Soil remediation of the Seguin Island and Trapèze sites

Soil remediation of the Seguin Island and Trapèze sites


The Renault factories, constructed in 1929 on the Seguin Island in Boulogne-Billancourt (92), stopped operating in 1992. As part of a real-estate redevelopment project on the island, Antea Group was commissioned by Renault for the site soil remediation (116.14 acres) and carried out the following tasks:

  • Comprehensive environmental studies, including detailed historical reviews on each lot;
  • Environmental investigations;
  • Human health risk assessments;
  • Technical specifications for remediation works;
  • Technical and financial supervision of the works;
  • Remediation completion reports;

Assistance in the communication between the project owner and the administration and the developer.


Antea Group defined an investigation strategy approved by the administration:

  • Soil borings till a depth of 8 m bgl and following a 10 m-wide grid;
  • Soil sampling on 2 m-thick layers;
  • Laboratory analytical program based on historical activities;
  • Groundwater investigations;
  • Soil gas investigations;
  • Definition of remediation targets following a health risk-based approach.

Antea Group also defined the works completion control protocols.


The decontamination works involved:

  • 420,000 t of excavated soils,
  • 220,000 t of polluted soils treated on site,
  • 160,000 t of polluted disposed off site,
  • 800,000 t of soils managed.


The residual contamination left in place due to technical constraints amounted to 900 tons, which is less than 0.2 % of the identified contamination.


The closure certificates have been obtained from the administration for the 5 remediation orders.