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The conference addressed scientists and engineers working in the mining industry, and the book is also aimed at scientists interested in uranium in groundwater, water-works managers and political decision-makers. The focus is on uranium mining and processing sites, mining sites such as phosphate mines that have considerable amounts of by-product uranium and radionuclides, abandoned mines, clean-up measures, natural attenuation, monitoring, modelling techniques and risk assessment. Characterisation, monitoring and remediation topics include radionuclides in agricultural soils, electrophoretic characterisation of Th in humic acid solutions, field immunosensors, a natural analogue site at Heselbach, depleted U chemo- and radiotoxicity, U and Cd stress in Phaseolus vulgaris, biotransformation of U complexed with organic ligands, bacterial changes with U(VI), sorption mechanisms, reactive transport in porous media, modelling waste-water discharge, As removal, U solubilisation, U phytoavailability, Portuguese U accumulator plants, N2 soil treatment to facilitate phytoextraction of heavy metals, radiophytoremediation in south Bohemia, P influence on localising U in roots, hydrogeology of Nubian sandstone, radionuclide data for geothermal prospecting in Saxony, contaminated sediments in the Elbe and Mulde basin, U isotope fractionation for characterising groundwater systems, GPS- based Ra/U gamma scanning, radioactive groundwater contamination at Semipalatinsk, U isotopes in lake sediments, origin of high U-234/U-238 ratio in post-permafrost aquifers, U in acidic lakes and groundwater of Lower Lusatia, U concentration changes in the Weisse Elster River with Wismut remediation, and factors affecting U availability to plants., The conference addressed scientists and engineers working in the mining industry, and the book is also aimed at scientists interested in uranium in groundwater, water-works managers and political decision-makers. The focus is on uranium mining and processing sites, mining sites such as phosphate mines that have considerable amounts of by-product uranium and radionuclides, abandoned mines, clean-up measures, natural attenuation, monitoring, modelling techniques and risk assessment. Characterisation, monitoring and remediation topics include radionuclides in agricultural soils, electrophoretic characterisation of Th in humic acid solutions, field immunosensors, a natural analogue site at Heselbach, depleted U chemo- and radiotoxicity, U and Cd stress in Phaseolus vulgaris, biotransformation of U complexed with organic ligands, bacterial changes with U(VI), sorption mechanisms, reactive transport in porous media, modelling waste-water discharge, As removal, U solubilisation, U phytoavailability, Portuguese U accumulator plants, N2 soil treatment to facilitate phytoextraction of heavy metals, radiophytoremediation in south Bohemia, P influence on localising U in roots, hydrogeology of Nubian sandstone, radionuclide data for geothermal prospecting in Saxony, contaminated sediments in the Elbe and Mulde basin, U isotope fractionation for characterising groundwater systems, GPS- based Ra/U gamma scanning, radioactive groundwater contamination at Semipalatinsk, U isotopes in lake sediments, origin of high U-234/U-238 ratio in post-permafrost aquifers, U in acidic lakes and groundwater of Lower Lusatia, U concentration changes in the Weisse Elster River with Wismut remediation, and factors affecting U availability to plants.

Elemental iron and hydroxyapatite were evaluated as reactive materials in permeable reactive barriers for uranium remediation. Following laboratory experiments, a pilot-scale Fe(0) reactive barrier was installed in Pecs, southern Hungary, where the former U mine and processing site has around 19 300 000 t waste rock and 27 500 000 t accumulated tailings, containing a total of 2 300 t U. Results from 2.5 years of operation show that the permanent reactive barrier has a considerable influence on groundwater composition, uranium contents having decreased from 900 to less than 10 micrograms/l and total dissolved solids from 1 000 to 500 mg/l., Elemental iron and hydroxyapatite were evaluated as reactive materials in permeable reactive barriers for uranium remediation. Following laboratory experiments, a pilot-scale Fe(0) reactive barrier was installed in Pecs, southern Hungary, where the former U mine and processing site has around 19 300 000 t waste rock and 27 500 000 t accumulated tailings, containing a total of 2 300 t U. Results from 2.5 years of operation show that the permanent reactive barrier has a considerable influence on groundwater composition, uranium contents having decreased from 900 to less than 10 micrograms/l and total dissolved solids from 1 000 to 500 mg/l.

Results are presented from a survey of the ability of selected tree and grass species, notably pine trees Pinus sylvestris and P. nigra, to accumulate uranium, radium and concomitant heavy metals from rock dumps consisting mainly of clay schists, granosyenites and quartz, in the Buhovo uranium mining area of Bulgaria. It was established that bioaccumulation of radionuclides in the tree and grass vegetation depends mainly on radionuclide content in the substrate, intensity of volatilisation and soil texture. Accumulation in the leaf mass is more intensive for 226Ra than for 238U. In the first years, growth is significantly inhibited for both white and black pines, but the vegetation later adapts to the conditions and grows sufficiently. Treating the substrates with sorbents containing organic substances and clay leads to a strong reduction in the bioaccumulation of both 226Ra and 238U., Results are presented from a survey of the ability of selected tree and grass species, notably pine trees Pinus sylvestris and P. nigra, to accumulate uranium, radium and concomitant heavy metals from rock dumps consisting mainly of clay schists, granosyenites and quartz, in the Buhovo uranium mining area of Bulgaria. It was established that bioaccumulation of radionuclides in the tree and grass vegetation depends mainly on radionuclide content in the substrate, intensity of volatilisation and soil texture. Accumulation in the leaf mass is more intensive for 226Ra than for 238U. In the first years, growth is significantly inhibited for both white and black pines, but the vegetation later adapts to the conditions and grows sufficiently. Treating the substrates with sorbents containing organic substances and clay leads to a strong reduction in the bioaccumulation of both 226Ra and 238U.

The legacy of uranium mining in East Germany included c.577 ha of ponds containing about 154 000 000 m3 of tailings. Remediation started in 1990 with protective measures against active risks, environmental investigations and development of the first site-specific remediation concepts. WISMUT then decided to prepare for dry decommissioning in situ of all the tailings ponds, using the following basic steps: expulsion of pond water and seepage catchment, including treatment of the water; interim covering of the exposed tailings surfaces, including dewatering of unconsolidated fine slimes by technical means; re-contouring of dams and ponds, and final covering including landscaping and revegetation. The development of these procedures and design of large pond decommissioning is discussed., The legacy of uranium mining in East Germany included c.577 ha of ponds containing about 154 000 000 m3 of tailings. Remediation started in 1990 with protective measures against active risks, environmental investigations and development of the first site-specific remediation concepts. WISMUT then decided to prepare for dry decommissioning in situ of all the tailings ponds, using the following basic steps: expulsion of pond water and seepage catchment, including treatment of the water; interim covering of the exposed tailings surfaces, including dewatering of unconsolidated fine slimes by technical means; re-contouring of dams and ponds, and final covering including landscaping and revegetation. The development of these procedures and design of large pond decommissioning is discussed.

Data are presented for dissolved and total uranium concentrations in the German river after the 2002 flood event, at flood in spring 2003 and during extreme low water in 2003; data from several Saale river tributaries are also evaluated. The results reveal that there is still potential for pollution in the Mansfelder Land copper-schist area, requiring the development of remediation stratgegies. U concentrations in the Salza and Schlenze tributaries, that drain the Mansfeld area and in particular receive output from the Schlusselstollen drainage gallery, exceeded those from the Weisse Elster river, which is influenced by former mines in the Gera-Ronneburg district., Data are presented for dissolved and total uranium concentrations in the German river after the 2002 flood event, at flood in spring 2003 and during extreme low water in 2003; data from several Saale river tributaries are also evaluated. The results reveal that there is still potential for pollution in the Mansfelder Land copper-schist area, requiring the development of remediation stratgegies. U concentrations in the Salza and Schlenze tributaries, that drain the Mansfeld area and in particular receive output from the Schlusselstollen drainage gallery, exceeded those from the Weisse Elster river, which is influenced by former mines in the Gera-Ronneburg district.

Analysis of the risks associated with tailings sites in the Min-Kush area showed that they all have associated radiological and stability hazards. The Tuyuk-Su tailings sites in particular call for remediation according to international standards to reduce radiation exposure, the release of radionuclies and chemicals, and the risk of structural failure and long-term erosion. The high risk of the man-made structures in the narrow, V-shaped mountain valley failing by earthquake, landslide, mudflow effects and groundwater flow through the tailing mass poses a stability hazard that cannot be substantially reduced by maintenance of by-pass and run-off collection channels, requiring instead removal of the tailings to a less risky site. Two suitable alternative sites have been identified; after relocation and decommissioning, monitoring of air and water pathways will need to continue for some time., Analysis of the risks associated with tailings sites in the Min-Kush area showed that they all have associated radiological and stability hazards. The Tuyuk-Su tailings sites in particular call for remediation according to international standards to reduce radiation exposure, the release of radionuclies and chemicals, and the risk of structural failure and long-term erosion. The high risk of the man-made structures in the narrow, V-shaped mountain valley failing by earthquake, landslide, mudflow effects and groundwater flow through the tailing mass poses a stability hazard that cannot be substantially reduced by maintenance of by-pass and run-off collection channels, requiring instead removal of the tailings to a less risky site. Two suitable alternative sites have been identified; after relocation and decommissioning, monitoring of air and water pathways will need to continue for some time.

