A balancer between the A and B Outfall sewers with penstocks to enable throttling between pipes.
The brook emerged from a tiny brick culvert around a foot high, but downstream a few meters was the outfall for what I presume to be the brook's bypass.
Prestwich clough had a promising looking if not slightly dodgy culvert. The brick filled wire cages sagged rather in the middle and the concrete roof beams looked compromised from the weight above.
Heaton Park has various small waterways snaking through it, when I first saw the sunken channel I presumed culvert. It was in a clearing in a wood, and had concrete surface structures that suggested something going on underneath.
After doing Bypass, toothdoctor and myself found ourselves in Rainbow Junction. The downstream culvert of Macro leads on from this, it's double barreled at the infall, but opens up to 3 someway in.
A short water slide greeted us almost straight away and hinted this was going to be good. The box section soon opened up into a beast of a 12 ft RCP, Before long a large shaft rose above the pipe.