabs-Hold timber shoring
firmly in place against
uprights. 2 x 4 pieces
Spoil pile-The material
excavated from the trench
Trench
Terms
Lowering linesLine used to lower
pneumatic shoring.
Lines should be of
a different color
Making the Trench Safe

Three ways to “safe” a trench:
– 1.-Slope the angle of repose
– 2.-Benching
– 3.-Shoring/Shielding
Sloping the angle of repose and benching require
backhoes as well as additional manpower.
Shoring operations require well trained
coordinated rescuers
Shoring Basics
Shoring Types:Shoring is the provision
of a support system for trench
faces used to prevent movement of
soil, underground utilities,
roadways and foundations.
Shoring Types
Hydraulic Shoring:
A prefabricated strut
and/or system
manufactured of
aluminum or steel.
Pressurized w/5 gal
hand pump to 5001000 psi. Pressure
must be maintained,
no locking device.
Shoring Types
Pneumatic Shoring System:
Works in a manner similar to
hydraulic shoring, primary
difference is that pneumatic
shoring uses air pressure to
set shores (can be set
manually)
Strut Extension
Pneumatic Strut
Swivel strut base
Shoring
Types
Timbering: Difficult and
time consuming task. 4 x
4 lumber generally used
for timbering.
Shoring Objective
Transfer the force across the trench through the
upright and then into the opposite trench wall.
Transferring the potential energy will complete the
protective system giving rescuers a safe area in
which to work
Shielding
Trench boxes are different from shoring
because instead of shoring up the trench
face, they are intended to primarily protect
workers from slough ins.
IV.
Shoring Operations
Shores should be located 18”-24” from the
floor and the lip of the trench
 Shores should be no more than 48” apart
vertically
 Placement of the first shore should be from
the outside of the trench using
hydraulic/pneumatic shoring (shores should
not be placed directly above the pt/victim)

Pneumatic Shoring Order

First shore should be placed in the middle
of the upright
 Second shore is placed in the top of the
upright
 Third shore is paced in the bottom of the
upright
– shores are lowered by lowering lines directed
by the shoring officer then “shot”
Shooting Shores

After shore is lowered and is in place
(level), the following commands are to be
given by shoring officer:
– “Prepare to Shoot”
– “Shoot”
– Pneumatic shores are shot at 100 psi and
released at 150 psi
Corner Shoring
Corner Shoring
Corner Shoring
Force Block
6x6
Corner Shoring
Nailing Shores
Nail half way into 45 swivel
base and then bend nail
over corner of base
Off Setting Shores
Wales
Horizontal members,
installed on either the
inside or outside of
panels, to span openings
along the trench walls or
create a space by
spanning panels.
Inside Wale
Wales
Outside Wale: To span
a slough in of a trench
wall. Note the Low
pressure bag
Timbering

The first shore is placed at the top of the
upright and requires the rescuer to enter the
trench on a ladder
 The second shore or middle shore is placed
in the middle of the upright, again forcing
rescuer further in the trench on a ladder
 Last shore is placed on the bottom of the
trench above trench floor
Railing the Uprights
2” x 4” are nailed onto the
uprights
Scab blocks then inserted to hold
timer above/below
Faster and easier than traditional
scab block method
Alternate Railing Method
2” x 4”’s placed horizontally
above and below timbers
Railing nailed on in the same
fashion, allow for timer to slide
vertically (scab block width)
Hazard Control

Hazards may include:
– Electrical utilities
– Ruptured gas lines
– Broken water/sewer
–
–
–
–
lines
Workers on scene
Spoil pile
Falling debris in trench
O2 deficient
atmosphere

Vibration from:
– Operating machinery
on scene
– Nearby traffic
– Responding apparatus
Rescue Operations
DO NOT GO INTO THE HOLE!!!!
First and foremost, the company officer needs to limit the
possibility of further injuries and death, get the hole under
control, make it safe for everyone, and, with the proper
equipment, start to develop a safe work space.
Safety First

Appropriate PPE:
– Dress for success, right gear should include
head, hand, foot, eye, ear and respiratory
protection as appropriate.

Make the general area safe:
– Establish a hot, warm and cold zone
Safe the General Area

First arriving apparatus:
– Stops and is turned off no less than 250’ from
the dispatched location. This becomes the
warm zone
– Establish command and designate a staging
area for other other responders with
equipment/apparatus.
– Assign a staging officer
Cold/Hot Zone
Cold Zone Staging should exceed 500’or
more from trench incident site
 Hot Zone Area:

– Should extend 100’ in all directions around the
site
– Use fire line tape, rope, etc. to mark these zones
Rehab
Operations
PIO
Trench
Staging
100 Feet
Personnel
Staging
IC
250 Feet
500 Feet
Outer Circle Check

Restrict entry to site
 Eliminate sources of vibration, stop and
shut down construction equipment
 Identify witnesses to the accident if any
 Identify job foreman
 Begin to establish incident perimeters
Inner Circle Check

Approach site from end of trench
 Identify victim location (if possible) using
witnesses, location of trench failure,
surveyors markers etc.
 Identify number of patients
 Establish patient/victim condition if
possible
Making the Rescue Scene
Safe
Means monitoring the environment around the incident site.
There is a good chance a hazardous environment exists and
perhaps oxygen deficient space. Remember established confined
space limits and use them to define problems. (Limited air??
Limited access?? Is the space continuously monitored?)
Inner Circle Check
How is the patient trapped?
-totally buried, if so, where??
-trapped by utilities
Where???
– Don’t forget to consider Hazard Risk
Assessment Profile
– Direct non trapped workers out of trench

Establish full command structure
Operations: 4 Team Approach

1.-Excavation
 2.-Monitoring
 3.-Shoring
 4.-Rescue
Excavation

Coordinates operation for dewatering (if
needed
 Initiates/completes lip safety
 Removes spoil pile, reduce angle of repose
Dirt/Debris Removal
5 Gallon
buckets
lowered/raised
from trench or:
Call McCutcheon Enterprises for a Vacuum
Truck 724-568-3623
Monitoring

Monitors trench during entire rescue
operation
 Establishes ventilation in all levels of trench
 Establishes back-up ventilation in case of
primary ventilation failure
Shoring

Shores trench with pneumatic, hydraulic,
timber shoring
 Establishes cutting table if needed
 Establishes air supply for pneumatics with
back up supply
 Under control of a shoring officer
Cutting Table at the cut station
Rescue

Prepares and executes disentanglement
procedures
 Patient/victim packaging
 Patient/victim removal
 Rope system if needed (4:1, 5:1)
 A-Frame/gin pole if needed
Rescue

Disentanglement procedures:
-Remove dirt/soil away from victim,
accomplished by hand digging and buckets
-Clear the head and chest if victim caught in
collapse in this position
-Secure patient using acceptable devices
(LBB, LSP, Reeves, Stokes, Harnesses)
Rescue

Be prepared for vertical extrication:
– Consider A-Frame (engine co. task)
construction away from hot zone and radio for
it when ready
– Mechanical advantage system needed
– Shoring position may be impede vertical
pt/victim removal
A-Frame Use
A-Frame
Summary
Managing the incident is the key to maintaining control, because
you run a very good chance of working eight hours or more in
many cases. Incident complexity and risk demand strong
command, control and decision making ability.
Hazards in a trench rescue can be deadly and strike without little
or no warning.
DON’T GET INJURED