1. CORPORATE SAFETY TRAINING
TRENCHING AND SHORING SAFETY
CORPORATE SAFETY TRAINING
29 CFR
WELCOME 1

2. COURSE OBJECTIVES Introduce The Trenching & Shoring Safety Program
Establish The Programs Role.
Discuss the components of an effective program.
Introduce ideas to help develop an effective program.
Introduce Basic Skills in the Recognition & Control of Trenching & Shoring Hazards. 3

3. APPLICABLE REGULATIONS
29 CFR General Protection Requirements
29 CFR Specific Excavation Requirements
29 CFR Specific Trenching Requirements
29 CFR Definitions
Appendix - A - Excavations
Appendix - B - Sloping and Benching
Appendix - C - Timber Shoring for Trenches
Appendix - D - Aluminum Hydraulic Shoring 7

4. BASIS FOR THE REGULATIONS
Hundreds of workers killed annually from cave-ins
Thousand of workers injured annually from cave-ins
Fatality rate for trenching is twice the level for general
construction 8

5. PURPOSE OF THE PROGRAM Peace of mind Reduced liability
REASONS TO MAINTAIN AN EFFECTIVE PROGRAM:
Peace of mind
Reduced liability
Increased productivity
Reduced lost man-hours
Improved employee morale
Reduced or eliminated fines
Improved health of employees
Reduced injury and illness rates
Lower workers’ compensation costs
Because it’s the right thing to do!!!!!! 12

6. MECHANISM OF DEATH Asphyxiation
Each time a breath is exhaled the weight of the load restricts inhalation of the next breath. Slow suffocation usually follows unless rescue is immediate. 13

7. DYNAMIC SITE CONDITIONS
CAVE-INS RESULT FROM:
Vibrations
Adjacent Structures
Freezing and Thawing
The Weight of the Soil Itself
Addition or Removal of Water
Reduction in Frictional and Cohesive Capacities of Soil 14

8. HOW MUCH DOES SOIL WEIGH?
DEPENDING ON THE DENSITY AND WATER CONTENT:
One cubic yard weighs lbs or more
One cubic foot weighs - 100lbs or more
3000lbs or more
3 FEET
100lbs or more
1 FOOT 15

9. HOW DO MOST DEATHS OCCUR?
Instantaneously
Trenches 5 to 15 deep
With absolutely no warning
In seemingly safe conditions
With workers in a bent or lying position 16

10. SITE EVALUATION BEFORE YOU BEGIN EXCAVATION: The site must be assessed
Potential hazards must be determined
Known hazards reduced or eliminated
Emergency procedures established
Periodic inspection intervals determined
Utility locations must be staked or marked 17

11. BASIC SAFETY REQUIREMENTS
Conduct inspections before each work shift
Do not travel under elevated loads
Do not work over unprotected employees
Wear proper personal protective equipment
Provide walkways or bridges over trenches
Provide trench exits within 25 feet of workers in
trenches more than four feet deep
Ensure spoilage is at least 2 ft. from trench edges 18

12. EMERGENCY PROCEDURES
Immediately call 911, or the Emergency Response Team
Report: - Exact Location
- Number of Victims
- Nature of Emergency
- Trench Measurements
- Special Hazards
Keep all life-support and dewatering systems operating
Clear workers away from the excavation
Shut down heavy equipment
Be prepared to meet and brief rescue personnel 19

13. EMERGENCY PROCEDURES What not to do: - Don’t Panic!
Continued
What not to do: - Don’t Panic!
- Control would-be rescuers
- Don’t sacrifice anyone else
- Never attempt to dig someone out
using motorized equipment
Remember - Your actions could save a life! 20

14. FOOT AND VEHICLE TRAFFIC
ACCIDENT PREVENTION METHODS:
Warn and reroute public traffic
Post signs, barricades and flagmen
Mandate use of reflective vests
Warn site traffic with stoplogs etc.
Install protective supports systems 21

15. SURFACE ENCUMBRANCES MUST BE: Removed Relocated
Supported to protect site personnel
EXAMPLES INCLUDE:
Fencing
Posts
Telephone
Cable
Electrical Access Boxes 22

16. UNDERGROUND INSTALLATIONS
Utility lines must be located before excavating begins
Utility companies or owners must be contacted:
-- Response times must be considered
-- Advised of the proposed work
-- Questioned concerning underground installations
need to be answered 23

17. UNDERGROUND INSTALLATIONS
Continued
If no response is given within 24 hours* work can
cautiously proceed *(local timeframes may vary)
Underground installations must be determined by
safe and acceptable means
Excavated underground installations must be
protected
Never under estimate hazards associated with
underground utilities!!! 24

18. ACCESS AND EGRESS STRUCTURAL RAMPS: USED ONLY BY PEOPLE
DESIGNED BY A “COMPETENT PERSON”
EGRESS REQUIRED EVERY 25 FEET (LATERAL) > = 4FT 25

19. TRENCH SAFETY TRENCHES MORE THAN 5 FEET: Require shoring
Or must have a stabilized slope
IN HAZARDOUS SOIL CONDITIONS:
Trenches under 5 feet need protection 26

20. HAZARDOUS ATMOSPHERES
TESTING AND CONTROLS:
Oxygen deficiency
Flammable atmospheres
Testing
EMERGENCY RESCUE EQUIPMENT:
Availability
Lifelines
SAFELINE
BACK-UP
FALL PROTECTION
WINCH
TRIPOD
TIE-OFF POINT 27

21. HAZARDS & WATER ACCUMULATION
Adequate Precautions Must Be Taken When Working in Accumulated Water
Controlling Water and Water Removal Must Be Monitored by a Competent Person
Ditches, Dikes or Comparable Means Should Be Used to Prevent Surface Water From Entering Excavations 28

22. WEATHER FACTORS Don’t under estimate the effects weather can have
Weather can have a drastic effect on the site
Daily (or hourly) site inspections must be made
Consider protection from:
Lightning
Flooding
Erosion
High winds
Hot or Cold Temperatures 29

23. STABILITY OF ADJACENT STRUCTURES
When stability is endangered
support systems must be used.
Excavation below the base of a
foundation will not be permitted
when it poses a hazard except
when:
A support system is provided
The excavation is in stable rock
A registered professional has approved the site or deemed the situation will not pose a hazard 30

24. SITE INSPECTIONS Daily inspections must be made by a competent
person of:
When evidence is found of a hazardous condition, the
exposed employees must be Immediately removed
from the area.
Excavations
Adjacent areas
Protective systems 31

25. FALL PROTECTION
Guardrails must be provided for crossing over excavations
Barriers must be provided for remotely located excavations 32

26. SOIL CLASSIFICATION SYSTEM
TYPE A SOILS
- Clay
- Silty Clay
- Sandy Clay
- Clay Loam
TYPE B SOILS
- Granular Cohesionless Soils (Silt Loam)
TYPE C SOILS
- Gravel
- Sand
- Loamy Sand 33

27. SOIL CLASSIFICATION SYSTEM
Continued
SOIL CLASSIFICATION MUST BE DONE BY A
COMPETENT PERSON:
VISUAL TEST
Check entire worksite
Fissured ground
Layered soil
Disturbed earth
Seepage
Vibration
Poor drainage A B C 34

28. SOIL CLASSIFICATION SYSTEM
Continued
MANUAL TEST
Plasticity
Dry Strength
Thumb penetration
Pocket penetrameter
Hand operated shear vane A B C
WARNING: One soil inspection and classification may not be enough. Outside disturbances during excavation may change even the best soil classification. Inspect the soil after any change in conditions. 35

29. TYPE A SOILS A B C Are cohesive soils with an unconfined,
compressive strength of 1.5 t/sf.
Clues that soil is not type A:
If it is fissured
If it is subject to vibration
If it has been previously disturbed
If the soil is part of a sloped, layered system
If the material is subject to other factors that would require it to be classified as a less than stable material A B C 36

30. TYPE B SOILS
Are cohesive soils with an unconfined compressive strength greater than 0.5 t/sf
Types include angular gravel, silt, silt loam, sandy loam and silty clay loam
Previously disturbed soils except those which would be classified as type C
Dry rock that is not stable A B C 37

31. TYPE C SOILS
Are cohesive soil with an unconfined compressive strength of .5 t/sf
Are granular soils including gravel, sand, and loamy sand
Submerged soil or soil from which water is seeping
Submerged rock that is not stable A B C 38

32. REQUIREMENTS FOR PROTECTIVE SYSTEMS
Each employee must be protected from cave-ins by an adequately designed system. Exceptions are:
Excavations made in stable rock
Excavations less than 5 feet
Protective systems must have the capacity to resist all loads that are expected to be applied to the system 39

33. REQUIREMENTS FOR PROTECTIVE SYSTEMS
Continued
DESIGN OF BENCHING AND SLOPING SYSTEMS:
OPTION 1 - Allowable configurations and slopes
OPTION 2 - Determination of slopes and configurations
using 29 CFR
OPTION 3 - Designs using other tabulated data
OPTION 4 - Design by a registered professional engineer 40

34. MATERIALS AND EQUIPMENT
Must be free from damage or defects that might impair proper function
Must be used and maintained in a manner that is consistent with the recommendations of the manufacturer
Must be examined by a competent person if damage occurs 41

35. INSTALLATION AND REMOVAL OF SUPPORT
GENERAL REQUIREMENTS
Support systems must be securely connected
Support systems must be installed and removed in a manner that protects from collapse
Support systems must not be subjected to loads exceeding design specifications 42

36. INSTALLATION AND REMOVAL OF SUPPORT
Continued
GENERAL REQUIREMENTS
Additional precautions must be taken to ensure safety before temporary removal begins
Removal must begin at the bottom of the excavation
Backfilling must progress together with the removal of support systems from excavations 43

37. SLOPING AND BENCHING SYSTEMS
EMPLOYEES MUST NOT BE PERMITTED TO WORK:
On the faces of sloped or benched excavations
At levels above other employees except when employees at the lower levels are adequately protected from the hazard of falling, rolling or sliding material or equipment 44

38. SLOPING AND BENCHING SYSTEMS
Continued
TEMPORARY SPOIL PILES:
2 FEET MINIMUM 45

39. SLOPING AND BENCHING SYSTEMS
Continued
SLOPING GENERAL REQUIREMENTS
Various slope angles are allowed by OSHA
Appendix B to 1926 Subpart P must be consulted
Evacuate the excavation if walls show signs of distress
If soil conditions change, re-inspect. 46

40. SLOPING AND BENCHING SYSTEMS
Continued
BENCHING GENERAL REQUIREMENTS
Various slope angles are allowed by OSHA
Appendix B to 1926 Subpart P must be consulted
Evacuate the excavation if walls show signs of distress
If soil conditions change, re-inspect. 47

41. SLOPING AND BENCHING SYSTEMS
Continued
TYPE B
34 Degrees
Maximum
53 Degrees
45 Degrees
90 Degrees
TYPE A
TYPE C
STABLE ROCK 48

42. BENCHING EXAMPLE 20
FEET
MAX
3/4 1
TYPE A SOILS 49

43. SLOPING EXAMPLE 20
FEET
MAX 1
TYPE B SOILS 50

44. SHORING SYSTEMS
WALES
SHEETING
JACKS/CROSSBRACES 51

45. SHORING SYSTEMS GENERAL OSHA TABLES PROVIDE SHORING DATA
Continued
GENERAL
Shoring provides a framework to work in
Shoring uses wales crossbraces and uprights
Shoring supports excavation walls
OSHA TABLES PROVIDE SHORING DATA
Soil type must be known
Depth and width of the excavation must be known
You must be familiar with the OSHA Tables 52

46. SHORING SYSTEMS REMOVAL Remove shoring from the bottom up
Continued
REMOVAL
Remove shoring from the bottom up
Pull sheeting out from above
Backfill immediately after removal of support system
WALES
SHEETING
JACKS/CROSSBRACES 53

47. SHORING SYSTEMS
Continued
PNEUMATIC/
HYDRAULIC
JACKS
SCREW
JACK 54

48. SHIELD SYSTEMS GENERAL
Shield systems must project at least 18 inches above the lowest point where the excavation face begins to slope
At Least 18 Inches 55

49. SHIELD SYSTEMS GENERAL
Continued
GENERAL
Shield systems must not be subjected to loads exceeding those which the system was designed to withstand
Shields must be installed to restrict hazardous movement
Employees must be protected from the hazard of cave-ins when entering or exiting the areas protected by shields
Employees must not be allowed in shields when shields are being installed, removed, or moved vertically 56

50. SHIELD SYSTEMS
Continued
COMMON TRENCH SHIELD 57

51. SHIELD SYSTEMS Systems may be connected Systems may be stacked
Continued
Systems may be connected
Systems may be stacked
Configuration must by consistent
with the recommendations of the
manufacturer
Must be examined by a competent
person if damage occurs 58

52. TIPS FOR USING CONTRACTORS
REMEMBER, YOU CONTROL YOUR SITE!
REVIEW THEIR PROCEDURES WITH THEM BEFORE
STARTING THE JOB!
DETERMINE THEIR SAFETY PERFORMANCE RECORD!
DETERMINE WHO IS IN CHARGE OF THEIR PEOPLE!
DETERMINE HOW THEY WILL AFFECT YOUR EMPLOYEES! 59