No airport is going to be built anywhere in Sydney's western suburbs that won't generate a huge nimby reaction, particularly in regards to noise. The locals will love the better roads and railways that go in to support the new airport - and developers will throw up closely packed MacMansions by the squadillion as close to the boundaries of the new airport as they can while it is being built (or in Richmond's case, extended),
... and then the people who'll buy said MacMansions will scream blue bloody murder about the aircraft noise, and because they vote, they'll be heard.
And the new airport will have a curfew and silly bloody 'noise sharing' rules before it's even fully operational.
Fact.
As I said above, Botany Bay would make a lot more sense and end up cheaper in the long run.
....if it wasn't for that rare as bat**** Botany Bay three-toed sulphur crested peri-newt.