You may have made a submission to the Sydney Gateway project last year to the NSW government process. There is one more chance, to the Commonwealth Major Development Plan (MDP) process (as this project involves Federal land), which closes tomorrow (midnight 21 Feb)
Submissions on the preliminary draft MDP should be in writing to sydneygateway@syd.com.au and must include your name and address.
What to say:
The Sydney Gateway proposal does not have any cycleway or footpath connection to the domestic terminal and so is inconsistent with the Sydney Airport Master Plan 2039 and the Five Year Ground Transport Plan 2019-2024 which have objectives of reducing car dependence and increasing active travel. It should not be approved until an active transport link between the Alexandra Canal and the domestic terminal is included.