The slag heap of Hénâ - A second life for an industrial site

The slag heap of Hénâ is located in the municipality of Flémalle. The site was originally comprised of two large valleys, which were home to the Hénâ Creek and the Fagnes Creek. The slag heap at Hénâ is composed of coal combustion residuals of the former coal-fired power plant at Les Awirs.

Revitalisation of an industrial site into a new biodiverse zone: a unique site in Europe!

With this ambitious project, ENGIE Electrabel reinforces its role as a responsible industrial company. From 1952 to the end of 2016, more than 2.33 million tonnes of coal ash were buried in two valleys in the Flémalle region. Today, ENGIE Electrabel is restoring the site. 

This site is unique for several reasons:
•    It will be restored to its original state and will once again become a biodiverse green zone for local residents;
•    Thanks to an agreement with the cement factory, the coal ash from the slag heap will be given a second life. After transport by ship, a highly sustainable form of transport, it will be recycled;
•    Finally, ENGIE Electrabel places great importance on the well-being and support of local residents. The ash will be transported via a closed conveyor belt, which reduces noise pollution and the accumulation of residues to an absolute minimum. Local residents, authorities and academic experts have been, are and will continue to be involved from start to finish.

With this project, ENGIE Electrabel shows that it is meeting its long-term commitments across the cycle, from development, building and operation to dismantling and redevelopment.

If you have any questions, you can reach ENGIE Electrabel on 0800 20 210 or via It goes without saying that a project of this size is set up in close collaboration with the authorities. The municipality of Flémalle acts for your safety.


The latest update on the slag heap


We regularly distribute brochures to local residents to inform them about the progress of the works.

In the issue of March 2021 we highlighted:
•    the milestone of 770,000 tonnes of ash evacuated since 2016 
•    the results of 4 years of work on the slag heap of Hénâ.


The site before the removal of ash


The removal of the ash is still in progress. To date, more than 770 000 tonnes or 30% of ashes (March 2021) out of a total of 2.33 million have been removed from the site. The removal work started in 2016 and will take 15 years. ENGIE Electrabel has invested a total of more than 50 million euros in the redevelopment of this former industrial zone.

The safety and well-being of the local residents is a top priority. That is why ENGIE Electrabel has implemented more than 60 recommendations from the Environmental Impact Study conducted by the authorities.

More information about the site

Reassuring results


Asbestos was found in the slag heap area. ENGIE Electrabel did everything possible to ensure that the asbestos removal work was carried out safely, efficiently and in the strictest respect for safety standards. That is why air quality measurement campaigns were conducted monthly by an independent company. 


Want to find out more?

Read our newsletters and publications about the slag heap at Hénâ. (FR)