M6 Flood Mitigation

Location: M6 Lancaster
Service: Drainage Renewal Design & Flood Mitigation
Status: Detailed Design Approved – October 2024

Overview

Courous Ltd was appointed to tackle persistent flooding at a high-risk stretch of the M6 southbound near Lancaster. With 9 recorded flood events and a Category A (Very High) flood classification, the scheme focused on upgrading drainage infrastructure .

Challenge

The existing drainage system featured limited gully capacity, pipe obstructions, and outdated layouts. Most surface runoff collected in the central reservation, where a lack of adequate outlets and buried pipes beneath a concrete barrier further exacerbated flooding risks—particularly in Lane 3.

Additionally, two chambers located within the hard shoulder needed relocation in line with CD534, and the use of linear drainage required.

Our Solution

Courous Ltd delivered a pragmatic and compliant drainage renewal solution, including:

• 180m of dig-down pipe repairs, 44 patch repairs, and 582m of pipelining

• Linear drainage introduced in the central reservation to directly connect to chambers without disrupting the central barrier

• Two new chambers relocated from the hard shoulder to the verge

• Drainage modelling confirmed the system’s capacity, even under 1-in-100-year storm events with 40% climate change allowance

Outcome

The new drainage system mitigates flood risk while maintaining all runoff within the highway boundary—even in severe rainfall events. The use of Linear drainage, ensures improved collection and flow performance while avoiding deep excavations under traffic-sensitive areas.

Conclusion

This project demonstrates Courous Ltd’s expertise in balancing design innovation, regulatory compliance, and real-world constructability. The M6 scheme showcases our commitment to enhancing asset resilience for National Highways through data-led, future-proof drainage engineering.