AUSTRALIA'S URANIUM MINES

AUSTRALIA'S URANIUM MINES

PAST AND PRESENT

Paul Kay

Science, Technology, Environment and Resource Group,

Parliamentary Library

MAJOR ISSUES

The Ranger mine in the Northern Territory is probably the most closely supervised mining and milling establishment in Australia. The government funded Office of the Supervising Scientist monitors the mines operations, and carries out research studies into the impact of mining. The Supervising Scientist has noted several water spills or leaks since the commencement of mining in 1980, but states that “no significant effects upon the environment were recorded”.

Development planned at Ranger relies on the use of the existing mine pit, from Number 1 Orebody as the future tailings impoundment. Tailings from Jabiluka, if developed would also be stored in the old Number 1 Orebody pit. However, the key difference between tailings disposal in a tailings dam and an old mine is access to the water table. Engineering solutions to prevent egress of water to and from the old Number 1 orebody will need to be employed. In any case, risks to groundwater are increased relative to `dry' impoundments above ground.

Uranium mining and milling operations in Australia have a chequered history in terms of environmental management. The operating mines, Ranger and Olympic Dam, demonstrate how mining operations can function with limited impact on the environment. Older mines however, were developed with little consideration of the environment in remote areas with little or no public scrutiny. Rehabilitation of these older mines immediately following mine closure was minimal, leaving problems such as acid mine drainage. Comparing these problems with mines planned and operated under contemporary legislation and public scrutiny is not appropriate as circumstances are entirely different. New mines developed in Australia would have more in common with Ranger or Olympic Dam than they would with Rum Jungle or Radium Hill.

While the operating mines do conform to high standards of environmental management, this has not meant that they are immune to public criticism. Ranger has a long history of water release issues recorded in the media and Olympic Dam has also experienced some exposure. The reaction of some groups in the community to any development uranium or nuclear technology may go some way to explaining this exposure, but it does not mean that the issues are not relevant.

HISTORIC URANIUM MINES

Radium Hill, South Australia, 1954-62

Radium Hill in eastern South Australia, was initially operated as an underground mine in the 1930s for minute amounts of radium for medical purposes. A few hundred kilograms of uranium ore were produced as a by product and used a bright yellow pigment in glass and ceramics. The South Australian government recommissioned the underground mine in 1954 to supply uranium oxide (U3O8) to the UK-USA Combined Development Agency (CDA) for seven years. Ore concentration by heavy media separation was carried out at Radium Hill. The concentrate was railed 300 kilometres to a treatment at Port Pirie to produce 160 tonnes of uranium oxide per annum. The mine operated from 1954 to 1961, the treatment plant from 1956 to February 1962 and a total of 850 tonnes of uranium oxide.

Rum Jungle, Northern Territory, 1954-71

The Rum Jungle deposit was discovered in 1949 and is located 64 kilometres south of Darwin on the East Finniss River. The Commonwealth Government provided funds for setting up a mine and treatment plant in March 1952. A contract with the UK-USA CDA ran from 1953 to 1962 to provide uranium oxide concentrate from Rum Jungle. The Commonwealth, through the Australian Atomic Energy Commission (AAEC), was responsible for the mine. Contracted management of the mine was by a subsidiary of Consolidated Zinc Pty Ltd. A former wartime air base at Batchelor some 8 kilometres was used a the site for a new town.

Production from the White's open cut area of the mine started in 1953 (some underground mining had occurred here from 1950 to 1953) and the treatment plant commenced in 1954. Dyson's open cut was mined in 1957-58 and some ore was mined in 1958 from the Mt Burton open cut. Ore was stockpiled and progressively treated to complete the CDA contract. Territory Enterprises discovered the Rum Jungle Creek South orebody 3 kilometres west of Batchelor in 1960. The Commonwealth Government decided to develop this orebody in 1961 but the CDA contract expired in January 1963. Stockpiled material mined up until 1971 was stored at AAEC at Lucas Heights south of Sydney. This Commonwealth stockpile of about 2 000 tonnes of yellowcake was not sold until 1995 for $57 million (Budget Statements 1995-96, Budget Paper No 1, AGPS, Canberra, 1995).

