We're just slightly off the Camden Valley way (but further down in Elderslie) and its not a bush fire prone area or in a flood zone so it may pay to check a few lots if you have a choice - I think most lots sell quickly.
With respect to Badgery's creek mentioned earlier on - I was previously in Dulwich Hill, approx 7ks from the airport and was within a flight path for 10 years and never really thought that the noise was bad and we didn't have any noise insulation etc, we are currently in Surry Hills which again is around 8k from the airport and see planes but can't hear them. I must say though that both these areas tend to catch planes that are taking off and somehow the noise seems to be less. Whenever I'm in Leichhardt faced with planes coming in to land they do seem closer and much noisier. Distances mentioned above are by what google tracks by road - in a direct line they are closer.
I know a lot people see the second airport as an unpopular decision but from someone that has lived close to an airport for many years I really don't see it as anything to fear. Although there can be plenty of poor planning and it's likely to be very tight on roads and public transport in the short term, in the long run a second airport closeby (but not too close) will be a good thing and drive a lot of industry/employment and highlight the need for better surrounding infrastructure that should realistically follow.