Securing slag deposits

The southern coastline of Marseille
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For over a century, historic deposits of industrial waste have been polluting the coastline of the Calanques of Marseille between Madrague de Montredon and Callelongue. Known as ‘slag’, these deposits are visible at the roadside, on beaches, in the countryside and sometimes even in the water. ADEME (the French Environment and Energy Management Agency) has been commissioned by the State to treat and secure the sites identified as being the most polluted. This historic decontamination project is being led by the State with financial support from the City of Marseille and other local authorities co-funding the project.

Updated on 21 July 2026

A major project

This safety-related project, entrusted to ADEME by the State, is a major public interest initiative that has been under discussion for many years and is finally coming to fruition. The project aims to reduce the environmental impacts of this pollution and the public’s exposure to it.

The following co-funders – the City of Marseille, the Department and the Metropolitan Authority – are involved in this project, which is led by ADEME. They also sit on a Monitoring Committee that has been meeting at the Prefecture for several years and which includes representatives of local residents, such as the local residents’ committees (CIQs) in the area, as well as organisations active in the fields of the environment and health.

Organisation of the construction site

The works programme is organised into two distinct phases. The first phase took place from September 2025 to May 2026. To date, all areas affected by the works have been reopened to the public.

However, certain works planned in the Saména calanque (DSa03), at the Port de l’Escalette (DEs01) and in the Trous calanque (DTr01) could not be completed during this first phase. Their completion has therefore been postponed to the second phase of works, scheduled for autumn 2026. In the meantime, temporary safety measures and information signs have been put in place to ensure the safety of visitors.​
At Samena, access to the beach remains open thanks to the new stone staircase built between the terraces. However, the terraces themselves remain closed to the public until the works are completed. Barriers have been installed on either side of the staircase and at its top end to mark off the areas still under construction.​
At L’Escalette, a temporary surface has been laid between the road and the containment structure that has been put in place. This solution allows access to the car park to be maintained whilst ensuring that the slag on the site is contained. In addition, concrete blocks have been placed to prevent this space from being used as an acceleration lane for vehicles.​

The second phase of works (September 2026 – March 2027):

  • will mainly concern the storage areas located between Les Goudes and Callelongue;
  • the location of the associated site facilities will be announced during the summer of 2026.

Photos of phase 1 of the works

Important

Please note that during the two periods of works, parking will be limited in this area and traffic conditions will be disrupted. Visitors are therefore advised to use public transport to reach the area:

  • Public transport (lines 19 and 20, LeVélo stations) has been enhanced, with services running until 11.00 pm and a frequency of every 20 minutes all year round (visitthe RTM website for more information).
  • Parking spaces have been made available to restaurant owners.
  • For motorists arriving in the area before midday, visitor car parks :
    – Calanque Blanche
    – Escalette
    – Car park adjacent to the Napoléon car park.
    Parking on the road is prohibited
  • A temporary parking zone reserved for local residents is currently being considered.
  • Self-service electric bike stations:
    – LeVélo available at La Madrague, Saména, L’Escalette, Les Goudes and Callelongue.
    – The Lime and Voi services cover the entire southern coastline as far as Callelongue