The uranium treatment plant used an acid leach and ion exchange process until 1962 when the ion exchange process was replaced with solvent extraction and magnesia precipitation to treat the Rum Jungle Creek South ore. Tailings were released into a poorly engineered shallow dam initially and after 1958 were put into White's pit. Furthermore, mining of the copper and lead orebodies at Rum Jungle outside of the White's pit area necessitated the diversion of the East Finniss River.

When the Rum Jungle orebodies were nearly exhausted the AAEC undertook studies to identify the extent and degree of environmental damage and likely sources of pollution. On completion of mining in 1971 it was decided by the Commonwealth Government that funds should not be made available for any rehabilitation, so the area was simply left. The abandoned Rum Jungle mine soon became one of Australia's most notorious pollution problems, due to oxidation of sulphides by bacteria and the consequent release of acid and metals into the East Finniss River. The monsoonal climate and 1500 mm rainfall coupled with the pyritic mineralisation in the area created ideal conditions for the generation of Acid Mine Drainage (AMD).

An initial attempt to clean up Rum Jungle was made in 1977, which led to the setting up of a working group to examine more comprehensive rehabilitation. A $16.2 million Commonwealth-funded program commenced in 1983. A supplementary $1.8 million program to improve the Rum Jungle Creek South waste dumps commenced in 1990.

Table 1 : Production of Uranium from Australian Mines which are now closed.

Mine Period Ore Milled

tonnes

Grade U3O8

Per Cent

Production U3O8

tonnes

Radium Hill 1954-62 970 000 0.11-0.15 850
Rum Jungle 1954-71 863 000 0.28-0.41 3 530
Mary Kathleen 1958-63 2 900 000 0.15 4 080
Mary Kathleen (2) 1975-82 6 300 000 0.10 4 802
Moline (Mill Only) 1959-64 128 000 0.35-0.68 520
Rockhole 1959-62 13 500 1.12 138
Nabarlek 1979-88 600 000 2.0 10 858

Source: Former Australian Uranium Mines, Uranium Information Centre

Mary Kathleen, Queensland, 1958-1982

Mary Kathleen is located about half way between Mount Isa and Cloncurry, in far north west Queensland. The deposit was discovered in 1954 by prospectors from Mount Isa. Mining at Mary Kathleen commenced at the end of 1956 and the treatment plant was commissioned in June 1958. A contract was signed with the United Kingdom Atomic Energy Authority (UKAEA) in 1956 by the developers of Mary Kathleen to supply U3O8. The mineralisation at Mary Kathleen was mainly a rare earths orebody containing uranium (3.0% rare earth oxides and 0.025% thorium oxide). While the mine was in production unsuccessful attempts were made to find markets for the rare earths as a co-product. The first phase of operation from 1958 to 1963 at Mary Kathleen treated 2.9 million tonnes of ore at an average grade of 0.13 per cent to yield 4 500 tonnes of U3O8 of uranium concentrate (yellowcake - ammonium diuranate) containing 3460 tonnes of uranium. Initially the process was the conventional sequence of crushing, grinding, leaching with sulfuric acid, counter-current decantation, followed by ion exchange and extraction and drying.

Tailings were emplaced in a 12 hectare tailings dam in a small valley west of the plant. Overflow was directed into an evaporation pond of some 60 hectares. The supply contract was filled faster than the nine years originally envisaged, consequently in the mine closed in October 1963 and the plant was put on care and maintenance. Some 2.8 million tonnes of 0.148% ore was identified at the end of the first phase of operations were still accessible by open pit mining, containing 4 246 tonnes of U3O8.

Contracts with utilities in Japan, Germany and USA for 4 740 tonnes of U3O8 from Mary Kathleen were negotiated early in the 1970s and recommissioning began in 1974. The Australian Atomic Energy Commission underwrote development, obtaining a 42% holding in the company. The ion exchange section of the processing plant was replaced with a more effective solvent extraction process and the mine and mill reopened in February 1976 at a cost of $26 million. The mine was depleted at the end of 1982 and ceased operation after 4 802 tonnes of uranium oxide concentrate had been produced in its second phase of operation.

