I had heard of a rather large brick overflow, having seen nothing else in the area that fitted the description I went to check it out. The outfall into the Irwell was a non starter as it was mostly underwater with only the top of a brick arch showing.
A rather nicely concealed upstream lid granted access to a chamber I remembered seeing on subexposure some time ago. The upper section looked down past large iron beams that made up the roof of an older looking overflow chamber below.
The chamber serves an 8ft sewer, overflow weir and the brick overflow pipe I had been looking for. Unfortunately it was thigh deep in river level water which slowly rose and fell with it's load of rubbish from previous overflow events.
The pipe was smaller than I thought it would be so didn't bother with the nasty wade down to the river. Although a small explore it was still nice to figure the place out.