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Comment by Mistletoe | Hacker News Reader

>For the 2024 Summer Olympics, swimming events will take place in that river, so authorities have spent $1.6 billion on a solution. They dug a giant reservoir to capture untreated sewage before it flows into the channel.

https://www.npr.org/2023/07/26/1190123421/after-100-years-pa...

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What I distilled.

Paris like most older cities has a combined storm and sewage system. The problem always is when there is too much rain the treatment plant can't handle the volume so it get dumped into the river untreated. To fix that they're building a huge holding reservoir so they can capture sewage + storm water and feed it slowly into the waste treatment plant instead of dumping it into the Seine.

Added. I've read elsewhere that the Seine is often safe to swim in already. Hope is this will turn often safe to to always or usually safe.

There have been quite a few improvements since I've lived in Paris (early 2000s). I've never really tried the Seine itself, but did quite a few swims in Marne (its tributary that flows in just outside the inner city limits) and the canals.

So before the worlds elite athletes were coming to town, a clean river wasn’t worth it?

They have been cleaning it for decades now, they did not start just now. It’s more of an impetus to go all the way to make it swimmable. In the end, who cares as long as the result is there?

It matters because (imo) society’s priorities are wrong here and if we identify that maybe we can discuss it and persuade people.

Agree that it’s a great result overall!

In this case, you can rest assured that they’ve been doing a huge amount of work (both politicians enacting regulations, although funding could always have been better, local councils who worked on policies and outreach, scientists, and engineers) for the sake of having a clean river and more biodiversity. This effort more or less started in the 1990s. Chirac, who used to be Mayor of Paris, promised to swim in the Seine within 3 years when he unveiled a cleaning up effort in 1988. Which was obviously propaganda, but still the will was there.

Yes. Entertainment brings in money which can be used to pay for things with positive externalities.

> “I bid for the Olympics because it’s the only way to get the billions of pounds out of the government to develop the East End,” he said in 2008.

Ken Livingstone, former mayor of London. It's not for the athletes, but it's because of them.

It didn’t pan out as great value for the tax payer though.

Out of curiosity, does this imply there is some permanent solution implemented here that will benefit the river after the Olympics as well?

I can imagine that having a clean river is good for many things, and they will keep using this facility?

I don’t know what paris is doing here, but I doubt it.

It’s fairly standard practice for triathlons to dump a whole bunch of bleach into a lake or river to make it safe to swim in for a couple of days, but without continual treatment it quickly goes back to normal.

> It’s fairly standard practice for triathlons to dump a whole bunch of bleach into a lake or river to make it safe to swim

I'm not sure where this might be standard practice, but this would be very illegal in most of Europe. So that's not what is going to be done (as explained in the article).

definitely illegal in Europe, never heard of it. Wouldn't that massively hurt the environment???

Yes the goal is that three spots will become permanent in 2025.

Yes, they built some major infrastructure to deal with the run-off problem.

Here's an article with more details: https://www.bbc.com/news/world-europe-66238618

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