What are the “specified risks” found in a confined space?
- Increase in body temperature
- Loss of consciousness (gas, vapour, fume, lack of oxygen)
- Drowning
- Asphyxiation due to free-flowing solids
What are the types of soil that need to be carefully examined to ensure excavation sides are stable and perhaps need support?
- Saturated (clay) silts
- Saturated silt or sand
- Sand
- Soft clays
- Rock
What are the types of support measures that can be used to prevent excavation sides from collapsing?
- Battered sides
- Benched sides
- Double sided support (hydraulic struts and walings)
- Single sided with raking support
- Steel trench sheeting
- Trench boxes
- Drag boxes
What is the definition of a confined space?
“Any place, including any chamber, tank, vat, silo, pit, trench, pipe, sewer, flue, well or other similar space in which, by virtue of its enclosed nature, there arises a reasonably foreseeable specified risk”.
What are the main hazards associated with excavation work?
- Buried services
- Fall of person, equipment, or material into the excavation
- Collapse of the sides
- Collapse of adjacent structures
- Water ingress
- Contaminated ground
- Toxic or asphyxiating atmospheres
- Use of cofferdams and caissons
- Mechanical hazards
What are the main hazards associated with working within a confined space?
- Exposure to toxic, explosive, and oxygen-deficient atmospheres
- Heat
- Water
- Free-flowing solids
- Restricted space
What other controls should be considered to prevent workers and others falling into excavations?
- Access into excavation
- Crossing points
- Barriers and edge protection
- Lighting and warning signs
- Vehicle stop blocks
What are the precautions to be considered in a safe system of work (SSOW) for confined space working?
- Appointment of supervisor
- Isolation
- Cleaning and ventilation
- Suitability and competence of workers
- Adequacy of access and egress
- Provision of suitable tools and lighting
- Gas testing of atmosphere
- Relevant PPE and RPE
- Permit to work as necessary
- Emergency rescue plan in place
What are the typical confined spaces found during construction work?
- Trenches
- Sewers
- Chambers
- Tanks
- Pits
- Cellars
- Manholes
- Excavations
- Cofferdams, Caissons
- Tunnels