The conditions pertaining to 1954 leases issued for Mary Kathleen were minimal by today's environmental standards. The company, however, took the view that it should conform to relevant current (1976) environmental and occupational health standards. Prior to the 1976 recommissioning a full environmental impact study (EIS) was undertaken. The EIS incorporated a rehabilitation plan for the 64 hectares of waste dumps, 29 hectares of tailings dam and 60 hectares of evaporation ponds. Mary Kathleen became the site of Australia's first major rehabilitation project of a uranium mine. Rehabilitation was completed at the end of 1985 at a cost of some $19 million. This work won an award from the Institution of Engineers Australia for environmental excellence in 1986.

South Alligator mines, Northern Territory, 1959 to 1964

The first formal grazing right over land along the upper reaches of the South Alligator River were granted in 1878. The Anglo French company gained mineral exploration rights over the area in 1896. The South Alligator Valley minerals field, contains at least 14 uranium deposits. Early deposits included El Sherana, Coronation Hill and Palette which were mined variously for gold, uranium and other metals

The first of these mines was discovered in 1953, and this was followed by a series of other discoveries. Two companies, United Uranium NL and South Alligator Uranium NL, were principally involved in the area, each with its own treatment plant drawing upon ore from different mines. United Uranium NL negotiated a contract with the US Atomic Energy Commission for the sale of up to 200 tonnes of pitchblende ore and concentrate from the El Sherana mine. A concentrating plant began operation in October 1956 and some 150 tonnes of pitchblende concentrate containing 70 tonnes of uranium was produced in 1956-57 and was supplied through the Combined Development Agency. The residues from this, containing 1.15% (or 1.5%) U, were sold to the AAEC at Rum Jungle.

United Uranium NL and South Alligator Uranium NL contracted with the UK Atomic Energy Authority in 1958 for the supply of uranium oxide from the South Alligator mines. United Uranium then purchased the North Hercules gold plant at Moline, 50 kilometres east of Pine Creek (and about 65 kilometres from the South Alligator mines) and started converting it for acid leaching and solvent extraction of uranium oxide with magnesia precipitation. The plant was commissioned with an annual capacity of about 130 tonnes U3O8 in May 1959, by which time there was a substantial stockpile of ore awaiting treatment.

South Alligator Uranium NL was meanwhile continuing underground exploration at its Rockhole prospect, and in 1957 United Uranium discovered the Coronation Hill uranium orebody. In 1958 South Alligator Uranium commenced construction of a small treatment plant at Rockhole Creek for 50 tonnes U3O8 per year, using the same process as at Moline. This was commissioned in September 1959. The 118 tonne contract with UKAEA was quickly filled, so the mine was closed in 1961 and treatment of the stockpiled high-grade ore was completed soon after. Rockhole Creek plant was reopened in June 1962 for three months to produce 24 tonnes of uranium oxide for sale on the open market. The plant was then sold and partly dismantled. A total of 13 500 tonnes of average 1.12 per cent U3O8 ore had been treated by the plant. In 1963 United Uranium treated 15 000 tonnes of 0.69 per cent U3O8 ore at Moline, a little over half from underground workings at the El Sherana West mine and the balance from open cut mines including Coronation Hill (mined 1957-1964). Exploration continued, but reserves were dwindling and the company purchased all the NT mining titles and the plant from the former South Alligator Uranium.

The Moline uranium plant finally closed in August 1964, having completed its contract with the UKAEA involving the supply of 520 tonnes of uranium oxide. The Moline plant had treated 128 000 tonnes of 0.35-0.68 per cent U3O8 ore in a little over 5 years. The plant was subsequently converted to extract gold from the uranium tailings, which ended in October 1965.

