Interesting that the AI has the stuff pouring out of both ends of the pipe - presumably there is a duckweed breeding facility at the base of the column?
I let it off by observing what appears to be a third connection just behind the pump. Near where the driver is stood there is something going into the ground. My rationale is that the duckweed is somehow pumped in there and then unsuitable weed is sent back to the canal.
But that said, Bionic Duckweed is magic so maybe it grows faster than the train can take and the rest has to be dumped into the canal?
Although it will be corrected one day, currently AI has no concept of context. I asked for an unplugging and got one end of the wire with an unplugged plug. The other end of the wire was plugged in. Rather defeated the point of what I wanted, and also leaving the question of what on earth the wire actually did.
It is possibly unrealistic to use Mallard as the test locomotive. I rationalised that because it was Mallard used for the speed record, so the locomotive had already been a test loco in history.