Return to a natural environment after remediation of a former refinery
A refinery in south west NORWAY was dismantled after 35 years
of activity. An important soil remediation program has been
undertaken, as a whole re-conversion of the site is planned.
The pollution was made of different hydrocarbon products (diesel, jet fuels, heavy fuels…) and the concentrations levels rose from 2,000 to 30,000 mg/kg TPH.
The target levels to be reached were determined according to the definition of a Hazard Index calculated in function of risk analysis and the impact of each contaminant on human health.
To have a limited environmental impact, all soil have to be treated on site, that’s means no soil can be treated outside in landfill for example.
Polluted soil to treat
Define a remediation strategy
Based on SUEZ experience, a strategy has been defined including environmental impact and cost effective.
The choice of the treatment method depended on various criteria: decontamination performances, duration, economical parameters.
Biological treatment by “land farming” and by air injection-extraction: the biological treatment technique is based on developing microorganisms bringing about a metabolic degradation in the biodegradable organic molecules.
These reactions correspond to a break in carbonated chains. The residual products are mainly mineral compounds, H20 and CO2, presenting no danger to the environment.
Soil Washing: Soil are treated in mobile units by soil washing using water. This treatment method uses a combination of physical separation methods and chemical treatment to fully segregate the
contamination from the cleaned soil. This method allows the recovery of a large fraction of cleaned sand and debris. The remaining residue contains a high concentration of contamination, which is treated by thermal desorption on-site.
Low Temperature Thermal Desorption: The pollutants released from the soil during incineration are moved into the combustion chamber where they are treated at high temperatures. Before the flue gas enters the chimney, gas treatments take place to respect emissions regulations.
SUEZ performed an on-site treatment of 460,000 tons polluted soils using those 3 combined techniques: the treatment was made in a continuous mode (24 /7) with a plant manager to supervise also the excavation operation to ensure that its progress matched the output of the treatment process.
Working safely with respect for population and environment, whilst delivering high quality work, are guiding principles for our activities.
All our activities take place in compliance with our integrated care system, which is certified according to strict standards.