|Defendant||Macmahon Contractors Pty Ltd (ACN 007 611 485)|
|Section||22(1) & 22A(3)|
|Offence Date||3 June 2010|
|Description of Breach(es)||
The Accused, being a person that has, to any extent, control of a workplace where persons who are not employees of that person, work or are likely to be in the course of their work, failed to take such measures as are practicable to ensure that the workplace is such that persons who are at the workplace are not exposed to hazards contrary to section 22(1) of the Occupational Safety and Health Act 1984.
There are three Accused entities that have each entered a plea of guilty to identical charges under section 22(1) and 22A(3) of the Occupational Safety and Health Act 1984 (WA). The facts alleged by the Prosecutor against each Accused is identical.
The Accused entities are:
(a) Brookfield Multiplex Engineering and Infrastructure Pty Ltd (Brookfield) previously known as Brookfield Multiplex Engineering Pty Ltd;
(b) Macmahon Contractors Pty Ltd (Macmahon); and
(c) Zueblin Australia Pty Ltd (Zueblin).
The Accused established an unincorporated joint venture (referred to as the MMZJV) pursuant to a "Joint Venture Agreement for the Alkimos Wastewater Treatment Scheme" dated 13 June 2007.
The Alkimos Wastewater Treatment Scheme (Project) was developed by the Water Corporation and consisted of a number of phases or packages. They were:
(a) the Bulk Excavation of various sites;
(b) the Ocean Outfall works at the Alkimos reef;
(c) the Quinns Main Sewer at Butler; and
(d) the Wastewater Treatment Plant at Carabooda (WWTP).
The Water Corporation selected three partners to form an alliance to deliver the Project. Those three partners were:
(b) Macmahon; and
(c) Zueblin (together with the Water Corporation the Alliance Participants).
The MMZJV was formed for the purpose of delivering the Project. The relationship between the Alliance Participants was governed by an agreement dated 28 June 2007 (Alliance Agreement). Under the Alliance Agreement, the Alliance Participants agreed to design, perform and commission the Project works and to collectively assume and manage and mitigate the risks involved in performing the Project works.
Under the Alliance Agreement, the Alliance Participants:
(a) agreed that safety of Project personnel and the public is of highest priority (clause 1.2(a));
(b) was committed to the collective responsibility for all risks in performing the work (clause 2.2(b));
(c) agreed to satisfy and comply with all statutory requirements contained in the Occupational Safety and Health Act 1984 (WA) (clause 10.2(b)); and
(d) agreed to provide and maintain a working environment where people are not exposed to hazards (clause 10.18(a)).
The incident in this matter occurred in the Project works which formed part of the WWTP.
The WWTP was further broken down into:
(a) Civil works;
(b) Mechanical works; and
(c) Electrical works.
Construction of the Valve Pit
Part of the civil works for the WWTP required the construction of a valve pit shaft between two large sedimentary tanks. At completion, the valve pit shaft would be a cement shaft, lined with a high density polyethylene lining. The shaft would be approximately 2 metres wide and 7.5 metres deep. It would have a ladder down the inside of the shaft to access a valve in the pit at the bottom. The valve would be used to control the flow of water and wastewater between the two large sedimentary tanks and other outputs.
Construction of the valve pit shaft commenced in or around early 2010. The valve pit shaft was constructed from the bottom up by placing reinforced concrete rings which are approximately 3 metres in height, on top of each other to form a shaft. The area where the valve pit shaft was constructed had been excavated out from ground level to around 7 -8 metres below ground level.
As the construction of the WWTP progressed, the ground level around the valve pit shaft was raised up towards the original ground level by backfilling around the valve pit shaft with sand. This happened gradually over months.
By that construction method the valve pit shaft was, during the construction phase, usually around 1 - 1.5 metres above the level of the surrounding sand. In those circumstances, the valve pit shaft acted as a barrier that prevented persons from falling into the shaft.
In or around early May 2010, the final concrete ring was placed on the valve pit shaft. The shaft, at that stage, was approximately 7.5 metres deep and 2 metres wide. The sand around the valve pit shaft was backfilled to a point that the valve pit shaft extended out above the sand to about chest height. Whilst at this height two semi-circle pieces of fibreglass reinforced plastic mesh (Grid Mesh) were placed on top of the valve pit shaft to prevent rubbish from being thrown down the shaft.
On or about 13 May 2010 and after the final concrete ring had been placed on the valve pit shaft, the Site Superintendent for the Project (who was employed by Brookfield), instructed the Earthworks Supervisor for the Project (who was employed by Macmahon), to further backfill around the valve pit shaft (final back fill).
Following the final back fill, the concrete ring that formed the top of the valve pit shaft was approximately 200 mm above the level of the ground and the plastic liner inside the concrete ring extended approximately 100 mm higher above the concrete ring. The top of the plastic liner was, in total, approximately 300 mm above the ground.
Following the final back fill, the valve pit shaft no longer acted as a barrier that prevented persons from falling down the shaft.
Installation of various components
Once the valve pit shaft had been constructed, components such as the permanent lid, the internal ladder, the valve and valve connections were to be added. These various components formed part of the mechanical and electrical works.
The majority of the mechanical and electrical works was contracted out by the MMZJV, primarily, to Downer EDI Engineering Pty Ltd (Downer) under a written contract dated 17 December 2009 (installation contract). Under the installation contract, Downer was to procure and install the permanent lid for the valve pit shaft.
