Construction activities – hazards and control
Hazards associated with excavations
There are about seven deaths each year due to work in excavations. Many types of soil, such as clays, are self-supporting but others, such as sands and gravel, are not. Many excavations collapse without any warning resulting in death or serious injury. Many such accidents occur in shallow workings. It is important to note that, although most of these accidents affect workers, members of the public can also be injured.
The specific hazards associated with excavations are as follows:
• collapse of the sides
• materials falling on workers in the excavation
• falls of people and/or vehicles into the excavation
• workers being struck by plant
• specialist equipment such as pneumatic drills
• hazardous substances particularly near the site of current or former industrial processes
• influx of ground or surface water and entrapment in silt or mud
• proximity of stored materials, waste materials or plant
• proximity of adjacent buildings or structures and their stability
• contact with underground services
• access and egress to the excavation
• fumes, lack of oxygen and other health hazards (such as Weil’s disease).
Figure 14.8 Timbered excavation with ladder access and supported services (guard removed on one side for clarity). Source HSE. Crown copyright material is reproduced with the permission of the Controller of HMSO and the Queen’s Printer for Scotland.
Clearly, alongside these specific hazards, more general hazards, such as manual hand¬ling, electricity, noise and vibrations, will also be present.