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Together with this water, some amounts of slurries were released. The bed of the Vassara river now is covered over a length of at least 7 to 8 km with the white slurry which may impact soil fauna. The Vassara flows into the Lina river. Uno Strömberg of the Länsstyrelsen authority now fears that the reproduction of the salmon may be disturbed. For its development, the salmon roe needs high oxygen concentrations in the water, but these are not warranted due to the slurry. Strömberg anticipates that the slurries will stay in place until next spring. The release of copper into the environment was 23 kg rather than the 6 kg communicated by Boliden earlier. (Dagens Nyheter, Sep 20, 2000)
Around December 4, 2000, Boliden released another 1.5 million cubic meters of water from a settling pond into the environment, in order to decrease the pond water level by 1 meter, to prevent a dam failure. Boliden estimates, that 8 - 10 kg of copper were released with the water. (Dagens Nyheter, Dec 9, 2000)
The public prosecutor for environmental affairs of Luleå has decided to institute a preliminary examination against Boliden. (Dagens Nyheter, Sep 12, 2000)
The public prosecutor for environmental affairs of Luleå has announced to sue Boliden for environmental crimes. The bill of indictment will probably be completed in autumn 2002. (Norra Västerbotten, April 5, 2002)
Aitik is an open pit copper mine and a mill located 60 km north of the Arctic Circle in northern Sweden. The mine is Europe’s largest open pit copper mine. It is in operation since 1968.
It has proven and probable reserves of 213 million tonnes of ore at grades of 0.4% Cu, 0.2 g/t Au, and 3 g/t Ag (Jan. 1, 2000).
The 1999 production amounted to 17.736 million tonnes of ore. The concentrates produced from this ore contained 59,838 tonnes of copper, 40,520 oz of gold, and 2,042,000 oz of silver.
The mine's surface water runoff contained 73 kg of copper and zink in 1998.
At present, the tailings cover an area of 13 square kilometers.
On July 19, 2001, a new crack of 20m length was discovered in a dam at the Aitik mine. (Svenska Dagbladet, July 20, 2001)
On December 8, 2003, a new leakage occured and a limited amount of water spilled from the tailings dam. (Norra Västerbottens Tidning Jan. 22, 2003)
A former Boliden employee is suspected of having committed various crimes in connection with the tailings dam failure. (Norra Västerbottens Tidning Apr. 14, 2005)
Swedish press had reported on October 7, however, that Boliden had admitted that negligence of the company may have been the cause of the dam failure: Boliden's environmental director Lars-Åke Lindahl said to Swedish radio in Norrbotten: "Since these dams are built during a number of years and in various stages, there always is the risk of negligence with one of these stages." (see construction of upstream tailings dams)
The final report was due on November 21, 2000, but the deadline then was extended to March 31, 2001. According to Boliden's Environment, Health and Safety Report 2000, this final report was made public in March 2001.
According to a paper presented by Boliden at a conference in June 2001 (see below), another theory about the cause of the dam failure says that "inner erosion has taken place along the discharge culvert, possibly in combination with openings in the joints between culvert elements and/or collapse of the culvert. Break-in of water and soil to the culvert, probably, has caused a sinkhole in the dam with flow directly from the pond into the culvert. The failure escalated and ended with overtopping of the dam and, eventually, a complete failure."
On October 11, 2000, Länsstyrelsen brought a charge against Boliden for still exceeding the maximum permitted water level in the settling pond. (LN release Oct 11, 2000)
The decision on a possible preferment of a charge against Boliden has been deferred by at least half a year. The regional government had brought a charge against Boliden for not having complied to dam construction regulations and for having exceeded the permissible water level in the impoundment. (Dagens Nyheter June 2, 2001)
On October 8, 2001, Länsstyrelsen released its report on the causes of the dam failure:
Dammhaveriet vid Boliden Mineral AB:s anläggning i Aitik den 8 september 2000, Bedömning av orsakerna till dammhaverietExcerpt from abstract:
> Download full report (1.4M PDF in Swedish, with abstract in English)
"According to CAB's interpretation, based on reviewing of extensive source material, including Boliden's inquiry of what caused the dam failure, most likely the dam failure was caused by bad conditions inside the tailings dam, exacerbated by slightly intensified external influence as high flows and heavy rain.
There have been two main theories. According to these theories the dam has collapsed, either caused by low slope stability due to high pore pressure, or development of a sinkhole through inner erosion, which led to overflowing and completed the dam failure.
A dam failure can occur either by shortcomings in the construction of the dam, unexpected external influence or a combination of these factors. In this case the dam has admittedly been slightly affected by external influence, but still within the limitations the dam should have been designed for. The cause of the dam failure is therefore to be found in bad conditions in the dam or it's foundation-laying. These bad conditions were probably caused by cases of shortcomings in Boliden's own inspection during planing, construction and repairs. Several shortcomings have been detected in these phases of the now failed dam. The monitoring of the dam was inadequate to be able to detect the problems in time to possibly prevent the dam failure. Some conditions which now is regarded as shortcomings can still be explained by previously valid guidelines for own inspection and other established practice regarding construction of for example water outlets."
(CAB = county administration board / Länsstyrelsen)
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