This CSO system is Heywood's largest overflow into the River Roch, I met with Nckt for a look. It consists of 3 separate sewer overflow connections which meet before dropping into a culvert to the river. The system has been modernised with most sections replaced or given a concrete lining.
The first connection drops down in a large circular chamber before a dropshaft into the overflow culvert. The shaft goes down around 10ft giving a glimpse of a much older looking flooded section below.
The brickwork shows through on a couple of arches and in a tall chamber, the next connection meets just after the first arch.
This connection is from a sewer that runs overhead in a channel through a small screened CSO chamber. Any overflow drops down both sides of the channel into a chamber with a small weir and onto the connecting tunnel. The sewer continues through a concrete box that bridges the chamber below.
The connecting tunnel ends at the final standard looking CSO chamber.
The combination of large chambers and use of vertical space all made this an interesting explore, although I would love to see what the system was like in it's original brick incarnation.