00:00 Swimming in the Seine has long been forbidden, but taking a dip in the iconic river could
00:16 soon become a reality.
00:19 Just in time for the 2024 Summer Olympics, Paris has embarked on its most ambitious bid
00:25 yet to clean up one of the world's busiest waterways.
00:30 We have not been able to swim in the Seine since 1923.
00:38 We have been working for several years to improve the quality of the water to allow
00:46 us to swim again.
00:47 As part of the 2024 Paris Olympic and Paralympic Games, there will be several events in the
00:56 Seine.
00:57 The first will be at the foot of the Alexandre III bridge, the triathlon men, women and mixed
01:02 relay.
01:03 The paratriathlon will also be held during the Olympic Games and free-swimming.
01:08 It is a 10-kilometer event that will be in a loop.
01:10 It's not crazy, it's an ambition.
01:15 First, the Games have allowed us to accelerate a certain amount of investment that will
01:20 allow us to improve the quality of the Seine and to be able to swim again for the
01:25 next few years.
01:26 First, the Olympic and Paralympic Games, and then the Parisian swimming will start
01:30 in the summer of 2025, a year after the end of the Olympic and Paralympic Games.
01:35 The overall budget for the Seine's sanitation has been valued at about 1.4 billion euros
01:43 over 8 to 10 years and it focuses on a certain amount of investment necessary to improve
01:48 this quality of water.
01:49 All this is done in a very regulatory framework.
01:54 We must meet European water quality requirements.
01:58 The quality is improving.
02:02 Last summer, for example, on the site that will host the Olympic and Paralympic Games
02:08 events, on the period of the Olympic Games, so on the 15 days, 92% of those days, the
02:13 quality of the water was satisfactory or excellent, so it would have allowed the hosting of these
02:17 events.
02:18 The requirements of the International Federation will be met here in Paris, the quality of
02:24 the water will be good.
02:25 Without the Games, we would have probably arrived, but maybe in 30 or 40 years, which we would
02:30 have been able to do in 8 to 10 years.
02:33 We are now meeting in the summer of 2025, all in swimsuits, to enjoy and discover the
02:38 Seine from a different perspective than the one we have today.
02:47 Paris has made the Seine its leading star in the upcoming Olympics, but not many people
02:52 would brave its murky waters just yet.
02:56 The iconic river has built a filthy reputation as a dump yard for all sorts of trash, plastic,
03:03 cigarette butts and even electric scooters.
03:06 More than 350 tons of waste are hauled out of the Seine every single year.
03:13 But the biggest hurdle to making the Seine swimmable could be the seedy sewer system.
03:19 It combines stormwater and sewage water before they reach treatment centers.
03:24 When heavy rain hits, the system can easily be overwhelmed, discharging contaminated water
03:31 back into the river.
03:33 Nearly 2 million cubic meters in 2022.
03:37 The French capital now plans to curb water pollution for good.
03:42 Flooded boats and thousands of homes along the river will need to be hooked up to the
03:46 seedy sewage system before 2024.
03:51 Cleaning up the Seine has been years in the making.
03:54 Officials say the amount of wastewater entering the river is now 90% lower than 20 years ago.
04:02 But how clean is clean enough?
04:04 And what will it take for Parisians to finally take the plunge?
04:11 "We are now on the edge of the Seine.
04:22 I was taken in by water to check the amount of fecal bacteria that was present in the water.
04:31 We have to measure the presence of two species of bacteria, Escherichia coli, and on the other
04:48 hand we have to measure the presence of enterococcus intestinalis.
04:51 These are fecal bacteria of human origin.
04:56 They come from the main waste water networks.
05:03 The second potentially important source is other warm-blooded animals that we would have
05:09 in the city.
05:11 These fecal-indicating bacteria are not dangerous in themselves.
05:15 Their interest is to be indicators of the presence of fecal pollution.
05:22 And if there is fecal pollution, there is a risk that viruses, for example transmitted
05:28 by the feces of men, are also present.
05:31 And these viruses could be dangerous viruses.
05:35 Back at the lab, we're going to put the water in small bottles with products that will
05:44 allow these bacteria to grow.
05:46 We're going to place them in a 37-degree storage for 18 to 24 hours.
05:53 When bacteria are present in the water, the manipulation we do will make a blue or yellow
06:00 color appear depending on the types of bacteria that are present.
