Greening streets, retrofit rain gardens, Nottingham

    Solution ID
    Description of solution
    Summary (Challenges; Objectives)

    This pilot retrofit SuDS project was a result of collaboration between the Environment Agency, Nottingham City Council, Groundwork Greater Nottingham and Severn Trent Water. The construction phase was completed in May 2013.The scheme was designed to achieve the following objectives;<ul><li>Document and evaluate the design and construction of a series of rain gardens within an existing highway setting.</li><li>Maximise surface water interception, attenuation and infiltration.</li><li>Test the effectiveness of rain gardens in managing surface water from the public highway.</li><li>Encourage participation from local residents in the design and future management of the rain gardens.</li><li>Evaluate the effectiveness of the scheme as an engagement tool around the sources of urban diffuse pollution and flood risk.</li><li>Highlight the role that retrofit SuDS can play in improving the quality and reducing the volume of surface water flowing to urban watercourses.</li></ul>

    Technical characteristics

    A total of 21 linear rain gardens (total of 148m2) were constructed within the grass verge, allowing for the constraints of access, below ground services, street furniture and trees. The rain gardens utilise a combination of clean stone aggregate and proprietary units to create void space beneath a planted topsoil layer. They were designed to capture runoff from 5500 m2 of highway from a total surface area of 7100 m2.The remaining surface area could not be incorporated into the scheme due to a number of mature trees clustered in one section of Ribblesdale Road. The scheme was designed to manage surface water runoff from a 1:30 year event and to always intercept and treat the, often more polluted, first flush of highway runoff. Existing highway gullies have been retained to allow for overflow when the rain gardens reach capacity.

    Success factors / lessons learnt

    Benefits &amp; achievements<ul><li>SuDS retrofit scheme delivered through partnership</li><li>Proven surface water capture and infiltration leading to reduced pressure on downstream sewer and watercourse.</li><li>Increased understanding and awareness of the benefits of retrofit SuDS at a community and partner level. The following challenges were managed during the project;</li><li>Limited time to design and construct the scheme.</li><li>Varying support for the scheme amongst residents and general lack of understanding of how surface water contributes to flooding and poor water quality.</li><li>Safety concerns – residents and safety audit helped refine rain garden design</li></ul>

    Location Latitude
    Location Longitude
    Comment on location

    Ribblesdale Road, Sherwood, Nottingham, NG5 3HW.

    Ecosystem (s) impacted
    Hazard(s) concerned
    International classification
    Sustainable development goals addressed
    SDG 11 – Sustainable Cities and Communities
    Sendai Frameword priorities addressed
    Priority 3. Investing in disaster risk reduction for resilience
    Financial aspects

    Capital costs for the project were £68K. Staff time was also provided by Nottingham City Council and the Environment Agency. Groundwork’s time for design and community engagement was paid for by the overall project budget.The project delivered 148m2 of rain garden which equates to £460 per m2. The cost for rain gardens filled with aggregate was around £300 per m2 but was significantly more where attenuation cells were utilised.

    Is it possible to transpose this action in a different context?
    Yes, it is easily transposable
    Risk reduction