Court orders Terrafame to add mineral seal layer to mine waste cover

The Vaasa Administrative Court has revised the environmental permit for Terrafame’s side rock closure structures, requiring the company to add a mineral sealing layer such as a bentonite mat or compacted fine-grained till to the KL1 area.

The ruling follows appeals from the Finnish Association for Nature Conservation’s Kainuu branch and four other organisations against the permit issued last year, which governed how Terrafame must cover side rock—a byproduct of mining that, when exposed to water and oxygen, generates acidic, environmentally harmful leachate.

Terrafame’s sustainability director Veli-Matti Hilla said the company does not consider the mineral sealing layer necessary, arguing that structural solutions should be based on research and testing rather than added as a precaution. The firm is now assessing whether to appeal the decision to the Supreme Administrative Court. Appeals are possible until 13 August.

Under its main mining permit, Terrafame is allowed to extract up to 18 million tonnes of ore annually, with side rock extraction capped at an average of 35 million tonnes per year, though up to 45 million tonnes is permitted if needed.