At the time of the final back fill, the permanent lid for the valve pit shaft had not yet been procured or installed by Downer.
On 1 June 2010 the area around the valve pit shaft was handed over by the MMZJV to Downer to enable it to undertake certain works under the installation contract.
On and from 1 June 2010 to 3 June 2010 personnel from Downer were working around the valve pit shaft. The work being undertaken by Downer included the digging of trenches to enable conduit to be laid. One of these trenches was close to the valve pit shaft and sand dug from this trench was piled next to the valve pit shaft.
The Grid Mesh
A potential fall down the valve pit shaft at the Workplace was a hazard (the Hazard).
Prior to the final backfill when the top of the valve pit shaft was at approximately chest height, the Earthworks Supervisor, was told to place the Grid Mesh on top of the valve pit shaft.
It is not clear who instructed the Earthworks Supervisor to place the Grid Mesh on top of the valve pit shaft.
The Earthworks Supervisor in turn instructed an employee of Macmahon, and a JSP Fencing contractor to place the Grid Mesh on top of the valve pit shaft, which they did.
The Grid Mesh was comprised of two halves (two semicircular pieces) split down the centre of the overall circular shape. Each semi-circular piece weighed approximately 30kgs.
The Grid Mesh sat on top of the plastic lining that extended approximately 100mm above the final concrete pipe that formed the top of the valve pit shaft. It was not secured or fixed to the valve pit shaft in any way.
The Grid Mesh was not designed to be used as a lid for the valve pit.
The Grid Mesh was available on site because it had been used inside several horizontal pipes and drains to prevent debris and rubbish being thrown into the pipes and drains, or in some cases to prevent persons from entering into the pipes when there were no workers on site.
The Permanent Lid
Under the installation contract Downer was to supply and install the permanent lid for the valve pit shaft as detailed in drawing JS25-010-023.
The lid specified in drawing JS25-010-023 was to be a Webforge aluminium webplate and was designed with six locking points to be locked with Water Corporation padlocks.
Drawing JS25-010-023 required the dimensions of the lid to be site checked by Downer.
A Site Manager /Project Manager, employed by Downer, stated that the dimensions of the lid were not obtained until the valve pit shaft had reached its final height.
Therefore, at the time that the valve pit shaft reached its final height, the lid had not been ordered or fabricated and was unavailable to be installed on to the valve pit shaft after the final back fill.
The Instruction to the Victim
On 3 June 2010, a surveyor employed by RM Surveys Pty Ltd trading as RM Surveys (RM Surveys), and a surveyor's assistant also employed by RM Surveys, were requested to obtain survey data for the valve pit shaft.
That request was made by a Site Engineer employed by Brookfield.
The Incident on 3 June 2010
On 3 June 2010, the surveyor's assistant went about surveying the valve pit shaft with the surveyor. The surveyor's assistant was responsible for holding the prism pole in place, whilst the surveyor recorded surveying data on the theodolite which had been set up approximately 10 metres away from the valve pit shaft.
In the course of performing the surveying, the surveyor's assistant walked to the valve pit shaft located between Secondary Sedimentation Tank 1 and Secondary
Sedimentation Tank 2 to position the prism pole he was holding over the valve pit shaft to enable Armstrong to obtain survey data.
At approximately 1:15pm on 3 June 2010, the surveyor's assistant stepped on to one semicircular half of the Grid Mesh on top of the valve pit shaft with his left foot. As he raised his right foot off the sand, the Grid Mesh gave way and he fell approximately 7.5 metres to the bottom of the valve pit shaft.
The valve pit shaft was not marked with any warning signs to prevent or deter persons from standing on the Grid Mesh. The valve pit shaft was not barricaded to prevent or deter persons from standing on the Grid Mesh and was not fenced off to prevent or deter persons from standing on the Grid Mesh. The Grid Mesh was not secured to the valve pit shaft. The two semi-circle halves of the Grid Mesh were not secured together.
The Grid Mesh wasn't marked in any way to suggest that it shouldn't be stood on.
As a result of the fall, the surveyor's assistant suffered injuries including a collapsed lung, laceration to the spleen, laceration to the liver and split pancreas. He was taken by helicopter to Royal Perth Hospital where he underwent emergency major trauma surgery. He remained in Royal Perth Hospital until 12 June 2010 (10 days). He returned to work following the incident.
After the incident, wooden boards were placed on top of and fixed to the valve pit shaft. Further, a hard barricade was put up around the valve pit shaft.
The Accused failed to take such measures as are practicable to not expose persons to the Hazard.
It was practicable for the Accused to have done one or more of the following:
(a) covered the valve pit shaft with a temporary lid which would mitigate or eliminate the surveyor's assistant's exposure to the Hazard; alternatively
(b) placed edge protection around the valve pit shaft to mitigate or eliminate the surveyor's assistant's exposure to the Hazard; alternatively
(c) fixed boards over the top of the valve pit shaft to mitigate or eliminate the surveyor's assistant's exposure to the Hazard; alternatively
(d) secured the Grid Mesh in a way that mitigated or eliminated the surveyor's assistant's exposure to the Hazard.
The Accused failed to take any of the practicable measures referred to in the above paragraph hereof.
The Accused entered a plea of guilty and was convicted.
|Conviction Date||07 Jun 2013|
|Court||Magistrates Court of Western Australia - Joondalup|