Our achievements

Discover examples of our construction projects and engineering projects.

Rehabilitation of an old refinery

The deconstruction/depollution site of a former refinery in Dunkerque, managed by Colas Environnement, is one of the largest deconstruction projects in France. Initiated in 2017, the work covers an area of 90 hectares and aims to dismantle existing infrastructures while treating soils contaminated by hydrocarbons and heavy metals. A major innovation of the project lies in the use of BIM (Building Information Modeling), a first for a deconstruction/depollution site, allowing precise modeling of the pollutant mass present and their spatial distribution. In addition, a vacuum extraction unit, designed specifically for this project, worked continuously to treat approximately 4 Ha over 3 to 4 m deep for 3 years. Finally, around 20,000 m3 of soil were excavated and treated on site via bioremediation. Materials from deconstruction are recovered, including the recovery of 45,000 tonnes of scrap metal and 300,000 tonnes of concrete reused on site. This project illustrates Colas Environnement's commitment to social responsibility and the sustainable rehabilitation of industrial sites.

Rehabilitation of an industrial site by thermal desorption (ERH)

Colas Environnement used Electrical Resistance Heating (ERH) to treat the soils of a former industrial site contaminated by chlorinated solvents, installing 91 heating electrodes as well as the structures necessary to extract the gases emitted. The aqueous and gaseous effluents were treated with 8 activated carbon filters.

Reconversion of an industrial wasteland into a business center

Long dedicated to industry, a former wasteland has been rehabilitated to become a modern leisure and commercial center. Colas Environnement has treated more than 33,000 tons of soil contaminated in particular by volatile organic compounds (COHV), PCBs and hydrocarbons. More than 1,000 trucks were mobilized for this operation. The latter, conducted in collaboration with other subsidiaries of the Colas group, illustrates our expertise in pollution control and contributes to the national objective of the ZAN “zero net artificialization”.

Treatment of PFAS impacted aquifers

Faced with the growing problem of PFAS, Colas Environnement carried out an intervention in Belgium to treat a water table impacted by these “eternal” substances. As part of road redevelopment work, a 15 m³/h treatment unit was first installed to validate the reduction in concentrations, followed by an installation capable of treating 50 m³/h with 18 tons of filtering media. A second unit has been set up to further improve the filtration process. The results showed a total reduction in pollutants, paving the way for the generalization of these treatments in Belgium and France.

Rehabilitation of a wasteland via mixed depollution (off-site and in situ)

A former industrial site has been depolluted in order to change its future use. This project aimed to eliminate contaminations inherited from decades of industrial activities. The depollution took place in two phases: the demolition of 18,000 m² of paving and the evacuation of 4,230 tons of polluted material into approved channels, followed by treatment by Sparging and Venting with 16 sparging wells at a depth of 17 meters and 61 venting wells at a depth of 6 meters.

Rehabilitation of a former industrial site

Colas Environnement, in partnership with PERRIER TP and TPCF, subsidiaries of the Colas group, has completed a project to redevelop the banks of the Gier, aimed at reviving a former industrial site. This project involved the recalibration of 800 meters of the watercourse, with the removal of 17,500 m² of slabs and the earthworks of more than 90,000 m³ of materials. This initiative serves as a model for other site rehabilitation combining expertise in large-scale earthworks, ecological engineering and soil remediation, contributing to local biodiversity while meeting the challenges of zero net artificialization (ZAN).

Sustainable rehabilitation in a tent in the heart of the city

In the heart of La Roche-sur-Yon, Colas Environnement participated in a rehabilitation project transforming the location of a former car garage into a living space compatible with health conditions. Our teams in collaboration with Premys, a Colas subsidiary specialized in deconstruction and asbestos removal, guaranteeing an integrated and effective approach. This project testifies to our expertise in the depollution and rehabilitation of contaminated sites. The work included the earthworks of 3,300 tons of materials impacted by BTEX hydrocarbons, as well as the installation of a 30 m by 25 m ventilated tent to control gaseous emissions during earthworks. Thanks to a ventilation unit filtering the air at a rate of 13,000 m³/h, the safety of local residents was ensured while maintaining the environment.

Air treatment specifically for odors related to bitumen smoke in Croatia

In a world that is increasingly concerned about air quality, Colas Environnement solved an odor problem on an asphalt manufacturing site in Croatia. Our teams quickly implemented a ventilation method to capture and treat the smoke, thus guaranteeing the continuity of operations. Based on our experience with nearly 30 similar installations, we have achieved more than 99% odor reduction thanks to the installation of tailor-made processes and remote performance monitoring.

Rehabilitation of a former gas factory: an ambitious project in Aurillac

To revitalize the urban environment, Colas Environnement and its partners have launched a project to revalorize a former gas factory. In collaboration with Colas and Perrier TP, our teams tackled the depollution of this historic site, which was active until 1950 and was contaminated by hydrocarbons, BTEX, PAHs and cyanides. The work included soil sampling, earthmoving with machines equipped with air filtration systems, the ventilated storage of materials awaiting evacuation, as well as the management of non-reusable waste via approved channels. With an objective of eliminating 90% of the pollutants identified and an estimate of 13,000 tons to manage, this project illustrates the commitment of our teams to carry out complex projects in a constrained urban environment.

LED pilot tests

Since 2006, an industrial site has been the subject of several studies, leading to a Management Plan drawn up by a specialized design office. The diagnoses highlighted the presence of hydrocarbon and chlorinated solvents impacts on sandy-gravelly embankments, threatening a nearby alluvial aquifer. Pilot tests, including biodegradation in the laboratory and pumping-skimming and sparging-venting systems, were implemented by our teams in order to test the effectiveness of depollution methods. These actions aim to effectively treat pollution sources and areas of concentrated pollution while ensuring the protection of the environment and compliance with current regulations.

Rehabilitation of service stations — Post-disaster emergency response

Our teams were engaged in depollution work at an active service station, aimed at eliminating the impacts of hydrocarbons in soils and groundwater. We thus created a draining trench to limit the migration of pollutants, excavated several hundred tons of impacted soil under sliding armour, evacuated the latter into approved off-site management systems, and set up a pump-skimming system to treat groundwater by phase separation. Thanks to effective cooperation, we were able to ensure the continuity of the activity while guaranteeing the rehabilitation of the site.