Flood alleviation measures installed on St Helens Transport Interchange

Article date: 15 December 2025

These trends are driving infrastructure improvements in towns and cities across the UK. In St Helens, the regeneration of the town centre and delivery of a state-of-the-art Transport Interchange have required installation of special underground tanks to ease pressure on the drainage system and reduce the risk of flooding.

The equipment - known as attenuation systems - has been installed as part of the programme of slab foundations being laid by the main contractor, VINCI Building, operating on behalf of St Helens Borough Council and ECF, a partnership of Homes England, Muse and L&G.

Attenuation tanks collect and temporarily store rainwater from roofs, paved areas and other impermeable surfaces. The water is diverted into the tank through a network of pipes and inlets. A flow control system then regulates the release of water back into the drainage system at a manageable rate, reducing the peak flow during heavy rainfall.

As urban areas expand, more land is covered by impermeable surfaces like roads, car parks and buildings. This increases surface water runoff, requiring engineered solutions like attenuation tanks to manage water locally. UK government policy, including the Flood and Water Management Act 2010 and the National Planning Policy Framework, has increasingly prioritised such flood mitigation measures

Martin Horton, Senior Project Manager at VINCI Building, said: "Attenuation systems have an important role to play in reducing the risk of flooding and future-proofing urban environments. They also offer significant environmental benefits to St Helens, such as improving water quality by filtering out pollutants.

"When installed underground, they are much more cost-effective and space-efficient than expanding traditional drainage infrastructure. By releasing rainwater steadily over time, they reduce the strain on drains, minimise wear and tear, extend the lifespan of existing infrastructure, and reduce maintenance costs."

The St Helens tank has a capacity of approximately 300,000 litres, helping to relieve pressure on the surrounding neighbourhoods near the bus station. The top of the tank sits around a meter below the road level.

Councillor Richard McCauley, Cabinet Member for Regeneration at St Helens Borough Council, said: "This is a once-in-a-lifetime regeneration project, and we have to consider measures that help the town now but will also be valuable for future generations. The UK is experiencing more frequent and intense rainfall events, which overwhelm traditional, often aging, drainage and sewer systems. The system we have installed for St Helens will store excess water temporarily and release it at a controlled rate, protecting the town centre from flooding."

Matt Whiteley, Senior Development Manager for ECF, commented: "The project team is delivering some complex engineering to ensure St Helens town centre has robust infrastructure. Attenuation tanks are a crucial tool in making towns and cities more resilient to flooding and the pressures of urban development in a changing climate. We're pleased with the progress, and this is another important milestone completed."

Cllr Steve Foulkes, chair of the Transport Committee at the Liverpool City Region Combined Authority said: "The installation of these rainfall attenuation systems is a prime example of how thoughtful, resilient design is being integrated into the build of this key piece of transport infrastructure for the region. They're yet another crucial element of the project to deliver a new interchange in St Helens town centre, which will better connect local communities with opportunity and each other."

The latest State of the UK Climate report from the Met Office shows the UK has become significantly wetter over recent decades. The period 2011-2020 was 9% wetter than 1961-1990. Days with very heavy rainfall - exceeding 95% and 99% of historical averages - have increased, as have extreme rainfall events exceeding 50mm. Both trends point to increasing frequency and intensity of rainfall across the UK.

Once complete, the St Helens Transport Interchange will transform travel for bus passengers, cyclists and pedestrians, creating a safe, accessible and welcoming gateway to the town centre.

Key features include 11 bus stands (up from nine) to support the region's bus franchising plans, temperature-controlled concourses, real-time travel information for both buses and trains, step-free access throughout, and automatic doors at every stand. The Interchange will also feature a Travel Centre, accessible toilets including a Changing Places facility, and secure indoor and outdoor cycle parking with improved wayfinding.

The surrounding public realm will be enhanced to improve connections between the Interchange, St Helens Central Rail Station, and key landmarks such as the Gamble Building, Theatre Royal, and the forthcoming Hampton by Hilton hotel. A new civic square, upgraded lighting and high-quality landscaping will create a vibrant, people-friendly public space.

The £35 million project is being delivered through £32 million from the Liverpool City Region Combined Authority via the City Region Sustainable Transport Settlement (CRSTS), alongside £3.25 million from the Government's Towns Fund and contributions from St Helens Borough Council.