Nabarlek, Northern Territory, 1979 to 1988

Queensland Mines Ltd discovered the small high grade Nabarlek deposit in May 1970. Nabarlek is located 15 kilometres east of Oenpelli, just inside Arnhem Land in the East Alligator River region. Agreement was reached with the Northern Land Council and other Aboriginal groups to enable development of the deposit by Queensland Mines Ltd in 1979. An Environmental Impact Statement was prepared prior to approval of the mine. The Nabarlek 1 orebody was mined out in 4 months of the dry season producing 600 000 tonnes of 2 per cent U3O8 grade ore stockpiled for treatment from 1980. Mining of Nabarlek also required the relocation of about 2.3 million tonnes of waste. Over the period 1981 to 1988 a total of 10 858 tonnes of uranium oxide was produced at 1 500 tonnes per year. Uranium from Nabarlek was sold to Japan, Finland and France.

Nabarlek then remained one of the three uranium mines approved under the ALP "three mines policy" applied by the previous Federal Labor Government. Accordingly it had considerable value if further ore reserves were found on its leases, or even nearby. The Nabarlek 2 deposit is documented but not believed to be an economic proposition.

Pioneer International Ltd, the parent company of Queensland Mines, which is virtually defunct, wrote off Nabarlek except for a liability in its balance sheet to allow for rehabilitation of the site. Cogema Australia has a 50 per cent interest in the Nabarlek exploration leases.

Part of the ore processing plant was sold in 1994. It was cleaned and decontaminated to very stringent standards chemically and radiologically before removal. Remaining equipment was dismantled and buried in the mine pit, with all tailings and evaporite, as well as building foundations. Waste rock completed the filling of the pit, and a layer of waste rock was applied over its surface as an erosion-resistant cover. Stockpiled topsoil completed the site landscaping earthworks. The area was then seeded with a mixture of grass and a wide range of native species in accordance with the authorised Decommissioning Plan. Rehabilitation work was completed at the end of 1995. After the onset of the wet season vegetation cover was found to be good, with no ponding and little erosion. Monitoring and research will continue, and Nabarlek represents the first rehabilitation of a uranium mine in Australia according to current principles and practice.

OPERATING URANIUM MINES

There are two operating uranium mines in Australia. This has been the situation since closure of the Nabarlek operation in 1988. Both mines are planning major expansions in the near future. Ranger is moving to a new orebody (Number 3) and Olympic Dam is planning a general expansion including copper production. Number 2 orebody at Ranger will not be mined due to Aboriginal considerations.

The mining of uranium has specific impacts on the environment due to the radioisotopes produced and the possible impacts of these on plants, animals and humans. The movement of long lived radioisotopes such as radium226 from uranium mines is governed by the ecological, chemical and physical characteristics of the tailings environment. Some aquatic species can concentrate these radioisotopes, with further accumulation in the food chain. Studies from Canada, in particular, show that lead and thorium are taken up by algae, while uranium is concentrated in higher freshwater plants. The majority of effects, however, from well regulated uranium mines, are similar to those of other mines, that is aesthetic effects and the development of previously undeveloped areas. The inevitable results such as new roads mill works, mine workings and increased concentrations of humans are the major impacts.

Olympic Dam, South Australia

The Olympic Dam (Roxby Downs) mine is located 520 kilometres north west of Adelaide in South Australia. Discovery of the orebody was by WMC geologists in 1975 under 350 metres of non ore bearing rock. The mine commenced operations in 1988 and is one of the world's largest mineral resources. Copper is the main product from the mine with significant economic quantities of contained gold, silver and uranium.

Uranium production from Olympic Dam was 1 083 tonnes of U3O8 in 1994-95. The WMC owned mine is forecast to maintain a stable output of around 1 500 tonnes of U3O8 per annum in 1995-96 and 1996-97 (Australian Commodities, ABARE, Canberra, March Quarter, 1996). WMC has approved a $1 billion expansion of the Olympic Dam mine which will lift the company (not the mine) into one the world's top ten copper producers at 200 000 tonne per annum ("Olympic effort to land WMC in copper elite", AFR, 6 Feb 96). Production at the mine would lift from 84 000 t to 150 000 t of copper and unit production costs would decrease. Direct royalties to the South Australian government will double to at least $25 million (Pollock J., WMC's Olympic Dam Expansion a boost for South Ausstralia, Paydirt July 1996). The mine has a 580 million tonne resource which will last at least 150 years. The environmental aspects of the expansion were approved by the then Minister for Environment, Sport and Territories, Senator John Faulkner.

