Some of you may have been aware of the drain upgrade occurring on Port Road, on the western end.
It looks like they're pulling out the old drain, rectangular 2100 x 900 from 1944 (according to the SA government location service), and replacing it a round drain, maybe something like 1 metre in diameter.
It's got interesting near the point where there is common flooding. There's some sort of structure being built deeper in the ground.
Attached are a few photos. You can see the original drain in these photos.
Keep an eye on this one, it will be interesting to see what is constructed under the ground here!