Skip booklet index and go to page content

Environmental Code of Practice for Metal Mines

Summary

S.1 Context

The Environmental Code of Practice for Metal Mines is designed to support the Metal Mining Effluent Regulations(MMER) under the Fisheries Act and includes other subjects that are not dealt with in the MMER that may have an influence on the environmental impact of mining operations. The text of the MMER is available online.

The starting point for the development of the Code of Practice is the final report (1996) of the multi-stakeholder Assessment of the Aquatic Effects of Mining in Canada (AQUAMIN). AQUAMIN was initiated in 1993 to evaluate the effectiveness of the Metal Mining Liquid Effluent Regulations (MMLER). This process included consideration of the Environmental Code of Practice for Mines that was published in conjunction with the MMLER in 1977.

It is important to note that while this code is intended to apply specifically to metal mines, the recommendations in the document may be helpful to all sectors of the mining industry.

S.2 Code Objective, Scope and Implementation

The objective of the Code is to identify and promote recommended best practices in order to facilitate and encourage continual improvement in the environmental performance of mining facilities throughout the mine life cycle, in Canada and elsewhere. The document is intended to be a resource for mine owners and operators and regulatory agencies, as well as the general public, particularly those who live in communities potentially affected by mining activities.

The Code addresses all phases of the mining life cycle from exploration and feasibility studies through planning and construction, operation, and closure, and it covers a broad spectrum of environmental aspects ranging from air, water and waste management to biodiversity conservation.

The Code was developed by Environment Canada in consultation with a broad range of stakeholders.

The Code of Practice will be adopted by Environment Canada and others as a guidance document that recommends environmental protection practices for metal mines.

Recommendations in the Code do not carry regulatory status, and a commitment by companies to implement the recommendations in the Code does not remove obligations for such companies to comply with all applicable municipal, Aboriginal, provincial, territorial, and federal legal requirements.

S.3 Mining Life Cycle Activities and Environmental Concerns

The mine life cycle typically includes the following phases: exploration and feasibility, planning and construction, operations, and closure. Activities associated with the mine life cycle may include:

  • line cutting, drilling, trenching and bulk sampling;
  • development of mine workings and construction of associated infrastructure;
  • extraction of ore;
  • management of mine and site drainage;
  • ore processing;
  • disposal of waste rock, tailings and other wastes; and
  • site reclamation activities.

Potential environmental concerns associated with mining include:

  • wastewater from site runoff, mining and ore processing, and mine wastes;
  • releases of airborne particulate matter and air emissions from engine operations and other processes;
  • effects on terrestrial ecosystems, including wildlife;
  • effects on aquatic ecosystems, including fish;
  • effects on local and regional surface water and groundwater flow;
  • noise;
  • planned and accidental releases of pollutants;
  • aesthetic impacts, such as alteration of landscapes; and
  • social impacts, such as impacts on sport or subsistence fisheries.

S.4 Recommended Environmental Protection Practices

To reduce or eliminate the potential negative environmental impacts associated with mining activities, the environmental practices summarized in Tables S.1, S.2, S.3, S.4 and S.5 are recommended.

Table S.1: Recommendations for Environmental Management Tools
NumberSubjectSummary of Recommendations: Environmental Management Tools
R 101Environmental Policy Statement

Each company owning or operating a metal mine or engaged in exploration activities should develop and implement a corporate environmental policy statement that includes commitments to:

  • continually improve environmental protection measures and practices;
  • focus on pollution prevention, where feasible, rather than treatment;
  • comply with relevant environmental legislation and regulations and other requirements, such as industry association policies and best management practices to which the metal mine subscribes;
  • maintain the environmental policy, communicate it to all employees, and communicate relevant components of the policy to on-site contractors; and
  • make the environmental policy available to the public.
R 102Environmental AssessmentMine proponents or current owners/operators should consult with federal and provincial/territorial regulatory and environmental assessment agencies early in the planning process to determine whether a proposed project will require an environmental assessment. Environmental assessment principles should be followed by companies proposing new or significantly modified or expanded facilities. Proponents may consult the Canadian Environmental Assessment Act Reference Guide: Determining Whether a Project is Likely to Cause Significant Adverse Environmental Effects or relevant provincial/territorial documents.
R 103Environmental Assessment – Baseline StudiesWater quality, aquatic ecosystems, air quality, soil quality, terrestrial ecosystems, groundwater and other environmental data collected as part of pre-operational baseline studies associated with environmental impact assessments should be collected so that it is comparable with monitoring data collected later in the mine life cycle. Data should be collected and analyzed so that it will be possible to identify long-term trends, periodic change and fluctuations in rates of change.
R 104Environmental Risk Management

Site-specific environmental risk management procedures should be developed and implemented in a manner consistent with guidance provided in:

  • CAN/CSA-Q634-M91 - Risk Analysis Requirements and Guidelines; and
  • CAN/CSA-Z763-96 - Introduction to Environmental Risk Assessment Studies.
R 105Environmental Management Systems

Site-specific environmental management systems (EMS) should be developed, implemented, maintained and updated in a manner that is consistent with a nationally recognized standard or system such as ISO14001, developed by the International Organization for Standardization (ISO). Environmental management systems should be used to manage all environmental aspects of the activities and operations over which an operation has control or which it can reasonably influence. Elements of an EMS should include:

  • a clear definition of objectives and targets to meet the company's environmental policy;
  • accountability for environmental action across the company;
  • stated procedures to translate the environmental policy into day-to-day practices;
  • monitoring, checking and auditing of the system; and
  • implementation of actions to provide continual improvement.
R 106Pollution Prevention PlansSite-specific pollution prevention plans should be developed, implemented and updated in a manner consistent with the guidance provided in the Environment Canada (2001) Guidelines for the Implementation of the Pollution Prevention Planning Provisions of Part 4 of the Canadian Environmental Protection Act, 1999(CEPA 1999).
R 107Environmental Management Plans

Site-specific environmental management plans should be developed, implemented and updated throughout the mine life cycle. The plans should include, as a minimum, descriptions of the following:

  • information about the owner/operator of the mine and information about the mine itself, including a description of the mining and ore processing methods used and the geographic setting of the site;
  • the company's environmental policy statement;
  • environmental performance requirements;
  • air quality management programs;
  • water quality management programs;
  • management programs for tailings and waste rock;
  • land management programs;
  • pollution prevention planning;
  • management of garbage and other waste materials;
  • environmental objectives and targets along with schedules for achieving objectives and targets;
  • environmental management programs and auditing;
  • relationships with stakeholders, including local communities;
  • procedures for communicating with regulatory agencies and stakeholders; and
  • periodic review of the environmental management plan for effectiveness and continual improvement.
R 108Environmental Performance IndicatorsEnvironmental performance indicators should be developed to facilitate tracking of the mining facility's overall environmental performance through readily understood measures of the facility's environmental performance and effects.
R 109Monitoring and Inspection of Environmental Management Facilities

Site-specific plans for the monitoring and inspection of on-site environmental facilities and infrastructure should be developed, implemented and updated. Plans should include:

  • documentation of procedures for the monitoring and inspection of each on- site environmental facility, including air emission control equipment; water management and wastewater treatment facilities; transportation, handling, storage, and containment facilities for chemicals; waste handling and disposal facilities; and air quality and water quality monitoring and control instrumentation;
  • a documented schedule for monitoring and inspections, including timing of monitoring and inspections and methods to be used;
  • identification of those responsible for monitoring and inspections and for following up on the results of inspections;
  • documentation of procedures for reporting the results of monitoring and inspection to both internal management and regulatory agencies;
  • documentation of procedures for following up on monitoring and inspection reports;
  • procedures for periodically reviewing and updating the monitoring and inspection plans; and
  • procedures for quality assurance and quality control (QA/QC).
R 110Environmental Monitoring

Environmental monitoring should include:

  • monitoring of environmental releases, such as releases to air, water and land; and
  • monitoring of environmental performance indicators, including air and water quality and aquatic and terrestrial species and ecosystems.

