Rössing Uranium is committed to protecting the environment in which we operate. Measures include a wide range of preventative monitoring activities. We have a particular focus on water management and monitoring, especially in light of the extreme rainfall associated with the Erongo Region’s water-scarce, hyper-arid climate. We have a strong history of engagement and co-operation with our regulators and other stakeholders to ensure that the environment remains protected.
Above: Biodiversity advisor, Loide Hausiku, checks the condition of a Euphorbia virosa in the mining licence area of the mine with the Tailings Storage Facility in the background. Left: While it is not possible to extract mineral resources essential for modern life without impacting on the environment, we adjust the way we operate to reduce our impact on ecosystems and biodiversity as much as possible.
We manage impacts on the environment with guidance from, among others, Namibian legislation, the ISO 14001 Environmental Management System, Rio Tinto's performance standards and international best practices. Through transparent reporting we provide our stakeholders with the assurance that our environmental impacts are monitored and the necessary mitigation measures are in place to keep our environmental impacts minimal.
Our environmental management performance, measured against set objectives and plans, is discussed below.
Responsible water management
Water management at Rössing Uranium is guided by a formal water strategy and management plan, developed according to the Rio Tinto performance standard Water quality protection and water management and supported by Rio Tinto’s Water use and quality control guidance notes.
The notes cover all activities related to water abstraction, dewatering, transport, storage, usage (potable and process) and treatment, and involves surface water (including run-off), impounded water and ground water. The intent of the standard is to ensure effcient, safe and sustainable use and protection of water resources and ecosystems.
In addition, Rössing Uranium adheres to all water-related aspects pertained in the Constitution of the Republic of Namibia. To that effect, we operate with a Waste Water and Efﬂuent Disposal Exemption Permit 674 (valid until December 2020) and Water Abstraction Permit 10200 (valid until March 2019).
Knowing that our water requirements are substantial, our focus is on the sustainable and accountable use of this scarce and valuable resource, with minimal adverse effect on the environment.
We carry out various continuous monitoring, which include:
- taking frequent ﬂow-meter readings at various points in the Processing Plant to provide a continuous overview of our water balance data;
- taking frequent water level measurements on our Tailings Storage Facility (TSF) and numerous monitoring locations across the mine site, extending to the Khan and Swakop Rivers; and
- conducting water-quality sampling at various locations (starting at the source, the TSF) which we use to understand changes in water chemistry due to chemical reactions in the heterogeneous environment.
All spillages in the Processing Plant are captured and channelled to a large recycle sump for reuse. Efﬂuents from the workshops are treated to remove oils and sewage is treated in the onsite Sewage Plant. These purifed efﬂuents are used in the open pit for dust suppression.
On the deposition pool (active paddy) of the TSF, water is recycled and reused on a continuous basis in the Processing Plant, minimising evaporation and infltration into the tailings pile. Remaining water that has infltrated is recovered by pumping boreholes and open trenches installed on the facility itself to reduce the volume of underground water within the tailings pile.
Seepage control systems are also employed outside the TSF. They include a surface seepage collection dam to capture water from the engineered tailings toe drains, cut-off trenches in sand-flled river channels, dewatering boreholes situated on geological faults and fracture systems on the downstream, western side of the facility. All systems are designed to lower the water table to the extent that ﬂow towards the Khan River is interrupted. The recovered water is reused in the Processing Plant.
Our water demand is met by the local bulk water supplier, NamWater, via a pipeline from the marine desalination plant at Wlotzkasbaken. The supply of freshwater is an ongoing challenge for our operation due to the cost implications of desalinated water and the disruption in continuous supply.
The total freshwater usage target for 2017 was set at 2.85 million cubic meters (Mm3). The actual consumption of fresh water came to 2.99 Mm3, which is 4.9 per cent above the planned target. The bars in Figure 13 in the next column show that the actual monthly freshwater use was higher than planned during most months in 2017. This relates to the line graph in Figure 13 which shows the water consumption rate per tonne of ore milled. Against the set target of 0.3 cubic metres water per tonne of ore milled, the mine averaged 0.335 m3/t for 2017.
The large volume of freshwater consumption was primarily attributed to a higher water requirement per tonne of ore produced as indicated in Figure 14.
This is mostly due to the high calc content in the ore which requires more water during processing. The commissioning of the new deposition paddies, which inﬂuenced particularly the entrainment and evaporation losses, hindered our recycling efforts during the reporting year.
The increase in freshwater usage per month and per tonne of uranium oxide produced is mostly explained by the high calc content in the ore, which requires more water during processing.
Water-quality management programme
Acknowledging our impacts and its inevitable inﬂuence on the environment, Rössing Uranium established a network of monitoring sites, which begins at the TSF, extending to the Khan and Swakop Rivers.
