Innovative eel pass lands top environmental award

Posted: Monday 7th April 2014

An ingenious new system to help baby eels (elvers) migrate up UK rivers has just been voted joint winner of the Environment Agency Project Excellence Awards 2014 for Innovation.

Hundreds of sites that have been almost impossible for elvers to reach in the past could, potentially, be opened up thanks to this groundbreaking technology.

Agency officers faced a major challenge when they was asked to design an eel pass for Bitton Weir on the River Boyd between Bristol and Bath. Surrounded by 9m high steel sheet piling river walls with a 4.5m vertical drop, the weir was a major obstacle to migrating fish. To add to the difficulties, there was no mains electricity at the site.

Undeterred, officers teamed up with Kingcombe Aquacare Ltd and came up with an original solution. Using technology dating back to the 18th Century, they installed a series of hydraulic pumps to provide a steady flow of water down a custom-made eel pass. A special fuel cell and solar panels provide the electricity for monitoring cameras and equipment on the site.

Kingcombe Aquacare fabricated sections of the eel pass at their workshop in Crewkerne, Somerset before fixing it to the vertical sheet piled wall of the weir channel. The bottom of the eel pass channel is covered in a bed of bristles that enables elvers to wriggle up over the weir. They are attracted by the constant flow of water coming down the eel pass.

Remarkably, elvers started using the eel pass almost immediately. Within 24 hours of its completion, several baby eels were filmed on the site’s CCTV cameras ascending the channel and reaching the upper waters of the river for the first time in decades.

The pass has opened up another 10 miles of the River Boyd to elvers and should help restore eel numbers that have suffered a major decline in recent years. The Boyd is a tributary of the Bristol Avon. Previously, the young eels only had access to less than a mile of habitat.

By harnessing energy from water tumbling down the weir to power hydraulic pumps, the scheme designers avoided the far more expensive option of having mains electricity installed at the site.

‘This was a challenging project that called for an innovative solution. We knew that if we could design and install an eel pass at this site would could put an eel pass in anywhere. We are very pleased our efforts have been recognised through the Environment Agency’s Project Excellence Awards 2014 for Innovation and that we have been selected as joint winner,’ said project manager, Gareth Varney.

'This eel pass is British engineering at its best. Working closely with the Environment Agency, we’ve produced a successful working prototype that has significant implications for similar sites across the UK and abroad. There are 26,000 recorded obstructions to fish passage in the UK. About 500 could be resolved using this solution. It could also be used at thousands of other sites across Europe. It’s carbon-neutral, sustainable, and cost effective,’ said John Colton of Kingcombe Aquacare.
‘I was thrilled when eels began using it so quickly and I’m delighted that we’ve won this award,' added Mr Colton.

Also involved in the project were AP Land Surveys who surveyed the site and Papa Pumps Lts who helped with the design and commissioning of the hydraulic ram pump system. The eel pass channel was supplied by S&D Plastics Ltd of Highbridge.

The other winner in the innovation section - the Severn Estuary Flood Risk Management Strategy – looked at the best way to manage more than 200km of defences and protect approximately 100,000 properties from flooding.

A key innovation within the strategy was to develop a method that could attribute habitat change to natural, uncertain or man-made causes. This helped influence national discussions between the Environment Agency, Defra and Natural England and has UK-wide implications. The work was underpinned by strong scientific understanding and political engagement.

Application of this innovation has turned it into a deliverable strategy; removing the risk of legal challenge. Early schemes around the Severn Estuary that protect around 50,000 homes from flooding can now progress without further habitat creation schemes, saving at least £5 million.

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