The Jabiluka mineral lease, 230 km east of Darwin and covering 73 km2, is owned by Energy Resources of Australia Ltd (ERA), a Rio Tinto group company. It adjoins the northern boundary of the Ranger Mineral Lease. The Jabiluka lease is surrounded by Kakadu National Park, which has been inscribed on the World Heritage list due to its outstanding natural and cultural values. Jabiluka is in the East Alligator River catchment, adjacent to Ngarradj (Swift Creek), which flows into the Magela floodplains to the north.
Development work at Jabiluka took place in the late 1990s but ceased in September 1999, at which time the site was placed in an environmental management and standby phase that lasted until 2003. During 2003 it was agreed that the Jabiluka site would not be mined and the site was placed in long-term care and maintenance. ERA has entered an agreement with Traditional Owners, the Mirarr, stating that no further development will occur at Jabiluka without their approval. Whilst in long-term care and maintenance, revegetation activities have been undertaken by ERA, however, final closure of the site is not anticipated in the short-term given that lease expiry will not occur until August 2024.
Aerial view of the rehabilitation and vegetation regrowth on the Jabiluka minesite from 2006 to 2018
Revegetation of the disturbed parts of the Jabiluka mineral lease aims to recreate a vegetation community of local native plant species of similar density and abundance to that existing in undisturbed, adjacent areas.
Between 2006 and 2014 approximately 15,500 seedlings were planted across the Jabiluka mineral lease, including the former Jabiluka mine footprint and the former Djarr Djarr exploration camp site. Hot fires originating off the lease burnt through the revegetated areas of the Djarr Djarr exploration camp site in 2007, 2008 and 2010, resulting in significant vegetation mortality.
Vegetation surveys carried out by ERA during October 2015 showed that plant mortality rates for vegetation planted in 2013 were around 50%, increasing to around 80% for vegetation planted in 2014. The 2015 survey also demonstrated that natural recruitment is occurring, contributing to up to 85% of the total number of stems at the site.
ERA uses herbicide to actively manage weeds at the Jabiluka mineral lease. Recent survey results show a decrease in weed density at both Djarr Djarr and Jabiluka. ERA also undertakes annual fuel reduction burning around the Djarr Djarr and Jabiluka sites to reduce the effects of wildfires on the revegetated areas.
ERA continues to monitor water quality in groundwater and surface waters upstream and downstream of the Jabiluka site in accordance with the Jabiluka Authorisation. Overall, the monitoring results reported during the 2017-18 wet season remain within historical ranges reported in previous wet seasons, and there has not been any evidence of off-site environmental impacts.
The Koongarra uranium deposit is found 30 km south of Ranger and 3 km east of Nourlangie Rock in a valley bounded by Mount Brockman outlier and the Arnhem Land plateau. The orebody lies entirely within the catchment of Koongarra Creek which feeds the Nourlangie Creek, part of the South Alligator River catchment. The estimated uranium (U3O8) yield from the two orebodies is estimated to be 14540 tonnes containing an average grade of 0.8% of uranium.
The deposit was discovered in 1970 by Noranda Australia Ltd, and in 1976 Noranda applied for a Special Mining Lease covering the 12.5 square kilometer deposit.
In 1977, the Ranger Uranium Environmental Inquiry report recommended the declaration of Kakadu National Park under the National Parks and Wildlife Act 1975 (NPWCA), and this included the Koongarra uranium deposit. The inquiry opposed mining the Koongarra deposit unless it could be demonstrated that there would be no environmental damage.
In announcing its August 1977 decision to allow mining of the Ranger deposit, the Fraser government decided that the Koongarra Special Mining Lease area would be excluded from Kakadu National Park.
Stage 1 of Kakadu National Park was listed as World Heritage in December 1981, but the Koongarra project area was excluded from this listing.
Despite gaining approval from Government and negotiating agreement with Traditional Owners through the late 80s and early 90s, the project was never developed. In 1995, the French Company, Areva, acquired the Koongarra project and, following a 5 year moratorium that was placed on the lease, resumed negotiations with Traditional Owners and the Northern Land Council.