In 2017 we concluded a large-scale, intense revision of our water quality management programme. It was identifed and deemed necessary to:
- upgrade the infrastructure for our seepage-recovery systems; and
- scrutinise the viability of our existing water-quality monitoring programme.
The structural upgrade on the seepage-recovery system, which involves installation of fully automated, state-of-the-art telemetry systems, is scheduled for commissioning in the beginning of 2018. The system is the last line of defence in a multi-layered seepage recovery mechanism and is designed to limit seepage from the TSF ﬂowing towards the Khan River.
During 2017, and in conjunction with relevant stakeholders, Rössing Uranium evaluated the existing water-quality monitoring approach and came to the conclusion that improvements can be made to the routine sampling schedule (location, frequency and type of chemical analysis) and sampling methodology.
Based on a scientifcally justifed indicator of sulphate concentration greater than 3,000 ppm defning the seepage front, contours were drawn from the TSF incorporating the hydrogeological setting of the area. An adaptive (to seepage-front regression or progression) water-quality monitoring/sampling approach was discussed with the regulator and stakeholders towards the end of 2017 and will be fnalised in 2018. All stakeholders will be involved in the process.
Khan River water use
Saline water from the Khan River aquifer is used for the purpose of haul-road dust suppression in the open pit. A total of 104,755 m3 of water was abstracted from the aquifer during 2017, which is 12 per cent of the permitted 870,000 m3 per year.
Although we abstract a low portion of the permitted volume, we continue to monitor the vegetation and water levels in the Khan River to prevent over-abstraction, based on the ecosystem response.
In compliance with the abstraction permit conditions, annual reports derived from the water-level and vegetation-monitoring programmes are sent to the Ministry of Agriculture, Water and Forestry’s Directorate Water Resources Management.
Air-quality management in mining refers to all the actions Rössing Uranium undertakes to help protect the environment from the harmful effects of air pollution caused by mining activities. Dust is generated during blasting, loading and dumping of ore and waste, as well as during crushing and conveying ore. Winds at speeds above 30 km/h potentially erode fne particles from rock dumps and the TSF and disperse them in the environment. In addition, noise and ground vibrations are created during blasting which is conducted when required, while the machinery deployed in the open pit and the Processing Plant generates noise continuously.
Dust emissions are of concern to residents of Arandis and Swakopmund as affected environments, especially when high-velocity winds occur during the winter months.
To quantify dust fallout and allow mitigation when necessary, a monitoring network is in place. We apply appropriate standards and regulations to assess monitoring results to ensure that the environmental dust is kept within the recommended limits.
Two types of dust are measured: firstly, a very fine inhalable dust invisible to the naked eye that is comprised of particulate matter less than 10 micron (known as PM10), and secondly, fallout dust, which is visible on the ground and comprised of lager particles, including PM10.
The measure of PM10 is the weight of particles less than or equal to ten micrometres in diameter in one cubic metre of air. When inhaled, these tiny particles are not fltered out by the body and therefore reach the lungs.
We monitor PM10 dust levels onsite at three dust monitor stations and at one station in the nearby town of Arandis (see Figure 15, denoted by pink triangles).
The levels measured in 2017 showed that PM10 dust concentrations at all stations were below the adopted World Health Organisation standard of 0.075 mg/m3, except for one month, May 2017 (see Figure 16 on the right hand side).
Environmental advisor, Ann-August Shikongo, takes readings at the mine’s dust monitoring station at Arandis. At the mine and the nearby town of Arandis a monitoring network is in place to quantify dust fallout and allow mitigation when necessary.
The exceedance in May was at the western mine boundary. However, this case was not cause for concern as the WHO standard requires an annual average of 0.040 mg/m3.
Throughout the year, fallout dust is measured at six stations at different locations along the mine boundary (see the yellow dots on the map, Figure 15. The dust-fallout limit is 600 mg/m2 per day with an annual average target of 300 mg/m2 per day. Values measured during 2017 at the six stations ranged between 6 and 87 mg/m2 per day with an annual average of 20 mg/m2 per day (see Figure 17).
All measured deposition rates were well below the selected or adopted South African dust-control regulation.
Noise and vibration
Noise and vibration at Rössing Uranium are monitored through a network of various points and studies. The management of noise and vibration is guided by the Rio Tinto performance standard E6 (Noise and vibration control).
Environmental noise is monitored according to a specifc procedure and reported on a monthly basis to minimise noise to threshold levels and identify events when these levels are exceeded.
Throughout 2017, both air-blast and ground vibration levels have been consistently below the limits of 134 dB and 12.5 mm/s respectively. Blasting is only carried out in the open pit approximately three times per month.
