Eventually, the population of Victoria will double. A third airport will be necessary. The question is when and where?
A third airport is not needed yet. The two existing airports are not nearly operating at full capacity. The third airport should not be at Koo Wee Rup (nor at Tooradin for the same reasons).
There are three main objections to the third airport site at Koo Wee Rup: it is destructive; unduly expensive; and unnecessary.
Koo Wee Rup is the richest soil close to Melbourne for growing the food needed by the expanding population. It should not be neutered, sterilized or destroyed by an airport, its transport systems and associated activities. Once done, it cannot be undone or avoided. It would increase the cost of living and the environmental cost of food brought from further away.
Koo Wee Rup is a swamp. It is well drained, but after prolonged heavy rain it becomes like a saturated sponge. It is difficult to build over. The runway would have to be deeper, stronger and more expensive than usual to withstand all weather safely. The same applies to its facilities.
An airport at Koo Wee Rup is not necessary. The obvious location for the third airport is Sale. The existing military airport should be converted to a military/commercial airport like Canberra and Newcastle Airports. It would be safer, much less expensive and would protect the good soil of Koo Wee Rup for better land use.
Sale Airport in the east would be on the High Speed Rail line to Melbourne and Canberra serving an extra million people in a new city in addition to the 400,000 already now living in Gippsland. HSR would serve commuters from east and west into the CBD at Southern Cross Station. It would connect Tullamarine Airport, Avalon Airport and Sale Airport. It would go on west to Geelong and beyond to a new city of another million people. Eventually, HSR would connect with Adelaide.
The two new cities of 2 million people on the HSR line would relieve Melbourne of the disaster of growing to 8 million and losing its very special, precious liveability.