Project Details

Client: Bailey Contracts Ltd (Overall client Ribble Rivers Trust)

Categories: Detailed Design, Fish Pass Design, River Restoration

When: Jan 2020 - Mar 2021

Location: Clitheroe, Lancashire, UK

In 1787 a 7 metre high dam was constructed to provide water to power a cotton mill at Primrose Lodge Mill, Clitheroe, in the Ribble Valley. Whilst the dam is no longer utilised for local industry, the site has been designated a Biological Heritage Site, so the natural flow of the river cannot be re-established, however, it is hoped that the Ribble Rivers Trust project will soon see Salmon, Sea Trout and Eels returning to their ancestral spawning ground. To this end, our clients, Bailey Construction, were commissioned by the Trust to install a Fish & Eel Pass as part of the construction works being undertaken at Primrose Mill. Bailey’s subsequently commissioned Edenvale Young to provide the Detailed Design of the support structure.

Fishes & Eels return home

Complex Design Challenges

“…the adaptive, reactive and innovative thinking required on this project was intense, you guys rose to the challenge on the design front!!!”

Jack Spees, Ribble Rivers Trust

Detailed Design of Fish & Eel Pass

The whole scheme was very complex due to the constrained nature of the site and this required close working between our senior engineer and the site manager, often requiring the design to be adapted quickly when new issues arose on site. The road bridge, passing at an angle over the crest of the spillway, presented a number of complex challenges to the design including headroom; the fish pass was required to pass within 350mm of the bridge soffit. Additionally one of the resting pool tanks was positioned beneath the bridge, on the spillway and on top of a culvert outlet. This required an unconventional approach to the supporting plinth. Edenvale Young were responsible for the following elements of the design:

• Reinforced concrete intake channel.
• Modifications to the spillway crest.
• Design of resting pool tanks including fabrication drawings.
• Design of supporting structures to resting pool tanks.
• Setting out details of the works.


Working closely with all parties, from our immediate clients Bailey Construction, the Ribble Trust and those fabricating the Alaskan Units, and after delays due to inclement weather, the Fish & Eel Pass was finally bolted together with a margin of error measured to a few millimetres.

The Primrose Lodge Fish & Eel Pass is part of a wider project involving the Ribble Rivers Trust, if you would like to find out more about what they do, please follow the link here. Ribble Rivers Trust

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