1. Risk of Working with Trenches and Excavations
Source : USACEpublicaffairs
A serious issue in the world of construction is the danger presented by trench and excavation
work. It is important for workers to be trained and adequately informed regarding safety work in
and around trenches and excavations.
Once the hazards on a site have been identified (for example hazards presented by
trenches/excavations) the risks associated with these hazards needs to be assessed. Once the
risks have been assessed they can be eliminated and replaced with a safer work method or
plans can be designed to minimise the harm they can potentially cause.
In order for employers to meet their legal requirement they need to provide workers with a safe
system of work. This involves ensuring that workers are not unexpectedly exposed to any
hazards and that they receive the necessary training, information and supervision to operate
safely on a construction site.
Even before beginning trench and excavation work, the person responsible for the site should
obtain as much information as they can relating to the site’s ground conditions.
Once the ground’s condition has been identified employers need to decide on the system of
ground support they will use. They will also need to consider weather conditions as well as the
proximity of in-ground services.
The basic requirement is that a risk assessment be conducted and the appropriate control
measures be put in place. An engineer will need to be used to assess excavations of more than
1.5 meters in depth. The engineer’s report can then be used to design control measures to
There are a plethora of factors that determine the stability or instability of trenches or
excavations. Some of these factors include adjacent buildings, spoil pile, ground vibration and
weather conditions (especially rain).
2. Another important aspect of trench and excavation work that is often ignored is that trenches
need to be examined daily to ensure that it is still safe for workers to operate in. This inspection
should include surveillance of trench walls, support systems and excavations.
Remember the following when working with trenches:
Avoid solitary work because of the possibility of collapse. It is simply not safe to work
alone in a trench or excavation. If the trench should collapse or an accident should
happen you may only be found much later when it is too late to get help or medical
Ensure that adequate personal protective equipment be utilised correctly. Workers
should have received training on the relevant PPE because if not used correctly, their
effectiveness is jeopardised. The risk assessment stage of construction safety should
determine which PPE are to be utilised.
Ensure the appropriate signage to warn workers not involved with trench work of the
Erect the proper barricades to keep workers separated from the hazard as much as
Most importantly never try to gain entry into a confined space unless you are trained to
do so because these spaces present a unique hazard that can be deadly if you are not
sure what you are up against.
Tunnels, shafts and trenches should have entry and exit openings that are large enough
for a properly equipped person to pass through without danger of it collapsing. The size
and number of openings also have an impact on the ventilation which needs to be kept
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