Environmental noise is measured over snapshots of ten minutes. There were four events in 2017 during which noise levels, as recorded at the sampling points on the mine boundary, were above 45 dB(A) and, thus, exceeded the standard (Figure 18).
The events during which noise levels exceeded the standard are not ascribed to the operational activities at the mine, but are the result of natural sounds or passing vehicles in the immediate vicinity of the sampling points.
Mining operations are resource-intensive, consuming land, water, power, fuel, chemicals and construction materials to extract the metal held by the ore body. During the ore mining and metal refning processes, waste materials are produced which consist of mineral wastes in the form of rock and process tailings, and other waste products generated by the services that support the mining process.
During 2017 a total of 24.1 million tonnes of mineral waste were generated by the mine. This includes 9 million tonnes of tailings and 15.1 million tonnes of waste rock. A similar tonnage of waste was generated in 2016. The total cumulative mineral waste stored onsite at the end of December 2017 amounted to 955 million tonnes of waste rocks and 427.1 million tonnes of tailings.
Tailings were deposited on the existing TSF, mainly in the reactivated deposition areas that were prepared in 2015. The tailings footprint extended by 0.6 ha, or 0.1 per cent, into a partially disturbed area immediately north of the facility. In total, 0.69 ha of land was disturbed, including 0.6 ha of tailings impoundment and 0.09 ha of a service track. The rock waste was deposited on top of the existing rock dumps close to the open pit without extending the footprint.
The total mineral waste inventory generated by Rössing Uranium over the past 41 years now consists of 1.38 billion tonnes. The mineral waste facilities cover a total area of 1.377 ha north-west of the Khan River. This reﬂects no change from 2016 as the storage facilities only gained in height but not in footprint. These facilities are about the same size as the town of Swakopmund, but are being managed in such a way that they are not visible to the nearby Arandis community, nor from the B2 highway.
Non-mineral waste materials include, for example, waste water, scrap materials, used oils and lubricants from maintenance activities, as well as substantial amounts of packaging materials such as containers and wooden pallets. The aim of managing waste at the mine is to ensure that the waste generated onsite is reused, recycled, recovered and disposed of in accordance with Rio Tinto standards, applicable laws, regulations and permit conditions.
The same waste management contractor that was appointed in June 2016 continued to handle recyclable materials such as scrap metal and packaging materials (including containers, paper and wooden pallets) onsite.
During 2017 in total of 1,747 tonnes of recyclable waste (mainly scrap metal and domestic waste) were removed offsite by the contractor.
These recyclable materials are sorted further by the contractor at the Swakopmund facility and dispatched to Windhoek for recycling and reuse at the contractor’s refuse derived fuel plant. The nonrecyclable materials are disposed of at the landfll site of the Municipality of Swakopmund.
The contaminated waste generated on the mine includes all waste from the Processing Plant area. In 2017 1,018 tonnes of contaminated solid wastes were disposed of on the TSF, while 34 tonnes of oil sludge soil was disposed at the bioremediation facility for treatment.
Hazardous waste generated onsite includes oils, greases, redundant chemicals and other items such as ﬂuorescent tubes and batteries. A total of 62 tonnes of used oil were sent offsite for recycling. No hazardous waste materials were disposed of offsite during 2017.
In total 204 tonnes of hazardous wastes, including contaminated hydrocarbons and redundant chemicals, are temporarily retained onsite. This arrangement is necessary due to the Rio Tinto performance standard that requires an offsite waste facility that handles our waste to be licenced. We are currently in collaboration with a few external HSE partners for possible future waste management projects.
Energy effciency and greenhouse gas emissions
Rio Tinto strives to reduce greenhouse gas (GHG) emissions and improve energy effciencies. This is done through measuring and managing energy intensity and emissions.
Sources of GHG emissions at Rössing Uranium include electricity and fuel consumption, the transportation of reagents and uranium oxide, blasting explosives, waste management areas (the sewage plant and landfll site), and the extraction and processing of ore. The intensity of emissions is reported per unit of uranium oxide produced.
In 2017 the total energy consumption of the mine was 1.3 m GJ for 2,110 tonnes of uranium oxide drummed. This converts to an annual energy consumption of 616 GJ per tonne (GJ/t) of uranium oxide produced, which is 41 per cent above the projection target of 438 GJ per tonne uranium oxide produced.
This fgure represents lower energy consumption when compared with the rate of the previous two years (see Figure 20) and was due to the improved ore grade mined.
Emissions of carbon dioxide (CO2) per unit of production in 2017 amounted to 74.2 tonnes of CO2 equivalent per tonne (CO2- e/t) of uranium oxide, which is above the target of 52 tonnes CO2-e/t of uranium oxide for the year (see Figure 21).
