it does look like Gahnia aspera. Could it be planted ? Garden escape ? This location here in ACT is outside its natural range (as given by herbarium specimens). There are no herbarium specimens for ACT. I'm not confident enough to confirm: Other Moderators need to have input, and may be more familiar with plant.
Definitely a Gahnia and not Gahnia subaequiglumis the only Gahnia currently considered to naturally occur in the ACT. Its location suggests it could be planted. I am not confident to confirm ID but it seems consistent with G. aspera. It also could possibly be a natural range extension.