Rössing Uranium aims to be a leader in environmental stewardship and to maintain its reputation as a responsible corporate citizen. This aim can be realised by understanding and appreciating our natural resources, and using them in a manner that will have created a positive impact after mining operations are completed.
As a resource-intensive industry, Rössing Uranium's operations impact on natural resources and the environment. We therefore continuously observe our performance in order to improve environmental management.
Key programmes include those on:
- water and tailings management (water demand and quality control, tailings stability);
- air quality control (dust, blasting noise and vibrations, environmental noise);
- waste management (of both mineral and non-mineral waste); and
- land-use management (including biodiversity, rehabilitation and closure planning).
Performances against our objectives and plans are discussed below.
Rössing Uranium's water management is one of the most significant environmental and operational aspects of our activities. Most of the mine's water management takes place at the Tailings Storage Facility and water recycling and reuse are the foundation of the mine's water saving programme.
AT A GLANCE:
- Water is reused in the Processing Plant. With the aid of frequent flow meter readings taken at various areas, an overview of the water balance is maintained at any given time.
- Our operating plan made provision for a target use of 2.3 million cubic metres (m³) of fresh water; the actual consumption of fresh water amounted to 2.1 million m³.
- Monitoring showed that ground vibration and blasting noise stayed within the limits of 12.5 mm/s and 134 dB respectively throughout the year.
- An erosion protection and sediment retention structure was completed in Dome Gorge, a tributary to the Khan River. This will prevent sediment from the rock dump deposited close to the Khan to reach the river.
- A social and environmental impact assessment was completed which assessed the feasibility of establishing a Rössing Uraniumowned desalination plant at the Mile 4 salt works.
Since the mine is located in the Namib Desert, water management is one of the most significant environmental and operational aspects of our activities.
It entails all aspects of water abstraction, dewatering, transport, storage and usage (potable and process), and involves surface water (including run-off), impounded water and groundwater.
Guiding our Water management plan is a formal Water strategy developed according to Rio Tinto's performance standards and guidelines. The aim of the plan is to ensure efficient, safe and sustainable use and protection of water resources and ecosystems.
A cornerstone of the mine's water and seepage management is its comprehensive monitoring programme, which starts at the Tailings Storage Facility (TSF).
The programme is designed to achieve three main objectives:
- ensure sufficient capacity at deposition areas;
- ensure low water levels in the tailings pools; and
- ensure proper functioning of all seepage control systems.
Water is reused in the Processing Plant. With the aid of frequent flow meter readings taken at various areas, an overview of the water balance is maintained at any given time. 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 on-site Sewerage Plant. These purified effluents are used in the open pit for dust control purposes.
We recognise that the TSF's structural integrity is a critical risk component that needs to be looked after on a continuous basis.
The stability of the TSF forms the cornerstone of the safe operation of our entire asset and the fact that it continued to increase in height prompted us to embark on two major stability reinforcement projects.
These projects include the construction of starter embankments on the north-to- north-eastern part of the TSF, as well as the buttress on the western side.
The construction work started in October 2014 and was completed successfully in October 2015, as per plan. Both projects were necessary not only with regard to extending the life of the TSF, but also to ensure its fundamental stability.
Following a review of the Tailings deposition plan, it was decided to construct a starter embankment on the north-to-north eastern side of the Tailings Storage Facility and a buttress on the western side, with the work completed towards the end of 2015. These two stability reinforcement projects will ultimately enable us to deposit tailings in an area on the facility that was previously not suitable for tailings deposition.
For further monitoring of the stability of the TSF, we embarked on a Piezometer installation project to monitor the stability at different areas of the TSF and to enable remediation in case of exceedances, which is highly unlikely. The project is due to be completed by mid-May 2016.
Surface water from pools forming at tailings deposition areas is recycled and reused on a continuous basis in the Processing Plant, minimising evaporation and infiltration into the tailings pile.
Remaining water that has infiltrated 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 recovery 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-filled 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.
To ensure that all systems are functional and zero discharge to the Khan River is maintained, water level measurements are taken on a network of more than 100 monitoring points.
A number of these points are also sampled to determine the quality of the groundwater, including the concentration of uranium and other radionuclides.
As a condition of the permit issued by the Ministry of Agriculture, Water and Forestry's Department of Water Affairs and Forestry, monitoring results are submitted to the department at regular intervals for review.
