Failure Mode Effects Criticality Analysis (FMECA) - Giant Mine ...

Prepared by:AECOM17007 – 107th Avenue 780 486 7000 telEdmonton, AB, Canada T5S 1G3 780 486 7070 faxwww.aecom.com

Golder Associates Ltd.500, 4260 Still Creek Drive 604 296 4200 telBurnaby, BC, Canada V5C 6C6 604 298 5253 faxwww.golder.com

Project Number:60198153

Date:June, 2011

Public Works and Government Services Canada

Failure Mode Effects Criticality Analysis(FMECA) - Giant Mine Remediation –Mackenzie Valley Environmental ImpactReview Board – Information Request 12Response

AECOM Public Works and Government Services Canada Failure Mode Effects Criticality Analysis (FMECA)-Giant Mine Remediation – Mackenzie ValleyEnvironmental Impact Review Board – InformationRequest 12 Response

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The information, data, recommendations and conclusions contained in the Report (collectively, the “Information”):

is subject to the scope, schedule, and other constraints and limitations in the Agreement and thequalifications contained in the Report (the “Limitations”)represents Consultant’s professional judgement in light of the Limitations and industry standards for thepreparation of similar reportsmay be based on information provided to Consultant which has not been independently verifiedhas not been updated since the date of issuance of the Report and its accuracy is limited to the timeperiod and circumstances in which it was collected, processed, made or issuedmust be read as a whole and sections thereof should not be read out of such contextwas prepared for the specific purposes described in the Report and the Agreementin the case of subsurface, environmental or geotechnical conditions, may be based on limited testing andon the assumption that such conditions are uniform and not variable either geographically or over time

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Consultant agrees that the Report represents its professional judgement as described above and that theInformation has been prepared for the specific purpose and use described in the Report and the Agreement, butConsultant makes no other representations, or any guarantees or warranties whatsoever, whether express orimplied, with respect to the Report, the Information or any part thereof.

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AECOM Public Works and Government Services Canada Failure Mode Effects Criticality Analysis (FMECA)-Giant Mine Remediation - Giant Mine Remediation –Mackenzie Valley Environmental Impact ReviewBoard – Information Request 12 Response


Table of Contents

Statement of Qualifications and LimitationsDistribution List

page

1. Introduction .................................................................................................................................. 11.1 Scope ............................................................................................................................................. 11.2 Information Request (IR) ................................................................................................................. 11.3 Workshops ..................................................................................................................................... 1

2. Risk Assessment Framework ..................................................................................................... 32.1 Risk Timeline .................................................................................................................................. 3

2.1.1 Short Term ......................................................................................................................... 32.1.2 Long Term.......................................................................................................................... 3

2.2 Assumptions ................................................................................................................................... 32.2.1 Permits............................................................................................................................... 32.2.2 Funding .............................................................................................................................. 32.2.3 Care and Maintenance ....................................................................................................... 32.2.4 Worker Health and Safety................................................................................................... 4

2.3 Definitions....................................................................................................................................... 42.3.1 Initializing Event / Cause .................................................................................................... 42.3.2 Accident ............................................................................................................................. 42.3.3 Malfunction......................................................................................................................... 42.3.4 Credible Event.................................................................................................................... 42.3.5 Failure Scenario ................................................................................................................. 42.3.6 Cascading Events Scenario ................................................................................................ 42.3.7 Multiple Cause Scenario ..................................................................................................... 52.3.8 System Failure ................................................................................................................... 52.3.9 Component Failure ............................................................................................................. 52.3.10 Mine Water Treatment Plant (Mine WTP) and Effluent Treatment Plant (ETP) .................... 5

2.4 Initiating Events at Giant Mine ......................................................................................................... 52.5 Systems and Components at Giant Mine ........................................................................................ 52.6 Risk Assessment Methods .............................................................................................................. 6

2.6.1 Failure Scenario Analysis (FSA) ......................................................................................... 72.6.1.1 Description of FSA ............................................................................................ 72.6.1.2 Process ............................................................................................................ 72.6.1.3 Failure Scenario Tree ....................................................................................... 7

2.6.2 Failure Mode Effects Criticality Analysis (FMECA) .............................................................. 82.6.2.1 Description of FMECA ...................................................................................... 82.6.2.2 Risk Matrix ........................................................................................................ 92.6.2.3 FMECA Table ................................................................................................. 11

3. Risk Assessment Results.......................................................................................................... 133.1 Identified Risks for the Giant Mine Remediation Project ................................................................ 13

3.1.1 Short and Long Term FSA ................................................................................................ 133.2 Cascading Events Scenarios ........................................................................................................ 133.3 Multiple Cause Scenarios ............................................................................................................. 133.4 Likelihood and Consequence Severity of Identified Failure Scenarios ............................................ 14

3.4.1 Short and Long Term FMECA .......................................................................................... 14

AECOM Public Works and Government Services Canada Failure Mode Effects Criticality Analysis (FMECA)-Giant Mine Remediation - Giant Mine Remediation –Mackenzie Valley Environmental Impact ReviewBoard – Information Request 12 Response


3.5 Summary ...................................................................................................................................... 14

4. References ................................................................................................................................. 16

List of Figures

Figure 1: Initiating Event Failure Tree ....................................................................................................................... 7Figure 2: Component Failure Tree ........................................................................................................................... 8Figure 3: Risk Matrix Format .................................................................................................................................. 10Figure 4: FMECA Table Format ............................................................................................................................. 12

Appendices

Appendix A – Failure Scenario Analysis (FSA)Appendix B – Failure Mode Effects Criticality Analysis (FMECA)Appendix C – Cascading Event ScenariosAppendix D – Multiple Cause ScenariosAppendix E – List of Participants for Workshops


AECOM Risk Report.Docx 1

1. IntroductionGiant Mine is an abandoned gold mine which is currently under the care and maintenance of Indian and NorthernAffairs Canada (INAC) while preparations are made to implement the long term remediation plan for the site. TheGiant Mine Remediation project Developer’s Assessment Report (DAR) (SRK, 2010) is currently under review by theMackenzie Valley Environmental Impact Review Board (MVEIRB). The DAR outlines the overall remediation plan forall aspects of the site. In addition, the preliminary design is currently being developed to expand on the overall planoutlined in the DAR. The DAR includes Section 10 which assesses risks associated with the remedial plan outlinedin the DAR for the first 25 years of implementation.

1.1 Scope

The scope of this report is to address requests for information which were raised during the MVEIRB review of theGiant Mine Remediation plan outlined in the DAR. The purpose of this report is to address the Information Requests(IR) on the subject of risk by expanding on the risk assessment completed as part of the DAR development andcompleting a Failure Mode Effects Criticality Analysis (FMECA). AECOM Canada Ltd. (AECOM) and GolderAssociates Ltd. (Golder) developed this report, which is a summary and compilation of risks identified and assessedin workshops by a number of participants.

1.2 Information Request (IR)

Information Request #12 was developed by the MVEIRB Review Board and includes 5 questions which are listedbelow.

1. Please identify risks for the life of the project, beyond those occurring during initial development activities.2. Please identify scenarios for events in short and long-term which could cause multiple failures of

components of the project.3. Please evaluate probabilities and severities and consequences (including costs) resulting from those

scenarios.4. Please describe how failures of individual components would affect the larger system they are part of.5. Please describe probabilities, severities and consequences (including costs) for the events discussed in

section 10 (of the DAR) plus any additional long term risks identified (see point 1 above).

This report supports responses to the above questions.

1.3 Workshops

Three workshops were held for the purpose of identifying and assessing risks. The following was the overall purposeof the workshops.

Develop sequences of events over the short and long term that may lead to component failures and consequentiallosses. Identify the causes of key component failure. Describe or develop mitigation measures or safeguardsincluded in the remedial design and management system to manage, mitigate or prevent these failures.

There were three workshops held to achieve the overall purpose. The workshop details are listed below including alist of participating agencies. A detailed list of those that attended on behalf of each agency is attached in AppendixE.



Workshop 1: March 22 to 24, 2011 in Vancouver Participants: INAC, PWGSC, Department of Justice (DOJ), Golder, and AECOM.

Workshop 2: April 4 to 6, 2011 in Vancouver Participants: INAC, PWGSC, DOJ, Golder, AECOM, and SRK Consulting (SRK).

Workshop 3: May 30 and 31, 2011 in Edmonton Participants: INAC (including technical advisor, Brodie Consulting), PWGSC, Golder, and AECOM

The first workshop included a brainstorming session to identify events and major component failures. Participantsexpanded on the consequences of each of the events identified and developed the first draft of the Failure ScenarioAnalysis (FSA). Components which could result in major system failure were also identified in the FSA format.Failure scenarios were developed through trees indentifying the sequence of events in the scenario. These failurescenarios were used in the second workshop to analyze the risk associated with these scenarios. The thirdworkshop reviewed these risks as it applied to the short term and long term scope of the Giant Mine Project. Riskmitigating measures were included in the risk estimates, and where appropriate, additional measures wererecommended and the risk was re-assessed.



2. Risk Assessment Framework2.1 Risk Timeline

2.1.1 Short Term

Short term risks, as defined for the purpose of this risk assessment, are risks which occur during the implementationof the Giant Mine Remediation project. This timeline begins on day one of the remediation contract for that specificsystem or component and ends when steady state has been achieved, for an approximate duration of 25 years. TheGiant Mine Remediation project will involve a series of remediation contracts which may not occur simultaneously,therefore the short term risk timeline may vary from one system or component to another.

For example, the short term timeline for the existing structure demolition would begin on day one of the demolitioncontract and would be complete once all the existing structures are decontaminated, demolished and the wastesorted, transported and disposed of. The short term timeline for structural demolition may be less than the general25 year timeline, depending on the sequencing of demolition.

2.1.2 Long Term

The risk of events which could occur after steady state is achieved is defined as long term for the purpose of thisassessment. The assumed endpoint of this timeline is 100 years, beginning after steady state is achieved. Theidentification and assessment of these risks is limited to what the assessment team can envision for the next 100years based on the current remediation plan. This 100 year period is the time in which the remedial components areexpected to function within specified parameters with ongoing maintenance. However, this time frame does includelow probability events, such as a 1 in 500 year rainfall event. If the remediation plan is changed, or at some futurepoint a new remediation technology is implemented, the long term risks would require reassessment.

2.2 Assumptions

Risks were identified and assessed within the scope of this report in the context of the following generalassumptions. Any specific assumptions for a particular failure mode or scenario are included in Section 3.4 of thisreport.

2.2.1 Permits

All required permits or other approvals are assumed to have been attained prior to the start of projectimplementation. Delays as a result of permit or approval application have not been included into the short termtimeline for the risks identified and assessed. Risks associated with permits and approvals have not been included inthe scope of this assessment.

2.2.2 Funding

Funding for the remediation is assumed to be in place prior to project implementation. Delays in the project and therisks to the project as a result of funding delays have not been assessed, except as a total project failure scenario inthe assessment of institutional failures.

2.2.3 Care and Maintenance

The scope of this risk assessment does not include the care and maintenance period and the risks which couldoccur before the start of the short term risk timeline. It is assumed that care and maintenance will continue until



project implementation and that the remediation contracts will overlap with the care and maintenance contract andall systems would be maintained as per current standards until the implementation starts.

2.2.4 Worker Health and Safety

Worker health and safety is not included in this assessment. Worker health and safety will change based on themethods for completing the work, which the remediation contractor will decide. The assumption is that worker healthand safety will be assessed once the detailed remediation design is completed and all tasks would be performedwith appropriate health and safety plans by staff with appropriate training, in compliance with the applicableregulations (eg. NWT Mine Health & Safety Act).

2.3 Definitions

The following terms are defined to closely align with the Developer’s Assessment Report (DAR) (SRK, 2010) and toremain consistent with language used in the IR. These definitions will be used to describe the possible risks tomaintain consistency throughout this assessment.

2.3.1 Initializing Event / Cause

An initializing event or cause is the root of all failure scenarios and is the cause of system or componentfailure. An initiating event can lead to either an accident or malfunction and includes natural events,technological causes, or human error. A list of major initiating events or causes assessed for the Giant MineRemediation project is included in Section 2.4 of this report.

