HFLB - Manchester
An overflow from one of Manchester's main interceptor sewers. Following through the outfall and into the overflow chamber a staircase leads to a platform looking down above the flow. The design allows for the river to overflow into the sewer line in times of flood. The penstocks allowed the system to block river water from flowing into the sewers.
By positioning a penstock slightly above the usual flow level, it would permit a steady amount of sewage to pass into the downstream sewer while largely preventing river water from entering. This does however mean that someone would have to physically be there to adjust the penstock, raising or lowering it based on typical flow levels and storm intensity, another reason why the controls are in a separate room above away from the dangers below.
These were installed after 1896 in a lot of sewage chambers making the alternative outfall flaps redundant. Through the penstock a roaring sound can be heard which is actually a steep drop leading into presumably a sump. A prime example of Victorian ingenuity.
