Whether you believe that channel deepening is good for the Victorian economy or not, do you still think it’s a reasonable thing to dump three million tonnes of toxic sludge in the bay? Neil Blake believes this crucial question should be asked of all Victorian politicians. He is the coordinator of the Port Phillip EcoCentre, a resource and support for community groups undertaking environment initiatives in the coastal area of Melbourne.
Neil Blake has worked in the northern area of Port Phillip Bay for twenty years; for some of that time as a park ranger. Since the mid 1980s he has also been involved in the study of the St Kilda penguin colony. ‘There are major issues for the southern bay too, but there are local naturalists down there who are much better placed to comment on them than I am,’ he says.
Neil Blake outside Victorian State Parliament |
The channel deepening project in Port Phillip Bay involves dredging the mouth of the Yarra River and the entrance to the bay, known as the Heads, to allow ships with fourteen metre draughts access to the ports of Melbourne. The Port of Melbourne Corporation believes a world-wide trend to larger container ships makes the project necessary for the more than 18 000 jobs dependant on the port. According to Tim Holding, the Victorian Minister for Manufacturing and Export, the port supports 80 000 jobs (The Age)
A total of forty million cubic metres (40 000 000 tonnes) will be dredged over two years of continuous works. This includes mud and silts from the Yarra River and silty sands from Hobsons bay. Sand and rock from Port Phillip Heads will be removed by intense hydro-hammering. The dredged materials will be disposed of in the bay.
Public submissions on the project were received in August last year. This was followed by a Planning Panel hearings process which concluded in December. The panel overseeing the process submitted a report to the Victorian planning minister, Rob Hulls, on 11 February this year but the findings are yet to be made available to the public.
If it goes ahead, the area at the mouth of the Yarra will be dredged between one and a half and two and a half metres deeper than ever before. This will stir up mud where contaminants have been settling for the past 150 years. These include mercury used in early gold mining in the upper Yarra catchment, and a host of toxicants from the highly industrialised parts of western Melbourne. Electroplating industries, for example, are a likely source of cadmium, lead, chromium, copper, and zinc. As Neil Blake points out: ‘Until the mid 1980s it was still legal for factories to dump their chemical effluents into the storm water system.’
The toxins will only be adding to other problems. The giant vacuum cleaner sucking up the mud from the river bed will inevitably cause currents that stir up finer particles. ‘This is where turbidity kicks in – it’s much murkier,’ says Blake. ‘You can talk about the brown Yarra, but it still allows sunlight to penetrate to enable the microscopic plants to grow on the bed of the river. The additional particles stirred up by the dredge will block sunlight from getting through to allow plants to photosynthesize and grow. Ordinarily, these plants are the start of the food chain. What food the fish can find is likely to be toxic. It’s hitting them from all directions and the proposal is to do this for two years in a row.’
He also can’t understand why the project is scheduled for the spring/summer period. ‘Anyone who takes time to observe local conditions at the top end of the bay would know that we get our heavy rainfall in spring and summer – real torrential downpours. The heavy rains flush all the nutrient-laden crap from the urban catchment – all manner of animal excreta, leaf litter and garden fertilizers, into the river at once. It fires up the system. The nutrients being washed into the river kick start the food chain.’ In spring and summer there are more hours of sunlight and therefore more photosynthesis. ‘More photosynthesis means more algae to provide forage for bugs who provide food for fish,’ Blake says.
However, dredging releases nutrients that were previously trapped within the mud. Combining these with nutrients flushed from the catchment can overload the system. The burgeoning algae blooms will create oxygen during the day but when they die the process of decay uses more oxygen than is being produced. Oxygen depletion especially occurs during the night when photosynthesis shuts down. ‘The system is demanding more oxygen than is actually being supplied so you get things dying and releasing more nutrient into the system as they decay. It’s a spiraling down sort of effect. A general dieback of organisms leaves the system less capable of assimilating nutrients and ultimately reduces biodiversity.’ Blake says. Concerns about this were raised by the CSIRO in the mid 1990s and it was recommended then that dredging in the bay be kept to a minimum.
Neil Blake has a number of concerns with the Channel Deepening Environment Effects Study (EES). ‘There should have been separate Environment Effects Studies for each geographical area affected. There is wide variance of characteristics between the north and south of the bay and to attempt to address all areas in the one process has caused confusion,’ he says. He cites the methodology used for modelling of turbidity and sediment transport as an example of this confusion. ‘The model designed for this study used a constant salinity level for all areas. This is not representative of the waters around the mouth of the Yarra where freshwater enters the bay and salinity can vary markedly. Particles remain suspended for longer periods in waters with lower salinity. Once remobilized by the dredge they will remain in the water column longer than predicted in the EES Study,’ Blake says.
He considers another major deficiency of the report to be the lack of an overall picture of what happens in the bay. ‘It had about sixteen different consultants actually doing specific studies but the overlap and reference to each other is limited,’ Blake says. ‘So it’s also hard to respond to the report in a tangible way.’ He sees this as symptomatic of a broader malaise. ‘A national freight handling strategy, properly costed according to triple bottom line outcomes, is needed before we start building freeways through any bay. The logical thing to me is for the bickering between the states to be taken out of the equation. What we really need to see is some national leadership from the federal government and logically it should be based around where there are achievable infrastructural developments,’ he says. ‘With appropriate expenditure on rail infrastructure to move goods rapidly to and from other parts of the country perhaps existing deepwater ports are the logical choice.’
If the federal government does decide to engage in a bit of nation building, they had better be quick. New Matilda was told that the proposed start date for the project is March, this year – now. This is despite the fact that the ships with the larger draughts won’t be commonly used here for another ten years and even then, they will be in the minority. Why the rush? Why are we risking the disruption of the food chain in the bay for two years? How long will it take for fish stocks to recover? And why is it a reasonable thing to dump three million tonnes of toxic sludge in the bay?
‘Channel Deepening Issues in Northern Port Phillip Bay’, a paper by Neil Blake, is attached here as a PDF file: Paper
The Blue Wedges coalition is a ‘grass roots’ association formed in response to the Victorian State Government’s proposed deepening of the shipping channels in Port Phillip Bay, The Rip and Yarra River: www.bluewedges.org
The EcoCentre is a not-for-profit, community-managed environment group supported by the City of Port Phillip. The EcoCentre provides a base for fifteen affiliate groups involved in a range of activities that promote bio diversity and community action: www.ecocentre.com
The Port of Melbourne Corporation: www.portofmelbourne.com/portdev/channeldeep/index.asp
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