2.3.2 Accident

An accident is an unplanned event which leads to system or component failure. An accident could be aresult of a specific initiating event or cause. Examples of accidents include extreme weather, human errorand traffic accidents. Prevention measures could be implemented to decrease the likelihood of an accidentand mitigating measures could be implemented to reduce the effects of an accident.

2.3.3 Malfunction

A malfunction is the failure of a system, component or sub-component (eg. equipment) to function in amanner for which it was intended. A malfunction can result from an initiating event or cause as definedabove.

2.3.4 Credible Event

A reasonable probability of occurrence based on professional judgement in the context of project-specificconditions.

2.3.5 Failure Scenario

A failure scenario is a specific sequence of events starting with an initiating event or cause which leads tosystem or component failure and corresponding impacts from that failure.

2.3.6 Cascading Events Scenario

A cascading events scenario starts with one initiating event or cause which causes the failure of multiplesystems or components.



2.3.7 Multiple Cause Scenario

A multiple cause scenario starts with two or more unrelated initiating events or causes which occursimultaneously and cause the failure of systems or components.

2.3.8 System Failure

A system failure within the Giant Mine Remediation project is a major design or operating system that can nolonger perform its function as required. System failures have the largest impact on the integrity of the projectand are major remediation design elements. Each system has the potential to fail through a variety ofinitiating events or causes. A list of systems assessed for the Giant Mine Project is included in Section 2.5 ofthis report.

2.3.9 Component Failure

A component failure within the Giant Mine Remediation project occurs when one or more parts orcomponents of a system can no longer perform its function as required. A list of all components assessed forthe Giant Mine Project is included in Section 2.5 of this report.

2.3.10 Mine Water Treatment Plant (Mine WTP) and Effluent Treatment Plant (ETP)

The Effluent Treatment Plant (ETP) is the current treatment plant at the Giant Mine Site. This treatment plantis operational only seasonally. In the short term the ETP will be operational while the new Mine WaterTreatment Plant (Mine WTP) is being constructed. The Mine WTP will be operational on a full time basis inthe long term as part of the Water Management System.

2.4 Initiating Events at Giant Mine

The following have been identified as the major initiating events (accidents) or causes of failure scenarios at theGiant Mine Remediation project. These initiating events may cause other accidents or malfunctions, which in turnimpact systems and components of the project. .

1. Environment (Extreme Weather)2. Flood3. Forest Fire4. Power Failure5. Seismic6. Climate Change

2.5 Systems and Components at Giant Mine

The following have been identified as the seven major systems and associated components/subcomponents of theGiant Mine Remediation project.

1. Water Management SystemA. Water StorageB. PipingC. Existing Effluent Treatment Plant (ETP)

i. Settling/Polishing PondD. Mine Water Treatment Plant (eg. Chemical supply for operation)



E. DiffuserF. PumpsG. Bay Assimilation Capacity (eg. Loss of capacity in receiving environment)

2. Underground SystemA. Arsenic Chambers/StopesB. Non-arsenic Chambers/StopesC. Crown Pillars/SillsD. Backfill

3. Baker Creek SystemA. BanksB. Creek Beds (Stability)C. Stream Channel

i. Ice dammingii. Blockages (Beaver Dams)

4. Freeze SystemA. Freeze Implementation

i. Freeze Plantii. Passive Cooling Infrastructure Component

B. Drill HolesC. Frozen ShellD. Frozen Block

i. Passive Freezing (Monitoring System)E. Intentional Thaw

5. Surface SystemA. Tailings

i. Coverii. Damiii. Spillways

B. Open Pits/ Surface Openingsi. Site Security

C. Highway

6. Buildings (Short Term Only)A. RoasterB. MillC. Stack

7. Institutional System (Management of the Project)

2.6 Risk Assessment Methods

The following sections describe the methods used to assess risk over the short and long term that have the potentialto lead to system failure, component failures and consequential losses. These methods identify key initiating eventsor causes and identify the potential impacts of system or component failures. Failure scenarios for each system arethen assessed for likelihood and severity of impact to public health, the environment and cost. A combination of the



likelihood and severity of impact is used to categorize the risk associated with that particular failure scenario. Whereappropriate, a description of possible mitigation measures is included and a reassessment of the risk is completed.

2.6.1 Failure Scenario Analysis (FSA)

2.6.1.1 Description of FSA

As described in Canadian Standards Association’s Risk Analysis Requirements and Guidelines (CSA, 1991), FailureScenario Analysis (FSA) is a method of identifying and organizing conditions and/or factors that can contribute to aspecific undesired event. In this method, there is one initiating event (the root) with connecting accidents ormalfunctions that lead to system or component failures that are caused by the root event. Failure Scenario Analysis(FSA) allows for a systematic analysis of how a variety of factors relate directly to the initiating event.

2.6.1.2 Process

The following steps outline the process of the FSA method.1. Defining the undesired event to study;2. Obtaining an understanding of the system;3. Constructing a tree linking the scenario events;4. Evaluating the tree; and5. Identifying failure scenario controls (prevention and/or mitigating controls)..

The FSA process was completed at the first risk workshop, as described in Section 1.3. Participants of this workshopidentified the initiating events as well as the major systems and components failures of the Giant Mine Remediationproject.

2.6.1.3 Failure Scenario Tree

One of the advantages of using an FSA approach is the ability to clearly illustrate the sequence of events that cantake place or are required to take place for a failure to occur. This method effectively illustrates how resistant asystem is to single or multiple initiating events. Figure 1 displays an example of the layout of an initiating eventfailure tree.

InitiatingEvents

Malfunction

Failure 1 SubsequentFailure 1

Failure 2

Accident Failure 3

Accident Failure 4

Figure 1: Initiating Event Failure Tree



This method distinguishes time frames of the malfunction/accident being analyzed. The same malfunction can havedifferent results depending on whether it has occurred in the short term period of the project or the long term. Todecipher between these, pink events occur in the short term, blue events occur in the long term, and orange eventsoccur in both short and long term.

This method of analysis was also used to identify various credible initiating events and malfunctions/accidents thatcan lead to one of the components of the Giant Mine to fail. Figure 2 illustrates this layout of a component failuretree. The advantage to using this layout is it provides insight to all the different ways the major components can fail.

2.6.2 Failure Mode Effects Criticality Analysis (FMECA)

This section is an adaptation of Golder Associates, Introduction to the Systems FMECA Method for RiskAssessment. (Golder, 2011)

2.6.2.1 Description of FMECA

Overview

The Systems Failure Modes and Effects Criticality Analysis (FMECA) method is an adaptation of the FMEA methodoriginally developed to assess the detailed risk associated with parts and components of equipment. Thisadaptation includes studying large systems, rather than small components, identifying risk mitigation measures,estimating and ranking the risk using the risk matrix and documenting the results in the FMECA tables. TheSystems FMECA method covers all of the standard risk assessment steps.

The Systems FMECA method allows teams of experienced personnel to evaluate large systems by identifyinganalysis objectives, analysis processes, and failure modes. Credible failure modes and their associatedconsequences were first identified using an assessment protocol and the knowledge base of the risk assessmentteam. Controls and/or design elements to mitigate risk were also identified. Public safety, environment, and costrisk (as defined in the objectives) was estimated for each failure mode and associated consequence using a riskmatrix approach.

ComponentFailure

Failure 1

MalfunctionInitiating Event1

Initiating Event2

AccidentInitiating Event3

Failure 2AccidentInitiating Event4

Figure 2: Component Failure Tree



Team Workshop

The Systems FMECA method was based on a team of experienced personnel assessing risks in a systematicworkshop process. The team for Giant Mine included AECOM, Golder, SRK, PWGSC, INAC, and DOJrepresentatives as detailed in Section 1.3 of this report. The experience of team members, along with keydocuments, provided the knowledge base and the workshop format provided a method to build synergies given thewide range of experience and knowledge.

Analysis

The first step in risk analysis involved defining the objectives and context for the assessment. Objectives focused onthe assessment of specific impacts that may include any number of risks to the public, the environment, or cost. Thescope of the analysis defined the system and how it can be divided into principal units to be analyzed separately(and then as a complete system).

A Systems FMECA is a comprehensive process designed to identify potential significant and credible “failure modes”associated with the system being assessed (e.g., an operating facility assessed unit by unit). The “failure mode”describes how a system may fail and includes all possible causes ranging from natural events, such as earthquakesto equipment failures, operator errors, and management system deficiencies. Potential public safety, environment,or cost “effects”, as defined in the study objectives, are also identified for each failure mode. For example,environmental “effects” may be measured in terms of environmental clean-up costs following a release from afacility. A series of events usually needs to occur before a “failure mode” results in an “effect,” and therefore thecomplete series of events or failure scenario is assessed. Following the identification of this series of events, therisk or “criticality” is estimated using a Risk Matrix approach described in Section 2.6.2.2.

2.6.2.2 Risk Matrix

For each of the significant failure modes and corresponding consequences (failure scenarios) identified in theSystems FMECA, a measure of the associated risk was estimated using risk matrix methodology. A risk matrix iscomprised of one index representing the measure of frequency and another index representing the measure ofconsequence severity. When a failure mode and consequence scenario was identified, the associated risk wasestimated by locating it within the risk matrix.



A number of attributes of the risk matrix are illustrated in Figure 3.

CATEGORYCONSEQUENCE SEVERITY

A) Low B) Minor C) Moderate D) Major E) Critical

I) Public Safety

Low-level short-term subjectivesymptoms/ No

measurablephysical effect/ Nomedical treatment

Objective butreversible

disability/impairmentand/or medical

treatment injuriesrequiring

hospitalization

Moderateirreversibledisability or

impairment toone or more

people

Single fatalityand /or severe

irreversibledisability or

impairment toone or more

people

Multiple fatalities

II) Environment No impactMinor localized orshort-term impacts

Impact on valuedecosystemcomponent

Impact on valuedecosystem

component andmedium-termimpairment of

ecosystemfunction

Serious long termimpairment of

ecosystem

function

III) Cost ($) <100,000 100,000-1M 1.0M-10M 10M-50M >50M

LIKELIHOOD

Index Event/Years

1More than onceevery 5 years

2Once every 15

years

3Once every 30

years

4Once every 100

years

5Once every 1000

years

Likelihood Index

As shown in Figure 3, the likelihood or frequency index on the left of the matrix ranges from a “1” (Frequent) to a “5”(Infrequent) event and is more formally defined in terms of frequency with an events/year value. The index is dividedinto orders of magnitude with the expectation that the knowledge base of the team and the historical industryperformance record will be sufficient to estimate the level of risk to this accuracy.

Consequence Categories

In this matrix, 3 categories of consequences have been assessed for the Giant Mine Remediation project; publicsafety, environment, and cost.

Figure 3: Risk Matrix Format

Increasing Risk



The severity of effects for each category of consequence is defined by an index ranging from “Low” to “Critical.”These indices are detailed with the definitions used for this risk assessment workshop. In total, there are threeseparate risk matrices shown in Figure 3 (one for each consequence category), and each failure scenario would belocated in one or more of these three matrices as appropriate.

Risk Evaluation

Risk evaluations were completed following the identification of risk scenarios and measurement of consequences.The evaluation of risk requires determining the acceptability of risk as defined through the different locations (or riskvalues) within the risk matrix developed for the risk assessment.

The criteria for evaluating risks were developed for the risk management program and were useful for comparingrisks, such as those among different operations, or for prioritizing risks. The risk matrix shown in Figure 3 wasdivided into five groups representing the criteria for managing risks. These groups were color-coded from Green(lowest risk) to Yellow to Orange to Red to Dark Red (highest risk).

The high priority risk level (color-coded dark red and red) may be associated with a management action to “ReduceRisk.” Action steps may involve more detailed study to improve the risk estimate and determine if it is actually lowerthan estimated. In some cases, all mitigation options may prove to be uneconomic and senior management maydecide to accept the risk but actively manage it.