The position of the seepage plume around the TSF did not change during 2015. The map on the right shows the plume. Results of sampling carried out towards the end of 2015 are not available yet.
Our operating plan for 2015 made provision for a target use of 2.3 million cubic metres (m³) of fresh water and the actual consumption of fresh water amounted to 2.1 million m³. Unlike the previous reporting year, the freshwater use for 2015 was therefore lower than anticipated.
This was mainly due to the reduction in total tonnes of ore milled in the plant, as well as changes in the operating model. Lower tonnages at fixed water usage, combined with lower grades, result in a higher consumption of fresh water per tonne of U3O8 , as shown in the graph below.
Sustainable management of fresh water remains a key challenge for us, with issues relating to periodic supply interruptions from the bulk water supplier, interruptions in the functioning of pumping systems, unavailability of parts, and a lack of adequate storage capacity for the water in circulation.
In view of the above, various campaigns were implemented among our employees and contractors to heighten awareness about reducing demand and using supply responsibly during the year.
During the reporting year we therefore continued our internal Water Bucket awareness campaign published in our in-house newsletter, the e -Rössing Bulletin , to flag important issues to all water users. Other activities, such as the reed elimination project, continued as an effort to reduce water loss through evapotranspiration by reeds.
We were prompted to look into other water conservation alternatives when promising water reduction test work carried out at the tailings pumping system was unsuccessful.
These other alternatives included the TSFs Dewatering system project and the Water extraction project, aimed at maximising the recovery of groundwater stored in the tailings pile. These projects included the installation of replacement boreholes in the facility's dewatering system and in its water extraction bore fields, and were implemented and completed in 2015, with active monitoring ongoing. Both these projects are expected to yield much- needed low-quality water, which will in turn result in a significant replacement of freshwater consumption in the Processing Plant.
The reporting year saw the Mechanical seals project materialise whereby seals were installed on the slurry pumps at the slimes station in an effort to reduce freshwater consumption within the Processing Plant.
We also undertook the Storage lake cleaning project, which aims at increasing our storage capacity for poor-quality water to be used in the Processing Plant.
During early 2015, the social and environmental impact assessment (SEIA) for the construction and management of a desalination plant to supply the mine's water needs, was completed.
The assessment report and environ- mental management plan were submitted to the Ministry of Environment and Tourism for review and a decision on whether or not we can implement the proposed desalination project from a social and environmental perspective.
Unfortunately, an environmental clearance certificate was not issued by the Ministry. An appeal was lodged against that decision. The case was not heard by the end of 2015.
Khan River water use and quality
Rössing Uranium resumed its abstraction of saline groundwater from the Khan aquifer after the good rainy season in August 2011 to suppress dust in the open pit.
Such abstraction continued until June 2014, when the permit issued by the Department of Water Affairs and Forestry expired.
A new permit valid for two years until 25 March 2017 was received in April 2015 and an average of 115 m 3 of saline water per day was abstracted during 2015. This is 5 per cent of the permitted abstraction and 19 per cent of the aquifer's sustainable yield.
We continue to monitor the vegetation and water levels in the Khan River to prevent over-abstraction.
In accordance with the conditions of the abstraction permit, annual reports derived from the monitoring programme are sent to the Ministry of Agriculture, Water and Forestry's Department of Water Affairs and Forestry.
Air-quality management in mining is a complex task, mainly due to the wide range of source types, the fact that most are diffused and highly variable in nature, difficult to measure, and site-specific in terms of silt and moisture contents.
Our mining and milling activities create emissions to air. Dust is generated during blasting, loading and tipping of ore and waste, as well as during crushing and conveying of ore.
Winds at speeds above 30 km/h have the potential to erode fine particles from rock dumps and the TSF and disperse them into the wider environment.
Noise and ground vibrations are created during blasting that takes place about once a week, while the machinery deployed in the open pit and the Processing Plant generates environmental noise continuously.
n order to ensure that the controls for all the above emissions are functional, an environmental monitoring network was established around the mine site (see map below).
Monitoring the meteorological conditions at the same time allows drawing conclusions about the effectiveness of our controls.
The map shows the approximate position of the seepage plume around the Tailings Storage Facility.
Dust is measured in particulate matter (PM) ranging in diameter from 10 to 50 micro- metres. Activities such as mining, crushing and driving of heavy vehicles on unpaved roads are the principal emitters of dust at the mine.
