Chapter 9

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9.0 Acid Rock Drainage Management and Performance Assessment

9.1 Introduction
9.2 Developing Acid Rock Drainage Management Plans
9.2.1 Sustainability Considerations
9.2.2 Mine Life Cycle Considerations
9.2.3 Acid Rock Drainage Control – a Multidisciplinary Task
9.2.4 ARD Maturity and the Mine-Life Cycle
9.2.5 Design for Closure
9.2.6 Engineering Design Process
9.2.7 Risk Assessment, Management, and Contingency Plans
9.2.8 Monitoring Performance and Assessment of Success
9.3 Implementing the Acid Rock Drainage Management Plan
9.3.1 Integrating Acid Rock Drainage Management into Mine and Process Operations
9.3.2 Management System Roles and Responsibilities
9.4 Long-Term Considerations
9.4.1 Design Horizon
9.4.2 Long-Term Resources
9.4.3 Information/Institutional Knowledge Retention
9.4.4 Changing Standards/Stakeholder Needs and Expectations
9.5 References
List of Tables
List of Figures


9.0 Acid Rock Drainage Management and Performance Assessment

9.1 Introduction

The management of ARD and the assessment of its performance are usually described within the site environmental management plan or, in the case of a significant ARD issue, in a site-specific ARD management plan. The ARD management plan represents the integration of the concepts and technologies described in the previous chapters of this GARD Guide. It also references the engineering design processes and operational management systems employed by mining companies.

The comprehensive approach outlined in this chapter for the development and contents of an ARD management plan assumes that ARD is a significant issue for a mine project, operating or closed site. Only some elements of the approach contained in this chapter may be applied where ARD is a lesser issue.

The need for a formal ARD management plan is usually triggered by the results of a characterization and prediction program (Chapters 4 and 5) or the results of site monitoring (Chapter 8). For a mine project, the corporate staff coordinating the environmental input into a feasibility study are most likely to identify the requirement for an ARD management plan, while for an operating mine site, the environmental superintendent is most likely to identify the need for the plan or an update to an existing plan.

The development, implementation, and assessment of the ARD management plan will typically follow the sequence of steps illustrated in the flowchart in Figure 9-1. This sequence is similar to that illustrated in Figure 1-2 in Chapter 1; however, the ARD management plan provides more detail and it also provides performance assessment and monitoring.

Figure 9-1: Flowchart for Performance Assessment and Management Review
Image:FlowchartforPerformanceAssessment.gif


Characterization is the first step for the development of an ARD management plan, as shown in Figure 9-1. Characterization also includes consideration of the biophysical setting (e.g., CSM as described in Chapter 4), regulatory and legal registry, community and corporate requirements, and financial considerations. Clear goals and objectives are then established for the management plan. These goals and objectives might include the prevention of the development of acidic seeps and runoff or the meeting of specific water quality criteria. Characterization and prediction programs (as discussed in Chapters 4 and 5) identify the potential magnitude of the ARD issue and provide the basis for the selection and design of appropriate ARD prevention and mitigation technologies (Chapters 6 and 7). The design process includes an iterative series of steps in which ARD control technologies are assessed and then combined into a robust system of management and controls (ARD management plan) for the specific site. The initial mine design is used to develop the ARD management plan needed for an environmental assessment (EA). The final design is usually developed in parallel with project permitting.

The ARD management plan identifies materials and wastes for special management. Risk assessment and management are included in the plan to refine strategies and implementation steps. To be effective, the ARD management plan must be fully integrated with the mine plan. Operational controls such as SOPs, key performance indicators (KPIs) and QA/QC programs are established to guide the implementation. Roles, responsibilities, and accountabilities for mine operating staff to implement the ARD management plan are identified. Data management, analysis, and reporting schemes are developed to track progress of the plan.

In the next step of the ARD management plan, monitoring is conducted to assess the field performance compared to the design goals and objectives of the management plan. Assumptions made in the characterization and prediction programs and design of the prevention and mitigation plan are tested and revised or validated. “Learnings” from monitoring and assessment are assessed and incorporated into the plan as part of continuous improvement. Accountability for implementing the management plan is checked to ensure that those responsible are fully adhering to elements of the plan. Internal and external reviews, or audits, are often conducted of performance, management systems, and technical components to provide additional perspectives on the implementation of the ARD management plan. Review by site and corporate management of the entire plan is necessary to ensure that the plan continues to adhere to site and corporate policies. Further risk assessment and management is conducted at this stage to assess the effects of changing conditions or plan deviations. Finally, results are assessed against the goals. If the goals are met, performance assessment and monitoring continues throughout the mine life, with periodic rechecks against the goals. If the goals are not met, then redesign and re-evaluation of the management plan and performance assessment and monitoring systems for ARD prevention and mitigation are required. This additional work might also include further characterization and prediction assessments.

The process described in Figure 9-1 results in continuous improvement of the ARD management plan and implementation of the plan, and accommodates changes in the mine plan that is especially likely to occur at times of rising or falling metal prices. If the initial ARD management plan is robust, it can be more readily adapted to changes in the mine plan.

Implementing the ARD management plan relies on a hierarchy of management tools, as illustrated in Figure 9-2. Corporate policies help to define corporate or site standards, which lead to SOPs and KPIs that are specific to the site and guide operators in implementing the ARD management plan. Where corporate policies or standards do not exist, projects and operations should rely on industry best practice.

Figure 9-2: Hierarchy of Management Tools
Image:HierarchyofManagementTools.gif


In summary, the development, assessment, and continuous improvement of a site-specific ARD management plan is a continuum throughout the life of a mine.

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9.2 Developing Acid Rock Drainage Management Plans

The development of an ARD management plan requires a multidisciplinary approach that considers a number of site specific considerations. These considerations are discussed in Sections 9.2.1 and 9.2.2 below.

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9.2.1 Sustainability Considerations

The ARD management plan should consider the following sustainable development principles:

  • Commitment to regulatory requirements and corporate policies
  • Engagement of stakeholders in the planning and implementation of the ARD management plan to understand their expectations (see Chapter 10). The stakeholders of the ARD management include those internal and external to the mining operation (e.g., mining personnel, nearby communities, regulatory agencies, NGOs) and the mining company shareholders (because of the potential long-term economic impacts).
  • Environmental protection during all stages of the mine life cycle, especially during post closure
  • Adoption of a risk-based ARD management approach in a timely manner
  • Economic considerations with respect to the cost of ARD management plan implementation
  • Well-being of nearby communities during and following operations. Special attention should be given to social aspects of the communities such as access to specific sites of spiritual importance.
  • Transparency in the planning and implementation of the ARD management plan
  • Mine life-cycle considerations of environmental and community impacts and costs
  • Continuous improvement of ARD management throughout operations
  • Consideration of and integration with post-mining land use objectives and plans

The underlying concept is to evaluate, understand, and maximize the contributions that mining makes to sustainable development. Application of these concepts may result in the “bar being set higher” than conventional environmental permitting considerations. Instead of accepting mitigation of impacts, the application of sustainability concepts strives to maintain or improve overall community conditions. This approach has been accepted in a number of recent mining projects (e.g., Gibson, 2005) and presents some specific challenges for ARD management (see Chapter 10).

