Welsh Water hails completion of large new Chester surface water drainage tunnel

The only not-for-profit water company in England and Wales has been working with the council on the completion of its new surface water drainage system to support the regeneration of the area and to ensure the drainage system is more resilient to cope with the effects of climate change.

Welsh Water is due to take charge of the drain from this summer.

As the Council has been redeveloping a significant part of Chester - part of its One City Plan - Welsh Water’s Developer Services team, which manages the provision of water and drainage services to all new development, has been working closely with the council to identify how they can improve the management of the area’s surface water together whilst enhancing environmental outcomes. The £777m One City Plan is CWAC’s 15-year strategy for the future economic regeneration of Chester.

Historically, rainwater run-off from the roofs of buildings and impermeable surfaces such as highways in Chester’s city centre has drained to Welsh Water’s sewerage system, which is where surface water and foul water are combined before being carried to the Wastewater Treatment Works.

As a result of this historic arrangement, Welsh Water unnecessarily treated rainwater at its Wastewater Treatment Works and this sometimes resulted in heavy rainfall taking up all the capacity of the system, resulting in less room being available to support new development and regeneration.

It also led to occasional emergency releases of treated waste into the River Dee, which Welsh Water said was necessary to prevent internal flooding to homes and businesses in the area.

It is anticipated the new drainage tunnel will remove the need for that.

This significant redevelopment of Chester created a once-in-a-generation opportunity to recover the existing sewer’s capacity by removing the existing surface water. Welsh Water and CWaC wanted to find a solution that would not only support the redevelopment objectives but also improve the local environment and enhance the drainage system’s resilience to support the existing community.

Working with Welsh Water, the council decided to do things differently, and created a new 1km surface water drain through its city centre.

The new drain can handle one tonne of water per second and will serve an area of around 50,000 square metres – which equates to around nine football fields.

Stephen Beauchamp, Regions Director OTB Tunnel Project Managers; Chris Hindley, Cheshire & Warrington LEP; Henry Jones-Hughes, Dwr Cymru Welsh Water; Cllr Samantha Dixon; Rob Symons, Vinci Construction; Andrew Lewis, Chief Executive, CWaC.

Welsh Water has been collaborating with the council during its construction, and now the drain has been completed, Welsh Water will be taking on the ownership and responsibility for the management of the drain from summer 2022.

The new surface water drain now takes all rainwater back out to the River Dee, helping to:

• Increase the capacity of the existing sewer to support future development in the area
• Reduce the amount of water going to the Wastewater Treatment Works, reducing the energy and carbon used as a result
• Protect the local environment and river water quality and enhance the area’s climate change resilience

Removing rainwater from the sewerage network is a strategic objective of Welsh Water. Its RainScape projects see it using solutions such as swales and other sustainable drainage solutions to better manage the amount of surface water entering its sewers which in turn reduces the risk of flooding and benefits the local environment.

Councillor Richard Beacham, Cabinet Member for Inclusive Growth, Economy and Regeneration, said: “I would like to thank everyone in Chester who has been impacted by these works for their patience and understanding; I recognise that at times the works have caused frustration, but I hope residents have come to understand the significant economic, social and environmental benefits of constructing the new drain, which has been the biggest infrastructure project in our city for over 50 years.

“Completing the new drain has been a massive undertaking and it has required expertise from many contractors working in partnership to assist us. I would also like to thank them for all their hard work and commitment to this complex project.”

Ian Wyatt, business customer services director at Welsh Water, said: “We’re thrilled that CWaC’s innovative approach to managing surface water in the new redevelopment area is now complete.

"Climate change is a huge challenge for us all and it’s only by doing things differently and working collaboratively that we’ll be able to adapt effectively. This investment will benefit the local community and environment for many years to come and has an added bonus of increasing the capacity in the existing sewers, supporting Chester’s future development. When it comes to managing surface water, our developer services team is always open to working with stakeholders and developer customers on new approaches.”