Shoring Boxes and Trench Support Systems Alert Issued


Workplace Health and Safety Queensland has released a safety alert to highlight the risk of trench collapse when trench support systems such as shoring boxes don’t extend for the full length of the trench.

The alert comes after a November incident involving ground collapse at a trench on a Brisbane construction site. A worker was seriously injured during the accident.

A similar incident occurred in 2016 at a Gold Coast construction site.

In both incidents the shoring boxes did not extend for the full depth of the trench in both incidents.

The alert highlighted that a variety of factors can contribute to such a collapse including the type of ground, ground water, rain and loading applied to the ground.

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Construction Worker Partially Buried during Accident on Site

A Michigan construction accident stemming from work in a trench almost claimed the life of a 40 year old man recently. The man was fortunate to escape death when the walls of a trench he was working in collapsed, trapping him waist deep in the hole. The man was lucky to be rescued by co-workers and only sustained injuries to his legs and pelvis and some internal injuries as well.

The following excerpt explains what happened during the incident:

A 40-year-old Hudsonville man was hospitalized Thursday after a construction accident partially buried him.

Brian Segard was part of an excavating crew building a new portion of a road at Jasper Drive and Zion Drive in Georgetown Township when the walls of the 8-foot deep trench collapsed, trapping him from the waist down, according to the Ottawa County Sheriff’s Office.

He was freed by other workers on the scene and taken to Spectrum Health in Grand Rapids in stable condition with injuries to his legs and pelvis as well as internal injuries.

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Although ensuring trench safety is a lengthy process from inception to completion of the work, there are a few basic tips that workers should keep in mind when engaging in trench work.

Firstly each worker must be authorized to work in the trench before entering and workers should never enter an unprotected trench, even if instructed to do so because this is endangering their life.

Each employee in a trench should be protected from a cave-in by an adequate protective system. Some of the protective systems for trenches are ensuring they are sloped for stability or cut to create stepped benched grades. Another system is using posts, beams, shores or planking and hydraulic jacks for support of the trench. Some trenches may be supported by a trench box to protect workers in a trench.

Additionally, excavated or other materials must be at least 2 feet back from the edge of a trench ideally to prevent it falling in and causing the edges of the trench to collapse.

The 4 basic steps of Trench safety include:

  1. Have a properly trained and competent person on site. In addition to each worker being adequately trained, a competent person should be present on site to regularly inspect trenches for any signs of potential collapse, hazardous atmospheres and other hazards. This person should be able to identify any existing or foreseeable hazards which may threaten the safety of workers in or around the trench area.
  2. Secondly it is important that the general WH&S requirements are followed. All Australian standards relating to trench work need to be adhered to. This includes addressing issues such as fall protection, vehicular traffic risks, hazardous atmospheres, stability of the adjacent structures etc.
  3. The soil should be carefully and thoroughly analysed by a competent person beforehand. Analyzing the soil is the first step to choosing the appropriate Protective System.
  4. Utilize a Protective System, for example shoring or benching, this is extremely important to prevent collapses and cave-ins.


Trench Safety in Construction

Trench Rescue

(Source : Charlotte Fire Department Charlotte NC)

Quite often we hear of workers being trapped or injured while engaging in trench work. The biggest risk involved in trench work is that of the trench collapsing.

Working in wet conditions is one of the biggest causes of trench instability because as the ground becomes more moist it also becomes less stable. Poor stability combined with the work processes involved with construction such as use of heavy machinery can be a recipe for disaster.

Before engaging in trench work these risks should be taken into account. Workers should never engage in trench work unless supervised or in the presence of a co-worker who can raise the alarm if something goes wrong.

It is also important that work is planned in a manner that it can be safely conducted, including engulfment protection and site security requirements.

A safe work method statement (SWMS) must be designed for work involving mobile plant or trenches more than 1.5m in depth.

Building materials, plant and machinery should be kept away from the edge of the trench.

While more often than not the weather is the cause of trench accidents, human error can also be the cause which is why attention to the issue is so vital to worker safety.


White Card Update: Trench Safety Warning

WorkSafe has warned that construction workers need to be aware of the danger of working around trenches. Construction workers in particularly are in danger of being injured when trench walls collapse. This warning follows an incident which saw a plumber sustaining serious injuries after a trench collapsed where he was working. Thankfully the worker did not suffer any serious injuries because as WorkSafe warns, the situation could have been much worse. This alert posted on WorkSafe’s website has more:

WorkSafe is reminding the construction industry of the dangers associated with trenches after one collapsed on a worker at a domestic housing site at Pakenham at the weekend.  The incident happened a week before a 12-month statewideWorkSafe campaign targeting safety on housing construction sites. Injuries on construction sites cost the industry $17 million a year in medical costs, wages and other expenses. The trench collapsed on a plumber while he was connecting a sewer at a housing construction site about 9.30am on Saturday. WorkSafe’s Construction Manager Allan Beacom said it was fortunate the worker had a colleague nearby who was able to raise the alarm. “Broken limbs, asphyxia and crush injuries are just some of the serious injuries that can occur when a trench collapses,” he said. “This man is incredibly lucky he wasn’t seriously injured; the consequences could have been a lot worse.” Mr Beacom said the incident was a reminder to the construction industry to review safety practices. “Unfortunately, this is not the first time we’ve come across an incident where a trench has collapsed on a worker. This time last year, WorkSafe issued a safety alert on this topic as we were coming across a number of incidents being engulfed in collapsed trenches.” “There’s a range of control measures that can be implemented before beginning work on trenches. They are well-known across the industry and should be implemented to eliminate any risk of a collapse.” “As we’re in the middle of winter, it’s equally important that environmental factors such as wet weather conditions and increased ground moisture are taken into account as they could affect soil stability.” “Poor soil stability and loose earth places workers at greater risk of serious injury if a trench is a metre or more deep. We urge those who are putting together a safe work method statement to take these factors into account.” Other control measures include ensuring:   –    A colleague is on site while trench works are being carried out; 1.Work is planned so it can be done safely, including determining appropriate; engulfment protection and site security requirements; 2.A safe work method statement (SWMS) is developed for high risk work that involves mobile plant or if the trench depth is 1.5m or more; 3.Workers never work outside of protection shields or remove it prematurely if it is being progressively installed; 4.Materials, spoil and plant are kept away from the edge of the trench. The Code of Practice for Safety Precautions in Trenching Operations can be found at Source:

A similar incident occurred last week when a worker was trapped waist deep in a trench and had to be rescued by emergency services. The accident happened when the man was working in the trench at a new housing project in Pakenham. The bad weather in the area caused the trench to collapse, trapping the worker in the hole. Emergency personnel had to use specialist equipment to free the man. This included the use of hydraulic equipment that firefighters utilised to dig the trench safely and prevent further collapse. The worker was been taken to hospital and thankfully only suffered minor injuries. The good news is that the authorities say these types of incidents are isolated which means that most workers do the right thing and work safely. The weather was the cause of the incident and not human error. This worker was lucky to escape unscathed however planning, developing safe work method statements and general caution when working near trenches will ensure that incidents of this nature remain uncommon.