The Australian Department of Industry, Tourism and Resources (DITR) has developed a series of handbooks as part of their Leading Practice Sustainable Development Program for the Mining Industry that demonstrate a commitment to sustainable development through integration of environmental, economic and social aspects through all phases of mineral production (DITR, 2006-2008).

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9.2.2 Mine Life Cycle Considerations

Table 9-1 describes mine life cycle considerations for the development of an ARD management plan for various sources of ARD. Aspects of mine life-cycle considerations include characterization and prediction for new, operating, and closed mines and selection of ARD control technology. Characterization is divided between source investigation and source performance. This division of source investigation and source performance is done to distinguish between the characteristics of the potentially acid generating materials and how the materials will behave when placed in an on-site facility.

The project knowledge base is improved throughout the mine life cycle (e.g., Currey, 2008). Lessons learned from pilot tests, large-scale implementation, and monitoring are used to improve the designs and application so that the ARD management plan can provide efficient and effective environmental protection.

Table 9-1: Mine Life Cycle Considerations for the Development of ARD Management Plans
 

Project For New Mine

Operating Mine

Closed Mine
(Without Management Plan)

Comments

Characterization & Prediction

ARD sources

Limited until mine developed, other than usually minor sources that result from exploration programs.

Mine workings, waste rock piles, tailings deposit, infrastructure built from waste rock, spillages along conveying routes, wind-blown or stormwater-transported material, sediments in dams and watercourses and ore stockpiles.

Mine workings, waste rock piles, tailings deposit, infrastructure built from waste rock, spillages along conveying routes, wind-blown or stormwater-transported material, sediments in dams and watercourses.

Number and size of waste piles and extent of mine workings increase during mining life cycle. Risk also exists for interactions with sources on adjacent mines through inter-mine hydrological connections.

ARD maturity

Not started.

Mine workings and waste rock piles may be mature. Tailings immature or early stage of ARD evolution due to reduced permeability and high water content. Maturity of fugitive sources (spillage, windblown, sediments) may vary.

Mine workings, waste rock piles, tailings and fugitive sources all mature for surface drainage. Tailings yield to groundwater may be immature. Relevance of off-site sources from inter-mine flow depends on circumstances.

Maturity depends on time of exposure to air and moisture.

Information available for characterization and prediction

Drill core, samples from trenches and road cuts. Static and lab and field kinetic cell tests. Good mining geology understanding for source modeling. Important to integrate ARD data collection with mineral resource exploration drilling and sampling.

Drill core plus abundant rock exposures for sampling/testing. Field kinetic cell tests; field reconnaissance; lab tests, including leach extraction of aged waste; drainage water quality monitoring results. Good mining geology understanding and operating records for source and deposits modeling.

Field reconnaissance, drainage water quality monitoring, drilling and trenching to obtain aged samples for lab characterization, including leach extraction testing. Generally, poor geology and operating records for source and deposit modeling for historical mines. Variable historical plans & records of mining activities and depositional history for residue deposits.

Field reconnaissance includes color change observations and paste pH and conductivity testing of wastes. Direct sampling and testing of ARD becomes possible.

ARD model calibration

Calibration against experience at mines with similar deposit geology, mineralogy and mine development. Possibly lower reliability.

Calibrate against mine mapping and placement records, results from lab & field test cells, reconnaissance tests and early stage drainage water quality.

Possibly limited mine waste management records for characterization and modeling but good reconnaissance test results and drainage water quality for calibration.

Need for modeling and prediction reduces as ARD conditions mature. However long-term predictions necessary for post closure monitoring and maintenance plan development and determination/establishment of any post-closure financial provisions.

ARD Control Technology Selection And Management Plan Design

Selection of ARD control technology

All options applicable to the ARD mineral type and site specific conditions may be considered. ‘Design for closure’ and state-of-the-art practices can be applied to all mine elements. Provision can be made for appropriate management practices and optimization of use of mined materials. Able to maximize ‘prevention’ controls.

Options constrained for existing development and waste deposits. Future mining and ARD control measures can be optimized to most cost effectively implement ARD control and a desired closure condition. Can optimize use of suitable waste remaining to be mined. Possible increasing reliance on migration and collection and treatment controls although regular review of management plans will identify new ‘prevention’ controls.

Options severely constrained by methods of prior mining, waste rock piles and tailings site selection and deposit designs. Drainage collection and groundwater migration control might be difficult. Possible large accumulation of ARD products in waste deposits. Relying generally on migration controls and collection and treatment although ‘prevention’ principles can be incorporated into cover design.

Control measures involving best site selection, and materials handling to maximize prevention of ARD generation are possible only for new mines. Control of ARD for mines later in their lives is increasingly dependent on ARD migration controls (e.g., covers and in situ reactive barriers) and collection and treatment.


The opportunity for investigations and the information available for source and deposits modeling differ during the life cycle of a mine. At the start of exploration and mine design, there might be limited information on the nature of future potential ARD sources. Mine design and layout and characterization and prediction are based on laboratory testing that usually cannot be fully verified through field measurements and observations. However, there is the opportunity for both gathering information and for optimizing the selection and application of ARD control technologies through judicious interpretation of available test results, professional experience, and comparison with analogue sites. State-of-the-art practices and designs therefore can be incorporated into the ARD management plan. As the mine develops, the temporal behaviours of the exposed mineralized rock, mine, and process wastes become apparent.

Initiating development of an ARD characterization and management plan for an operating mine has reduced potential for using deposit characterization as a source of data because most of the delineation drilling will have been completed. However historical core libraries may be available and these can be invaluable in assessing ARD potential for an existing mine. Ore and waste can be mapped, sampled, and characterized as it is mined and processed. For an operating mine, many of the mine and process waste facilities will have already been sited and partly developed, thereby limiting the potential application of ARD prevention strategies. Depending on the age of the mine, best practices as documented in this GARD Guide may not have been applied throughout mine development. The existing developments must be investigated and characterized to determine the extent to which they represent potential ARD sources. The design of existing facilities may constrain the range of ARD technologies that are technically and economically viable.

