The rehabilitation of a former industrial site: an ecological challenge successfully met
The rehabilitation of former industrial wastelands has become a crucial issue both economically and environmentally. Faced with growing urban expansion and real estate pressure, these wastelands represent a challenge for the coming decades. In this context, the rehabilitation of the Rive de Gier site, with a strong emphasis on ecological issues, has emerged as a necessity to meet government objectives, in particular the ZAN challenge (Zero Net Artificialization of Soils) set for 2050. This major challenge aims to limit the increase in artificial surfaces by freeing up land.
An essential restoration to prevent the risk of flooding:
The Rive de Gier site presented an increased risk of flooding, as evidenced by the 2008 flood that affected the city center. To avoid the repetition of such events, public authorities have therefore taken measures. The main mission of this rehabilitation project led by Colas Environnement was therefore to prevent the risk of flooding by redeveloping and widening the banks of the Gier river bed.
A comprehensive strategy to restore the watercourse:
In order to achieve this objective, Colas Environnement has undertaken recalibration work on approximately 800 linear meters of the watercourse, while seeking to restore its ecological and morphological functionalities. In addition, fishing operations have been carried out, with more than 300 kg of fish released downstream. In total, nearly 90,000 m3 of material were then used, half of which was reused on site and some of which was screened for various treatments. The earthworks required the temporary diversion of the Gier into a lateral canal in order to carry out the remodeling of the bed.
Exemplary management of materials and the environment:
The management of materials impacted by organic pollution has obviously been carried out in such a way as to comply with the standards in force. Colas Environnement has followed an approach of approved supply chains for materials, with the management of 35,000 tonnes treated and more than 49,000 m3 reused on site. The company collaborated closely with Saint-Étienne Métropole, benefiting from the project management support of VDI and SOCOTEC Environnement for the pollution control part. Thus, the restoration of the site allowed the watercourse to extend over an area of 45,000 m2, three times more than before the work.
Conclusion:
The Rive de Gier site rehabilitation project represents a concrete example of the successful conversion of a former industrial site. By focusing on ecological issues, this restoration made it possible to prevent the risk of flooding while restoring the natural functionalities of the watercourse. With materials management, close collaboration with public authorities and pollution management, Colas Environnement has been able to breathe new life into this page of more than 200 years of industrial activity. This project is a real success for the environment, the region and the local community.