Mines Need Integrated Approach to Water Risks

Securing community and government support will require careful management of water resources.

SRK Consulting

2-BLOGMining projects will find it increasingly difficult to secure community and government support if they fail to manage impacts on surface water and groundwater – not only during the life of the mine but in the post-closure phase.

This warning from SRK Consulting (SA) partner and principal hydrologist Peter Shepherd comes as African countries follow global trends in clamping down ever more strictly on water pollution from a range of sources. Mining is the second largest industrial user of water, using between seven and nine billion cubic metres each year – the equivalent of the combined water usage of Nigeria and Malaysia.

“All over the world, water is becoming the focus of attention, and Africa is no different,” said Shepherd, who has worked extensively on mine water projects on the continent. “As the demand for fresh water rises, communities and farmers are doing what they can to secure adequate allocations. This involves much greater activism regarding allocations and pollution of water resources, which is having an increasing impact on mine water supply and usage.”

As with other aspects of exploration and mine development, public participation is becoming a key principle of integrated water management – and is now frequently a legislated part of the compliance process. Indeed, such public participation is increasingly recognized as vital to business sustainability generally, and not limited just to the arena of compliance. Much of SRK’s work in the mineral sector relates to a strategic approach to stakeholder engagement as a building block for sound community relations.

According to a recent report by industry analysts Frost & Sullivan, mining has become one of the most dynamic markets for water and wastewater treatment. The report predicts that by 2016 the industry’s demand for water-treatment equipment and services could be worth $3.6 billion.

Shepherd said it was undeniable that mining could adversely affect water quantity and quality, and posed a significant risk to Africa’s water resources. Consumers in this day and age require more awareness of environmental and sustainability issues from mining companies, before accepting their products.

”Mining operations can substantially alter the hydrological and topographical characteristics of the mining areas, affecting the surface runoff, soil moisture, evapo-transpiration and groundwater behaviour,” he said.

“The possible extent and complexity of mining’s impacts makes it vital to adopt an integrated approach to mine water management, indeed, many countries’ regulations now demanded such an approach as shortages of clean water are experienced and the true cost of water becomes apparent.”

Integrated water management includes resource-directed measures, which aim to protect and manage the receiving environment, and source- directed measures, which aim to control the impacts at source through pollution prevention, water reuse and water treatment mechanisms. “Disregard for integrated water management issues in mining development will ultimately lead to unsustainability in the sector, as damage to water resources is arguably the worst environmental consequence of mining,” said SRK (SA) partner and principal civil engineer Kurt Uderstadt.

The costs of managing water for mining purposes, such as pumping and treatment costs, can also continue beyond the life of the mine if not properly planned and implemented, said Uderstadt – creating unforeseen and potentially unmanageable financial risks. “Planned management of key items such as potable and non-potable water supply, groundwater supply, surface drainage and groundwater ingress can reduce a mine’s developmental costs, improve regulatory compliance, avoid litigation and provide sustainable mine closure,” he said. “Often, minor changes in the mine development plan result in large improvements in integrated water management.”

An integrated strategy must take into account the various catchment management strategies and other initiatives that are in place on a macro scale such as the reconciliation studies that have been prepared for the various catchments within the country, said Shepherd.

Based on the principle of integrated mine water management, regulations may also require that attention be paid to ‘cumulative impacts’ in the planning and developing of a mine, said Shepherd. “Each of the elements of a mining operation needs to be considered for its potential impact – such as the shafts or pits, the waste dumps, the tailings disposal facilities, metallurgical plants, haul road and residential areas,” he said. “But the law also requires that the mine assess the cumulative impact of all these factors together.”

In addition, in a country like South Africa, where authorities demand an integrated approach to water management, regional impacts need to be investigated before a mine can be considered compliant. The regional aspect emerges because mines are often geographically concentrated, especially when extracting from the same orebody. “This invariably leads to hydrological interconnections between neighbouring mines, affecting surface water and groundwater,” said Shepherd. “The result is that each mine’s activities will have consequences for the others, so these regional interactions need to be defined in every mine’s water management plan.”

