Element 4

Question 1

What are the “specified risks” found in a confined space?

Answer 1

• Increase in body temperature
• Loss of consciousness (gas, vapour, fume, lack of oxygen)
• Drowning
• Asphyxiation due to free-flowing solids

Question 2

What are the types of soil that need to be carefully examined to ensure excavation sides are stable and perhaps need support?

Answer 2

• Saturated (clay) silts
• Saturated silt or sand
• Sand
• Soft clays
• Rock

Question 3

What are the types of support measures that can be used to prevent excavation sides from collapsing?

Answer 3

• Battered sides
• Benched sides
• Double sided support (hydraulic struts and walings)
• Single sided with raking support
• Steel trench sheeting
• Trench boxes
• Drag boxes

Question 4

What is the definition of a confined space?

Answer 4

“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”.

Question 5

What are the main hazards associated with excavation work?

Answer 5

• 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

Question 6

What are the main hazards associated with working within a confined space?

Answer 6

• Exposure to toxic, explosive, and oxygen-deficient atmospheres
• Heat
• Water
• Free-flowing solids
• Restricted space

Question 7

What other controls should be considered to prevent workers and others falling into excavations?

Answer 7

• Access into excavation
• Crossing points
• Barriers and edge protection
• Lighting and warning signs
• Vehicle stop blocks

Question 8

What are the precautions to be considered in a safe system of work (SSOW) for confined space working?

Answer 8

• 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

Question 9

What are the typical confined spaces found during construction work?

Answer 9

• Trenches
• Sewers
• Chambers
• Tanks
• Pits
• Cellars
• Manholes
• Excavations
• Cofferdams, Caissons
• Tunnels