In Kristianstad, one of the most polluted areas in southern Sweden has been decontaminated as part of a project to achieve a toxin-free environment. Toxins were reduced by 99.9% and the area is now the development site for a new residential district.
Most countries and cities have areas that are contaminated by substances that are hazardous to wildlife, people and the environment. Toxins in the soil or water often remain from industrial or other activity involving chemicals, typically textile manufacturing, wood impregnation, mining, chemical production, automotive production, pulp and paper and glassworks. Besides posing a threat to health and the environment, such contamination prevents these sites from being used for building, hindering the development of residential areas.
In Sweden, contaminated areas are both investigated and remediated under the coordination of Naturvårdsverket (Swedish Environment Protection Agency) as part of a major project to achieve the national objective of a ‘toxin-free environment’. According to this objective, all sites with very significant or significant risk to human health and the environment (class 1 and 2 contaminated hazard) must be remediated by 2050.
From hazard to housing
One of Sweden’s most polluted areas was a former dry-cleaning site on Bomgatan in Kristianstad, southern Sweden, which posed a very great risk of spreading the highly toxic solvent PCE to groundwater. The remediation of a polluted area of land is often carried out by excavating the contaminated soil and depositing it as landfill. But this is not an optimal method and there’s a great need for alternative methods that are more cost-effective and environmentally sustainable. The project in Kristianstad combined traditional remediation with the innovative in situ thermal desorption (ISTD) method, making it a pioneering project.
Innovative method to remove 99.9% of PCE
The thermal treatment evaporated approximately 1,500 kg of PCE from the soil, 20 metres deep. Using this method, the PCE was captured in active carbon filters and destroyed. The thermal treatment ended in April 2018 and resulted in 99.9% remediation of the contamination, enabling the land to be used to build a new, sustainable residential area.
The responsibility challenge
One of the challenges of ‘old’ contamination areas is the difficulty of following the ‘polluter pays’ principle, i.e. the business or person responsible for the present or past operations that have polluted the site (or in some cases the landowner) is liable for investigation and remediation. In many cases, the pollution happened so long ago that it’s impossible to find the person or business that is liable. Many of the remediation projects in Sweden therefore have to be financed through national funding. Where areas are decontaminated to use the land for housing, the development can sometimes pay for the remediation.
Many organisations and authorities involved
Numerous organisations are engaged in the remediation process in Sweden, from the coordinating governmental authority SEPA to county administrative boards and, at local level, municipalities. The Swedish Geological Survey is also involved in some projects, and the Swedish Geological Institute is responsible for support on technical issues. Other organisations sometimes have a role, including private operators, research institutes and non-profit networks contributing knowledge, experience and resources.