Uranium ores at the Saskatchewan mine, in the Athabasca basin, can produce up to 700 mg/l As and 500 mg/l Ni in spent leaching solutions of pH less than 1.5. Prior to neutralisation, if necessary, feric sulphate is added to tailings slurries to increase their Fe/As molar ratio to greater than 3; the slurries are then neutralised with lime to pH 4 and subsequently to pH 7-8. After neutralisation, As and Ni concentrations average less than 1 mg/l. Solids from bench-scale experiments demonstrate that As is associated primarily with scorodite and annabergite, with small amounts adsorbed on or co-precipitated with ferrihydrite., Uranium ores at the Saskatchewan mine, in the Athabasca basin, can produce up to 700 mg/l As and 500 mg/l Ni in spent leaching solutions of pH less than 1.5. Prior to neutralisation, if necessary, feric sulphate is added to tailings slurries to increase their Fe/As molar ratio to greater than 3; the slurries are then neutralised with lime to pH 4 and subsequently to pH 7-8. After neutralisation, As and Ni concentrations average less than 1 mg/l. Solids from bench-scale experiments demonstrate that As is associated primarily with scorodite and annabergite, with small amounts adsorbed on or co-precipitated with ferrihydrite.

Moderately acidic in-situ leaching is the best technology for minimising surface disturbance and Beverley, in South Australia, is the most technologically advanced ISL mine in the world. Minimal surface infrastructure includes only a processing plant, rather like a water treatment plant, plus small wellfield areas requiring wells, pumps and small pumping huts. The hydrology and mineralogy of the area is discussed and an overview given of the leaching and subsequent processing by ion exchange. The optimised flowsheet and various wellfield patterns are illustrated, the water balance and control described and further initiatives listed., Moderately acidic in-situ leaching is the best technology for minimising surface disturbance and Beverley, in South Australia, is the most technologically advanced ISL mine in the world. Minimal surface infrastructure includes only a processing plant, rather like a water treatment plant, plus small wellfield areas requiring wells, pumps and small pumping huts. The hydrology and mineralogy of the area is discussed and an overview given of the leaching and subsequent processing by ion exchange. The optimised flowsheet and various wellfield patterns are illustrated, the water balance and control described and further initiatives listed.

A pilot-scale constructed wetland, consisting of four basins and one lagoon, was planned, built and operated to treat 5 m3/h of seepage water at the German uranium mine site. The feasibility of the system was proven and the long-term stability and robustness of such passive treatment systems demonstrated for operation during long periods of frost, under increased hydraulic load and under high carbon loading. A tracer was used to test the hydraulic characteristics of the basin. Control of the wetland is very complex, because of the different redox conditions needed for aerobic removal of As and anaerobic removal of U., A pilot-scale constructed wetland, consisting of four basins and one lagoon, was planned, built and operated to treat 5 m3/h of seepage water at the German uranium mine site. The feasibility of the system was proven and the long-term stability and robustness of such passive treatment systems demonstrated for operation during long periods of frost, under increased hydraulic load and under high carbon loading. A tracer was used to test the hydraulic characteristics of the basin. Control of the wetland is very complex, because of the different redox conditions needed for aerobic removal of As and anaerobic removal of U.

Pit water containing 3 500 micrgrams/l U, from the SanRafael uranium mine, was applied to soil columns in a short-term experiment to evaluate U retention in soils. Disposal of water from the flooded open pit to the soil is one of a number of alternatives under consideration to mitigate the risk of contaminated water overflowing from the pit into the water- courses and to allow for possible drainage so that mining can be re- started. The mine soil was coarse-textured, with pH 7.7 and a caarbonate content of 6%, which may favour the formation of uranyl carbonates. Triple superphosphate and ground plant material were added as amendments to reduce U mobility through the soil, and plants were also sown to study their effect on U leaching. After six weeks of irrigation, more than 99% of the applied 11 042 micrograms U had been retained by the soil. Plant growth increased U mobility but also reduced leachate volumes through evapotranspiration. Superphosphate increased plant biomass, reducing the mass of U leached, whereas ground plant material enhanced the leaching of U. As the U concentrations in most of the leachates, especially where plants were present, were above recommended critical values for drinking water and the mass of U in the soil would be a persistent threat to the food chain, irrigation in open systems would only be acceptable after treatment of the pit water to reduce U concentrations., Pit water containing 3 500 micrgrams/l U, from the SanRafael uranium mine, was applied to soil columns in a short-term experiment to evaluate U retention in soils. Disposal of water from the flooded open pit to the soil is one of a number of alternatives under consideration to mitigate the risk of contaminated water overflowing from the pit into the water- courses and to allow for possible drainage so that mining can be re- started. The mine soil was coarse-textured, with pH 7.7 and a caarbonate content of 6%, which may favour the formation of uranyl carbonates. Triple superphosphate and ground plant material were added as amendments to reduce U mobility through the soil, and plants were also sown to study their effect on U leaching. After six weeks of irrigation, more than 99% of the applied 11 042 micrograms U had been retained by the soil. Plant growth increased U mobility but also reduced leachate volumes through evapotranspiration. Superphosphate increased plant biomass, reducing the mass of U leached, whereas ground plant material enhanced the leaching of U. As the U concentrations in most of the leachates, especially where plants were present, were above recommended critical values for drinking water and the mass of U in the soil would be a persistent threat to the food chain, irrigation in open systems would only be acceptable after treatment of the pit water to reduce U concentrations.

A dynamic compartmental model has been developed to combine solute transport in double-porosity media with geochemistry, using the US Geological Survey's PHREEQC code to describe both kinetics and thermodynamics. Among other applicationa, the model has been used to simulate quite different real-world scenarios related to uranium mining. In the case of acid in-situ leaching at Beverley mine in South Australia, the model was adapted to optimising wellfield operation and uranium processing under various orebody conditions. The leaching dynamics was first studied within a simple analytical mode for a single wellfield of 28 injection and 14 extraction wells; this mathematical description is presented and the numerical model calculations for cycle operation are discussed, including the incorporation of dissolution kinetics for coffinite and other primary silicate minerals as well as taking account of chemical equilibrium with secondary minerals such as gypsum, hydroxides and amorphous silica. The second case study is of the use of the model to simulate remediation, in the flooding of the deep Konigstein uranium mine in Saxony. The compartments in the model included 18 mine workings and the 7 sandstone pillars between the workings and the control tunnel, where water was collected and pumped to the surface for treatment; in each compartment the geochemical mass transformations of leaching and flushing were described with reference to two subspaces, the pore space and the mine void., A dynamic compartmental model has been developed to combine solute transport in double-porosity media with geochemistry, using the US Geological Survey's PHREEQC code to describe both kinetics and thermodynamics. Among other applicationa, the model has been used to simulate quite different real-world scenarios related to uranium mining. In the case of acid in-situ leaching at Beverley mine in South Australia, the model was adapted to optimising wellfield operation and uranium processing under various orebody conditions. The leaching dynamics was first studied within a simple analytical mode for a single wellfield of 28 injection and 14 extraction wells; this mathematical description is presented and the numerical model calculations for cycle operation are discussed, including the incorporation of dissolution kinetics for coffinite and other primary silicate minerals as well as taking account of chemical equilibrium with secondary minerals such as gypsum, hydroxides and amorphous silica. The second case study is of the use of the model to simulate remediation, in the flooding of the deep Konigstein uranium mine in Saxony. The compartments in the model included 18 mine workings and the 7 sandstone pillars between the workings and the control tunnel, where water was collected and pumped to the surface for treatment; in each compartment the geochemical mass transformations of leaching and flushing were described with reference to two subspaces, the pore space and the mine void.

A detailed examination of tailings cores and pore waters, kinetic column test work and geochemical modelling was combined with results from earlier studies to examine the ke processes governing the geochemical stability of tailings from the Ranger mine in Australia. It was demonstrated that the solid-state speciation and mobility of metals and radionuclides in the tailings pile are governed by the processes of oxidative dissolution of sulphide minerals, weathering of phyllosilicates and organic matter diagenesis. These mechanisms will need to be taken into account in the design, management and closure of the final tailings repositories at the Ranger mine., A detailed examination of tailings cores and pore waters, kinetic column test work and geochemical modelling was combined with results from earlier studies to examine the ke processes governing the geochemical stability of tailings from the Ranger mine in Australia. It was demonstrated that the solid-state speciation and mobility of metals and radionuclides in the tailings pile are governed by the processes of oxidative dissolution of sulphide minerals, weathering of phyllosilicates and organic matter diagenesis. These mechanisms will need to be taken into account in the design, management and closure of the final tailings repositories at the Ranger mine.

