Dig Once, Green Twice: GLA guidance to retrofit green infrastructure across utility constrained streets
Helping to significantly increase the delivery of SuDS and trees to make our streets greener, cooler and more resilient
Our team has worked with the Greater London Authority (GLA) and partners to develop new guidance that will make it easier to retrofit sustainable drainage systems (SuDS) and street trees across London’s congested streets.
Climate change means London is at increased risk of flooding, and the need for more sustainable drainage is now widely recognised internationally and embedded in our national and local planning systems. In response, flood authorities are planning to significantly increase the delivery of SuDS and trees across the capital.
London-based targets will require 7,000 hectares to be drained to SuDS features across the capital by 2050. To achieve this ambition, without significant disruption to the city’s transport infrastructure and communities, it’s essential to pilot and significantly scale the collaborative delivery of SuDS and trees.
Our team worked with Greater London Authority (GLA) and other partners, to develop a guidance that will enable SuDS and trees to be installed alongside planned utility streetworks across London’s boroughs.
We engaged closely with stakeholders, including utilities providers, contractors, local authorities and academics, to develop practical guidance for how and where SuDS and trees can be reinstated in the future. The project will help to create a greener streetscape, reduce flood risk and improve London’s climate resilience.
Our team provided the civil engineering expertise and visual design on the project, collaborating with landscape architects Bradley-Hole Schoenaich Landscape (BHSLA), with support from Ben Rose at Stockholm Tree Pits, and Meristem.
Katrina Wylie, associate and civil engineer at Civic, commented: “SuDS and trees are powerful ways for us to collectively respond to the impacts of the climate crisis and worsening flood risk. As we see throughout our work across the UK and Ireland, the use of SuDS and public realm improvements can bring real value and positive impact for climate resilience, flood mitigation, creating greener places and happier and healthier neighbourhoods and communities as well.
“It’s vital we provide the tools and expertise that will support the wider rollout of SuDS across London. We’re proud to be working with GLA and the wider project team to develop this new guidance, which we understand to be one of the first of its kind in the UK. We’re working closely with many teams across the sector to understand the challenges and opportunities they face and using these insights to create a practical framework for retrofitting SuDS across our streets, forming a key part of London’s climate adaptation.”
It is the GLA’s position, that by using planned street works as an opportunity to reinstate trees and SuDS, we can scale delivery far more quickly and make our streets greener, cooler and more resilient. But to do that confidently, boroughs, utilities and contractors need clear, practical and agreed technical guidance that shows how trees and SuDS can coexist safely with buried services.
The project kicked off in Autumn 2025 and recently completed. It forms part of the GLA’s wider programme of resources to support the delivery of trees and SuDS.
It’s the latest nature-based guidance shaped by Civic, that aims to improve our streets, towns and cities in response to the climate crisis. Our team has also co-authored SuDS guidance for Transport for London (TfL), which sets out how SuDS can be seamlessly integrated into London’s streetscape and public realm, as well as Greater Manchester’s Sustainable Drainage Design Guide with the GMCA, and guidance for the National Transport Authority of Ireland to support the retrofit of nature-based solutions in existing streets and along new active travel corridors.
