Trench Awareness

1
Trench Awareness

• presented by the
• Office of the State Fire Marshall of Illinois

2
Course Content

• Introduction
• Trench Rescue Hazards
• OSHA Regulations
• Protective Systems
• Shoring System Design
• Rescue Shoring
• Trench Rescue Operations

3
Course Content

• Introduction
• Trench Rescue Hazards
• OSHA Regulations
• Protective Systems
• Shoring System Design
• Rescue Shoring
• Trench Rescue Operations

4
Introduction

• OSFM technical rescue certifications
• Definition of a trench
• Trenching operations
• Trench accidents and statistics

5
Introduction

• OSFM technical rescue certifications
• Definition of a trench
• Trenching operations
• Trench accidents and statistics

6
OSFM Technical Rescue Specialist Certifications
7
Introduction

• OSFM technical rescue certifications
• Definition of a trench
• Trenching operations
• Trench accidents and statistics

8
Introduction

• OSFM technical rescue certifications
• Definition of a trench
• Trenching operations
• Trench accidents and statistics

9
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.

10
Introduction

• OSFM technical rescue certifications
• Definition of a trench
• Trenching operations
• Trench accidents and statistics

11
Introduction

• OSFM technical rescue certifications
• Definition of a trench
• Trenching operations
• Trench accidents and statistics

12
Trenching operations

• OSHA protection requirements are often ignored
• Contractors are often family businesses

13
Trenching operations

• OSHA protection requirements are often ignored
• Contractors are often family businesses

14
Trenching operations

• OSHA protection requirements are often ignored
• Ignorance/complacency of risks
• Economic factors
• Contractors are often family businesses

15
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

16
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

17
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

18
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

19
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

20
Introduction

• OSFM technical rescue certifications
• Definition of a trench
• Trenching operations
• Trench accidents and statistics

21
Introduction

• OSFM technical rescue certifications
• Definition of a trench
• Trenching operations
• Trench accidents and statistics

22
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

23
Introduction

• OSFM technical rescue certifications
• Definition of a trench
• Trenching operations
• Trench accidents and statistics

24
Course Content

• Introduction
• Trench Rescue Hazards
• OSHA Regulations
• Protective Systems
• Shoring System Design
• Rescue Shoring
• Trench Rescue Operations

25
Course Content

• Introduction
• Trench Rescue Hazards
• OSHA Regulations
• Protective Systems
• Shoring System Design
• Rescue Shoring
• Trench Rescue Operations

26
Trench Rescue Hazards

• Hazards are not obvious

• Trenches dont 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

27
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

28
Types of collapses
Slough-in
Sidewall-in Shear-in
Spoil-in
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How rescuers become victims
30
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

31
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

32
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

33
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

34
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

35
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

36
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

37
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

38
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

39
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

40
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

41
Course Content

• Introduction
• Trench Rescue Hazards
• OSHA Regulations
• Protective Systems
• Shoring System Design
• Rescue Shoring
• Trench Rescue Operations

42
Course Content

• Introduction
• Trench Rescue Hazards
• OSHA Regulations
• Protective Systems
• Shoring System Design
• Rescue Shoring
• Trench Rescue Operations

43
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

44
OSHA Regulations

• Applicable regulations

• Methods of providing worker protection

• Sloping
• Shoring
• Shielding

45
Methods of providing worker protection
Sloping
Shoring
Shielding
46
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

47
OSHA Regulations

• Applicable regulations

• Methods of providing worker protection

• Soil classifications

• Soil classification tests

• OSHA requires at least one visual one manual
  test
• Visual 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

48
OSHA Regulations

• Applicable regulations

• Methods of providing worker protection

• Soil classifications

• Soil classification tests

• Adjustments to soil classification

• Wet soils are always Class-C

49
Dangers of wet soils
Standing water undermines trench walls
50
Dangers of wet soils
Water table
Seeping water causes the soil to shift
51
OSHA Regulations

• Applicable regulations

• Methods of providing worker protection

• Soil classifications

• Soil classification tests

• Adjustments to soil classification

• Wet soils are always Class-C

52
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

53
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
54
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

55
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

56
Fissured soils
Top view
Side view
Soil classification must be lowered one level
57
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

58
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

59
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 gt24 hours
• Superimposed loads

60
Superimposed loads
OSHA requires all superimposed loads to be no
closer than 2 feet from trench
61
Superimposed loads
Spoil piles are exceptionally dangerous
superimposed loads
62
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
63
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 gt24 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

64
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

65
Course Content

• Introduction
• Trench Rescue Hazards
• OSHA Regulations
• Protective Systems
• Shoring System Design
• Rescue Shoring
• Trench Rescue Operations

66
Course Content

• Introduction
• Trench Rescue Hazards
• OSHA Regulations
• Protective Systems
• Shoring System Design
• Rescue Shoring
• Trench Rescue Operations

67
Protective systems

• Sloping

• Must slope to the angle of repose
• Angle depends on the soil classification

68
Sloping a trench
4
8
12
8
8
8
Class-A Class-B
Class-C
Slope angle is determined by soil classification
69
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

70
Sloping a trench
Benching a trench
Using sloping with shielding/shoring
71
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

72
Sloping a trench
23
10
10
10
3
Sloping is often impractical
73
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

74
Shielding
Typical trench shield
75
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

76
Shielding
2 max.
Proper positioning of a trench box
77
Shielding
Dangers of improper placement of a trench box
78
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

79
Shoring
Shoring works by creating arches of protection
80
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

81
Shoring
Upright
Crossbrace
Simple shoring system
82
Shoring
Upright
Crossbrace
Wale
Shoring system with wales Allows for additional
uprights or sheeting as required
83
Shoring
Close sheeting
84
Shoring
Tight sheeting
85
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
86
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

87
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
88
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
89
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
90
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
91
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
92
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

93
Course Content

• Introduction
• Trench Rescue Hazards
• OSHA Regulations
• Protective Systems
• Shoring System Design
• Rescue Shoring
• Trench Rescue Operations