Case study:Longbridge West
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Project overview
| Status | Complete |
|---|---|
| Project web site | |
| Themes | Flood risk management, Habitat and biodiversity, Social benefits, Spatial planning, Water quality, Urban |
| Country | England |
| Main contact forename | Phoebe |
| Main contact surname | Ryding |
| Main contact user ID | User:PhoebeRyding |
| Contact organisation | PJA |
| Contact organisation web site | http://https://pja.co.uk/ |
| Partner organisations | St Modwen Developments Ltd, ACS Ltd, OBriens Ltd & Wakemans |
| Parent multi-site project | |
| This is a parent project encompassing the following projects |
No |
Project summary
The River Rea, and Callow Brook tributary, flows through the original site of the MG Rover Factory West Works in Longbridge, Birmingham, in a formerly hard-engineered, canalized and culverted channel.
In 2005, following the collapse of MG Rover, St Modwen Developments Ltd. purchased the former factory site with the aim of creating a sustainable place for people to live and work. Core to this aim, was a commitment to the restoration and re-naturalisation of the River Rea and Callow Brook. In 2008, the first factory buildings situated on the former West Works Site were demolished which included daylighting the majority of the River Rea. The watercourse through this area then remained largely un-altered until works progressed in this area of the West Works Site in 2019.
A two-phase approach has been undertaken to re-naturalise and restore the River Rea and Callow Brook through the West Works Site. The first phase of the re-naturalisation comprised approximately 200m of the River Rea, which was constructed offline in 2019-2020. In the following two years, the second phase, comprising the remaining 750m of the River Rea (an Environment Agency Main River) and 100m of its tributary, the Callow Brook (an ordinary watercourse), have been restored in a two-stage, green-blue corridor offering biodiversity enhancements, amenity space and online flood mitigation storage.
Both phases of work comprised extensive removal of hard-engineered structures lining the existing banks and bed of the watercourses (which included a concrete river bank and bed, sheet piling, bag work, a number of derelict former bridge crossings and brick walls) to enable construction of a two-stage channel with provision of online attenuation storage. These works have also created new public open spaces within the adjacent River Park, with a new pedestrian/cycle crossing and separate vehicular crossing to enable a sustainable green link adjacent to the river. In addition, the online attenuation storage generates a significant reduction in existing flood risk for the downstream areas of Longbridge Town Centre. With regard to ecological enhancement, a gravel bed integrating riffles and pools has been constructed, complimented by a diverse variety of native planting throughout the two-stage channel, with three stilling pools with varying wet-dry nature to provide different habitats for wildlife. Furthermore, Natural Flood Management (NFM) measures have been embedded, with ‘leaky dam’ features to ‘slow the flow’ within the flashy, urban catchment and provide erosion protection.
Monitoring surveys and results
Throughout the construction, weekly design team meetings were held with the whole project team and twice weekly site walkovers were undertaken with both engineering and landscaping specialists. This ensured that the wider collaborative vision for the renaturalisation of the watercourse was achieved.
Further to this, regular calls with both the Environment Agency and Birmingham City Council, in their role as Lead Local Flood Authority, were undertaken; with the Environment Agency undertaking site walkovers throughout the construction of the river works to ensure any further design considerations could be realised prior to completion.
Throughout the design and construction of the works, priority has been given to realising the multifunctional benefits for both the river corridor itself and surrounding communities. At the heart of the restoration is the creation of new habitat, which has been monitoring and dynamically adjusted throughout the construction. The design principles of the river corridor allow for natural variation and adjustment of the watercourse, thereby ensuring longevity in the habitats created.
Lessons learnt
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