Old landfill discovered during renovation at Sanna Park in Helsinki

During renovation work at Sanna Park in West Pasila, Helsinki, an unexpected discovery was made: an old landfill emerged from the soil. Among the debris, various waste materials including pots, bent metal, and plastic bags were found, revealing what project manager Tea Karjalainen described as a mix of household waste and hazardous materials, including an oil drum uncovered this week.

The presence of this buried waste is alarming, as Sanna Park has been a playground for children since the 1980s. Karjalainen noted that none of the project team members had prior knowledge of the landfill’s existence. With children playing above this historically contaminated site, the renovation project now includes soil remediation efforts.

Experts from the City of Helsinki’s construction services and consulting firms are compiling a report on the landfill’s materials to share with environmental professionals. Until this analysis is complete, it’s difficult to assess whether the children have been adversely affected by the waste. However, Karjalainen reassured that the children were not in close contact with the contaminated materials, as there was a significant amount of cover soil and a splash pad structure on top of the landfill.

Although Helsinki’s old landfills may no longer be marked on current maps, contaminated soil is still a common finding in construction sites across the city. Recent projects in Vallilan, Leivosen, and Perhosniitty parks have also revealed unpleasant surprises. The presence of discolored soil indicates the burial of unwanted materials, including metals and other hazardous compounds, highlighting the stark difference in waste management practices from a few decades ago.

Karjalainen hopes that these findings will only delay the completion of Sanna Park renovation by about a month, pushing it to July 2025.