The expansion will require additional water resources for the mine, around double the volume that is currently drawn. The area is arid and surface water resources are limited. Production water is drawn from the Great Artesian Basin for the current operations from Borefield A. Borefield A is located 100 kilometres to the north east of the mine site. Current production water requirements are 7 megalitres per day. The expansion will require additional water from Borefield B. The original EIS for Olympic Dam considered the expansion at Borefield B. Borefield B is located 50 kilometres to the north east of Borefield A and is currently undeveloped. Water requirements for the mine outlined in the 1982 EIS were estimated at 33 megalitres per day. Water requirements for production will not be as large as those estimated for the expansion, due to water conservation measures introduced at Olympic Dam in the last few years. Estimates for water extraction from Borefield B are around 20 megalitres per day and decreased extraction will be required from Borefield A.

Environmental concerns regarding the additional withdrawal of water revolve around `mound springs' in the area. Mound springs are locations where groundwater escapes under pressure from the Great Artesian Basin. Over long periods of time, mounds and small ponds build up around the springs. Endemic species have evolved in some of the longer lived mound springs. The objections to additional withdrawal of water from the Great Artesian Basin by WMC are due to the concern that reduced water pressure in the basin will result in significantly reduced water flow into the mound springs. Flora and fauna associated with the springs could be at risk should the water resource be removed or substantially reduced.

Recharge of the Great Artesian Basin occurs along the Basin's eastern margin, on the western slopes of the Great Dividing Range. The distance that ground water must cover accounts for the slow recharge rates and the `age' of the water being extracted. The recharge characteristics of the Great Artesian Basin were carefully considered in the 1982 EIS. Mound springs are locations where water under pressure escapes from the Great Artesian Basin, over times mounds and small ponds build up around the springs. Endemic species have evolved in some of the longer lived mound springs. The objections to additional withdrawal of water from the Great Artesian Basin by WMC are due to the concern that reduced water pressure in the basin will result in significantly reduced water flow into the mound springs. Flora and fauna associated with the springs would be at risk should the water resource be removed or substantially reduced. Other considerations related to mound springs may form part of a World Heritage nomination for the Lake Eyre Region as well as National Estate considerations.

The South Australian Government carried out an Environmental Review and a major study into the environmental impact of the expansion into Borefield B in conjunction with WMC Ltd. The guidelines for the assessment of Borefield B require WMC to undertake field studies, laboratory work and modelling investigations to determine the nature and characteristics of mound springs, vascular and non vascular vegetation, vertebrate and invertebrate fauna, water chemistry, water flow and draw down. According to the Minister of Environment, Sport and Territories, Senator Faulkner, the South Australian assessment process will evaluate the effects of the proposed development of Borefield B on springs throughout the region (Senate Hansard, 22 August 1995, Q 2203). Five recommendations were made on the issue, but overall the project was approved by Senator Faulkner and Senator Collins (Minister for Primary Industries and Energy). The South Australian processes covering the mine expansion were viewed as adequate by the Commonwealth authorities (pers comm with Sam Walker, SA Department of Mines and Energy, 28 March 1996). On 29 January 1996 Senator Collins indicated that export permits for the expansion in uranium production would be granted subject to the meeting of the recommendations.

A further environmental concern with Olympic Dam is due to a seepage from the Olympic Dam tailings impoundment into underlying groundwater announced by WMC during 1994. Water from the impoundment leaked into an underlying aquifer to form a “mound” under the tailings impoundment. The receiving aquifer is more saline than sea water. Monitoring of the aquifer has not located any radionuclides from the tailings impoundment in the ground water. This is probably due to adsorption of radionuclides onto clays in the permeable layers.

