Posted on 1 January 2011
To extend and deepen the port of Melbourne, Boskalis signed a risk-sharing alliance contract with the Port of Melbourne Corporation in 2004. As the port is situated in a bay with a rich biodiversity one of the most rigorous environmental dredging plans in the world was developed. A lot of energy also went into supplying information to all the stakeholders. Furthermore, Boskalis developed innovative equipment needed for the project. The project was successfully completed ahead of schedule in 2009.
To make the port of Melbourne accessible to 14m draught container vessels during all tidal phases, in order to maintain its position as number one container and general cargo port in Australia. And do this within the limits of the environmental parameters set in the Environmental Management Plan. Scope included dredging the entrance, deepen the shipping channels and remove and deposit contaminated silt and protect the existing pipelines in the bay.
- Assisting with the Environmental Management Plan
- Dredging the entrance channel
- Removal and deposit of contaminated silt
- Protecting operational pipelines
- Execute project according to EMP
Stakeholder acceptance of the project was closely related to the accurate and transparent communications made by the Alliance Team. These included public consultations, a dedicated website, a 24-hour toll-free telephone number, weekly press conferences, media releases, mailing lists, signage around the Bay and notices to mariners.
- A trailing suction hopper dredger was deployed to pump 1.4 million m³ of contaminated silt through a 750m-long pipeline and a special developed diffuser to an underwater disposal area. This was enclosed by a bund of clay 5 meters high and 40 meters wide, and eventually capped with a layer of clean sand;
- A special frame was developed for the protection of existing, operational pipelines by positioning steel plates over them with great precision and within the stated tolerances;
- A unique ‘ripper’ draghead was developed for use on a trailing suction hopper dredger in order to dredge the entrance to the bay and remove around 460,000 m3 of limestone. This allowed us to combine the maneuverability of a hopper with the strength of a cutter;
- The remaining loose material was regularly suctioned off to prevent the strong currents from carrying it to the nearby nature area.
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