PM10 is the measure of particles in the atmosphere with a diameter of less than or equal to a nominal 10 micrometres. These particles can be inhaled without being filtered out by the body and therefore can reach the lungs.
We monitor PM10 dust levels on site and at the nearby town of Arandis with continuous dust monitors (see the blue dots on the map above).
The levels recorded in Arandis for 2015 showed that dust concentrations were substantially lower than the World Health Organisation standard of 0.075 mg/m 3 , as indicated in the graph on the next page, with an average of 0.01 mg/m 3 for the year.
Three more continuous PM10 dust monitors are located at the mine: one at the mine boundary towards the west; and one to the east and one to the west of the TSF.
It was confirmed during the year that higher dust levels are associated with higher wind speeds, independent of whether a mine-related dust source is located upwind or not.
Total dust fall-out is measured at six stations at the mine boundary (see the single red dots away from the TSF on the map).
We adopted the residential dust fall-out limit published in South Africa by the National Dust Control Regulations (NDCR) on 1 November 2013. The fall-out limit is 600 mg/m 2 per day with an annual average target of 300 mg/m 2 per day.
Values measured during 2015 at the six stations ranged between 7 and 43 mg/ m 2 per day with an annual average of 18 mg/m 2 per day (see graph on this page: Dustfall-deposition rates, January- December 2015).
A dust monitoring programme is underway to quantify the emission of total suspended dust from the TSF during east wind events.
This is attempted by measuring dust movement along a section of 17 dust samplers along the western edge of the facility. In addition, a 1.3 km-long transect of dust fallout samplers determines how much of this dust is deposited downwind from the tailings area to the south west (see yellow dots on the map).
It was estimated that during 2015 a total of 26 tonnes of dust was moved across the line of the 17 dust samplers shown on the map.
From the measuring results obtained at the 1.3 km-long transect it is estimated that only 20 per cent reached the wider environment and were deposited up to 900 m away from the TSF towards the south west (see red dots on the map).
A total of 80 per cent of the mobilised dust falls out in the first 200 m downwind of the line of the 17 dust samplers. Fall- out rates measured in the 900 m-strip were all well below the residential dust fall target of 300 mg/m 2 -day.
Noise and vibration from blasting
We monitor environmental noise in order to minimise it to threshold levels and to identify events when such levels are exceeded. When we started with the development of the Phase 2 portion of the open pit a number of years ago, initially blasting took place at the surface areas.
Blasting noise was audible over greater distances from the open pit and concerns were raised by the public that blasting vibration could affect infrastructure away from the mine. In order to monitor the effect of blasting on the mine and in Arandis, vibration monitoring is being carried out continuously.
During 2015, monitoring showed that ground vibration and air-blast stayed within the limits of 12.5 mm/s and 134 dB respectively throughout the year (see graph above) and no concerns were raised by the public.
Noise generated by the routine operations of the mine is compared to the 45 dB(A) daytime limit for rural districts in accordance with the South African National Standards code of practice, SANS 10103:2008. Noise levels measured stayed within the limits throughout 2015 (see graph above).
Rio Tinto regards efforts to stabilise global atmospheric concentrations of greenhouse gases (GHGs) at lower levels as a priority. In keeping with this, we measure and manage our emissions.
At the mine, sources of GHG emissions include electricity and fuel consumption, the transportation of reagents and of uranium, blasting (explosives), waste manage ment areas (Sewerage Plant and landfill site), and the extraction and processing of ore. The intensity of emissions is reported per unit of uranium oxide produced.
In 2015, the total energy consumption of the mine was 1,777,420 GJ. This converts to an annual energy consumption of 714 GJ per tonne (GJ/t) of uranium oxide produced, which is 276 GJ/t of uranium oxide produced above the target of 438 GJ/t.
Thus, due to lower grade and a lower throughput of ore, the target was exceeded in 2015.
Emissions of carbon dioxide (CO 2 ) per unit of production in 2015 amounted to 85.87 tonnes of CO 2 equivalent per tonne (CO 2 - e/t) of uranium oxide (U 3 O 8 ), which is below the projection of 90 tonnes CO 2 -e/t of U 3 O 8 for the year.
Substantially curtailed production since 2014 resulted in our energy consumption and GHG emissions per unit of production being higher than projected in 2008.
New projections have been set for the years 2016 to 2020, taking the new production scenarios into account.