06:05 Currently, we are in a range between 100 Escherichia coli per 100 milliliters to about 1,000, 5,000.
06:17 For the water in the Seine to be declared bathable, it must be below 900 Escherichia coli
06:24 per 100 milliliters for 90% of the time.
06:29 Fecal bacteria are always present in the Seine.
06:33 Always.
06:34 It's not because we have a few fecal bacteria in the Seine that we can't bathe.
06:40 It's all a matter of standards, of levels.
06:43 The level must be low enough for the risk of catching a disease in the Seine to be extremely low.
07:02 Here we are on the site of the Stairlitz basin, the largest operation of the Parisian sanitation network.
07:08 This project costs 90 million euros.
07:15 It's like a big underground pool.
07:17 The purpose of this basin is to give the sanitation network a storage capacity during rainy seasons.
07:31 To fill up, to let the storm pass and to avoid these spills in the Seine.
07:36 When it rains, the volume of water in the sewage network suddenly increases very significantly.
07:44 To avoid overflows in the streets, we use water and we use the Seine as a safety valve.
07:53 The Seine is used as a "sewer" to "empty" the sewage in a way that is too regular by overflows.
08:01 Tomorrow, thanks to this project, it will be intercepted via a pipe of 2.5 metres in diameter and 600 metres long between where we are and the Stairlitz bridge.
08:13 The water flows gravitally into this interceptor, reaches the basin, which is 50 metres in diameter and 30 metres deep.
08:20 The volume is equivalent to 20 underground Olympic swimming pools.
08:24 The next day, after the rain, in less than 24 hours, we pump this water from the basin, we put it back in the sewers of the hospital boulevard.
08:33 It will flow to the sewage station to be treated before being sent to the natural environment.
08:38 This type of project will reduce the spills in the Seine and therefore simply improve the ecological state of its ecosystem.
08:48 The state of the water and therefore the quality of the water also in a sanitary sense.
08:52 The Olympic Games, with the effect of swimming for the athletes and then for the general public afterwards,
09:01 allowed us to give a boost, an acceleration, for the improvement of the ecological state of the Seine.
09:08 There's one thing, however, that these massive works cannot fix.
09:14 The unpredictability of the weather. Sudden storms could still put pressure on a fragile system.
09:21 Modernizing wastewater treatment plants remains a key pillar of the French capital's strategy.
09:28 Today, the treatment plants are already effective.
09:40 It is about being even better, adding additional treatment stages to contribute to the achievement of the Béniade objective.
09:47 Among the actions undertaken within the framework of the Béniade plan, there is the modernization of the Marnaval factories and the Seine-Valentin factory.
09:59 It is about integrating dedicated treatments into the treatment lines to eliminate fecal bacteria.
10:08 The Marnaval factory will be equipped with ultraviolet lamps.
10:11 The wastewater that has been treated, that is, the organic matter, nitrogen, phosphorus, will be removed,
10:18 and the wastewater will be passed through the ramps of ultraviolet lamps.
10:23 The light will irradiate the water and, as a result, the bacteria still present will be killed, deactivated.
10:33 It must be kept in mind that very low volumes of wastewater introduced into the river bring large quantities of germs.
10:40 100 milliliters of wastewater contain several million germs.
10:44 When this wastewater passes through our treatment lines, it emits a large part of it.
10:49 This is good, but it is not enough to achieve the Béniade objective.
10:54 The fact is that by using or adding these treatment stages, we will still divide the concentrations in the water that we will return to the river by a thousand.
11:04 The two wastewater plants have, of course, very strategic positions, since they are located at the entrance of Paris.
11:11 All the efforts that will be made on these plants to gain treatment performance,
11:15 we will see it on the quality of the river that will enter the city of Paris.
11:21 The collection basin of the Parisian agglomeration is exceptional.
11:24 I remind you that more than 9 million Franciliens are installed on a river with a low flow rate.
11:30 And every day, these 9 million Franciliens generate about 2 million cubic meters of water, 2 billion liters.
11:38 So we can see the very sensitive nature.
11:40 This allows us to appreciate the extent of the challenge.
11:43 And this challenge is possible because, for 50 years,
11:46 efforts have been made to improve the robustness and performance of these treatment plants.
11:51 We can be quite optimistic about our ability to achieve this goal.
11:56 [Music]
12:03 (upbeat music)
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