Mott MacDonald Bentley will raise the spillway walls and replace the steep section (towards the middle of the spillway) with a straight slope to ensure flood waters are contained within the channel.
Designed by Thomas Hawksley, the stone spillway was completed in 1906. It controls the flow of water from Butterley reservoir, safely ensuring it does not overtop and damage or erode the embankment.
A previous inspection of the spillway by an independent panel engineer had highlighted the need to adapt the spillway to ensure it continues to meet with legislation and the Reservoirs Act 1975, in particular.
Yorkshire Water project manager Lee Laherty said: “We know that the spillway is a much-loved local landmark and we’ve worked hard to design a solution that’s sympathetic to the local surroundings, whilst ensuring it meets legal requirements.
“We are going to replicate the existing small steps within the spillway, retain two thirds of the existing spillway walls and re-use coping stones where possible. We’ll clad the raised walls with natural sandstone and hope to retain the majority of existing keystones.”
The engineering project will take until the end of 2017 to complete. Some of the local footpaths around the reservoir need to be temporarily diverted so the work can be carried out safely.
Colne Valley MP Jason McCartney said: “I’ve been urging Yorkshire Water to engage with the local community and interest groups for a number of years now regarding this important project. I’m fully aware of the sensitivity around the impact to the spillway. I hope they continue to listen to feedback and support local initiatives whilst they’re working in the area.”
A version of this story first appeared on WWTonline.