The intermediate risk levels (color-coded orange and yellow) may be associated with various management actions to“Reduce Risk as Appropriate” and involve balancing the cost of mitigating risk with the benefits received. Actionsteps may again involve further study to improve the risk estimate. They may also include prioritizing the applicationof resources according to the identified risks and implementing measures to decrease risk either by decreasingfrequency, consequences, or a combination of the two. The risk matrix illustrates this concept of reducing risk.Different cost implications are often associated with the choice of decreasing frequency, consequences, or acombination of the two.

The lowest risk level (color-coded green) may be associated with the management action to “Monitor and ControlRisk” and involve accepting the risk as long as it is both monitored and controlled to ensure it does not creep up tothe next level.

2.6.2.3 FMECA Table

Results from the Systems FMECA are documented in an FMECA Table that includes the following information: System, unit description Component / Subcomponent Risk Issue / Failure Event / Causes Potential Consequences (one or more for each failure mode) Risk Estimate Planned Mitigation / Controls / Management Measures Evaluation Residual Risk Estimate according to frequency and consequence location in each risk matrix



A schematic of the FMECA Table format used, with an example for one failure scenario, is presented in Figure 4below.

Figure 4: FMECA Table Format

As shown, the above table documents a description of the failure scenario including existing safeguards, an estimateof the residual risk for all relevant categories, and any further comments or background on uncertainty associatedwith the assessment. Where appropriate, a follow up risk rating classification was completed after mitigatingmeasures were assessed. Uncertainty in the assessment (or risk rating) as a result of knowledge base, randomprocess, etc., are described qualitatively through the confidence index column (high, medium, or low).

Pub

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Envi

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ent

Cos

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Pub

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afet

y

Envi

ronm

ent

Cos

t

SS-4 Ditches Accident: Flooding Extreme rainfall Sediment discharge, erosion andsediment release to Baker Creek.

3 A C B Ditches will be upgraded to finaldesign standard including rip-rapcover treatment on erodible finematerial.

Erosion and sediment controlduring construction will reducethe risk of sediment releases.

4 A C B High

EVENT/CAUSES

Short Term

PLANNEDMITIGATION/CONTROLS/

MANAGEMENT MEASURES

LIK

ELIH

OO

D

SUBCOMPONENT

CONSEQUENCESEVERITY

POTENTIAL CONSEQUENCES ConfidenceEstimate

EVALUATION

LIK

ELIH

OO

D

CONSEQUENCESEVERITY

RISK ISSUE /FAILURE ID COMPONENT



3. Risk Assessment Results3.1 Identified Risks for the Giant Mine Remediation Project

3.1.1 Short and Long Term FSA

The Failure Scenario Trees developed in the first workshop are included in Appendix A. These trees summarizecredible failure scenarios relevant to the Giant Mine Remediation project. They identify both the effects of initiatingevents on the overall project as well as the impact component failure has on overall systems of Giant Mine.

These Failure Scenario Trees address Question 1 of IR 12, as they identify the risk events for this project in both theshort and long term. The component failure trees address Question 4 of IR 12, as they identify how a componentfailure can affect an overall system of the Giant Mine project.

These trees were used as a basis to develop the failure scenarios, cascading event scenarios, and multiple causescenarios assessed in the FMECA tables.

3.2 Cascading Events Scenarios

Cascading events refer to the series of accidents and malfunctions that may occur because of one initiating event.One malfunction may cause another series of malfunctions which in turn can cause other undesirable results. Thetime period of occurrence (during the short or long term) also has an influence on end results.

These cascading events scenarios for both the short and long term time frames are summarized in the tablesincluded in Appendix C.

The information in the tables addresses Question 2 of IR 12, as they identify multiple failure scenarios for bothsystem and components at Giant Mine in both the short and long term.

3.3 Multiple Cause Scenarios

Multiple cause scenarios are specific fault scenarios which include two or more initiating events occurringsimultaneously. These fault scenarios have a low likelihood of occurring because the likelihood of two unrelatedcauses happening simultaneously is lower than that of the causes happening separately.

The identified multiple cause scenarios, included in Appendix D, focus on the freeze system and the watermanagement system. These are generally the systems which are associated with higher ratings for risk and willcontinue to operate in the long term.

The information in these tables addresses Question 2 of IR 12, as they identify additional multiple failure scenarios inthe short and long term for both system and components.

The cascading events and multiple cause scenarios include a link in the tables to the appropriate FMECA riskassessment for that scenario.



3.4 Likelihood and Consequence Severity of Identified Failure Scenarios

3.4.1 Short and Long Term FMECA

The information in the FMECA tables addresses Questions 3 and 5 of IR 12. This assessment was completed for thefailure scenarios identified by the following methods:

1. The FSA;2. The cascading event scenarios; and3. The multiple cause scenarios.

The FMECA tables are included in Appendix B of this report. These tables are organized by major project systemand the short and long term risks for that system are included in the same table.

In failure scenarios where risks were moderate to high, additional mitigating measures were recommended and therisk estimate was re-evaluated. If the risk estimate for a fault scenario was low to moderate mitigating measures mayhave been recommended but a re-evaluation of the risk rating was not completed.

3.5 Summary

The assessment of risk for the Giant Mine Remediation project was completed by utilizing a Failure ScenarioAnalysis (FSA) and a Failure Modes and Effects Criticality Analysis (FMECA) which follow the reference CanadianStandards Association Risk Analysis Requirements and Guidelines (CSA, 1991). Workshops were held to carry outthis risk assessment be identifying the major systems and components for the Giant Mine Remediation project,developing associated failure scenarios and assessing the associated risks.

The FSA method identified failure scenarios for specific initiating events and failure scenarios for specificcomponents, which effectively identifies risks in the short and long term for the Giant Mine Remediation Project. TheFSA method was used to develop failure scenarios, cascading event scenarios, and multiple cause scenarios.These scenarios were then assessed using the FMECA method. The FMECA tables are organized according to themajor project systems identified in this assessment, listed below.

Underground System Freeze System Baker Creek System Surface System Water Management System Institutional System (Management of the project) Buildings (Short Term Only)

If the FMECA tables assigned risk levels as moderate to high, additional mitigating measures were recommendedand the risk estimate was re-evaluated. As a result of applying the mitigation, the re-evaluated risk generallydecreased, either through a decrease in the likelihood of the failure or a decrease in impacts to the public,environment and/or cost.



The purpose of this assessment was to identify risks which impact the overall objective of the Giant MineRemediation Project, which include:

Manage the underground arsenic trioxide in a manner that will minimize the release of arsenic to thesurrounding environment, minimize public and worker health and safety risks during implementation, and becost effective and robust over the long term;

Remediate the surface of the site to the industrial use guidelines under the NWT Environmental ProtectionAct, recognizing that portions of the site will be suitable for other land uses with appropriate restrictions;

Minimize public and worker health and safety risks associated with buildings, mine openings, and otherphysical hazards at the site; and

Restore Baker Creek to a condition that is productive as possible, given the constraints of hydrology andclimate.



4. ReferencesSRK Consulting (SRK), 2010. Giant Mine Remediation Project Developer’s Assessment Report, EA0809-001,October 2010.

Canadian Standards Association (CSA), 1991. Risk Analysis Requirements and Guidelines. CAN/CSA-Q634-91.November 1991.

Golder Associates Ltd. (Golder), 2011. Introduction to the Systems FMECA Method for Risk Assessment.


Appendix AFailure Scenario Analysis (FSA)

Pink events are relevant in the short term

Orange events are relevant in short and long term

Blue events are relevant in the long term

InitiatingEvents

Malfunction

Failure 1 SubsequentFailure 1

Failure 2

Accident Failure 3

Accident Failure 4

ComponentFailure

Failure 1

MalfunctionInitiating Event1

Initiating Event2

AccidentInitiating Event3

Failure 2AccidentInitiating Event4

A-1

Climate Change

Loss of Capacity inReceiving

Environment

ExtremeWeather

Passive CoolingInsufficient to

Maintain Freeze

Change Treatment Criteria

High Winds

Environment(FSA-01)

Earthquake

Thin Crown PillarCollapse

Extreme Weather

Higher Probabilityof Flooding

Increase SurfaceWater Temperature in

Back Bay

Thinning of Ice at Diffuser

Melting Ice Lensesand Tailings Ponds

Change in Capacity inReceiving Water to Mix

Discharge

Damage toTailings Cover

Damage toLandfill

Progressive Deterioration of Lake Quality for Other Uses

Power Outage

Lightning Fire

Extreme Cold

Increased FuelSupply Required

Water Plant Freeze Up(either Effluent Treatment Plant

or New Mine WTP)

Precipitation

Increased Erosionof Baker Creek

Increased SiteMaintenance

Re-suspension of Contaminated Sediment

See FSA-A PillarFailure

Roaster, C-shaft& A-shaftDamage

See FSA-BBuilding Collapse

Liquefaction of Unfrozen Dust

Sill PillarCollapse

See FSA-A Bulkhead/Plug Failure

See FSA-04Flood

See FSA-02Fire

See FSA-03Power Failure

Arsenic DustRelease

BuildingCollapse

ExtremeWeather

Lack of Precipitation Drought

Cover Failure

VegetationStress

Pit Slope FailureSee FSA-CPit Slope


Pit Slope Failure(See FSA-C)

Impact toPublic Safety

Earthquake

UndergroundInstability

Minor Movement (BackfillStabilization)

DamagePassive

Freeze System

No Impact toFrozen Block

A-2

Fire(including Forest Fire)

Underground

MobileEquipment

Fire(FSA-02)

Power LineDamage

Fuel Tank Fuel Spill

Power and Air Distribution

Release of Contaminated Fire

Fighting Water

ElectricalSystem Fire

Loss of Freeze

Power Failure

Loss of BackupGenerators and

Heating Capability

Public Healthand Safety

Freeze up of Facilities

RegulatoryInvolvement Project Delay

Fuel Tank Fire

Utilidor Fire

Loss of InfrastructureCapability

Evacuation of Operating Personnel

Fire SpreadsBetweenBuildings

Evacuation of Personnel

Loss of ProjectRecords

BuildingCollapse

Fire(including Forest Fire)

Non-CompliantDischarge

Effluent TreatmentPlant

Roaster

Dust Release

PlantIn-operational

Arsene GasImpacts to

Public Health

Impacts toPublic Health

ChemicalExplosion

Forest Fire CO2 Levels Shut DownUnderground

Fire (includingForest Fire)

New MineWTP

PlantIn-operational

Rising UndergroundWater Levels

Fire SuppressionFails

ChemicalExplosion


Non-CompliantDischarge

A-3

Power to WaterTreatment Plant

Power toFreeze Plant

Loss of UndergroundVentilation

Power Loss DuringChamber Flooding

Freeze Up of Ramps

Power Failure

(FSA-03)

Failure of BackupGenerator

Backup GeneratorProvides Power

Water LevelRise in Mine

Freeze Up of WaterTreatment Plant and

Discharge Line

Effluent TreatmentPlant of Mine WTP

Rebuild

Flood Up to ArsenicTrioxide Dust

Instability of Nearby Stopes

Permanent Loss of Arsenic into Mine

Water Treatment PlantUndersized to Treat

Mine Water

Loss of Active Freezing(approximately 3 months)

Loss of Arsenic SaturatedWater Through Fractures in

Chamber

Non ComplianceDischarge Water Through

Water Treatment Plant

Limited WorkUnderground

Failure of Pumps

Pump Failure

Surface CollectionSystems Pump Back

Failure

Storage CapacityExceeded forUnderground



Fire SuppressionSystem Freezes

Building ServicesDamaged

Loss of Power to Town/Loss of Labour Force and Site Security

Loss of Power to FreezePlant

Loss of MonitoringSystem - Minor

No Impact toFrozen Block

Increase in ArsenicConcentration in Water

Effluent Treatment PlantUnable to Treat Mine

Water

Mine WaterLevel Rise

Increase in ArsenicConcentrate in Mine Water


Water

Fire SuppressionSystem Rebuild

Loss of FireSuppression

Rise inWater Level

Loss of Labour Forceand Site Security




Water

A-4

Bank OverflowLoss of Channel

Damage to NewHwy 4 Bridge

Damage to SurfaceInfrastructure

Flow into Pit

Loss of SiteAccess

Flood(FSA-04)

