Element 11: Excavation

Question 1

What are hazards associated with work in & around excavation?

Answer 1

• Buried Services
• Falls of persons/ equipment/ material.
• Collapse of sides
• Water ingress
• Use of Cofferdams & Caissons
• Contaminated ground
• Toxic & asphyxiating atmospheres
• Mechanical Hazards

Question 2

What factors taken into account RA for excavations?

Answer 2

• Depth
• Soil type
• Type of work
• Use of mechanical equipment
• Proximity of roadways/ structures
• Presence of public
• Weather

Question 3

What controls may be necessary during excavation work?

Answer 3

• Identifying & marking buried services. Safe digging methods
• Methods of supporting excavation (steel sheets, support boxes)
• Safe means of access
• Safe crossing points
•Barriers
• Lighting & warning signs
• Safe storage of spoil
• De watering
• Positioning routing of vehicles plant & equipment.
• PPE
• Additional controls contaminated ground- separate welfare facilities

Question 4

What particular hazards may arise during excavation of contaminated ground?

Answer 4

• Uncover buried materials or contaminants hazardous to health.
• Contaminants change over time due to bacterial or chemical action, may alter properties. May be result of decomposition organic matter or dumping or spillage hazardous substances.
• Some contaminants specific legislation Asbestos, lead, anthrax, radioactive material & explosives well established procedures followed.
• Radioactive hazard’s possibly from previous occupation
• Toxic & asphyxiating atmosphere
- flammable gases, methane, carbon monoxide plant machinery used.
- Hydrogen sulphide
- Chemicals & metal compounds on container or within soil

Question 5

What inspection requirements for excavations?

Answer 5

No person allowed until examined by competent person. inspected at start of each shift & after any event may affect strength stability- flooding accidental fall of rock or other material.
Report made & records kept of inspections.

Question 6

What is definition confined space?
Where found on site?

Answer 6

Enclosed space with foreseeable risk of serious injury associated with it
• Trenches
• Sewers
• Manholes
• Tunnels
• Excavations
• Chambers
• Tanks
• Pits
• Cellars
• Cofferdams @ Caissons

Question 7

What precautions necessary safe entry into confined space?

Answer 7

• Avoidance where possible
• Safe Access Egress
• Permit to work procedures & Implemented
• Atmospheric testing
• Risk Assessment
• Training
• Use of competent persons
• PPE.

Question 8

Factors involved in SSOW confined space entry?

Answer 8

• Adequate competent supervision
• Experienced & competent workers
• Proper Isolation of plant & equipment
• Pre cleaning & correct disposal of sludge & debris
• Adequate lighting & ventilation
• Atmospheric testing
• Provision of specialist non sparking tools
• Emergency arrangements/ plans

Question 9

Hazards Associated with confined spaces.

Answer 9

• Heat
• Water
• Solids free flowing
• Restricted space.
• Toxic, explosive oxygen deficient atmosphere