The oldest independent girls' school in Australia is in a battle with local councils, residents and NSW Police over its $63 million expansion plans for a 500-seater "world-class auditorium", aquatic centre, research facility and multi-purpose hall.

St Catherine's School, in Sydney's eastern suburbs, is seeking to increase its student numbers by 25 per cent in its submission to the NSW Department of Planning and Environment.

The development includes a swimming pool, shallow pool, water polo and diving facilities, as well as an orchestral pit and a fly tower for state-of-the-art theatre productions where 120 events are expected to be hosted each year.

Data from the MySchool website reveals that the Waverley school has already breached its student cap by more than 20 students, generating an extra $700,000 in revenue per year, while also garnering up to $2.8 million in donations for the development. The school has a total net-recurrent income of $27 million per year.