Lack of headroom due to a build up of bed materials, and the potential for scour damage during flood conditions required flood elevation works for our Client, Calderdale Metropolitan Borough Council.

Guerning Dog Road Bridge is located 0.5 miles west of Todmorden, Calderdale, West Yorkshire, and carries Knowlwood Road at a junction with Rochdale Road over the River Calder.  Due to the susceptibility of the River Calder to respond quickly to rainfall and consequently rise in river level, it was imperative that the weather conditions were checked and monitored prior to and during any activities where personnel are working in the watercourse.

To allow semi-dry access below the bridge structure, the river was flumed through two 600mm diameter twin wall pipes each 35m in length. A dam of bulk bags of sand was then constructed upstream and downstream of the bridge to diver the flow through the flume pipes.

Once the river flows were diverted, the river bed materials required reducing down to formation level beneath the bridge and for 6m upstream and downstream of the structure to allow placement of the proserve scour protection Mattresses.

2 x 6” submersible pumps were used to dewater the bunded areas to allow excavation of the bed materials. Due to the high flood protection walls on either side of the river, it was necessary to lower the 3t excavator and micro excavator into the river using a 10 hydraulic crawler crane. Two-way temporary traffic management was put in place to achieve this.

120t of mobile bed materials were moved from below the bridge to increase the headroom and achieve the formation levels for the design. Care had to be taken not to undermine the bridge foundations or the footings of the adjacent retaining walls.

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