National Highways–WSP water quality plan: retrofit drainage lens for engineers
Reviewed by Tom Sullivan

First reported on The Construction Index
30 Second Briefing
National Highways has appointed WSP as technical partner, supported by Mott MacDonald, Ramboll, Arup and Aecom, to deliver its Water Quality Plan targeting the most polluting road run‑off discharges on the Strategic Road Network by 2030. The programme will design and implement treatment for high‑risk outfalls using nature‑based systems (e.g. swales, wetlands) and mechanical solutions installed within existing highway boundaries, focusing on oils, tyre‑derived suspended solids and brake‑related metals. For designers and geotechnical teams, this signals significant upcoming work on retrofit drainage, attenuation and treatment assets constrained by current carriageway footprints.
Technical Brief
- Consortium (WSP, Mott MacDonald, Ramboll, Arup, Aecom) provides programme leadership, technical assurance and delivery support.
- Designs must remain within existing highway boundaries, constraining footprint for treatment, attenuation and access structures.
- Interventions must be “targeted and proportionate”, implying tiered treatment levels rather than uniform design standards.
Our Take
National Highways appears repeatedly in our Environmental coverage, with other pieces highlighting low‑carbon construction trials and hydrogen‑fuelled plant, so appointing WSP on a Water Quality Plan 2030 signals that environmental performance is now being embedded across both carbon and aquatic impacts on the UK strategic road network.
The 2030 time horizon for this Water Quality Plan aligns with other National Highways initiatives in our database that are tied to medium‑term performance periods, which likely means water quality interventions will need to compete for funding and delivery slots alongside decarbonisation and asset renewal schemes.
Prepared by collating external sources, AI-assisted tools, and Geomechanics.io’s proprietary mining database, then reviewed for technical accuracy & edited by our geotechnical team.


