Dammarie-lès-Lys industrial site

Seine‑et‑Marne, Île‑de‑France, France

Dammarie-lès-Lys is an industrial site in the Clos Saint-Louis neighbourhood in Seine-et-Marne, on the outskirts of Paris, France.

Dammarie-lès-Lys has a long industrial history, hosting an aluminium foundry from 1917 to 1984. Following the foundry’s closure, the site was used for a range of industrial activities including ferrous metal processing, steel cable coating, and recycling until 2006.

The site comprises 2 areas: a 43,256m² rehabilitated industrial zone located at the southern end of the site, and a 10,000m² landfill site at the northern end that stored foundry slag.

Rio Tinto did not operate the site, but we are responsible for its remediation through our acquisition of Alcan in 2007.

We finished rehabilitating the main operational part of the site in 2018, and in December 2024 we began remediating the landfill site for future industrial use. We expect to complete the rehabilitation project in early 2027.

Dammarie-lès-Lys rehabilitation overview

At Dammarie-lès-Lys, outside of Paris, we are rehabilitating a former industrial site that was once the home of an aluminium smelter and recycling facility. We did not operate the site but assumed responsibility for its remediation following the acquisition of Alcan in 2007. The project is safely removing and treating legacy waste inside a purpose-built containment tent, designed to minimise dust, odour and other potential impacts on the surrounding environment.

Once remediation is complete, the area will be backfilled with clean material and prepared for future industrial use.

Remediation needs

Dammarie-lès-Lys is part of a broader brownfield regeneration area with a long industrial history.

The site stores smelting residue (slag) which consists of dark-coloured, sandy materials with a high ammonia content. When disturbed by machinery or exposed to rainwater, the slag can release ammonia and emit unpleasant odors. We’re managing these risks carefully as part of the remediation project.

Prior to 1986, the slag was stored directly on the surface of ground. In the early 1990s, approximately 48,000m³ of slag waste was moved from the site and in 1991 a landfill cell was built to hold the remaining 38,000m³ of waste.

In 2013, we identified that the landfill cell was no longer fully sealed. Our environmental monitoring data showed that rainwater was infiltrating the cell, mixing with chlorides, and eventually leaking into the groundwater table.
The remediation work will help prevent future groundwater pollution and prepare the land for future industrial use.

Remediation progress

To help minimise leaks from the cell, in 2020 we pumped leachate from the landfill cell and treated the brine material.

In 2025, we began the next stage of the rehabilitation project, which involves excavating, sorting and disposing of the 38 000m3 landfill material at licenced facilities off-site and conducting earthworks to prepare the site for a future industrial use. We completed removal of the impacted materials in August 2026. We are now moving in the final phase of project, which includes backfilling the area, and removal of the tent expect this will be completed in Q1 2027.

To manage risks associated with the ammonia content of the slag, we installed a 150m × 50m containment tent, as well as gas extraction systems and 24/7 air quality monitoring both on-site and in the surrounding areas.

We regularly carry out environmental monitoring activities on-site and in the surrounding area, including:

odour and air quality monitoring
noise and vibration monitoring
dust emission monitoring, and
slope stability monitoring

To ensure the protection of workers on site, we implemented a monthly biological monitoring program to monitor potential exposure and safeguard the health of our personnel.

Due to the site’s proximity to the Seine River and nearby spawning grounds for some fish species, we’re carefully monitoring any impacts on water quality and the local fish species, including heritage or protected fish species such as the European eel, bitterling, pike, bullhead, allis shad, spiny loach, dace, and possibly brook lamprey.

Nuisance prevention has been a key priority since the very beginning of the project. This included the use of noise barriers during piling works and traffic management measures.

Working with partners and regulators

We’re completing the remediation work in full compliance with all applicable legal and regulatory requirements, under the oversight of DREAL, the French State's regional environmental authority, and the Municipality of Dammarie-lès-Lys.

We continue to hold regular meetings with the Municipality’s technical services, providing opportunities to share updates on progress, discuss upcoming activities and address any questions or concerns.

The project team works closely with local stakeholders and community organisations to monitor site access and occupancy, helping to ensure the safety and security of the site and surrounding areas.

Next steps

We expect to complete the rehabilitation project in Q1 2027. Once remediation is completed, the land will be suitable for future industrial use and available for redevelopment in line with local planning regulations.

Dammarie-lès-Lys history

Dammarie-lès-Lys has a long industrial history.

Opened in 1917, the Dammarie-lés-Lys plant was initially established to meet the needs of sugar refineries damaged during the First World War.

Located between the Melun–Corbeil railway line and the Seine, by 1950 the site comprised nearly 17 hectares and around 40,000m² of covered space, including 3 130m x 60m halls, a river wharf, and its own dedicated railway siding. It employed more than 700 employees at the peak of its activities.

Following the foundry’s closure, the site was used for a range of industrial activities including ferrous metal processing, steel cable coating, and recycling until 2006.

In July 1984, Pechiney took over the site. In 2003, Alcan acquired Pechiney and then Alcan was acquired by Rio Tinto in 2007.