Damage toDams

Ditches

Local Flooding andLoss of Tailings

NoncompliantRelease of Sediment

Flooding of Underground Overloading of

Water TreatmentPlant

UndergroundInstability

Loss of WaterTreatment Supplies

for few Days

Contaminated WaterReleased to Downstream

Environment

Non ComplianceRegulatory

DamagesUndergroundInfrastructure

See FSA-AUnderground

Bank OverflowLoss of Channel Flow into Pits

Flow into andFlooding of

Underground

Loss of Pumps

Flood Up to ArsenicChambers

Non ComplianceRelease

Bulkhead FailurePre Freezing

Major ArsenicRelease

See FSA-AUnderground

Pit SlopeFailure

See FSA-C PitSlope Failure

A-5

Lack of Money

Loss of Continuityand Coordination

Inadequate Trainingand EmergencyResponse Plan

Delay Response toRemediation of Site

Loss of ProjectKnowledge

Low Reliability

Governance(FSA-05)

No Response toShort Term Events

Lack of Personnel

Poor Project Mgmt andLack of Maintenance

Inadequate Trainingand EmergencyResponse Plans

Inadequate Preparationfor Response to

Emergency Event

InadequateEquipment

Lack of GovernanceInappropriate FundingModel for Multi Year

Project

Poor ProjectDesign

Loss of Continuity

Re WorkDesign

Inability toEfficiently Respond

to RegulatoryChange

Project Delay

Non Compliance

Loss of PoliticalSupport for Project

Site BecomesUnstable

RemediationDelay

Lack of Oversight andMonitoring

Project Delayand/or Failure

Confused Roles andResponsibilities

Project Delayand/or Failure

Lack of Governance

Lack of Communication

Loss of RegulatorySupport

Regulatory NonCompliance

Loss of Credibility

CompetingInterests

CompetingMandate Interests

Limited Ability for Project Planning and

Development

All Levels of Government

Poor ProjectDecisions

Project Delayor Failure

A-6

Third Party AccessIssues

Trespass/Vandalism

ExternalThirdParty

Influences(FSA-06)

Plant Damage

Loss of Power

Fire

ChemicalSpills

Damage toCover

Damage toInfrastructure

H&S

Transportation

LegalChallenges

Project DelaysProject Design

Becomes Infeasible Project Failure

A-7

Gap Caused atCrown

ArsenicSeepage

Plug Failure

Crown PillarInstability

Short Term HighArsenic Water

Release

Mass ArsenicRelease to Mine

Water

PlannedThaw of FrozenBlock

(FSA-07)

Sill Pillar Instability

Mass ArsenicRelease to Mine

Water

IncreasedPermeability of

Rock Mass

A-8

Project Design No Longer Compliant

Design Re-Work

New Project ComponentsRequired

RegulatoryChange(FSA-08)

A-9

Off SiteAccident

TransportSystem Failure

On SiteAccident

Transportationand Storage

(FSA-09)

RoadAccident Near

Site

Fire Damage toSite Infrastructure

Site AccessInterruption

Fuel SpillAffecting Site

Loss of Supply Chain

Water Treatment Plant Runsout of Materials

WorkerAccidents

Air

Fuel andChemical

Spills

Vehicle

Work Near Storage FacilitiesLeading to Explosion

TransportSystem Failure

Loss of Supply Chain

AmmoniaSupply for

Freeze Plant

Minor Delays inFreeze

Implementation

A-10

Extreme Runoff Exceeds Capacity

Surface Failure

UndergroundFailure

Crown PillarFailure

Major FracturesBelow Alignment

Loss of Permafrost

PermafrostDegradation

Channel BankFailure

Extreme Runoff

Ice Damming andLandslide Damming

Pit SlopeFailure

ExtremeRunoff

Beaver Damming/Woody Debris

Culvert/Bridge Failure

B2 Dam Failure(Short Term)

Baker CreekLoss of

Containment(FSA-10)

A-11

Pressure ExceedsDesign During Fill

Deterioration orInadequateConstruction

InadequateDesignFlooding

Flooding

Rock Fall

Air Blast

Rock Fall

Crown Pillar

Ice Pressureand Ice DamageDuring Freezing

Improper Hydration of Concrete Due to

Abnormal Conditions

Deterioration of Concrete

ConcreteDeterioration

BulkheadFailure

(FSA-11)New Plug Failure

(Lower Drifts)

Old BulkheadFailure

A-12

Bulkhead Failure andArsenic Release to

Mine

Pillar Failure andArsenic Release to

Mine

Inaccuracy of ExistingMine Plans

UnexpectedDrilling Conditions

Mechanical SystemFailure

Failure of Freeze Pipes

Unexplained Leakfrom Chamber

Fault or Fracturesor Borehole

Release of Arsenic or

Injury

Frozen Ice CoreNot Achieved

Drilling Plan

ModelIncorrect

Failure of Wetting

Loss of Confidence(Internal/External)

Pressure to Advance with IncompleteKnowledge

H&SUnmanageable

Major Accident

Freeze Plant

Drilling

ArsenicContamination to

Worker

Lack of Water forProper Freezing of

Shell

Flooding

Time DependentDeterioration

Earthquake

InadequateDesign

Pillar Failure

Freeze PlantFailure

Failure of Freeze ProgramImplementation

(FSA-12)

A-13

Unable to Achieve Tight or Sufficient Fill

Unrecognized/UnstablePillars

Poor WorkSequencing

Unknown MineGeometry

Inadequate/Inability to

Monitor

FillCompression

Loss of Old Fill

Unknown CurrentFill Conditions

Fill Flows toLower Mine

Earthquake

Flooding

Deep MineInstability

Inaccurate/Lack/Loss of Records

InsufficientGovernance

Dust and Fill inChamber SettlesDuring Thawing

Dust and Fill inChamber SettlesDuring Wetting

Failure toImplementCrown andSill Pillar SupportSystem

(FSA-13)

A-14

Thawing

UndergroundCollapse

Loss of FillBelow Sills

Sill Pillar Failure

Long TermLoss of Power

ClimateChange

Maintenance of Passive System

Governance

Degradation Dueto Flooding

FrozenBlockFailure(FSA- 14)

A-15

Overtopping

Earthquake

QuarryOperations

UndergroundCollapse

MajorPrecipitation

Settlement

GroundVibrations

Pillar FailureNorthwestPond and

Dam 1Failure

(FSA-15)

A-16

Settlement

VegetationFailure

Deep RootedPlants

Ice Melting

Consolidation

GeotextileFailure

Fire

Drought

MechanicalErosion

BurrowingAnimals

increasedInfiltration

Boils

Frost Jacking

Deep RootedPlants

Erosion

Wind

Water

VegetationDesign

Short TermMaintenance

TailingsCover Failure

(FSA-16)

A-17

Main and BackupPower Loss

Freeze Damage

No Reagents

Power and HeatLoss

OutfallUnavailable

Frozen

Damage

PlantDamage

Fire

Fire

Flood

No Fuel

Maintenance

IncreasedInflow

Unavailability of Operators

High ArsenicLoad

High TSS

ArsenicContainment

Hi ArsenicCollection

System Failure

Flooding,Mudflow,Airblast

Pillar Failure/SlopeFailure and Creek

In-Flow

Creek Inflow

Precipitation

DesignParameter Error

Land or WaterImpact Damage

ExternalSource

InternalSource

HeatingSystem

Electrical

Transportation

Supply Chain

No Water Supply toPlant

No Access toPumps (atPresent)Underground

Failure

Impact fromExternal Source

Human Error

Vandalism

Power Failure

GroundInstability

VehicleImpact

Short Term Loss of DischargePiping from Underground to

Surface

Lack of Maintenance

Collapse of Shaft

Loss of Power

MajorComponent

Failure

Plant BeyondDesign Life

Utilidor

Regional Fire

Vehicle

WTPFailure

(FSA-17)

No Water Supply toPlant

BoreholeFailure

A-18

Bulkhead/PlugFailure

Pillar Failure

Damage toInfrastructure or

Development

Underground(FSA-A)

Leakage

StructuralFailure

Release of HighArsenic Water to

Mine Pool

Arsenic SolidsReleased to Mine

Pool Water Treatment PlantOverloaded or Overflow Mine

Pool

Non CompliantDischarge

Non CompliantDischarge

Arsenic Sill and RibPillar Failure

Arsenic CrownPillar Failure

Revised RemediationPlan Required

Pressure Shock toBulkheads

BulkheadFailure

Surface DustRelease

AirborneContaminate/Human

Exposure

UndergroundInfrastructure

Damage

Freeze SystemFailure Glycol Loss From

Freeze System

AmmoniaRelease

Hydrochloroflourocarbons(HCFC)Release from Thermosyphon

Regulatory NoncomplianceDischarge

HighwayCollapse/Fatality

Impact onHighway Users

Mine Inflow from Surface

Water

Non ArsenicCrown Pillar

Failure

Collapse of Highway

Baker CreekInflow to Mine

Flood the Surface\OverloadTreatment Plant

PowerInterruption

Power Interruption Low Voltage(approximately 30 days)

(See FSA-03)

Power Interruption High Voltage(approximately 6 months)

(See FSA-03)

Damage to Mine WaterPumping System

TemporaryLoss of Mine

Access

Water TreatmentPlant Interruption

Potential Loss of Control of HighArsenic Water

Higher ArsenicLoading TowardTreatment Plant

Arsenic Dustto Mine

VentilationSystem

Surface DustRelease

AirborneContaminate/Human

Exposure

Damage to Surface Dams

Damage to PitSlopes

Impact Baker Creek/Flood, PowerInterruption, Surface Impacts, Highway

Impact, Public Health Impacts

Arsenic Sill and RibPillar Failure

Major Loss of Arsenic Solids to

Mine Pool

Bulkhead Failure(See Bulkhead Branch Above)

Loss of Horizontaland Vertical FreezePipe Containment

Pillar Failure

Impacts toPublicSafety

Impacts to PublicHealth and Safety

Impacts toPublic Safety

Failure Scenario Analysis

A-19

walll

Text Box

Roaster

C-ShaftHeadframe

A-Shaft

Arsenic Dust andAsbestos Release

Metal andAsbestos Cladding

Release

Asbestos SidingRelease

BuildingCollapse(FSA-B)

Impacts PublicHealth and

Safety

Regulatoryand Publicity

Surface Waterand Soil

Contamination

Damage toSurroundingInfrastructure

ImpactsPublic Health

and Safety

Damage toUndergroundInfrastructure

ImpactsPublic Health

and Safety

Mill BuildingAsbestos Cladding

Release

Damage toSurroundingInfrastructure


Safety

Stack Arsenic DustRelease


Safety

Regulatoryand Publicity

Surface Waterand Soil

Contamination

A-20

Breaching of Baker Creek

HighwayDamage

Crown Pillar Failure

SeeUnderground

SeeUnderground

Pit SlopeFailure(FSA-C)

Backfill Failure inPit Bottom

DestabilizingUnderground Stopes

Failure Plane IntersectingArsenic Stopes

Damage toFreeze System

Direct Releaseof Arsenic toMine Water

Damage to FreezeSystem

Infrastructure

SeeUnderground

DirectDischarge toUnderground

Overload Water Treatment System

A1 & A2 PitIntersecting Wetland

Water in Mine

Public H&S

SeeUnderground

Mudflow andAir Blast

Impacts Water Treatment

Pit Slope Failure Cuts Off Underground Access

SeeUnderground

A-21


Appendix BFailure Mode Effects Criticality Analysis (FMECA)

Risk Matrix

B) Minor C) Moderate D) Major E) Critical

Index Event/Years

LowModerateModerately HighHighVery High

Source: INAC NCSP Project Risk Management Guidance Document

CATEGORYCONSEQUENCE SEVERITY

A) Low

I) Public Safety

Low-level short-termsubjective symptoms/ No

measurable physicaleffect/ No medical

treatment

Objective but reversibledisability/impairment

and/or medical treatmentinjuries requiringhospitalization

Moderate irreversibledisability or impairmentto one or more people

Single fatality and /orsevere irreversible

disability or impairmentto one or more people

Multiple fatalities

II) Environment No impact Minor localized or short-term impacts

Impact on valuedecosystemcomponent

Serious longtermimpairment of

ecosystem function

III) Cost $<100,000

Impact on valuedecosystem component

and medium-termimpairment of

ecosystemfunction

$100,000- 1 Million $1.0-10 Million

LIKELIHOOD

$10-50Million $ >50Million

3) Once every 30years

2)

1) More than onceevery 5 years

Once every 15years



Risk Rating

B-1

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UGS-1 Bulkheads Bulkhead and horizontalbulkhead failure duringconstruction prior tofreezing.