Monitoring existing mine-waste facilities and mine voids (open pit, underground mine) provides valuable data on geochemical reaction rates under field conditions. Geochemical reconnaissance surveys, leach testing, and drainage water quality monitoring provide data for understanding the evolution and quality of ARD and maturity of these systems. The value of this post hoc information can be substantially enhanced if the depositional history of these facilities has been properly recorded (see Chapters 4 and 5).

Mine designs and operating practices can often be modified to incorporate ARD prevention strategies during operations that are then applied for the remainder of the mine life. The overall mine management plan should incorporate the ARD management strategy so that the final site condition at mine closure is consistent with closure objectives. There are more likely to be personnel and equipment resources available for both investigation/characterization and implementation of the management plan during mine operation than after decommissioning.

Where mines have closed without adequate consideration of ARD management, there is a need to forensically investigate all elements of the mine and process development (mine, waste rock piles, process tailings deposit, and infrastructure in which mine and process wastes were placed). Information relevant to ARD sources and characterization might not be available and a program of drilling and trenching with sampling, field reconnaissance, laboratory testing with leach extraction testing, and monitoring of ARD discharges from mine waste deposits is often required. ARD from waste deposits might have occurred.

At closed sites, the ARD generation process in mine workings and wastes may be evolving, depending on when mining ceased. In arid climates and wastes containing higher carbonate mineral content, that evolution may proceed slowly. Drainage patterns in arid climates will also be different than those in wetter climates (e.g., compared to freshet effects in temperate climates). Therefore, characterization must consider and assess the stage of the ARD process.

ARD control options are limited, both technically and financially, by the physical constraints of the closed mine. Materials required for ARD control, such as cover materials, might not have been stockpiled from disturbed land or from appropriate selectively handled and placed waste and it may be necessary to disturb additional areas to develop borrow sources. Access, personnel, and equipment resources may be limited in remote locales. Disturbance of mature oxidizing mine waste can release large loads of ARD products and relocation and disturbance of such material must be done with appropriate caution and safeguards.

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9.2.3 Acid Rock Drainage Control – a Multidisciplinary Task

The development of an ARD management plan requires the integration of a number of technical disciplines. Some of the disciplines most commonly required are listed in Table 9-2.

In addition to the specialists listed in Table 9-2, there are numerous other skilled personnel involved in plan development and implementation. These include drillers and excavation samplers for procurement of samples, laboratory technicians skilled in mineral and ARD characterization testing, monitoring instrumentation technicians, and technicians and supervisors responsible for facility construction, rock placement, water management, water quality sampling, covers installation, and revegetation.

Often project development staff at the corporate level develops the mine plan during the feasibility stage of a project. Environmental and ARD specialists need to work closely with mine planners and metallurgists to identify opportunities to prevent ARD and to ensure ARD management is fully integrated into the mine plan and feasibility study. For example, opportunities to segregate NAG and PAG waste rock and tailing may become apparent during project design. Implementation of segregation requires that mine planners and metallurgists integrate ARD considerations into their feasibility activities. Figure 9-3 shows an open pit bench plan developed during the feasibility phase of a mine project. Results of ARD block modeling are integrated with ore and waste block modeling to show how segregation of NAG and PAG waste rock can be achieved at the individual mine bench level. These plans and other more detailed plans will be used by mine operations staff to define shovel cuts and haul truck destinations. Figure 9-4 illustrates the overall segregation of various waste rock units based on their ARD potential and physical characteristics.

Table 9-2: Technical Disciplines Involved in the Development of an ARD Management Plan

Discipline

Typical Involvement

Geology To define the geological distribution of rock types and mineralogy, for developing the geological model on which the geochemical zones and their characterization are developed.
Mineralogy To identify minerals that control the oxidation and neutralization potential and products.
Geochemistry To evaluate the oxidation and neutralization processes, dissolution, and solubility controls that determine mine water quality, modeling of ARD, and the determination of ARD control requirements.
Mining engineering and planning To develop the mining methods and schedules for waste extraction and ore placed in stockpiles and waste rock dumps, and for integration of the ARD management plan into mining operations.
Mineral processing/metallurgy To determine the characteristics of the heap leach, milled wastes or tailings and the control technologies that can be applied in processing to minimize ARD potential.
Analytical chemistry To support mine and metallurgical operations by implementing proper test methods for sample handling.
Water treatment To design water treatment plants to remove deleterious constituents in ARD and supervise water treatment plant operations.
Geotechnical engineering To design pit slopes and waste storage facilities such as tailings dams and waste rock piles, covers, and erosion stability of the post closure drainage system and landforms.
Social sciences To ensure effective and open communication with stakeholders and to ensure that their concerns are integrated into the management plan.
Hydrogeology To evaluate groundwater inflows to underground and open pit mines and groundwater flows that have contact with ARD sources.
Hydrology and limnology To determine flood flows and water balance required for design water management facilities.
Soil sciences To design and implement surficial soils (covers) in the closure landscape to facilitate growth of self sustaining vegetation.
Agronomy/botany forestry To evaluate sustainable vegetation to meet the management plan and closure objectives.
Biology/ecology To evaluate ecological impacts of residual surface and groundwater contamination and establish conditions for ecosystems of restored lands that meets operating and closure objectives.
Environmental law To determine the regulatory requirements that the mine needs to comply with
Accounting and financial management To estimate and monitor costs, and make appropriate provisions for funding the management plan and sustain post-closure monitoring and maintenance requirements.
Contract management To ensure that ARD management plan issues and measures are incorporated into all relevant contracts that the mine enters into with suppliers and contractors.
Project management and supervision To manage and supervise all aspects of management plan development and implementation, including long-term post closure activities, where applicable.
Senior management To ensure management plan adherence, implementation and continuous improvement are incorporated into the key performance indicators of all relevant personnel.
   


Figure 9-3: Open Pit Bench Plan Developed During the Feasibility Phase of a Mine Project
Image:OpenPitBenchPlanDevelopedDuringtheFeasibility.gif


Figure 9-4: Overall Segregation of Various Waste Rock Units Based on their ARD Potential and Physical Characteristics
Image:OverallSegregationofVariousWasteRockUnits.gif


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9.2.4 ARD Maturity and the Mine-Life Cycle

The time to onset of ARD conditions often depends on the geochemical and physical characteristics of the ARD sources and may take many years. For highly reactive sources, the maximum ARD load (concentration of contaminants and flows) may occur during the operating stage of the mine life. For others, the maximum ARD load may develop some time after mine closure.

Minimizing sulphide oxidation, preferably to extremely slow or negligible rates, by implementing ARD prevention measures, is the principal goal of the ARD management plan.

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9.2.5 Design for Closure

With an ARD management plan in place, the fundamental objective of performance assessment and monitoring is to determine the effectiveness of that plan rather than simply the evolution of the ARD process.

