Transcript Trench Awareness Office of the State Fire Marshall of Illinois presented by the…

Trench Awareness
presented by the…
Office of the State Fire Marshall of
Illinois
Course Content
Introduction
 Trench Rescue Hazards
 OSHA Regulations
 Protective Systems
 Shoring System Design
 Rescue Shoring
 Trench Rescue Operations

Course Content
Introduction
 Trench Rescue Hazards
 OSHA Regulations
 Protective Systems
 Shoring System Design
 Rescue Shoring
 Trench Rescue Operations

Introduction
OSFM technical rescue certifications
 Definition of a trench
 Trenching operations
 Trench accidents and statistics

Introduction
OSFM technical rescue certifications
 Definition of a trench
 Trenching operations
 Trench accidents and statistics

OSFM Technical Rescue Specialist
Certifications
Confined-Space/Trench Rescue Awareness
Vertical Rescue I
(Equivalency available)
Vertical Rescue II
Confined Space Rescue
(Equivalency available)
Trench Rescue I
(Equivalency available)
Trench Rescue II
Introduction
OSFM technical rescue certifications
 Definition of a trench
 Trenching operations
 Trench accidents and statistics

Introduction
OSFM technical rescue certifications
 Definition of a trench
 Trenching operations
 Trench accidents and statistics

Definition of a trench
OSHA defines a trench as an excavation which is deeper
and longer than it is wide and is less than 15 feet wide at
the bottom.
Introduction
OSFM technical rescue certifications
 Definition of a trench
 Trenching operations
 Trench accidents and statistics

Introduction
OSFM technical rescue certifications
 Definition of a trench
 Trenching operations
 Trench accidents and statistics

Trenching operations
 OSHA protection
requirements are often ignored
 Contractors are often family businesses
Trenching operations
 OSHA protection
requirements are often ignored
 Contractors are often family businesses
Trenching operations
 OSHA protection


requirements are often ignored
Ignorance/complacency of risks
Economic factors
 Contractors
are often family businesses
Trenching operations
 OSHA protection

requirements are often ignored
Ignorance/complacency of risks
• Inexperienced contractor
• Experienced contractor with no history of problems
• Complaints of inconvenience from workers

Economic factors
 Contractors
are often family businesses
Trenching operations
 OSHA protection

requirements are often ignored
Ignorance/complacency of risks
• Inexperienced contractor
• Experienced contractor with no history of problems
• Complaints of inconvenience from workers

Economic factors
 Contractors
are often family businesses
Trenching operations
 OSHA protection

requirements are often ignored
Ignorance/complacency of risks
• Inexperienced contractor
• Experienced contractor with no history of problems
• Complaints of inconvenience from workers

Economic factors
• Cost of equipment
• Labor cost to install equipment
• Elimination of protection equipment to be awarded low bid
 Contractors
are often family businesses
Trenching operations
 OSHA protection

requirements are often ignored
Ignorance/complacency of risks
• Inexperienced contractor
• Experienced contractor with no history of problems
• Complaints of inconvenience from workers

Economic factors
• Cost of equipment
• Labor cost to install equipment
• Elimination of protection equipment to be awarded low bid
 Contractors
are often family businesses
Trenching operations
 OSHA protection

requirements are often ignored
Ignorance/complacency of risks
• Inexperienced contractor
• Experienced contractor with no history of problems
• Complaints of inconvenience from workers

Economic factors
• Cost of equipment
• Labor cost to install equipment
• Elimination of protection equipment to be awarded low bid
 Contractors

are often family businesses
Results in extremely emotional rescue scenes
Introduction
OSFM technical rescue certifications
 Definition of a trench
 Trenching operations
 Trench accidents and statistics

Introduction
OSFM technical rescue certifications
 Definition of a trench
 Trenching operations
 Trench accidents and statistics

