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Thames Tideway Tunnel super sewer completed

24 points| Brajeshwar | 2 years ago |bbc.com | reply

45 comments

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[+] katdork|2 years ago|reply
>After testing over the summer the super sewer will be handed over to Thames Water, a water company about £15bn in debt and dogged by constant rumours of financial problems. So why should they be trusted to run the super sewer?

>"We have had our challenges. It's absolutely fair to say that." Tessa Fayers, Thames Water's operations director for Thames Valley and Home Counties, told BBC News.

> "But I think one of the things if you go back in our heritage back to the 1800s Thames Water is phenomenal at delivering infrastructure solutions that provide fantastic sanitation services to the city of London."

Throughout their history, their predecessors were not private companies, but from '74 until 89, they were at least a regional water authority. This is a hilarious thing for someone to have said, especially within the corporation.

To go further, from Wikipedia:

> The company has been criticised for paying substantial dividends to shareholders while simultaneously taking out loans, accumulating £14 billion in debts. In June 2023, Thames Water was reported to be close to financial collapse; while it secured £750m from shareholders in July 2023, the company warned it would need a further £2.5bn from investors by 2030.

It's almost like most of their problems are as a result of that privatization, even... wow.

[+] switch007|2 years ago|reply
> Initially expected to cost £4.2bn, the tunnel has ending up costing about £5bn

By modern standards that seems extremely well-costed! What's £800m / 16% these days?

Rivers/sewage is a hot-topic in England at the moment as the water companies are trying to manufacture consent; trying to get bailouts and/or permission to massively raise prices to fix issues they neglected over many years in order to make shareholders happy (yes, water is fully privatised in England, naturally...though I'm not sure if Scotland (where it's publicly owned) is faring any better when it comes to sewage dumping?)

[+] JetSetWilly|2 years ago|reply
Scotland is not faring any better at all. It's just that "sewage in waterways" is not measured in Scotland very much. In England they made the mistake of adding lots of sensors to lots of waterways.
[+] mike_hearn|2 years ago|reply
Note that Ofwat have reduced prices in real terms over time, whilst the population has gone up a lot. So the water companies are doing more with less, which is part of why Thames Water is in so much debt.
[+] kypro|2 years ago|reply
To be honest I think Theo is probably right. This is an issue because rain water isn't being dealt with correctly and they're allowing rainwater to be mixed with sewage – which I believe was the norm in the victorian days.

Perhaps it was more expensive to modernise the sewage system and separate sewage from rain water, but what they done here does not fix the problem it just patches it so it's not a problem for now.

"It's cheaper to let someone else deal with this later" is not a good reason to not do something today. Why should later generations have to deal with this problem? What if they decide its their grandkids problem?

I'm sure there was a long debate on the pros and cons of different approaches here. I'm sure it's just the way the article is written, but either way it's annoying that we seem to lack the ambition to build things that last and that we can hand to our grandkids with pride.

[+] bbatsell|2 years ago|reply
Due to industrialization and cars, stormwater runoff, especially what’s called the first flush, is very polluted. If we had unlimited resources, treating both wastewater and stormwater runoff + strict impervious cover restrictions and on-site storm retention systems would be the best option. The reason a combined sewer isn’t generally preferred now is because the maximum capacity must account for torrential rain, otherwise the system will outflow raw sewage, and a polluted first flush is preferable to raw sewage. The cost to retrofit London’s sewer to be separated would be several orders of magnitude more than upsizing the combined sewer to handle predicted rain events. If they got the capacity right, then it is the best option.
[+] ianburrell|2 years ago|reply
Is it better to fix the problem now or spend decades doing it properly? Consider how much money it would take to dig up every street, add new sewer pipes, and coordinate disconnecting the rainwater pipes.

In Portland, we did similar combined sewer pipe. But they didn't size it to handle the largest rainfall. The sewers still overflow a couple of times a year, but it is much better than dozens of times. Especially since it now only happens in the winter when no one is using the river. It would have cost a lot more to handle peak rainfall. It is already expensive, sewer costs twice as much as water here.

[+] londons_explore|2 years ago|reply
So this tunnel is so huge not because it needs to be huge for the flow needed, but because the tunnel doubles up as a storage reservoir?

Is that really the cheapest way to make a storage reservoir? Wouldn't it have been cheaper to have a regular size pipe, and some big tank at the end?

[+] londons_explore|2 years ago|reply
Part of me suspects it is done this way for political reasons. Nobody wants a sewage reservoir near their house. Everyone is scared of a reservoir potentially bursting and flooding a whole district with sewage.

Whereas if you say "it's a big pipe to take sewage away", nobody can object to that. Everyone wants their sewage taken away.

The fact the pipe is also acting as a reservoir becomes a technical detail.

[+] grahamm|2 years ago|reply
In the southeast of England where would this storage reservoir be?
[+] roughly|2 years ago|reply
> Mr Thomas would rather the money had been spent right across London on projects that stopped rain flowing directly into drains where it mixes with raw sewage.