The seepage from the tailings impoundment was identified by WMC and also by monitoring by the SA Department of Mines and Energy under the normal regulatory processes. A committee of inquiry by the South Australian government found that the leak was a result of a lack of supervision. The report recognised that the firm acted quickly and announced the leak once it was detected (lack of supervision blamed for Olympic Dam leak, The AusIMM Bulletin, No 5 August 1996.) According to the SA Department of Mines and Energy the problem has been addressed appropriately. Engineered modifications to the impoundment and residue emplacement meet world's best practice (Personal Communications with Mr Sam Walker, Department of Mines and Energy South Australia 28 March 1996). WMC has installed evaporation ponds at the tailings impoundment to allow dry layers of tailings to build up. These layers are less permeable than those deposited under the prior wet deposition system. The ground water mound is being pumped out through bore holes and evaporated off in the tailings process system. The mine eventually intends to install impermeable geotextile membranes at the impoundment to fully solve the problem. The timing for the installation depends upon a reshaping of the tailings impoundment.

The underground nature of the operation results in relatively reduced environmental concerns in the vicinity of the mine, particularly with regards to aesthetic impacts. According to the main environmental groups in South Australia (Personal Communications with Ms Cherry Hoyle, Friends of the Earth 27 March 1996 and Professor Denis Matthews of the Conservation Council 27 March 1992), the main environmental problems with the Olympic Dam uranium mine are :

the mine produces uranium, both environmental groups strongly expressed their absolute opposition to mining of uranium regardless of the safeguards in place;

under the South Australian system there is no independent body which monitors the mine; the Commonwealth Office of the Supervising Scientist (OSS) provides a much more appropriate model in the Northern Territory;

there is no public scrutiny of the mine's operations, whereas in the Northern Territory the OSS provides a measure of public scrutiny and information dissemination;

there was a major leak of water from the Olympic Dam tailings impoundment, announced by the company in 1994;

any expansion of the mine would require the withdrawal of additional water resources from the Great Artesian Basin, essentially a non renewable resource;

the indenture for the mines operation is out of date and does not represent more recent thinking;

creation of divisions within remote Aboriginal communities as a consequence of mining.

(Personal Communication with Cherry Hoyle, Friends of the Earth, 27 March 1996 and Dr Denis Matthews of the Conservation Council of South Australia)

Ranger, Northern Territory

Ranger is located about 230 kilometres east of Darwin in the Alligator Rivers uranium field. Ranger is the only operating uranium mine in the Northern Territory. The Ranger mine lease is within the Kakadu National Park and World Heritage Area, but predated both and is excised from them. Currently the Ranger mine is owned and managed by ERA Ltd., an Australian corporation owned mainly by North Ltd. Ownership of the land is by the Mirrarr Kundjeyhmi Clan of Aboriginal people. Consequently rental ($200,000 per year) and royalty (4.25 per cent of gross sales) payments are made by the mine to the Northern Land Council. The Northern Land Council subsequently makes a proportional payment to the Aboriginal land holders (The Ranger Operation, Information Sheet, ERA, November 1992).

Mining at Ranger commenced in 1980 following the Commonwealth's Ranger Inquiry (Fox Inquiry) and an Environmental Impact Statement. The Fox Inquiry was set up in 1975 to investigate and advise on both uranium policy in general and on uranium mining in the Alligator Rivers area in particular. The Inquiry lasted almost two years, heard 303 witnesses and produced two reports. A key result of the Fox Inquiry was the establishment of the Office of the Supervising Scientist (OSS). The OSS provides independent scientific assessment and monitoring at Ranger, and is financed by a levy on Rangers uranium production.

Issues associated with development in national parks must be considered in any analysis of uranium mining in Kakadu National Park. The park was created in 1979 with an initial area of 6 144 km2 (Stage 1), a further 6 929 km2 was added in 1985 (Stage 2). The Federal Government in 1986 said that mining would be permitted under certain conditions, but in 1987 the Federal National Parks Wildlife Conservation Act was amended to ban exploration and mining. The park was extended by 4 479 km2 and the Conservation Zone of 2 252 km2 (including Coronation Hill) was declared (Stage 3). The land is leased from the Kakadu and Jabiluka Aboriginal Land Trusts. World Heritage Listing of the area was obtained subsequent to the declaration of each stage of the National Park.

