Prosecution Details

Being an employer did not as far as practicable provide and maintain a working environment in which the employees of the employer are not exposed to hazards and by that contravention caused serious injury to an employee.

This charge arose from an incident where a limestone retaining wall and a steel plate collapsed into an excavated trench that was more than 1.5m deep. An employee working in the trench at the time of the collapse was crushed and suffered serious injuries as a result.

Workplace and Employment

The offender, Wormall Civil Pty Ltd, is an Australian Company with ACN 162 970 863. The offender’s main function is to develop land into housing lots. The offender is based in Western Australia.

The offender was engaged to complete the civil works for the proposed housing blocks. This required earthworks to be performed, to create roads and blocks of land that are suitable for houses to be built on. This included the installation of the services such as sewerage, power, and water, as well as installing limestone retaining walls to delineate each block of land.

The offender had direct employees working on site which included:

•    Site Supervisor;

•    Drainer/Utilities Layer;

•    Excavator/Digger Driver;

•    Plant Operator/Loader Driver; and

•    Quality Assessor/Site Clerk/Labourer.

The offender also had managers who would work or visit the site at various times to oversee the works, which included:

•    The Owner/Director;

•    Construction Advisor; and

•    Project Manager.

These three Senior Managers would visit the site at least once every fortnight to speak to the Site Supervisor and do a “site walk around” management meeting.

The offender also had sub-contractors on site at various times. This included a limestone company whose job it was to install the limestone retaining walls.

Work Environment

During the initial stages of civil work, the services such as sewerage pipes are laid prior to any retaining walls being built. This involves excavation works being conducted in order for a drainer to enter the trench and install the sewer Inspection Shaft (“IS”) in accordance with Water Corporation requirements. The IS extends down about 2m in depth.

The Rectification Works

On 24 July 2018, during a site walk around of the Paramount Site, involving the Project Manager, Construction Advisor and Site Supervisor, it was identified that there was a problem with the IS’, as they had not been installed in full compliance with Water Corporation requirements. Specifically, it was determined that each affected IS had been laid too close (500mm) to the road boundary of each lot and further work would be required to enter the excavation and extend the IS so that they were 1500mm in from the road boundary and compliant (“the rectification works”). This needed to occur in six locations or “proposed lots” on the Paramount Site.

The difficulty with the rectification works was that the IS on several of the lots was now located in an open excavation/trench that sat next to adjacent limestone retaining walls which had been substantially constructed and were in the process of being completed.

Relevant Legislation, Internal Policies, and Procedures

Regulation 3.137 of the Occupational Safety and Health Regulations (OSH Regs) defines High-Risk Construction Work as including:

 (g) Construction work involving excavation to a depth of more than 1.5metres;

(p) Work on a construction site where there is movement of powered plant.

Regulation 3.143 requires a Safe Work Method Statement (SWMS) to be completed for High-Risk Construction work.

Regulation 3.111 of the OSH Regs requires an employer to assess the risk and ensure that an area or opening is shored in a manner that will prevent it from collapsing or moving, where:

(a)     any excavating work or earthwork is to be done and there is a risk that the matter forming, or adjacent to, the excavated area or the earthwork may fall or dislodge; or

(b)     a person is required to work in an excavated area or other opening in the ground that is at least 1.5 metres deep.

The Commission for Occupational Safety and Health produced a Code of Practice for Excavation in 2005 (“the Code of Practice”) which was approved pursuant to s57 of the Occupational Safety and Health Act (“the OSH Act”). This Code of Practice provides practical guidance to prevent injuries in workplaces where excavations and associated earthworks are performed. The Code of Practice was not followed by the offender during the rectification works.

The offender had various internal policies and procedures relating to the hazards of working in excavations, but none of these procedures were followed. The internal procedures and relevant documents included:

• The “Project Health, Safety, Environmental and Quality Management Plan for Paramount Site – Stage 1” – Section 16.11 refers to “Excavations and Earthworks” and reads:

“A supervisor must ensure controls are implemented in relation to excavations and earthworks. The Western Australian Code of Practice will be used as the basis of issuing the Permit to Dig for Excavations, where excavations occur to protect personnel from harm from the potential hazards resulting from excavation in the workplace and associated earthworks are performed…All excavations that are >1.5 deep must be shored, battered, shielded or benched in a manner which will prevent it from collapse…”.

