£12m repair plan unveiled for Toddbrook Reservoir
A PERMANENT repair plan has been announced for restoring Toddbrook Reservoir in Whaley Bridge, Derbyshire, following the damage to the slipway in summer 2019.
The Canal & River Trust is planning to build a new side channel weir, ‘tumble bay’, spillway channel and stilling basin on the northern sailing club side of the dam, at an estimated cost of between £12 million and £16 million. The auxiliary spillway will be decommissioned and the dam slope grassed.
Daniel Greenhalgh, Canal & River Trust North West director, said: “Repairing the reservoir is a huge engineering challenge and public safety is our top priority. The permanent repair design has been shaped by local feedback and guided by modern engineering best practice.”
Subject to planning permission, work is likely to start at the end of 2021 and will take about two years to complete. The reservoir, which supplies water to the Peak Forest and Macclesfield canals, has been out of action and near empty of water since the spillway was damaged.
Ahead of the permanent repair, the trust and its contractors, Kier, have carried out a major project to make safe the damaged spillway and add a protective waterproof nib to the dam crest.
Once the new repairs are completed, the concrete and dropped bags of stone will be removed and the area will be grassed over.
The repair plans have been drawn up by the Canal & River Trust’s project team, working with specialist engineering design consultants Arup following extensive technical investigations and design work.
Local input
Importantly, there has been a lot of input through public consultation with the residents of Whaley Bridge. The town was threatened by flooding when the reservoir – a well-used and appreciated facility for sailing, walking, open water swimming and angling – overtopped the spillway in 2019.
Daniel commented: “It was a nice surprise to find out how many dam engineers, both working and retired, live within Whaley Bridge and the local area. They have taken an interest, and provided great input and ideas into the consultations.”
Two options were put forward from an initial 13 potential proposals considered by the design team, which continues to develop the details of proposals to ensure the most effective design solution is adopted.
A second public consultation into the proposed plan will be organised for later in the spring, probably online, in advance of a planning application to High Peak Borough Council this summer.
Daniel continued: “The new spillway will unfortunately require the relocation of the sailing club’s clubhouse and slipway. We are committed to working with them to ensure we provide suitable replacement buildings, boat storage and slipway to support their continued use and enjoyment of the reservoir once the project is complete.”
At the moment the club is sailing on the waters of the Errwood Sailing Club, a few miles away towards Buxton.
Play area move
“The proposed work will also require some changes to the northern area of the park,” explained Daniel. “The play area will have to be repositioned, and we will carry out landscaping works to ensure that, when finished, the park remains an enjoyable and open public space.
“We are working to develop our plans to ensure this happens as sensitively as possible.
“During construction, part of the park will unfortunately have to be closed, but we hope to be able to move some of the play equipment to an alternative location so it can continue to be available.
“These changes are necessary to construct the new side channel weir, ‘tumble bay’, spillway channel and stilling basin in an optimum alignment, both within the landscape and for reservoir safety. The stilling basin will then connect with the River Goyt at the existing location via a channel through the park.
“The use of a side channel weir allows us to connect the existing reservoir by wash into the top of the tumble bay, which will mean water flows down the spillway at all times.
“We were guided in this design modification by public feedback, indicating that a continuous flow of water down the spillway was preferable to having a predominantly dry channel.”
Construction work on the dam will be followed by works to the inlet cascade at the far end of the reservoir to increase its resilience to high flows from the Todd Brook stream.
It is hoped to reopen the reservoir to the public in early 2024 and once again feed water into the upper Peak Forest Canal.
Meanwhile, work continues to re-establish flow through a feeder of water into the canal from Coombs reservoir. Due to some challenging locations under buildings in the town, the release of water from Coombs is currently into the river Goyt and then pumped out into the canal at the Whaley Bridge basin.
High-volume pumps will remain in the reservoir to manage water levels until the end of the project.