Diglis Penstocks – Unlocking the Severn
Work on the Diglis Fish Pass in Worcester began in September 2019. The finished structure will enable twaite shad, a member the of herring family, to once again migrate freely upstream to spawn. This is one of four fish passes on the River Severn being constructed as part of Unlocking the Severn – an ambitious river conservation project led by Canal & River Trust in partnership with Severn Rivers Trust, the Environment Agency and Natural England. Kier is the lead delivery partner for these fish pass construction works.
Taking the form of a series of ascending pools that allows the fish to swim from a lower level downstream to a higher level above the man-made weir. The pass also features control structures at the upstream exit to allow for future maintenance of the channel.
Aquatic Control Engineering Ltd (ACE) is proud to be working on the Unlocking the Severn project, providing the control structures.
At this site, ACE installed four penstocks. Two are used to control the levels within the fish pass. These penstocks are 2.5m x 1.5m with a 5.4m frame height, operated by hand held spindle drivers. There are two additional penstocks installed on each side of the main fish pass. These are used to create an attraction flow to encourage fish into the pass.
One of the unique features of this project was the need for four side sealing penstocks while still being mounted in an open channel. Ordinarily, this would require the construction of a headwall to provide support for the top sealing face. ACE supplied a bespoke penstock with a unique back plate and support design. This enables the four-side sealing required.
Additional savings made by ACE on this project were their unique flush invert penstock design, which removes the need for extra formwork. Most penstock suppliers require a slot to be cut out to enable mounting. ACE’s design means there is no need for formwork, grouting, waiting etc, just simply secure with chemical anchors.
ACE would like to thank everyone involved for getting us to work on this fantastic project. Find out more at www.unlockingthesevern.co.uk