Excavation Safety

Excavation

- It is any man-made cut, cavity or depression in an earth surface that is formed by earth removal.

 Trench

- It is a narrow excavation where the depth is greater than its width, and the width measured at the bottom
is not greater than 15 ft.

Hazards of Excavation Works

• Soil Collapse
• Falls
• Vehicular Traffic
• Underground Utilities
• Working Surface
• Confined Space Conditions

Principal Causes of Soil Collapse

• Steep cutting angle
• Super imposed load
• Shock & Vibration
• Water Pressure
• Drying

Types of Soil

• Type A – Most stable: clay
• Type B – Medium stability: silt and unstable rock (disturbed soil as type B)
• Type C – Least stable: gravel, loamy sand, submerged soil, soil from which water is freely seeping.
• Stable Rock – solid mineral matter that can be excavated with vertical sides and remain intact while                                      exposed

Prevention of Soil Collapse

1. Cutting of the slope at a safe angle (H:V)
     • Type A - 3/4:1 or 53°
     • Type B - 1:1 or 45°
     • Type C - 1½ :1 or 34°

2. Provision of Shoring

Prevention of Falls

1. Provision of a safe distance from the edge of excavation or berm

* Minimum Berm
- not less than one third of the depth of the excavation
- may be reduced to not less than 1 meter provided that materials excavated are stable, shoring is designed to carry the additional load and barriers are present.

2.  Observance of a safe distance

- Tools or materials shall be kept a minimum of one meter away from the edge of the excavation
- Vehicles or machinery must maintain a distance of at least one third of the depth of the excavation from the    edge

3. Provision of barricades and signs

- Barricades should be at least one meter high
- Signs should be posted to provide warning to the workers and the public

4. Provision of walkways or bridges for crossing of trenches

- Minimum clear width of 20 inches
- With standard rails
- Extended to a minimum of 24 inches past the surface edge

5. Means of Access and Escape

- Shall be provided for every excavation over 1 meter deep
- At least one ladder in every 16.6 meters of length of excavation or fraction thereof
- A handhold shall extend at least 0.83 m from the top of the excavation

Vehicular Traffic

• Provide workers with warning vests or other suitable garments marked with reflectorized materials
• Designate a trained flag person along with signs and barricades when necessary
• Use horn or give signals to ensure safety.

Underground Utilities

• Determine location of underground facilities, deactivate if necessary and take necessary steps to prevent damage to these facilities.
• In an open excavation, support, protect or remove underground installation.

Working Surface

• Excavation shall be kept free of water at all times.
  –Canal or Dikes
  –Sump Pumping
  –Well Pointing
• In muddy areas, workers should be provided with boots to reduce the hazard of slipping.

Confined Space Conditions

Hazardous Atmosphere:
• Oxygen, O2 : < 19.5% or > 23.5%
• Flammable gas concentration > 10% of Lower Flammability Limit (LFL)
• Hazardous toxic chemicals

> Excavation in confined space
– Check the condition of the atmosphere before entry
– Do not work alone in a confined space
– Provide lifeline
– Provide ventilation or blower before entering
– Provide emergency rescue equipment such as breathing apparatus, safety harness and line and basket            stretcher

Working in Excavation

• Prior to opening
   - Check excavation permit
   - Identify all underground installations
   - Remove trees, boulders, stumps, other surface encumbrances and hazards before starting excavation

• During operations
   - Wear appropriate PPE
   - Give special attention to side slopes that are adversely affected by weather, moisture content or vibration
   - Safe working distance between workers
    - Maintain guardrails, fences, or other barricades and warning lights

• During break time, workmen should never stand or take rest on high banks of soft material
• Do not leave tools, materials, or debris in walkways, ramps, or near the edge of excavations
• Do not use guardrails as resting place

Inspection

• Daily before start of each shift
• After heavy rain
• When fissures, tension cracks, undercutting, water seepage, bulging at the bottom or other conditions occur
• When there is any indication of change or movement in adjacent structures or spoil pile

Summary

  • Remember:
       – An excavation may not be safe to enter without a proper support structure being provided.
       – Back-filled ground are especially dangerous.
       – Water increases the possibility of a cave in.
       – Excavation should be considered as a confined space.
       – A worker does not have to be completely buried in soil to be seriously v injured or killed.

Thank You!

Accident Causes and Prevention

Objectives

◦ Learn to identify the causes of accidents; and
◦ Enumerate systems to control unsafe acts and unsafe conditions

What is NEAR-MISS?

An unexpected event, which under slightly different circumstances, COULD HAVE RESULTED in harm to people, cause damage or loss to properties.

What is Accident?

Accident is an event that is unexpected, unplanned and unwanted that results in harm to people, cause damage or loss to properties.