• The “Project Risk Register” for the Paramount Site, dated 13 June 2018, specifically refers to managing the hazards of excavation on the project by adherence to the Code of Practice as a control measure (pg. 6). The document also recognises the requirements of the OSH Regulations in relation to safe excavation work.
• The Wormall Civil “Safe Work Method Statement, Paramount Stage one, Sewer Installation” dated 26 July 2018 – Trench Excavation (p. 7) lists control measures for the hazard of trench collapse as “proper trench construction, benching,  battering and shoring boxes as directed”.
• The Paramount Site drawing labelled “Earthworks, Retaining Walls, Standard Details”, dated 5 September 2017, confirms that “no excavation work (is) to be carried out in front of retaining walls without approval from a structural engineer”.

Project Manager Email to Site Supervisor – 6 August 2018

On 6 August 2018, the Site Supervisor and the Project Manager, had a telephone discussion in relation to the rectification works. After that discussion, the Project Manager sent the following email:

“Glenn,

As discussed over the phone due to Dave’s instruction below we will have to extend the IS’s so that they are 1.5m inside the boundary. With the wrap around walls now constructed I cannot see any safe way for a drainer to extend the IS without removing the front boundary retaining wall. We can have a look at it at tomorrow’s meeting but I do not want to see a drainer extending the IS until the wall is removed first”.

Senior Management Site Discussion - 7 August 2018

The following day, on 7 August 2018, there was the usual fortnightly site meeting of Senior Managers at Wormall. This involved a walk-around of the Paramount Site. In attendance at this meeting was: The Owner/Director, the Construction Advisor, the Project Manager and the Site Supervisor.

During the discussion, the group stopped at the first site at which the rectification works would be taking place. The group discussed the hazards involved with excavating close to the adjacent retaining wall. The Site Supervisor proposed to use a steel plate as ad-hoc shoring in an attempt to shore-up the retaining wall.

The group then had a general discussion about this proposal to use a steel plate as shoring in the manner suggested by the Site Supervisor. The Owner/Director gave some general advice to the Site Supervisor about where the excavator truck should be positioned, if the steel plate would be used in front of the retaining wall.

None of The Owner/Director, the Construction Advisor or the Project Manager gave a clear direction to Site Supervisor that he would need to remove the retaining wall in order to eliminate the potential hazard of a worker being crushed by the wall should it be undermined.

The group also failed to give Site Supervisor a clear direction that he was not allowed to use the steel plate as shoring in the unsafe manner he proposed. The use of a steel plate in this manner as “ad-hoc” shoring is not a recognised safe method of shoring in accordance with the Code of Practice.

These types of steel plates are usually used to go on the end of trench boxes, they are not supposed to be used on their own to shore the sides of an excavation close to a retaining wall.

At no point did the group refer to the Code of Practice, or any of the offender’s internal procedures that needed to be followed, prior to the rectification work being commenced.

Incident on 8 August 2018

The next day, on Wednesday 8 August 2018, the usual pre-start meeting occurred at the Paramount Site at approximately 6:45am. Site Supervisor was in charge of leading the pre-start. In attendance at that meeting were: the Victim, the Plant Operator, the Drainer/Utilities Layer and the Excavator/Digger driver and another labourer. Although all of the day’s jobs, particularly High Risk Construction Work, are meant to be discussed at the pre-start meeting, and recorded on the pre-start sheet, there was no mention or record of the rectification works that needed to take place that day.

Following the pre-start meeting, Site Supervisor told the Plant Operator to go to the Brightwood Site and get a large steel plate/sheet (4m x 3m) and take it over to the area of the Paramount Site where the rectification work would take place.

In the area where the excavation work was taking place there was an open trench, with a partially completed limestone wall adjacent to it. The depth from ground level to the bottom of the trench was approximately 1.8m, and the depth of the top of the limestone block wall down to the base of the IS junction that was to be dug out/exposed was approximately 3m.

Prior to the work commencing no Safe Work Method Statement had been developed, the limestone retaining wall had not been removed, and the trench had not been appropriately benched, battered or shored in accordance with the Code of Practice.

Site Supervisor directed the Excavator Driver to set the steel plate up against the side of the trench closest to the retaining wall using the excavator.

At approximately 11:20am the Victim arrived at the trench where the rectification works were taking place and asked Site Supervisor if he needed any help. Glenn told the Victim to go and get a shovel so he could help him dig.

The Victim returned with a shovel and was told by Site Supervisor to get in the trench and help him dig down to find the base of the IS, in order to expose the PVC pipes.

