As part of a £90 million scheme to improve the quality of the River Calder and River Spen, Yorkshire Water undertook an extensive programme to upgrade their Waste Water Treatment Works (WWTW). Met Consultancy Group (Met) designed and detailed a large portion of the works including a Water Retaining Aeration Tank.
Originally the discharge into the Calder and Spen River’s did not meet the effluent discharge consents. A strategic study by Freshwater Fisheries Directive (FFD) identified the optimum solution to meet the discharge consent. This identified the need for three separate treatment works at North Bierley, Spenborough and Spen Valley, with the waste water being transferred to an upgrade site at Spen Valley in Dewsbury. Upgrading Spen Valley would provide a modern waste water treatment facility with provision for future extension.
The works were designed to improve the biological, chemical and aesthetic quality of the water discharged into the River Calder and River Spen, delivering real benefits for the local environment and encourage the return of fish and wildlife.
Met were contracted to design and detail:
- Water Retaining Aeration Tank
- Final Settlement Tanks
- Two steel framed buildings
- Pipeline support
- Thrust blocks
- Gantries, and
- Green Waste Processing Facility (this enabled recycled material and sewage sludge to be combined producing a compost product that is re-used locally).
The most impressive element of works to design and detail was the Water Retaining Aeration Tank. This structure (equivalent in size to two football pitches) stores and aerates waste water before being transferred to the Final Settlement Tanks.
For its size, the structural design needed to provide a strong and watertight structure holding many megalitres whilst providing the best economical solution. The initial design stage thoroughly investigated numerous solutions before settling on un-lined, reinforced, watertight concrete, cantilever walls.
The search for cost savings innovated Met to develop software which enabled accurate comparisons to be run for wall thickness against reinforcement tonnage across various wall heights and loadings therefore determining the best economical solution for the project.