I love this. This is the kind of work I used to do. I rebuilt many of these old pump stations in my time with Flowserve. Its a pity you couldn't get down to see the size of the actual pumps.
If you look between the motors on the last picture you can see one of the spare impellers that actually move the pump, this looks to be about 120cm diameter, and there would be 2 of these impellers per pump.

To give you a rough idea of size of the pump under the floor, you would be looking at a pump standing around 4m high, weighing in excess of 20Tonne. The entire case would be split down the middle to expose the shaft and impellers.

These are truely fun bits of equipment to work on and rebuild. Each part of the pump would be handmade.

If you get a chance, you should try to get out to Castlemaine and see the Flowserve, Thompson Kelly Lewis foundry, I think there is a museum out there.