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5. Reclamation projects

Nuclear Monitor Issue: 
#439-440
Special: Uranium Mining in Europe - The Impacts on Man and Environment
29/09/1995
Article

 

Reclamation Standards


(September 1995) In European countries, there are no legal regulations specific to the management of the uranium mining legacy so far. In Germany, environmental groups called for a reclamation law and the adoption of the US regulations, but the Federal Government refused any such demands [BT1992a], [BT1993a]. Parliamentary initiatives by Greens [BT1992b] and Social Democrats [BT1994] were declined by the Conservative's majority. The Federal Government favours the Canadian approach of site-specific decisions; it has also intervened at the International Atomic Energy Agency (IAEA) against a worldwide adoption of the US regulations [BT1993b].

Correspondingly, a standardized concept for the reclamation tasks to be done in Eastern Germany is lacking. Reclamation action was started without sufficient analysis and consideration of management alternatives. There doesn't even exist a standardized procedure for hazard assessment at the various sites; only gamma radiation is monitored systematically.

According to the German Unification Treaty, the West German radiation protection regulations are not adopted for the East German uranium province, but the GDR regulations remain in force. Thus, an annual dose of 1 mSv (100 mrem) instead of 0.6 mSv (0.3 for the aquatic and 0.3 for the atmospheric pathway) is admissible. The calculation rules of the GDR regulations, moreover, result in much lower radiation doses for a certain amount of activity ingested, and therefore allow for much higher radiation uptake to obtain the same doses [Küppers1991]. The annual dose limit of 1 mSv means that one lifetime incidence of cancer is regarded acceptable per 286 persons concerned.

Several communities and individuals have filed a suit at the Federal Constitutional Court against this provision of the Unification Treaty. The suit has been accepted for decision, but judgement is still pending.

For the reuse of contaminated material and areas, various recommendations have been elaborated by the German Radiation Protection Commission (SSK) [BMU1993]. They are based in principle on an excess annual dose of 1 mSv for the public. But, this limit does not include the dose from drinking water contamination (another 0.5 mSv) [SSK1993t], and from radon in homes. SSK's recommendations are, moreover, based on different calculation rules for the doses resulting from ingestion with food and water, than used in the West German radiation regulations; thus, higher radionuclide uptakes are admissible, until the limit is exceeded [Küppers1994]. For the most problematic issues - the management of the uranium mill tailings and in-situ leaching facilities - there are no recommendations at all.



Reclamation Cost



If the total reclamation cost of DM 13 billion (US$ 9.3 billion) estimated by the German Federal Government for the Wismut sites is attributed to the amount of uranium produced, specific reclamation costs of DM 60 (US$ 43) per kg of uranium produced are obtained. Since the costs for the reclamation of those sites that were returned to the local authorities before 1962, are not included in this amount, the true figure should be even considerably higher. Nevertheless, this cost is already higher than the current world market price for uranium of about US$ 26/kg. On the other hand, it is not yet clear, whether Wismut's reclamation concept can at all be realized as is proposed. Groundwater protection might require much more expensive efforts than proposed so far.

Uranium Mines



Soon after the termination of uranium mining, Wismut started flooding of the deepest parts of its shafts, i.e. the pumps were shut off. Hazardous liquids were removed before flooding, while contaminated equipment remains in place. The rising groundwater level thus reaches the contaminated material. Through the presence of oxygen and water, chemical processes take place, leading to leaching and mobilization of contaminants. Barriers are built at several places in the underground mines to prevent uncontrolled circulation, but there is no complete refill of the mines. A restoration of natural groundwater flow conditions is impossible due to the large system of shafts and galleries. After completion of the flooding, a new geochemical equilibrium can establish, reducing the mobility of contaminants. But it may take decades to reach this state. In the meantime, release of contaminated water must be inhibited, or its treatment prior to release must be assured.

The ramp leading to the bottom of the pit was constructed from material of the Gessental heap leaching pile.



Waste Rock Piles



According to Wismut's reclamation concept, the majority of the waste rock piles in the Thuringian mining district is to be dumped in the open pit of the former Lichtenberg mine; the others are to be protected by covers. After the political changes, Wismut had already started to dump parts of the highly problematic 7 million tonnes Gessental heap leaching pile into the Lichtenberg pit. Due to the high contaminant concentration of this pile, its high pyrite contents, and its leaching by sulfuric acid over decades, a long lasting groundwater contamination must be anticipated after the flooding of the pit.

The liquid hazardous wastes that were dumped after the political changes on the Absetzerhalde pile in Ronneburg, need to be removed and disposed of separately, before this pile can be reclaimed. Wismut wants to build a special toxic waste deposit for this material on its Ronneburg premises. The license for dumping the Absetzerhalde pile in the Lichtenberg pit was issued in March 1995.



Uranium Mills



Wismut plans to release parts of equipment contaminated at levels below SSK recommendations for smelting or reuse. Items of higher contamination are to be dumped in the existing uranium mill tailings ponds.

This mixing of the tailings with metal scrap might result in generation of gases inside the tailings deposits, endangering their safe disposal.



Uranium Mill Tailings



As an immediate measure, Wismut has covered the dry tailings beaches with neutral soil to prevent further blowing of the dry tailings by the wind. Since the ground under the deposits has not yet been investigated in detail, it is not known, whether the deposits can at all be reclaimed in situ. If they would have to be temporarily removed (for installation of a liner) or permanently relocated, then this soil cover would have to be removed again.