Accident and/or Malfunction:Accelerated deterioration ordamage to bulkheads.

Damage or deterioration ofbulkheads may allow arsenic to bereleased to main mine area.Potential exists for arsenic dust tobe released into the mine pool withan increase in the amount of arsenicladen water that will requiretreatment.

4 A A C The care and maintenance of the bulkheadsand underground water managementoccurring prior to the start of the project willcontinue until all identified bulkheads arestabilised through priority sequencing.Bulkhead surveillance program will continuein the short term and emergency action willbe taken where necessary to stabilisebulkheads. Construction activities will becoordinated to minimize risk to arseniccontainment. Pressure relief will be installedas necessary during the construction phase.Should bulkhead failure or plug leakage occurthe Water Treatment Plant is sized andoperated to accommodate the additionalarsenic concentration to prevent release ofarsenic to the environment.

This risk is present with the current dryconditions of the arsenic dust containedbehind bulkheads. Pressure relief isanticipated to be effective duringconstruction phase. Measures will reducerisk, but likelihood is not materiallychanged before frozen conditions in thestopes/chambers are established. Plugsserve to reduce the risk of a failurescenario with water inflow from BakerCreek. (See Baker Creek System andWater Management System). It isanticipated that a new plug failure will onlybe a partial failure. Where exterior plugsare installed to contain arsenic dust, thesewill be designed to withstand not only dryconditions but for the fully saturated headof wetted, but not yet frozen dust.

High

UGS-2 Plugs New plug failure duringconstruction.

Malfunction: Improper hydration ofconcrete due to abnormalconditions, deterioration ofconcrete, rock fall, pressureexceeds design duringstope/chamber wetting, icepressure and ice damage duringfreezing resulting in partial plugfailure.

Partial failure may allow arsenic tobe released to unfrozen mine areas.Potential exists for thousands oftonnes of arsenic dust released intothe mine pool with a substantialincrease in the amount of arsenicladen water that will requiretreatment.

5 A A C The care and maintenance of the bulkheadsand underground water managementoccurring prior to the start of the project willcontinue until all identified bulkheads arestabilised through priority sequencing.Bulkhead surveillance program will continueand emergency action will be taken wherenecessary to stabilise bulkheads.Construction activities will be coordinated tominimize risk to arsenic containment.Pressure relief will be installed as necessaryduring the construction phase. Shouldbulkhead failure or plug leakage occur theWater Treatment Plant is sized and operatedto accommodate the additional arsenicconcentration to prevent release of arsenic tothe environment.

This risk is present with the current dryconditions of the arsenic dust containedbehind bulkheads. Pressure relief isanticipated to be effective duringconstruction phase. Measures will reducerisk, but likelihood is not materiallychanged before frozen conditions instopes/chambers are established. Plugsserve to reduce the risk of a failurescenario with water inflow from BakerCreek. (See Baker Creek System andWater Management System). It isanticipated that a new plug failure will onlybe a partial failure. Where exterior plugsare installed to contain arsenic dust thesewill be designed to withstand not only dryconditions but for the fully saturated headof wetted, but not yet frozen dust.

High

UGS-3 Crown pillar failure atarsenic chambers duringconstruction.

Accident: Collapse through toground surface.

Release of arsenic dust toatmosphere.

3 B C C Backfilling the void under the crown pillar.Maintenance of site accident controls. In theevent of a substantial dust release, acommunity notification protocol will befollowed.

Tight backfilling of voids is planned. 5 B C C High

UGS-4 Non-arsenic crown pillarfailure during construction


Potential for impact to highway,public areas and parking lot overunsupported voids, as well asdamage to pit slopes and BakerCreek.

4 D A C Void under crown pillars will be filled. Furthersite characterization will continue to identifyall voids requiring backfilling. Wheresubsidence may occur, backfilling will becompleted.

Backfilled voids will not present a risk ofserious collapse.

5 B A C Moderate

Short Term

Crown Pillar

ConfidenceEstimate

FMECA - Giant Mine Remediation Program

Risk Scenario Event Sequences Chart: Underground System

PLANNED MITIGATION/CONTROLS/MANAGEMENT MEASURES EVALUATION

LIK

ELIH

OO

D

CONSEQUENCESEVERITY

EVENT/CAUSES POTENTIAL CONSEQUENCES

LIK

ELIH

OO

D

CONSEQUENCESEVERITY

ID COMPONENT SUBCOMPONENT RISK ISSUE /FAILURE

B-2

UGS-5 Sill Pillar Sill pillar failure at arsenicchambers duringconstruction

Accident: Collapse due to rock orground support degradation

Loss of arsenic dust to mine pooland to the ventilation system.Potential exists for thousands oftonnes of arsenic dust released intothe mine pool with a substantialincrease in the amount of arsenicladen water that will requiretreatment.

3 B B D Voids under sill pillars will be backfilled. Thiswill include cementatious backfill in criticalareas, and additional support for sill pillarswhere required. In the event of a sill pillarcollapse that results in an increase in arsenicconcentration in the mine water pool theWater Treatment Plant is sized and operatedto accommodate the additional arsenicconcentration to prevent release of arsenic tothe environment. To minimize the release ofarsenic dust to the atmosphere the mineventilation system will be shut down followinga sill pillar collapse. In the event of asubstantial dust release a communitynotification protocol will be followed.

All sill pillars are currently subject to long-term monitoring. This will continue duringthe remediation phase. Despite the loss ofa sill pillar an attempt will be made tofreeze the affected chamber. Stressincrease to the sill pillars from wettingwould not occur until after backfilling andfrozen shell thus minimising the risk of afailure event.

5 A A C Moderate

UGS-6 Sill pillar failure at arsenicchambers

Accident / Malfunction: Collapsedue to rock or ground supportdegradation and water movementcausing instability.

Loss of immediate support to backfillunder arsenic chambers.

4 A A C More backfill will be added. Long-term monitoring will continue. Allchambers will be frozen and voidsbackfilled minimizing the risk ofoccurrence and consequences.

5 A A C Moderate

UGS-7 Movement of non-arsenicrelated backfill due to largefluctuations in minewaterlevel.

Accident: Upset conditionassociated with Baker Creek (SeeBaker Creek System for Scenarios)

Such an event has the potential toaffect both water storage andtreatment. A flood event willincrease the amount of water storedunderground and subsequentlytreated.

5 A A C The volume of water treated through theWater Treatment Plant may temporarilyincrease to draw down the mine pool water tothe target level. Discharged water will remaincompliant.

The length of time to reach mine storagecapacity is uncertain.

Low

UGS-8 Crown Pillar Non-arsenic Crown PillarFailure.


Potential for impact to highway,public areas and parking lot throughloss of immedate support to backfillunder stopes.

5 C A C More backfill will be added. Wheresubsidence may occur post-backfilling will becompleted.

Backfilled voids will not present a risk ofserious collapse.

Moderate

Sill PillarLong Term

B-3

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FS-1 Drilling Failure (Single DrillHole)

Malfunction: Inaccuracy of existing mineplans may mean that some holes areinitially drilled too close or too far fromchambers. Unexpected drillingconditions such as discontinuities in therock or intersecting an existing drill holeor shear zone may be encountered.

Drilling circulation may be lost. Arsenic dustmay be released to surface, if there isdrilling into a chamber or stope.

1 A A B Where a drill hole intersects the freezehole, layout will be refined and the holeredrilled. Where a drill hole enters achamber, shut-down and controlprocedures will be followed to minimise therelease of dust. In the event of a dustrelease, a community notification protocolwill be followed.

Failures will be single events and will notsubstantially affect the timing or ability toestablish a frozen block.

4 A A B Moderate

FS-2 Drilling Failure (Entire FreezeProgram)

Malfunction: Inaccuracy of existing mineplans, unexpected drilling conditions,find existing drill hole or shear zone.

Failure of a substantial number of drill holeshas the potential to delay the establishmentof the frozen blocks. Multiple failurespresent the same risks as single holefailures.

1 A A C The drilling results would be used to refinefreeze hole layout. Holes would beredrilled and the project scheduleamended accordingly. Where a drill holeenters a chamber, shut-down and controlprocedures will be followed to minimise therelease of dust. In the event of a dustrelease, a community notification protocolwill be followed.

Failures will be single events. Whiletiming will be affected, drill failures will notimpact the ability to establish frozen block.Up to 5% of holes are anticipated to beredrilled to account for unexpectedconditions.

3 A A C Moderate

FS-3 Active Freeze System Extended time to establish afrozen shell

Malfunction and/or Accident: Vibrationfrom quarrying operation or earthquakeleading to damage of the active freezesystem.

Delay in establishing frozen block andincrease in cost.

5 A A C Time to freeze the shell will be recalculatedand the project schedule amendedaccordingly. Grouting of rock fractures willbe completed.

While timing will be affected, only thelength of time and potentially an increasein the energy required to freeze the shellwill be required. No resultingconsequences.

High

FS-4 Frozen Shell Extended time to establish afrozen shell

Accident: Water in the rock higher thanpredicted.

The latent heat and flow of this watercauses an extension in the freeze time.

4 A A B Time to freeze the shell will be recalculatedand the project schedule amendedaccordingly. Grouting of high groundwaterflow will be completed.

While timing will be affected, only thelength of time and potentially an increasein the energy required to freeze the shellwill be required. No resultingconsequences.

Moderate

FS-5 Planned Thaw Causes Failure(Engineered)

Natural thaw, the application of heat byreversing the cooling system or otherunknown method.

Degraded rock quality, crown pillar and sillpillar failure fractured during freezing causesincreased permeability of rock massincreasing groundwater capture, allowinghigh concentration arsenic contaminatedwater to reach mine pool. Additional waterfrom thawing puts stress on plugs.

5 A A C Water Treatment Plant is sized andoperated to accommodate the additionalarsenic concentration to prevent release ofarsenic to the environment. Untiladditional plant components areconstructed that can process contaminatedwater to achieve compliant dischargewater will be stored underground.

As this would be a planned, engineeredevent, it is anticipated that the risks ofsuch an undertaking would undergo aseparate full review and assessment. Athaw would be very slow, taking decades.

High

FS-6 Unplanned Thaw CausesFailure

Accident: Climate Warming Degraded rock quality, crown pillar and sillpillar failure fractured during freezing causesincreased permeability of rock massincreasing groundwater capture, allowinghigh concentration arsenic contaminatedwater to reach mine pool.

5 A A C The current freeze system is designed toexceed the prediction for climate change.In the event that local climate warming farexceeds modeled predictions the passivefreeze system would be expanded with theoption of supplementing the passivecooling with active cooling.

Ground and air temperature and minewater monitoring would detect early signsof change to the frozen block, beforeactual melting would start to occur.Remedial action could be taken for one orall of the blocks before any thaw. A thawwould be very slow, taking decades.

High


Malfunction: Failure of freeze system Degraded rock quality, crown pillar and sillpillar failure fractured during freezing causesincreased permeability of rock massincreasing groundwater capture, allowinghigh concentration arsenic contaminatedwater to reach mine pool.

5 A A C The freeze system will be repaired orupgraded as necessary and re-established. The Water Treatment Plant issized and operated to accommodate theadditional arsenic concentration to preventrelease of arsenic to the environment.

