Island Roads Eel Pass

 

Site

Holbrookes, Isle of Wight

Installed

April 2017

Team

Artecology, Arc Consulting, Island Roads, Environment Agency

 

A site-specific innovation, the rationale for Artecology’s sculptured eel pass project grew out of straightforward ecological mitigation following essential repairs to a road culvert on an Island watercourse called the Holbrookes Stream. The highways PFI team at Island Roads, working with the Environment Agency, agreed on a method for the repairs which entails pulling through a plastic sleeve and curing with UV, quick and effective but inevitably leaving a step-up into the culvert for any aquatic wildlife moving upstream. Holbrookes also had a significant drop-off from its concrete spillway into a large scour-pool below and so the opportunity to fix the culvert step became an opportunity to more significantly reconnect water levels between downstream reaches.

Eel migration is a high priority objective in river work and this was our focus too. But we wanted to move away from standard ‘eel-only’ fixes and try instead a new way to retrofit structural improvements that could rapidly and cost-effectively facilitate physical connectivity within the stream but, crucially, deliver new, useful and permanent built enhancement to the habitat quality around the culvert for as many species as possible.

The result was our ‘Heart & Dart’ tiled system, retrofitted directly onto the existing infrastructure, consisting of a steel-framed ramp lined with the eel tiles, joined to a kerbed 3-tile-wide ‘pavement’ running up and into the culvert mouth. The ramp and tiles were made in the studio and installed on site over 2 days. The design is intended to provide the flow-control and textured purchase for eels to move upstream combined with a very large surface area folded into the tile array, creating great surface complexity with abundant niches and micro-sites for colonisation and wildlife activity.

 
 

Project Outcomes:

 

1.

River connectivity restored for high priority migratory species such as European Eel. Micro-site habitat creation to support additional riparian species.

 

2.

A successful ‘beyond-compliance’ partnership project for Island Roads which now informs the PFI approach to other infrastructure projects, from bridge and cycleway upgrades featuring built habitats and pollinator hotspots, to Artecology-inspired bee and lizard breeding and wintering niches in wall repairs.

Island Roads and the Environment Agency were highly commended in the Client category of CIRIA’s Big Biodiversity Awards 2017. The project has been featured in live broadcasts by BBC Solent Radio and online in the Freshwater Blog.

 

3.

And it looks amazing too, creating new ornament in a public space that makes it a better place for people as well as for wildlife!