Trench accidents and statistics
 Trenching
operations take place on a daily basis
in almost all jurisdictions
 Over 100 workers are killed annually in trench
accidents
 As much as 65% of those killed in trench
collapses are rescuers
Introduction
OSFM technical rescue certifications
 Definition of a trench
 Trenching operations
 Trench accidents and statistics

Course Content
Introduction
 Trench Rescue Hazards
 OSHA Regulations
 Protective Systems
 Shoring System Design
 Rescue Shoring
 Trench Rescue Operations

Course Content
Introduction
 Trench Rescue Hazards
 OSHA Regulations
 Protective Systems
 Shoring System Design
 Rescue Shoring
 Trench Rescue Operations

Trench Rescue Hazards

Hazards are not obvious
 Trenches
don’t appear dangerous
 Understanding the hazards requires training
 By-standers, co-workers, and even fire officers will not
understand the inaction of trained rescuers until the
trench is properly protected
Trench Rescue Hazards


Hazards are not obvious
Secondary collapse
 Depends
upon the type of collapse
 Responsible for most deaths in trench collapses
 Usually occurs just in time to trap a would-be rescuer
Types of collapses
Slough-in
Sidewall-in
Shear-in
Spoil-in
How rescuers become victims
Trench Rescue Hazards



Hazards are not obvious
Secondary collapse
The weight of dirt
 90-145
lbs. per cubic foot
 Averages 100 lbs. per cubic foot
 Average collapse is 1.5 cubic yards (about 4000 lbs.)
 A victim under 2 feet of soil will be under about 3000
lbs. of soil, approximately 1000 lbs. of which will be on
his chest
Trench Rescue Hazards




Hazards are not obvious
Secondary collapse
The weight of dirt
The speed that dirt can move
 Trenches
will often collapse within 1/10th of a second
 There is often little or no warning of collapse
 Spalling of soil or widening fissures are signs of
eminent collapse
 Escape is unlikely during a collapse
 Victims are often “frozen” in place
Trench Rescue Hazards





Hazards are not obvious
Secondary collapse
The weight of dirt
The speed that dirt can move
Rescues are usually long-term operations
 Trench
rescues will often require in excess of 4-6 hours
 The trench will become more unstable with time
Trench Rescue Hazards






Hazards are not obvious
Secondary collapse
The weight of dirt
The speed that dirt can move
Rescues are usually long-term operations
Backhoes are not safe for victim rescue
 The
operator is likely to inflict serious or fatal injury to
the victim
 The weight and vibration from the backhoe is likely to
accelerate the occurrence of a fatal secondary collapse
 Backhoes are an acceptable device for recovery
operations
Trench Rescue Hazards







Hazards are not obvious
Secondary collapse
The weight of dirt
The speed that dirt can move
Rescues are usually long-term operations
Backhoes are not safe for victim rescue
Trenches exceed OSHA limits
 OSHA provides
guidelines for trenches up to 15 feet
wide and 20 feet deep. Custom engineering is required
beyond those limits
 A contractor who did not provide proper protection for
his employees is likely to not understand the limits
Trench Rescue Hazards








Hazards are not obvious
Secondary collapse
The weight of dirt
The speed that dirt can move
Rescues are usually long-term operations
Backhoes are not safe for victim rescue
Trenches exceed OSHA limits
Buried utilities
 Many
more injuries and deaths in trenches are caused
by contact with buried utilities than are from collapse
 Rescuers are not immune to this danger
Trench Rescue Hazards









Hazards are not obvious
Secondary collapse
The weight of dirt
The speed that dirt can move
Rescues are usually long-term operations
Backhoes are not safe for victim rescue
Trenches exceed OSHA limits
Buried utilities
Impact or entrapment from falling objects
 This
is the leading cause of death and injury in trenches
 Rescuers must control this hazard prior to entry
Trench Rescue Hazards










Hazards are not obvious
Secondary collapse
The weight of dirt
The speed that dirt can move
Rescues are usually long-term operations
Backhoes are not safe for victim rescue
Trenches exceed OSHA limits
Buried utilities
Impact or entrapment from falling objects
Uncollapsed unprotected trenches still dangerous
 Rescuers
must be wary of apparently simple rescues
from uncollapsed trenches
Trench Rescue Hazards











