RAAF Base Richmond is an Royal Australian Air Force base, located within the City of Hawkesbury, and at times, been mooted as a site for Sydney's proposed international what?
RAAF Base Richmond:  Richmond is a regular venue for air shows, and has at times been mooted as a site for Sydney's proposed second international airport. Second Sydney Airport: The Second Sydney Airport is an ongoing proposition for another airport to supplement or replace the existing Kingsford Smith Airport in Sydney, Australia.
Second Sydney Airport