Storm Sewage Outfall, Spa, Slaithwaite

Image: © Humphrey Bolton Taken: 16 Aug 2007

Most of the old sewers carry rainwater from roads and roofs as well as sewage. In the old days the sewage works for Slaithwaite was in what is now part of a highways depot, behind the outfall bay. For various reasons the treatment of sewage has been centralised, and in the mid-20C a sewer was laid down the valley to connect with the Huddersfield system at Milnsbridge. It is not affordable to install the enormous pipes that would be necessary to carry all the surface-water runoff down to the Huddersfield sewage works at Deighton, and in any case the works could not cope with the large flows that occur during rainfall. There is therefore an overflow at this point, and it was reconstructed using the latest vortex design when the inlet sewer had to be relaid at a lower level in order to allow the canal to be reopened. This was because a lock on the canal was to be relocated further upstream, and also a sewer pipe-bridge had been constructed across the canal around a metre above water level.

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