Soil & Sediment Washing

The management of contaminated soils and sediments has gained increasing importance in recent years. Decades of industrial management with a lack of environmental awareness and appropriate regulations have created largely polluted areas requiring urgent environmental attention.

Additionally, the issues concerning the management of sediments resulting from activities involving drainage maintenance and reclamation strongly affect the development of many Italian ports and harbors, some of which are located within the Contaminated Sites of National Interest.

The company 6V Srl is a collaboration between 3V Green Eagle & TREVI to optimize the performance of land reclamation and environmental restoration works mainly through on-site techniques, including the management, treatment and recovery of contaminated soils and sediments - within infrastructural works - land reclamation works and confinement of polluted sites

Contaminated soil and sediment dredged from ports or access channels require specific treatment technologies in order to be re-used in a sustainable way. These treatment technologies often require the following steps:

  • Decontamination
  • Minimization of volumes intended for treatment
  • Maximum product re-use

Dredged Sediment Management Approach:

  • For non-contaminated sediment:
    • Maximize sediment reuse via grain size separation techniques such as sand and gravel recovery (vibro-sieving)
    • Achieve silt geotechnical stabilization for recycle:
      • In line thickening process (centrifuge)
      • In line consolidation process (adding binders)

  • For contaminated sediment:
    • Maximize sediment reuse via grain size separation techniques such as sand and gravel recovery (vibro-sieving)
    • Send the suspension of silt and process water to the TOP® Wet Oxidation treatment plant.

Treatment Plant Capabilities:

3V Green Eagle's treatment plant has the following features:

  • Physical forces wash contaminants and fines from the coarse fraction
  • Piles of coarse-grained material are generated for re-use. A fluid stream containing silt and clay is also produced and requires further handling.
  • The plant handles large fluidized inputs in large amounts (systems designed for 350-400 m3/h input).
  • It works automatically in small spaces.
  • A batch-specific cement grout is injected directly at the centrifuge input. The quantity of binders added is automatically controlled based on sensors that measure the inlet mud flow rate and density.
  • Customization, homogeneity and quick hardening allow for immediate disposal, reuse or recycling without the need for storage or drying.

Technological Applications and References:

In order to thoroughly study and test different problems concerning soil and sediment washing, 3V Green Eagle uses pilot plants. Some interesting tests that were performed for public entities include the following:

  • In 2011, the Surveyor for the Social, Economic and Environmental Emergency who is concerned with the major navigation port canals of the Venice Lagoon (Commissario Delegato per l'Emergenza Socio Economico Ambientale relativa ai Canali Portuali di Grande Navigazione della Laguna di Venezia) has authorized the testing of an innovative process for the treatment of dredged sediments. It also includes the stabilization of the dredged sediment's fine fraction through the continuous injection of cement grout, so as to enhance its mechanical features before the final disposal. The testing procedure consists in draining and subsequently treating 200 m3 of sediments coming from different areas within the canals of Porto Industriale di Marghera. Experimental Design were presented at the 7th International Conference on Contaminated Sediment Remediation in February 2013.

  • In 2013, we conducted a similar case study on the Livorno and La Spezia ports (Italy) commissioned by Sogesid, a company owned by the Italian environmental minister.