Drainage issues

One source of damp in this place is coming from the vicinity of this drainpipe which does not drain anywhere but just straight onto the ground. Trying to come up with solutions for how to drain it, I had the bright idea of fitting a water butt. Great idea but the jaunty video on B&Q shows a man quickly hand-sawing through a plastic drainpipe to fit it. This one is cast iron! An exploratory poke shows that this pipe is half coming apart at the join which is probably also adding to the damp.on the other side of this wall.