Category 1 Finalist
CCF EARTH AWARDS – Excellence in Civil Construction
McCallum Park Causeway Underpass and Stormwater Drainage Upgrade
The wall of the McCallum Park Causeway Underpass is technically a sea wall, and the walking surface of the underpass is over 1 metre below sea level. The tidal movement penetrates the underpass and causes major flooding, which has been a safety hazard to the users over several years.
MMM’s scope of works included:
• Decommission, demolish, remove, and dispose of existing pumping infrastructure, limestone river wall, surface treatments (including pavements) and surplus subsurface
- Dewatering as required in accordance with discharge requirements and conditions by relevant authorities
- Supply, install and grade reinforced concrete, including base slab, walls, kerbs, joints, seals, and sealed pre-cast sumps
- Supply and install two new submersible pumps, including associated civil, mechanical, electrical and control systems
- Supply and install surface cut-off drains and outlets.
For the limestone retaining wall, the design engineer provided a generic drawing of a limestone retaining wall not suitable as a sea wall. Relying on MMM’s experience in constructing seawalls around the Swan River for many years (including the South Perth Promenade for which it won a 2015 Earth Award), the engineer permitted MMM to construct a suitable wall for the required application.
The Causeway Bridge Underpass is located within the environmentally sensitive Swan River habitat. Meticulous management was required to ensure that environmental impact was minimised. Works cannot be carried out within these areas managed by the Department of Parks and Wildlife without the client applying for a permit first, detailing the work methodology and any potential implications on the habitat.
DPAW’s permit was subject to specific terms and conditions, including approval of a detailed Construction & Environmental Management Plan. This was approved with one query on the dewatering. As below-ground dewatering can increase the complexity of the work and can also alter groundwater levels – which could result in the acidification of waters and soil horizons if not managed appropriately – MMM proposed to surface pump the tidal water to a constructed infiltration pond on the park. This was approved by DPAW and the works commenced.
The works were completed three days ahead of time and on budget. Town of Victoria Park Asset Manager Gregor Wilson said: “MMM WA Pty Ltd has proven themselves to have the ability to deliver this technically complex drainage project, with numerous site constraints. The work has been to the required quality and integrity, while maintaining budget and time imposed restraints. They were collaborative and easy to work with. They took ownership and responsibility for the project and understood the project and its objectives.”