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Safety during Excavation work on a construction site

Excavation:

Excavation are man made cut,cavity,trench or depression in the earth surface formed by the earth removal

Hazards:

  • Cave In
  • Collapse of sides.
  • Fall of a persons.
  • Material or vehicles into the excavation.
  • Weakening of adjacent structures.
  • Contact with buried services or contaminated soil.
  • Build of fumes.
  • Ingress of water and contact with mechanical plant.
  • Electrical Hazard,Buried live cables
  • Presence of Toxic Gas.


Protective systems include:
  • Sloping. This means the sides of the hole open out from the excavation. The type of soil determines the required angle.
  • Benching. This system is similar to sloping with steps cut into the sides of the trench. (Note: A registered engineer must approve sloping and benching systems in excavations more than 20 feet deep.)
  • Shoring. This supports the walls of the excavation. Shoring is made up of wales, cross-braces and uprights, and must be installed from the top down and removed from the bottom up.
  • Shielding. Shielding involves trench boxes or trench shields that are placed in the excavation to prevent the sides of a trench from caving in. The worker is only protected while in the “box.” Some boxes can be moved throughout the work process. The shield must extend at least 18 inches from the top of the slope of the trench.
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Control measures:

  • A competent person must evaluate possible dangers before work begins and until the operation is completed.
  • The operation must be monitored at all times.
  • Protective systems must be used for any trench or excavation that is 5 feet or more deep. (Excavations that are less than 5 feet deep also may require a protective system if the competent person onsite thinks a cave-in is possible.)
  • Authorized Gas test should test the atmospheric condition.
  • Excavated soil should keep 5 m away from the edge.
  • Shoring, benching etc (support of sides).
  • Detection of services (e.g. from plans, use of cable /pipe detectors etc).
  • Storage of materials, equipment and spoil away from edge.
  • Means of preventing vehicles falling into the excavation or causing collapse (i.e. stop, blocks).
  • Means of preventing peoples falling in (guard rails, barriers, crossing points and covers).
  • Means of preventing collapse of adjacent structures.
  • Safe means of access & egress.
  • Testing for, and ventilation of, noxious fumes.
  • Pumping out water facility.
  • Procedures for working with mechanical plant.


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