Types of Accident

•Struck against rigid structure or sharp objects
•Struck by falling or flying objects, sliding or moving parts
•Caught in between objects
•Fall on same level
•Fall on different levels
•Electrocution
•Fire

Accident Theory

Causes of Accidents

• Unsafe Act
 > Performance of a task or other activity in a manner that may threaten the health and/or safety of workers.

Accidents Happen Because of Common Negative Mindsets of Workers About Safety
• Accidents are part of the job
• Accidents can happen but only to other people
• If something is really dangerous, the danger can be clearly seen and avoided
• Its my life so how I work is my business
• As long as I am careful I will be fine
• Taking risks is a sign of courage and bravery

Factors Contributing to Unsafe Acts
• Improper Attitudes
• Physical Limitations
• Inadequate Knowledge or Skills

Improper Attitudes
• Operating Equipment without Authority
• Disregard of SOP or instructions
• Removing Safety Devices
• Using Defective equipment
• Using improper PPEs
• Using PPEs improperly
• Horseplay
•Working in an unsafe posture
• Absent-mindedness / Nervousness
• Willful intent to injure
• Working while under the influence of alcohol or drugs

• Improper lifting and carrying

Physical Limitations
• Defective eyesight
• Muscular weakness due to fatigue
• Impaired hearing

Lack of Knowledge or Skill
• Failure to understand instruction
• Unaware of safe practices
• Unconvinced of safe practices
• Unskilled or unpracticed

• Unsafe Condition
 > The potential of a material, equipment, environment or process to cause harm.

Examples of Unsafe Conditions
• Wet slippery floors
• Unstable stacking of materials
• Protruding re-bars
• Live conductors without insulation
• Equipment without guarding
• Poor storage of combustible materials

Why Accidents Happened?

Generally, an accident happens because of an unsafe act of a worker in the presence of one or several unsafe conditions.

Can Accidents be Prevented?

Systems to Control Unsafe Act
> Education and Training
- Safety Orientation
- Job Instructions
> Visual Awareness
- Posters, Signs, Bulletin Board
> Tool Box Meeting
- A 10-15 minute on-the-job meetings

Controlling Unsafe Conditions

I. Identify the Hazards
• No provisions of lifelines
• Unstable Scaffolds
• Defective hand tools
• Accumulation of combustible materials
• Unsafe electrical connections

Systems to Control Unsafe Conditions
a. Eliminate
- Elimination of a specific hazard or hazardous work process is the most effective method of control. Maintaining good housekeeping in the workplace eliminates tripping and slipping hazards. Not using defective tools
b. Substitute
c. Isolate
- Machines should be designed with the correct guard on them to eliminate the danger of a worker getting caught in the machine while using it.
d. Engineering Control
- It include all control measures that remove or isolate a hazard from the workplace.
e. Admin Control
- Adopting standard operating procedures (SOPs) or safe work practices or providing appropriate training, instruction or information to prevent or limit worker’s exposure to hazards.
f. PPE
- to be used are determined by hazards identified in hazard analysis. PPE should only be used when all other hazard controls have been exhausted or more significant hazard controls are not feasible.

Occupational Safety
- is the identification and evaluation of unsafe acts/conditions and the application of control measures to prevent harm to people or minimize losses to properties.

Summary:
• Accident is a result of an unsafe act in the presence of one or several unsafe conditions
• Accident can be prevented by improving OSH knowledge, having right work attitude, doing best practices and applying available control measures against hazards in the workplace.

Thank you!

ACCIDENT INVESTIGATION

ACCIDENT INVESTIGATION

• A methodical effort to collect and interpret the facts of accident.
• An inquiry as to how and why the accident occurred in order to explore actions that should be taken to
prevent or minimize recurrence of the accident.
•Most important thing- Investigation is not intended to place blame.

Purposes of Accident Investigation

• To establish all facts
• To draw conclusion
• To make recommendations
• To prevent recurrence

Principles of Accident Investigation

The investigation of any accident event will never progress unless that event is first properly reported to the appropriate management within an organization.

Reasons Why Accidents Are Not Reported

• Natural fear many people have of being associated with an accident event.
• Idea of investigating a situation that has resulted in some degree of loss
• Reflect unfavorably on their own performance or that of their department.
• Simply do not wish to interrupt work production

Types of Accident to be Reported

• Fatal Accidents
• Accidents resulting to injuries
• Diseases/Illnesses
• Dangerous occurrences
• Near misses

Advantages of Having the Supervisor as the Accident Investigator

• More familiar with the people involved.
• Have a better understanding of the process or operation.
• Know all safe work practices/rules pertaining to his/her job
• Employees may be willing to speak more freely.

Who Should Conduct Accident Investigation?

 Safety Officer/Man
• Serves as secretary of the safety and health committee
• Coordinates all safety and health programs for the employer and employees
• Conducts safety and health inspections as member of the SH committee
• Conducts investigation of accident as member of the SH Committee
• Maintains or help in the maintenance of efficient accident record system

Advantages of Having the Supervisor as the Accident Investigator

• More familiar with the people involved.
• Have a better understanding of the process or operation.
• Know all safe work practices/rules pertaining to his/her job
• Employees may be willing to speak more freely.

