Using our natural resources
in a sustainable manner
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 sustainable manner that will have created a positive impact after closure.
Up to one quarter of the global population of Lithops ruschiorum (stone plant), which is endemic to Namibia, can be found at the mine. The densest of these populations on the mine is behind the Tailings Storage Facility, so it is crucial to avoid impacting them.
As a resource-intensive industry, Rössing Uranium's operations impact on natural resources and the environment. We therefore continuously improve our Environmental Management Plan to minimise negative impacts and maximise benefits. Key programmes include those on:
- water (demand, and quality control);
- air quality control (including the emission of dust, blast noise and vibrations);
- energy efficiency and greenhouse gas emissions;
- waste management (of both mineral and non-mineral waste); and
- land use management (including biodiversity, rehabilitation and closure).
The various environmental management programmes in place at the mine are discussed over the next few pages.
Since the mine is located in the arid part of the Namib Desert, water management is one of the most significant environmental and operational aspects of our activities. It is an integral part of our HSE Management system and entails all aspects of water abstraction, dewatering, transport, storage, usage (potable and process), and direct/indirect discharge, which 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 standard on water use and quality control, and supported by Rio Tinto's water use and quality control guidance notes. The aim of the standard 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.
On the side in the plant where water is reused, frequent flow meter readings are taken at various areas to maintain an overview of the water balance at any time.
Water recycling and reuse are the foundation of the mine's Water Savings Programme. 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 Sewage Plant. These effluents are used in the open pit for dust control purposes
Most of the mine's water management takes place at the TSF. We recognise that the facility'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, namely the construction of the starter embankments on the north-to-north-eastern part of the TSF, as well as the buttress on the western side of the facility. These are both necessary projects, not only with regard to extending the life of the TSF, but also to ensure its fundamental stability. Both projects are short-term, with expected completion dates set for September 2015.
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 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-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 Department of Water Affairs, monitoring results are submitted to the Department at regular intervals for review.
Our operating plan for 2014 made provision for a target use of 3 million cubic metres (m3) of fresh water. The 2014 plan was initially based on operations conducted 24/7, but, due to their curtailment, a five-day operating plan was introduced, with a new target of 2.3 million m3. Actual consumption of fresh water during 2014 amounted to 2.4 million m3.
As in the previous reporting year, the water performance for 2014 was worse 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 unit consumption, as shown for the years 2011 to 2014 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 sustainably during the year. We therefore continued our internal Water Bucket awareness campaign published in the mine's in-house newsletter, the e-Rössing Bulletin, to flag important issues to all water users.
Other activities, such as the reed elimination project, came into effect in an effort to reduce water loss through evapotranspiration by reeds. Another was the recommissioning of the solar-powered boreholes project located in the Upper Panner Gorge area, where there is no electricity supply from the national grid.
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 TSF Dewatering System Project and the TSF Water Extraction Project, aimed at maximising the recovery of groundwater from the TSF. These projects included the installation of replacement boreholes in the TSF Dewatering System and TSF Water Extraction bore fields, and were implemented and completed in 2014, with active monitoring still 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.
Other projects which commenced in 2014 and are expected to yield results in 2015 include the Mechanical Seals Project, where seals are installed on the slurry pumps at the slimes station in an effort to reduce freshwater consumption within the Processing Plant, and the Storage Lake Cleaning Project, which aims at increasing our storage capacity for poor-quality water to be used in the Processing Plant. Another example is the Pumping Systems Upgrade Project.
During the reporting year, we also conducted a social and environmental impact assessment (SEIA) for the construction and management of a desalination plant to supply the mine's water needs. The report was made public in December 2014 and included studies done by environmental specialists.
We will review the SEIA and a related Social and Environmental Management Plan after we have solicited and received comment from the public. We then submit these documents and the feedback on them to the Ministry of Environment and Tourism for review and eventual decision on whether or not we can implement the proposed desalination project from a social and environmental perspective.
Khan River water use and quality
Rössing Uranium resumed its abstraction of saline groundwater from the Khan aquifer in August 2011 to suppress dust in the open pit. Such abstraction continued until June 2014, when our permit expired. We expect a new permit to be issued soon
The mine allows for a daily abstraction of up to 800 m3. This is lower than the permitted 2,383 m3/day, and lower than the aquifer's sustainable yield. We continue to monitor the vegetation and water levels in the Khan and Swakop Rivers to prevent over-abstraction. In accordance with the conditions of our abstraction permit we send annual reports derived from our monitoring programme to the Ministry of Agriculture, Water and Rural Development's Department of Water Affairs.
