Tokyo's Underground Discharge Channel | Hacker News Reader

Tokyo's Underground Discharge Channel

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96 pointsaashaykumar9240 comments

These enormous underground projects are so interesting.

I've been following the Chicago Deep Tunnel project, which is nearing completion after half a century of work.[1] Because Chicago was built on swampland and next to the lake, rainwater used to be a huge problem because it didn't have anywhere to go when it rains, except into sewers - which used to be well under capacity for burst rainfall, which led to basement flooding etc.

So the city is building (and almost finished with) a set of huge tunnels across the entire city that regular sewers will drain into during flash floods, and then pump the water out to reservoirs repurposed from abandoned quarries on the edge of town. The target capacity is 17 billion gallons, which is apparently the volume of twelve football stadiums stacked together? [2]

I'd love to tour that construction. Not sure they offer public tours though. :)

[1] https://interestingengineering.com/chicagos-deep-tunnel-proj... [2] https://www.mwrd.org/irj/portal/anonymous?NavigationTarget=n...

Milwaukee, WI is building a Deep Tunnel project as well. It's certainly not as large as Chicago's, but the need is similar (city built on swampland). They are, after all, neighboring cities on Lake Michigan.

https://www.mmsd.com/what-we-do/wastewater-treatment/deep-tu...

https://www.scientificamerican.com/article/sewer-diving-milw...

Massive side not - I have no idea why you guys insist on using football stadiums and football fields as a unit of measurement, what gives?

Just a handy visualization - easier to conceptualize than "12.9 billion gallons."

> 12.9 billion gallons.

You mean 39600 acre-feet? :)

Just yesterday, a street downtown buckled from the pressure of stormwater running underneath it.

1. https://wgntv.com/2019/05/01/video-captures-street-buckle-in...

>twelve football stadiums stacked together

I understand that football stadium play area is standard, but how do you measure height? Is it a foul to kick the ball too high in the air? The play area, I assume isn't limited vertically.

It says "volume of twelve stadiums" so maybe by treating an entire stadium as a giant bowl up to the top of the seating? But who knows what stadium is the reference stadium - that's not a consistent thing like the size of a football field.

Excellent point. I just wish they'd use the correct SI unit for this kind of thing - "libraries of congress".

Interestingly the recent late season rain has the Deep Tunnel almost full. [1] Two of the three main reservoirs are already at capacity, and the the last one is getting there.

BTW they do offer tours of the pumping stations, but not the tunnels [2]

[1] https://chicago.cbslocal.com/2019/05/01/heavy-rain-flooding-... [2] https://www.mwrd.org/irj/portal/anonymous/tourinf

DC’s Clean Rivers Project is building 4 long tunnels to act as a buffer for the old combined sewer system. Some of the tunnels are complete and already functioning. Previously large storms would cause the sewers to overflow into the Potomac and Anacostia rivers. The EPA wound up suing DC and the Clean Rivers Project is the result. The new tunnels have already had a huge effect.

https://www.dcwater.com/cleanrivers

Probably wouldn't want to be there today. ;) (Lots of rain, I think the tunnels are full.)

A couple years ago we stopped by the Lincoln Oasis (rest stop consisting of a bridge over the interstate that carried restaurants and similar instead of traffic.) As I was heading back to my car, I heard a loud whooshing noise and saw what looked like a geyser next to the ramp to get back on to the highway. I walked over to inspect and found a large grate fenced off and signed Chicago Water Reclamation (or something similar.) We had had a lot of rain the night before and apparently this was a vent to release air as the tunnel filled. The location is very near one of the quarries that is used to hold excess runoff.

Fun fact:

There is a software for modelling drainage systems called SWMM (Stormwater Management Model) that has been around since 1970s (!) and is programmed in C and released as free software. Still most modern drainage and sewer research is modelled via this software and there are several companies that built a GUI for simpler usage. However the core is often still based on this nearly 50 year old software which I find amazing [edit: it has been updated since then and originally it was written in Fortran].

The model has hydraulics and hydrology capabilities [0], i.e. it can model stuff like pipe pressure but also takes infiltration of stormwater (aka "rain") into the surface into account. When using it you have to define your sewer (which is mostly a directed graph) and so called catchments where you define which areas drain into which nodes (inlets) by defining parameters like impervious area, slope, etc. You can then let it rain on your area of interest (e.g. a city) and find out which nodes get flooded at specific points in time (or hopefully not).

[0] https://en.wikipedia.org/wiki/Storm_Water_Management_Model#H...

As of last year, they now offer hourly guided tours 7 days a week for about USD$10. (In fact, I was just there earlier today!)

Note: it's about 1.5 hrs (each way) from Tokyo, and you need someone in your group who can speak Japanese.

Reservations here: https://reserva.be/guidetour

Here are some pics from when I took this tour last year:

https://memorymulch.net/journal/2018/11/18/maoudc

It's amazing just how much stuff there is under Tokyo - not just infrastructure like this and the usual transport links but entire multi-storey shopping malls. There's almost a whole city beneath the city. It's possible to travel for miles without ever seeing daylight!

My favorite part is the JSDF underground bunkers where they store the giant robots used for disaster relief.

Where is this and how do I see it ?

It’s a joke, a mecha robot reference.

Osaka has also massive undergrounds. Not as large as Tokyo's of course, but massive nonetheless.

Even just the transportation infrastructure is incredible to me. I was just there and it was honestly amazing to me how deep the metro stations can be. Multiple long escalators/stairways from surface to platform.

