1. Risk Management Department
Site Safety Teams
4/14/2017
Risk Management Department
Excavation
Safety
May, 2008
Risk Management Department

2. Excavation Safety Introduction
Site Safety Teams
4/14/2017
Excavation Safety
Introduction
In order to prevent injuries and improve work productivity, APS has developed this training to provide you the knowledge to stay safe when working in and around excavations.
Risk Management Department

3. Excavation Safety Introduction
Site Safety Teams
4/14/2017
Excavation Safety
Introduction
About 400 U.S. workers die in trench-related accidents each year
About 6,400 are seriously injured
For this reason it is important to understand how to stay safe in and around excavations
Risk Management Department

4. Excavation Safety Introduction In this training we will cover:
Site Safety Teams
4/14/2017
Excavation Safety
Introduction
In this training we will cover:
What is a trench?
Soil characteristics
Collapse types
Shoring techniques
Safety requirements
Risk Management Department

5. Excavation Safety What is a Trench?
Site Safety Teams
4/14/2017
Excavation Safety
What is a Trench?
A narrow excavation that is deeper than it is wide
No more than 15 feet wide at bottom
Walls will eventually fail
Risk Management Department

6. Excavation Safety What is a Trench?
Site Safety Teams
4/14/2017
Excavation Safety
What is a Trench?
Failure of trench walls results in cave-in:
Soil or rock that suddenly falls or slides into an excavation
Sufficient quantity to entrap, bury, injure, or immobilize
Soil gravitates downward, pressure pushes soil inward toward the trench
Bottom third of wall typically fails first
Soil above the collapsed lower wall follows
Risk Management Department

7. Excavation Safety What is a Trench? Cave-ins are dangerous to workers:
Site Safety Teams
4/14/2017
Excavation Safety
What is a Trench?
Cave-ins are dangerous to workers:
Soil weighs 125 lbs. per cubic foot
A worker can be crushed by soil, rock, or an object
Suffocation—even if worker’s head is not buried, soil prevents chest expansion
Worker becomes immobilized by soil’s suction effect
Risk Management Department

8. Excavation Safety Soil Characteristics
Site Safety Teams
4/14/2017
Excavation Safety
Soil Characteristics
Type A (most stable) — dense and heavy clay
Type B — silt, sandy loam, medium clay
Type C (least stable) — gravel, loamy sand, soft clay
Risk Management Department

9. Excavation Safety Soil Characteristics
Site Safety Teams
4/14/2017
Excavation Safety
Soil Characteristics
Factors affecting soil strength:
Water
Vibrations
Erosion and Weathering
Excavation Depth
Slope Steepness
Degree of Soil Compaction
Risk Management Department

10. Excavation Safety Soil Characteristics Signs of impending collapse:
Site Safety Teams
4/14/2017
Excavation Safety
Soil Characteristics
Signs of impending collapse:
Fissures or cracks on excavation face
Slumping of material from excavation face
Bulging or heaving of material at the bottom of excavation wall
Sinking of excavation’s edge
Ravelling, or small amounts of material (e.g., pebbles) trickling into excavation
Risk Management Department

11. Excavation Safety Collapse Types
Site Safety Teams
4/14/2017
Excavation Safety
Collapse Types
There are four types of trench collapses:
Spoil Pile Slide
Side Wall Shear
Slough–in
Rotation
Risk Management Department

12. Excavation Safety Collapse Types Spoil Pile Slide -
Site Safety Teams
4/14/2017
Excavation Safety
Collapse Types
Spoil Pile Slide -
Collapse of material that has
been removed from the trench
back into the trench
Risk Management Department

13. Excavation Safety Collapse Types Side Wall Shear -
Site Safety Teams
4/14/2017
Excavation Safety
Collapse Types
Side Wall Shear -
Collapse of side wall
from the top into trench
Risk Management Department