Investigation is a 4 Step Process

1. Control the Scene

 • Provide medical care for injured

        > First Aid

        > On Scene Evaluation

        > Transport for Medical Care

• Control existing hazards

        > Prevent further injuries

        > Get more help if needed

• Preserve evidence

        > Barricade the area of the accident, and keep everyone out!

        > The only persons allowed inside the barricade should be rescuers, law enforcers, and investigators

        > Protect the evidence until investigation is complete

2. Gather Data 

            Ask “What Happened”

• Get a brief overview of the situation from witnesses and victims.

• Not a detailed report yet, just enough to understand the basics of what happened.

            The Interview

• Put the person at ease.

– People may be reluctant to discuss the incident, particularly if they think someone will get in trouble

• Reassure them that this is a fact-finding process only.

– Remind them that these facts will be used to prevent a recurrence of the incident

• Interview as soon as possible after the incident

– Do not interrupt medical care to interview

• Interview each person separately

• Do not allow witnesses to confer prior to interview

• Take Notes!

• Ask open-ended questions

– “What did you see?”

– “What happened?”

• Do not make suggestions

• If the person is stumbling over a word or concept, do not help them out

• Use closed-ended questions later to gain more detail.

– After the person has provided their explanation, these type of questions can be used to clarify

– “Where were you standing?”

– “What time did it happen?”

• Don’t ask leading questions

– Bad: “Why was the truck operator driving recklessly?”

– Good: “How was the truck operator driving?”

• If the witness begins to offer reasons, excuses, or explanations, politely decline that knowledge and remind them to stick with the facts

• Summarize what you have been told.

– Correct misunderstandings of the events between you and the witness

• Ask the witness/victim for recommendations to prevent recurrence

– These people will often have the best solutions to the problem

• Get a written, signed statement from the witness

– It is best if the witness writes their own statement; interview notes signed by the witness may be used if the witness refuses to write a statement

           Securing Evidence      

• Examine the accident scene. Look for things that will help you understand what happened:

– Dents, cracks, scrapes, splits, etc. in equipment

– Tire tracks, footprints, etc.

– Spills or leaks

– Scattered or broken parts  

• Diagram the scene

– Use blank paper or graph paper. Mark the location of all pertinent items; equipment, parts, spills, persons, etc.

– Note distances and sizes, pressures and temperatures

– Note direction (mark north on the map)

• Take photographs

– Photograph any items or scenes which may provide an understanding of what happened to anyone who was not there.

– Photograph any items which will not remain, or which will be cleaned up (spills, tire tracks, footprints, etc.)

• Check training records

–Was appropriate training provided?

• Check equipment maintenance records

– Is regular PM or servicing provided?

– Is there a recurring type of failure?

• Check accident records

– Have there been similar accidents or injuries

involving other employees?

3. Analyze Data

• Gather all photos, drawings, interview material and other information collected at the scene.

• Determine a clear picture of what happened

• Formally document sequence of events

Develop the Sequence of Events

It is important that the sequence of events clearly describe what occurred so that someone unfamiliar with an accident is able to “see it happen” as they read. If an event is hard to understand, it may be that the description is too vague or general.

Determine Causes

• Employee actions

> Safe behavior, at-risk behavior

> Not limited to personnel involved with the accident

• Environmental conditions

> Lighting, heat/cold, moisture/humidity, dust, vapors, etc.

• Equipment condition

> Defective/operational, guards, leaks, broken parts, etc.

• Procedures

> Existing (or not), followed (or not), appropriate (or not)

• Training

> Was employee trained - when, by whom, documentation

Find Root Causes

• When you have determined the contributing factors, dig deeper!
> If employee error, what caused that behavior?
> If defective machine, why wasn’t it fixed?
> If poor lighting, why not corrected?
> If no training, why was it?

Make Recommendations

• Determine corrective actions
> Recommendations based on key contributory factors and underlying/root causes
> Select the ones likely to be most effective, most cost beneficial and most acceptable
> Establish time table
> Recommendation(s) must be communicated clearly

4. Prepare A Report

• Accident Report should contain the following:
> Background Information
> Account of the Accident
> Analysis of the Accident and Conclusion
> Recommendations for correcting the problem(s)

Implement and Follow up

• Implement corrective actions as soon as possible
• Monitor implementation of corrective actions as to their effectiveness
• Conduct follow up and review

CONCLUSION

• An ounce of prevention is better than a pound of cure, as the saying goes, but we still can’t discount the importance of that “pound of cure”.
• The only way to prevent the recurrence of an accident/incident is to have an accurate understanding of the event.

“An accident/incident report is not the end of an accident/incident response
and investigation process, it is in fact the start of the corrective process”

Thank you!