The Excavator Driver was working at the same time, excavating material from the trench using the 30-tonne excavator.  Around 11:30am, Site Supervisor called the Drainer/Utilities Layer over the two-way radio to ask him to come to the trench so that he could start working on extending the PVC pipe.

Site Supervisor gave the Drainer/Utilities Layer a quick brief on what needed to be done to extend the PVC pipe. The Drainer/Utilities Layer then left the work area to get the correct fitting that would be needed to complete the work.

The Drainer/Utilities Layer returned around 15 mins later at which time Site Supervisor and the Victim were in the trench shovelling dirt with the steel plate still positioned against the limestone block wall. The other labourer was also in the trench digging.  

Site Supervisor then then left the rectification works as he was called to another part of the Paramount Site to deal with an issue. The Drainer/Utilities Layer entered the trench and started digging with the Victim and the other labourer.  At that stage, there was no competent supervisor present.

The Drainer/Utilities Layer then got out of the trench and left the area to go to the site office area to find a screwdriver.  The other labourer then exited the trench to talk to the Excavator Driver, this left the Victim as the only person in the excavation.

Around 10 seconds after the other labourer exited the trench, sand, the steel plate and the limestone retaining wall blocks collapsed into the trench. The Victim was pinned by the steel plate and several limestone blocks which weighed approximately 250kg each.

The other workers tried to pull the collapsed material off the Victim, however it was too heavy. The Excavator Driver then used the excavator to remove the material from the victim. He was then lifted out of the trench by his colleagues.

Approximately 30 mins later an ambulance arrived and took the Victim to hospital.

Offender’s Actions Following the Incident

Shortly after the ambulance had taken the Victim away, Site Supervisor told the Drainer/Utilities Layer to get into the trench and finish the job. He also told the Excavator/Digger Driver to use the excavator to remove the limestone blocks and plate from the trench, and get everything tidied up because WorkSafe would be coming.

Between 1.33pm-2.34pm, which was shortly after the incident, emails were sent between senior management personnel at Wormall:

At 1:33pm The Owner/Director sent photos of the accident scene, with the accompanying text:

“Maybe a trench box would’ve been a smarter idea? I had no idea we were going to expose so much bloody wall”

At 1:58pm the Construction Manager replied;

“Trench box would have been a much better idea that is way too deep for a plate to shore up, not a good choice at all. Ambos on site does this mean work safe (sic) could get a call up”

At 2:34pm. The Construction Advisor replies:

“A trench box would have been a better idea, but also Glenn suggested yesterday it was only about 1.2m deep. This looks way deeper than that…

Offender’s Failure to Implement Reasonably Practicable Measures

The rectification work was not mentioned in the daily pre-start meeting on 8 August 2018. Despite the rectification work requiring employees working in an excavation to a depth of over 1.5m, with movement of powered plant nearby, there was no SWMS in place for this High Risk Construction Work prior to the work commencing.  Despite Senior Management identifying during a site meeting the day before that there were obvious hazards involved with excavating in front of a retaining wall, no clear direction was given to the Site Supervisor, that the steel plate should not be used in unsafe manner he proposed. There was also no clear direction given by these Managers that he needed to remove the retaining wall or that the excavation needed to be benched, battered and shored in accordance with the Code of Practice and OSH Regulations prior to any worker entering the trench.

The offender’s own documents confirm any excavation work in front of a retaining wall required consultation with a structural engineer, prior to undertaking the work. Despite this, senior management did not consult a structural engineer.

The retaining wall could have been removed at minimal cost. It would have taken approximately two hours to remove the section of the wall, and the same amount of time to reconstruct it after the work was finished. Removing the wall would have eliminated the hazard.

Trench boxes were available and could have been ordered and used to ensure workers working in the trench were protected from possible trench collapse, or cave-ins. Despite this, no trench box was ordered.

There was also no competent person in charge at all times during the rectification works, at the time of the incident junior workers had been left unsupervised to conduct the High Risk Work.

Serious Harm

Due to being crushed by the retaining wall and a steel plate, the Victim received serious crush injuries to his pelvic region, including multiple fractures to his pelvis and pubic bones and ripped ligaments. He was admitted to the trauma unit on the day of the incident and required surgery two days later to stabilise his pelvis. This included steel plates and screws being inserted. The Victim has been required to undergo physiotherapy, hydrotherapy, and receive support from a psychologist as a result of the incident and his injuries.

The offender was convicted on 10 September 2021.  On 17 September 2021 in the Perth Magistrates Court the Magistrate fined the offender $95,000 and ordered costs of $2044.50.