Greener Grangetown

Greener Grangetown is a retrofit sustainable drainage scheme near Cardiff city centre. The design utilises green infrastructure to future proof the drainage network, removing 4.4 hectares of impermeable area from the combined sewer whilst delivering improved biodiversity, enhanced public realm and promoting sustainable travel.

A key project objective is to enhance the visibility of water by creating green-blue corridors. This will encourage people to understand and value sustainable water management. The scheme comprises 12 residential streets, intercepting surface water runoff from roofs and highways, and conveying it into a total of 108 individual rain gardens. These cleanse the runoff before water is discharged to the nearby River Taff.

From the outset, regeneration and improvements to the public realm were key objectives.

The integrated approach stems from a unique partnership of Cardiff Council, Dŵr Cymru Welsh Water and Natural Resources Wales.

The landscape architect’s role has been a fundamental part of the scheme. The landscape vision was prepared and carried forward by Arup landscape architects throughout the various project phases:
- Feasibility: establish and refine the landscape concept from the client’s brief, site analysis, constraints and opportunities
- Concept design: develop the refined landscape concept with sufficient information for costing
- Detail design: develop the landscape concept into a hard and soft detailed scheme for construction
- Implementation: continuous liaison with the main contractor, respond to their queries and supervise the landscape works

This pilot project is recognised as industry leading by policy makers including Welsh and Northern Ireland governments, along with water companies and local authorities from around the UK.

Community engagement provided an opportunity for residents to input towards the design of their streets. Engagement has continued throughout construction with weekly drop-in sessions, planting events and social media updates.

The benefits to the environment are noticeable and they try to tackle some of the main issues we are facing nowadays such as climate change, socio-economic inequality, biodiversity and habitat loss and high pollution levels.

With new legislation emerging in Wales that will make SuDS compulsory for all new development, this scheme is a unique example of how we can all work together to be more sustainable.

The innovative delivery approach is mirrored by the design. Water is kept as close to the surface as possible rather than buried. Recycled kerb and channel drainage features intercept and convey water through gravity into rain gardens, highlighting its journey.

Planting trees in urban environments is proven to have numerous benefits, but also many challenges. An early objective has been that the new 120 trees could develop to maturity. In order to achieve this with confidence the tree pits were designed and specified after a long process of research and guidance from manufacturers and soil scientist.

The scheme is delivering a major improvement to the cycle network in Cardiff through collaborative design with cycle groups including Sustrans. A new 555 metre Bicycle Priority Street will be one of the first in the UK.

Both pedestrian and cyclist movements have been improved throughout the scheme with new crossings and raised junctions providing at the same time better visibility and safety.