The concept of “design for closure” should be applied in the design of all mine and process facilities that have an ARD potential. Design for closure requires that the full mine-life cycle, from development to closure, be considered in the design of the mine components so that the desired mine closure conditions are achieved. Design for closure should also consider the potential, practical, and financial implications of temporary halting of operations or of early closure of the mine.

An example of the design for closure principle follows: If waste is placed above water and allowed to oxidize during the mine life then, at the time of mine closure, the waste material could contain large quantities of oxidation products. Subsequent placement below water could result in the release of large quantities of acidity and soluble metal contaminants, possibly rendering the subaqueous placement uneconomic or environmentally unacceptable. Applying “design for closure” at the time of initial waste storage facility design recognizes the need to place wastes underwater before there is significant oxidation and accumulation of oxidation products.

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9.2.6 Engineering Design Process

In concept, the engineering design process evaluates a range of technologies or control measures to identify the most effective and cost-effective option (or options) that will meet objectives. The expected performance of these alternatives or options can be evaluated using modeling and other approaches, and the outcomes can be compared to the site-specific goals and objectives. Cost estimates and other aspects (e.g., security of approach, risk, ease of implementation) are assessed to compare the different alternatives or options and thereby select the preferred option for implementation. This is an iterative process that may require a series of cycles of analyses, alternative technologies, and prediction to arrive at the preferred alternative.

Selecting technologies or control measures is dependent on the site conditions, including climate, geochemical characteristics of rock materials, and site topography. At some sites, the concerns may be focused on only one issue, such as potential ARD seepage from a tailings or mine rock facility. At other sites, a wide range of ARD concerns may have to be addressed, such as potential seepage from waste rock piles, runoff from process tailings embankments, runoff from mineralized pit slopes, and discharge from underground mine workings.

When only one concern is identified, there may be only a very limited number of applicable control measures to consider. Technologies can be identified for source control, migration control, and treatment options. For example, the technologies for preventing ARD seepage from a waste rock pile can include waste rock segregation and selective placement, encapsulation of waste rock to limit infiltration, and addition of lime to delay the onset of ARD until a cover can be constructed (see Chapter 6).

During the selection process of the control technologies, conceptual designs are developed for each technology option. The design process is iterative because a conceptual design is developed and then updated as more information becomes available or more detailed site information is obtained. Each of the technologies should be considered and then evaluated, first using qualitative screening based on advantages and disadvantages of each. The remaining technologies should then be evaluated using, for example, site-specific modeling or cost estimation. The result is the selection of a preferred technology or group of technologies that can be combined to satisfy the goals of the ARD management plan.

When there are multiple sources of ARD, the technologies or control measures for each source should be listed. Alternatives or options are then developed by combining a series of appropriate technologies. Conceptual designs are developed for each alternative so that site-specific modeling and cost estimation can be completed. Each alternative is screened using qualitative and quantitative approaches. Experienced engineers and scientists should work together in a team to accomplish this task because the complexity can increase dramatically with multiple sources, technologies, and alternatives. The outcome of this process is a plan for all the potential ARD sources, including the preferred alternatives or options that will satisfy all the goals.

9.2.6.1 Evaluation and Selection of Preferred Option

As described in Chapter 6, there are many technologies that may be considered for ARD control in the design of each of the mine components. For example, both the process tailings and waste rock may be placed below water (water covers) or stored in drained piles under dry covers of various types.

The combinations of control technologies that address all components are “options” for an ARD management plan. Various combinations of alternative control measures may be considered in a number of “options.” There are typically many advantages and disadvantages for each option identified.

A number of decision tools have been developed to assist the selection process. One is the Multiple Accounts Analysis (MAA) (Robertson and Shaw, 2004; Shaw et al., 2001). The method involves the following three basic steps:

1. Identify the impacts (benefits and costs) to be included in the evaluation 2. Quantify the impacts (benefits and costs) 3. Assess the combined or accumulated impacts for each option, and compare these with other alternatives to develop a preference list (ranking, scaling, and weighting) of the alternatives

The risk associated with each ARD management option is an important consideration and should be embodied in the assessment of values for indicators.

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9.2.7 Risk Assessment, Management, and Contingency Plans

Risk assessment is widely used in the mining industry to identify and evaluate risks and develop risk management strategies and contingency plans. The basic process is described in Chapter 3. This Section 9.2.7 discusses two approaches for risk assessment that might be applied to evaluating the potential success of the ARD management plan: a failure mode and effects analysis (FMEA) and environmental risk assessment (ERA). FMEA may be best suited for engineering designs and potential consequences that may result from a failure, while an ERA focuses more directly on potential environmental effects.

Failure Mode and Effects Analysis

Haimes (2004) describes a FMEA as a method that is “widely used for reliability analysis of systems, subsystems, and individual components of systems.” FMEA constitutes an enabling mechanism to identify the multiple paths of system failures. A prerequisite for an effective risk assessment process is to identify “all conceivable failure modes of a system.” A team of cross-disciplinary experts is required to construct an effective FMEA. The team should ideally include a representative that can speak for the interests of the local community (see Chapter 10). Dushnisky and Vick (1994) describe the FMEA process as applied to mining projects.

Multiple FMEAs may be performed on ARD management during a mine’s life cycle, especially as new information becomes available, projects expand, or new technologies develop. It is essential, though, to perform a risk assessment, FMEA, or other risk assessment approach to identify the selected alternative or option for ARD management.

A small team of experts representing various stakeholders should be assembled for a one or two day facilitated workshop to perform the FMEA. The experts should also represent different disciplines associated with the ARD management plan and they should have the same basic knowledge and understanding about the site conditions. The boundaries of the FMEA should be established before the workshop in terms of their physical and temporal extent. For example, the physical boundaries may include a single facility on a mine site, such as a waste rock facility or the whole mine site. Temporal boundaries may include the life of the mine plus a 20-year, or longer, post mining period. It is also useful to identify some conceptual failure modes before the workshop.

During the risk workshop, a full list of realistic failure modes is identified and described using a matrix where failure mode, effects of failure, likelihood of failure, consequences, and confidence in analysis must be identified. Failure likelihood and consequences are expressed in five descriptors (‘not likely,’ ‘low,’ ‘moderate,’ ‘high,’ and ‘expected’ for failure likelihood and ‘negligible,’ low,’ ‘moderate,’ ‘high,’ and ‘extreme’ for consequences). The consequences can include financial, reputational, regulatory and legal, and others that are appropriate for the site conditions. The failure likelihood and consequences are combined using a matrix such as the one provided in Table 9-3. Agreement on the descriptions and boundaries used for each of the likelihoods, consequences, and confidence levels should be established early during the workshop. Failure modes of high concern can then be identified according to the “warm” colors (upper right quadrant) in Table 9-3. For instance, if a failure mode has a high likelihood of occurrence and the consequence of failure with respect to a specific item such as regulatory and legal is considered extreme, then the risk will be in the “dark orange” area and will be of high concern.