Uranium release from and uptake on material in waste pile No.66 at Schlema-Alberoda in Saxony, Germany, was studied by both static batch and dynamic column experiments, with the aim of obtaining inpuit data for modelling U migration in the pile. Most of the experiments were carried out by radiotracer methods, using U-233 as tge label. An ambiguous influence of humic acid on U migration was observed at acid concentrations of 10 and 50 mg/l. The column elution experiments were modelled using the PHREEQC code, allowing the kinetic character of the desorption process to be respected., Uranium release from and uptake on material in waste pile No.66 at Schlema-Alberoda in Saxony, Germany, was studied by both static batch and dynamic column experiments, with the aim of obtaining inpuit data for modelling U migration in the pile. Most of the experiments were carried out by radiotracer methods, using U-233 as tge label. An ambiguous influence of humic acid on U migration was observed at acid concentrations of 10 and 50 mg/l. The column elution experiments were modelled using the PHREEQC code, allowing the kinetic character of the desorption process to be respected.

Forecasting the migration of an in-situ leach solution in the regional groundwater flow requires account to be taken of chemical reactions in the system of the acid solution and subsurface medium. A Eulerian approach to their calculation leads to significant numerical dispersion, avoided by solving two independent passive mass transport problems. The final solution, a geometrical intersection of passive solutions, shows that the maximum distance of propagation does not exceed 700-800 m over 400 years, during which time total neutralisation of the acid should have occurred. There is no risk of contamination to groundwater used as a water supply, because of the depth of the uranium deposits., Forecasting the migration of an in-situ leach solution in the regional groundwater flow requires account to be taken of chemical reactions in the system of the acid solution and subsurface medium. A Eulerian approach to their calculation leads to significant numerical dispersion, avoided by solving two independent passive mass transport problems. The final solution, a geometrical intersection of passive solutions, shows that the maximum distance of propagation does not exceed 700-800 m over 400 years, during which time total neutralisation of the acid should have occurred. There is no risk of contamination to groundwater used as a water supply, because of the depth of the uranium deposits.

The German tailings investigated had been buried for 30 years under mine and construction debris. Selective sequential chemical extractions, bulk L(III)-edge X-ray absorption fine structure (EXAFS) spectroscopy and synchotron micro-X-ray fluorescence (XRF) and micro-X-ray diffraction (XRD) revealed two major U pools. The first, with a relatively high potential mobility, was identified as U(VI) sorbed to layer sillicates by inner-sphere complexing; the second was represented by the relatively insoluble U(IV) minerals pitchblende and coffinite, and by the U(VI) solids uranyl hydroxide and vanuralite. Distribution between the two pools seemed to be controlled by pH and evidence was found for reductive precipitation of uraninite., The German tailings investigated had been buried for 30 years under mine and construction debris. Selective sequential chemical extractions, bulk L(III)-edge X-ray absorption fine structure (EXAFS) spectroscopy and synchotron micro-X-ray fluorescence (XRF) and micro-X-ray diffraction (XRD) revealed two major U pools. The first, with a relatively high potential mobility, was identified as U(VI) sorbed to layer sillicates by inner-sphere complexing; the second was represented by the relatively insoluble U(IV) minerals pitchblende and coffinite, and by the U(VI) solids uranyl hydroxide and vanuralite. Distribution between the two pools seemed to be controlled by pH and evidence was found for reductive precipitation of uraninite.

A technique known as Equilibrium Partitionijng in Closed Systems, EPICS, was used to develop a quantification method that employs a gentle leaching solution identical to the neutralised raffinate that contacts the tailings, except with regard to As concentration. Prior to implementation, the experimental design and mathematical approach were verified in geochemical models using the PHREEQC program. Laboratory experiments on tailings from the Athabasca basin of northern Saskatchewan demonstrated that the amount of As that could be readily released to pore watersis about 0.2% of the total in the tailings., A technique known as Equilibrium Partitionijng in Closed Systems, EPICS, was used to develop a quantification method that employs a gentle leaching solution identical to the neutralised raffinate that contacts the tailings, except with regard to As concentration. Prior to implementation, the experimental design and mathematical approach were verified in geochemical models using the PHREEQC program. Laboratory experiments on tailings from the Athabasca basin of northern Saskatchewan demonstrated that the amount of As that could be readily released to pore watersis about 0.2% of the total in the tailings.

Mean uranium concentrations between 6 and 149 mg/kg were found in P- containing mineral fertilisers whereas mean concentrations in fertilisers without P were less than 1.3 mg/kg and in farmyard manures no more than 2. 6 mg/kg. As a consequence, an average P dressing of 22 kg/ha wouild charge the soil with up to 17-61 g/ha U when addced as mineral fertiliser but less than 10 g/ha when given as farmyard manure or slurry. Expewcted U uptake by crops is less than 1 g/ha., Mean uranium concentrations between 6 and 149 mg/kg were found in P- containing mineral fertilisers whereas mean concentrations in fertilisers without P were less than 1.3 mg/kg and in farmyard manures no more than 2. 6 mg/kg. As a consequence, an average P dressing of 22 kg/ha wouild charge the soil with up to 17-61 g/ha U when addced as mineral fertiliser but less than 10 g/ha when given as farmyard manure or slurry. Expewcted U uptake by crops is less than 1 g/ha.

There is good potential for unconventional low-grade but moderate- to large-scale U deposits, such as those dominated by uraniferous thorianite, the high U and Th concentrations associated with alkaline magmatic systems and hosted by rare-earth phosphates, or the unaltered basement rocks that contain up to 60% of the U in the largest deposit systems. Exploration and identification of primary and secondary U and Th enrichment is greatly facilitated by the micro-energy dispersive X-ray diffraction techique that allows high in-situ resolution and simultaneous determination of a number of elements, combined with minimal sample preparation effort so that contamination is avoided. The project described was aimed at localising U mineralisation and siting U minerals in ores from Witwatersrand Au, Vergenoeg Fe-F and Palabora Cu deposits, which contained uraninite, uraniferous monazite and uranothorite respectively. Besides U and Th mineral samples, samples hosting U and Th concentrations of unknown distribution were investigated. It was concluded that in-situ micro-EDXRF analysis is a suitable, fast and valid technique for localising U and Th mineralisation as well as low-grade U- and Th-bearing phases over a large sample volume while simultaneously recording other elements., There is good potential for unconventional low-grade but moderate- to large-scale U deposits, such as those dominated by uraniferous thorianite, the high U and Th concentrations associated with alkaline magmatic systems and hosted by rare-earth phosphates, or the unaltered basement rocks that contain up to 60% of the U in the largest deposit systems. Exploration and identification of primary and secondary U and Th enrichment is greatly facilitated by the micro-energy dispersive X-ray diffraction techique that allows high in-situ resolution and simultaneous determination of a number of elements, combined with minimal sample preparation effort so that contamination is avoided. The project described was aimed at localising U mineralisation and siting U minerals in ores from Witwatersrand Au, Vergenoeg Fe-F and Palabora Cu deposits, which contained uraninite, uraniferous monazite and uranothorite respectively. Besides U and Th mineral samples, samples hosting U and Th concentrations of unknown distribution were investigated. It was concluded that in-situ micro-EDXRF analysis is a suitable, fast and valid technique for localising U and Th mineralisation as well as low-grade U- and Th-bearing phases over a large sample volume while simultaneously recording other elements.

Passive control measures such as earth covers protected by rock are less effective in protecting uranium tailings from erosion and leaching in mountainous terrains with high rainfall. A case study of tailings from the former East German Schneckenstein uranium processing plant, at an altitude of 740-815 m in the Boda valley in Saxony, shows that the deposited U and other toxic elements have the potential to contrinue to contaminate the downstream environment, as they have already done, for thousands or tens of thousands of years. Safeguarding the tailings is possible for a few decades but much harder in the ong term. As natural attenuation is unlikely, it must either be enhanced or active measures taken. The advantages and disadvantages of various options are discussed: transferring and burying the tailings, perhaps combined with reprocsesing; coating the minerals to prevent oxidation, possibly by CO2 injection; and capping with chemically reactive material that will percolate into the tailings or maintain reducing conditions., Passive control measures such as earth covers protected by rock are less effective in protecting uranium tailings from erosion and leaching in mountainous terrains with high rainfall. A case study of tailings from the former East German Schneckenstein uranium processing plant, at an altitude of 740-815 m in the Boda valley in Saxony, shows that the deposited U and other toxic elements have the potential to contrinue to contaminate the downstream environment, as they have already done, for thousands or tens of thousands of years. Safeguarding the tailings is possible for a few decades but much harder in the ong term. As natural attenuation is unlikely, it must either be enhanced or active measures taken. The advantages and disadvantages of various options are discussed: transferring and burying the tailings, perhaps combined with reprocsesing; coating the minerals to prevent oxidation, possibly by CO2 injection; and capping with chemically reactive material that will percolate into the tailings or maintain reducing conditions.

