The Melbourne Cricket Ground comes in handy when describing big things - it is a particular quirk of the Victorian vernacular. Hugeness is instantly conveyed: enough people to fill the MCG, enough water, waste or empty beer cans.
And so it is with the Port Phillip Bay channel-deepening project. It has been said, and no one remembers now by whom, that the sand and sediment the Port of Melbourne Corporation wants to scour from the bay's bottom will be enough to twice fill the MCG to the top of the Great Southern Stand, if it went all the way around.
Someone else has said the spoil from deepening Melbourne's shipping channel would fill Nauru House up to 40 times. The actual amount, for the record, is 30 million cubic metres for the deepening, and another 10 million to maintain the channel over the next 30 years. "It is a vast amount," says John Arup, the consultant in charge of the Port of Melbourne's $12.5 million environmental effects statement.
The project is a widely misunderstood venture that has failed to register with most lovers and residents of Port Phillip Bay: four people showed up to a "stakeholder-specific meeting" in Rosebud last Saturday, and seven turned up for a similar St Kilda meeting on Wednesday. But the stakes are high for both the bay and the Victorian economy. Allowing bigger ships into the bay, says industry, would mean more jobs and lower freight costs, therefore cheaper exports and imports for consumers.
On the flipside, the environmental risks include everything from potential harm to St Kilda's penguin colony, destruction of the marine environment at the heads, and the finely balanced water quality of the bay itself.
Melbourne is Australia's biggest container port, but it has one big problem: its shipping channel is shallow. The monster ships that crawl up the bay and into the docks are gradually becoming the minnows of the international shipping fleet - outpaced by deeper, wider and generally bigger agents of global trade.
Already this affects businesses that rely on the port, through which 82 per cent of Victoria's imports and exports are moved. In the past six months, 32 per cent of ships came in with less than 80 per cent capacity. If the ships were fuller and, therefore, heavier, they would hit the sea bed.
The big ships get rid of some of their load before hitting Melbourne, says Rose Elphick, the acting head of the Victorian Sea Freight Industry Council. They may drop off containers (some with perishable goods) in Singapore or at another Australian port and the extra cost of getting the goods to their destination is paid by the importer or exporter, and eventually the consumer. If this situation continues, Elphick and the Victorian Employers Chamber of Commerce and Industry say, Melbourne will gradually lose business and jobs to more competitive, deep-water ports such as Brisbane. In a $400 million project, the Port of Melbourne wants to deepen the channel in four places so that ships with 14-metre draughts can get into the bay. Elphick says the efficiencies of fully laden ships could mean a saving of $30 to $40 for each container of goods.
University of Melbourne professor of economics John Freebairn says deepening the channel will be a cost-effective way of lowering freight costs. But the environmental costs must be factored in, he says. "You and I have to make a decision: do we want to find it more expensive to export and import and leave the bay untouched, or are we going to lower the cost of freight and accept the potential changes to the environmental services offered to us by Port Phillip Bay?"
So far, the big-ticket environmental concern has been the fear that more water will come into the bay, causing flooding and beach erosion. This fear stems from the bay's particular geography. The bay's mouth between Point Lonsdale and Point Nepean is a narrow gate that controls the flow of water from Bass Strait. Once ocean water gets through the heads, it stays around for about a year.
The Port of Melbourne plans to widen the heads, removing 400,000 cubic metres of rock. The port says the affected area will be small, but the idea of widening the heads and possibly lifting the bay's water level has environmentalist Len Warfe almost beside himself.
"Any increase in water level will cause more coastal erosion and flooding in low-lying areas; there's no doubt about that," says the Dromana resident and senior vice-president of the Port Phillip Conservation Council Inc. "Combined with the accepted greenhouse sea level rise, there's no way you should be artificially increasing the sea level to let bigger ships in."
The potential impact on bay levels is being studied by oceanographer Dr David Provis, who has 16 years' experience of the bay's hydrology and is one of around 50 specialists working on the environmental effects statement. The first thing he wants bayside dwellers to know is that their lounge rooms will not be flooded. In fact, his modelling shows the project will have "no impact on coastal processes".
Having said that, his computer models reveal a slight impact on the bay's tides. Looking at tides over one month, 1 per cent will be more than eight millimetres higher but all will be less than one centimetre.
His modelling on the bay's sea level found no extra areas would be wetted and no change in the frequency of inundation of any piece of coastline. Other modelling revealed that any change to the heads would have no impact on storm surges. The bay's wave patterns would be unaffected.
Scientific experts who know the bay say their biggest worry is the bay's unique and delicate ecosystem, which controls its water quality. In 1992, Melbourne Water commissioned the CSIRO to do a $12-million, four-year study of the bay, the biggest ever. One of its findings was that the bay's water quality was actually very good. Bugs and animals on its floor process nutrients and keep the bay from turning into an algal soup.
The study recommended that any disturbance to the bay's bottom be minimised. "The science was categorical on that," said the man who led the study, CSIRO research fellow Graham Harris. "The ecology at the bottom of the bay preserves the values that the community cares about."
The key risk is not the deepening of the channel itself, but the disposal of the spoil. A small amount of the 40 million cubic metres may go to building an environmental island or beach restoration but most of it will be dumped on the bay floor across an area of 1497 hectares.
"The placement of material would smother anything that is there," says consultant John Arup, the EES manager. This includes the aforementioned bugs. It could have a food-chain domino effect that affects everything from dolphins to fish to penguins.
Another environmental storm is brewing at the heads. Rock must be removed at the top of beautiful canyons which Peter Fear, the owner of Dive Victoria, says are just as ecologically important as nearby marine parks.
Arup says the main environmental concern is rock falling into the canyons. The Port of Melbourne is looking at using a dredger that breaks and then sucks the rock up. But the dredging operation is particularly difficult because of the strong currents and dynamic activity at the heads.
The other concern is that explosives may be needed, and this could affect the nearby marine ecology as well as fish, seals, dolphins and penguins.
The deepening of the south part of the channel - which runs parallel to Portsea through to McCrae - also has potential environmental and tourism impacts. This area is important for fish larvae, birds, sea grasses and shallow reefs. It also has some very fine sand that, when dredged (by a ship that sucks it up from the bottom) may suspend itself in the water column and create a plume, says Arup.
Arup says the dredging technique must be improved because the risk is that a plume will smother important sea grasses and reefs, reduce sunlight and impact on the biodiversity. Maintenance dredging created a large milky plume last summer - to the outrage of divers, fishers and dolphin tour operators.
In this same area, off the coast from Rosebud and Blairgowrie, the Port of Melbourne has floated the idea of building an environmental island. The island would take a few million cubic metres of the spoil and hopefully create a habitat for birds.
The island is looking like a wobbly idea because the EES experts admit it will be difficult to make the sand stay where it is. The last thing they want is it washing back into the channel.
Moving further north, there is the logistical concern of having to relocate one of the city's main sewer lines, but the main environmental risk is the contamination of the spoil near the Yarra.
Tests have shown that the sediments are polluted with industry, agriculture and storm water chemicals, including arsenic, lead and zinc. The key concerns, says Arup, are the impacts of putting this onto another area, and that it may contain marine pests.
Len Warfe questions whether the deepening is necessary at all. The Port Phillip Conservation Council believes Melbourne should instead rely on rail for freight (an idea dismissed as uneconomical and slow by John Freebairn).
The Port of Melbourne has just released its Key Features report, which outlines the environmental issues. The project's communications manager, Lisa Faldon, said in March-April next year the port would release another report that would outline how it proposed to deepen the channel in "a way that is environmentally responsible".