Hazards are not obvious
Secondary collapse
The weight of dirt
The speed that dirt can move
Rescues are usually long-term operations
Backhoes are not safe for victim rescue
Trenches exceed OSHA limits
Buried utilities
Impact or entrapment from falling objects
Uncollapsed unprotected trenches still dangerous
Inadequate equipment for shoring
 Untrained
rescuers may be lulled into false security by
using inadequate shoring materials such as backboards
 Shoring systems require extremely strong materials
Trench Rescue Hazards












Hazards are not obvious
Secondary collapse
The weight of dirt
The speed that dirt can move
Rescues are usually long-term operations
Backhoes are not safe for victim rescue
Trenches exceed OSHA limits
Buried utilities
Impact or entrapment from falling objects
Uncollapsed unprotected trenches still dangerous
Inadequate equipment for shoring
Possible legal liabilities for fire officers
 Fire
officers may face both criminal and civil charges
for injuries to their personnel resulting from ignoring
OSHA regulations
Trench Rescue Hazards












Hazards are not obvious
Secondary collapse
The weight of dirt
The speed that dirt can move
Rescues are usually long-term operations
Backhoes are not safe for victim rescue
Trenches exceed OSHA limits
Buried utilities
Impact or entrapment from falling equipment
Uncollapsed unprotected trenches still dangerous
Inadequate equipment for shoring
Possible legal liabilities for fire officers
Course Content
Introduction
 Trench Rescue Hazards
 OSHA Regulations
 Protective Systems
 Shoring System Design
 Rescue Shoring
 Trench Rescue Operations

Course Content
Introduction
 Trench Rescue Hazards
 OSHA Regulations
 Protective Systems
 Shoring System Design
 Rescue Shoring
 Trench Rescue Operations

OSHA Regulations

Applicable regulations
 29
CFR 1926 Subpart P (Excavations)
 Applies to public sector and to Federal employees
 Illinois has adopted 1926 by reference in the Illinois
Register Part 350 Section 350.280
 Applies to municipal, fire district, and State
employees
OSHA Regulations


Applicable regulations
Methods of providing worker protection
 Sloping
 Shoring
 Shielding
Methods of providing worker protection
Sloping
Shoring
Shielding
OSHA Regulations



Applicable regulations
Methods of providing worker protection
Soil classifications
 Stable
rock
 Class-A
 Cohesive soils
 Clumps which are difficult to break apart
 Class-B
 Some cohesiveness
 Clumps which are easily broken or molded
 Class-C
 Loose soils
 Wet soils
OSHA Regulations




Applicable regulations
Methods of providing worker protection
Soil classifications
Soil classification tests
 OSHA requires
 Visual
at least one visual & one manual test
tests
• Observe spoil pile and its clumping behavior
• Observe sides and lip of trench for layers and tension cracks
• Watch for seeping water
• Determine likelihood of previously disturbed soil
 Manual
tests
• Thumb penetration test
• Pocket penetrometer
• Shearvane
OSHA Regulations





Applicable regulations
Methods of providing worker protection
Soil classifications
Soil classification tests
Adjustments to soil classification
 Wet
soils are always Class-C
Dangers of wet soils
Standing water undermines trench walls
Dangers of wet soils
Water table
Seeping water causes the soil to shift
OSHA Regulations





Applicable regulations
Methods of providing worker protection
Soil classifications
Soil classification tests
Adjustments to soil classification
 Wet
soils are always Class-C
OSHA Regulations





Applicable regulations
Methods of providing worker protection
Soil classifications
Soil classification tests
Adjustments to soil classification
 Wet
soils are always Class-C
 Soil classification must be lowered if:
 Layered soils slope toward the trench
Sloped, layered soils
Top soil
Sand
Clay
Trench must be classified to the worst soil layer
If layers slope toward the trench, class must also be dropped
OSHA Regulations