Plant litter of Alnus glutinosa (alder) and Quercus spec. (oak) was investigated in a pond downstream of abandoned uranium mine tailings in Saxony. U concentrations in unwashed samples varied between 20 and 2 000 micrograms/g with around 50 micrograms/g in wood, 200-400 in leaves and 700 in alder cones. Alder leaves contained significantly more U than oak leaves. Washing partially remved attached particles from the leaf surface, reducing concentrations of As and Pb in washed samples, but for U concentrations were greater in washed alder leaves, which contained up to 2 000 micrograms/g, than in unwashed samples., Plant litter of Alnus glutinosa (alder) and Quercus spec. (oak) was investigated in a pond downstream of abandoned uranium mine tailings in Saxony. U concentrations in unwashed samples varied between 20 and 2 000 micrograms/g with around 50 micrograms/g in wood, 200-400 in leaves and 700 in alder cones. Alder leaves contained significantly more U than oak leaves. Washing partially remved attached particles from the leaf surface, reducing concentrations of As and Pb in washed samples, but for U concentrations were greater in washed alder leaves, which contained up to 2 000 micrograms/g, than in unwashed samples.

De-acidification of acid mine waters transfers dissolved U into a colloidal form. Spectroscopic studies of colloid-borne U obtained by simulating mine flooding in the laboratory showed that matrix ions such as sulphate and silicate are not involved in inner-sphere surface sorption complexes of UO2(2+) on ferrihydrite. At ambient air atmosphere, the data suggest the formation of ternary U(VI) carbonato surface complexes with either monodentate or bidentate coordination of carbonate and uranyl, even under moderately acidic conditions. A revised model is proposed for UO2(2+) sorption on ferrihydrite in the absence of carbonate. The next research step will focus on the stabiloity of uranium binding during the transformation of colloids into sediments and crusts, and during the ageing of the metastable ferrihydrite into more crystalline iron minerals., De-acidification of acid mine waters transfers dissolved U into a colloidal form. Spectroscopic studies of colloid-borne U obtained by simulating mine flooding in the laboratory showed that matrix ions such as sulphate and silicate are not involved in inner-sphere surface sorption complexes of UO2(2+) on ferrihydrite. At ambient air atmosphere, the data suggest the formation of ternary U(VI) carbonato surface complexes with either monodentate or bidentate coordination of carbonate and uranyl, even under moderately acidic conditions. A revised model is proposed for UO2(2+) sorption on ferrihydrite in the absence of carbonate. The next research step will focus on the stabiloity of uranium binding during the transformation of colloids into sediments and crusts, and during the ageing of the metastable ferrihydrite into more crystalline iron minerals.

In the present advanced stage of remediation at the Wismut mines in former East Germany, the reutilisation of the reclaimed areas, waste rock piles and tailings ponds is receiving increased attention. Use is normally restricted to industry and trades or forestation, but exemptions are possible if responsibility for long-term monitoring and maintenance is satisfactorily ensured. A mutually beneficial integration of reclamation plans with communal/regional development as been successfully practised in two former mining towns, the first leading to rebirth of the health spa in Schlema and the second to the garden and landscape exhibition hosted by Ronneburg and Gera in 2007., In the present advanced stage of remediation at the Wismut mines in former East Germany, the reutilisation of the reclaimed areas, waste rock piles and tailings ponds is receiving increased attention. Use is normally restricted to industry and trades or forestation, but exemptions are possible if responsibility for long-term monitoring and maintenance is satisfactorily ensured. A mutually beneficial integration of reclamation plans with communal/regional development as been successfully practised in two former mining towns, the first leading to rebirth of the health spa in Schlema and the second to the garden and landscape exhibition hosted by Ronneburg and Gera in 2007.

The main remediation objects in Saxony are waste rock piles, tailings ponds/deposits and underground mines. As their monitoring and maintenance needs differ substantially, regulatory monitoring requirements vary according to an object- or site-specific approach. The qualities of seepage and groundwater are among the most sensitive monitoring parameters; also essential is monitoring the performance and maintenance of covers placed on waste rock piles and tailings to control radon exhalation and contaminated seepage. Remedial measures have been designed for stable performance over a 200-1 000 year period, during which monitoring effort can be decreased if they perform well. Issues discussed include remedial steps, funding, information transfer, institutional control and maintenance., The main remediation objects in Saxony are waste rock piles, tailings ponds/deposits and underground mines. As their monitoring and maintenance needs differ substantially, regulatory monitoring requirements vary according to an object- or site-specific approach. The qualities of seepage and groundwater are among the most sensitive monitoring parameters; also essential is monitoring the performance and maintenance of covers placed on waste rock piles and tailings to control radon exhalation and contaminated seepage. Remedial measures have been designed for stable performance over a 200-1 000 year period, during which monitoring effort can be decreased if they perform well. Issues discussed include remedial steps, funding, information transfer, institutional control and maintenance.

Constructed wetlands are attactive solutions to long-term water treatment at abandoned mining and processing sites, such as those in east Germany where U, Ra and As are the main contaminants and at some sites Ni and other non-radioactive metals are also present. However, scepticism as to the effectiveness and stability of biological water treatment systems is prevalent among practitioners, the public and regulators. Results are presented from a constructed wetland at the Poehla mine site, where a first wetland treated part of the Poehla-Tellerhauser mine-water overflow from 1998 and a pilot-scale wetland subdivided by concrete walls was constructed in a former water-retention basin in 2003. Features included: sedimentation of iron hydroxide flocs; the planting of floating mats, coconut mats and Aqua-mats; gravel and crushed rock for colonisation by microorganisms and for filtration; planting of helophytes to promote the development of biofilms; and a planted bottom filter on compost and gravel. Reactive materials tested for the selective removal of Ra and As from the mine waters were Ferrosorp, a granulated ferric hydroxide, and Hedulat, granulated feldspar in a porous matrix. A full-scale wetland was constructed in 2004, its inclination following that of the Schildbachhalde mine dump., Constructed wetlands are attactive solutions to long-term water treatment at abandoned mining and processing sites, such as those in east Germany where U, Ra and As are the main contaminants and at some sites Ni and other non-radioactive metals are also present. However, scepticism as to the effectiveness and stability of biological water treatment systems is prevalent among practitioners, the public and regulators. Results are presented from a constructed wetland at the Poehla mine site, where a first wetland treated part of the Poehla-Tellerhauser mine-water overflow from 1998 and a pilot-scale wetland subdivided by concrete walls was constructed in a former water-retention basin in 2003. Features included: sedimentation of iron hydroxide flocs; the planting of floating mats, coconut mats and Aqua-mats; gravel and crushed rock for colonisation by microorganisms and for filtration; planting of helophytes to promote the development of biofilms; and a planted bottom filter on compost and gravel. Reactive materials tested for the selective removal of Ra and As from the mine waters were Ferrosorp, a granulated ferric hydroxide, and Hedulat, granulated feldspar in a porous matrix. A full-scale wetland was constructed in 2004, its inclination following that of the Schildbachhalde mine dump.

A water mixing model has been developed to support evaluation of the influence on groundwater aquifers of contaminated water from the flooded Konigstein uranium mine in Germany. The ideas on which the model is based are explained and the model itself described mathematically., A water mixing model has been developed to support evaluation of the influence on groundwater aquifers of contaminated water from the flooded Konigstein uranium mine in Germany. The ideas on which the model is based are explained and the model itself described mathematically.

Column experiments used synthetic rock-pile seepage water, based on samples from Schlema uranium mine in Germany, percolating through packed quartz sand to quantify and characterise U(VI) retardation by hydroxyapatite. Batch experiments were also of assistance in assessing hydroxyapatite as a potential component for reactive barriers. The sorption of uranyl ions on phophate groups was found to be as important as their sorption on silanol groups, outweighing the low phosphate content. In the column experiments, retardation factors of around 30 were observed. The results suggested that the elution of U is governed by two processes of different rate, a conclusion consistent with the findings of time-resolved laser-induced fluorescence spectroscopy., Column experiments used synthetic rock-pile seepage water, based on samples from Schlema uranium mine in Germany, percolating through packed quartz sand to quantify and characterise U(VI) retardation by hydroxyapatite. Batch experiments were also of assistance in assessing hydroxyapatite as a potential component for reactive barriers. The sorption of uranyl ions on phophate groups was found to be as important as their sorption on silanol groups, outweighing the low phosphate content. In the column experiments, retardation factors of around 30 were observed. The results suggested that the elution of U is governed by two processes of different rate, a conclusion consistent with the findings of time-resolved laser-induced fluorescence spectroscopy.