Table 9-3: FMEA Outcomes Combining Likelihood of Failure and Consequences

Consequence

 

Likelihood

Not Likely

Low

Moderate

High

Expected

Extreme

 

 

 

 

 

High

 

 

 

 

 

Moderate

 

 

 

 

 

Low

 

 

 

 

 

Negligible

 

 

 

 

 


A risk management strategy is selected from various options for each high and at least moderate risk failure modes. The selected options that comprise the risk management plan can be preventive (to reduce the likelihood of the “failure”) or mitigative (to address potential consequences), or both.

Environmental Risk Assessment

The ERA considers probabilities and potential consequences of ARD/ML to an environmental component. An ERA may consider one specific issue, for example, the risk of surface water impact to a single aquatic species, or the issue may be much broader. The basic approach remains the same: identify a hazard (or failure mode) and pathway and the consequences of such a failure. The combination of these hazards and consequences represents the risk. Chapters 3 and 4 provide additional information on the environmental risk assessment process.

Risk Modeling

Risk models incorporate risk into scientific and engineering models. Risk models define risk according to the objectives of the system under consideration and the nature and risk tolerance of the various stakeholders involved. Modelling codes used for evaluation of risk generally include specific features that support decision analysis, such as in the STELLA and GoldSim codes. These codes allow for calculation of probability density functions (PDF) that take into account model input uncertainty and are suited to the evaluation of sensitivity analyses and “what-if” scenarios.

In many instances, the data available to adequately address stakeholders’ perceptions and needs are insufficient, in particular, in the case of very complex systems that are expected to function or persist for long periods of time. For instance, the consequences of a processing tailings dam failure at a closed site can be catastrophic when the tailings are acid generating and a permanent water cover has been constructed as part of the closure strategy. On the other hand, failure of a dry stack of chemically inert tailings is much less likely to have as significant an impact because of the lack of a transport medium and chemical reactivity. Risk models, therefore, are important tools to help identify and implement mine waste management measures needed to prevent or minimize, or both prevent and minimize, potential impacts.

Contingency Plans

Contingency plans are developed for those failure modes where a significant residual risk remains after the application of ARD prevention and control approaches. A contingency plan should include targeted monitoring, trigger levels for actions, and specific responses in case a certain event should occur. For example, if a failure mode is the potential for ARD seepage from a waste rock pile, then monitoring can be established for sulphate concentrations in waste rock seepage as an early indicator of potential ARD formation. If significant increases in sulphate concentrations are measured, then contingency measures such as covers, drainage collection, or more restrictive segregation criteria might be implemented.

Contingency plans, or adaptive management, must have clear monitoring targets and actions associated with specific events and outcomes.

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9.2.8 Monitoring Performance and Assessment of Success

To achieve the objectives of a management plan, both the implementation and the results of implementation of an ARD management plan must be monitored. Implementation indicators reflect how well the management plan is being executed. Performance indicators reflect how well elements of the management plan are performing against expected performance values. Monitoring involves the measurement of implementation and performance in accordance with indicators. Assessment involves the comparison of observed indicator values compared to expected values.

If assessment indicates that achieved implementation indicators vary significantly from the values established in the management plan, then implementation must be adjusted to meet the required indicator values, or the management plan has to be modified. Examples of implementation indicators are as-built records compared with design values of the tailings dam and waste rock piles, and placement of ARD mine wastes in the correct locations specified in the management plan.

If assessment indicates that achieved performance indicators vary significantly from the expected values in the management plan, then the management plan must be modified to achieve the desired performance (objectives). Examples of performance indicators are seepage water quality from waste rock piles or in groundwater quality as compared to anticipated quality, and treated water discharge qualities compared with treatment quality objectives. Individual indicators must be established to determine what will be monitored and how monitoring will be conducted. Groundwater quality monitoring can be established by selecting groundwater sampling locations and the analytical parameters. Measured concentrations are indicator values, and these values can be compared with groundwater concentration objectives for that location as well as the concentration changes anticipated over time in the management plan. To enable the rapid assessment of implementation and performance, trigger values should be established for ‘alerts’ and ‘response’ actions. When an ‘alert’ value is reached during monitoring, an increased level of monitoring and assessment is triggered. When a ‘response’ value is reached, the required assessment and response actions (e.g., contingency measures) should be initiated.

Table 9-4 provides a broad grouping and listing of typical implementation and performance indicators that could be applied to monitor and assess implementation and performance of an ARD management plan. This listing does not cover all possibilities and other approaches may be feasible or desirable.

The general descriptions of performance indicators, shown in Table 9-4, must be translated into specific observations, measurements, or tests that are sufficient to understand the nature and behaviour of each major element of the ARD management plan.

A number of indicators may provide a greater understanding of a current condition or the rate of change, although there is no single program of monitoring that is applicable to all mine sites. An example is the suite of parameters that can be measured and monitored to define the state of oxidation and contaminant release from a mine waste rock facility, including monitoring of temperature, gases (O2 and CO2), stored ARD products accumulating in the pile, surface and groundwater quality in the seeps or downstream environment, or the productivity and abundance of biota in the receiving environment. The various attributes of these different indicators for assessing different control technologies are summarized in Table 9-4. The selection of the most appropriate key indicators will depend on the performance issues that are of most relevance to both assessing and demonstrating the success of the management plan.

Seep flow rate measurements are often early and sensitive indicators of performance of stockpile or waste rock pile infiltration and contaminant transport control measures. Combined with water quality testing, flow measurements support calculation of the loads of contaminant releases to surface water, and flow measurements therefore are key performance indicators. Monitoring approaches for on-site and off-site facilities and receptors are described in Chapter 8.

Performance indicators should be carefully selected to optimize both the number and frequency of observations or sampling and the complexity of monitoring. Indicators that most directly represent the properties or effects of interest are usually the most accurate indicators. The frequency of measurements or observations should take into account rates of change; periods of monitoring should be limited to periods when the indicator is relevant and there should be regular reviews of indicators and their relevance to determine if monitoring of some parameters should be terminated, or if others should be introduced.

