The dam at Toddbrook. Source: Twitter
By now most of the world will have read of the calamity at Toddbrook Reservoir above Whaley Bridge and seen the huge efforts to prevent the town becoming inundated by any collapse of the dam.
Toddbrook reservoir is in Derbyshire and was built in 1838 for the Peak Forest Canal. It is one of the higher canal reservoirs in the country, and there is a simple reason for this, the canals it feeds are some of the UK’s highest canals at an elevation of 518 feet/157m (barring the summit level on the Huddersfield Narrow Canal at 644 feet/196m and Titford at 511 feet/155m elevation.)
It seems at the moment the dam could be saved, which is good. But can it be used? That is another question. I don’t think it can be reused – not without a good case being made for safety and necessity of use.
The damage to Toddbrook Reservoir. Source: Twitter
I somehow do not think so. Contrary to what a lot of people assumed on social media (and even on the news) the canal was built first (and the reservoir too) and the town grew up by the reservoir, because it became a hot spot in terms of industry and transshipment between the canal and the Cromford and High Peak Railway.
It will probably turn out that the risk to life is so great Canal & River Trust will have to close it & use its other reservoirs eg Boseley and Sutton (which are remote) & use back pumping to keep the canals topped up.
The RAF Chinook being used to plug the breach in the dam. Source: Twitter
It isnt just that. There will be the enormous cost of repairing the reservoir and making it ultra-safe for Whaley Bridge and the towns and communities that have grown up in the Goyt Valley further down. These communities are important because they are dormitory towns essential to Manchester and are connected by railway.
In recent years they have even built houses right along the bottom of the reservoir which shows just how large the town has become and how people have always though their homes would be safe. These days no-one would be allowed to build a dam of this size and scale above a town. There are very likely going to have to be alternatives.
Coombs reservoir. Source: Twitter
Coombs reservoir which also feeds the canal system is further up the valley but its not so high nor so large and it can still be used. Boseley is a huge reservoir sited on the Macclesfield Canal and that can be very easily used to feed the Peak Forest Canal as well as another smaller one at Sutton.
In the event it may turn out that Canal and River Trust would have to install back pumping on both its canals (Macclesfield & Peak Forest) to assist in times of low water and possibly also source water from other locations.
Recent picture of Boseley on the Macclesfield Canal. Source: Twitter
Another issue to bear is Canal and River Trust is a charity and I think this at Whaley Bridge is going to be somehow way beyond the means and resources of this charity entrusted to look after the country’s waterways and reservoirs.
The canals hereabouts are considerably important because they supply water to the ones lower down such as the Trent and Mersey, Ashton and Bridgewater canals.
Although there are other sources such as those coming down the Huddersfield Narrow Canal these aren’t beneficial to the Macclesfield/Peak Forest canals unless water is back-pumped.
I may add updates to this page later if they are deemed necessary.
UPDATE: The reservoir seems okay, I said that quite a few hours ago on my Twitter at that point it was clear it wouldn’t collapse. The hole in the dam has been largely plugged. Now there’s further work to be done and of course investigations will be necessary.
Some of the more expert opinions think the reservoir will be repaired fully and put back into use. I’m not so sure, but then I’m no engineer or qualified of any sort. I just think the residents of the town wouldn’t want the reservoir back in use after all this trouble – would they even feel safe? That is why I wrote this post originally as it was quite clear there were alternatives to having the reservoir reinstated.
UPDATE SATURDAY 3RD AUGUST: Loads of stuff on social media with many even questioning why a dam has been built almost right in the centre of a town (its a complicated sort of history that!) But there has also been more and more people thinking its not a good idea to continue to have a dam at this location.
Even professionals have chipped in with their thoughts on the matter and concluded the reservoir shouldn’t be here. The new PM, Boris Johnson, was reported as saying the dam should be rebuilt.
Clearly there are many opinions as to how the matter should proceed. The first of course to be dealt with as most will know, is to get the reservoir and its dam made completely safe before the next lot of rainfall.
Then there will be investigations, surveys, enquiries, with the opportunity to blame the reservoir’s management, frequency of inspections and so on. In the longer term certainly a decision will be made whether to keep the reservoir and rebuild its dam or decommission it completely. That wont happen for quite a few months though.