The current Air Quality Management plan guides the way we manage environmental dust at the mine. We document all air quality standards applied at the mine and keep an inventory of all air emissions.
Environmental dust: PM10 results and new stations
Dust is measured in particulate matter (PM) ranging in diameter from 10 to 50 micrometres. Activities such as mining and crushing are the principal emitters of dust at Rössing Uranium. PM10 is the measure of particles in the atmosphere with a diameter of less than or equal to a nominal 10 micrometres.
Rössing Uranium measures dust emissions to ensure not only that exposure levels do not exceed prescribed occupational limits, but also that existing and newly introduced controls efficiently detect differentiation as a result of process changes.
Because of public concern, we continuously monitor PM10 dust levels at the nearby town of Arandis. The emissions recorded for 2014 showed that dust levels were much lower than the standard of 0.12 mg/m3, as indicated in the graph alongside, with average emissions at 0.011 mg/m3 for the year.
Two more PM10 dust samplers are located at the mine: one at the mine boundary towards the west, and one to the east of the TSF. They are relocated as needed to help us understand the dust emission intensity in various areas at the mine.
A Dust Monitoring Programme is also under way to quantify the emission of total suspended dust from the TSF during east wind events. This is achieved by measuring dust movement along a section of 17 samplers along the western edge of the facility. A 2-km-long transect of dust fallout samplers determines how much of this dust is deposited downwind from the tailings area to the west. Late 2014 saw the completion of sampling for the year's east wind season; data will be reported on in the next review period.
Noise and vibration from blasting
We monitor environmental noise to minimise it to threshold levels and to identify events when such levels are exceeded. The information gleaned is necessary for assessing Rössing Uranium's compliance with various standards and for addressing public concerns about excess noise or blast vibration. Our Geotechnical Section also utilises the feedback to investigate the impact of blast vibration on the stability of the pit.
During 2014, blast noise and vibration stayed in compliance with the set standards and no concerns were raised by the public.
Noise generated by the routine operations of the mine is compared to the 45 dBA daytime limit for rural districts in accordance with the South African National Standards code of practice, SANS 10103:2008. Higher noise levels in March and November 2014 measured at the communication centre outside the mine (Station 01) were caused by vehicles driving past the monitoring station during monitoring. This does not require any corrective action.
Environmental Adviser, Inekela Iiyambo, inspecting instruments to monitor air blast and ground vibration. We monitor air blast and ground vibration as a result of our blasting activities to minimise it to threshold levels and to identify events when such levels are exceeded. The information gleaned is necessary for assessing Rössing Uranium's compliance with various standards and for addressing public concerns about excess noise or blast vibration. Our Geotechnical Section also utilises the feedback to investigate the impact of blast vibration on the stability of the pit.
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 management areas (Sewage Plant and landfill site), and the extraction and processing of ore. The intensity of emissions is reported per unit of uranium oxide produced.
In 2014 the total energy consumption of the mine was 1,108,877.4 GJ. This converts to an annual energy consumption of 721.93 GJ per tonne (GJ/t) of uranium oxide produced, which is 63.72 per cent above the target of 454.12 GJ/t set in 2008. Due to lower grade and a lower throughput of ore, the target was exceeded in 2014.
Emissions of carbon dioxide (CO2) per unit of production in 2014 amounted to 82.00 tonnes of CO2 equivalent per tonne (CO2-e/t) of uranium oxide (U3O8), which is above the target of 56.65 tonnes CO2-e/t of U3O8 for the year.
Substantially curtailed production resulted in Rössing Uranium's energy consumption and GHG emissions per unit of production being higher than the five-year targets originally set.
During 2014 a total of 23 million tonnes of mineral waste were generated by the mine. This includes 16 million tonnes of waste rock and 7 million tonnes of tailings. The significant reduction from 37 million tonnes generated in 2013 is due to the curtailment of production linked to uranium market forces. The total cumulative mineral waste stored on-site at the end of December 2014 amounted to 402 million tonnes of tailings and 911 million tonnes of waste rock. Mineral waste facilities cover a total area of 1,372 ha north-west of the Khan River. A similar tonnage of waste generation is projected for 2015.
