What a complex subject! A possible solution would have been to buy up all the land around it, up to the edge of the noise complaints...
In terms of Aircraft noise, I see the biggest difference in having an established noise generator vs a new development. In terms of Lismore, we have substantially less noise than in the 80's and 90's, but the sensitivity to noise has substantially increased, especially by new member of the community who were never exposed to previous levels. All you have to do it look at what happened in the 2017 floods...new business owners in the CBD did not take it serious and post flood suffered the biggest losses.
The Public Health act is definitely something to consider though. If there is already a move against high amenity noise (can be very subjective, as Turboplanner pointed out), then ANY noise generating infrastructure is under thread.
I do agree that sometimes there is ways of mitigating issues, but in my experience with engineering, it's always a compromise. In the case of noise (being subjective) I fear that the compromise will not be logical and shared....God, I have turned into a cynic!