Results from the Wismut region of Germany are used to examine hydrodynamic aspects of contaminant transport from uranium mine tailings deposits via alluvial groundwater into a receiving stream. Event-related hydraulic interactions between groundwater and surface water in the hyporheic zone were observed by means of long-term, quasi-continuous in- situ measurements with electronic probes. Time-series analysis suggests that interactions between contaminated groundwater, porewater in channel sediments and stream water are highly dynamic, impacting on U fluxes and mobility. Processes observed during flood events also question established views on run-off generation in streams., Results from the Wismut region of Germany are used to examine hydrodynamic aspects of contaminant transport from uranium mine tailings deposits via alluvial groundwater into a receiving stream. Event-related hydraulic interactions between groundwater and surface water in the hyporheic zone were observed by means of long-term, quasi-continuous in- situ measurements with electronic probes. Time-series analysis suggests that interactions between contaminated groundwater, porewater in channel sediments and stream water are highly dynamic, impacting on U fluxes and mobility. Processes observed during flood events also question established views on run-off generation in streams.

In uranium mining areas, it is hard to determine whether increases in U, Ra or Rn levels are the result of mining or of natural variation, as there are rarely reliable pre-mining data. A study was therefore undertaken in the Swiss Alps, a region with known but unmined low-grade U mineralisation, to investigate the range of spatial and temporal variations in the natural background. These may also serve as a baseline for measuring possible future influences of climate change or industrial activity in the area. Large spatial and temporal variations in U-series concentrations were observed in groundwater, both from pumped drinking water and from mineral water springs; a total of 400 different springs and groundwaters were sampled in the canton of Grisons and 50 in Valais, with time series of months to years taken by sampling 5 springs and 5 public fountains in Valais at monthly intervals. Observed trends that provide the first steps towards a conceptual model included Rn concentrations above 50 Mq/l being a very localised phenomenon, connected with Ra adsorption on iron hydroxides where young O2-rich waters mix with old anoxic waters, 226Ra concentrations being increased up to 200 mBq/l in anoxic waters from limestone formations, especially at higher temperatures, and 238U concentrations being increased to more than 100 mBq/l in cold, O2-rich waters with low mineralisation from crystalline rocks, where at least some of the U is present as UO2(2+), or in cold, highly mineralised sulphate-rich waters where U is complexed with CO2., In uranium mining areas, it is hard to determine whether increases in U, Ra or Rn levels are the result of mining or of natural variation, as there are rarely reliable pre-mining data. A study was therefore undertaken in the Swiss Alps, a region with known but unmined low-grade U mineralisation, to investigate the range of spatial and temporal variations in the natural background. These may also serve as a baseline for measuring possible future influences of climate change or industrial activity in the area. Large spatial and temporal variations in U-series concentrations were observed in groundwater, both from pumped drinking water and from mineral water springs; a total of 400 different springs and groundwaters were sampled in the canton of Grisons and 50 in Valais, with time series of months to years taken by sampling 5 springs and 5 public fountains in Valais at monthly intervals. Observed trends that provide the first steps towards a conceptual model included Rn concentrations above 50 Mq/l being a very localised phenomenon, connected with Ra adsorption on iron hydroxides where young O2-rich waters mix with old anoxic waters, 226Ra concentrations being increased up to 200 mBq/l in anoxic waters from limestone formations, especially at higher temperatures, and 238U concentrations being increased to more than 100 mBq/l in cold, O2-rich waters with low mineralisation from crystalline rocks, where at least some of the U is present as UO2(2+), or in cold, highly mineralised sulphate-rich waters where U is complexed with CO2.

In the uranium mining area of former East Germany, small natural wetlands were studied to determine their efficiency in removing uranium. Surface water samples, plant material, sediment cores and pore waters were investigated to understand the hydrogeochemical processes assumed to be responsible for uranium accumulation in the wetlands. It was found that the U contents of the wetland substrates are up to 3 000 times greater than pore-water values. Autoradiography and SEM/EDX studies revealed that U is evenly dispersed in the wetland soils, where it appears to be adsorbed mainly to organic matter, as shown by sequential extractions. There was no evidence for precipitation of uranium minerals., In the uranium mining area of former East Germany, small natural wetlands were studied to determine their efficiency in removing uranium. Surface water samples, plant material, sediment cores and pore waters were investigated to understand the hydrogeochemical processes assumed to be responsible for uranium accumulation in the wetlands. It was found that the U contents of the wetland substrates are up to 3 000 times greater than pore-water values. Autoradiography and SEM/EDX studies revealed that U is evenly dispersed in the wetland soils, where it appears to be adsorbed mainly to organic matter, as shown by sequential extractions. There was no evidence for precipitation of uranium minerals.

A methodology is suggested for life-cycle assessment of environmental protection measures and remedial actions, using the reclamation of mine sites as an example. Factors to be included in site assessment and option evaluation include human carcinogens, toxins and radiological hazards, environmental detriments such as damage to ecosystems, damage to water resources, and direct physical risks such as dam failures or risks from clean-up activities., A methodology is suggested for life-cycle assessment of environmental protection measures and remedial actions, using the reclamation of mine sites as an example. Factors to be included in site assessment and option evaluation include human carcinogens, toxins and radiological hazards, environmental detriments such as damage to ecosystems, damage to water resources, and direct physical risks such as dam failures or risks from clean-up activities.

Remediation and monitoring, in particular assisted by the commissioning of modern water treatment plants, have reduced uranium discharges from Wismut's former East German mines in Thuringia and Saxony from a total of 27.5 tonnes in 1989 to less than 3 t in 2004. Resulting site-specific doses to the population are significantly below 1 mSv/a. However, diffuse discharges of contaminated seepage or percolation waters from tailings ponds may cause doses in the order of 1 mSv/a. Capping operations are instrumental in reducing such discharge of radioactive effluent via the water pathway to a reasonably low level., Remediation and monitoring, in particular assisted by the commissioning of modern water treatment plants, have reduced uranium discharges from Wismut's former East German mines in Thuringia and Saxony from a total of 27.5 tonnes in 1989 to less than 3 t in 2004. Resulting site-specific doses to the population are significantly below 1 mSv/a. However, diffuse discharges of contaminated seepage or percolation waters from tailings ponds may cause doses in the order of 1 mSv/a. Capping operations are instrumental in reducing such discharge of radioactive effluent via the water pathway to a reasonably low level.

A new biosorbent called Biocer was developed to combine the excellent adsorption capacity of Bacillus sphaericus for U and other heavy metals with mechanical stability, by means of sol-gel technology. The biological cells are firmly bound in the ceramic material, whereas harmful metal ions can diffuse through the pores of the ceramics to become adsorbed on the cell walls. The biosorption of Cu, Zn and As on the original Biocer material was investigated and different carrier materials were then compared, including Al2O3 and a geopolymer, to improve the long-term mechanical and hydrolytic stability of the biosorbents. Preliminary column experiments with real mine drainage waters resulted in good removal of U and other heavy metals., A new biosorbent called Biocer was developed to combine the excellent adsorption capacity of Bacillus sphaericus for U and other heavy metals with mechanical stability, by means of sol-gel technology. The biological cells are firmly bound in the ceramic material, whereas harmful metal ions can diffuse through the pores of the ceramics to become adsorbed on the cell walls. The biosorption of Cu, Zn and As on the original Biocer material was investigated and different carrier materials were then compared, including Al2O3 and a geopolymer, to improve the long-term mechanical and hydrolytic stability of the biosorbents. Preliminary column experiments with real mine drainage waters resulted in good removal of U and other heavy metals.