> "You could use nature to be dealing with this. You could have lots of areas that would soak up the rain rather than rush it off the streets and rush it off the roofs straight into the sewers."

Berkeley's started building bioswales* in several places to better manage stormwater. It makes a lot of sense and is also a big aesthetic improvement - instead of a concrete gully, you've got a nice green patch and some happy plants.

Water management is definitely something we're going to have to get better at. Letting the free water that falls from the sky dump straight into the sewer system is very much a mid-20th-century everything's-infinite-why-worry type approach.

* https://en.wikipedia.org/wiki/Bioswale

[+] barbazoo|2 years ago|reply
> Raw sewage under normal conditions goes to wastewater treatment plants but currently, even a small amount of drizzle in London can overwhelm the network, triggering overflows into the Thames.

Can someone define what's meant here by "raw sewage" please? Are we talking about wastewater from toilets?

[+] wongarsu|2 years ago|reply
Wastewater from toilets, showers, sinks etc watered down by rainwater. But the waste from toilets is what's causing the problems.
[+] mike_hearn|2 years ago|reply
London has one of the earliest sewer systems, and it predates the practice of separating storm drains from effluent drains. Normally the sewers drain through pipes to the water treatment works, but if there's too much rain then the system becomes full and it drains into the Thames to avoid flooding streets and buildings. The new pipe will fix that.
[+] lenerdenator|2 years ago|reply
Toilets, showers, sinks, storm drains, and last but certainly the most severe, the supporters section of Millwall's Den.
[+] londons_explore|2 years ago|reply
Notable that even when this project is complete, there will still be tens of thousands of toilets that still drain into the river.

I think I'd almost prefer houses in Britain to not have toilets at all (require the use of portaloos) than to have toilets that drain into the river.

[+] TylerE|2 years ago|reply
Where do you think all the fish and other animals that Live in the river poop? It’s already unsanitary
[+] robotnikman|2 years ago|reply
Reminds me of the Chicago Deep Tunnel project, expected to fully operational around 2029

https://en.wikipedia.org/wiki/Tunnel_and_Reservoir_Plan

[+] jauntywundrkind|2 years ago|reply
DC just wrapped up our North East Boundary Tunnel project. 23 foot diameter pipe connecting combined runoff system to existing water treatment system. https://www.dcwater.com/projects/northeast-boundary-tunnel-p...

Next up the Potomac River Tunnel in the northwest, a 19 foot 6.5 mile pipe. https://www.dcwater.com/projects/potomac-river-tunnel-projec...

I forget the exact backstory but the EPA got some kind of judgement I guess in 2005 that we couldn't let the combined sewer run off overflow run into the river. This has been our response to that. Work was underway in NEbut took till 2016 to figure out the whole plan, https://www.dcwater.com/about-dc-water/media/news/dc-agreeme...

DC's tunnels are "only" 100ft down. These Chicago tunnels seem much deeper! We also don't seem to have the vast reservoirs Chicago is adding; our tunnels are our storage.

[+] black_puppydog|2 years ago|reply
That title photo could be the opening scene of a very icky action movie. :)
[+] krisoft|2 years ago|reply
I'm very confused by that photo. The description says "The tunnel is wide enough to fit three buses side by side." But either the worker standing in the tunnel is huuuge, or that tunnel clearly can't fit three buses side by side.

Maybe what went wrong is that they read the internal diameter of the tunnel (7.2m) and compared with the width of a bus (~2.5m for a New Routemaster) and forgot that busses are not 2 dimensional line segments.

[+] itsanaccount|2 years ago|reply
I just want to share the change in mindset that can fix this: Water is life. Water when it falls on land you control is precious. You, plants, animals, everything needs that water. Keep it, use it, store it for later, and then when its helped you and the land only then send it on its way.

And if you're worried about mosquitos that what underground reservoirs and BTI is for. https://en.wikipedia.org/wiki/Bacillus_thuringiensis_israele...

But really, rain barrels, storage tanks, cisterns, rain gardens, permeable concrete, tiny ponds. Rain is a blessing you don't appreciate until you don't have it, and we should do more to deal with its destructive effects than just drain it to somewhere else.

Edit: I love these, they're pits in the clay filled with organic soil. https://www.thefoodscaper.com/blog/how-to-manage-rainwater-r...

[+] louthy|2 years ago|reply
Not sure how your comment related to a new sewer? If you're suggesting that we need to stop the water somehow getting into the sewers in the first place, I think that's unlikely to happen by people putting out a few rain barrels.

London's aging sewer network (an engineering marvel at the time it was built) has needed this upgrade for a while. For the dual reason of population growth but also the vast amount of water that we get when it rains is causing overflows into the river.

One thing Britain isn't short of is water; and it looks likely to get worse with the adverse weather events that are seemingly more frequent now. Most predications are that Britain will get wetter because of climate change.

[1] https://en.wikipedia.org/wiki/London_sewer_system