Production from the Ranger mine in 1994-95 was 1 549 tonnes of U3O8. Mining of the first ore body, Ranger 1 is complete and mining is planned to commence at Ranger 3 in 1997. The resource at Ranger 3 is adequate for at least 20 years mining. (No mining is planned for Ranger 2 as a consequence of Aboriginal considerations.) The empty Ranger 1 pit will be converted into a tailings impoundment during 1996.

ERA submitted an application to mine Ranger Orebody No. 3 to the Northern Territory Department of Mines and Energy on 1 March 1996. While the OSS raised a few specific issues it had no fundamental problem with the application because it felt the operation of the new orebody would not be different from the mining and processing of ore from the existing orebody. One issue relates to the control of groundwater flows from the orebody to Magela Creek. Activities in the Ranger Project Area are exempted from the Administrative Procedures of the Environment Protection (Impact of Proposals) Act 1974 by a gazettal in 1977.

The planned development at Ranger relies on the use of the worked out Ore Body number 1 pit for tailings disposal. The key engineering concern with this proposed method of disposal is adequate `thickening'. Thickening is the process by which water is removed from the tailings and the volume of the waste is reduced. It is the volume reduction which concerns the mine's engineers, without this process further tailings developments would be required at Ranger at additional cost. A key difference between disposal in a tailings impoundment and an old mine is access to the water table. Engineered solutions such as concreted seals and grout curtains go some way to prevent the ingress of water of egress of contaminated material but these risks are increased relative to the `dry' impoundments above the water table.

Over sixteen years of mining Ranger has demonstrated effective management of environmental matters. The mine operates under strict Commonwealth and Northern Territory legislative control. The OSS continually monitors and reports on activities on the site. The mine's success in environmental management probably rests as much, if not more on the efforts of the OSS as it does on the mine management. The environmental impact of Ranger was demonstrated in a Question upon notice to the Minister for Resources on 1 September 1993. Mr Lee answered the question on 13 December 1993 saying that “I am not aware of any serious occupational health and safety concerns arising from uranium mining operations”. Mr Lee also quoted the OSS, “both the mines at Ranger and Nabarlek are well run and tightly regulated and the Supervising Scientist has consistently reported that, while some effects are detectable, the environment is not being harmed by these operations”. (At the time Nabarlek was in the process of decommissioning and rehabilitation). The transcript of this question and answer is attached. The situation has not altered since that time, the most recent OSS report states that “no significant effects upon the environment were recorded” (Supervising Scientist for the Alligatoar Rivers Region, Annual Report 1994-95.)

The key issues which have arisen with the Ranger operation are related to water management on site. The Ranger tailings impoundment is 1km by 1km in area, around 100 hectares. The system with the tailings impoundment is known on the site as RP3 (Retention Pond 3). Three other systems are present at the mine RP1 - bushland and disturbed area rainwater run off; RP2 - working area run off; and RP4 - waste dump run off. Water from RP2 and RP4 is used a secondary supply for the mine and excess is removed by evaporation and sprinkling. Water from RP1 flows through wetlands filter systems and flows over a spillway to Coonjimba Creek. RP1, RP2 and RP4 have relatively minor levels of contamination; RP3 is the highly contaminated mine process water.

The tailings impoundment was created by a raised bund wall around its perimeter. Water from the impoundment is never released from site due to the presence of radionuclides and heavy metals. Water in the RP3 tailings impoundment is from the 'dirty' part of the mining operation, water used to wash trucks, oily water from the heavy workshops, run off from the acid plant and the sulphur stockpile. Management of water from the tailings impoundment is achieved by repeated recirculation and reuse and then eventually evaporation during the dry season. Significant leaks from the RP3 system are detailed below. The management of tailings at the Ranger mine site has required and continues to require extensive scientific study. Minimisation of the volume required for tailings disposal is achieved by disposal into the impoundment on `beaches' rather than into the deeper parts of the impoundment. This `thickening' is an important part of the planning for the future use of Ranger 1 (the completed ore body) as the future tailings impoundment. When full the tailings impoundment will be dried out, stabilised and capped with a cover of clay, rock and vegetation. Once completed the site will appear as a low hill rising to a maximum height of 24 metres above the surrounding landscape.