Site-specific environmental monitoring plans should be developed, implemented and updated throughout the mine life cycle that describe:

  • all environmental monitoring and reporting required under regulations and permits;
  • all environmental monitoring and reporting to be conducted which is beyond that required under regulations and permits;
  • applicable environmental standards and environmental quality objectives, such as water or air quality standards or objectives;
  • schedules for monitoring;
  • sampling procedures, sample preservation requirements, and analytical methods employed;
  • procedures for the comparison of monitoring results with applicable environmental standards and environmental quality objectives;
  • actions to be undertaken when requirements set out in regulations or permits have not been met;
  • procedures for reporting the results of monitoring to company management, regulatory agencies and the public;
  • procedures for following up on monitoring reports;
  • procedures for periodically reviewing and updating the environmental monitoring plans; and
  • procedures for quality assurance and quality control (QA/QC).
R 111Environmental MonitoringEnvironmental monitoring should include specific plans to measure and verify all effects and endpoints that were predicted in the environmental assessment.
R 112Cumulative Effects Monitoring

Environmental monitoring plans should include measures to assess possible cumulative effects. The assessment of cumulative effects associated with mine development and operation should begin as early as possible in the mine life cycle, with consideration given to:

  • applicable legislation related to the assessment of cumulative effects;
  • potential activities in the vicinity of the mining facility, including infrastructure, that may contribute to cumulative effects; and
  • existing monitoring activities, including any existing activities related to the assessment of cumulative effects.
R 113Cumulative Effects MonitoringWhen environmental monitoring activities identify an effect or a change not predicted or not deemed acceptable in the environmental assessment, additional monitoring measures should be implemented to investigate the cause of the effect.
R 114Traditional Ecological Knowledge

Environmental assessment and monitoring should include, to the extent possible, a consideration of traditional ecological knowledge, and this knowledge should also be considered in relevant aspects of environmental planning and management. In gathering and incorporating traditional ecological knowledge into environmental management, mine owners/operators should:

  • respect the ownership, source and origins of the knowledge and the needs and sensitivities of its holders, and obtain their approval to use or disseminate that knowledge;
  • establish trusting relationships with those who hold traditional ecological knowledge;
  • work on projects of common interest and benefit;
  • foster good communication between partners; and
  • provide value-added knowledge back to the community in the form of useful products (such as reports) and services.
R 115Emergency PlanningSite-specific environmental emergency plans should be developed and implemented, then tested and updated on a regular basis. These plans must respect legislated requirements, such as those under the Environmental Emergency Regulations and the Metal Mining Effluent Regulations. In this regard, the plan should be consistent with the Implementation Guidelines for Part 8 of the Canadian Environmental Protection Act, 1999 - Environmental Emergency Plans from Environment Canada.

However, the scope of environmental emergency plans should be broad and comprehensive in nature, and should go beyond the legislated requirements, particularly with respect to hazard identification, risk analysis and consequence as well as community involvement and communications. As such, the elements of emergency planning should also be consistent with recognized guidance documents such as APELLfor Mining: Guidance for the Mining Industry in Raising Awareness and Preparedness for Emergencies at Local Level (United Nations Environment Programme, 2001).
R 116Environmental Training and Awareness

Site-specific procedures should be developed and implemented to identify environmental training needs and ensure that all personnel receive environmental training. As such, the procedures should encompass:

  1. general awareness training for employees and service providers, including contractors, where the training includes but is not limited to:
    • the organization's environmental program, including the environmental policy and relevant environmental practices;
    • regulatory obligations; and
    • environmental emergencies procedures, including spill prevention, reporting, response and evacuation procedures;
  2. an environmental training program that includes:
    • a list of all personnel that require environmental training and a categorization of groups of personnel with regards to the nature of the specific environmental training required; and
    • an outline of the environmental training required for each group of personnel, the training methods to be used, and the required frequency of refresher training; and
  3. the identification of requisite competencies of contractors and environmental auditors.
R 117Closure Planning – Designing for ClosureThe development of closure plans should begin during the planning phase for proposed mines and as early as possible in the mine life cycle for existing mines. Closure plans should be considered and incorporated into all aspects of mine planning, construction and operation so that key aspects of the closure are planned for throughout the mine life cycle. Plans should identify measures to be undertaken during the operations phase that are aimed at progressive reclamation of disturbed or developed areas of the mine site.
R 118Closure Planning – Designing for Closure

Mine closure should be carried out in a way that prevents or minimizes impacts and risks to the environment and human health after closure. Closure plans should identify site-specific objectives for mine closure and the intended post-closure land use for the site. Closure plans should detail the processes that will be used to decommission and reclaim all aspects of the mining facility, including:

  • mining and ore processing facilities;
  • site infrastructure; and
  • water and waste management facilities, including waste rock piles and tailings management facilities.
R 119Review of Closure Plans

Closure plans should be reviewed and revised as necessary throughout the mine life cycle. The plans may become more detailed, incorporating to a greater degree all activities related to the mine and taking into greater consideration site conditions and monitoring results. Closure plans may also be revised in response to:

  • the results of progressive reclamation activities;
  • the results of tests to assess specific aspects of the closure plan;
  • public response to a proposed closure plan;
  • changes in mine operations, such as production rate or ore type;
  • changes in technology, such as improvement in technology for preventing or controlling acidic drainage;
  • changes in economic conditions, such as input costs and other economics related to mine closure; and
  • unexpected or adverse conditions encountered during the construction and operations phases of the mine life cycle.
R 120Environmental AuditingPeriodic environmental audits should be conducted to determine (a) whether the site is operating in compliance with applicable regulatory requirements and appropriate non-regulatory and corporate requirements and (b) whether the EMS and other environmental plans have been properly implemented and maintained.

The recommendations in the Code of Practice should be included in the audit criteria, and each audit should take into consideration the results of previous environmental audits. Environmental auditors should be qualified by virtue of their relevant experience and training, and audit team members should be objectively selected.

ISO19011, Guidelines for Quality and Environmental Management Systems Auditing, should be considered in the development and implementation of the audit program.
R 121Public Involvement

Site-specific public involvement plans should be developed, implemented and updated throughout the mine life cycle. These plans should describe mechanisms by which public input will be sought and addressed. These plans should also:

  • include a list of key community contacts;
  • describe proposed mechanisms for informing the public that information is available and for distributing and receiving information; and
  • describe measures to be used to provide information in a form that is understandable to the public; and
  • include plans for public reporting of monitoring activities.
R 122Product Stewardship

Product stewardship programs should be developed and implemented, with the objective of minimizing the environmental impacts associated with the products used and produced by the mine. The programs should include consideration of:

  • types of materials used;
  • sources of supply of materials;
  • sources and types of energy used;
  • type and amount of packaging;
  • management of manufacturing by-products and wastes;
  • recycling or reuse of containers or the return of containers to the manufacturer;
  • possible exchanges of waste materials with other local industries, such as the use of pulp mill waste as tailings cover material; and
  • local purchase of supplies to support community businesses and residents.
R 123Adaptive Management

Mine owners/operators should use adaptive management methods to revise and refine the environmental management strategy. Adaptive management should consider a wide range of factors, including:

  • the results of environmental audits or other evaluation activities;
  • the results of environmental monitoring;
  • the results of monitoring of the performance or condition of environmental infrastructure, such as containment structures, water management systems or treatment facilities;
  • technological developments; and
  • changing environmental conditions.


