Pretty much all the hardcore done, bar the space around the duct for the water pipe:

We didnt think we could push the water pipe through the duct after it's concreted over, so we're going to insulate the pipe and connect the duct around it, then place it in the space we've left and fill the rest of the hardcore up around it. We'll have to manually compact the stuff around the duct, because the machine might crush it!

Nearly there :)