Table 9-4: Monitoring and Performance Assessment of Success

Monitoring Purpose

Assessment Questions

Nature of Monitoring

Key Implementation & Performance Indicators

Sources Classification Monitoring mainly of performance indicators Are the waste rock characteristics as anticipated? Waste rock classifications, quantities & ARD properties. Variance of characteristics from those designed for in MP.1
Are tailings characteristics as anticipated? Tailings classifications, quantities & ARD properties. Variance of characteristics from those designed for in MP.
Are mine face exposure surface characteristics as anticipated? Mine face geometry, fracturing and ARD properties. Variance of characteristics from those designed for in MP.
Are other properties (e.g., groundwater and surface water) as anticipated? Climate, groundwater and surface water quality Variance of characteristics from those designed for in MP.
MP execution Monitoring mainly of implementation indicators Is mining plan, schedule, and face exposures in accordance with MP? Mapping of mine face development and ARD rock types exposed. Variance of as-mined geometry and rock classification from that designed for in the MP.
Is mine wastes and tailings management in accordance with MP? Record mine waste and tailings production, handling and placement. Variance of mine waste and tailings quantities and management from MP.
Are materials used for control element construction in accordance with MP specs? Sample and test construction materials in situ properties and placement locations. Construction material properties and placement locations variance from MP.
Are control structures being constructed in accordance with MP? Observe construction and check dimension and products. Produce as-built drawings. Variance of as-built construction from the design requirements in the MP.
Is ARD collection, treatment and water balance in accordance with MP? Measure flows and water quality, record treatment operations, and production results. Variance of ARD water flows, water balance, and treatment plant operation from MP.
Is the management and reporting structure in accordance with MP? Audit management and reporting structure implemented. Variance of management and reporting structure from MP.
Component Performance Monitoring mainly of performance indicators Under water deposits Monitoring depends on components and indicators of performance relative to each control technology. Key indicators can vary. Variance of observed from design values monitored for each control technology and component. Oxidation products (solids & liquids)
Under covers deposits Indicators of ARD generation Oxidation products and ARD seepage
Collection systems Indicators of/ARD generation % diversion; reliability/stability
Diversion systems Indicators of efficient diversion % collection; reliability/stability
Collection systems Indicators of efficient collection Reliability; unplanned discharges
ARD water storage systems Indicators of reliable storage Discharge quality and reliability
Water treatment systems Indicators of adequate treatment Density and stability
Sludge disposal systems Indicators of effective disposal Stability of material in disposal site
Performance trajectory Comparing change in performance with predicted change in performance – to enable model calibration and revise prediction Is the evolution of ARD from sources/deposits under the applied control measures developing in accordance with model predictions? That is, are the control systems working?  Monitoring involves the comparison of the predicted time history of change in indicator values with the time history observed values from field monitoring for the various sources/deposits. Variance of observed from predicted time history indicates need for recalibration of predictive models and reassessment of control measures effectiveness and requirements to meet MP long-term objectives.
Sources/deposits include: WQ during operation & flooding Potential to meet MP objectives
  Underground mine WQ during operations & closure (flooding) Potential to meet MP objectives
Open pit mine Drainage WQ, temp, O2, stability Potential to meet MP objectives
Waste rock facilities Pond & seepage WQ, stability Potential to meet MP objectives
Tailings dams Efficiency, erosion, stability Potential to meet MP objectives
Collection systems Efficiency, reliability, cost Potential to meet MP objectives
Treatment plants Density, stability Potential to meet MP objectives
Sludge disposal facilities Density, leachability Potential to meet MP objectives
Environmental impacts Monitoring mainly of performance indicators relating to environmental impacts Are the environmental impacts on the surface of the sources/deposits and in the receiving environment achieving MP objectives for the following: Monitoring of the potentially impacted environment; including the surfaces over sources and the downstream surface and groundwater environment Indicators used for monitoring environmental impacts are typically a measure of quantity and quality of the natural resources and biota over and downstream of sources/deposits.
Surface land use, aesthetics, and productivity? Vegetation; soil and terrestrial biota; appearance; land use. Vegetation & biota species abundance; productivity; appearance & land use.
Surface water quality in the receiving environment? Surface water flows and quality over and downstream. Flow rates; contaminant concentrations; aquatic productivity.
Groundwater quality in the receiving environment? Air quality and downwind deposition effects? Groundwater elevations and quality in around & downstream Groundwater elevations; contaminant concentrations.
Social impacts in the affected community? Air quality over and downwind deposits rates and amounts.
Ongoing impacts to the quality of life in affected communities.
Particulates in air; downwind deposits characteristics, and rates.
Community health, culture and recreational pursuits.
Economic impact in the affected community? Economic impacts to affected communities. Job opportunities, economic burden, sustained economic benefits.
Management and maintenance Sustainability Monitoring of both implementation and performance indicators relating primarily to long-term sustainability Are the ongoing management and maintenance (M&M) activities required in the MP sustainable during operations and very long-term? Aspects to be monitored and assessed include: Long-term implementation of fiscal, management, operating, & maintenance systems and performance and sustainability of these activities in accordance with MP and the MP objectives; including: Key implementation and performance indicators for sustainability of the management and maintenance activities include current indicators and assessments of change trajectory compared with predicted by the MP.
  • Financial sustainability of required M&M.
  • Size and performance of financial security relative to MP forecasts.
Value (size), security, and change in value of financial assurance.
Presence, completeness, authority, and effectiveness of management.
  • Sustainability of management structure.
  • Succession process for M&M and durability of custodianship.
Ongoing completion of monitoring requirements of MP.
  • Sustainability of monitoring activities.
  • Sustained success of completing monitoring activities of MP.
Ongoing completion of maintenance requirements of MP.
  • Sustainability of operating and maintenance activities.
  • Sustained success of completing maintenance activities of MP.
On-going completion of operating requirements of MP.

1MP – management plan

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9.3 Implementing the Acid Rock Drainage Management Plan

Ideally, the ARD management plan has been developed as part of the original mine plan and environmental assessment. General requirements for implementation of the management plan are often contained in permits issued by regulatory agencies. Appropriate senior-level management responsibility and accountability must be put in place, together with access to adequate human and financial resources, to implement the plan and audit its effectiveness. The ARD management plan, including its assessment of performance, should be shared with communities and other stakeholders as discussed in Chapter 10.

A key aspect in implementing the ARD management plan with regard to mine scheduling is to establish a practical basis whereby the management measures can be part of the short-range and long-range mine planning (see the Mt. Milligan Project mini case study for an example: Mt. Milligan Project). Operating environmental staff knowledgeable in the basis of the ARD management plan should participate in the ongoing operations planning meetings and the geologic assessments. The environmental staff should also explain the environmental and geochemical considerations in a way that is understandable and useable for mine production staff.

The transition from project development to mine operations is a critical period because details and commitments for ARD management can be lost. Ideally, operating staff participate in the final stages of mine feasibility and environmental assessment and permitting because they have first-hand knowledge of ARD management strategies, plans, and commitments.