With the slurries dumped in the Helmsdorf tailings dam, dehydration tests are being conducted at present. A water treatment plant is being taken into operation at this dam, to allow for the treatment and discharge of the highly contaminated water ponding on the tailings, and of seepage collected.

The uranium mill tailings deposit at the Ellweiler uranium mill in Rhineland-Palatinate was reclaimed by the State after the shut down of the mill at costs of DM 6.9 million (US$ 4.9 million). A few months after the completion of the reclamation work, parts of the cover slid after rainfall in January 1991. The same happened again in January 1995. It is obvious that the present state does not meet the requirements for a long-term disposal, and that a safe confinement of the tailings is impossible in situ, due to the limited space and the immediate neighbourhood of a creek. A new concept must therefore be developed and realized, aiming at the relocation of the deposit.

In France, the "pervious surround disposal" method was used for the first time for the disposal of uranium mill tailings in groundwater at Le Cellier (Lozère). After the shut down of the mine in 1987, 1.1 million tonnes of tailings were dumped in the 105 m deep open pit. The pit is located in granite rock. The tailings were neutralized and dehydrated to 10 % before disposal. The pit bottom and walls were lined with a drainage layer from uncontaminated waste rock before the start of the disposal. From the same material, alternating drainage layers were installed between the tailings being disposed. During the pit filling process, seepage was pumped from the deepest point of the pit, but in the long term, the pit is to be left unattended. The course of the fractures in the rock was investigated to allow for follow-up of eventual seepage. No groundwater contamination outside the site has been detected so far. But the question is, whether this remains true in the long term. As the cover installed on top of the tailings is not impermeable, a fraction of precipitation can infiltrate the tailings. The tailings also contain the mineral pyrite. It must therefore be anticipated that, through the oxygen brought in by precipitation, a continued natural production of sulfuric acid will take place, leading to the destruction of the neutralization performed, and to the mobilization of contaminants. And, the performance of the drainage layer must be questioned in the long term; if it plugs with fine material, it cannot fulfill its function any longer.

In Spain, the uranium mill tailings deposit at Andújar (Andalusia) is at present being reclaimed according to the US regulations, without these regulations being legally in force in Spain [Santiago1994]. This is the first application of these standards in Europe. In addition, groundwater standards were defined for this site. The tailings deposit was operational from 1959 to 1981, comprising a volume of 1 million m3 and covering an area of 9.4 hectares.

In Sweden, the reclamation of the Ranstad uranium mill tailings is being carried out at present. It has a volume of 1 million m3 (1.5 million tonnes) and covers an area of 25 hectares. These tailings have an extraordinarily high concentration of pyrite (FeS2) at 15 %. A cover made from several layers was installed, designed also to prevent access of air to the tailings. The natural generation of acid in the tailings with subsequent mobilization of contaminants is thus intended to be minimized. Seepage is at present being contained and treated, but seepage quality has already improved, and it is hoped that water treatment and further maintenance can soon be abandoned. The total reclamation costs are estimated at US$ 25 million. [Sundblad1994], [Linder1993]



In-Situ Leaching



A problematic matter is the proposed flooding of the Königstein (Saxony) in-situ leaching mine: There are still around 1.8 million m3 of highly contaminated leaching liquid present in the deposit. So far, there are no large-scale proven methods to remove this liquid from the deposit and to inhibit continued leaching of uranium and other contaminants. The impact is rather severe, as the mining activities damaged an aquifer used for the drinking water supply in the Dresden area.

Initially, Wismut also planned to leach those ore blocs that had already been prepared for leaching, before the decision for the shut down of the mine was made. This leaching was intended to remove uranium for its possible groundwater impact. But, expert analysis, untertaken on behalf of the Saxonian Ministry of Environment, showed that the situation would become even worse, since the result would be a geochemical disequilibrium, enhancing the mobilization of many contaminants. The Ministry consequently prohibited this leaching. Wismut then went to the law, but later withdrew the suit.

At present, Wismut plans to flood the Königstein mine (which is an underground mine converted to in-situ leaching in some areas), up to a certain groundwater level, to wash the leaching blocs. The flooding should be halted and the flooding waters be contained and treated, until their contaminant concentrations would only be marginal. It must be anticipated, though, that this procedure might take hundreds of years, as the leaching zone is no longer washed under pressure, unlike during the leaching action.

The situation is even more difficult in the North Bohemian in-situ leaching facility of Stráz pod Ralskem: the goal of restoring groundwater quality to background has been abandoned as unrealistic. Instead, the goal of reducing the contaminant concentrations at least to 100 times drinking water standard has been proposed. But, modeling showed that even this reduced goal would require continued pumping of groundwater for 168 years, and subsequent treatment (at least initially).

The restoration goal for the aquifer located above the leaching zone, and used for drinking water supply, is the drinking water standard. Here, this goal is more realistic, since contaminant concentrations are much lower. This restoration process is already underway with preliminary water treatment. If, however, no adequate solution for the restoration of the leaching zone is found, migration of contaminated liquids from the leaching zone might cause contamination of waters used for drinking water supply.


No European country has promulgated legal regulations for the reclamation of its legacy of uranium mining so far.

The costs for reclamation of the wastes produced from uranium mining and milling exceed by far the current world market price of uranium.

Wismut undertakes several reclamation actions at its sites in Eastern Germany; a fundamental analysis of the problems, the assessment of alternative management options, and a standardized concept are lacking though.

In Western Europe, favourable (Ranstad, Andújar) and questionable (Le Cellier) examples exist.

In Central and Eastern Europe, discussion of the legacy of uranium mining is only beginning.


Related image:
Former open pit mine Lichtenberg, Ronneburg, June 1992