£9M stormwater tank protects River Tame

A major project carried out by North Midland Construction at Severn Trent's Willenhall sewage treatment works provides extra capacity for excess waste

North Midland Construction (NMC) is nearing completion of the construction of a vast below ground concrete storage tank that is part of a £9.2M project at Severn Trent Water’s Willenhall sewage treatment works. The tank has beenbuilt to provide extra capacity for stormwater during heavy rainfall and improve water quality in the River Tame.

Measuring 174m long and 20m wide and subdivided into twelve separate units, the tank has a total capacity of 20,000m3 and will reduce annual spills into the River Tame by nearly 80%. The construction of the tank followed a huge hydraulic modelling exercise undertaken by the Severn Trent’s asset creation sewerage solution team and subsequent river quality modelling. The project has had the backing of the Environment Agency.

NMC said that a number of issues had to be overcome on the project including contaminated ground, buried concrete structures, the presence of great crested newts and a complicated geology with a past history of deep coal mining and particularly high ground water levels. All the excavated materials have been reused on site, significantly reducing the cost of the project and the carbon footprint.

Simon Cocks, wastewater services director at Severn Trent, says: “This is a great investment as it protects the water quality in the River Tame and provides extra capacity for excess waste water during heavy rainfall which is particularly important as the effects of climate change are felt.”

Director of the civil engineering division of NMC Mark Blakeway says: “The project had significant technical and ecological obstacles to overcome, however the management team must be congratulated for working together to find the innovative solutions that enabled the project to be delivered successfully.”

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