Element 11 - Excavation Work & Confined Spaces Flashcards
What are the hazards associated with excavation work?
- Buried Services
- People Falling In
- Objects and Materials Falling In
- Collapse of Sides
- Collapse of Adjacent Structures
- Water Ingress
- Use of Cofferdams and Caissons
- Contaminated Ground
- Toxic and Asphyxiating Atmospheres
- Mechanical Hazards
What are the factors to consider when conducting a Risk Assessment for Excavations?
- Depth of Excavation
- Soil Type (Non-cohesive, Cohesive, Rock)
- Type of Work (side of a road, in a housing development, laying pipes/cables, trenches, pits)
- Use of mechanical equipment (types being used)
- Proximity of the excavation to roadways, watercourses. structures, schools, hospitals
- Presence of the public/children
- Weather
In relation to Buried Services, what action should be taken before work is carried out?
- Check any available plans
- Contact local services providers and owners (electric, gas, water, TV)
- Survey the site and surrounding area to identify indicators of the existence of cables (streetlights, junction boxes)
- Use cable locators/detectors with trained operators
Identify some safe digging methods/procedures?
- Using locators to determine position and route of cables/pipes
- Look for evidence of pipes/cables….plastic pipes will not be detected by locator
- If contact is made with pipes/cables, STOP work until it is safe to proceed
- Regard all buried cables as LIVE until disconnection is proven. Pot-ended cables cannot be assumed as dead/disused
- Excavators and power tools tools should not be used within 0.5m of the indicated line of a cable or pipe
- Hand digging should be employed when nearing a cable/pipe
- Spades/shovels should have curved edges and used rather than forks/picks
- Report damage to appropriate services…keep personnel clear until it is repaired
- Have an emergency plan to deal with damaged pipes/cables
- Exposed cables/pipes should be supported/protected against damage by back-filling. Don’t use as foot/hand holds
List the types of excavation support?
- Battering
- Shoring
- Trench Boxes
What factors determine which excavation support is used?
- Type of ground being excavated
- Length of time excavation will be open and in use
- Type of work being carried out
- Groundwater conditions and potential for flooding
- Depth of excavation
- Number of people in excavation
List some General precautions associated with Excavations?
- Identify buried services
- Support sides
- Provide suitable access/egress
- Provide crossing points
- Barriers, lights and signs used to demarcate danger areas
- Remove spoil and store at safe distance
- De-watering and freezing methods used to remove water
- Vehicles and material kept away from sides
- Provide workers with suitable/appropriate PPE
What are the particular requirements for excavating Contaminated Ground?
- Soil testing
- Additional/specific welfare facilities
- Health Surveillance
When are inspections required for excavations?
- At the start of each shift
- After any event likely to have affected the strength or stability of the excavation (e.g. flooding)
- After any material unintentionally falls or is dislodged
Explain the criteria associated with an Inspection Report of an excavation?
- The report must be completed before the end of the shift in which the excavation was inspected
- A copy of the report must be given to the person in charge of the worksite within 24 hours of the inspection
- Reports must be retained at the site until the excavation work is completed and thereafter for 3 months
- Only 1 written report is needed every 7 days, unless the strength or stability of the excavation is affected.
What must an excavation report contain?
- Date, time, location and a description of workplace inspected
- Name and position of person inspecting/making the report
- Name of the person on whose behalf the inspection was carried out (i.e. person in charge of worksite)
- Details of anything identified as a HSE risk, and actions taken to control them
- Details of any further actions considered necessary
What is the definition of a Confined Space?
It is any enclosed space where there is a reasonably foreseeable specified risk of injury associated with it
Give examples of Confined spaces?
Trenches, Sewers, Manholes, Chambers, Pits, Tanks, Vats, Silos, Reaction Vessels, Flues, Ductwork
What are the “Specified Risks” associated with Confined Spaces?
- Serious Injury arising from Fire or Explosion
- Loss of consciousness arising from an increase in body temperature
- Loss of consciousness arising from asphyxiation due to gas, fume, vapour or lack of oxygen
- Drowning arising from a free-flowing solid (e.g. flour, grain, sand)
- The inability to reach a respirable environment due to entrapment by a free-flowing solid
What are the key duties associated with the Confined Spaces Regulations 1997?
- Avoid entry where possible (e.g. do the work from the outside)
- If entering then follow a safe system of work and put in place adequate emergency arrangements before work starts