Lessons learned from fish pass and river restoration design projects

When approaching fish pass design, there is a growing tendency amongst designers to default to a Larinier solution: the resulting hydraulics are thought to accommodate most UK fish species so, when designed well, the Environment Agency National Fish Pass Panel are normally receptive to their application in many circumstances and they aren’t particularly complex structures to build.
However, every site is different. A blindingly obvious statement, but it’s true. This means that regardless of the simplicity of the solution, every site has its own challenges that need to be carefully considered if a design is to work for the regulator, the client, the contractor and whoever is operating the pass in the future.

Here are some lessons learned from the past 18 months of fish pass and river restoration design that a project team would benefit from considering.

  • Develop and agree a list of core project objectives with the client at project inception, and ideally involve the regulator in this process. Having clarity on which objectives, including designed-for species, are core and which are niceties will enable a transparent, efficient and focused design process.
  • The above objectives should include a clear definition of the spatial scope of the project, and more specifically, that any survey work carried out gathers enough information to ensure you only need to go to site once.
  • Where possible, use a 3D CAD platform in which to do your design. Representing the existing structure, proposed engineered solution and current and predicted water levels in a 3D model makes it much easier to identify clashes that could compromise a design and that therefore need to be designed out. On completion of the hydraulic design, this model can then be used in detailing the structural design. This approach is also more in line with the principles of Business Information Modelling (BIM) which government contracts are increasingly having to comply with.
  • Involve the end user in the design process, where possible; this may not be the direct client. Make sure provision is made for safe operational phase maintenance access is as important as getting the hydraulic design right (see our blog in the next couple of days regarding fish pass design and the Construction (Design and Management) Regulations).
  • Similar to the above, early contractor involvement in the design process will help with buildability and keep construction costs down.

Building all of the above into your design delivery programme will yield significant whole life project cost savings and help to ensure the regulator, client and design team are kept happy and everyone goes home safe at the end of the day.

Want to know more?

Email Dave Mould for more information on fish passage design. You can also find out more on our Fisheries web pages.

Are you attending the River Restoration Conference on 24-25 April? We’ll be showing you how our catchment and river restoration team deliver innovative and sustainable solutions to improve our rivers and catchments.

We are giving four presentations and have eight posters for you to see our project examples. Read the abstracts to find out more in our interactive guide below.

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