Table S.2: Environmental Management Practices for the Exploration and Feasibility Phase
NumberSubjectSummary of Recommendations: Environmental Management Practices for the Exploration and Feasibility Phase
R 201Exploration and FeasibilityEnvironmental management plans should cover the full range of activities related to exploration, including land acquisition, surveys, access, camp and associated facilities, stripping, trenching, drilling and sampling. Environmental management practices should address water management and water quality, waste management, land disturbance, air quality, reclamation and closure.

The recommended practices identified in Table 4.1 should be followed during the exploration and feasibility phase. In addition, practices recommended for the planning, construction and mine operations phases apply during exploration and feasibility, albeit on a smaller scale.
R 202Exploration and FeasibilityThe guidelines of the Environmental Excellence in Exploration (e3) program developed by the Prospectors and Developers Association of Canada should be considered in the design and implementation of environmental management plans during the exploration and feasibility phase.
R 203Inclusion of Environmental Costs in Feasibility StudiesThe anticipated costs of environmental management during mine operations, as well as the costs of mine closure and long-term post-closure liabilities, should be considered in the economic feasibility study for the mine and should be appropriately accounted for in the financial planning of the mine owner and operator.
R 204Reclamation and Closure of Exploration Project

When exploration activities have ceased and further development of the site is not planned by the proponents:

  • water intakes, culverts, docks and other waterway structures, as well as all machinery, equipment and building structures, should be removed;
  • waste dumps, sewage/washwater pits and drill holes should be properly capped; and
  • all areas that have been disturbed should be revegetated or rehabilitated to allow for natural revegetation.


Table S.3: Environmental Management Practices for the Planning and Construction Phase
NumberSubjectSummary of Recommendations: Environmental Management Practices for the Planning and Construction Phase
R 301Water Management Planning

Site-specific surface water management plans should be developed and implemented. The plans should include:

  • the identification of the mine property subwatersheds, including those for mine waste areas, drainage flow paths, and receiving water bodies;
  • estimates of flow rates for each subwatershed under normal climatic conditions and extreme precipitation (i.e., design storm or low flow) events;
  • analysis of the local groundwater regime, including flow direction and rates, recharge and discharge areas, and relationship with the local surface water regime;
  • a water balance for the mine property that takes into account all significant water inputs, losses, and water recycling;
  • descriptions of seasonal variations in surface water flow (e.g., due to melting of snow pack) and impacts on flow of any existing water level control structures;
  • descriptions of measures to be implemented to manage water; and
  • the identification and assessment of opportunities for diverting natural runoff away from the mine site to prevent pollution of this water.
R 302Water Use and Recycling

Ore processing facilities should be designed to:

  • minimize the volume of fresh water that is used for ore processing by:
    • using ore processing methods that require less water; and
    • maximizing the recycling of water to reduce requirements for freshwater intake; and
  • avoid or minimize the use of reagents that require treatment prior to effluent discharge.
R 303Diversion of Clean Runoff and Consolidation of Wastewater Streams

In planning the site layout, consideration should be given to:

  • consolidating to the degree practicable all facilities that are potential sources of wastewater with similar characteristics and treatment requirements;
  • diverting all clean streams and drainage runoff away from areas of possible contamination by constructing ditches or dikes; and
  • locating effluent discharge points away from environmentally sensitive areas.
R 304Designing for Extreme Weather EventsSurface drainage facilities should be designed to handle peak conditions at least equivalent to a once in 100 year flood event. Consideration should be given to projections of increased extreme weather events resulting from global climate change, and facilities should be planned accordingly.
R 305Prediction of Wastewater Quality

Site-specific programs for the prediction of wastewater quality should be developed and implemented. This work should begin as early as possible in the mine life cycle and continue throughout the planning and construction and mine operations phases. Programs for the prediction of wastewater quality should include:

  • the identification and description of all geological materials (including rock as well as overburden) to be excavated, exposed or otherwise disturbed by mining;
  • the prediction of the metal leaching and acidic drainage potential of all geological materials, including the timing and conditions during which metal leaching and acidic drainage are expected to occur; and
  • the prediction of other potentially harmful components in mine wastewater, including processing reagents, ammonia, algae-promoting substances, thiosalts, chlorides and elevated pH.

These steps are further detailed in recommendations R 306, R 307 and R 308.

R 306Identification and Description of Geologic Materials

Site-specific programs for the identification and description of rock and other geological materials that will be or have been moved or exposed as a result of mining activity should include, for each material:

  • spatial distribution of the material, as well as the estimated mass of material present;
  • geological characterization of the material, including its mineral and chemical composition;
  • physical characterization of the material, including grain size, particle size and structural characteristics including fracturing, faulting and material strength;
  • hydraulic conductivity of the material; and
  • the degree of any oxidation of the material that has taken place.
R 307Prediction of Metal Leaching and Acidic Drainage Potential

All rock units and other geological materials that will be or have been moved or exposed as a result of mining activity should be tested for their metal leaching and acid generation potential. The testing program should be designed to meet site-specific needs, using a combination of static and kinetic test methods, as appropriate. The following documents should be consulted in designing, implementing and interpreting the results of the prediction program:

  • William A. Price (1997). Draft Guidelines and Recommended Methods for the Prediction of Metal Leaching and Acid Rock Drainage at Mine Sites in British Columbia. British Columbia Ministry of Employment and Investment;
  • MEND Manual, Volume 3 – Prediction (2000); and
  • Bill Price (2005). List of Potential Information Requirements in Metal Leaching/Acid Rock Drainage Assessment and Mitigation Work. MEND Report 5.10E.
R 308Prediction of Other Potentially Harmful Components in Mine Wastewater

The presence of other components in mine wastewater that are potentially harmful to the environment should be predicted, in particular:

  • the potential concentrations of ore processing reagents (e.g., cyanide) and their breakdown products in processing wastewater;
  • the potential concentration of ammonia in wastewater;
  • the potential pH of wastewater from ore processing, since processing is often carried out at a high pH; and
  • the potential for the occurrence of thiosalts in wastewater from ore processing.
R 309Waste Rock and Tailings Disposal PlanningThe results of site-specific programs for the prediction of water quality should be considered in the planning of waste rock and tailings disposal management practices. In particular, where there is a potential for metal leaching or acidic drainage, prevention and control of metal leaching and acidic drainage should be primary considerations in the design of waste rock piles, tailings management facilities, and associated water management facilities.
R 310Prevention and Control of Metal Leaching and Acidic Drainage from Waste Rock and Tailings

Demonstrated practices should be planned and implemented to prevent or control acid generation and/or metal leaching from waste rock piles and tailings management facilities, where the potential exists. These practices may include:

  • limiting the production of waste rock with acid generation or metal leaching potential;
  • preventing or limiting the availability of oxygen to the acid-generating material by:
    • disposing of potentially acid generating waste rock or tailings under a water cover; or
    • using composite covers with a saturated layer to limit infiltration of oxygen;
  • blending or layering potentially acid generating material with neutralizing materials;
  • segregating potentially acid generating or metal leaching material from other material to facilitate efficient management of this material and to reduce the volume of material that needs to be managed in a way that prevents or controls acid generation and metal leaching; and,
  • diverting surface water away from storage areas to minimize flushing and volumes of effluent.
R 311Prevention and Control of Metal Leaching and Acidic Drainage from Waste Rock and TailingsIn cases where freezing of waste rock or tailings in permafrost is to be used as a method to prevent or control acidic drainage, consideration should be given to the potential for a warmer climate to thaw the construction material in the future. An alternative method to prevent or control acidic drainage that does not depend on the use of frozen material should be developed if it is determined that there is a significant risk of future thawing.
R 312Selection of Locations for Waste Rock Piles and Tailings Management Facilities

The following factors should be considered in choosing the location for waste rock piles and tailings management facilities:

  • local and regional surface water and groundwater flow and potential surface water and groundwater contamination;
  • water management scheme and preliminary water balance;
  • permafrost conditions in northern areas;
  • topography;
  • sites of existing (open or closed) waste rock piles;
  • existing and possible future land and resource uses, including use of the receiving watershed and distance from habitation and areas of human activity;
  • baseline environmental conditions, including natural flora and fauna;
  • potential impacts on vegetation, wildlife, aquatic life and any downstream communities;
  • condition of basin and dam foundations;
  • deposition plane and storage volume/capacity;
  • preliminary design of containment and water management structures;
  • potential impact area;
  • potential releases of airborne particulate matter;
  • aesthetic considerations; and
  • mine closure considerations.

