Case study:Lodge Burn cascade fish pass and culvert bed restoration (as part of the Lodge Burn FAS)
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- 1 Project overview
- 2 Image gallery
- 3 Catchment and subcatchment
- 4 Site
- 5 Project background
- 6 Reasons for river restoration
- 7 Measures
- 8 Monitoring
- 9 Additional documents and videos
- 10 Additional links and references
- 11 Supplementary Information
|Project web site|
|Themes||Fisheries, Flood risk management|
|Main contact forename||Gareth|
|Main contact surname||Greer|
|Main contact user ID|
|Contact organisation||Rivers Agency Northern Ireland (DARDNI)|
|Contact organisation web site||http://www.dardni.gov.uk/rivers|
|Parent multi-site project|
| This is a parent project
encompassing the following
The aim of the project is to install a new cascade fish pass to improve fish passage through a reach of the Lodge Burn in Coleraine as part of a wider Flood Alleviation Scheme. A perched culvert with a concrete apron outfall located in the center of the town was causing disruption to fish passage and sediment transport. The location of this structure meant that re-design of the reach had to work within a very confined space between two high flood walls, which encompassed installation of the cascade sequence and re-design of the culvert bed.
The works were carried out in four key stages; 1. Flow management; works to install the step pool sequence and improve the culvert bed had to be conducted in the dry. A fully isolated dry working area was achieved by sandbagging and over-pumping. 2. Modify culvert bed; it was necessary to ensure passability for fish through the culvert, therefore the new culvert bed was fixed 300mm below the previous bed 3. Install natural bed in culvert; from a mix of cobble and boulders 4. Remove concrete apron and install cascades Spacing between cascades was 6m, therefore in total the pass extended for 36m downstream of the culvert.
It was envisaged that some maintenance of the pass would be needed, so a demountable barrier was included in the floodwall design to facilitate channel access if required.
The project is an excellent example of what can be achieved to improve fish passage in a confined space. Cascade strength was a major consideration as failure of the top cascade would have left a perched culvert once again, therefore it was deemed better to over-engineer the first two cascades to ensure their long term stability. In terms of aesthetics the new pass has had a positive response, however flooding shortly after construction caused some damage to the face of the first cascade as well as gravel and cobble washout from culvert. This resulted in infilling of the pools, which was removed after flooding, and highlighted the importance of pool design incorporating sufficient self-maintaining processes i.e. sufficient flow through to maintain the pool depth. The remaining cobble within the culvert is now deemed to be stable.
Community Involvement - "Salmon in the classroom" scheme undertaken at a local primary school, fish release highlighted on BBC TV and local press.
Monitoring surveys and results
Catchment and subcatchment
Select a catchment/subcatchment
Other case studies in this subcatchment: Lodge Burn Flood Alleviation Scheme
Cost for project phases
Reasons for river restoration
Hydromorphological quality elements
Biological quality elements
Physico-chemical quality elements
Additional documents and videos