Industrial site depollution references

Discharge rehabilitation - FFM and PEM examples

• “In situ” treatment of polluted soils and lagoons: Example of the rehabilitation of a 28,700 m3 deposit of acid stripping residues by in situ stabilisation on the FFM La Longueville site.

  The works have been undertaken as follows:

  1. Acid water extraction and treatment (by addition of specific reagents) with the aim of neutralizing then and making them pelletable,
  2. Muddy or crystallized residue screening and treatment (according to stabilisation formulations produced by INERTEC),
  3. Return to the lagoon by successive compacted layers.
  
  Finally, site redevelopment was completed by the addition of natural material on the surface.

• On site treatment and storage: Example of 100,000 t of arsenic contaminated residues on an internal Pechiney ElectroMétallurgie deposit.

  Several simultaneous problems:
  Site access, mechanical stability, chemical stability (increase in the solubility of the arsenic related to the presence of strongly basic soda muds), risk during operations (storage of dangerous to handle NaK barrels having unknown exact position).
  
  Implementation of work:

  1. Excavation of residues by successive vertical bands, from top to bottom, working upwards from downstream to upstream of the discharge,
  2. Stabilisation in a unit installed on the site,
  3. Replacement using a geometry guaranteeing the site stability, the solidification taking place in situ (initiated downstream of the site, then continued through the refuse).
  Results:
  All the operations were performed using two shifts, at an average rate of the order of 400 tonnes of residues per day. The rehabilitation of the site, from the initial layout works, was carried out in a little over three years, half being devoted to preliminary studies and to the installation of the resources and equipment needed for the work.
  

These rehabilitation works allowed physically and chemically stable sites to be restored and integrated into their environment without impact on the surrounding environment.

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