The regulatory regimes for underground, open-cut and in-situ leach uranium operations in the wet-dry tropical to arid desert zones of the Northern Territory and South Australia involve a complex mix of federal and state governments as well as traditional Aboriginal Landowners and other significant stakeholders. These different agencies and organisations work together to ensure that the mines are operated in accordance with the expectations of the community in terms of their environment, health and safety while still maintaining economic viability and operational efficiency. Following the environmental enquiry into the proposed development of the Ranger uranium mine in the Northern Territory, the open-cut mine was developed although the underground Jabiluka project was subsequently terminated. In South Australia, the two established operations are the Olympic Dam underground mine and in-situ leaching at Beverley. The seven most significant Acts by which the Australian government regulates uranium mining are listed as well as the three Codes of Practice dealing with radiation protection. Legislation and regulation in each of the two uranium-mining states are discussed as well as environmental management and monitoring in the environs of the Northern Territory's Kakadu national park, with its wetlands and floodplains., The regulatory regimes for underground, open-cut and in-situ leach uranium operations in the wet-dry tropical to arid desert zones of the Northern Territory and South Australia involve a complex mix of federal and state governments as well as traditional Aboriginal Landowners and other significant stakeholders. These different agencies and organisations work together to ensure that the mines are operated in accordance with the expectations of the community in terms of their environment, health and safety while still maintaining economic viability and operational efficiency. Following the environmental enquiry into the proposed development of the Ranger uranium mine in the Northern Territory, the open-cut mine was developed although the underground Jabiluka project was subsequently terminated. In South Australia, the two established operations are the Olympic Dam underground mine and in-situ leaching at Beverley. The seven most significant Acts by which the Australian government regulates uranium mining are listed as well as the three Codes of Practice dealing with radiation protection. Legislation and regulation in each of the two uranium-mining states are discussed as well as environmental management and monitoring in the environs of the Northern Territory's Kakadu national park, with its wetlands and floodplains.

Inadequate remediation of trial mining at Ryst Kuil and Rietkuil left a disused open pit and inclined shaft, uranium ore in rows of stockpiles and barrels, as well as mining-related equipment. Landowners, unaware of the potential threat of uranium and heavy metals, grazed livestock among the stockpiles, allowed them to drink from contaminated water supplies, irrigated crops with water from the shaft, and used stockpiled ore to maintain gravel roads and construct housing foundations, leading to the accumulations of radon gas in the homestead up to 835 Bq/m3, exceeding the US Environmental Protection Agency's limit of 150 Bq/m3. The leaves and roots of Lycium cinereum, Fingerhuthia africana, Aristida congesta and Phragmites australis growing with the mining locations had high concentrations of U and Mo, while protein studies showed a general tendency for the increase in U and Mo to be accompanied by decreased protein concentrations in the leaves. Aquatic organisms in a water-filled open pit with 20 mg/l U and 4 mg/l Mo had high hepatic, renal and bone concentrations of both metals and anomalous levels of lymphocytes, indicative of infections., Inadequate remediation of trial mining at Ryst Kuil and Rietkuil left a disused open pit and inclined shaft, uranium ore in rows of stockpiles and barrels, as well as mining-related equipment. Landowners, unaware of the potential threat of uranium and heavy metals, grazed livestock among the stockpiles, allowed them to drink from contaminated water supplies, irrigated crops with water from the shaft, and used stockpiled ore to maintain gravel roads and construct housing foundations, leading to the accumulations of radon gas in the homestead up to 835 Bq/m3, exceeding the US Environmental Protection Agency's limit of 150 Bq/m3. The leaves and roots of Lycium cinereum, Fingerhuthia africana, Aristida congesta and Phragmites australis growing with the mining locations had high concentrations of U and Mo, while protein studies showed a general tendency for the increase in U and Mo to be accompanied by decreased protein concentrations in the leaves. Aquatic organisms in a water-filled open pit with 20 mg/l U and 4 mg/l Mo had high hepatic, renal and bone concentrations of both metals and anomalous levels of lymphocytes, indicative of infections.

Following remediation at the Schlema-Alberoda site in Saxony, east Germany, the existing water monitoring regime has had to be reduced and modified to focus on the main contaminated streams. The basic concept used for objective assessment of waste water within the EU and in the European Water Framework Directive is that of critical loads, rather than critical levels or concentrations, of radioactive or toxic compounds. Contaminated and uncontaminated surface and underground flows have to be distinguished and their transported loads determined. Results are presented for arsenic and uranium loads in active and abandoned mines from 1995 to 2004., Following remediation at the Schlema-Alberoda site in Saxony, east Germany, the existing water monitoring regime has had to be reduced and modified to focus on the main contaminated streams. The basic concept used for objective assessment of waste water within the EU and in the European Water Framework Directive is that of critical loads, rather than critical levels or concentrations, of radioactive or toxic compounds. Contaminated and uncontaminated surface and underground flows have to be distinguished and their transported loads determined. Results are presented for arsenic and uranium loads in active and abandoned mines from 1995 to 2004.

In large parts of the Witwatersrand basin, gold mining has developed beneath extensive, compartmentalised karst aquifers in dolomitic bedrock, hosting large volumes of groundwater. The past, present and future significance of estimated potential U fluxes associated with different types of mining sources is assessed for the area between the uranium-rich gold reefs of the old West Rand mining area and the more recently developed Far West Rand. Possible non-mine sources of contamination include impacts from the production and application of uraniferous phosphate fertiliser, air- and water-borne or road transport from the U refinery, or contact of free-moving water with natural orebodies; mining- related sources can be divided into on-site and off-site or into point and diffuse sources, the former comprising in particular mining effluents, domestic waste water from mining-related sewage plants and polluted run- off from storm drains, while the latter include seepage from slimes dams and sinkholes filled with tailings material., In large parts of the Witwatersrand basin, gold mining has developed beneath extensive, compartmentalised karst aquifers in dolomitic bedrock, hosting large volumes of groundwater. The past, present and future significance of estimated potential U fluxes associated with different types of mining sources is assessed for the area between the uranium-rich gold reefs of the old West Rand mining area and the more recently developed Far West Rand. Possible non-mine sources of contamination include impacts from the production and application of uraniferous phosphate fertiliser, air- and water-borne or road transport from the U refinery, or contact of free-moving water with natural orebodies; mining- related sources can be divided into on-site and off-site or into point and diffuse sources, the former comprising in particular mining effluents, domestic waste water from mining-related sewage plants and polluted run- off from storm drains, while the latter include seepage from slimes dams and sinkholes filled with tailings material.

A combined remediation strategy at the German mine site since 1991 has consisted of the following central elements: cleaning up operational areas, backfilling the open pit with waste rock from the surrounding areas, flooding the underground mine and constructing and operating technical water management systems. Environmental benefits included an end to water-quality problems caused by the widespread spoil heaps, immobilisation of toxic substances around the open pit and underground mine, and the termination of effluent discharge from the mine drainage system into surface water-courses, whose pollution levels have greatly improved as a result. These effects allowed additional contruction and operating costs of water treatment systems to be kept to a minimum., A combined remediation strategy at the German mine site since 1991 has consisted of the following central elements: cleaning up operational areas, backfilling the open pit with waste rock from the surrounding areas, flooding the underground mine and constructing and operating technical water management systems. Environmental benefits included an end to water-quality problems caused by the widespread spoil heaps, immobilisation of toxic substances around the open pit and underground mine, and the termination of effluent discharge from the mine drainage system into surface water-courses, whose pollution levels have greatly improved as a result. These effects allowed additional contruction and operating costs of water treatment systems to be kept to a minimum.

A detailed study, undertaken to evaluate various cover systems and final landform designs for decommissioning a waste area at the Saskatchewan uranium mine, included physical and hydraulic characterisation of waste and cover materials, numerical modelling of erosion and slope stability, soil-atmosphere numerical simulations to predict net infiltration and oxygen ingress rates, and a modelling programme for seepage from the base of the pile. Several final landform alternatives were developed for the pile of waste rock, along with a preliminary design for a system of surface water management. The potential impacts of various physical, chemical and biological processes on the sustainable performance of the final landform were also considered. The selected cover consists of 0.2 m of compacted in-situ waste rock overlain by 1.0 m of non-compacted sandy till, and the preferred final landform has two 4.4 ha catchments that channel runoff to a lightly armoured central drainage channel and thence to heavily armoured slope channels; the north and south slopes are linear with 75 mm median stone size while the east and west slopes are concave from 50% in the upper quarter to 20% for the lower three-quarters., A detailed study, undertaken to evaluate various cover systems and final landform designs for decommissioning a waste area at the Saskatchewan uranium mine, included physical and hydraulic characterisation of waste and cover materials, numerical modelling of erosion and slope stability, soil-atmosphere numerical simulations to predict net infiltration and oxygen ingress rates, and a modelling programme for seepage from the base of the pile. Several final landform alternatives were developed for the pile of waste rock, along with a preliminary design for a system of surface water management. The potential impacts of various physical, chemical and biological processes on the sustainable performance of the final landform were also considered. The selected cover consists of 0.2 m of compacted in-situ waste rock overlain by 1.0 m of non-compacted sandy till, and the preferred final landform has two 4.4 ha catchments that channel runoff to a lightly armoured central drainage channel and thence to heavily armoured slope channels; the north and south slopes are linear with 75 mm median stone size while the east and west slopes are concave from 50% in the upper quarter to 20% for the lower three-quarters.