Ground and air temperature and minewater monitoring would detect early signsof change to the frozen block, beforeactual melting would start to occur.Remedial action could be taken for one orall of the blocks before any thaw. A thawwould be very slow, taking decades.

High


Malfunction: Long-term loss of powerand passive cooling ineffective

Degraded rock quality, crown pillar and sillpillar failure, fracturing due to freezing,increased permeability of rock mass,increased arsenic load to water, increase ingroundwater capture, release of arseniccontaminated water to mine pool.

5 A A D The freeze system will be repaired orupgraded as necessary to maintaineffective cooling and re-established. TheWater Treatment Plant is sized andoperated to accommodate the additionalarsenic concentration to prevent release ofarsenic to the environment.

Ground and air temperature and minewater monitoring would detect early signsof change to the frozen block, beforeactual melting would start to occur.Remedial action could be taken for one orall of the blocks before any melting wouldstart to occur. A thaw would be veryslow, taking decades and would notimpact restoration of power or the frozenblock.

High

FS-9 Wildfire damages the passivecooling system

Accident: Wildfire Repairs to the cooling and monitoringsystems are required.

5 A A C Vegetation will be controlled around thepassive cooling piping.

Repairs would easily be made before anyfrozen block thaw. Thaw would be veryslow, taking decades. No resultingconsequences.

High

FS-10 Warming from climate changeexceeds cooling capacity ofexisting passive coolinginfrastructure

Accident: Global warming vastly greaterthan maximum predictions. Reducedefficiency of passive freezing system.

Upgrade to current freeze infrastructure. 5 A A D The freeze infrastructure will upgraded asnecessary to maintain effective cooling andre-established.

Ground and air temperature and minewater monitoring would detect early signsof change to the frozen block, beforeactual melting would start to occur.Remedial action could be taken for one orall of the blocks before any melting.Thaw would be very slow, taking decadesand would not impact restoration of thefrozen block.

High

FMECA - Giant Mine Remediation Program

Risk Scenario Event Sequences Chart: Freeze System

SUBCOMPONENT EVENT/CAUSES POTENTIAL CONSEQUENCES Confidence EstimateEVALUATION

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Frozen Block

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BCS-1 Baker Creek overflows duringconstruction.

Accident: Channel partially orcompletely blocked with ice, rockand / or beaver dams.

Water would overflow into pits, spill into theunderground and flood the undergroundworkings. Mine water arsenic concentrationwould potentially reach levels 100 timescurrent values. Erosion off tailings in BakerPond impacts water quality in the creek.

4 A D C Ice build-up in the channel will continue tobe monitored and cleared as possible.Damage to dykes will be repaired.Supplies of emergency response materialswill continue to be maintained on-site, suchas aquadams, liners, and equipment. SeeWater Management System table formeasures related to mine inundation.

Channel wall failure occurs duringfreshet; Impractical to mediate duringflow; Pumping system isoverwhelmed; Current channelcapacity is a 1:200 year event withno ice dam or other blockage.Adding 1m of fill over 100m length atC1, capacity moves close to 1:500year storm. Good information base.

5 A D C High

BCS-2 Bank damage during construction Accident and/or Malfunction:Machine damage or othermechanism resulting in sedimentbeing released into environment.

Impact to fish or fish habitat. 1 A C B Construction will be scheduled to occuroutside of restricted periods. Erosioncontrol measures will be in place for allworks in and around the creek.Construction monitoring will addressdeficiencies. An emergency response planwill be in place.

It is typically difficult to prevent allsediment release during proposedlocal re-alignment. All constructionimpacts around Baker Creek areanticipated to be short-term.

3 A B B High

BCS-3 Ground vibration from quarryingoperation or earthquake leading tothe collapse of a crown pillarcompromising pit wall stabilityleading to a compromise of pillarsunder creek which results in the lossof containment of Baker Creekwhich now flows into theunderground mine duringconstruction.

Malfunction and/or Accident:Vibration from quarrying operationor earthquake.

Water would overflow into pits, spill into theunderground and flood undergroundworkings. Mine water arsenic concentrationwould potentially reach levels 100 timescurrent values.

5 A D C Should mine inundation occur the newWater Treatment Plant will be sized andoperated to accommodate the additionalarsenic concentration to prevent thecontinued long-term release of arsenic tothe environment. Emergency pumpingcapacity would be sourced and installed.

There is a short period of exposureto this risk: 2 years for theconstruction for Baker Creek local re-alignment. Risk rating does notchange with mitigation as they areresponses not preventions.

High

BCS-4 Baker Creek loses channelcontainment during Freshetresulting in large inflows to the mineunderground workings.

Accident: Loss of ground support atC1 Pit and A2 Pit Raise

Water would spill into the underground andflood underground workings. Mine waterarsenic concentration would potentiallyreach levels 100 times current values andflood to surface in open pits with potentialrelease to the environment. Loss of currentmine dewatering system. Initiation of backfillinstability.

3 B D E Conduct additional investigations to confirmstability assessments (previous andcurrent) and implement monitoringprogram. Consider alternative creekalignment options to those in remedial planthat minimizes risk, balances restorationand fisheries objectives with site andproject cost restraints. Emergencyupstream flow diversion to prevent fromcontinuous inflow.

Based on delayed care andmaintenance cost and increasedwater treatment cost. Potentialsignificant underground instabilityissues that require mitigation. Likelysuspended sediment discharge intowatercourse with emergency streamdiversion. This assumes thatunderground backfilling has nottaken place yet at A2 Pit Raise.

3 B C D Low

BCS-5 Seepage from Baker Creek floodsStope C212 and/or Chamber 14during construction.

Accident: A new seepage pathwaydevelops, through a mechanismsuch as an existing drill hole orsubsidence near pit crest that isconnected to the underground.

Bulkhead failure (plug construction inprogress) with arsenic dust lost into lowerportion of mine. Water from Baker Creekflows into the mine resulting in majoraddition of water to the mine. Arsenicconcentration could potentially be 1000times higher than current levels. However,water is contained within the mine and doesnot overflow to the environment. Chambercannot be frozen as planned. Major costconsequence as chamber cannot be frozenand therefore there is a significant increasein water treatment costs. Water storedunderground until water treatment capacityis increased, consequently there is norelease to the environment.

4 A A D Ongoing seepage monitoring at bulkheads.Where monitoring results indicate pressurebuild up, relief valves could be installed.Plugs will be installed in C212, B208 andChamber 14 with pressure release valves.

This scenario results in less waterentering the mine due to the limitedflow from seepage vs. a freshetflooding event. There is a shortperiod of exposure to this risk: 2years for construction of plugs inC212, B208 and Chamber 14 drifts.No malfunction scenario anticipatedas the result of Baker Creek local re-alignment.

5 A A D High

BCS-6 Bank Overflow Accident: Stable channel overflowsduring large flow greater than thedesign flows.

No inflow to the mine up to nominal 1:500year flood event. Accumulation of additionalwater in mine pool. No release to theenvironment.

4 A A B Long-term maintenance of Baker Creek tomaintain flood design capacity. Surplusvolume above the 1:500 flood can bestored in the mine and can be treated in thewater treatment system. No impact tofrozen stopes/chambers.

High

FMECA - Giant Mine - Risk Assessment of Remediation Program

Risk Scenario Event Sequences Chart: Baker Creek System

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BCS-7 Bank Overflow Accident: Glaciation of channelthrough mine site area.

Overflow into mine at various points.Accumulation of additional water iscontained in mine pool. No release to theenvironment.

3 A A B Long-term maintenance of Baker Creek tomaintain channel integrity during wintermonths. Tailings covered in Baker Pond.

Likelihood reflects observation ofrecent events.

High

BCS-8 Ground Collapse Breaks Through toSurface Under Baker Creek

Accident: Earthquake. No mechanism leading to collapse asbackfilling of critical mine openingscompleted.

5 A A A All critical mine openings are backfilled and/ or stabilized; Backfill designed againstliquifaction; Consider alternative creekalignment options to those in remedial planthat minimizes risk, balances restorationand fisheries objectives with site andproject cost restraints; Long-termmaintenance as necessary.

All critical mine openings areidentified through historical searchand review of current data and/orinvestigation.

High

BCS-9 Channel Deterioration Accident: Permafrost thawing anderosion.

Sediment release, loss of rip-rap, channelconfiguration (loss of flood plain and risk ofoverflow into mine).

4 A A B Long-term maintenance of Baker Creek tomaintain channel integrity.

Ground ice to be addressed duringconstruction if encountered.

High

BCS-10 Baker Creek loses channelcontainment during Freshetresulting in large inflows to the mineunderground workings.

Accident: Loss of ground support atC1 Pit and B2 Pit

Water would spill into the underground andflood underground workings. Loss of minedewatering system. Water floods frozenstopes, chambers and workings and tosurface via pits. Non-compliant dischargefrom Water Treatment Plant and potentialrelease to the environment via pits.

3 B C C Consider alternative creek alignmentoptions to those in remedial plan thatminimizes risk, balances restoration andfisheries objectives with site and projectcost restraints.

5 B C C Moderate

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SS-1 Accident / Malfunction: Release ofponded water by overtopping.

Major precipitation. Release of untreated water fromtailings ponds. Short term watertreatment failure and reduced capacityto store water underground.

5 A C C Ponds maintained with a 1 meterfree board that allows for major stormevents.

The 1 meter freeboard allows forsubstantial storage for a majorrainfall event. In the event of thefreeboard being exceeded, waterwill be discharged into theunderground. Implications tounderground water storage andwater treatment addressed on theWater Management System sheet.No resulting consequences.

High

SS-2 Accident / Malfunction: Groundvibrations.

Earthquake or quarrying operations. Accelerated settlement and potentialovertopping.

5 A C C Monitored blasts at quarry as part ofquarry operations.

The dams are stable structures. Inthe event of overtopping, water willbe discharged into theunderground. Implications tounderground water storage andwater treatment addressed on theWater Management System sheet.No resulting consequences.

High

SS-3 Dam 21B and Dam 1 Accident: Flooding Major storm causing flood. Damage to Dam 21B and Dam 1, localflooding and minor loss of tailingsdownstream and into surroundingenvironment.

5 A C C Ponds maintained with 1 meter freeboard that allows for major stormevents. In the event of seriousdamage, water retained by Dam 1would be discharged to underground.

Unlikely event for rainfall notexceeding the 24-hour, 100 yearstorm event. No resultingconsequences.

High


3 A C B Ditches will be upgraded to finaldesign standard including rip-rapcover treatment on erodible finematerial.

Erosion and sediment controlduring construction will reduce therisk of sediment releases.

4 A C B High

SS-5 Accident: Consolidation / Settlement Permafrost melting, consolidation, orgeotextile failure.

Potential for localized disruption ofsurface water drainage, minor exposedtailings, localized increased infiltration.

3 A A C Monitoring during construction andreconstruction as necessary.Construction sequencing.

No off-site sediment or tailingstransport. No resultingconsequences.

4 A A C High

SS-6 Accident: Development of Boils Frost jacking. Potential for localized failure and minortailings exposure.

2 A A C Monitoring during construction andreconstruction as necessary.Construction sequencing.


4 A A C High

SS-7 Accident: Erosion Extreme rainfall on recentlycompleted cover or on cover duringconstruction.

Potential for erosion creating run-offchannels, sediment release and tailingsexposure.

2 A A B Monitoring during construction andreconstruction as necessary.Construction sequencing.

Impacts will be limited by theselection of tailings cover materialand revegetation plan.

High

SS-8 Dams Dam 1, Dam 21 and 22Failure

No Long Term Ponds so riskeliminated. Ponds are covered.

Risk eliminated No resulting consequences. High


4 A C B Long term configuration constructed.Long term erosion maintenance asnecessary.

Final erosion protection measureswill reduce the risk of sedimentreleases. No resultingconsequences.

High

SS-10 Public Safety Public Access Accident: Injury or fatality Unauthorized public access to sitehazards such as open pits.

Injury or fatality. 5 D B B Site security and additional physicalmeasures such as fencing, cappingand berms will be maintained aroundhazards such as steep slopes andopen pits.

