Polluted sites and soils: huge health, environmental, technical and financial challenges

Hello Nicolas. According to a simple definition, a site is polluted when a substance not present in its natural state is detected in its soil, resulting in an unacceptable risk for the targets to be protected and for a given use of the site. Where are we in France on this subject? Which pollutants are most present in our soils? What are the regulations and what are the issues?

In metropolitan France, the situation is heterogeneous and mainly the result of the country's industrial history. In this respect, some regions are historically more impacted than others, notably the north of France, the Rhône-Alpes region and the Ile-de-France. Under the aegis of the Ministry of Ecological Transition, an official database, Basol, collects and stores several thousand polluted or potentially polluted sites and soils requiring preventive or remedial action. This database currently lists 6,838 sites with proven pollution. Another database, Basias, lists 340,000 industrial sites, without prejudging whether each site is polluted. Inventories are not carried out everywhere in Europe, nor are they necessarily based on the same criteria. It is therefore difficult today to place France in the European context. In any case, we have the merit of having carried out these studies and we are observing regulations that are becoming stricter with time. As regards pollutants, we mainly find the families of hydrocarbons, chlorinated solvents, various mineral pollutants (metals), and more and more 'emerging' pollutants of the PFAS type.

Each study area is unique. Many questions must be answered: What industrial activities are listed? How were the sites exploited? For how long? In what geological context? Has the pollution impacted water resources (underground or in rivers) or sensitive natural sites?

An approach is made on a case-by-case basis, depending on the history of each site. We obviously rely on the national methodology for characterisation, and develop specific management solutions accordingly. In this area, we carry out research and development activities, integrated into the feasibility studies. The multiplicity of operations carried out and the solutions brought to bear enable us to have significant know-how from which we benefit on new projects. In addition to health, environmental and technical issues, there are also financial issues and cost optimisation issues which can sometimes represent hundreds or millions of euros, and on which the realisation of the project often depends.

Generally speaking, it is the future project on a site to be developed, typically a former industrial wasteland, that will guide the means and condition the nature of the actions to be carried out to rehabilitate a site, whether it is an industrial or residential project or a natural area. Our market should experience sustained growth in the future with the desire to stop the artificialisation of land in development projects (20,000 hectares of natural areas were artificialised each year between 2006 and 2016). The legislator and local authorities will henceforth favour the rehabilitation of former industrial wastelands. Among the most recent signals, logistics warehouse companies have committed to limiting the artificialisation of land as part of the signing of a charter between the government and e-commerce players last July.

To conclude this overview, I would add that there are many regulations to be complied with, such as the Environmental Code, the Civil Code (hidden defects), and the Labour Code with the obligation for company directors to protect their employees. It is precisely the complexity of the rules that makes the support of a third-party expert so valuable. The latter will have a global vision of the project in order to anticipate the risks as well as possible and imagine the right solutions. On this point, and for our clients, as is often the case, it is the anticipation and consideration of all the dimensions of a project that will make it successful. 

There is a lot of talk about data management to imagine solutions, can you tell us more?

It is undeniable that we are dealing with a subject that encourages innovation and R&D. The first project is ultimately that of knowledge. To carry it out successfully, all our employees in the field need to be efficiently equipped to collect information. This is why we are in the process of deploying tablets to our employees in order to industrialise data entry and collect all the data that enriches the databases. Today we collect billions of data. As the data is geolocalised, we can map projects, offer geostatistical analyses, compare projects and management solutions and capitalise on new projects. Today, data processing is essential on the scale of a territory, of a community, and we can assist them in these matters to map, parcel by parcel, the environmental state of a given territory. This is an additional layer that can be integrated into the Geographic Information Systems (GIS) that local authorities will use. All this knowledge makes us more 'intelligent' today in finding the best solutions both for the environment and for optimising the costs of a project or rehabilitation. For example, as part of an assignment for the Saint-Etienne urban area for the construction of the tram, we worked on the screening of polluted soil, for recomposition and reuse of unpolluted soil. The result is an environmental success and very significant savings for the community. The treatment of polluted soil represents a significant cost. On the solution side, Apave is the project manager and can coordinate various partners, in particular local companies that know the terrain particularly well. This ability to work with other players and to coordinate a project is only possible because we have the global approach I mentioned earlier.