In order to reduce contaminant potential during flooding of the former in-situ leaching mine at Konigstein in Germany, a new technology was based on the injection of supersaturated barium sulphate solutions to precipitate dissolved contaminants and to cover reactive mineral surfaces. The technique was applied from 2002 in the southern part of the mine to immobilise contaminants in highly polluted areas before flooding., In order to reduce contaminant potential during flooding of the former in-situ leaching mine at Konigstein in Germany, a new technology was based on the injection of supersaturated barium sulphate solutions to precipitate dissolved contaminants and to cover reactive mineral surfaces. The technique was applied from 2002 in the southern part of the mine to immobilise contaminants in highly polluted areas before flooding.

During its years of operation, the Moab processing facility accumulated around 10 500 000 t tailngs and contaminated soils in an unlined pile about 230 m from the Colorado River. The alternatives preferred by the US Department of Energy are to relocate the tailings on an alternative site away from the river and to remediate the groundwater in the long term; in the interim, a groundwater extraction and injection system is in operation to reduce the contaminant mass in groundwater discharging to the river. A conceptual hydrogeological model is presented, the nature of the groundwater contamination discussed, dewatering of the tailings fluid outlined and the extraction and freshwater injection described, including treatment of the exrtacted water in a solar evaporation pond., During its years of operation, the Moab processing facility accumulated around 10 500 000 t tailngs and contaminated soils in an unlined pile about 230 m from the Colorado River. The alternatives preferred by the US Department of Energy are to relocate the tailings on an alternative site away from the river and to remediate the groundwater in the long term; in the interim, a groundwater extraction and injection system is in operation to reduce the contaminant mass in groundwater discharging to the river. A conceptual hydrogeological model is presented, the nature of the groundwater contamination discussed, dewatering of the tailings fluid outlined and the extraction and freshwater injection described, including treatment of the exrtacted water in a solar evaporation pond.

At the Avram Iancu uranium mine in Romania, significant amounts of radioactive waste rock have accumulated and pose a major threat to the environment. Analysis of the particular conditions of the mine surroundings led to the conclusion that relocation of the contaminated material in the abandoned mine galleries would provide the most cost- effective long-term protection against radiation. After selection by radiological measurement, waste rock was transported from the heaps to the mine adits with a front-end loader and trucks for stowing in the cross-cuts at a volume of about 3 m3 per metre of gallery. The waste rock was reshaped and the adits closed off with dykes. Potential disturbances and risks considered included subsidence phenomena, topographic modifications, changes in hydrology and landslides; the selected locations were outside the influence of mining activity and were not in the vicinity of deep faults, with no major infiltration anticipated and the horizontal mine workings in good condition., At the Avram Iancu uranium mine in Romania, significant amounts of radioactive waste rock have accumulated and pose a major threat to the environment. Analysis of the particular conditions of the mine surroundings led to the conclusion that relocation of the contaminated material in the abandoned mine galleries would provide the most cost- effective long-term protection against radiation. After selection by radiological measurement, waste rock was transported from the heaps to the mine adits with a front-end loader and trucks for stowing in the cross-cuts at a volume of about 3 m3 per metre of gallery. The waste rock was reshaped and the adits closed off with dykes. Potential disturbances and risks considered included subsidence phenomena, topographic modifications, changes in hydrology and landslides; the selected locations were outside the influence of mining activity and were not in the vicinity of deep faults, with no major infiltration anticipated and the horizontal mine workings in good condition.

Batch experiments in glass test tubes with natural iron materials and scrap iron suggested the prevalent role of the scrap iron's corrosion products in immobilising U but also those of potassium in KCl background electrolyte and of calcite. Effluent samples from columns packed with 90% sand and 10% scrap Fe showed fixation of more than 95% of both U and As from Schneckenstein German tailings leachate upgraded to 0.05 mM U and As (11.9 mg/l U, 3.7 mg/l As), but a control column leached only with the 0. 01 M KCl background electrolyte unexpectedly also fixed 90-95% of both U and As. This result indicates possible precipitation or coi-precipitation through sparingly soluble minerals such as abernathyite, KUO2AsO4.4H2O, as predicted by PHREEQC code modelling. Thus K may be an efficient and cost-effective amendment for immobilising high concentrations of U and As in contaminated porous media, though the reduction of both is limited by the solubility product of abernathyite maintaining U and As concentrations in the range of tens of micrograms per litre. As an essential intercellular nutrient, K might play a double role by also enhancing bacterially mediated biotransformation and immobilisation of U and As., Batch experiments in glass test tubes with natural iron materials and scrap iron suggested the prevalent role of the scrap iron's corrosion products in immobilising U but also those of potassium in KCl background electrolyte and of calcite. Effluent samples from columns packed with 90% sand and 10% scrap Fe showed fixation of more than 95% of both U and As from Schneckenstein German tailings leachate upgraded to 0.05 mM U and As (11.9 mg/l U, 3.7 mg/l As), but a control column leached only with the 0. 01 M KCl background electrolyte unexpectedly also fixed 90-95% of both U and As. This result indicates possible precipitation or coi-precipitation through sparingly soluble minerals such as abernathyite, KUO2AsO4.4H2O, as predicted by PHREEQC code modelling. Thus K may be an efficient and cost-effective amendment for immobilising high concentrations of U and As in contaminated porous media, though the reduction of both is limited by the solubility product of abernathyite maintaining U and As concentrations in the range of tens of micrograms per litre. As an essential intercellular nutrient, K might play a double role by also enhancing bacterially mediated biotransformation and immobilisation of U and As.

Uranium mill tailings contain large amounts of radium as well as other radionuclides such as U, Th, Po and Pb. Their transport and fate in groundwater are assumed to follow the theoretical approach represented by a basic diffusion/dispersion-advection equation. An algorithm is presented that uses the analytical solution for one-dimensional steady- state transport of a reactive subsctance with simultaneous retardation and radioactive decay. The final output is the radionuclide concentration in a hypothetical well location as a function of elapsed time. Results are given from application of the model to a cases study of the Urgeirica tailings-contaminated site in Portugal, where radium was mined from 1913 and uranium concentrates treated from 1951 until 2000, mining having ceased in 1991 leaving around 4 000 000 t of spoil in addition to the sand/silt tailings. The model was tested in different situations with varying parameters derived or estimated from published data, to determine when and in what concentrations radionuclides might be transported to the aquifer and reach local wells., Uranium mill tailings contain large amounts of radium as well as other radionuclides such as U, Th, Po and Pb. Their transport and fate in groundwater are assumed to follow the theoretical approach represented by a basic diffusion/dispersion-advection equation. An algorithm is presented that uses the analytical solution for one-dimensional steady- state transport of a reactive subsctance with simultaneous retardation and radioactive decay. The final output is the radionuclide concentration in a hypothetical well location as a function of elapsed time. Results are given from application of the model to a cases study of the Urgeirica tailings-contaminated site in Portugal, where radium was mined from 1913 and uranium concentrates treated from 1951 until 2000, mining having ceased in 1991 leaving around 4 000 000 t of spoil in addition to the sand/silt tailings. The model was tested in different situations with varying parameters derived or estimated from published data, to determine when and in what concentrations radionuclides might be transported to the aquifer and reach local wells.

The results of nine multi-tracer tests of nearly 30 different flow paths conducted by the Bergakademie Freiberg are briefly re-examined and conclusions drawn from two interesting overall results. The tests used 2- 6 injection points and up to 3 different tracer types, chosen from Lycopodium spores, microspheres, Na-fluorescein and rock-salt brine. In all but one case it was found that the simple analytical piston flow model used to determine the amount of tracer needed and possible duration of the test from preliminary flow measurements completely underestimated flow velocities and over-estimated test duration by factors of 2-5. No general rule for finding a reliable correction factor could be deduced from the results. The high wall roughness in adits and galleries might have been expected to result in lower effective velocities than those calculated. A further finite-element model was set up and calibrated for the tracer results from Brixlegg in Tyrol, but the reasons for the discrepancy between the two models remained unclear. The second general result was more easily understood: the longer water flows through horizontal mine workings, which are much narrower than shafts, the greater the effective velocity; also, complicated mine geometries with many shafts and levels have higher effective velocities than simpler geometries, to the extent that a tracer in the underground Rabenstein limestone mine in Saxony, with only two shafts and two levels, needed nearly two years to return to background values whereas the complex Niederschlema-Alberoda mine had extremely quick response times over distances of nearly 3 km. It is recommended that upper and lower levels of mines be separated and that the flushing through of pollutants be controlled by damming horizontal workings to minimise annual loads or vertical workings to achieve an early peak concentration., The results of nine multi-tracer tests of nearly 30 different flow paths conducted by the Bergakademie Freiberg are briefly re-examined and conclusions drawn from two interesting overall results. The tests used 2- 6 injection points and up to 3 different tracer types, chosen from Lycopodium spores, microspheres, Na-fluorescein and rock-salt brine. In all but one case it was found that the simple analytical piston flow model used to determine the amount of tracer needed and possible duration of the test from preliminary flow measurements completely underestimated flow velocities and over-estimated test duration by factors of 2-5. No general rule for finding a reliable correction factor could be deduced from the results. The high wall roughness in adits and galleries might have been expected to result in lower effective velocities than those calculated. A further finite-element model was set up and calibrated for the tracer results from Brixlegg in Tyrol, but the reasons for the discrepancy between the two models remained unclear. The second general result was more easily understood: the longer water flows through horizontal mine workings, which are much narrower than shafts, the greater the effective velocity; also, complicated mine geometries with many shafts and levels have higher effective velocities than simpler geometries, to the extent that a tracer in the underground Rabenstein limestone mine in Saxony, with only two shafts and two levels, needed nearly two years to return to background values whereas the complex Niederschlema-Alberoda mine had extremely quick response times over distances of nearly 3 km. It is recommended that upper and lower levels of mines be separated and that the flushing through of pollutants be controlled by damming horizontal workings to minimise annual loads or vertical workings to achieve an early peak concentration.

