Client: Dawnus Construction Ltd Duration: 6 Weeks Value: £59,000

Kaymac were commissioned by Dawnus construction Ltd to install a controlled water flow system to sheet pile cofferdam.

Located on the river Taff, the Radyr Weir hydro scheme comprises 2 x 200 kW Archimedes screw turbines, each roughly 3.5 m in diameter, with a total installed capacity of 400 kW. Situated on the eastern edge of the weir, the scheme exploits a drop in height (head) of roughly 3.5 m and a mean flow of roughly 22 cubic metres per second generating electricity.  Kaymac were commissioned by Dawnus to install a controlled water flow system to sheet pile cofferdam.  The sheet pile cofferdam was installed prior to Kaymac’s team arrival on site creating a dry working area for Dawnus to construct the Hydroelectric turbines. At stage one Kaymac welded two penstocks onto sheet pile cofferdam and cut behind pile to allow water flow at the required pressure through the hydroelectric turbine system as and when required during the testing of the screws.

 Pilles and penstocks

When the testing of the turbine screws were complete, a team of Kaymac divers were required for the stage two pile removal works. To remove the piles Kaymac divers cut the sheet piles underwater at bed level, and used dredging equipment carried  out  through  a  joint  effort  between  Dawnus  (using  land  based excavators) and Kaymac (using suitably sized Hydrainer pumps and air lifts) to dredge the river bed material away from the piles to enable them to be removed with crane and lifting personnel in accordance with the lift plan.   

Hydroelectric Turbines

 One of the challenges with this project is that the Radyr Weir site had no access to the river, therefore access needed to be by man riding baskets. Kaymac operatives often work in these conditions and are experienced in doing so. 

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