Measures will limit the risk of anincident.

5 B A A Moderate

SS-11 Accident: Consolidation / Settlement Permafrost melting, consolidation,geotextile failure

Surface water drainage, exposedtailings, localized increased infiltration.

4 A A C Long term maintenance asnecessary.


High

SS-12 Accident: Development of Boils Frost jacking, deep rooted plants Localized failure and minor tailingsexposure.

4 A A C Long term maintenance asnecessary.

No off-site sediment or tailingstransport.

High

SS-13 Accident: Erosion Water and wind Erosion of run-off channels andsediment release.

4 A A B Long term maintenance asnecessary.

Impacts will be limited by tailingscover material and revegetationplan.

High

SS-14 Accident and/or Malfunction: Limitedvegetation success

No maintenance / poor vegetationdesign (local plants and vegetation),drought, mechanical erosion, fire,burrowing animals.

Erosion creating run-off channels,sediment release and tailingsexposure.

3 A A B Long term maintenance asnecessary.

No resulting consequences. High

RISK ISSUE /FAILURE

Tailings Covers(including spillway)

Tailings Covers

EVENT/CAUSES

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Long Term

FMECA - Giant Mine - Risk Assessment of Remediation ProgramRisk Scenario Event Sequences Chart: Surface System

Dam 1, Dam 21 and 22Dams


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FMECA - Giant Mine - Risk Assessment of Remediation ProgramRisk Scenario Event Sequences Chart: Surface System


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SS-15 Malfunction: Incompatible land-use Change in land-use damages cover. Exposure of tailings. 3 A A B Restrict land use to compatible uses.Where an incompatible use isproposed undertake necessary sitemeasures to protect the tailingscover.

Preventing the development ofincompatible land uses dependson continued governance of thesite. No resulting consequences.

High

SS-16 Accident and/or Malfunction: Coverpenetration

Deep-rooted invasive species. Increased water infiltration and metaluptake in plants.

4 A A B Removal of deep rooted plants asnecessary.

Monitoring and maintenance isanticipated to minimise invasivedeep rooted plants in damagingtailings covers. No resultingconsequences.

High

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WMS-1 Accident: Existing plant is substantiallydestroyed by fire, either by forest fire or othercauses.

No water treatment in the year of the fire;Contaminated water remains in theunderground water pool.

4 A A C The construction of the planned news water treatmentplant would be accelerated. Temporary watertreatment system established as required.Contaminated water would remain in the mine pooluntil a new plant is constructed.

A short-term replacement plant will likely beunnecessary given that water can be storedunderground for this time period.

5 A A C High

WMS-2 Malfunction: Mechanical failure 3 A A B Ongoing maintenance of the existing plant willcontinue until the new plant is operational.

Past maintenance has been effective in maintainingplant operations.

High

WMS-3 Malfunction: Plant deterioration 3 A A B Mechanical systems will be repaired or replaced asnecessary to maintain treatment functions.

This is consistent with current practice and willcontinue.

High

WMS-4 Accident: Freeze up 3 A A B In the event of loss of heating at the plant, systemswould be drained to prevent damage. In the event ofa freeze event damaging plant components thesewould be rebuilt to restore plant function.Contaminated water would remain in the mine pooluntil the plant is operational.

Specific procedures will be developed as part of theWater Treatment Plant operating system, includingemergency response and recovery actions.

High

WMS-5 Malfunction: Current re-agent supplierunable to meet demand.

3 A A B Reagents would be sourced from several suppliers.Reagents inventory held onsite. Contaminated waterwould remain in the mine pool until the plant is againoperational.

More than one supplier of the reagent is available.Cost to change is unknown, but is conservativelyestimated.

High

WMS-6 Existing Plant Power Supply Loss of power supply to the plant Accident and/or Malfunction: Loss of thepower line to the plant causing a disruption inthe power supply to the plant for one month.

No water treatment for one monthrequiring storage of untreated waterunderground in the mine.

3 A A B Contaminated water would remain in the mine pooluntil power is restored.

A short-term replacement plant will likely beunnecessary given that water can be storedunderground for this time period.

High

WMS-7 Settling/ Polishing Polishing Pond Suspended solids are noteffectively removed in the settlingand polishing ponds

Malfunction: Upset in settling system Discharge to the environment would notbe possible. Possible to re-suspendsediment in Spring.

3 A A B Monitoring of suspended solids will be maintained toensure flocculent levels are adequate. Equipment willbe maintained to limit risk of an upset. If TSS inexceedance of discharge standards are encounteredthe water in the ponds will be recirculated fortreatment before discharge.

Regular monitoring is a built-in mitigation to limit thelikelihood of discharging poor quality water.

High

WMS-8 Bulkhead Failure and/or leakingfrom plug failure duringconstruction prior to freezing.

Accident and/or Malfunction: Accelerateddeterioration or damage to bulkheads orpartial plug failure.

4 A A C The care and maintenance of the bulkheads andunderground water management occurring prior to thestart of the project will continue until all identifiedbulkheads are stabilized or plugs constructed throughpriority sequencing. Bulkhead surveillance programwill remain ongoing and emergency action will betaken where necessary to stabilize bulkheads.Construction activities will coordinated to minimize riskto arsenic containment. Pressure relief will be installedas necessary during the construction phase. Shouldbulkhead failure or plug leakage occur the WaterTreatment Plant will be sized and operated toaccommodate the additional arsenic concentration toprevent release of arsenic to the environment.

This risk is present with the current dry conditions ofthe arsenic dust contained behind bulkheads. Whereexterior plugs are installed to contain arsenic dustthese will be designed to withstand not only dryconditions but for the fully saturated head of wetted,but not yet frozen dust. In the short-term risk isreduced but likelihood is not materially changedbecause frozen conditions have not beenestablished. Scenarios involving mechanisms ofwater inflow are covered in the Baker Creek System.

High

WMS-9 New Plug Failure DuringConstruction

Malfunction: Improper hydration of concretedue to abnormal conditions, deterioration ofconcrete, rock fall, pressure exceeds designduring fill, ice pressure and ice damageduring freezing resulting in partial plugfailure.

5 A A C Plug design will take into account hydration factors,ice pressure impact and deterioration factors. Designof plugs will be such that they will not be able tocompletely fail. Should plug leakage occur the WaterTreatment Plant will be sized and operated toaccommodate the additional arsenic concentration toprevent release of arsenic to the environment.

Where exterior plugs are installed to contain arsenicdust these will be designed to withstand not only dryconditions but for the fully saturated head of wetted,but not yet frozen dust.

High

WMS-10 Sill Pillar Failure at ArsenicChambers/Stopes DuringConstruction

Accident: Collapse due to rock or groundsupport degradation.

Loss of arsenic dust to mine pool and tothe ventilation system. Potential exists forthousands of tonnes of arsenic dustreleased into the mine pool with asubstantial increase in the amount ofarsenic laden water that will requiredtreatment through the Water TreatmentPlant.

3 B B D Voids under sill pillars will be backfilled. This willinclude cementatious backfill in critical areas, andadditional support for sill pillars where required. In theevent of a sill pillar collapse that results in an increasein arsenic concentration in the mine water pool theWater Treatment Plant will be sized and operated toaccommodate the additional arsenic concentration toprevent release of arsenic to the environment. Tominimize the release of arsenic dust to theatmosphere the mine ventilation system will be shutdown following a sill pillar collapse. In the event of asubstantial dust release, a community notificationprotocol will be followed.

All sill pillars are currently subject to long-termmonitoring. This will continue during the remediationphase. Despite the loss of a sill pillar an attempt willbe made to freeze the affected chamber. Stressincrease to the sill pillars from wetting would notoccur until after backfilling and frozen shell havebeen completed, thus minimizing the risk of a failureevent. A visible dust release may result in aperception that impacts are higher than actual.

5 A A C Moderate

Short Term


Risk Scenario Event Sequences Chart: Water Management System

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Partial failure may allow arsenic to bereleased to main mine area. Potentialexists for thousands of tonnes of arsenicdust released into the mine pool with asubstantial increase in the amount ofarsenic laden water that will requiredtreatment through the Water TreatmentPlant.

Undergroundstorage

Concentration of arsenic inmine water pool.

ConfidenceEstimate

Inability to treat water

COMPONENT

Treatment Capacity

No water treatment for two months.

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WMS-11 Significant increase in mine waterarsenic concentration from thefailure of an arsenicchamber/stope.

Accident: Seepage from Baker Creek floodsC212 and/or B208 and/or Chamber 14during construction

Hydrostatic pressure in a flooded chambercauses a bulkhead failure before or duringplug construction resulting in the loss ofarsenic dust as a slurry into the lowerportion of mine. Arsenic concentrations inthe mine water pool have the potential toreach 1000 times higher than currentconcentration. Chamber cannot be frozen.Major cost consequence as chambercannot be frozen and therefore there is asignificant increase in water treatmentcosts. Water stored underground untilwater treatment capacity is increased,consequently there is no release to theenvironment.

4 A A D Water Treatment Plant is sized and operated toaccommodate the additional arsenic concentration toprevent release of arsenic to the environment. Until aplant is constructed that can process contaminatedwater to achieve compliant discharge, water will bestored underground.

Accelerated construction of a new plant will take sixmonths. Water can be stored underground for thistime period.

5 A A D High

WMS-12 Vibration from quarrying operationor earthquake.

Malfunction and/or Accident: Collapse of acrown pillar compromising pit wall stability orpit slope stability leading to a compromise ofpillars under creek which results in the lossof containment of Baker Creek which nowflows into the underground mine duringconstruction.

Potential release to the environment.Mine water arsenic concentrationpotentially reaching levels 100 timescurrent values.

5 A D C Should mine flooding occur the new Water TreatmentPlant will be sized and operated to accommodate theadditional arsenic concentration to prevent the releaseof arsenic to the environment. Emergency pumpingcapacity would be sourced and installed while newpermanent pumping capacity is built.

There is a short period of exposure to this hazard asthe re-alignment of Baker Creek is anticipated to becomplete within two years of the start of the project.

High

WMS-13 Pumps Overflow of pump back at 22B Accident: Local power failure, site powerfailure

Overflow into environment affectingTrapper Lake.

5 A B A Local diesel backup generators will be used. Seep will dry up in the long-term after tailings arecovered.

Moderate

WMS-14 Inability to produce complianteffluent water and maintain waterlevel in the mine

Malfunction: Plant under designed for thetreatment volumes and arsenicconcentrations.

Underground storage in the mine will beused up over time as the plant will nothave the capacity to process all of thecontaminated water for release ascompliant effluent.

4 A A C Robustness will be built into the system, limitations willbe relevant around capacity. The plant will bedesigned for flow and concentration at the beginningof the remediation phase, when inflow is the highest.If the plant is found to be undersized additionaltreatment capability will be added to the plant. Theplant will be modified as necessary during the periodicrecapitalization of the facility (every 25 years).

With the creation of the frozen block flows will befurther reduced. Additional studies are planned toimprove on current mine storage calculations.

Low

WMS-15 Accident: Forest fire 5 A A B Fuel management will occur around the plant andpower line to minimize the change of impact from aforest fire.

Fuel management and a fire suppression plan willmaintain the risk as low over the very long term.

High

WMS-16 Malfunction: Maintenance failure 5 A A B A maintenance management program and arecapitalization plan will be established for the plant.Mechanical systems will be repaired or replaced asnecessary to maintain treatment functions.

Recapitalization is expected to occur every 25 years. High

WMS-17 Malfunction: No generator fuel 5 A A B Back-up generation capacity will be standard for allkey components of the project.

In the event of a prolonged power outage water willremain underground. With the creation of the frozenblock contact water will be eliminated.

Moderate

WMS-18 Malfunction: Lack of grid power 5 A A B Back-up generation capacity will be standard for allkey components of the project.

In the event of a prolonged power outage water willremain underground. With the creation of the frozenblock contact water will be eliminated.

Moderate

WMS-19 Malfunction: Failure of mechanical systems 4 A A C A maintenance management program and arecapitalization plan will be established for the plant.Mechanical systems will be repaired or replaced asnecessary to maintain treatment functions.