The Ranger area is monsoonal (wet and dry seasons) with an annual average rainfall of about 1 800 millimetres. The wet season lasts from October to April in most years. An issue over the released of water from did develop in 1995, due to a higher than usual rainfall in the area. Some 1 million megalitres more than can normally be disposed by the existing system in an average year accumulated in the mine project area. The build up of water was entirely within the RP2 - working area run off system not the highly contaminated RP3 - tailings impoundment system. ERA applied to release this water under controlled conditions to Magela Creek, that is, releases would only occur when Magela Creek was flowing at prescribed levels. Permission for the release was granted, but community concern was raised by Aborigines living downstream. The mine took these concerns into account and with held the release. Following negotiations between the mine and the Aborigines a $500 000 wetlands filter system was proposed and developed. Uranium chemistry is such that it is taken out of solution rapidly when exposed to clays, onto which the uranium absorbs. As a consequence, water which has passed through the wetlands is effectively filtered before release. Measured levels of uranium in the water released are well below the prescribed standard.

No single disastrous event has occurred at the Ranger mine. Concerns have been raised that while no single event is major, cumulative effects may occur. The OSS recognised in 1991 that the expected environmental effects of a large operating mine are beginning to be recognisable outside the immediate environs of the mine site (Supervising Scientist for the Alligataoar Rivers Region, pp 14-15 Annual Report 1990-91.) No impacts to date have, however, reached outside of the mine lease area which surrounds the mine site.

On 11 July 1984, 200 cubic metres of water leaked outside the Ranger Restricted Release Zone (RRZ). (The RRZ is an area from which releases must be controlled and documented.) The water leaked from a parted coupling in the pipeline that returns seepage back to the impoundment from collection sumps around the tailings impoundment. The OSS stated that most of the water infiltrated back into the underground collector system (Supervising Scientist, Annual Report 1984-85, Appendix 4.) During the wet season on 27 February 1992 a high rainfall event occurred which resulted in water from the high grade ore stockpile escaping from its containment sump. The water contained significant concentrations of uranium and flowed into Georgetown Creek, then into Magela Creek. The OSS concluded that the quantity of uranium lost to the environment would have caused no harm to human health. The concentrations of uranium that eventuated in Magela Creek from this incident were too low to have had an ecological effect (Supervising Scientist, Annual Report, 1991-92, Appendix 9.) The most significant recorded radiation exposure event at Ranger occurred on 5 July 1992. Two workers were exposed to yellowcake in the packaging room. Assessments revealed that one worker's radiation dose was virtually at the annual limit. Supervision and operating practice was tightened to avoid further incidents.

CONCLUSIONS

Two uranium mines operate in Australia at the present time, Ranger in the Northern Territory and Olympic Dam in South Australia. The Olympic Dam mine is owned by WMC and is situated in a remote arid part of South Australia. The key issues raised by groups opposing mining at Olympic Dam relate to water consumption and tailings management. The water consumption issues are not specific to Olympic Dam's mining of uranium - these would be of concern if uranium were not mined. The leak of water from tailings impoundment into an underlying aquifer represents a serious breech of quality control at the mine. The consequences of the leak have not proved to be dramatic and radionuclides have not reached the aquifer which is hyper saline in any case.

Breeches of quality control have occurred at the Ranger mine in the Northern Territory, as recognised by the Office of the Supervising Scientist. The environmental impacts of the mine, however, have not been significant outside of the minesite.

The majority of concerns over mining with both the operating uranium mines in Australia, would be pertinent whether or not the mines were producing uranium. Water release issues, water consumption issues, dust release, road building, infrastructure construction and transport impacts occur with all mines. The fact that the mines produce uranium heightens their presence in terms of public perception and galvanises opposition to mining. The key opposition to the mining of uranium is just that, uranium. A philosophical divide remains in the Australian community (as with those overseas) over whether nuclear power should be employed as an energy source. Nuclear reactors are not likely to be developed in Australia (unless dramatic changes occur in international responses to climate change and greenhouse gas mitigation) and, as a result, the key focus for those opposed to nuclear power remains the mining and export of uranium.

 

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