Applicable regulations
Methods of providing worker protection
Soil classifications
Soil classification tests
Adjustments to soil classification
 Wet
soils are always Class-C
 Soil classification must be lowered if:
 Layered soils slope toward the trench
OSHA Regulations





Applicable regulations
Methods of providing worker protection
Soil classifications
Soil classification tests
Adjustments to soil classification
 Wet
soils are always Class-C
 Soil classification must be lowered if:
 Layered soils slope toward the trench
 Fissures are present
Fissured soils
Top view
Side view
Soil classification must be lowered one level
OSHA Regulations





Applicable regulations
Methods of providing worker protection
Soil classifications
Soil classification tests
Adjustments to soil classification
 Wet
soils are always Class-C
 Soil classification must be lowered if:
 Layered soils slope toward the trench
 Fissures are present
OSHA Regulations





Applicable regulations
Methods of providing worker protection
Soil classifications
Soil classification tests
Adjustments to soil classification
 Wet
soils are always Class-C
 Soil classification must be lowered if:
 Layered soils slope toward the trench
 Fissures are present
 Soil has been previously disturbed
 Soil is subject to vibration
 Trench collapse rescues must be no better than Class-B
 Many rescue teams will operate as if all are Class-C
OSHA Regulations






Applicable regulations
Methods of providing worker protection
Soil classifications
Soil classification tests
Adjustments to soil classification
Other factors which will effect trench stability
 Exposure
to elements
 Long term trench is open >24 hours
 Superimposed loads
Superimposed loads
OSHA requires all superimposed loads to be no closer than 2 feet
from trench
Superimposed loads
Spoil piles are exceptionally dangerous superimposed loads
Superimposed loads
2’
OSHA requires the spoil pile to be at least 2’ from trench
Whenever possible, move the spoil pile further back to increase work
area, expose fissures, and reduce possible impact from spoil weight
OSHA Regulations






Applicable regulations
Methods of providing worker protection
Soil classifications
Soil classification tests
Adjustments to soil classification
Other factors which will effect trench stability
 Exposure
to elements
 Long term trench is open >24 hours
 Superimposed loads
 Underground utilities
 May require shoring of their own
 Surface encumbrances
 Will require a registered professional engineer
 Water removal
 Standing water must be removed
OSHA Regulations







Applicable regulations
Methods of providing worker protection
Soil classifications
Soil classification tests
Adjustments to soil classification
Other factors which will effect trench stability
Additional regulations for worker safety
 Escape
routes
 No more than 25 ft. travel distance
 If using a ladder, it must extend a few feet above the
trench and be secured
 Air quality monitoring
 Personal protective equipment
 Helmet, boots, reflective vests, eye protection...
 Impact protection
 Stop logs, warning devices, spotters
Course Content
Introduction
 Trench Rescue Hazards
 OSHA Regulations
 Protective Systems
 Shoring System Design
 Rescue Shoring
 Trench Rescue Operations

Course Content
Introduction
 Trench Rescue Hazards
 OSHA Regulations
 Protective Systems
 Shoring System Design
 Rescue Shoring
 Trench Rescue Operations

Protective systems

Sloping
 Must
slope to the angle of repose
 Angle depends on the soil classification
Sloping a trench
4’
8’
Class-A
8’
8’
Class-B
12’
8’
Class-C
Slope angle is determined by soil classification
Protective systems

Sloping
 Must
slope to the angle of repose
 Angle depends on the soil classification
 May incorporate steps or benches
 May be used in combination with shielding or shoring
Sloping a trench
Benching a trench
Using sloping with shielding/shoring
Protective systems

Sloping
 Must
slope to the angle of repose
 Angle depends on the soil classification
 May incorporate steps or benches
 May be used in combination with shielding or shoring
 Impractical in the Midwest due to width of opening
Sloping a trench
10’
23’
10’
3’
10’
Sloping is often impractical
Protective systems