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9.3.1 Integrating Acid Rock Drainage Management into Mine and Process Operations

In general, the mining industry has embraced EMS. EMS is widely applied at mine sites. Application of these systems is based on corporate environmental policy and follows a typical cycle of planning, implementation and operation, checking and corrective action, management review, and continual improvement. The schematic in Figure 9-5 shows a typical EMS cycle and its components.

Figure 9-5: Typical Environmental Management Model
Image:TypicalEnvironmentalManagementModel.gif

Various other environmental-related management plans exist at mines, such as a biodiversity management plans, closure plans, waste management plans, integrated waste and water management plans, monitoring plans, and various other mine development plans. ARD management plans are often connected to these plans as part of the overall EMS. Where ARD is a significant issue, ARD should have its own management plan with linkages to related plans in the EMS. Where ARD is a smaller issue, its management could be integrated into other plans of the EMS (e.g., as part of the environmental monitoring plan where prediction programs indicate a low ARD potential).

Typically, the EMS and the ARD management plan are reviewed annually with major revisions every 3 to 5 years or the EMS and ARD management plans might change when triggered by a major change in operations (e.g., new ore body or metallurgical process).


ARD management plans are also an integral part of closure plans where ARD is a significant issue. Closure plans may be somewhat conceptual early in the mine life but closure plans become more specific as mining progresses. Closure plans should be quite detailed about 3 to 5 years before the completion of mining operations. Closure plans should be integrated into mine production plans and, in the last years of mine operations, become a large part of the production plan in order to make effective use of mine site resources.

Additional features of a successful corporate or site-level ARD management structure include the following:

  • Incorporating environmental awareness training (including ARD issues) into the induction training program for all mine staff
  • Ensuring that environmental reporting becomes a standard agenda item at relevant operations and corporate meetings
  • Developing clear action triggers for all key ARD monitoring points to ensure proactive action
  • Including personnel from the corporate environment department who will have the responsibility to ensure that proper consideration is given to the life-cycle environmental risks into project development teams
  • Conducting post-incident investigation of incidents where environmental and ARD monitoring criteria are exceeded or when a noncompliance incident is reported to determine the cause of the incident and define and implement corrective measures to prevent a repeated occurrence.

The evaluation, design, and operating cycle depicted in Figure 9-6 is typically repeated during each of the mine life stages as a continuous process, as illustrated in Figure 9-7. Such a total life cycle approach is clearly applicable for green field projects and will proceed through all the mine life cycle stages. However, the evaluation, design, and operating cycle can also be applied to projects that are not further developed after the exploration stage, existing operations, and closed mines.

Figure 9-6: The Cycle for Developing and Implementing ARD Management Plans in each Life Cycle Stage
Image:CycleforDevelopingandImplementingARDManagementPlans.gif



Figure 9-7: Mine Life Cycle Development and Implementation of ARD Management Plans
Image:MineLifeCycleDevelopmentandImplementationofARD.gif


In the case of advanced exploration projects that are not further developed, at least one cycle of the design process presented in Figure 9-7 would be applied. For such projects, an ARD management plan can be developed and implemented for exploration. When the decision is made to end the exploration activities without further mine development, a closure plan should be developed and implemented. In that case, the project proceeds directly from exploration to closure.

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9.3.2 Management System Roles and Responsibilities

The corporate staff should play an important role in ensuring the development and integration of the ARD management plan into the mine site’s EMS. That role includes auditing the implementation and success of the EMS. Corporate staff can assist with strategic planning in the EMS and with consistent environmental performance when key mine operating staff change.

While precise company structures differ between companies, key features and components of an effective management structure for ARD plans might include the following:

  • A senior level person who takes responsibility for the corporate environmental (and ARD) management system including policies and guidelines, and may be a key resource for technical information on ARD. The corporate environment department oversees the company’s overall environmental programs, including ARD management standards and guidance, and prepares status reports for the company executive and may assist in compiling the business units report to the board of directors.
  • The mine site’s general manager has ultimate responsibility for the implementation of the ARD management plan and integrating the responsibilities into the relevant operations departments.
  • The chief geologist, who is responsible for the geological block model (and ARD block model where needed).
  • The mine and mill managers and superintendents are typically responsible for implementing the ARD management plan because the plan must be integrated into mine operational activities.
  • The site’s environment department should primarily review, audit, and monitor the ARD management plan, ensuring that the plan is being followed by mine operations’ functional groups. This could include evaluating field data and performance against the objectives of the plan, interpreting the data, and linking data from the mine or the mill (e.g., comparing mine dispatch data on segregation of waste rock against seep survey data from the dump or reviewing sulphate and metal concentrations in tailing pond or waste dump seepage). Where required, the environment department should have an appropriately qualified scientist or engineer with practical experience across a wide range of relevant disciplines to ensure that the ARD management issues relevant to the mining and process operation are understood.

The bullet items above are examples of possible roles and responsibilities and illustrate the range of activities and multidisciplinary aspects of ARD management plan implementation. Mines will employ different organizational structures based on specific needs and personnel.

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9.4 Long-Term Considerations

An ARD management plan should provide for the sustained existence and performance of the structures that are required to achieve long-term prevention and mitigation of ARD. In this Section 9.4, some of these long-term issues and effects are presented that should be considered in the development of ARD management plans to manage present and future impacts.

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9.4.1 Design Horizon

The robustness of the technology selected to address ARD issues determines, to a great extent, the long-term success of ARD prevention and mitigation. The cost of more robust technologies should be compared to the costs of planning and maintenance for very long periods of time.

Regardless, there is a need to make a rational and practical decision on the service life for which management measures are designed and during the time period they need to be assessed. While there are no consistent or universal regulatory guidelines, many designs and cost analyses are conducted for a time horizon of 100 years. From a cost perspective, the financial provision that caters for events during the next 100 years is very similar to a financial provision that caters for longer periods of time, when measured in net present value (NPV) terms, depending on the discount rate used in the calculations. The various investment uncertainties will often have a bigger impact on the NPV than a timeline that extends beyond 100 years. However, many companies and regulatory agencies are examining other methods of assessing the long-term cost of ARD management beyond NPV calculations.

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9.4.2 Long-Term Resources

There are various mechanisms that are used throughout the world to manage post-closure monitoring and maintenance requirements across the spectrum of closure activities and ARD management is only one component of the overall closure plan. The key post-closure activities related specifically to ARD can range from a relatively active site presence (and cost) for long-term operation of water management and water treatment to a relatively minimal requirement of periodic monitoring and maintenance of structures to control water levels and maintain flooded conditions. In many cases, given thorough site characterization and application of the “design for closure” principle, only a performance monitoring period of two to ten years may be required.

