Waste and Hazardous Materials Management

Mining and processing gold produces waste by-products in the form of tailings and waste rock, 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. We strictly enforce the design and operational requirements of our tailings facilities, regarding their location, water management, maintenance, operation and monitoring.

In some cases, tailings are used as backfill in underground and open pit projects. The Marlin mine, for example, used filtered tailings to backfill one of the two open pits. We do not dispose of any tailings in riverine systems or marine environments.

Waste rock management is a key environmental aspect of our operations. Depending on the characteristics of the waste rock, appropriate waste rock and tailings management procedures are developed as required by our Sustainability Excellence Management System (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 moved to waste rock dumps on the surface. 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 the mine’s life, the waste rock dumps are re-contoured and re-vegetated to provide long-term stabilization of the material.

Our SEMS recognizes the important environmental aspects of mine materials management and includes specific standards to address them. We recognize tailings management as a significant concern shared by us and our stakeholders. 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.

In 2014, we developed a tailings stewardship program to ensure good practices in construction, operation, maintenance, monitoring and, ultimately, closure of our tailings storage facilities. The strategy addresses stakeholder concerns and assures stakeholders that tailings facilities are well-managed, providing secure storage, reduced costs and impacts, improved operational excellence and consistent monitoring. Implementation began in 2015.

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 regularly examined/tested via third party;
  • 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 and Tailings

The quantities of waste rock and tailings generated are shown in the table below.

2015 2016 2017

Waste rock handled [t (metric)]

163,208,022

144,421,732

145,086,845

Tailings generated [t (metric)]

48,467,660

42,689,418

44,386,630

Waste by Type and Disposal Method

Responsible storage, handling and disposal of solid and hazardous waste are central components of sound environmental management. At our operations, our practices are based on minimizing the generation of wastes and residues, reusing and recycling wastes or by-products, and, when materials cannot be recycled, disposing of them in an acceptable manner.

Our most significant non-hazardous waste streams include scrap metal, used tires, used oil, used antifreeze, inert industrial garbage and organic waste. All 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.

Waste hydrocarbons (when not reused), on-site, and glycol/antifreeze are removed 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.

2015 2016 2017

Scrap steel

30,400

18,400

20,339

Tires

5,300

3,800

3,323

Waste hydrocarbons

2,790

2,740

2,981

Waste glycol/antifreeze

110

130

65

Inert industrial garbage

7,250

13,730

3,737

Organic waste

4,600

3,800

1,145

Batteries

120

110

85.5

Laboratory waste

780

660

600

Mercury occurs naturally in some ore deposits and is typically recovered as elemental mercury, along with the targeted metals. Peñasquito was the only mine generating mercury during ore processing in 2017. The amount generated was 83.3 kilograms and as of the end of the year there were 135.7 kilograms stored on site. Elemental mercury at Peñasquito is collected in United Nations approved shipping containers, which are stored within the locked, secured area of the processing facility. This process is in accordance with local requirements and with our Sustainability Excellence Management System (SEMS) standard for mercury management.

Spills

All spills reported are tracked, investigated and analyzed to identify root causes. We then implement actions to mitigate any consequences and to prevent recurrences. Spill incidents are classified in ascending order of severity, from Category I to Category V based on their actual and potential impacts. Incidents of Category III and above are reported to the corporate level. There were 15 spills in 2017 that were Category III or above.

Spill category Number % of total Estimated Volume Spilled [m3]

Hydrocarbon spill

8

53

15 m3

Cyanide-related spill1

2

13

161 m3

Other material spill2

5

34

11 m3

Total

15

100

187 m3

All spills were responded to immediately and did not result in any significant environmental impacts or financial reporting liabilities. Additionally, all our sites are certified under the International Cyanide Management Code which provides direction for the appropriate management of cyanide-related spills.