Waste and Hazardous Materials Management
Mining and processing gold produces waste by-products in the form of tailings, waste rock, sludge as well as some hazardous and non-hazardous materials.
Tailings are the by-product of minerals processing. They are finely crushed and ground rock particles from which the valuable mineral portion has been extracted. We use retention dams and raised embankments to store and manage tailings. Specific design and operational requirements regarding the location, water management, maintenance, controls and monitoring of these dams and embankments are strictly enforced. We close and maintain these facilities at the end of the mine life. Tailings can also be used in certain cases as part of underground and open pit backfill projects. Marlin is backfilling a portion of one of the two open pits with tailings that have been managed to meet the appropriate criteria, including filtering to reduce the moisture content. We also use tailings to backfill certain areas of underground workings, where appropriate. We do not dispose of any tailings in riverine systems or marine environments.
Waste rock is a key environmental aspect at our operations, as are tailings at those sites with milling facilities. Our sites analyze the characteristics of these materials, and based on the results, waste rock and tailings management procedures are developed at all of our sites as required by the SEMS. Most of the waste rock produced in our underground mines is returned underground to fill mining voids. In open pit mines, the waste rock is transferred to waste rock dumps. In some limited cases, we are able to sequence mining in different pits or pit sections to allow for some use of waste rock as pit backfill. At the end of mine life, the waste rock dumps are re-contoured and revegetated to provide stable, long-term containment of the material.
Sludge produced at our operations is typically from water treatment plants. This material is usually disposed of in our tailings dams, although final disposal depends on the environmental characteristics of the sludge.
Our SEMS recognizes the important environmental aspects of waste rock and tailings management, and includes specific SEMS standards to manage them. Additionally, we developed a Tailings Stewardship Strategy in 2014 and implementation began in 2015. This is a management strategy developed to ensure best practices are implemented for proper construction, operation, maintenance, monitoring and, ultimately, closure of our tailings storage facilities. We designed our strategy to provide assurances that tailings facilities are managed using best practices – providing secure storage, reduced costs and impacts, improved operational excellence and consistent monitoring – and to address stakeholder concerns.
We are committed to managing tailings in a manner that effectively mitigates environmental, public health and safety, and community impacts while maximizing the long-term security of the tailings facilities and sustainable land use options.
The primary objectives of our Tailings Stewardship Strategy are to minimize risk and manage liabilities; improve sustainability; improve comprehensive technical and operating standards; ensure best practices for cost reduction and operational efficiency; perform inspections and reviews by qualified third parties; and ensure design, operation, training, risk management and closure planning are performed.
We recognize tailings management as a significant issue shared by us and stakeholders. Tailings stewardship ensures planning, design, construction, operation and closure of our tailings storage and water retention facilities will be carried out in a manner such that:
- Structures are physically stable under all anticipated conditions;
- Solids and water are managed within designated areas;
- Facilities meet or exceed regulatory or standard engineering guidelines;
- Facilities are chemically stable so that the quality of any seepage or surface runoff does not endanger human health or the environment; and
- Facilities can be closed in a manner that is compatible with the surrounding land use and that will have a manageable impact on the environment.
Waste Rock, Tailings and Sludge
The quantities of waste rock, tailings and sludge generated are shown in the table below.
Waste Rock, Tailings and Sludge
|Waste rock (Mt)||207.1||189.5||169.4|
Waste by Type and Disposal Methods
Responsible storage, handling and disposal of solid and hazardous waste are central components of sound environmental management. Waste management practices must be based on the principles of minimizing the generation of all wastes and residues, the recycling and reuse of wastes or by-products, and the disposal in an acceptable manner of any materials that cannot be recycled.
Our most significant non-hazardous waste streams include scrap metal, used tires, used oil, used antifreeze, inert industrial garbage and organic waste. All of our scrap metal and some tires are recycled. Many of our operations have implemented recycling programs for materials such as paper, pallets, glass and aluminum, and some of our sites have implemented composting programs for organic wastes.
At some operations, and where it is permitted by regulation, we dispose of large tires in a controlled manner within our waste rock dumps. Our waste classified as hazardous waste includes batteries and assay lab waste.
Waste hydrocarbons, when not reused on-site, and glycol/antifreeze are removed from our sites by licensed waste disposal or recycling operators for reuse, recycling or incineration. Where permitted, we reuse waste hydrocarbons on-site as a substitute for fuel oil in the ammonium nitrate and fuel oil (ANFO) blasting program.
The table below includes the waste generation figures for these waste streams.
|Material (in tonnes)||2015||2014||2013|
|Inert industrial garbage||7,250||3,950||3,990|
Mercury occurs naturally in some ore deposits and, in those cases, it is typically recovered along with the targeted metals. Mercury then requires specific management to avoid health and environmental impacts. Our operations generated 24.47 kilograms of mercury in 2015, which all occurred at the Peñasquito mine. All of the mercury collected during 2015 was stored on-site at Peñasquito.
All spills reported are tracked, investigated and analyzed to identify root causes. We then implement actions to prevent recurrences and to mitigate the consequences of future incidents. We classify all incidents into five categories in ascending order of severity from Category I to Category V. Incidents are assessed based on their actual and potential impact. Incidents in Category III and above are reported to the corporate level and thus are classified at Goldcorp as “reportable incidents”. We reported a total of 22 reportable spills in 2015, compared to 31 in 2014. The estimated volume spilled is also shown in the table below – in most cases, the majority of the volume spilled is recovered.
|Spill category||Number||% of total||Estimated volume spilled|
|Other material spill||16||73||2,600m3|
All our sites were certified under the Cyanide Management Code, which provides direction for the appropriate management of cyanide-related spills. All spills were responded to immediately and did not result in any significant environmental impacts or financial liabilities.