just had an emergency related to the spillway of a dam. BBC – Whaley Bridge: How well was the dam maintained?
On 1 August 2019, water poured over the auxiliary spillway of the Toddbrook Reservoir, in Whaley Bridge, Derbyshire, UK. This was in the middle of a torrential downpour. (They got ½ month’s rainfall in 1 day.) The concrete spillway failed in fairly short order, and the earth, of a mostly earthen dam, began to erode. Evacuations were ordered. (This has reminded several people of the Oroville Dam near-disaster of 2017.)
There is a great picture of the spillway at the BBC article above that shows plants growing through the concrete, that would seem to indicate that the spillway was not maintained the way it should have been. Despite that, its annual inspections have rated the dam as “fine.” But then the dam at Oroville was inspected, and it was rated as “fine” or something to that effect, right before it failed spectacularly. (At least no one died in either event.)
The Canal and River Trust said the annual inspection of Toddbrook Reservoir in November was “absolutely fine”.
This coincided with an independent inspection taking place every 10 years, and the trust said this was fine too.
Both Oroville and Toddbrook dams were inspected. In both cases they were deemed in fine shape. Right before their spillways failed, nearly undermining the integrity of the dams. Seems like the inspections are not worth that much.
Background on the Toddbrook reservoir can be found at the Wiki.
In many ways the UK is worse off when it comes to aging infrastructure than the US. While they didn’t go in for grand designs like the Oroville dam, they have quite a few smaller ones. And they are old.
[Dr Panagiotis Michalis, who has been researching dams since 2010,] believes dams are a “ticking bomb” because of their ageing infrastructure and thinks incidents like the one at Whaley Bridge will become more common.
“In the UK the majority of the dams are more than 100 years old. That means they’ve exceeded their design lifespan,” he said.
You can’t ignore a major engineering work like a dam, that has exceeded its designed life, without catastrophic consequences. And yet it seems that is exactly what we are doing. Whaley Bridge dam collapse is a wake-up call: Concrete infrastructure demands maintenance.
At almost 50 years old, the thin grey line of concrete protecting the town of Whaley Bridge from the reservoir just a mile away has reached the end of its life. To fail to invest in and maintain these structures is reckless.
In the case of Toddbrook Reservoir, images of the damaged spillway may point to lack of enough maintenance. Drone footage shot by Miles Haslam in 2016 shows plants and grass growing on the surface of the spillway. This could mean the concrete surface may have already been cracked, or even that the foundation of the concrete spillway had been undermined, allowing plant life to grow. All this should be subject to a future investigation.
There is drone footage of the damn, at that 2nd link above, from 2016 that clearly shows the vegetation growing through the concrete.
And, drawing on all he learned from covering the Oroville near-disaster, Juan Browne, of Blancliro, also has coverage of the Whaley Bridge dam.
In both the cases of Toddbrook/Whaley Bridge and Oroville we avoided loss-of-life, but these are not the only two dams with problems. Trusting to luck, when people could die is certainly reckless.