The rationale for the selection of the site should be clearly documented, including discussion of alternate sites that were considered and rejected.

R 313Tailings Management Facility Design

The following factors should be considered in the design of tailings management facilities:

  • physical and chemical characteristics of the tailings material, including metal leaching and acidic drainage potential, as well as the potential for liquefaction;
  • hydrology and hydrogeology, including local climatic conditions and extreme weather events (projections of increased extreme weather events as a result of global climate change should also be included);
  • foundation geology and geotechnical considerations, as well as seismic data and earthquake risk;
  • availability and characteristics of construction materials;
  • topography of the tailings management facility and adjacent areas; and
  • permafrost conditions in northern areas.
R 314Tailings Management Facility DesignIn designing tailings management facilities, the retention time for wastewater in the facilities should be maximized to allow for settling of suspended solids and the natural degradation of contaminants such as ammonia and cyanide.
R 315Design of Containment Structures for Tailings Management FacilitiesIn designing and constructing containment structures for tailings management facilities, such as dams, stringent engineering standards should be employed.
R 316Design of Containment Structures for Tailings Management FacilitiesThe long-term monitoring and inspection of containment structures for tailings management facilities should be considered during the design and construction phase. In particular, appropriate instrumentation should be installed during construction to facilitate monitoring during the mine operations and closure phases. Specific design allowances should be made for and consideration should be given to location-specific conditions, such as the presence of permafrost, slopes, seismic activity and site drainage requirements, particularly during peak flow conditions.
R 317Long-term Stability of Waste Rock PilesWaste rock piles should be designed to remain structurally stable throughout the mine life cycle and post closure. Local seismic stability data and the risk of earthquakes should be considered in the design of waste rock piles.
R 318Long-term Stability of Tailings Management FacilitiesTailings management facility risks should be assessed and managed in each phase of the life cycle to determine potential failure modes and probabilities and the consequences of failure. Measures should be planned to reduce these risks and to put in place contingency plans in the event of failure.
R 319Long-term Stability of Tailings Management FacilitiesTailings management facilities should be designed to remain structurally stable, as per the Dam Safety Guidelines of the Canadian Dam Association. Tailings management facilities should be designed to withstand a probable maximum flood (PMF) event. Further, containment structures should be designed to remain structurally stable in the event of a maximum credible earthquake (MCE).
R 320Planning and Construction of Wastewater Treatment Systems

Wastewater treatment systems should be planned taking into account:

  • the water management plan;
  • the results of prediction of wastewater quality;
  • the waste rock and tailings disposal plans;
  • relevant regulatory requirements for effluent quality; and
  • relevant environmental performance indicators, including any water quality objectives.
R 321Cyanide Management Planning

For mines that will use cyanide for the processing of gold or base metals ores, cyanide management should be planned in a manner consistent with practices described in the International Cyanide Management Code (International Cyanide Management Institute, 2008). In particular, cyanide management planning should take into consideration:

  • measures to minimize the amount of cyanide required, thereby reducing reagent use and limiting concentrations in tailings;
  • design and implementation of measures to manage seepage from cyanide facilities to protect surface water and groundwater;
  • design and operation of cyanide treatment systems to reduce cyanide concentrations in effluent discharged to the environment; and
  • design and implementation of spill prevention and containment measures for process tanks and pipelines.
R 322Cyanide Management PlanningIf natural degradation of cyanide is to be used as a treatment method for cyanide, the tailings management facility should be designed to ensure that the retention time of the liquid phase is adequate for natural degradation to occur during high flow conditions, e.g., during spring runoff.
R 323Management of Chemicals

The design processes for new metal mines and modifications to existing metal mines should include procedures to:

  • identify potential environmental concerns associated with proposed chemical processes and related environmental effects; and
  • assess the use of alternative processes and chemicals, when they are available, with a view to mitigating or eliminating environmental effects.
R 324Management of ChemicalsSite-specific chemical management procedures should be developed and implemented for the safe transportation, storage, handling, use and disposal of chemicals, fuels and lubricants. These procedures should include appropriate emergency preparedness planning.
R 325Management of Chemicals

Each mine owner/operator should evaluate, on an ongoing basis, opportunities to reduce the quantities of potentially harmful chemicals used in the operation of the mine. This evaluation should include consideration of:

  • selection of equipment and processes;
  • potential modifications to existing equipment;
  • new technologies, processes and procedures;
  • the substitution of different materials;
  • equipment maintenance; and
  • employee training programs.

Based on this evaluation, measures to reduce the use of potentially harmful chemicals should be implemented, as appropriate.

R 326Management of Chemicals

The chemical storage and containment facilities used at each mine should be designed and constructed to meet the appropriate standards, regulations and guidelines of pertinent regulatory agencies and the owner/operator's environmental policy, objectives and targets. As a minimum, chemical storage and containment facilities should:

  • be managed to minimize the potential for spills;
  • provide containment in the event of spillage and be managed to minimize opportunities for spillage;
  • comply with Workplace Hazardous Materials Information System (WHMIS) standards;
  • ensure that incompatible materials are stored in ways to prevent accidental contact and chemical reactions with other materials; and
  • minimize the probability that a spill could have a significant impact on the environment.
R 327Domestic Sewage and Wastewater DisposalWhere sewage or domestic wastewater is to be disposed of on site rather than sent to a municipal sewage treatment plant for disposal, an on-site sewage treatment facility should be constructed. The objective of these facilities is to prevent the contamination of surface water and groundwater, including drinking water supplies, and to meet all applicable regulatory standards.
R 328Domestic Sewage and Wastewater DisposalSludge from the treatment of sewage and domestic wastewater should be disposed of in an acceptable manner. Sludge may be disposed of on site or in a landfill, it may be used as cover material for tailings or waste rock, or it may be disposed of off site.
R 329Management of Kitchen and Food WastesWastes from on-site kitchen and dining facilities should be disposed of in a manner that does not attract wildlife. Measures should be put in place to ensure that all food wastes and food containers are properly disposed of, including those used away from kitchen and dining facilities. Training programs should be put in place to ensure that all employees and on-site contractors are aware of the importance of proper disposal of food wastes and the importance of not feeding wildlife on site.
R 330Avoidance of Environmentally Sensitive AreasAll mine facilities should be located and designed to avoid environmentally sensitive areas. The determination of environmentally sensitive areas should be undertaken in consultation with appropriate stakeholders, local Aboriginal communities and government officials.
R 331On-Site Roads and Access RoadsRoads should be routed to avoid water bodies and wildlife habitat, where possible, and should be designed to avoid sharp turns to minimize the risk of spills and accidents. Route placement should consider the final use of roads with respect to either enhancing or limiting continued access to wilderness and developed areas by the public following closure.
R 332On-Site Roads and Access Roads

Measures should be designed and implemented to prevent and control erosion from roads associated with mining facilities. These measures should include:

  • providing buffer zones of at least 100 m between roads and water bodies to the extent practicable; and
  • designing road grades and ditches to limit the potential for erosion, including avoiding road grades exceeding 12% (5% near water bodies).
R 333On-Site Roads and Access RoadsStream crossings for roads should be designed and constructed in a manner that protects fish and fish habitat. In particular, design and construction should prevent sedimentation of the streams and not obstruct movement of fish. Where stream crossings have the potential to alter or destroy fish habitat, the Policy for the Management of Fish Habitat (1986), prepared by the Department of Fisheries and Oceans, should be consulted. In designing crossings, the Fish Habitat Manual: Guidelines and Procedures for Watercourse Crossings in Alberta prepared by Alberta Transportation may be consulted.
R 334Disposal of SnowLocations for the disposal of snow should be identified. Snow should not be disposed of directly into lakes and streams or onto any ice-covered water body. Groundwater recharge areas, wetlands and areas with sensitive vegetation should be avoided. Measures should be taken to prevent contamination of water bodies by runoff from snow disposal areas, such as by directing runoff to settling ponds prior to discharge. Snow should be piled down from south to north. The south side will melt first and water will flow around or under the pile rather than over potential contaminants left upstream.
R 335PipelinesThe routes of pipelines should be selected so as to limit risk of harm to aquatic and terrestrial ecosystems in the event of a failure. Pipelines should be designed to reduce the risk of failure, and measures should be in place to limit impacts in the event of a failure. Once operational, pipelines should be inspected on a regular basis to ensure they are in good condition, and monitoring systems should be in place to alert operators in the event of a potential problem.
R 336Conveyor SystemsThe routes of conveyor systems should be selected so as to limit risks to the environment or human health from airborne particulate matter associated with the systems. To the extent feasible, conveyor systems should be enclosed to prevent or limit the release of airborne particulate matter. Loading and off-loading facilities for conveyor systems should be enclosed or other measures should be in place to prevent or limit the release of airborne particulate matter from loading and off-loading operations.
R 337Clearing of Vegetation

Clearing of vegetation in preparation for construction should be carried out in such a way that:

  • the area cleared is minimized;
  • buffer zones of natural vegetative cover of at least 100 m are retained wherever possible between cleared areas and adjacent bodies of water; and
  • the time between clearing of an area and subsequent development is minimized.

Note that the first two bullets also apply during the exploration and feasibility phase, particularly in the context of establishing camps and access roads and stripping outcrops.

Where feasible, vegetation from cleared areas may be replanted in nearby habitats for future relocation following mine closure.

R 338Preservation and Stockpiling of OverburdenSite-specific procedures should be developed and implemented to ensure that overburden, particularly organic soils, excavated from the mine site during construction is preserved and stockpiled for future reuse in site reclamation. Facilities for stockpiling should be designed to prevent or limit erosion of the stockpiled material by rainfall or wind. Measures should be put in place to ensure that stockpiled material is not contaminated during mine operations.
R 339Sedimentation Control

Site-specific plans for site erosion and sediment control should be developed and implemented. Measures that should be considered during the mine planning, construction, operations and closure phases include:

  • determining site erosion potential and identifying water bodies at risk;
  • establishing, to the extent possible, buffer zones of at least 100 m around water bodies that are at risk of sedimentation;
  • recontouring to reduce the susceptibility of soil to erosion;
  • revegetating and maintaining vegetated buffer zones adjacent to water bodies for erosion control;
  • diverting site drainage away from cleared, graded, or excavated areas;
  • using and maintaining sediment barriers or sediment traps to prevent or control sedimentation;
  • directing surface runoff from erodible areas to a settling pond prior to discharge to the environment; and
  • monitoring and maintaining the measures once they are in place to ensure they are effective.
R 340Northern Conditions and Permafrost

The planning and construction of mines in the North should be undertaken in a manner that minimizes impacts to the environment, including surface water and groundwater quality, fish and wildlife, natural habitat and other unique northern features such as permafrost. Activities should be planned with consideration of:

  • the project's requirements in terms of air landing strips, campsites or accommodation facilities, fuel and supply storage areas, survey lines and monuments, excavations, waste disposal and other infrastructure;
  • the geography and vegetation of the area, including natural features such as eskers, rivers, streams, lakes and ponds, and pingos; and
  • consideration of appropriate siting of mine components and monitoring of conditions that account for the presence of permafrost.
R 341Climate Change and Adaptation – Carbon ReductionStrategies for reducing carbon releases to the atmosphere should be considered and implemented throughout all phases of the mine life cycle. Carbon reduction opportunities should include the use of heavy equipment and vehicles that are fuel efficient and/or use alternative fuel.
R 342Climate Change and Adaptation – Sites in the Planning and Construction PhaseIn planning all aspects of mine operations, particularly water management and mine waste management and disposal, the potential impacts of climate change should be considered. Regional long-term predictions of climate change should be consulted, and predicted changes with respect to temperature, precipitation and extreme weather events should be taken into account. In areas of permafrost, the potential impacts of climate change should also be considered with respect to other aspects of site infrastructure, such as roads, pipelines, and on-site structures, all of which could be affected by deterioration of the permafrost. Any aspects of site infrastructure that could be affected by climate change should be planned, constructed and operated in a manner that will reduce or eliminate the potential impacts associated with climate change.
R 343Climate Change and Adaptation – Sites in the Mine Operations or Mine Closure PhasesOwners/operators of sites in the mine operations or mine closure phases should consult regional long-term predictions of climate change. A risk assessment should be carried out to identify any aspects of site infrastructure that could be affected by climate change, including predicted changes with respect to temperature, precipitation and extreme weather events. Measures to mitigate these risks should be planned and implemented in a manner that reduces or eliminates the potential impacts associated with climate change.


Table S.4: Environmental Management Practices for the Mine Operations Phase
NumberSubjectSummary of Recommendations: Environmental Management Practices for the Mine Operations Phase
R 401Water Management

Site-specific programs should be developed and implemented to monitor the quality of collected mine water and seepage from waste rock dumps and tailings management facilities. As a minimum, these programs should:

  • describe the surficial and subsurface geology, including aquifers and aquitards;
  • identify and characterize local groundwater resources and uses;
  • indicate the locations of mine water and seepage sampling stations and mine waste areas;
  • provide water sampling, handling and analyses protocols (where analyses are completed by outside laboratories, metal mines should have copies of the protocols used); and
  • provide a groundwater database that is updated as sampling is undertaken.
R 402Water Management

The hydrological models that were used in planning the water management system should be recalibrated. Data collected to complete this calibration should include:

  • climatic variables, such as precipitation, temperature, solar radiation, relative humidity, and wind speed and direction;
  • lake levels and snow pack thickness;
  • stream flow and effluent discharge rates; and
  • beaver activity and dam construction, where applicable.
R 403Water Management

Water management activities during the mine operations phase should include:

  • monitoring to check and report on the performance, status and safety of water management facilities;
  • inspection of pipelines for flow and hydraulic integrity;
  • monitoring of water quality and level in retention facilities, such as tailings management facilities, sedimentation ponds and polishing ponds; and
  • inspection of drainage ditches and dikes for sediment accumulation and bank erosion and damage; and
  • efforts to determine and implement ways to recycle water and reduce the use of fresh water as much as possible.
R 404Use of Tailings and Waste Rock as Mine BackfillWhere feasible, the owner/operator of a mine should use tailings and waste rock as mine backfill in order to reduce the quantities of these wastes that are placed in tailings management facilities and waste rock piles.
R 405Use of Tailings and Waste Rock as Mine BackfillTailings and waste rock being considered for use as mine backfill should be assessed to ensure that the material will be suitable for use as backfill, particularly if the material is to be used to provide structural support in underground mines. This should include an assessment of the physical as well as the chemical characteristics of the material to ensure that it has appropriate structural properties for use underground and to ensure that chemical alteration of the material will not compromise its structural properties or pose a risk to the environment.
R 406Use of Tailings and Waste Rock as Mine BackfillWhere potentially acid generating materials are used as mine backfill, monitoring measures should be implemented to assess impacts of the material on the quality of mine water and to predict potential impacts on the quality of mine water after mine closure. Potential impacts on regional groundwater quality should also be assessed.
R 407Management of Tailings Management Facilities

