Explosives ruled out for deepening Port Phillip

Explosives has been all but ruled out as the means of deepening the Port Phillip bay channel into the Port of Melbourne.

In a strategies brochure or environmental effects statement published by the Port, it says modern dredging methods would enable shaving of the channel floors to allow fully laden ships into and out of Australia's busiest port.

To allow vessels drawing 14m into Port Phillip – the current allowable maximum is 12.1m at high tide – dredgers would have to remove an estimated 32.7 million m 3. Two thirds of that would come from the south channel immediately inside the heads.

The EES decided the best options for disposal of the dredged material were to:

Create an island off Rosebud;

Create a marine habitat to the south west of Capel Sound, between Blairgowrie and Rosebud; and

Utilise the remaining capacity and a southern extension of the existing dredge material grounds and develop a new DMG in the north of the Bay as well as other DMGs.

A variety of dredging methods will be needed.

For the heads a trailer suction hopper dredge with a specially fitted drag head to mechanically remove the rock would be the most appropriate.

The drag head in effect rips the rock which is sucked up it into the “trailer” of the dredge.

In the Yarra river, a backhoe dredge may be used to trim the channel sides and a sweep barge may be used to level the seabed during and after dredging.

The 22 page EES is particularly careful to lay out all the possible environmental concerns.

“Of particular concern are the slow growing sponge gardens growing on the walls of the canyon at the Heads,” the EES says.

Further information: Sandra Williamson, Port of Melbourne Corporation, 03 9628 7555, sandra.williamson@portofmelbourne.com

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Explosives ruled out for deepening Port Phillip

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