- The producers of the Arcachon basin can continue to serve their oysters on the markets, in shops or at the hut, insists the regional shellfish committee.
- The basin has been spared thanks to a very efficient sanitation network system.
- Set up fifty years ago, this network bypasses the entire basin to discharge used and treated water into the ocean at the La Salie wharf.
Due to the detection of "norovirus", the most common cause of gastroenteritis, 23 shellfish growing areas - mainly on the English Channel and the Atlantic coast, as in Charente-Maritime - have been closed since the beginning of December, and "more than 400 companies are affected by these restrictions. Fishing, collection and marketing bans have been issued in the production areas concerned.
What about the Arcachon basin? "No contamination is to be deplored in our production area" insists the regional shellfish farming committee Arcachon-Aquitaine. “Our producers can therefore continue to serve their oysters on the markets, in shops or at the hut. This also concerns the oysters from the Médoc and Hossegor. 20Minutes explains why the pelvis was spared.
What explains that the oysters in the Arcachon basin are not affected by the gastro virus?
"All territories are not equal in the management of their waters," says one side of the regional shellfish committee. Thus, the Arcachon basin “has a very efficient sanitation network, allowing the marine environment to be preserved. The gastro virus can indeed survive in wastewater collectors, and contaminate a production area if there is contact between the two.
What is special about this sewerage network?
Created fifty years ago, the Arcachon basin sanitation network completely surrounds the basin, and there is therefore no direct discharge into the basin. "The discharge, after treatment, takes place in the ocean outside the basin, in a highly stirred place where the rate of dilution and diffusion is extremely high, without any return to the basin", insists Sabine Jeandenand, Director General of Services of Siba, the Intercommunal Syndicate of the Arcachon Basin. “In addition, our network does not include any storm overflow, which means that the basin is protected. "This system is" completely atypical, since it is found only around Lake Annecy, "adds the director.
What equipment is it made of?
Managed on the scale of the 12 municipalities bordering the Arcachon basin, this network is made up of a pipeline [a collector] which leaves from the tip of Cap-Ferret and which crosses all the municipalities up to Biganos, place where finds the first treatment plant. "A network of 420 pumping stations brings the wastewater back to this collector," explains Sabine Jeandenand. We are thus equipped with 1,200 km of network for the territory, which is very substantial in terms of our surface area. "
Where is the wastewater discharged?
From Biganos, a large pipeline takes the water treated by the station, 15 km further, to the wharf of La Salie. "The papermaker Smurfit Kappa, in Biganos, has its own treatment plant, and its water also joins the same collector," adds Sabine Jeandenand. Likewise, it collects the wastewater from the La Teste treatment plant, which treats the municipalities of the south Basin, as well as the treated water from the small station at Cazaux. "
The discharge of treated water into the ocean is a common practice, all along the coast. But the peculiarity of the La Salie wharf, “is that it is an overhead pipeline, therefore visible, while the other discharge points from the coast are buried and cannot be seen. "
This collector treats 30,000 m3 of urban water (for 120,000 inhabitants) and 30,000 m3 of industrial water every day.
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- Aquitaine
- Arcachon
- Virus
- Bordeaux
- Gastroenteritis
- Oysters
- Planet
- Consumption