Restoration of contaminated soil and landfill sites

The most significant contaminated soil restoration sites managed by the City were the Verkkosaari and Vilhonvuorenkatu as well as Työpajanpiha sites. There were also other large restoration sites in the Jokeri Light Rail construction area and the construction areas in Keski-Pasila and Jätkäsaari. In addition to the large sites, several individual small sites were inspected and restored in 2020. Soil was restored at a total of approximately 67 different restoration sites.

The soil restoration was usually carried out during the other construction work in the areas. The soil condition database created by the Ministry of the Environment features the details of 887 areas in Helsinki where research has shown the soil to be contaminated, where the soil has been assessed as being potentially contaminated or where the soil has been restored.

Former landfill sites in Helsinki are restored pursuant to environmental protection legislation. The restoration of the Vuosaari landfill site will conclude in 2021, and the City is preparing to restore the Iso-Huopalahti landfill site in the coming years.

Soil was decontaminated in the same way as in previous years, primarily by excavating the soil containing harmful substances and transporting it elsewhere for appropriate treatment. Soil was also restored by isolating the contaminated soil on site. Below is an overview of how the contaminated soil was transported for treatment or final disposal in Helsinki in 2017–2020.

The total amount of soil transported for treatment or final disposal in 2020 was approximately 298,800 tonnes, which is approximately 169 per cent more than the previous year. The costs generated by the restoration of contaminated areas and landfill sites decreased slightly from the previous year.

In 2020, 1,476,500 tonnes of uncontaminated excavated earth and aggregate were used at public construction sites. 161,500 tonnes of uncontaminated excavated earth were delivered to external recipients.

Table 8. The contaminated soil transported for treatment or final disposal in Helsinki, as well as the costs incurred by the City from the restoration of contaminated soil and landfills in 2017–2020.