14. Excavation Safety Collapse Types Slough-in - from middle of wall
Site Safety Teams
4/14/2017
Excavation Safety
Collapse Types
Slough-in -
Collapse of side wall
from middle of wall
Risk Management Department

15. Excavation Safety Collapse Types Rotation - Collapse of bottom third
Site Safety Teams
4/14/2017
Excavation Safety
Collapse Types
Rotation -
Collapse of bottom third
of trench wall causing
secondary wall collapse
Risk Management Department

16. Excavation Safety Shoring Techniques
Site Safety Teams
4/14/2017
Excavation Safety
Shoring Techniques
Engineers are often required to design shoring, which is a construction procedure used specifically to maintain the stability of the walls of an excavation and provide protection to workers who may enter the excavation
Risk Management Department

17. Excavation Safety Shoring Techniques
Site Safety Teams
4/14/2017
Excavation Safety
Shoring Techniques
To mitigate the danger of cave-ins, there are 4 main techniques
to shore trench walls:
Wood Support
Screw Jacks
Hydraulic Shores
Trench Cages
Risk Management Department

18. Excavation Safety Shoring Techniques Wood Support Site Safety Teams
4/14/2017
Excavation Safety
Shoring Techniques
Wood Support
Risk Management Department

19. Excavation Safety Shoring Techniques Screw Jacks Site Safety Teams
4/14/2017
Excavation Safety
Shoring Techniques
Screw Jacks
Risk Management Department

20. Excavation Safety Shoring Techniques Hydraulic Shores
Site Safety Teams
4/14/2017
Excavation Safety
Shoring Techniques
Hydraulic Shores
Risk Management Department

21. Excavation Safety Shoring Techniques Trench Cages Site Safety Teams
4/14/2017
Excavation Safety
Shoring Techniques
Trench Cages
Risk Management Department

22. Site Safety Teams
4/14/2017
Excavation Safety
Safety Requirements
At least one worker in each work crew must be experienced in the type of work being performed in excavations
At least one worker should be trained in first aid
Risk Management Department

23. Excavation Safety Safety Requirements
Site Safety Teams
4/14/2017
Excavation Safety
Safety Requirements
Protecting the area around the excavation:
All work areas must be adequately guarded or barricaded by fences, guardrails or a covering sufficient to prevent persons from falling into the excavation
Excavations might endanger stability of buildings, walls, other structures
Sidewalks, pavement not undermined
unless supported to prevent collapse
on excavation workers
Risk Management Department

24. Excavation Safety Safety Requirements
Site Safety Teams
4/14/2017
Excavation Safety
Safety Requirements
Protecting workers in excavations:
Protect workers from loose rock/soil that may fall from an excavation face
Use scaling to remove loose soil
Use protective barricades, such as shoring or shields
Protect workers from material or equipment that could fall into the excavation
Keep material/equipment at least
3 feet from edge
Use retaining devices
Risk Management Department

25. Excavation Safety Safety Requirements
Site Safety Teams
4/14/2017
Excavation Safety
Safety Requirements
Protecting workers in excavations:
Excavation sites cannot be covered with anything such as piles of excavated material or excavation equipment which might accidentally fall into the excavation
Risk Management Department

26. Excavation Safety Safety Requirements
Site Safety Teams
4/14/2017
Excavation Safety
Safety Requirements
Protecting workers in excavations:
Trenches 4 feet deep or more must have exit means within 25 feet of every worker
Use fall protection
Do not work on sides of sloped or benched excavation above other workers
For parallel construction have a worker on top to watch excavation walls to warn trench workers of potential hazards
Risk Management Department

27. Excavation Safety You are finished!
Site Safety Teams
4/14/2017
Excavation Safety
You are finished!
You have finished the Excavation Safety training.
Download the quiz from the Risk Management website’s training page.
Print the form and be sure to write your name, location and employee number in the spaces provided.
Complete the ten questions and have your supervisor send it to the Risk Management office
Risk Management Department