Knottingley Hydropower scheme, Brotherton Weir, River Aire, Knottingley, West Yorkshire.

Knottingley Hydropower scheme is the largest hydropower station to be built in England since the turn of the century. JNP were commissioned to provide structural and civil engineering services on the project.

The scheme consists of dual Kaplan turbines 2m in diameter which are estimated to produce 3 million kilowatt-hours per annum, equivalent to the consumption of 1000 households.

Sheet piles were installed to create a cofferdam alongside Brotherton weir, and extensive temporary works propping allowed excavation and construction of the reinforced concrete channel within the cofferdam. Once the turbines were installed and the structure complete, the cofferdam was flooded and the inlet and outlet sheet piles burned off.

Brotherton weir, at 2.6m high presents one of the largest obstructions to the free passage of salmon and trout from the Humber Estuary to the upper reaches of the river system. A 4.6m wide Larinier fish pass was constructed as part of the scheme, which will allows safe passage of migratory fish upstream to spawn. Eel and Lamprey are also accommodated with the separate eel pass which is attached to the existing weir.

Fish travelling downstream are protected from the turbine by the provision of the custom built 12mm inlet screen, which has an automatic screen cleaning machine to keep the screen clear of any debris and ensure optimum flows for electricity generation. In addition, the outlet screen prevents larger, more powerful fish from travelling up into the turbine outlet.