In 2007, Jeffery Lee, senior Traditional Owner of the Koongarra uranium deposit, publicly stated that he would never allow Koongarra to be mined, and wanted the area included in the World Heritage listed National park to ensure its protection forever.
In 2010 the Northern Land Council wrote to the then Minsiter for the Environment, Heritage and the Arts, Peter Garrett, on behalf of Jeffery Lee, offering the Koongarra land for inclusion in Kakadu National Park.
In 2011 the World Heritage Committee approved the inclusion of the Koongarra project area into the Kakadu National Park World Heritage area, and on the 6th of February 2013 the Government repealed the Koongarra Project Area Bill, thereby incorporating the area into Kakadu National Park.
The Nabarlek uranium mine, located 280 km east of Darwin, operated from 1979 until 1988. The small and concentrated orebody was mined in a single 143-day campaign during the 1979 dry season. The ore was stockpiled on a specially prepared site while the mill was being built, and then processed over the next nine years. The mine was decommissioned in 1995 and the site underwent rehabilitation.
The Nabarlek mine exhibits some interesting features, demonstrating unique approaches to mine site rehabilitation. A significant feature of the operation was the return of tailings directly to the mined out pit. It is still believed to be a unique occurrence of uranium mining in the world. This was in accordance with the Environmental Requirements of the Australian Government - a set of conditions put in place to ensure that the operation gave the environment the highest possible level of protection.
The development of plans for the decommissioning and rehabilitation of Nabarlek commenced at the outset of mining operations. These plans, which consisted of many components, underwent a series of reviews and updates to take into account changes in mine development, results of site-specific research, and new technologies. The shape of the final domed cover over the pit was based on research into the landforms in the area. The rehabilitation objective, as agreed with the Traditional Owners and the supervising authorities, was to establish a landscape that matched as closely as possible the surrounding areas and would permit traditional hunting and gathering activities to be pursued.
In early 2008 Uranium Equities Limited (UEL) bought Queensland Mines Pty Ltd (QML), thereby acquiring the Nabarlek lease. In 2018 UEL changed their name to DevEx resources. Since 2008, DevEx has undertaken extensive exploration on the Nabarlek lease and assumed responsibility for management of the rehabilitated areas at the site. The exploration activities and the performance of the ongoing rehabilitation and revegetation program continues to be monitored and assessed by SSB, the regulator and key stakeholders including the Northern Land Council.
South Alligator Valley mines
Former uranium mill in the South Alligator Valley
The high mineral prospectivity of the Alligator Rivers Region, particularly for uranium, is evidenced by the 13 or so former uranium mines and numerous mineral deposits that are located in the upper South Alligator River Valley. Although there are no mines currently in operation in this area, in the past it has been a highly active area with numerous deposits, many of which were mined during the 1950s and 60s.
Environmental standards and practices during the 50s and 60s are not comparable with those currently in place and many of these older sites have been subject to some level of environmental rehabilitation in recent times.
In 1986, a survey of abandoned mines in the South Alligator Valley was undertaken by the Commonwealth and in 1988, a follow up survey produced a series of proposals for the rehabilitation of the minesites. Due to funding constraints, complete rehabilitation was not possible. However, it was decided that as a priority, a program of physical and radiological hazard reduction would be carried out for the safety of National Park users. This involved identifying areas where radiation doses exceeded permitted levels for public exposure and arranging for the appropriate disposal of affected material. The work was completed in 1992 with target protection levels successfully achieved. Annual erosion inspections are ongoing and radiation surveys are carried out every three years.
El Sherana radiological containment under construction, South Alligator Valley
In 2006, the Commonwealth Government provided $7.4 m over four years to Parks Australian North to clean up all remaining sites within the South Alligator Valley to an acceptable standard. A containment facility was constructed in 2009 at the old El Sherana airstrip for the final disposal of historic uranium mining waste recovered from several sites throughout the South Alligator River Valley. Annual inspections by the Supervising Scientist Branch are ongoing.