At what point do you email picture to council planning officer, and building regs civil servant type who is so bored he'd piss himself with excitement. ?
Is the wall tied in? I wondwer what that little triangular bit that the pipes go into is for. Is there a drain in the triangular bit? I think you need to go on an expedition into the woods to gather more info.
the good news is that those blocks are so soft, you'll easily be able to drill through and insert a small camera to see what goes on maybe run a webcast - you'll have a few subscribers from this thread at least!
Just a slight diversion but if the saw was unable to cut through the hardened steel chain, I'd have used it to cut through the old pipe way before choosing what he did.