Case study:Longbridge West: Difference between revisions

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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.  
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.
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.
|Project title=Longbridge West
|Project title=Longbridge West
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Location: 52° 23' 47.55" N, 1° 59' 29.13" W
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Project overview

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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

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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

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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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Catchment and subcatchment

Catchment

River basin district Humber
River basin Tame Anker and Mease

Subcatchment

River name River Rea from Source to Griffins Brook
Area category 10 - 100 km²
Area (km2)
Maximum altitude category 200 - 500 m
Maximum altitude (m) 299299 m <br />0.299 km <br />29,900 cm <br />
Dominant geology Calcareous
Ecoregion Great Britain
Dominant land cover Suburban
Waterbody ID GB104028042510



Site

Name Longbridge West
WFD water body codes GB104028042510
WFD (national) typology
WFD water body name Rea source to Bourn Brook Water Body
Pre-project morphology
Reference morphology
Desired post project morphology
Heavily modified water body Yes
National/international site designation
Local/regional site designations
Protected species present No
Invasive species present No
Species of interest
Dominant hydrology
Dominant substrate
River corridor land use Urban
Average bankfull channel width category
Average bankfull channel width (m)
Average bankfull channel depth category
Average bankfull channel depth (m)
Mean discharge category
Mean annual discharge (m3/s)
Average channel gradient category
Average channel gradient
Average unit stream power (W/m2)


Project background

Reach length directly affected (m) 200200 m <br />0.2 km <br />20,000 cm <br />
Project started 2019
Works started
Works completed
Project completed
Total cost category
Total cost (k€)
Benefit to cost ratio
Funding sources

Cost for project phases

Phase cost category cost exact (k€) Lead organisation Contact forename Contact surname
Investigation and design
Stakeholder engagement and communication
Works and works supervision
Post-project management and maintenance
Monitoring



Reasons for river restoration

Mitigation of a pressure
Hydromorphology
Biology
Physico-chemical
Other reasons for the project


Measures

Structural measures
Bank/bed modifications
Floodplain / River corridor
Planform / Channel pattern
Other
Non-structural measures
Management interventions
Social measures (incl. engagement)
Other


Monitoring

Hydromorphological quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative

Biological quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative

Physico-chemical quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative

Any other monitoring, e.g. social, economic

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative


Monitoring documents



Additional documents and videos


Additional links and references

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Supplementary Information

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