An investigation of the area around the former Ilisova uranium mines and pilot in-situ leaching plant, located 50 m from the Danube in a SW Romanian national park, included field measurement of gamma radiation, rock sampling and analysis for U, Ra, Cu, Pb, Zn, Ni and Co, water sampling, determination of radon levels and the collecting of water, soil, sediment and vegetation samples from around the pilot plant. Cumulative doses were calculated on the basis of 5 months' exposure each year for 6 hours/day, as the houses in the area are for summer use only. The results showed that the plant activities had contaminated about 7 000 m2 of the surface as well as part of the groundwater of the former ore deposit. The highest risk to the population is from the concrete tank, which still contains amounts of ore, and the surface of the former ore deposit, which could at any time be used for picnicing by visitors to the national park., An investigation of the area around the former Ilisova uranium mines and pilot in-situ leaching plant, located 50 m from the Danube in a SW Romanian national park, included field measurement of gamma radiation, rock sampling and analysis for U, Ra, Cu, Pb, Zn, Ni and Co, water sampling, determination of radon levels and the collecting of water, soil, sediment and vegetation samples from around the pilot plant. Cumulative doses were calculated on the basis of 5 months' exposure each year for 6 hours/day, as the houses in the area are for summer use only. The results showed that the plant activities had contaminated about 7 000 m2 of the surface as well as part of the groundwater of the former ore deposit. The highest risk to the population is from the concrete tank, which still contains amounts of ore, and the surface of the former ore deposit, which could at any time be used for picnicing by visitors to the national park.

The U content of Witwatersrand ores and the great age of these South African deposits have led to the development of highly radiogenic Pb isotope ratios which are reflected in mine-generated wastes and effluents, so that the sources of contamination may be identified and traced back to the Witwatersrand. Where fine sediments act as accumulators of heavy metals in the streams and rivers downstream of mining activities, analysis of their Pb isotopic compositions can be used to identify and apportion sources of contamination. In a study of the Wonderfonteinspruit catchment, samples were collected of mine tailings that represented orebodies mined in the West Rand and Far West Rand goldfields drained by the river. River sediments downstream of the relevant mines were sampled and uncontaminated sediments used to provide background compositions. The isotopic composition of South African leaded petrol was also included. The two distinct trends identified on a graph of the results represented mixing lines from the mine source to the upper catchment and from the background source to the lower river catchment, showing that there is little downstream transport of Pb., The U content of Witwatersrand ores and the great age of these South African deposits have led to the development of highly radiogenic Pb isotope ratios which are reflected in mine-generated wastes and effluents, so that the sources of contamination may be identified and traced back to the Witwatersrand. Where fine sediments act as accumulators of heavy metals in the streams and rivers downstream of mining activities, analysis of their Pb isotopic compositions can be used to identify and apportion sources of contamination. In a study of the Wonderfonteinspruit catchment, samples were collected of mine tailings that represented orebodies mined in the West Rand and Far West Rand goldfields drained by the river. River sediments downstream of the relevant mines were sampled and uncontaminated sediments used to provide background compositions. The isotopic composition of South African leaded petrol was also included. The two distinct trends identified on a graph of the results represented mixing lines from the mine source to the upper catchment and from the background source to the lower river catchment, showing that there is little downstream transport of Pb.

Canada's Nuclear Safety and Control Act 2000 brought new attention to the assessment and regulation of legacy properties, mostly abandoned with their safety and long-term management the responsibility of various levels of government. The idle mine portion of the Contaminated Lands Evaluation and Assessment Network (CLEAN) programme began an outreach programme to inform various stakeholders of their responsibilties under the Act and to catalogue the available information for each of the mines. This resulted in two separate initiatives, one to license high-risk sites and one to exempt radiologically low-risk sites from Canadian Nuclear Safety Commission licensing. The mandates of other regulatory agencies were taken into account by granting exemptions to allow processes such as the assessment of the Port Radium mine in the Northwest Territories, by Indian and Northern Affairs Canada in conjunction with the native community at Deline, or the implementation of an institutional control policy for the long-term management of idle mine sites at Gunnar in Saskatchewan, by the provincial government. A risk assessment of 75 mine- only sites without tailings, backed up by field testing at around 20 of the highest-risk sites, eventually determined that none of the mines without tailings presented a radiological hazard and that all could be exempt from the licensing requirements and left to the provinces to regulate for conventional and environmental hazards. Through patience and flexibility, the CLEAN programme has licensed 16 of the 19 idle mines with tailings across Canada and immediate safety precautions have been undertaken at the 3 sites still at various stages of licensing., Canada's Nuclear Safety and Control Act 2000 brought new attention to the assessment and regulation of legacy properties, mostly abandoned with their safety and long-term management the responsibility of various levels of government. The idle mine portion of the Contaminated Lands Evaluation and Assessment Network (CLEAN) programme began an outreach programme to inform various stakeholders of their responsibilties under the Act and to catalogue the available information for each of the mines. This resulted in two separate initiatives, one to license high-risk sites and one to exempt radiologically low-risk sites from Canadian Nuclear Safety Commission licensing. The mandates of other regulatory agencies were taken into account by granting exemptions to allow processes such as the assessment of the Port Radium mine in the Northwest Territories, by Indian and Northern Affairs Canada in conjunction with the native community at Deline, or the implementation of an institutional control policy for the long-term management of idle mine sites at Gunnar in Saskatchewan, by the provincial government. A risk assessment of 75 mine- only sites without tailings, backed up by field testing at around 20 of the highest-risk sites, eventually determined that none of the mines without tailings presented a radiological hazard and that all could be exempt from the licensing requirements and left to the provinces to regulate for conventional and environmental hazards. Through patience and flexibility, the CLEAN programme has licensed 16 of the 19 idle mines with tailings across Canada and immediate safety precautions have been undertaken at the 3 sites still at various stages of licensing.

Exploitation of uranium ore at Barzava, in westerrn Romania, began in 1963 via two shafts and two galleries. Waste rock from the central shaft is located in Barzava city, extremely close to the river and occupying a surface area of 3 600 m3, where forty years of erosion-related U and Ra migration from spoil has contaminated soil at the base of the dump. Results are presented from the sampling of vegetation, particularly in the direction of flow, and from calculations of potential internal and external radiation dosages to adults through internal ingestion in water or food, ingestion into the airways, or external irradiation., Exploitation of uranium ore at Barzava, in westerrn Romania, began in 1963 via two shafts and two galleries. Waste rock from the central shaft is located in Barzava city, extremely close to the river and occupying a surface area of 3 600 m3, where forty years of erosion-related U and Ra migration from spoil has contaminated soil at the base of the dump. Results are presented from the sampling of vegetation, particularly in the direction of flow, and from calculations of potential internal and external radiation dosages to adults through internal ingestion in water or food, ingestion into the airways, or external irradiation.

Low-grade uranium ore was first mined at Jaduguda in the mid-1960s and Uranium Corporation of India now processes ore from four underground mines within 22 km, a few more mines being envisaged to meet requirements for nuclear fuel. Due emphasis is placed on the management of mine water, mill tailings and effluent from the tailings containment facility. Liquid effluents are treated with BaCl2 and lime slurry to remove 226Ra, Mn and other pollutants. A large proportion of the treated effluent is reused, the rest being discharged to the aquatic system after meeting regulatory standards. Surface and groundwater monitoring results are presented., Low-grade uranium ore was first mined at Jaduguda in the mid-1960s and Uranium Corporation of India now processes ore from four underground mines within 22 km, a few more mines being envisaged to meet requirements for nuclear fuel. Due emphasis is placed on the management of mine water, mill tailings and effluent from the tailings containment facility. Liquid effluents are treated with BaCl2 and lime slurry to remove 226Ra, Mn and other pollutants. A large proportion of the treated effluent is reused, the rest being discharged to the aquatic system after meeting regulatory standards. Surface and groundwater monitoring results are presented.