Thames Tideway Tunnel super sewer completed(bbc.com)
bbc.com
Thames Tideway Tunnel super sewer completed
https://www.bbc.com/news/science-environment-68464798
10 comments
> 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?)
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?)
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.
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.
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.
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.
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.
Makes sense. Cheers for adding some more context.
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.
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.
Hi Ian!
Portland has also been working on the “next steps” pointed out in this article. Street bioswales provide absorption and holding capacity. Downspout disconnection programs and new build codes drain rooftop rain locally on the property or out to the street instead of directly in to the sewers.
I think we have an easier time due to our lower density. Most lots have decent amount of exposed ground for rain infiltration, and the area has well draining soil. Tougher for cities more tight and built up. I think Seattle codified water management before the latest building boom so hopefully they will do alright too!
https://www.portland.gov/bes/stormwater/about-green-streets
Portland has also been working on the “next steps” pointed out in this article. Street bioswales provide absorption and holding capacity. Downspout disconnection programs and new build codes drain rooftop rain locally on the property or out to the street instead of directly in to the sewers.
I think we have an easier time due to our lower density. Most lots have decent amount of exposed ground for rain infiltration, and the area has well draining soil. Tougher for cities more tight and built up. I think Seattle codified water management before the latest building boom so hopefully they will do alright too!
https://www.portland.gov/bes/stormwater/about-green-streets
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?
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?
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.
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.
In the southeast of England where would this storage reservoir be?
It’s been over 50 years and we still haven’t built the only proposed reservoir in Kent at Broad Oak near Canterbury. We are useless at getting things done in the uk. That a third Blackwell Tunnel is being built is incredible.
It's raw sewage, so probably not on the surface.
You'd dig up a few acres of park and put it underneath.
You'd dig up a few acres of park and put it underneath.
> 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
> "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
> 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?
Can someone define what's meant here by "raw sewage" please? Are we talking about wastewater from toilets?
Yes.
Unrefined brown sauce.
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.
Apparently, the first official inquiry into London's sewerage recommended a separated system, but Bazalgette prevailed and his design was a combined system. Other British cities, and other cities round the world, copied this design.
https://news.sky.com/story/down-the-drain-what-went-wrong-wi...
https://news.sky.com/story/down-the-drain-what-went-wrong-wi...
Seattle also has this problem and our sewer network is more modern. We are also building a storage tunnel!
I believe this might be the Ship Canal Water Project? https://www.seattle.gov/utilities/neighborhood-projects/ship...
I'll give you one guess if I'm a local or not!
I'll give you one guess if I'm a local or not!
Your username gives you away!
Realistically, if your sewerage system is from before the mid-20th century, you'll usually have this problem.
Wastewater from toilets, showers, sinks etc watered down by rainwater. But the waste from toilets is what's causing the problems.
I hope they'll do the Olympic swimming events upstream of that then.
It seems Paris is well on its way to cancel the swimming events in the Seine this summer, so it's not exactly an isolated issue
Toilets, showers, sinks, storm drains, and last but certainly the most severe, the supporters section of Millwall's Den.
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.
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.
Where do you think all the fish and other animals that Live in the river poop? It’s already unsanitary
Not even comparable. The amount the water companies have been draining into rivers and the sea around the UK is embarrassing, especially when they still pay out dividends to share holders while claiming they need more money for investment in the infrastructure to deal with the sewage spills, while barely being able to service their loan obligations.
Why? It's not potable water. It will inevitably be full of all kinds of pollution. Why is one thing a bridge to far for you?
Reminds me of the Chicago Deep Tunnel project, expected to fully operational around 2029
https://en.wikipedia.org/wiki/Tunnel_and_Reservoir_Plan
https://en.wikipedia.org/wiki/Tunnel_and_Reservoir_Plan
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.
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.
That title photo could be the opening scene of a very icky action movie. :)
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.
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.
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...
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...
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
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
Agree. To further complicate the picture, most of London is very flat and lies between -3 and 9m of sea level[1] and we (are extremely lucky to) have a massive tidal river running smack bang through the middle of the city. We already have a massive tidal barrier that protects the city from flooding at high tides [2].
For people who don't understand the problem the tideway addresses, it's not like we just pump sewage into the river, it's that when there is a lot of rain the sewers can flood with runoff and can flood into the river.
[1] https://en-gb.topographic-map.com/map-kffs8/London/?center=5...
[2] Which is an engineering marvel and quite beautiful in my opinion. A boat trip up to see it is well worthwhile during a visit for people who want to do things that are a little unusual https://en.wikipedia.org/wiki/Thames_Barrier
For people who don't understand the problem the tideway addresses, it's not like we just pump sewage into the river, it's that when there is a lot of rain the sewers can flood with runoff and can flood into the river.
