1. When EEE becomes a major operational risk

The Seine-Bassée project mobilizes 120 hectares of restored wetlands for flood protection of the Seine. From the first phases, 19 invasive exotic species were identified, including three key species: Japanese knotweed, black locust and Spanish sainfoin.

This early identification is not a minor detail:

• a lot dedicated to the management of WEEE was launched a year before the other works;
• The technical specifications incorporate precise requirements for company competence and environmental awareness;
• Contractual penalties are provided for in the event of dissemination or lack of control;
• A monthly report is sent to the administration, along with a post-construction early detection plan.

This feedback shows that the management of invasive alien species is not a cosmetic issue. It determines the ecological continuity of the site, regulatory compliance and, in some cases, the safety of the structure.

2. The Paulownia tree: the perfect example of a “green” promise that backfires

The rapid expansion of Paulownia in France is emblematic of a simplistic ecological discourse. Presented as a "miracle" tree, with rapid growth, carbon capture, and high-value timber production, it is now planted on approximately 5,000 hectares, particularly in Brittany and the Southwest.

The reported data shows a significant gap between promises and reality:

• Asian species introduced on a massive scale for ornamental purposes and then for exploitation;
• reproduction by seeds dispersed by the wind and by suckers, classic heritage of the EEA;
• recognition of its invasive potential by the EPPO;
• high water consumption for the promised yields: up to 120,000 L/ha/year;
• confusion between “sterile” hybrid clones and fertile varieties which are still poorly documented.

This case serves as a reminder that a “green solution” can mask poorly managed ecological risk-taking, especially when it relies more on a marketing narrative than on an independent assessment.

3. WEEE waste: the most underestimated constraint

The conference recalls a legal framework that is often ignored: waste from EEE falls under the general waste regime, with direct responsibility of the producer (article L541-2 of the Environmental Code, ministerial note of November 2, 2018).

Three technical approaches exist:

1. Priority recovery: industrial composting (with temperature control and sorting) or methanization (under strict conditions).
2. Local management: possible but very regulated (drying, mulching, in situ composting).
3. Disposal: incineration or storage, safer but costly, to be reserved for rhizomes or heavily contaminated soils.

Controlling these channels is essential for effectively reducing the risk of dissemination.

4. Digital technology as a sensor, not as a guarantee

The Lucee-TP application, developed by the FNTP and Ecovivo, illustrates an interesting approach: enabling public works companies to detect invasive alien species (IAS) directly in the field via photographic scanning. The tool offers simplified species fact sheets and a PDF report.

But the limitations are explicit:

• incomplete species coverage;
• dependence on image quality;
• expert validation is needed to confirm the identification;
• Reliability varies depending on the context.

Digital technology allows us to capture weak signals, but it does not replace independent expertise on biological risks.

Conclusion: Seriously integrating EEE strengthens the ecological credibility of a project

Feedback from the Seine-Bassée construction site demonstrates that the management of e-waste is not an optional extra. It is a critical link that can tip a project from an “ecological” status to a situation of non-compliance, or even a risk to the structure.

Three key lessons emerge:

• the issue must be addressed from the upstream phases (diagnosis, technical specifications, contracts);
• the approach must include waste management sectors, which are often poorly anticipated;
• Vigilance must be maintained after the work, as EEE frequently reappear during the operational phase.

In a context of rising regulatory requirements, an independent and rigorous assessment becomes essential to distinguish genuine commitments from declarations of intent.