Tailings management facilities should be controlled and monitored using a formalized procedure that is incorporated into the mine's EMS. Key control and monitoring subject areas should include:

  • inspections of tailings management facilities with regard to performance monitoring, instability indicators, stability monitoring, tailings deposition, water management and control, and quality of effluent;
  • construction controls, including the use of a construction management program;
  • procedures for dust control; and
  • quality assurance and quality control measures for all aspects of operations, monitoring and inspections.
R 408Management of Tailings Management FacilitiesAll procedures related to the environmental management of tailings management facilities should be clearly documented, together with the roles and responsibilities of all relevant staff. This documentation should be revised as needed to ensure that it is up to date and accurate, and it should be maintained throughout the mine operations and mine closure phases.
R 409Monitoring of Waste Rock and Tailings

Site-specific waste rock and tailings monitoring programs should be designed and implemented to:

  • assess the potential of waste rock and tailings for metal leaching and acidic drainage;
  • verify predictions made during the mine planning phase;
  • collect data required for modelling;
  • assess the level of acid generation when oxidizing reactions are occurring, and assess acidity and reaction products that are potentially available to migrate;
  • evaluate the effectiveness of measures that have been implemented to prevent and control metal leaching and acidic drainage; and
  • identify potential surface seeps and groundwater contamination.
R 410Management of Treatment Sludge

Sludge that is a by-product of the treatment of mine effluent should be managed so that it will remain in a physically and chemically stable state. In this regard, a mine owner/operator should:

  • characterize treatment sludge to determine whether there are potential leaching concerns;
  • avoid disposal of treatment sludge with potentially acid generating wastes;
  • dispose of sludge in a physically secure facility under conditions that will maintain the chemical stability of the sludge; and
  • treat and monitor wastewater from the sludge management facility as necessary to ensure regulatory requirements are met.

In cases where a mine is predicted to produce large volumes of sludge over an extended period of time, the mine owner/operator should consider using a treatment process that produces a denser, lower volume sludge.

R 411Ammonia ManagementMines using ammonium-based explosives should adopt best management practices for blasting and for the handling of these explosives to avoid spillage and minimize ammonium residue remaining after blasting, thereby lowering the potential for ammonium contamination.
R 412Ammonia Management

Site-specific ammonia monitoring and management plans should be developed and implemented to assist in ensuring that final effluent is not acutely lethal and does not have an adverse impact on the receiving aquatic environment. As a minimum, the plans should:

  • identify potential sources of ammonia, including explosives and cyanate hydrolysis;
  • estimate ammonia loading and identify the need for additional controls if warranted; and
  • include procedures to assist in mitigating ammonia contributions from blasting agent spillage or other losses.
R 413Cyanide Management

Building on recommendation R 321, cyanide and cyanide-related materials should be transported, stored, used and disposed of in a manner consistent with the practices described in the International Cyanide Management Code (International Cyanide Management Institute, 2002). In particular, mines using cyanide should:

  • implement preventative and mitigative measures to protect fish and wildlife from direct and indirect discharges of cyanide process solutions to surface water and groundwater;
  • implement routine monitoring programs to evaluate the effects of cyanide exposure on wildlife, surface water and groundwater quality; and
  • plan and implement procedures for effective decommissioning of cyanide facilities to protect surface water and groundwater.
R 414Thiosalts Management

At sites where there is a risk of thiosalts occurring in wastewater from ore processing:

  • measures should be taken to minimize the discharge of thiosalt-bearing wastes to the environment either by recycling the water back to the ore processing facility or by implementing measures to ensure thiosalt degradation on site;
  • programs should be designed and implemented to monitor concentrations of thiosalts in wastewater as well as to check for pH depression downstream; and
  • treatment systems or mitigation measures should be put in place to minimize the concentration of thiosalts in effluent before it is discharged to the environment.
R 415Measures to Control Greenhouse Gas Emissions

Site-specific plans should be developed and implemented to minimize releases of greenhouse gases. Plans should describe:

  • potential sources of releases of greenhouse gases;
  • factors that may influence releases of greenhouse gases;
  • measures to minimize releases of greenhouse gases;
  • monitoring and reporting programs for releases of greenhouse gases;
  • mechanisms to incorporate the results of monitoring programs into further improvements to measures to minimize releases; and
  • mechanisms to periodically update the plans.
R 416Measures to Control Releases of Airborne Particulate Matter

Site-specific plans should be developed and implemented to minimize releases of airborne particulate matter. These plans should describe:

  • potential sources of releases of airborne particulate matter, including specific activities and specific components of mine infrastructure;
  • factors that may influence releases of airborne particulate matter, including climate and wind;
  • potential risks to the environment and human health from releases of airborne particulate matter;
  • measures to minimize releases of airborne particulate matter from the sources identified;
  • monitoring programs for local weather, for consideration in the ongoing management of releases of airborne particulate matter;
  • monitoring and reporting programs for releases of airborne particulate matter and for environmental impacts of releases;
  • mechanisms to incorporate the results of monitoring programs into further improvements to measures to minimize releases; and
  • mechanisms to periodically update the plans.
R 417Measures to Control Releases of Airborne Particulate MatterConsistent with the Canada Wide Standard for particulate matter (PM), the concentration of particulate matter less than 2.5 microns in size (PM2.5) should not exceed 15 µg/m3 (24-hour averaging time) outside the boundary of a mining facility.
R 418Measures to Control Noise

Site-specific assessments should be conducted to identify sources, or potential sources, of noise, and measures should be implemented to reduce noise levels from these sources. Such measures should include consideration of:

  • elimination of noise sources;
  • the purchase of equipment with improved noise characteristics;
  • proper maintenance of equipment;
  • enclosure or shielding of sources of noise;
  • suppression of the noise at source;
  • locating noise sources to allow natural attenuation to reduce levels to potential recipients; and
  • the operation of noise sources only during hours agreed to in consultation with local communities.

Monitoring should be conducted to assess the effectiveness of these measures and to plan further improvements in noise reduction.

