In October 2018, two workers in an excavation were injured when a 1350mm diameter concrete stormwater pipe toppled over. They were installing a short 500mm length of the large diameter pipe by abutting the pipe up to the end of a recently laid pipe and using timber and sandbags as chocks to support the pipe in position. It appears one of the workers may have moved a sandbag and the pipe toppled over. One worker was trapped beneath the pipe for several minutes and his leg was broken. Investigations are continuing.
Preventing a similar incident
Excavation work introduces a number of risks that must be managed, including the risk of people working in the excavation being crushed by unrestrained or inadequately restrained pipes. In addition, weather conditions such as rain or wind can affect ground conditions and cause objects to become unstable.
Control measures to prevent unrestrained or inadequately restrained objects in the excavation from toppling over include:
- temporarily securing or restraining concrete pipes or other objects to prevent them from moving and toppling over during installation, particularly short pipes that have a large diameter and relatively small area on the supporting surface (i.e. ground or chocks). This could mean tying the object back to other stable elements of the installation or bracing the object from suitably designed footings
- ensuring the ground surface, packers and chocks are suitable for supporting the pipes or objects being laid until final works and backfilling is completed
- using suitable lifting attachments, such as C hooks, which will support shortened pipe sections until suitable bracing or restraint can be securely attached to the pipe to prevent unintended movement
- where possible, designing the stormwater system connections to avoid installing short concrete pipes, particularly pipes of a large diameter
- ensuring workers have adequate knowledge and training to perform the task safely (for example, young, new or inexperienced workers may be unfamiliar with a task)
- monitoring and supervising the workers who are required to be in the installation area and ensuring any exclusion zones are enforced
- ensuring there are adequate procedures for all potential emergency situations.
Since 1 July 2012, there have been 208 notified events involving workers or bystanders being injured, or at serious risk of being injured, in excavations and trenches. Of these, 10 involved workers or bystanders being injured, or at serious risk of being injured, by a falling object in excavations or trenches.
In the same period, 240 improvement notices, 175 prohibition notices and three infringement notices have been issued for workers or bystanders either being injured, or at serious risk of being injured, from excavations and trenches.
Each year there are over 70 accepted workers' compensation claims involving a worker injured in a pit or trench. Of these claims, almost half involve a serious injury requiring five or more days off work.
Prosecutions and compliance
In 2017, a company was fined $40,000 after a 15 year old first year apprentice plumber's leg was fractured when a large piece of concrete, weighing approximately 400kg, fell from the side of a trench. He was clearing soil from around underground power cables to expose them before further digging by an excavator. The cables were approximately 500mm below the surface and he was instructed to finish the job using hand tools to remove the remaining soil. The work was near to an open trench that was approximately 2.6 metres deep and 2 metres wide with unstable and unsupported sides. He had finished clearing soil from around the cables and moved back toward and into the larger trench to move away from an approaching excavator. As he moved into the larger trench, the concrete fell from the side of the trench onto his leg.
- How to manage work health and safety risks code of practice 2021 (PDF, 0.65 MB)
- Managing risks of plant in the workplace code of practice 2021 (PDF, 1.57 MB)
- Excavation work code of practice 2021 (PDF, 1.9 MB)