Sloping
Shielding
 Strong
metal boxes which can hold back the force of
moving soil
 Typically assembled at the work site and maneuvered
into position with a backhoe
Shielding
Typical trench shield
Protective systems


Sloping
Shielding
 Strong
metal boxes which can hold back the force of
moving soil
 Typically assembled at the work site and maneuvered
into position with a backhoe
 Boxes must be designed for the trench dimensions and
the type of soil they are to be used in
 Worker must stay within the box to be protected
 Box must be positioned correctly:
 Must extend a few inches above the trench lip
 Must be no further than 2 ft. off bottom
Shielding
2’ max.
Proper positioning of a trench box
Shielding
Dangers of improper placement of a trench box
Protective systems



Sloping
Shielding
Shoring
 A support
system which is only strong enough to stop
dirt from starting to move
 Works by exerting pressure and resistance into the
trench walls creating arches of protection
Shoring
Shoring works by creating arches of protection
Protective systems



Sloping
Shielding
Shoring
 A support
system which is only strong enough to stop
dirt from starting to move
 Works by exerting pressure and resistance into the
trench walls creating arches of protection
 Shoring system components
 Simple shoring system
 Shoring system with wales
 Sheeting systems
Shoring
Upright
Crossbrace
Simple shoring system
Shoring
Upright
Crossbrace
Wale
Shoring system with wales
Allows for additional uprights or sheeting as required
Shoring
Close sheeting
Shoring
Tight sheeting
Shoring
Plywood sheeting
Not considered structural unless it is specified as part of an engineered system
OSHA requires 1 1/8” soft plywood or 3/4” 14-ply finland form
Protective systems



Sloping
Shielding
Shoring
 A support
system which is only strong enough to stop
dirt from starting to move
 Works by exerting pressure and resistance into the
trench walls creating arches of protection
 Shoring system components
 Simple shoring system
 Shoring system with wales
 Sheeting systems
 Types of shoring systems
 Timber
 Screwjack
 Pneumatic
 Hydraulic
Shoring
•OSHA has charts for construction
•Requires numerous large timbers
•Wood must be Douglas Fir or
mixed oak
•Difficult to find and store
•Must be custom cut at scene
•Requires installer to enter trench
•Pressurized with wooden wedges
Timber shoring
Shoring
4” x 6” x 14’ uprights
8” x 8” x 14’ walers
2” x 4” wedges
6” x 6” x 4’ crossbraces
2” x 2” blocks
Timbers required for 12’ length of 4’ wide, 10’ deep trench in Class-B soil
Shoring
•Difficult to find engineering tables
•Are often equipped with inadequate
pipe
•Must be custom cut at scene
•Requires installer to enter trench
•Pressurized by screwing jack out
•Must have feet installed
•Must not expose more than 1/2 of
the screw
Screwjack shoring
Shoring
•Most popular rescue strut
•Requires purchase of multiple lengths
for rescue
•Requires installer to enter trench
•Pressurized by air pressure, then
locked into place
•Requires timber components for
uprights and walers
•Manufacturer has engineering data to
help eliminate timber requirements
•Airshore & Paratech manufacturers
Pneumatic shoring
Shoring
•OSHA has design charts
•Requires purchase of multiple
lengths for rescue
•Bulky to store
•Pressurized by hydraulic hand
pump
•Only system which does not
require the installer to enter the
trench
•Difficult to use on uneven walls
•Allows greater depths without
walers
Hydraulic shoring
Protective systems



Sloping
Shielding
Shoring
 A support
system which is only strong enough to stop
dirt from starting to move
 Works by exerting pressure and resistance into the
trench walls creating arches of protection
 Shoring system components
 Simple shoring system
 Shoring system with wales
 Sheeting systems
 Types of shoring systems
 Timber
 Screwjack
 Pneumatic
 Hydraulic
Course Content
Introduction
 Trench Rescue Hazards
 OSHA Regulations
 Protective Systems
 Shoring System Design
 Rescue Shoring
 Trench Rescue Operations
