Wikipedia says: Cordeaux Airfield (Landing Ground), Cordeaux Dam, New South Wales, during WW2
Cordeaux Airfield was constructed in late 1942 near Cordeaux Dam in New South Wales as an RAAF landing ground (maintenance) for its parent RAAF airfield at Albion Park.
The airfield consisted of a sealed runway 5,000 feet long and 150 feet wide running NE/SE with twelve aircraft hideouts. Original Works were authorised to build the sealed runway and 24 hideouts. Remnants of the airfield can still be seen today where it crosses Mount Keira Road about 5.6kms north of Cordeaux Dam.
Here's a close-up showing the current terrain (a "fire road") with the original runway and hides as an overlay. I'd bet there's some decent archaeology to be found scattered around those hides.
I made the composite images from Google Maps and OzAtWar sources. Thanks go to both. OzAtWar also has another location map to check out.
Here is an updated list of Sydney's airports.