During 2015 a total of 19.3 million tonnes of mineral waste were generated by the mine. This includes 12.5 million tonnes of waste rock and 6.8 million tonnes of tailings.
The reduction from 23.0 million tonnes generated in 2014 is due to the curtailment of production linked to uranium market forces. A similar tonnage of waste generation is projected for 2016.
The total cumulative mineral waste stored on-site at the end of December 2015 amounted to 408.9 million tonnes of tailings and 923.4 million tonnes of waste rock.
Mineral waste facilities cover a total area of 1,372 ha north-west of the Khan River. This reflects no change from 2014 and the storage facilities only gained in height but not in footprint.
An erosion protection and sediment retention structure was completed in Dome Gorge, a tributary to the Khan River. This will prevent sediment from the rock dump deposited close to the Khan to reach the river.
In addition to mineral waste consisting of waste rock and tailings, domestic, industrial and hydrocarbon waste produced at the mine has to be managed as well. A contract with a recycling contractor came to an end in September 2015.
A new contract is being negotiated, extending the scope to an integrated waste management approach including waste reduction, reuse, recycle, and various disposal alternatives. The waste management operations will become fully operational in the first half of 2016.
Recycling of waste generated at the mine continued during 2015. In total, 455 tonnes of recyclable waste (mainly scrap metal) were removed by the waste management contractor.
Of the recyclable materials generated during 2015, 201 tonnes are still stored on site. These materials include paper, plastic containers, batteries, redundant tyres and conveyor belts. A total of 159 tonnes of used oils were sent off site for recycling.
The mine's landfill site received 124 tonnes of domestic and light industrial waste.
Uncontaminated hazardous waste generated on the mine includes oils and greases, and other items such as fluorescent tubes and batteries. In total, 48 tonnes of hazardous waste were disposed of at the Walvis Bay hazardous waste site. We store 110 tonnes of oil sludge in the bioremediation facility on the TSF, while 21 tonnes of radioactively contami nated hydrocarbons are stored on site. We disposed of 695 tonnes of hazardous waste in the hazardous waste site on the TSF.
An erosion protection and sediment retention structure was completed
in Dome Gorge, a tributary to the Khan River. This will prevent
sediment from the rock dump deposited close to the Khan to reach the river.
Changes in total land use
As mining progresses, the SJ Pit gets deeper every year, while the rock dump area and TSF gain in height.
We decided to extend these mineral waste storage facilities in height rather than increasing their footprint. Although this measure results in conserving undisturbed land, it increases the visual impact that mining has on the surroundings. The TSF, for example, has become more visible from the B2 main road as its height increased in the last few years.
The total area covered by the mine's activities at the end of 2015 was 2,544 ha. By conforming to the policy of maintaining the smallest footprint possible, we achieved minimal change in total land disturbed in 2015. The footprint area increased by 0.2 ha this year compared with 2.8 ha in 2014.
During 2015 the emphasis of biodiversity management was changed from assessing the impact of potential future developments in currently undisturbed areas to investigating ways to successfully rehabilitate areas already impacted. This is an important development, since restoration in the desert environment is a very slow process and careful monitoring needs to start early to assess its success.
Reviewing the results of monitoring invertebrates (insects without backbones) over a five year period, showed that biodiversity index values for current sampling sites display the same broad trends today as they did in 1983.
This is heartening because it suggests that, despite the permanent habitat destruction in the core mining area, in general effects seem to be limited by distance. Most of the surrounding areas do not show any catastrophic changes to invertebrate biodiversity in the past 30 years.
Going forward, invertebrate and flora biodiversity in historically active but now dormant areas will be monitored to see how the natural environment has re-established itself over longer periods.
Currently, we are studying the effect of tailings dust dispersion on the ecology to the southwest of the TSF. Initial results indicate that dispersion does not have any obvious large scale effect on invertebrates or other fauna in the area.
We expected that increased dust deposition would have negatively affected biological soil crust, by reducing the translucency of the rocks under which it forms and the sunlight it needs for photosynthesis.
However, the initial results of the assess- ment do not show any clear trends across the study area that can be attributed to dust deposition. Fensteralgen (or 'window lichen', a type of lichen that grows in parts of the Namib Desert) are common and abundant both inside and outside the study area and both near to and far from the TSF. The flora assessment is still ongoing while laboratory data are awaited.
In addition, during the reporting year, we developed rehabilitation success criteria and discussed it with stakeholders.
