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The biggest semi-coke mountains of Estonia do not pollute the environment anymore


Kohtla-Järve and Kiviõli semi-coke mountains that endangered the environment of Ida-Virumaa for a long time are now properly closed and do not pose a threat to the environment.

“The closing of the big semi-coke mountains of Ida-Virumaa is an example of how costly in terms of time and money it is to improve the nature-ignoring decisions that were once made. The semi-coke mountains have been dangerous for both human health and the environment. Poisonous gases and a variety of contaminants were emitted into surface and groundwater from them,” the Minister of the Environment Mati Raidma said.

Both Kiviõli and Kohtla-Järve semi-coke landfills were transformed during the works and the sides of the mountains were flattened. In order to avoid pollutants from coming into contact with groundwater or surface water, it was required to ensure the water-tightness of the semi-coke mountain. First, the surfaces were covered with bentonite clay mats, then with drainage mats and finally with coating, which was fresh semi-coke in Kohtla-Järve and mine waste in Kiviõli. Finally, lawn was smothered on the mountain slopes and birch saplings were planted. Additionally, the pitch waste lakes that had formed as a result of the manufacturing of oil were closed at the site of both semi-coke landfills.

“Such quite specific works were made even complicated by the fact that the majority of the work had to be carried out on the slopes with high angle. In turn, the burning brands that had emerged inside the mountain at an earlier time caused problems and in order to eliminate these, studies had to be carried out first and then a diverse technical solution developed,” Project Manager of Merko Eesti AS Tarmo Sinisaar, who managed the works, said.

The cost of the project of closing Kiviõli semi-coke landfill was 5.58 million euros and the closing works were carried out by Skanska EMV AS. The cost of the project of closing Kohtla-Järve semi-coke landfill was over 36 million euros and the closing works were carried out by a consortium in cooperation with its leading partner Merko Ehitus Eesti AS. Both projects were fully financed from the European Union Cohesion Fund.

Since 1938, approximately 73 million tonnes of semi-coke and nearly 100,000 tonnes of pitch waste were landfilled in Kohtla-Järve semi-coke landfill. Prior to closing, Kohtla-Järve semi-coke landfill was the highest point with nearly 170 metres above the sea level on a total area of nearly 214 hectares. Over 15 million tonnes of waste have been landfilled in Kiviõli semi-coke landfill on a total area of nearly 47 hectares.

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