The disturbance of land is an inevitable consequence of any mining activity. It is our objective to keep expansions of the footprints of the open pit, the rock disposal areas and the tailings facility to a minimum.
This is achieved by following a strategy of preventing area extensions and instead developing the facilities to higher heights, avoiding impacts on plant and animal life, as well as on archaeological fnds.
The total disturbed area calculated at the end of 2017 was 0.608 ha. The footprint of the TSF increased by 0.6 ha and about 0.09 ha service track contributed to the total land disturbed in 2017. To date our total foot print is 2,549.21 ha.
A view of the mine's open pit which currently measures 3 km long by 1.5 km wide, and is 390 metres deep.
Current mine plans foresee a cessation of production six years from now at the end of 2025.
The open pit will not be backflled; it will remain a mining void into the future. The Tailings Storage Facility will be covered with waste rock to prevent dust emissions and rainwater erosion. Rössing Uranium will continue recovering tailings seepage, but instead of reusing it for mining processes, it will be allowed to evaporate.
The Processing Plant and the mine’s infrastructure will be demolished. Recyclable materials will be decontaminated before selling them. Materials not leaving site will be disposed of safely and suffciently covered so that they cannot cause harm.
To achieve these objectives and targets, Rössing Uranium developed implementation plans for mitigatory measures and calculated the associated closure costs. A detailed closure plan at pre-feasibility level, containing more technical detail and higher cost-estimation accuracy than the current plan, will be developed in 2018 and 2019.
The establishment of the Rössing Environmental Rehabilitation Fund, which provides for expenditures associated with Rössing Uranium’s closure, complies with statutory obligations and stipulated requirements of both the Ministry of Mines and Energy and the Ministry of Environment and Tourism.
Accordingly, the fund agreement states that each year the mining company will make a contribution to the fund to provide for the eventual closure of the mine.
At the end of December 2017 the fund had a cash balance of N$718 million. In 2017 the total cost of closure, excluding retrenchment costs, was estimated at N$1.58 billion. The mine will make additional payments to the fund each year to provide for the eventual total cost of closure by 2025.
Invertebrates monitoring at Rössing Uranium
Rössing Uranium is committed to enhance biodiversity protection by assessing and considering ecological values and land-use aspects in investment, operational and closure activities.
One of the highlights of 2017 was the continuation of the invertebrate monitoring programme by means of a pitfall trapping method in the wider landscape. The focus was on the rocky hillside within our licence area that has not been sampled in the past.
The results indicated that 22 per cent of the species recorded in 2017 (48 out of 212) had not been found in the previous year and were first recorded on these sites in the reporting year. This shows that the increased sampling effort is being effective in recording the uncommon species.
In the past the invertebrate monitoring was carried out with the aim to collect information about the occurrence of 18 conservationimportant invertebrate species, with a particular focus on discovering the four spiders only found to date within the rocky hill habitat by Dr John Irish, a leading Namibian ecologist, during a survey at Rössing Uranium in 1984.
The results revealed that none of the species under investigation were found in the traps. However, the study also revealed that there was no change in invertebrate biodiversity since 1984.
Invertebrate is a term used for animals without backbones; the word refers to insects, spiders, scorpions, worms and snails, among others. Some invertebrates are generalists in habitat and thrive anywhere, while others are specialists occurring in limited habitats and sometimes even depend on a single plant species for their survival.
Invertebrates are the backbone of biodiversity, representing the majority of the world’s animal species and play a critical role in the functioning of the ecosystem.
Though they are usually small, their ecological importance is immense. If we lost invertebrates, ﬂowering plants would lose their pollinators, water would lose much of it fltration systems, the soil would lose its composters and earth turners, and the whole ecological system could collapse.
We monitor invertebrates to obtain and expand our knowledge about biodiversity in the Erongo Region. Monitoring of invertebrates improves our understanding of their abundance and diversity in the area we operate. This information can then be used to promote further research.
Monitoring reveals species of conservation value, enabling management strategies for these species to be developed. Monitoring information is vital in informing measures of landscape stability, ecosystem function and biodiversity.
Going forward, invertebrate monitoring will continue to focus on historically active, though now dormant areas to see how the natural environment re-established itself over long periods of time.
Rössing Uranium is committed to enhance biodiversity protection by assessing and considering ecological values and land-use aspects in investment, operational and closure activities.
One of the highlights of 2017 was the continuation of the invertebratemonitoring programme by means of a pitfall trapping method in the wider landscape. The focus was in the rocky hillside within our licence area that has not been sampled in the past.