“Shallow trenches can be dangerous too.” When it comes to excavations, temporary support equipment can be critical to help secure and shore up the ground, ensuring the safety of those working on site. However, there can still be the misconception that such support equipment is not needed in shallow trenches, despite safety still being a key concern. Here, Heath McHugh, our Head of SHEQ, explores the importance of temporary support equipment in shallow trenches and the features to look out for…
As an industry, and even just generally speaking, we all know the dangers of working at height. In fact, from the 79% of all fatal workplace injuries that were accounted for between 2017 and 2022, falling from a height was the most common cause. But what about working below ground?
For many years, the Construction (Working Places) Regulations 1966 had specified that only a trench or excavation which exceeded a depth of 1.2 metres should have a shoring system in place. However, these regulations were revoked in 1996, deemed to be too specific and restrictive. Today, Regulation 22 of CDM 2015 deals specifically with excavations; yet makes no reference to depth. Instead, it requires those in control of the work to prevent danger to any person from the collapse of an excavation or dislodging of material. More specifically, “suitable and sufficient steps must be taken to prevent any person, work equipment, or any accumulation of material from falling into any excavation; while there must be a safe means of getting in and out of the excavation appropriate to the type of excavation, the work being carried out, and the risks associated.”
While it can be easy to look at a shallow trench and assume that no support is needed, it’s important to remember that no ground can be relied upon to safely stand unsupported in all circumstances – regardless of the excavation size. This is further reinforced by the fact that even just a cubic metre of soil can weigh as much as 1.5 tonnes. With this in mind, it becomes clear that potentially serious accidents can happen even in trenches of shallow depths, whether caused by the collapse of free-flowing ground, sand or gravel injuring people working in them, material falling from the sides into any excavation, or people and plant equipment falling into the trench.
Ultimately, the law states that you must prevent danger to any workers who are either in or near an excavation, regardless of its size.
Carrying out shallow trench excavations can be a common occurrence for contractors, especially those working within the utility sector, required to access and repair water pipelines or install new connections, for example. While one method of achieving shallow trench support can be to batter back the trench sides, which involves cutting away the sides at a set angle to reduce the risk of collapse, this is definitely not a ‘one-size-fits-all’ approach. It is heavily dependent on the site location and ground conditions. For example, while it may be possible in an unrestricted rural setting, if you’re working within the constraints of a built-up residential area, you likely won’t have the flexibility to extend the working area on each side.
It is here that working with a temporary works specialist, one that possesses a wide range of ground support equipment to suit a variety of trench sizes and ground conditions, can be invaluable. When it comes to shallow shoring and selecting the right piece of equipment for the job, there are various factors to consider and look out for.
Flexibility
It goes without saying that trenches can vary significantly from job to job, both in terms of the ground conditions on site but also what you find in the trench, such as existing electric, gas or telecommunication services. As such, it’s helpful if your chosen temporary support equipment can be easily adapted to suit the on-site conditions. For example, some trench boxes have the ability to add or remove panels, allowing existing services to pass through.
Modular
As has been shown above, trenches and their support requirements can differ from site to site and job to job. In order to always be prepared and ready to adapt to the on-site conditions, modular trench boxes can be ideal, with the ability to easily convert the equipment from a 2-sided trench box to a 4-sided.
Lightweight
Whether you’re working in a rural setting or city-centre location, access can often be a challenge – especially when it comes to coordinating heavy plant equipment. By choosing shoring equipment that is lightweight and easy to handle you can reduce this challenge, with the ability to install the trench box or sheets either by hand or with a small excavator. Not only this but some lightweight solutions can be installed from the safety of ground level, meaning that workers are not required to enter an un-supported trench in order to assemble.
Lightweight equipment also makes transportation and storage easier too, an important consideration if it’s a small team.
Standard solutions
In the case of reactive or emergency trench support jobs, such as those involving a burst water main, a fast response can be critical. In order to meet this need for speed, making use of a temporary works provider’s ‘standard solutions’ can be ideal. Making its experience and expertise readily available, a temporary works provider may offer a series of pre-approved engineered designs for shallow trench support projects, ready for easy ordering.
It is clear that shallow trenches can be just as dangerous as deeper excavations, making it essential for teams to use appropriate temporary support equipment to secure the ground, ensuring the safety of those working on site. When choosing temporary support equipment for shallow trenches, it is important to look for equipment that is quick and easy to install, suitable for the ground and trench conditions, and properly maintained and inspected. By taking these precautions, we can ensure that all excavations, even those in shallow ground, are carried out safely and without incident.
