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Project Summary - Perrin Creek Realignment
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Client |
Port of Brisbane Corporation |
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Location |
Riverside Place, Colmslie |
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Contractual Completion Date |
November 2009 |
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Original Contract Value |
$1.9M |
Port of Brisbane Corporation awarded the contract to McIlwain Civil for the diversion of Perrin Creek in July 2009 as part of their strategy for the redevelopment of their industrial site at Colmslie. The works included the diversion of the existing creek under flow and tidal influences as well as the backfilling of a section of the existing creek to maximize the development potential of the site. The new section of creek was lined with gabion mattresses and included the connection of existing stormwater outlets to the new alignment.
Working within a live waterway presented a number of challenges for the project team. These challenges were overcome by using a purpose designed weir box to block tidal flows during the initial stages of construction which allowed quick removal of the blockage in the case of a major rainfall event. Once the initial stages were completed the diversion of the creek meant that the channel could no longer be blocked and all works had to be completed under tidal and run off influences. The water level ranged from approximately 800-2000mm above the base level of the new channel. This required state of the art GPS control earthworks machinery to ensure design profiles were achieved. The installation of gabion mattresses in these areas required prefabrication, lifting with a 150t crawler crane and placement with a specialist crew equipped with appropriate dive gear.
All excavated material was contaminated with Acid Sulfate Soils and therefore had to be removed from site, transported to Fisherman Islands and dumped under water in designated reclamation areas within 48 hours of exposure. Any material unsuitable to be taken to Fisherman Islands was heavily treated with lime, tested for validation and removed from site to an approved landfill facility. All exposed surfaces and stockpiles were also treated with lime to avoid contamination of any surface water.
The project was completed in early November approximately three weeks prior to the contractual date of practical completion with no safety or environmental incidents. This was achieved through effective project and construction management as well as a collaborative approach between Port of Brisbane Corporation and McIlwain Civil in the resolution of any construction issues. McIlwain Civil continues to be considered by Port of Brisbane Corporation as a preferred Civil Contractor for any port related infrastructure works.
PROJECT SYNOPSIS
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