Port Phillip Bay: channel deepening risks eco-catastrophe


On October 31, Victorian planning minister Justin Madden released a report that gave the environmental green light for the dredging of Port Phillip Bay. Channel deepening, which is tied to port expansion, is essential according to the Port of Melbourne Corporation (PoMC) because of the bay's shallowness. Opponents argue that the risks are too great and that alternatives exist, but the Labor state government has made it clear that it wants the project to proceed.

The Blue Wedges Coalition, which draws together 65 organisations opposed to the project, is about to take action in the Federal Court as part of a five-year battle to save the bay.

Issues cited by opponents of the channel-deepening include problems of marine safety associated with the project (it has been opposed by a retired harbourmaster and sea pilots); turbidity, which has impacts on plants, marine creatures and humans; toxicity; and economics — no financing plan has been made public and it is not clear who will benefit. How much will the majority of Victorians benefit and how does it stack up against a possible collapse of the recreational fishing industry in Port Phillip Bay?

There are two issues of immense concern. Firstly, about 3 million tonnes of toxic sediments are to be dug up from the Yarra bed. The sediment can't be legally be disposed of in the open ocean and, according to PoMC, it's too costly to dispose of it on land. Instead, the waste is to be dumped back into Port Phillip Bay, a few kilometres offshore from Brighton, Altona and other suburbs. In a clay-walled bund, the sediment will be left uncovered for at least 140 days and finally covered with half a metre of sand. There is an assurance that the bund will be secure for the lifespan of the project — 30 years — beyond that, we are left to guess.

The toxins include heavy metals, pesticides and other organic compounds — some carcinogenic, many bioaccumulative, and all as unwelcome as they are long-lived. Their persistence in the environment is known to extend far beyond 30 years — probably beyond the very existence of the Port of Melbourne. Who will be monitoring their behaviour in those distant times? Disturbingly, dioxins and radionuclides have not even been tested for.

A second concern is the ongoing and uncontrolled damage at the entrance to Port Phillip. In 2005, PoMC seized on the concept of a "trial dredge". The trial never went near the toxic sediments in the Yarra, which flows into the bay, nor was the hydro-hammer, whose modern functioning was going to surpass the rough blasting techniques of old, used. Yet the trial was hailed as a great success by PoMC.

It was not until two years later that the truth began to emerge, at the hearings for the Supplementary Environment Effects Statement (SEES). The amount of rockfall into the canyon area — a world-class dive site — was not 30 cubic metres but 6000m2. Nor was it just the original rocks, rolling around in the fierce cross-currents, that were causing further damage to the fragile sponge gardens and other habitats. Continued and unexpected fracturing of underlying layers of rock, weakened during the trial dredge, have "scoured" the area in parts to a depth of 22m (three metres lower than even the planned fully dredged depths).

Figures presented to the SEES hearings on how long this damage would last ranged from two to 30 years. This damage was despite the trial dredge involving a mere 6% of the total dredging required for the project.

Prevailing currents are likely to sweep a toxic dredge plume about to be unleashed in the north by the project around the eastern beaches from Port Melbourne as far as Ricketts Point, affecting some of Melbourne's prized inner-city beaches, which are visited by more than 400,000 people annually. While mud might be visible, toxic chemicals bonded to minute particles are not. These toxins could pose a health threat to children playing in the shallows or toddlers who swallow sand.

Ongoing erosion at the south end risks destroying unique habitats. An increase in the volumes of water able to flow in and out through the newly deepened gap may result in changes to currents, tidal patterns, and sediment transportation, as well as other effects. And no amount of modelling will ever be able to predict the impact fully.

Is it any wonder that as the word gradually gets out, there is increasing unrest and anger at what is being perpetrated in this Victorian icon?

[Visit http://www.bluewedges.org for more information. Patsy Crotty is a member of the Blue Wedges Coalition. This article is written in a personal capacity.]

If you like our work, become a supporter

Green Left is a vital social-change project and aims to make all content available online, without paywalls. With no corporate sponsors or advertising, we rely on support and donations from readers like you.

For just $5 per month get the Green Left digital edition in your inbox each week. For $10 per month get the above and the print edition delivered to your door. You can also add a donation to your support by choosing the solidarity option of $20 per month.

Freecall now on 1800 634 206 or follow the support link below to make a secure supporter payment or donation online.