Our Tailings Storage Facility undergoes an inspection at least once a year. Consultants from SLR Environmental Consulting (Pty) Ltd, SRK and Aquaterra do an annual inspection and make recommendations for improvement. In keeping with Rio Tinto requirements, SLR Environmental Consulting also conducts an inspection of the Tailings Dam as a major waste storage facility.
Recycling of waste at the mine continued during 2014. In total, 481 tonnes of waste (mainly scrap metal) were removed by the waste management contractor employed by Rössing Uranium. Of the recyclable materials generated during 2014, 59 tonnes are still stored on-site. These materials include paper, plastic containers and batteries. A total of 26 tonnes of oils were sent off for recycling. The mine's landfill site received 342 tonnes of domestic and light industrial waste.
Hazardous waste generated on the mine includes radioactively contaminated materials, oils and greases, and other items such as fluorescent tubes and batteries. In total, 23 tonnes of hazardous waste were disposed of at the Walvis Bay hazardous waste site, 42 tonnes of oil sludge are being stored in the bioremediation facility on the tailings dam, 67 tonnes of radioactively contaminated hydrocarbons are still stored on-site, and 291 tonnes of hazardous waste were disposed of in the hazardous waste site on the Tailings Storage Facility.
Changes in total land use
As mining progresses, the SJ open pit gets deeper every year, while the Rock Dumps area and Tailings Storage Facility (TSF) gain in height. A decision was made to extend these mineral waste storage facilities in height rather than increasing their footprint areas. Although this results in conserving undisturbed land, it increases the visual impact mining has on the land. The TSF, for example, has become more visible from the B2 main road as its height increases.
The total area covered by the mine's activities at the end of 2014 was 2,544 ha. By conforming to the policy of maintaining the smallest footprint possible, the mine has ensured minimal annual increases in total land disturbed. In 2014, the footprint area increased by 0.1 per cent (2.8 ha), compared with 4.3 ha in 2013.
From the biodiversity knowledge base built up over the nearly four decades of the mine's life, it became clear that we needed a better understanding of the bigger picture in which our mining operations were set, that is, the entire landscape, particularly the ecological connections, patterns, processes and services provided within it.
A programme of monitoring of invertebrates found in the wider landscape further away from the mine continued during 2014. After three years of monitoring, we now have a sizable data set which a Namibian invertebrate specialist will review and interpret in early 2015. We expect that a number of species previously classified as critically endangered (due to single finds in the 1984 ecological survey) can now be reclassified to a lower category of vulnerability, and their geographical range of existence determined.
Impact avoidance is a preferred alternative to impact mitigation and subsequent rehabilitation. We therefore exercised impact avoidance in preparing new tailings deposition areas on the north-western side of the TSF. Since we decided to discontinue the development of a heap leach plant on top of this facility in 2013, the earmarked area had become available for further tailings deposition
Construction of tailings embankment walls started during 2014. We carried out the embankment designs in such a way that we could avoid ground disturbance at the nearby populations of the stone plant, Lithops ruschiorum. Up to one quarter of the global population of lithops, which are endemic to Namibia, can be found at Rössing Uranium. The densest of these populations on the mine are behind the TSF, so it is crucial to avoid impacting them.
Current life-of-mine plans foresee cessation of production at the end of 2024. 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 pumping tailings seepage, but instead of reusing it for mining processes, it will be allowed to evaporate. Rössing Uranium 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 update of the plan will 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. Thus, 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 2014, the Fund had a cash balance of N$415.1 million. The mine will make additional payments to the Fund each year to provide for the eventual total cost of closure by 2024.
Closure Project Implementation Plan
Development of the first of three parts of a Closure Project Implementation Plan began in December 2014. The outcome of the exercise will provide a schedule of activities between 2015 and 2024 to allow prioritised and focused closure planning work in a currently financially constrained environment.
Tailings cover test section
A test section of the tailings cover is planned to be constructed for mid-2015 in order to test the practicality of the cover's design and its effectiveness. Discussions with the Mining Department took place in order to arrange stockpiling of crushed waste rock at the TSF during the 2015 mid-year shutdown. A contractor to be appointed in early 2015 will do the cover placement.
The stability of the Tailings Storage Facility (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. The construction of the starter embankments on the north-to-north-eastern part of the TSF can be seen in the top photo. The construction of a buttress on the western side of the facility can be seen in the bottom photo. These are both necessary projects, not only with regard to extending the life of the TSF, but also to ensure its fundamental stability. Both projects are short-term, with expected completion dates set for September 2015