SuDS in action

At Flood & Civil, we’re always exploring creative and practical ways to manage surface water sustainably. In our latest concept design, we’ve been reimagining the potential of road verges along a steeply sloping street to deliver multiple benefits — from flood risk reduction to biodiversity and placemaking.

In this scheme, we have introduced a series of bioretention raingardens along the verge to intercept surface water runoff, improve water quality and reduce pressure on downstream drainage networks. The design also includes new tree planting, carefully selected to complement the existing street scene while enhancing biodiversity and amenity along the route.

Understanding the challenge

At the upper end of the road, a public right of way from a local park slopes steeply towards the carriageway. During heavy rainfall, this creates a natural pathway for overland flow onto the road, contributing to flooding along the route and at the lower junction where levels flatten and water can accumulate.

By positioning raingardens strategically along the verge, the design provides storage and retention for exceedance flows, helping to slow and manage water before it reaches the downstream network. This eases pressure on existing infrastructure and reduces overall surface water flood risk.

Key features of the concept

The design incorporates several elements to maximise performance and resilience:

• Check dams to cascade flows and maximise storage along the system

• Angled inlets to optimise water capture from the sloping catchment

• Context-sensitive planting and new trees to enhance biodiversity and visual amenity

• Overflows and flow controls to manage exceedance while limiting discharge (subject to infiltration testing and hydraulic design)

• Gentle but effective depressions to create storage and reduce the risk of inlet clogging

  
  

Designing with the future in mind

As with all concept designs, this scheme highlights important considerations for further development. A detailed understanding of the drainage catchment area and peak flows will be required to accurately size flow controls, overflows and storage volumes. Infiltration testing and hydraulic modelling will also be key to refining the design and ensuring long-term performance.

If you’re interested in innovative SuDS design that manages surface water sustainably while enhancing the public realm, we’d love to hear from you.

Get in touch with the Flood & Civil team to explore how we can support your next project.