£3.3m investment to reduce storm overflows into the Calder and Hebble Navigation

Yorkshire Water is investing £3.3m at Combs Hill to reduce the number of storm water discharges, following periods of heavy or prolonged rainfall, into a tributary of the Calder and Hebble Navigation canal at Thornhill, nr Wakefield.

Contract partners, Morrisons Water Services (MWS), have started on site to construct a new 213m³ storage tank – 8.2m diameter and 8m deep segmentation shaft. The storage tank will hold excess wastewater during heavy rainfall and reduce the frequency of discharges into the tributary into the Calder and Hebble Navigation canal.  Once the rainfall has stopped, the stored wastewater will be pumped back into the network to be fully treated.

The project also features modifications and improvements to the existing combined sewer overflow (CSO) including the creation of a new weir wall with spill direction, as well as blocking the existing spill side.

Liam Thomas, project manager, Yorkshire Water, said: “We are committed to improving watercourses across Yorkshire and are investing £180m by April 2025 to reduce storm overflows and improve water quality across the region.

“Combs Hill is one of a number of large-scale infrastructure projects around Wakefield, West Yorkshire area that include £4.9m improvement works at Bridge Road, Horbury, £3.9m investment at Park Hill Farm CSO and £5.3m investment to reduce storm overflows at Notton CSO.

“It will help to reduce the number and intensity of storm discharges flowing into local watercourses following extreme wet weather events and should result in a 75% reduction of storm discharges into the Calder and Hebble Navigation canal on completion.”