Environmental Code of Practice for metal mines: summary

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.

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.

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.

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.

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).

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).

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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).

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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 (PM_2.5);
• sulphur oxides (SO_x);
• nitrogen oxides (NO_x);
• volatile organic compounds (VOCs); and
• carbon monoxide (CO).

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.