Saw this BBC story on it last year:

http://www.bbc.com/future/story/20181129-the-underground-cat...

> 78 10 MW (13,000 hp) pumps that can pump up to 200 tons of water into the Edo River per second.[4]

Wow, I hope the grid can handle the relatively sudden appearance of 780 MW of load. I assume they have some protocol in which why turn on one pump at a time and coordinate with the grid operators.

I'm a bit worried that systems like this make the continued existence of large cities dependent on the availability of power and the resilience of power grids. It all works well enough usually, but when things go wrong, systems like that can make a bad situation a lot worse.

I've been there. The containment tank is positively MASSIVE, way more huge than what can be conveyed from those pictures. It took a good 3-5 minutes of walking down stairs just to reach the bottom of the tank floor, and once you're down there it takes some more to appreciate the expansiveness of it all. Definitely recommended if you're in the area.

Looks similar to the old Houston cistern - https://www.houstonpublicmedia.org/articles/news/2016/05/13/...

Is intake into that discharge channel controlled?

Flash flooding is a thing. In Hong Kong, the Drainage Services Department puts up warnings and runs TV ads to tell people to stay clear of discharge channels, lest they get swept away by flash flooding during heavy rains.

So if intake into the discharge channel is not controlled, isn't it kinda dangerous to film there?

The "temple" where filming is done is a secondary reservoir, it only receives water after the primary detention silos are full. So there is plenty of warning.

The picture "Metropolitan Area Outer Underground Discharge Channel" is startlingly similar to one of the scenes in the Mines of Moria (Lord of the Rings - Peter Jackson's movie.)

Tokyo was a city of canals before the Allies firebombed the city. Apparently the canals boiled due to the incendiaries used, so there was no escape from the fire during that tragic phase of life in the city. 100,000 deaths in one night is a statistic that few people think about, the Nazi death camps worked at a glacial pace in comparison, the craziness of WW1 campaigns gains a new perspective too, the bombing of Tokyo, with the loss of those canals, was something else. Hard to imagine. So we don't talk about it.

Tokyo was built on an estuary so the canals came from the management of the water that was already there. The final evolution being the water being pushed completely underground is pretty predictable. Other cities have dealt a similar fate to their rivers, London being a prime example where only the Thames is really 'welcomed' as a river, everything else is kind of banished underground.

Dresden was also completely destroyed by Allies (for no good reason) and its firebombing caused between 200 000 and 300 000 victims (largely women, children and elderly). We don't talk about it much even though it was a crime against humanity as well.

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

From the Wikipedia article supplied:

“Large variations in the claimed death toll have fuelled the controversy. In March 1945, the German government ordered its press to publish a falsified casualty figure of 200,000 for the Dresden raids, and death toll estimates as high as 500,000 have been given.[15][16][17] The city authorities at the time estimated up to 25,000 victims, a figure that subsequent investigations supported, including a 2010 study commissioned by the city council.[18]”

It’s a tragedy none the less but that figure doesn’t seem actuate ?

A single death is a tragedy, a million deaths is a statistic. - Stalin

Regardless of the deaths, I understand the cultural tragedy of the destruction of Dresden is significant as it was an important intellectual center.

I had a friend who passed away recently who was a boy in the bombings and recounted with tears on multiple occasions, as a lifelong opiate addict, how he felt he had personally died at that time. I visited the city a few years ago and found the largely depressing husk of a city still under wishful reconstruction. The nominal activity of its touristic center was at direct odds to the clearly economically depressed suburbs mere moments away.

Thanks for citing the statistics.

Just to be clear and provide context, the numbers the original poster linked were overbloated and inaccurate because it's a fictionalized neonazi talking point, like holocaust denial and white genocide in south africa. Some people get drawn into the, uh, wrong sources and start parroting the talking points without really knowing what they are helping to propagate, so the poster here might not be a racial supremacist or whatever, but it's something to keep an eye out for.

Nobody actually knows the real number of victims since it was not just the population of Dresden but also refugees from all over the place who had taken to live in Dresden. These are not accounted for by the city statistics, so 25 000 people killed is probably on the low end of actual numbers.

You want a different source? https://www.britannica.com/event/bombing-of-Dresden

> The U.S. Eighth Air Force followed the next day with another 400 tons of bombs and carried out yet another raid by 210 bombers on February 15. It is thought that some 25,000–35,000 civilians died in Dresden in the air attacks, though some estimates are as high as 250,000, given the influx of undocumented refugees that had fled to Dresden from the Eastern Front. Most of the victims were women, children, and the elderly.

I am not a historian, but there had to be a reason. Just from the popular accounts of WW II, given the conviction of Germans to continue fighting, their ideology, self-esteem and the danger of war dragging on, obliterating a major cultural centre instead of focused strikes to military targets makes a lot of sense, both emotionally and strategically. As I see it, this was by intent not a tactical response, this was meant to be a major death blow to hit the German resolve, so they see what response will come if they continue. And to make it a lasting impact. At that point of time, the Allies knew they will win, and they felt justified bombing vulnerable non-soldiers as a means to accelerate the coming of the end of the war. Similar logic applies to destroying the towns Hiroshima and Nagasaki with nuclear bombs.

Related previous discussion https://news.ycombinator.com/item?id=15436943

looks like a mirror's edge scene.. :)

Well yeah, the article says the location is used in mirror's edge.

Keep going, don't think those blues won't come down here.

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