The operating model for this post-closure maintenance can vary as follows:

  • Continued operation post closure by the mining company (This model is typically seen in larger mining companies that continue to have operating sites elsewhere combined with the financial wherewithal to ensure funding. Within this model, the site might be managed primarily by third-party contractors or by company employees.)
  • Third-party management of the site, funded either by the former owner/operator or by a commercial arrangement with the third party
  • Completion of decommissioning activities, post-closure management and monitoring of the site by the owner/operator for some time period during the evaluation of the performance of the closure measures, followed by turnover to a government or regulatory authority under a regulatory release for continuing monitoring or maintenance, as required
  • Sale of the property to a new owner/operator for subsequent reopening (This type of transaction will require some agreement on the transfer or retention of liabilities for the former owner. The contractual and regulatory acceptance of the transfer of liabilities will typically depend on the confidence that is placed in the evaluation of post-closure liabilities.)

With respect to the staffing or human resources for closure, there are again a variety of options that are typically considered within a closure plan, ranging from staffing from remaining operating staff, use of contractors and consultants, to developing local business opportunities to operate the post-closure site.

A critical element in the definition of the post-closure management model is the quantification of the time period for active site management and the associated costs.

There are a number of different international guidelines on closure funding and many countries are still in the process of developing legislation and guidance on these closure funding mechanisms. It is beyond the scope of this document to discuss the mechanisms in detail; however, the following guiding principles are becoming standard for closure planning and financial assurance:

  • Define the time period for post-closure management based on predictive modeling, monitoring, assessment and prediction model calibration and validation, and then negotiation with the relevant regulatory authorities
  • Define the specific activities and associated costs, using a risk-based approach (The risk based evaluation considers uncertainty in predictions and performance of ARD management measures and expected value [or range] of costs.)
  • Define the performance criteria and triggers for action (These in turn typically trigger a re-evaluation of the closure cost modelling.)
  • Develop a financial model to quantify the provision required over time, considering the uncertainties of both the site requirements and the potential investment risks and uncertainties
  • Define the financial assurance mechanism either internally to the company or externally to ensure that the funds are available as required and when needed (Typically, this will include some form of audit of the financial reserve. Again, guidance varies by jurisdiction or country regarding financial tests to select the appropriate mechanism.)
  • Link the cycle of planning, monitoring, auditing, and corrective action within the ARD management and closure plans to update the financial modelling

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9.4.3 Information/Institutional Knowledge Retention

A significant issue in implementing mine decommissioning and post-closure activities is that key information, previously obtained and recorded by mine operating staff, might be discarded or lost at the time of the cessation of mine production. Electronic storage can greatly facilitate future retrieval, but to be effective, all relevant information must be in, or be converted to, electronic format.

The EMS implemented by the mine should make specific provision for the identification, recording and cataloguing, electronic storage (where possible), and preservation of all data relevant to ARD management and assessment (e.g., see ISO 14001 standard [ISO, 2004]).

The type of data that should be retained, include the following:

  • Exploration logs and data
  • Detailed mining plans and survey data for actual mining operations
  • Production records for mine and beneficiation plant
  • Records on waste and residues (e.g., treatment sludges) production for mine and beneficiation plant
  • Depositional history and construction details for all wastes
  • Records on backfill materials placed back into underground and open pit mine workings
  • All environmental monitoring data (e.g., air, water levels, water flows, water quality, soils, dust, ecological, geochemical, and waste characterization)
  • Records on environmental noncompliances and stakeholder complaints
  • All specialist environmental and ARD reports produced by or for the mine

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9.4.4 Changing Standards/Stakeholder Needs and Expectations

Stakeholders (regulators and communities) expectations change with the stage of mine development. What may be considered appropriate for an ARD management plan differs for new, operating, and closed mines. The expectations of the stakeholders, who will be the decision makers at the time of mine closure, must be provided for in the development of an ARD management plan including, if required, the post-closure custodianship of the site.

Regulatory conditions continue to become more stringent with time and the bar for minimum compliance is therefore often raised (or “the goal posts are shifted”). A mine that develops and implements an ARD management plan based on an objective and scientific assessment of all its risks from a sustainable development perspective, even when it is not required by current regulatory requirements, will have the inherent capacity to meet changes in the regulatory and community environment. This resilience is especially valuable for mining projects that have a long life, measured in decades, where the issues of tightening and more stringent regulatory controls over the mine life cycle are a reality. This resilience also allows the mine to plan for the future.

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9.5 References

Department of Industry, Tourism and Resources (DITR), 2006-2008. Leading Practice Sustainable Development Program for the Mining Industry. http://www.ret.gov.au/resources/Pages/Publications.aspx.
Dushnisky, K., and S.G. Vick, 1994. Evaluating risk to the environment from mining using failure modes and effects analysis. In: C.D. Shackelford, P.P. Nelson and M.J.S. Roth (Eds.), Uncertainty in the Geologic Environment: From Theory to Practice, ASCE, 2:848-865.
Gibson, R.B., 2005. Sustainability Assessment. Earthscan Publications.
Haimes, Y.Y., 2004. Risk Modeling, Assessment, and Management, 2nd Edition. John Wiley and Sons, Hoboken, NJ.
ISO 14001, 2004. Environmental management systems - requirements with guidance for use. International Organization of Standards.
Robertson, A. MacG., and S. Shaw, 2004. Use of the Multiple Accounts Analysis Process for Sustainability Optimization. In: Proceedings of the SME Annual Meeting, February 23-25, Denver, CO.
Shaw, S.C., Robertson, A. MacG., Maehl, W.C., Kuipers, J., and S. Haight, 2001. Review of the Multiple Accounts Analysis Alternatives Evaluation Process Completed for the Reclamation of the Zortman and Landusky Mine Sites. National Association of Abandoned Mine Lands Annual Conference, August 19-22, Athens, OH.

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List of Tables

Table 9-1: Mine Life Cycle Considerations for the Development of ARD Management Plans
Table 9-2: Technical Disciplines Involved in the Development of an ARD Management Plan
Table 9-3: FMEA Outcomes Combining Likelihood of Failure and Consequences
Table 9-4: Monitoring and Performance Assessment of Success

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List of Figures

Figure 9-1: Flowchart for Performance Assessment and Management Review
Figure 9-2: Hierarchy of Management Tools
Figure 9-3: Open Pit Bench Plan Developed During the Feasibility Phase of a Mine Project
Figure 9-4: Overall Segregation of Various Waste Rock Units Based on their ARD Potential and Physical Characteristics
Figure 9-5: Typical Environmental Management Model
Figure 9-6: The Cycle for Developing and Implementing ARD Management Plans in each Life Cycle Stage
Figure 9-7: Mine Life Cycle Development and Implementation of ARD Management Plans

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