Rydings Reservoir scheme nominated in NW Engineering ‘Oscars’

Rydings Reservoir before the civil engineering work

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A scheme to secure a Rochdale reservoir against the risk of flooding has been nominated for an award by the Institution of Civil Engineers North West.

Rydings Reservoir is located on Buckley Brook behind an earthworks dam which is of an unknown construction and age. The risk of structural failure and subsequent flooding led the Environment Agency to invest nearly £200k to resolve the problem.

The project focused on reducing the water pressure on the dam by building a new spillway at a lower level, minimising the volume of water retained. The new spillway successfully lowered impounded water levels, creating additional capacity within the reservoir by restricting flows.

A new footbridge across the top of the new spillway headwall provided a safe access route across the dam, while previously walkers had entered the old spillway to cross to the dam.

The new spillway now returns water to the existing spillway downstream over a series of side spill weirs. This prevents damage to the bed and the retaining wall which forms the far bank. Additionally, the works have enabled upland wetland and flood plain to be reinstated, providing habitat for flora and fauna. The project has provided a more stable water edge habitat, with planting scheduled next year to further enhance this feature.

ICE North West Regional Director Alan Butler said the scheme had delivered a cost effective structure which will reduce the risk of flooding.

“It has also brought additional benefits both to wildlife habitat and the safety of walkers, while at the same time retaining the industrial heritage features such as the dam and its inlet tower. The scheme permits flood storage within the reservoir, with water flowing over the original spillway in the event of flooding,” said Mr Butler.

Material reclaimed during construction of the new spillway was reused to in-fill a potentially hazardous sink hole, while the remainder was used for landscaping around the new structure and existing dam. The result was a reduction in lorry movements and no material was sent to landfill.

The project was commissioned by the Environment Agency, designed by Atkins and undertaken by CT Construction. The submission will now be judged with other regional Small Project Award schemes at a gala awards night to be held at Chester Racecourse on Friday 7 February 2014.