Russian mining giant Norilsk Nickel, hit by a fuel spill at an Arctic power station in May, will spend $600 million by 2030 collecting Soviet-era waste around its Arctic sites, it said on Tuesday.

The spill, which Greenpeace has compared to the 1989 Exxon Valdez oil spill off Alaska, released 21,000 tonnes of diesel from a rusty-looking fuel tank into rivers and soil near the city of Norilsk in Siberia.

“Lessons have been learned from the recent environmental incident,” Nornickel said in a statement. It cleaned up the area after the spill and set aside $2 billion for environmental damage claim by the country’s watchdog which it currently disputes in court.

“A very important strategic focus will be put on the elimination of legacy pollution, including dismantling of abandoned buildings and structures, metal waste management and recycling as well as sanitary cleaning of the territory.”

The legacy waste in the industrial city of Norilsk, built 300 km inside the Arctic Circle, is massive partly due to its history and lack of roads to other parts of the country. Prisoners from Stalin’s labour camps built the first smelter there 85 years ago.

Nornickel’s $600 million programme will target 467 abandoned buildings and structures there in 2021-2030. More than 600,000 tonnes of scrap metal are expected to be collected.

The waste collection will be part of Nornickel’s wider environment investment plans, which target a reduction in sulphur dioxide emissions in the area by 2025.

Its environmental projects and output growth strategy will require more than $27 billion in total within the next 10 years, including $5.5 billion needed for the environment projects. It plans to upgrade 60% of its energy infrastructure by 2030.