VRCA investigations show a global trend in shipping to increasingly larger vessels to achieve economies of scale. The authority and the Port Phillip Sea Pilots, who carefully guide ships into the Port of Geelong, know even small increases in a ship's dimensions can have serious ramifications when navigating Corio Bay's narrow channels. The multi-million dollar improvements are a key to providing safe, efficient passage for the next generation of longer and wider ships to the busy port.
The Geelong Dredging Project 2015, funded by the VRCA, involves:
- Dredging adjacent to Refinery Pier No 4 berth. About 240,000 cubic metres of silts, silty clays and stiff clay will be removed from the area between Lascelles Wharf and Refinery Pier to aid the safe navigation of ships.
NZ-based Heron Construction Company will carry out the dredging work. Heron will use its backhoe dredger Machiavelli to excavate the material from the seabed 24 hours a day during the program, which will take up to 8 weeks to complete. Two split-hopper barges, manoeuvred by tugs, will transport the dredged material to an approved dredge material ground in Port Phillip Bay about six kilometres east of Point Wilson.
This dredge material ground has been used for previous projects, including the major capital dredging works in the Geelong channel network in 1997, and the Geelong Dredging Program 2014.
Drysdale-based Elstone Diving Services has the specialist task of removing an existing navigation beacon which will no longer be required when dredging is completed. Elstone will also place temporary floating buoys to aid navigation as required and recover the buoys when the work is done.
Dredging is a routine part of maintaining and improving Geelong's shipping channels. It has occurred periodically during the past 150 years and is an important activity in ensuring the Port of Geelong and its channel network can operate at capacity now and in the future.
While the Machiavelli is in Geelong, the VRCA will conduct a trial dredge of basalt rock at the eastern end of the Wilson Spit Channel.
While most of the sea bed material underlying the channels is relatively soft, there is a hard basalt outcrop intersecting the eastern end of the Wilson Spit Channel. This basalt was encountered during the last major channel deepening contract in 1997.
Any future significant widening or deepening proposal for the existing channels will require the removal of a significant volume of the basalt. The current proposal therefore is to use the Machiavelli fitted with a rock ripping head, to assess whether the basalt can be effectively removed by this method.
A successful trial dredge would provide the VRCA with valuable information on the likely methods to be adopted for future channel improvement works, and hence assist in the planning of such improvements.
The scale of the proposed trial is small compared with the current GDP 2015 works, and the duration of the trial is not expected to exceed two weeks, with completion by mid-November.
Geelong's shipping hub and the companies reliant on it generate billions of dollars for the region each year and provide jobs for more than 7000 people. It's an important gateway to the rest of the world for Victoria's wide-ranging businesses, and it helps keep the state's economic heart beating strongly.
The Geelong Dredging Project 2015 and the Rock Trial Dredge are governed by an approved Environmental Management Plan and dredging contractors must follow a strict set of rules that ensure the protection of Corio Bay's marine environment. Monitoring after the 1997 major capital dredging project, which removed 20 times the volume of material earmarked for the current work, and recent dredging experience has revealed no long-term health effect on the bay's marine environment.
The dredging schedule will not impact on commercial ships or the port's daily operations, but recreational bay users must observe a 150-metre exclusion zone around major dredging equipment as part of a raft of strict safety rules.
The VRCA acknowledges people have a genuine interest in Corio Bay. The authority set up a community group to discuss its dredging plans several months ago and will continue to consult with members and port stakeholders as work progresses.