During 2016 work will start to rehabilitate old sand mining pits used during the construction of the mine nearly 40 years ago. Learnings from the exercise will be incorporated into the mine's rehabilitation and closure plans.
Current life-of-mine plans foresee cessation of production at the end of 2025.
Principally, we will not backfill the open pit with rock: it will remain a mining void in the future. On the other hand, we will cover the TSF with waste rock to prevent dust emissions and stormwater erosion. We will continue recovering tailings seepage, but instead of reusing it for mining processes, it will be allowed to evaporate.
We will also break down the Processing Plant and the mine's infrastructure, and decontaminate it before selling it or disposing of it safely.
To achieve these objectives and targets, we have developed implementation plans for mitigatory measures and calculated the necessary closure costs. A major technical and cost update of the plan will again take place in 2016.
The establishment of the Rössing Environmental Rehabilitation Fund, which provides for the mine's closure expenditure, complies with statutory obligations and stipulated requirements of both the Ministry of Mines and Energy and the Ministry of Environment and Tourism.
Accordingly, clause 15.2 of the Fund Agreement states that "The mining company shall before the end of its financial year concerned, pay to the Fund a contribution towards the estimated cost of implementing the measures so approved".
At the end of December 2015, the fund had a cash balance of N$505 million. The total cost of closure excluding retrench ment costs is estimated at N$1.4 billion. The mine will make additional payments to the fund each year to provide for the eventual total cost of closure by 2025.
Tailings cover test section
During the previous reporting year, we planned to construct a cover test section of the TSF in mid-2015 in order to test the practicality of the cover's design and its effectiveness.
However, due to ore production being below plan during this reporting year, to use the crusher for a campaign to only crush waste rock was not feasible. No suitable cover material was therefore available and the test cover could not be constructed.
This case study illustrates how specialist studies have influenced management decisions, changed development plans and consequently protected the environment.
A social and environmental impact assessment was completed during 2015 which assessed the feasibility of establishing a Rössing Uranium-owned desalination plant at the Mile 4 salt works. One of the critical environmental issues identified early in the scoping phase of the project was the location of the desalination plant close to the Mile 4 oyster pond.
Although a literature search and local sources indicated that Damara Terns had been recorded and had bred regularly at this site, more detailed and updated information was required on the distribution, numbers and breeding success at this site to make a final decision on the location of the proposed desalination plant. The original layout had the desalination plant positioned centrally within this core breeding area.
Although the footprint of the plant is much smaller than the breeding site, any form of intrusive disturbance during the breeding season, when the birds are present from October to April, could result in reduced breeding success or in the Damara Terns abandoning this breeding site, probably permanently.
It was discussed early on whether the plant needed to be relocated out of the core Damara Tern breeding area. However, the exact extent of the area was not known and it was decided to observe breeding behaviour before a final decision on the location of the plant was to be taken.
Due to the potential sensitivity of the site as identified during the scoping study phase, the bird specialists initiated regular monitoring visits three times per week from 15 September 2014 onwards. The purpose was to establish when the birds arrived and the activities they engaged in, and to verify whether, when and where they would take up sites. The terns arrived on 8 to 11 October 2014 and the study was completed on 28 April 2015.
The detailed study showed that the Mile 4 breeding site and surrounding areas were used by at least 32 adult Damara Terns during the peak of the season, whereas up to 52 adults were recorded at the roost site. At least seven chicks were recorded, with nine fledglings at the roost site in March 2015. The study confirmed that the categorisation of the breeding area as 'sensitive' in terms of the environmental impact assessment was justified, given that at least 15 nest sites were occupied over the studied season.
It also showed that the area designated as a buffer area was equally important as a nursery area for rearing chicks before they fledged. These findings indicated that the area as a whole is important for around 2 per cent of the global Damara Tern population, and thus of conservation significance.
A decision was taken to shift the desalination plant away from the sensitive site and an alternative site was identified. The alternative location was taken forward in the assessment report submitted for approval by the Environmental Commissioner of the Ministry of Environment and Tourism.
(Photographs: The two photographs of Damara Tern parent with chick, and of chick were supplied by Justine Braby; the photograph of Damara Tern in flight was supplied by Gunnar Petterson.)
Damara terns (Sterna balaenarum) are very small, fast-flying terns endemic to the Namib Desert coastline.
This species is listed as 'Near Threatened' owing to its moderately small population.