Toddbrook Reservoir, near Whaley Bridge in the Peak District, supplies water to the Peak Forest and Macclesfield canals. These waterways are hugely popular for boating, angling, walking and cycling, and form part of the Cheshire Cruising Ring.
Following intense heavy rainfall at the end of July 2019, several concrete panels on the Toddbrook dam spillway became dislodged. Around 1,500 residents of Whaley Bridge were evacuated from their homes for six nights as a safety precaution. Trust staff and volunteers worked around the clock with the local emergency services, including Derbyshire Fire & Rescue, Derbyshire Police and the Environment Agency, to stabilise the dam wall.
Over a billion litres of water were pumped from the reservoir during this emergency phase and water levels continue to remain nearly empty while the dam is repaired. This is likely to take several years.
Gillian Renshaw is the Trust’s dedicated local community engagement manager during the project. Come and meet her at one of the weekly drop-in surgeries.
Where: Transhipment Warehouse, Whaley Bridge
When: Wednesdays, 10.00pm-3.00pm
If you need to get in touch, please email: email@example.com.
|Construction:||Built in 1830s. Opened in 1840 as a feeder for the Peak Forest and Macclesfield canals|
|Volume:||1,238 megalitres – equivalent to 495 Olympic-sized swimming pools|
|Dam wall height:||23.8m|
|Environmental status:||Site of Special Scientific Interest (SSSI)|
Yes. The reservoir is drained to near empty while investigations and a major repair/reconstruction programme are carried out. Water levels are being continuously monitored and 11 high powered pumps are in place to keep the reservoir near empty.
Damaged areas of the dam wall have been secured with emergency repairs and the wall will be further modified over the next few months to make it even safer.
Between Thursday 1 August and the following Wednesday, over one billion litres of water were pumped out of the reservoir into the River Goyt – working with the Environment Agency to avoid downstream flooding. This lowered water levels in the reservoir by over ten metres.
An RAF Chinook helicopter dropped over 500 one tonne bags of aggregate onto the damaged section of spillway to reinforce the structure and grout was poured around the bags to bind them in order to further strengthen the dam.
At the same time, work to divert the water feeds into the reservoir took place to prevent it filling back up.
It is still too early to confirm the exact cause of the damage to the dam’s spillway. However we've commissioned an independent dam expert to look at what happened. DEFRA has also commissioned an independent Government Review, which is due to report back by the end of 2019. Both these reports will help to inform the plan for repairing the dam.
We estimate that there were about 30,000 fish (about 5 tonnes) in the reservoir at the start of the dam emergency in August. As the water levels were reduced, we carried out an emergency fish rescue as part of the main drawdown in early August and later in October completed a second major fish rescue to move as many of the remaining fish as possible. A further small fish rescue is planned for December.
Autumn and winter are more suitable times of year for moving large quantities of fish because the weather is cooler and better for the health of the fish. Coarse fish, such as bream, roach, perch and pike, have been captured in large nets by the Trust’s fish specialists and then transported to another Trust reservoir, Upper Bittell Reservoir, near Birmingham.
Upper Bittell Reservoir was drained and then refilled after maintenance works two years ago and is in a good position to re-home large numbers of fish.
The Canal & River Trust manages 72 reservoirs and has an experienced team of specialist reservoir engineers. These engineers are appointed into the role by the Secretary of State for the Environment on the advice of the Institution of Civil Engineers. Their inspections meet the industry’s highest standards.
As well as visual inspections twice a week by Trust operatives, our reservoirs are rigorously inspected twice each year by our reservoir engineers and also undergo detailed ten yearly inspections by an independent government-appointed Inspecting Engineer. These inspections consider the best industry-wide knowledge regarding dam construction and stability. We prioritise spending money on reservoirs wherever a need for maintenance work and/or repairs is identified.
The dam is visually inspected twice weekly by Canal & River Trust operatives and rigorously inspected twice each year by our skilled reservoir engineers. It also undergoes a detailed ten yearly inspection by an independent Inspecting Engineer – the last one at Toddbrook took place in November 2018.
The standards by which our structures are measured and assessed are constantly being reviewed. This would include any learning from the impact of changing weather conditions.
The exact nature of rebuild or repair of the dam will be determined following the inquiry into the cause of damage and using the latest design and construction techniques.
The lights are needed to monitor water level gauges overnight. Following feedback from local residents we have made modifications to minimise disruption to local residents.
We have closed the footpath while the dam wall and reservoir repair project is being planned and delivered. If there is a chance to re-open it sooner, we will.
The depth of the reservoir is less than when it was constructed due to siltation and now is around 14m at its lowest point. We do not have any plans to make the reservoir deeper or undertake silt removal from the bed of the reservoir.
Yes, all the surrounding land owned by the Canal & River Trust will be re-opened once the project has been completed. We are not able to confirm plans for land owned by third parties.
The current capacity of the reservoir supports the Peak Forest and Macclesfield canals. A reduction in its size would make it much harder to successfully operate these two canals.
The reservoir is already designated a Site of Special Scientific Interest and we need the current capacity to feed the Peak Forest and Macclesfield canals.
It's too early to say what caused the collapse. The Canal & River Trust has commissioned an independent expert to investigate the causes. DEFRA has also appointed its own independent Government Review. Both are due to report back by the end of the year.
Following completion of the review, we'll be better placed to evaluate all our monitoring systems for the reservoir in the future.
Once the review is complete, we'll be in a better place to plan the most appropriate way to repair the dam wall. This may mean making changes to its construction.
Works to the decking on the bridge have been reinforced to support the construction operations at the site. We'll examine the bridge structure as part of the general dam repair/reconstruction project and make sure it's in good condition for the future.
We've been liaising with local schools to arrange special talks and visits. Nationally we run an Explorers programme for young people and we will hope to link into this with future activities.
At depth, we don't anticipate the clay core will dry out significantly. When we come to refill the reservoir, this will be done in a controlled fashion to give the dam time to rehydrate. All works will be completed in consultation with reservoir experts.
Last date edited: 12 November 2019