Restoration of the existing culvert that feeds the turbine chamber
Key design criteria ensured the VETT unit was integrated into the existing infrastructure of the Grade II listed mill, preserving the historic and leisure amenity of the site.
The mill is home to pub and restaurant The River Mill, and the VETT was installed under the pub's outside decking, out of sight.
The scheme is designed to be installed and operated in a way that protects the juvenile coarse fish nursery areas in the marina and mill pond and to accommodate eel passage, as specified in stakeholder discussions with the Environment Agency.
Previous live trials already showcased VETT’s safe fish passage credentials. In addition, careful eel passage design opened up this stretch of water to migrating eels.
The River Great Ouse is a navigable stretch of river which is also prone to flooding. It was important to coordinate the management of water levels by the Environment Agency’s sluice at Eynesbury Weir with VerdErg's hydro scheme.
A control system and an operating approach agreed with the Environment Agency ensures that the hydrological parameters can be real-time monitored to achieve this.
After the feasibility and detailed design phase in 2017, all regulatory consents were received by January 2018 and Greenford Ltd was appointed to undertake the civil construction phase of the build.
Video: installation the VETT
4,000 litres of water are flowing through the VerdErg VETT pipework per second.
The VETT is made out of glass reinforced plastic (GRP) and is relatively lightweight.
Originally it was envisaged to assemble the pipe sections in situ in a dry cofferdam. After review, the contractor assembled the pipe on site first and lifted it into place in one long piece.
Once the VETT was installed and final civil works completed the turbine with secondary pipe was installed.
The whole system is installed underneath decking used by customers of the adjacent pub.
In order to install the turbine, a section of the decking was lifted out, the turbine dropped in, and the lid closed again.
Video: the VETT's unique hydro system handles 4,000 litres of water per sound with a turbine that is only 400 mm in diameter, and is completely invisible and silent.