Ventia's Barangaroo project team has been recognised for Merit in Site Safety by the Master Builders Association of NSW at the Excellence in Construction Awards 2020.
The team's approach to safe remediation of the old Millers Point Gasworks, was acknowledged by the association, in particular our efforts in leading by example to ensure continued reputation for excellence in keeping our people and those around us safe in the course of our works.
The old Millers Point Gasworks operated from the mid 1800's to the early 1920's. When the Gasworks was decommissioned in the 1920's, above ground structures were removed, but many structures were left below ground. The land was eventually concreted over in the 1960's to provide storage for shipping containers, but no remediation work had occurred, leaving around 450,000 tonnes of contaminated material below the surface.
Project challenges
One of the key challenges facing the team when approaching the remediation task on this project, was how to safely demobilise an enormous odour control enclosure (OCE) on an excavated site. Traditionally this demobilisation would occur after the site has been backfilled, however the scope of this project required a different approach.
The OCE was a required part of this project to ensure that the works do not impact the local environment and community.
To cover the site, the OCE itself needed to take up a footprint of 22,500m2 (slightly bigger than the Melbourne Cricket Ground) and with the excavated ground, would reach heights of 29 metres in some areas.
Early on, the team identified multiple safety risks associated with working at this height and lifting operations using the traditional methods of OCE demobilisation. Therefore, an innovative design was required to mitigate these risks.
Pictured above: aerial view of the odour control enclosures (OCE).
Taking an 'end-in-mind' approach, the demobilisation of the OCE became the focus of design of the OCE structure itself. Using 3D modelling of the work the team were able to conceptualise a solution which mitigated a number of the major risks. The industry-first solution combined smart engineering, clever design and a safety-first approach.
What emerged was an innovative rolling OCE structure, with the segments designed to roll on caster wheels, guided by rails. This design enabled individual segments to be moved to a safe area where it could be safely disassembled in the traditional way. The benefits of this rolling design not only mitigated a number of high-risk activities but also reduced the size of plant required for the works. For example, instead of using a 500 tonne crane and 125 foot elevated work platform (EWP), the works were performed using a 150 tonne crane, a small 25 tonne Franna crane and three 50 foot EWPs. The smaller plant items were able to perform well within their safe working limits.