R 419Ambient Noise from Mining OperationsIn residential areas adjacent to mine sites, the equilibrium sound pressure level (Leq) from mining activities should not exceed 55 dBA during the day and 45 dBA at night. Ambient noise can also affect wildlife, so sites in remote locations should also work to meet these objectives for off-site ambient noise levels.
R 420Control of Noise and Vibration from Blasting

Mines in areas where ground vibration and noise from blasting are not regulated should design their blasts so that the following criteria are not exceeded at or beyond the boundaries of the mine property:

  • ground vibration of 12.5 mm/sec peak particle velocity measured below grade or less than 1 metre above grade; and
  • concussion noise of a maximum of 128 dB.
R 421Blasting in or Adjacent to Fish-Bearing Water BodiesBlasting conducted in or adjacent to any fish-bearing water body should be done in accordance with the Guidelines for the Use of Explosives in or near Canadian Fisheries Waters, prepared by the Department of Fisheries and Oceans (1998).
R 422Engine Operation and Maintenance

Engines in vehicles and stationary equipment should be maintained and operated in a manner that minimizes emissions of criteria air contaminants, particularly:

  • total particulate matter (TPM);
  • particulate matter less than or equal to 10 microns (PM10);
  • particulate matter less than or equal to 2.5 microns (PM2.5);
  • sulphur oxides (SOx);
  • nitrogen oxides (NOx);
  • volatile organic compounds (VOCs); and
  • carbon monoxide (CO).
R 423Engine Operation and MaintenanceMaintenance shops should be operated to ensure that potential contaminants, such as used lubricants, batteries and other wastes, are properly managed. Appropriate disposal mechanisms should also be in place for these materials. Stores should be managed such that potentially hazardous materials are handled in accordance with procedures detailed in the environmental management system for the mine.
R 424Progressive ReclamationProgressive reclamation should be undertaken over the mine life cycle to reduce environmental impacts and the amount of work to be done during the mine closure phase. The owner/operator of each metal mine should develop a site-specific progressive reclamation schedule as part of the closure plan. The schedule should be used by mine staff to monitor the status of progressive reclamation activities, and the schedule should be updated on a regular basis. Progressive reclamation activities should be consistent with the site-specific objectives for mine closure and the intended post-closure land use for the site.
R 425Progressive Reclamation of Waste Rock Piles and Tailings Management Facilities

Progressive reclamation of waste rock piles and tailings management facilities should be carried out during the mine operations phase, to the extent feasible. Progressive reclamation activities should be carried out in a manner consistent with the site-specific objectives for mine closure and the intended post-closure land use for the site, as identified in the closure plan. The planning and implementation of progressive reclamation measures should include consideration of:

  • the final contouring of waste rock piles;
  • the establishment of a final drainage system;
  • the establishment of wet covers or dry covers, where these cover systems are to be used to prevent or control acidic drainage; and
  • the revegetation of exposed areas.
R 426Progressive Reclamation of Mine Site InfrastructureProgressive reclamation of mine site infrastructure should be carried out during the mine operations phase, to the extent feasible. This may include roads which are no longer used and areas affected during earlier activities, such as drill pads or campsites established during the exploration or construction phases.


Table S.5: Environmental Management Practices for the Mine Closure Phase
NumberSubjectSummary of Recommendations: Environmental Management Practices for the Mine Closure Phase
R 501Evaluation of Revision of Existing Environmental Plans

At the end of the mine operations phase and throughout the mine closure phase, plans to manage various environmental aspects of the mine that were established and implemented earlier in the mine life cycle should be evaluated and revised to ensure that they remain appropriate for the changing conditions of mine closure. In particular, consideration should be given to the evaluation and revision of the following:

  • pollution prevention plans;
  • environmental management plans;
  • plans for the monitoring and inspection of environmental facilities;
  • plans for environmental monitoring; and
  • emergency plans.
R 502Mine Closure CostsThe anticipated costs of mine closure should be re-evaluated regularly throughout the mine life cycle. The mine owner/operator should ensure that adequate funds are available to cover all closure costs, and the amounts of any security deposits should be adjusted accordingly.
R 503Financing Long-term Monitoring, Maintenance or TreatmentAt sites where it is determined that long-term monitoring, maintenance or effluent treatment will be necessary post closure, mechanisms should be identified and implemented that will ensure that adequate and stable long-term funding is available for these activities. In determining funding levels required, consideration should be given to contingency requirements in the event of changes in economic conditions, system failures, or major repair work post closure.
R 504Suspended Operations and Inactive MinesEach mine should develop a plan for the care and maintenance of the mine site in the event that mine operations are suspended or the mine otherwise becomes inactive. The plan should include continued monitoring and assessment of the environmental performance of the site, as well as the maintenance of all environmental controls necessary to ensure continued compliance with relevant regulatory requirements.
R 505Aspects to be Considered in Mine Closure

Mine closure activities should address the following environmental aspects:

  • underground and open pit mine workings;
  • ore processing facilities and site infrastructure;
  • waste rock piles and tailings management facilities;
  • sludge disposal areas as well as ongoing sludge disposal requirements, post closure;
  • water management facilities;
  • landfill and waste disposal facilities; and
  • exploration areas.
R 506Decommissioning of Underground and Open Pit Mine WorkingsIf it is technically and economically feasible to do so, underground or in-pit infrastructure (e.g., crushers, rails, metal structures, water and air pipes) and equipment (e.g., fans and pumps) should be removed from the site. Any equipment to be left underground or in the pit should be inspected and remediated as appropriate to ensure that there is no risk of leakage of any contaminants.
R 507Decommissioning of Underground and Open Pit Mine WorkingsDuring the decommissioning of underground and open pit mines, any contamination associated with vehicle and equipment operations and maintenance should be identified and remediated, as appropriate.
R 508Decommissioning of Underground and Open Pit Mine WorkingsUnderground mine workings should be secured and signs should be posted warning the public of potential dangers associated with the facility. In the event that underground openings are utilized by bats, gates should be installed that allow for continued access by them, while protecting the public.
R 509Decommissioning of Underground and Open Pit Mine WorkingsThe risk of subsidence in underground mines should be assessed. Appropriate measures should be taken to prevent subsidence in cases where the risk of subsidence is determined to be significant. The primary measure used to prevent subsidence is the backfilling of underground voids.
R 510Decommissioning of Underground and Open Pit Mine WorkingsOpen pits should be backfilled or flooded to the extent practicable to prevent unauthorized access and to protect public safety. In cases where backfilling or flooding is not practically feasible, fencing should be installed to protect the public. In all cases, signs should be posted warning the public of potential dangers associated with the site.
R 511Decommissioning of Underground and Open Pit Mine WorkingsThe potential for mine water discharges should be assessed. For underground mines, this should be done using a hydrogeological assessment. For open pit mines, this may be done using water balance calculations and, in some cases, hydrogeological assessment. Where mine water discharge is predicted, the flow rate should be estimated.
R 512Decommissioning of Underground and Open Pit Mine WorkingsWhere there is the potential of mine water discharge after mine closure, the quality of the discharge should be predicted. Mine water quality should be assessed once closure has been completed to verify the accuracy of the predictions.
R 513Decommissioning of Underground and Open Pit Mine WorkingsWhere there is the potential of mine water discharge of poor quality, measures should be implemented to prevent or control that discharge and to collect the mine water for treatment. Prevention methods may include capping of mine openings to prevent mine water discharge.
R 514Decommissioning of Underground and Open Pit Mine WorkingsOn-site facilities and equipment that are no longer needed should be removed and disposed of in a safe manner, unless facilities or equipment are to be preserved for post-closure land use. Efforts should be made to sell equipment for reuse elsewhere or to send equipment for recycling, rather than disposing of it in landfill facilities.
R 515Buildings and FoundationsThe walls of on-site buildings should be razed to the ground, except in cases where they are to be preserved for post-closure land use. Foundations should be removed or covered with a sufficiently thick layer of soil to support revegetation.
R 516Buildings and FoundationsIf buildings are to be preserved, either as a heritage resource or for some other post-closure land use, structures and foundations should be inspected to ensure that no contamination is present. If the structures or foundations are contaminated, they should be remediated as necessary to ensure public health and safety for post-closure land use.
R 517Support InfrastructureSupport infrastructure, such as fuel storage tanks, pipelines, conveyors and underground services, should be removed, except in cases where it is to be preserved for post-closure land use.
R 518RoadsThe main access road to the site (or runway in the case of remote sites) and other on-site roads, as appropriate, should be preserved in a sufficient condition to allow post-closure access for monitoring, inspection and maintenance activities.
R 519Roads

Roads, runways or railways that will not be preserved for post-closure use should be reclaimed:

  • bridges, culverts and pipes should be removed, natural stream flow should be restored, and stream banks should be stabilized by revegetating or by using rip-rap;
  • surfaces, shoulders, escarpments, steep slopes, regular and irregular benches, etc., should be rehabilitated to prevent erosion; and
  • surfaces and shoulders should be scarified, blended into natural contours, and revegetated.
R 520Electrical InfrastructureElectrical infrastructure, including pylons, electrical cables and transformers, should be dismantled and removed, except in cases where this infrastructure is to be preserved for post-closure land use or will be needed for post-closure monitoring, inspection and maintenance. This includes infrastructure on site as well as any off-site infrastructure owned by the mining company.
R 521Electrical InfrastructureIf polychlorinated biphenyls (PCBs) were used on site, any equipment contaminated with PCBs should be disposed of in accordance with relevant regulatory requirements. Soils and subsoils near electrical stations should be assessed to determine whether there is any contamination due to PCBs. If soils are contaminated with PCBs, this contamination should be mitigated in an appropriate manner.
R 522Waste Disposal and ContaminationWaste from the decommissioning of ore processing facilities and site infrastructure, such as waste from the demolition of buildings and the removal of equipment, should be removed from the site and stored in an appropriate waste disposal site or disposed of on site in an appropriate manner in accordance with relevant regulatory requirements. If material is disposed of on site, the location and contents of the disposal site should be documented.
R 523Waste Disposal and ContaminationSampling and analysis of soils and other materials should be conducted to ensure that none of the material is contaminated, e.g., with asbestos and mercury from buildings. If contaminated materials are identified, they should be handled and disposed of in an appropriate manner in accordance with all applicable regulatory requirements.
R 524Long-term Physical Stability of Waste Rock Piles and Tailings Management Facilities

At the end of the mine operations phase, detailed inspections and assessments of waste rock piles and tailings management facilities, particularly dams and other containment structures, should be carried out. The objective of these inspections and assessments is to evaluate the actual performance against design projections related to anticipated post-closure conditions. Factors that should be considered include:

  • the extent of deformation;
  • the rate and quality of seepage;
  • the condition of foundations and sidewalls; and
  • design loads, which may be different after mine closure.
R 525Long-term Physical Stability of Waste Rock Piles and Tailings Management Facilities

At the end of the mine operations phase, comprehensive risk assessment should be conducted for mine closure to:

  • evaluate the long-term risks associated with possible failure modes for waste rock piles and tailings management facilities;
  • identify possible impacts on the environment and human health and safety in the event of a failure;
  • determine parameters critical to these failure modes and possible impacts; and
  • develop and implement long-term control strategies to manage the identified risks.
R 526Long-term Physical Stability of Waste Rock Piles and Tailings Management Facilities

At sites where long-term risks are identified under recommendation R 525, a long-term monitoring and maintenance plan for waste rock piles and tailings management facilities should be developed and implemented, as appropriate, to ensure post-closure monitoring and maintenance of these facilities. This plan should include the following elements:

  • identification of roles and responsibilities of persons to be involved in monitoring and maintenance;
  • identification of aspects to be monitored and the frequency;
  • identification of routine maintenance activities to be conducted and the frequency;
  • description of contingency plans to address any problems identified during routine maintenance and monitoring.
R 527Prevention, Control and Treatment of Metal Leaching and Acidic Drainage

At the end of the mine operations phase, plans for management of waste rock and tailings to prevent, control and treat metal leaching and acidic drainage should be re-evaluated and revised as necessary, to ensure that they are consistent with the objectives and plans for mine closure and post closure. This evaluation should consider:

  • the results of the re-evaluation of the performance of these facilities;
  • the performance of progressive reclamation to date; and
  • possible alternative technologies for closure.
R 528Prevention, Control and Treatment of Metal Leaching and Acidic Drainage

At sites where there is an identified long-term risk of metal leaching or acidic drainage, the site-specific monitoring programs for waste rock and tailings developed under recommendation R 409 should be revised and updated to ensure that monitoring programs are consistent with objectives and plans of mine closure and post closure. The revised plans should include the following elements:

  • identification of roles and responsibilities of persons to be involved in monitoring;
  • identification of parameters to be monitored and the frequency; and
  • description of contingency plans to address any problems identified during routine monitoring.
R 529Closure in Permafrost ConditionsAt all mines that exist in permafrost conditions, downstream slopes of tailings containment structures should be revegetated.
R 530Decommissioning of Tailings from Uranium Mining FacilitiesAt uranium mines, measures should be taken in decommissioning tailings management facilities to prevent or control the release of radon gas. Such measures may include single or multiple soil layers involving waste rock and low- grade tailings or water covers.
R 531Water Management

At the end of the mine operations phase, water management plans should be evaluated and revised as necessary to ensure that they are consistent with the objectives and plans for mine closure and post closure. This evaluation should consider:

  • the results of an evaluation of the performance of the existing water management plan;
  • expected changes in water flow and water balance on site; and
  • expected changes in wastewater volume and composition.

Based on this evaluation, the following should be identified:

  • water management structures, such as dams and diversion ditches, that will no longer be needed, methods to be used for decommissioning these structures, and the timing of decommissioning;
  • water management structures that will continue to be needed and any long-term maintenance or replacement requirements associated with these structures;
  • water management structures that will need to be modified, methods to be used to modify these structures, the timing of modification, and any long-term maintenance requirements associated with these structures; and
  • long-term monitoring requirements to ensure that the water management system continues to function as designed.
R 532Long-term Treatment of Wastewater

At sites where it is determined that long-term treatment of wastewater will be necessary during post closure, a long-term wastewater treatment plan should be developed and implemented. This plan should include the following elements:

  • identification of roles and responsibilities of persons to be involved in operation and maintenance of the treatment system;
  • identification of the type of treatment system to be used;
  • identification of any by-products from the treatment system, such as treatment sludge, and management plans for the disposal of those by-products;
  • identification of routine maintenance activities to be conducted on the treatment system and the frequency;
  • identification of monitoring to assess ongoing performance of the treatment system and the frequency;
  • identification of reporting requirements for internal management and regulatory agencies; and
  • description of contingency plans to address any problems associated with the treatment system.

Consideration should be given to the implementation of a passive treatment system. In some cases, these systems may have lower maintenance requirements than traditional treatment systems, although all systems do require some degree of ongoing maintenance.

R 533Mine Site Rehabilitation and RevegetationPost-closure landscapes should be designed in a manner consistent with the objectives of mine closure and the intended post-closure use of the site.
R 534Mine Site Rehabilitation and RevegetationIn re-establishing soil cover on the site, consideration should be given to the characteristics of the soil that will be used as well as the soil requirements of the vegetation to be established on the site. Where possible, overburden that was stripped and stockpiled earlier in the mine life cycle should be used in the development of the reclamation surface. If this is not possible, or if there is insufficient stockpiled overburden, soil from a local source should be used to ensure similar soil conditions and avoid the importing of non-native seeds.
R 535Mine Site Rehabilitation and RevegetationSpecies used in revegetation and the resulting plant community should be consistent with the goals of mine closure and the intended post-closure use of the site. Species native to the area around the mine site should be used for this purpose, and invasive species should never be used.
R 536MonitoringMonitoring programs should be designed and implemented during mine closure to ensure that closure activities and any associated environmental effects are consistent with those predicted in the closure plan and to ensure that the objectives of mine closure are being met. Monitoring activities should include many of the monitoring activities conducted during the mine operations phase. Monitoring of aquatic and terrestrial ecosystems should continue until all work associated with mine closure is complete. Monitoring should also be conducted post closure to ensure that closure and rehabilitation measures are functioning as designed in accordance with applicable regulatory requirements.
Date modified: