welcome corporate safety training 29 cfr 1926.650-653 trenching and shoring safety
TRANSCRIPT
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.
COURSE OBJECTIVES
APPLICABLE REGULATIONS
29 CFR 1926.650 - General Protection Requirements 29 CFR 1926.651 - Specific Excavation Requirements 29 CFR 1926.652 - Specific Trenching Requirements 29 CFR 1926.653 - Definitions Appendix - A - Excavations Appendix - B - Sloping and Benching Appendix - C - Timber Shoring for Trenches Appendix - D - Aluminum Hydraulic Shoring
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
PURPOSE OF THE 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!!!!!!
REASONS TO MAINTAIN AN EFFECTIVE PROGRAM:
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.
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
HOW MUCH DOES SOIL WEIGH?
DEPENDING ON THE DENSITY AND WATER CONTENT:
One cubic yard weighs - 3000lbs or more One cubic foot weighs - 100lbs or more
3000lbs or more
3 FEET
100lbs or more
1 FOOT
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
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
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
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
EMERGENCY PROCEDURES
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!
Continued
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
SURFACE ENCUMBRANCES
MUST BE: Removed Relocated Supported to protect site personnel
EXAMPLES INCLUDE:
Fencing Posts Telephone Cable Electrical Access Boxes
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
UNDERGROUND INSTALLATIONS
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!!!
Continued
STRUCTURAL RAMPS: USED ONLY BY PEOPLE DESIGNED BY A “COMPETENT PERSON”
EGRESS REQUIRED EVERY 25 FEET (LATERAL) > = 4FT
ACCESS AND EGRESS
TRENCHES MORE THAN 5 FEET:
Require shoring Or must have a stabilized slope
IN HAZARDOUS SOIL CONDITIONS:
Trenches under 5 feet need protection
TRENCH SAFETY
TESTING AND CONTROLS:
Oxygen deficiency Flammable atmospheres Testing
EMERGENCY RESCUE EQUIPMENT:
Availability Lifelines
HAZARDOUS ATMOSPHERES
SAFELINE
SAFELINE
BACK-UPFALL PROTECTION
WINCH
TRIPOD
TIE-OFF POINT
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
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
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
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
FALL PROTECTION
Guardrails must be provided for crossing over excavations
Barriers must be provided for remotely located excavations
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
SOIL CLASSIFICATION SYSTEM
SOIL CLASSIFICATION MUST BE DONE BY A COMPETENT PERSON:
Continued
Check entire worksite Fissured ground Layered soil Disturbed earth Seepage Vibration Poor drainage
VISUAL TEST
A B C
SOIL CLASSIFICATION SYSTEMContinued
Plasticity Dry Strength Thumb penetration Pocket penetrameter Hand operated shear vane
MANUAL TEST
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.
TYPE A SOILS
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
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
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
REQUIREMENTS FOR PROTECTIVE SYSTEMS
Each employee must be protected from cave-ins by an adequately designed system. Exceptions are:
Excavations made in stable rockExcavations less than 5 feet
Protective systems must have the capacity to resist all loads that are expected to be applied to the system
DESIGN OF BENCHING AND SLOPING SYSTEMS:
– OPTION 1 - Allowable configurations and slopes
– OPTION 2 - Determination of slopes and configurations using 29 CFR 1926.652
– OPTION 3 - Designs using other tabulated data
– OPTION 4 - Design by a registered professional engineer
Continued
REQUIREMENTS FOR PROTECTIVE SYSTEMS
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
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
INSTALLATION AND REMOVAL OF SUPPORT
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
Continued
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
SLOPING AND BENCHING SYSTEMSContinued
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.
SLOPING AND BENCHING SYSTEMSContinued
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.
TYPE B
34 DegreesMaximum
53 DegreesMaximum
45 DegreesMaximum
90 Degrees
TYPE A
TYPE C
STABLE ROCK
SLOPING AND BENCHING SYSTEMSContinued
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
ContinuedSHORING SYSTEMS
REMOVAL
Remove shoring from the bottom up Pull sheeting out from above Backfill immediately after removal of support system
ContinuedSHORING SYSTEMS
WALES
SHEETING
JACKS/CROSSBRACES
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
SHIELD SYSTEMS
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
Continued
SHIELD SYSTEMS
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
Continued