remediation of a radioactive tailing pond
Detailed description of the Good Practice
The radioactive tailing pond is located in the Ida-Viru county, in the western part of Sillamäe, directly on the coast of Gulf of Finland. In fact, the seaside dam is only 30-50 meters from the waterfront. The depository is located on a territory ca. 50 hectars and contains about 12 million tons of uranium process tailings and oil shale ashes, deposited there since the secrete uranium production factory of the Soviet Union was established in 1948. Research has proved that there exist both direct hazards – constantly spreading pollution, and indirect hazards – the seaside dam of the depository is instable and may break.
The pollution spreads from the depository in three different ways: - rain and water pouring from mainland slowly seep through the mass of tailings and carry nitrogen and dangerous substances(uranium, thorium, barium, strontium) to the sea; - in summer nearly whole surface of the depository is dry causing wind to carry dust from the depository to the surroundings and residental areas of Sillamäe (these are located ca. 1,5 to 2 km); - the depository emanates radioactive gas, radon, which partially spreads over the town as well. In case the seaside embankment breaks, incalculable quantity of dangerous substances may flow into the sea.
The remediation of the project really started when a financing memorandum between the Republic of Estonia and the European Commission was signed in 1999. The Sillamäe tailing pond is only one of the many in Eastern Europe and not by far the largest. In the opinion of European experts, however, the Sillamäe tailing pond is environmentally one of the most dangerous. By completing the project successfully, Sillamäe has become the first environmentally remediated depository of uranium tailings in the whole Eastern and Central Europe.
The good practice is a bout remdiation of a hazardously poisoned tailing pond.
Objectives of the Good Practice
Objectives were to remediate the pond and to prevent the inhabitant from hazardous substances.
Timeframe: start 1999- planned end 2006
Participants of the Good Practice
Wismut GmbH (assessing and reporting)
Target group of the Good Practice
citizens of Sillamäe and surroundings
Funding of the Good Practice
The budget was established at 20 million EUR to be provided by the Estonian Government, EC, governments of Finland, Sweden, Norway and Denmark as well as NEFCO, the Nordic
Environment Finance Corporation.
More Details of the Good Practice
The steps to take:
Long term safety requires that such sites must provide protection for 1, 000 years. Therefore, for remediation artificial materials such as PVC, geotextiles, etc. are not suitable. Reports submitted by Wismut GmbH foresaw the following means:
• Reinforcement of the dam of the depository by building breakwave on the shore and establishing a pile grillage on the area between embankment and the shore;
• Blocking the waters flowing from the mainland by a diaphragm wall;
• Contouring the surface of the depository and covering the depository with a multilayer waterproof cover.
• After remediation the environmental hazards disappear, because:
• The covered depository looks like a hill, covered with vegetation, water can’t get in there: it runs down the slopes without absorption; the surface water discharged from the mainland will be led to the other direction by a trench and diaphragm wall;
• Radioactive dust doesn’t rise from the covered surface;
• Radon is still emanating from the tailings deposit, but it decays before getting on the surface (half-time of radon is approximately 4 days).
• The reinforced concrete pile grillage will guarantee the stability of the dam. Preparations began in autumn 1999 with the liquidation of the oldest depository that consisted of 20,000 cubic metres of clayish radioactive mass. Tailings with high gamma activity were transported into the main depository. International tenderswere held to specialised contractors and the project entered the phase of highvolume
earth-works. Geothechnical investigation of the tailings mass and the dam was conducted 2000. A total of 800, 000 cubic metres of oilshale ash and soil are removed from the area of the future diaphragm wall and from the ash depositories to the tailing pond.
The works of stabilisation of the tailing pond began in May 2001 and lasted for
18 month including construction of access roads, reinforcement of shore, pile grillage,
trench and diaphragm wall. The covering of the tailing pond began in autumn
2001. The remediation project of the Sillamäe radioactive tailing pond was expected to be completed in the second half of 2006.
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Sillamäe LA 21 and envieonmental coordinator
Tel +372 39 25 758
Fax +372 39 25 701
Data sources and references
Baltic Cities Environmental Bulletin 2/2001