[1] https://en-gb.topographic-map.com/map-kffs8/London/?center=5...
[2] Which is an engineering marvel and quite beautiful in my opinion. A boat trip up to see it is well worthwhile during a visit for people who want to do things that are a little unusual https://en.wikipedia.org/wiki/Thames_Barrier
> One thing Britain isn't short of is water
Britain as a whole gets quite a lot of rain but it is not equally distributed [0]. Basically the western side and mountainous areas get the most (>2000mm per year) while the south east gets much less (600-700 mm per year). There is no 'national grid' for water (mechanisms for bulk movement from the wet to the dry areas). Even though the population has increased a lot there hasn't been a significant new reservoir built for decades. The south east regularly has hosepipe bans in the summer. Vast amounts are lost through leakage from the very old infrastructure, while the relatively newly privatised water companies have taken on massive debts in the process of generating shareholder value, rather than fixing things.
[0] https://www.metoffice.gov.uk/weather/learn-about/weather/typ...
Britain as a whole gets quite a lot of rain but it is not equally distributed [0]. Basically the western side and mountainous areas get the most (>2000mm per year) while the south east gets much less (600-700 mm per year). There is no 'national grid' for water (mechanisms for bulk movement from the wet to the dry areas). Even though the population has increased a lot there hasn't been a significant new reservoir built for decades. The south east regularly has hosepipe bans in the summer. Vast amounts are lost through leakage from the very old infrastructure, while the relatively newly privatised water companies have taken on massive debts in the process of generating shareholder value, rather than fixing things.
[0] https://www.metoffice.gov.uk/weather/learn-about/weather/typ...
> One thing Britain isn't short of is water
Exact same thing is happening in the midwest of the US, where the green belt is heading east and dropping more water in less time on less area.
Its not just "a few rain barrels" its literally every single property and every single development being upgraded and designed to capture and store water and let it seep into the soil before overflowing into the sewer.
Not only does it make a better place to live as you generally need plants to use that water, but its the only way to capture it at scale. I live in a swamp, and right now is the time of what I call "the big slurp" where all the plants turn green, and the high water from winter that has the water table at ground level will drop 6 inches as every plant turns into a straw. It happens over 3-4 days and its wild to see.
A bigger and bigger sewer is the "just one more lane" to fix traffic congestion. It doesn't work, definitely not as a singular solution. https://www.theguardian.com/world/2017/dec/28/chinas-sponge-...
Exact same thing is happening in the midwest of the US, where the green belt is heading east and dropping more water in less time on less area.
Its not just "a few rain barrels" its literally every single property and every single development being upgraded and designed to capture and store water and let it seep into the soil before overflowing into the sewer.
Not only does it make a better place to live as you generally need plants to use that water, but its the only way to capture it at scale. I live in a swamp, and right now is the time of what I call "the big slurp" where all the plants turn green, and the high water from winter that has the water table at ground level will drop 6 inches as every plant turns into a straw. It happens over 3-4 days and its wild to see.
A bigger and bigger sewer is the "just one more lane" to fix traffic congestion. It doesn't work, definitely not as a singular solution. https://www.theguardian.com/world/2017/dec/28/chinas-sponge-...
The area around London is fairly water stressed, indeed is in some ways a desert, amazingly AFAIK.
Maybe part of the solution is to reduce rain/stop runoff that then overwhelms the sewage system.
I understand that Thames Water may get powers to charge people (eg homeowners) a fee who have flouted regulations such as SuDS by making their surfaces impermeable and thus added to the problem, eg concreted over their front garden.
I understand that Thames Water may get powers to charge people (eg homeowners) a fee who have flouted regulations such as SuDS by making their surfaces impermeable and thus added to the problem, eg concreted over their front garden.
Allowing rainwater to seep into the ground instead of redirecting it into the nearest river to flow out into the sea is definitely important, and something previous (and current) generations have put too little effort into.
At the same time this can be very hard to retrofit. Having a lawn instead of a concrete pad is only a small part, you need areas that you are willing to allow to flood in a rain event. London wasn't built with this in mind, so any significant improvement that would make improvements to the sewer system unnecessary take way too long.
At the same time this can be very hard to retrofit. Having a lawn instead of a concrete pad is only a small part, you need areas that you are willing to allow to flood in a rain event. London wasn't built with this in mind, so any significant improvement that would make improvements to the sewer system unnecessary take way too long.
That's what two people in the article who were quoted in opposition to each other were both saying. The difference is the London Waterkeeper guy was saying it needed to be done immediately and the Thames Tideway guy was saying that they built the tunnel to buy 60 years to do it. But they were in agreement that keeping water out of the sewer was the best way to handle it. It sounds like they just didn't know they agreed with each other.
>"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.