“There is also an emphasis on the use of suitably qualified persons,” said Shepherd. “Many of the aspects of integrated water management require hydrological, geohydrological and geochemical modeling or specialized technical design work.” According to Shepherd, the most important aspects for mines to address in terms of best practice guidelines for water management were the prevention of pollution, the minimisation of impacts, and the management of the discharge of wastewater. “Minimising impacts involves using as little of the local water resources as possible, re-using and reclaiming what you do use, and treating water wherever necessary,” said Shepherd.

He emphasised the importance of planning from the earliest stages of a project, to reduce risk and costs later in the life-of-mine. “Pollution prevention strategies can be effectively planned, developed and implemented in the exploration, operational and closure phases of the mining operation,” he said. “This reduces the management and financial burden associated with remediation during the operational and especially closure phases.”

“Climate change will also affect mine water management, as changing rainfall patterns will make certain areas drier and others wetter,” said SRK associate partner and principal scientist Manda Hinsch. “This will impact on the operations of slimes dams and other pollution control strategies, and calls for more attention to be paid to disaster management.”

The sector has made considerable progress in recent decades in addressing many of the water challenges encountered on mine sites, among which have been advances in water saving strategies through thickened tailings. “The advantages of thickened tailings have been numerous,” Shepherd said. “There is reduced water reticulation, a smaller pool on top of the tailings storage facility, and less danger of infiltration or seepage; there is also potential for co-disposal of tailings and waste rock.” He said that general ‘housekeeping’ and operating practices have also improved, steadily raising the bar for water management standards over recent decades.

“When working with clients, we recommend and help implement a range of solutions that supports both compliance and longer term sustainability,” said Shepherd. “For instance, it is important for mines to avoid cross-contamination of materials and chemicals by keeping the work area clean and organized. They need to segregate their waste streams based on each stream’s level of contamination, which means careful consideration of piping and storage facilities.

“Proper safeguards need to be installed – such as bunded areas, diversion berms and concrete paving – alongside the implementation of better cleanup practices like washing and sweeping. We encourage clients to consider the general layout of the site and process plant, as well as the placement of their facilities. Finally, it is vital they have a good understanding of the plant and water circuits.”

Protection of groundwater resources is a particular concern in water-scarce environments, as any impact by mining could negatively affect other users. Specific requirements apply to the management or rehabilitation of groundwater, according to Shepherd.

“It is important firstly to understand the geological, geochemical and hydrogeological environment,” he said. “Once the source has been conceptualized, then the potential risks to human health and the environment can be identified, followed by the assessment of an appropriate management strategy. In cases where contamination may have occurred, we need to understand the history and pollutants before any rehabilitation options can be considered.”

Shepherd listed some of the most important aspects considered in the sector to address mine water management.

• impact prediction
• stormwater management
• waste and sewage treatment
• water and salt balances
• water monitoring systems
• management measures
• water management for mine closure

Some of the main impacts to be predicted and avoided would be dewatering, mine inflows and contamination, he said.

“The problem of dewatering can occur when mining activity leads to groundwater resources drying up, affecting springs, boreholes and baseflow to rivers,” said Shepherd. “Mine inflows take place when groundwater flows into mine workings, causing slope instability and other problems with mining. Contamination is essentially any reduction in the quality of groundwater, and can be caused by various mining and related activities.”

He cautioned the mining sector not to be complacent about its water management strategies, especially as this vital resource becomes more scarce and costly. “Remember that public sentiment will always trump mining companies when it comes to competition for water, even if the mining companies are compliant with the letter of the law,” said Shepherd.

South Africa’s National Water Act describes Integrated Water Resource Management (IWRM) as comprising all aspects of the water resource, including water quality, water quantity and the aquatic ecosystem quality. The IWRM approach provides for both resource-directed and source-directed measures.

This article was written as part of the research conducted by GBR for its Mining in Africa Country Investment Guide (MACIG) 2015, which was published in February 2015 and can be viewed here. To participate with your comments, please contact Sharon Saylor at ssaylor@gbreports.com.

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