WMS-20 Malfunction: Plant freeze up 4 A A C In the event of loss of heating to the plant, systemswould be drained to prevent damage. In the event ofa freeze event damaging plant components thesewould be rebuilt to restore plant function.Contaminated water would remain in the mine pooluntil the plant is again operational.

The operating plan for the plant will include anemergency and recovery component to limit thedown time of the plant in the event of an accident. Inthe event of a prolonged plant outage water willremain underground. With the creation of the frozenblock contact water will be eliminated.

High

WMS-21 Malfunction: Reagent supplier unable tomeet demand

4 A A C Reagents would be sourced from a new supplier.Contaminated water would remain in the mine pooluntil the plant is again operational.

More than one supplier of the reagent is available.Cost to change is unknown, but is conservativelyestimated

High

WMS-22 Malfunction: Lack of maintenance. 4 A A C A maintenance management program and arecapitalization plan will be established for the plant.Mechanical systems will be repaired or replaced asnecessary to maintain treatment functions.


WMS-23 Movement of non-arsenic relatedbackfill due to large fluctuations inminewater level

Accident: Upset condition associated withflooding from Baker Creek.

Such an event has the potential to affectboth water storage and treatment. A floodevent will increase the amount of waterstored underground.

5 A A C The volume of water treated through the watertreatment plan may temporarily increase to draw downthe mine pool water to the target level. Dischargedwater will remain compliant. Surface subsidencewhere it presents a hazard will be filled.

With the creation of the frozen block, contact waterwill be eliminated.

High

Long TermNew WTP

Major Water Treatment Outage

No water treatment for 3 months.Main and Backup Power Loss

Undergroundstorage


Power Supply

UndergroundStorage


No water treatment for 3 months

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COMPONENT

WMS-24 Frozen Block Thawing -- climatechange

Accident: Degraded rock quality, crown pillarand sill pillar failure fractured during freezingcauses increased permeability of rock massincreasing ground water capture, allowinghigh concentration arsenic contaminatedwater to reach mine pool. Additional waterfrom thawing puts stress on plugs.

Release of arsenic contaminated water tomine pool and ultimately to WaterTreatment Plant.

5 A A C Expansion of freeze system to overcome the warming.This work would be completed well in advance ofchambers thawing out.

Natural thawing would affect all chambers. Freezesystem is designed for consequences of climatechange. Passive cooling does not rely on long termpower for continued function.

High

WMS-25 Frozen Block Thawing --Malfunction: Failure of freezesystem

Malfunction: Degraded rock quality, crownpillar and sill pillar failure fractured duringfreezing causes increased permeability ofrock mass increasing ground water capture,allowing high concentration arseniccontaminated water to reach mine pool.Additional water from thawing puts stress onplugs.

Release of arsenic contaminated water tomine pool and ultimately to watertreatment plant

5 A A C The freeze system will be repaired and re-established.In the event that this is not selected or is not possible,the Water Treatment Plant will be re-sized andoperated to accommodate the additional arsenicconcentration to prevent release of arsenic to theenvironment. Until additional plant components areconstructed that can process contaminated water toachieve compliant discharge water will be storedunderground.

A malfunction of the freeze system is likely only toaffect a single block. Monitoring of the frozen blocktemperatures and mine water quality will allow forearly detection and pinpointing of failure. It isassumed that thawing in such an event would be theresult of natural thawing, not from the intentionalapplication of heat to the frozen blocks.

High

WMS-26 Undergroundstorage

Storage Volume Mine inundation Accident: Flood from Baker Creek Accumulation of additional water in minepool. No release to the environment

4 A A B The volume of water treated through the watertreatment plant may temporarily increase to drawdown the mine pool water. Discharged water willremain compliant.

With the creation of the frozen block contact waterwill be eliminated.

High

WMS-27 Diffuser Thinner ice cover around diffuser Malfunction: Diffuser operation in a warmerwinter. Modelling does not accurately predictthe effect of discharge on ice cover

Safety issue for people utilizing areabecause ice is thinner than expected.

3 D A A Ice thickness around the diffuser location will bemonitored. The location of the diffuser will be markedto alert travelers of its location. If monitoring indicatesthat thinning of ice to unsafe levels is occurring fromthe diffuser discharge effluent will be cooled prior todischarge through longer retention in the settling andpolishing system.

Modelling taking into account the depth of thediffuser and the anticipated temperature of thedischarge water predicts that there will be no affecton ice thickness.

4 A A A High

WMS-28 Assimilation Capacity Detectable increase in arsenic thein receiving environment (BackBay)

Malfunction: Long term changes in lakeconditions and/or modeling inaccuracy.

Small incremental increase in arsenicconcentration in Back Bay

5 A B A No change in detectable arsenic levels in Back Bayarea expected due to the large assimilation capacity,however, ongoing monitoring will allow early detectionof any changes. Changes, if any would not show upfor decades and action to address such would likelyrequire a detailed level of assessment at that time todetermine options.

The execution of the remediation plan will reduce theamount of arsenic entering the environment fromcurrent levels.

High

WM-29 Discharge Regulations Water Remediation Criteriabecome more stringent

Malfunction: Regulatory changes, designcriteria become more stringent

Re-design and construct new WaterTreatment Plant.

3 A A C In the event of more stringent discharge criteria,expand/redesign the Water Treatment Plant to meetthe new criteria.

Design and operation of the plant will conform tochanges in regulations to maintain compliantdischarge as part of recapitalization.

4 A A B High

ReceivingEnvironment

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IS-1 Governance Governance Failures Malfunction: Competingmandates within INAC(regulatory and funding),between departments in GoC,territorial government (fundingand regulatory)

Slow reaction time to situationsconsequence is a project delay (3months)

3 A B C Project management systems,contingency funding, riskmanagement program, projectstructure, cooperation agreementb/w government, appropriate ERP,appropriate contracting, differentcontracting rules

Assumed that in the event of asignificant risk to humans or theenvironment, rapid action by thegovernment would take place. Alsoassumes contractor delay cost. Theperceived impacts may be higher.

4 A B C High

IS-2 Governance Governance Failure Malfunction: Lack of externalcommunication

Loss of regulatory support; Loss ofcredibility

2 A A A Additional activities and consultationwould be conducted

Moderate

IS-3 Governance Governance Failure Malfunction: Lack of oversightand monitoring

Confused roles and responsibilitieswithin the Remediation Team leadsto the temporary discharge ofinadequately treated water

4 A B B INAC's project management qualitycontrol / quality assurance is inplace; Independent engineerengaged

The scenario assumed is as worst case;The perceived impacts may be higher.

Moderate

IS-4 Governance Governance Failure Malfunction: Loss of politicalsupport for frozen block option

Lack of funding for freezecomponent requiring stabilizationand pump and treat

3 A A A Leads to substantial cost savings. Theperceived impacts may be higher.

Moderate

IS-5 Governance Governance Failure Malfunction: Inadequate trainingand emergency response

Primary consequence is dischargeof inadequately treated water intoBack Bay

3 A A A Ensure quality assurance program isin place (i.e. check training of staffand monitoring program)

Assumed short term perceived impactson the recreational use of Back Bay wasidentified; No drinking water impacts. ASurveillance Network Program would bein place.

Moderate

IS-6 Governance Governance Failure Malfunction: Loss of continuityand coordination

Loss of project knowledge 2 A A B Data control and mentoring ofpersonnel. Governance structurefirmly in place and is embedded inproject delivery.

3 A A B Moderate

IS-7 Regulatory Water Remediation Criteria becomemore stringent

Malfunction: Regulatorychanges

Plant expansion/redesign, additionalparameters to treat

4 A A C Ensure plant design is expandableand plant re-capitalization every 25years (treatment technologyimprovements incorporated intofuture plants)

Assumed that an existing plant is inplace, plant expansion / re-designrequired to meet new standards.

Moderate

IS-8 Governance Governance Failure Malfunction: Lack of externalcommunication

Loss of regulatory support; Loss ofcredibility

2 A A A Regular consultation and ongoinginvestment in communications

Moderate

IS-9 Governance Governance Failure Malfunction: Lack of oversightand monitoring

Confused roles and responsibilitieswithin the lead agencies lead to thetemporary discharge ofinadequately treated water

4 A B B Governance structure firmly in place;Ongoing monitoring and QA as perthe Water License; Plannedredundancy within the watertreatment process; Year-round watertreatment reduces concentration andflow rate

Moderate

IS-10 Governance Governance Failure Malfunction: Inappropriatefunding model for multi-yearproject

Funding cycle leads to inability todevelop long term contracts andhigh turnover of staff which resultsin upsets of treatment of non-compliant water

3 A A A Governance structure firmly in place;Ongoing monitoring and QA as perthe Water License; Plannedredundancy within the watertreatment process; Year-round watertreatment reduces concentration andflow rate

Short term, localized impacts that arereadily mitigated.

Moderate

IS-11 Governance Malfunction: Loss of continuityand coordination bymanagement

Operation and Maintenance andmonitoring commitments can nolonger be fulfilled; Leads to non-compliant discharge of a period ofapproximately 2 months

4 A B B Governance structure firmly in place;Ongoing monitoring and QA as perthe Water License; Plannedredundancy within the watertreatment process; Year-round watertreatment reduces concentration andflow rate

Assumed discharge into Back Bay notcaught due to monitoring no longeroccurring; Reporting to authorities on amonthly basis is a requirement.

Moderate

IS-12 Governance Remediated Mine Components Malfunction: End land usechanges

Additional remediation required 4 A B D Governance structure firmly in place;Ongoing monitoring and QA as perthe Water License

Assumed end change of land userequiring remediation causing localizedsite disturbance to establish ecosystem.

5 A B D Moderate

IS-13 Regulatory Water Remediation Criteria becomemore stringent

Malfunction: Regulatorychanges

Plant expansion/redesign, additionalparameters to treat

3 A A C Ensure plant design is expandableand plant re-capitalization every 25years (treatment technologyimprovements incorporated intofuture plants)

Assumed existing plant in place, plantexpansion / re-design required to meetnew standards.

4 A A C Moderate

Short Term

Long Term


Risk Scenario Event Sequences Chart: Institutional System

Confidence Estimate


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INF-1 Weather damage Accident: Extreme weather/highwinds

Strong wind exposes arsenic and friableasbestos

3 A A A Care and maintenance will continuefor this structure until demolition.During demolition work areas willbe contained or isolated.

Long term - all buildings will bedemolished which will eliminate therisks associated with this structure.Impacts may be perceived as higher.

Moderate


Strong wind results in building debrisblown towards highway with the potentialto injure.

4 C A A Care and maintenance will continuefor this structure until demolition.Impacts may be perceived as high.


High

INF-3 Earthquake Accident: Earthquake (max. 6.0magnitude for the region)

Building damage that exposescontaminants and complicates demolition.

5 A A B During demolition work areas willbe contained or isolated.


High

INF-4 Complcations encountered duringdemolition

Malfunction: Building removal failure Building damage 3 A A B This structure will bedecontamininated prior todemolition. Care and maintenancewill continue for this structure untildemolition. During demolition workareas will be contained or isolated.

Long term - all buildings will bedemolished which will eliminate therisks associated with this structure.

High


Collapses on Roaster 5 A A B During demolition work areas willbe contained or isolated.


High


Malfunction: Building removal failure Building damage 3 A A B During demolition work areas willbe contained or isolated.


High


Strong wind results in building debrisblown towards highway with the potentialto injure.

4 C A A This structure will bedecontamininated prior todemolition. Care and maintenancewill continue for this structure untildemolition. During demolition workareas will be contained or isolated.Cladding to be removed in 2011.


High


Asbestos cladding is disturbed andasbestos released into the air.

3 B B A During demolition work areas willbe contained or isolated.


High


Malfunction: Building removal failure Building damage 3 A A A During demolition work areas willbe contained or isolated.


High


Strong wind exposes friable Asbestos 3 A A A This structure will bedecontamininated prior todemolition. Care and maintenancewill continue for this structure untildemolition. During demolition workareas will be contained or isolated.


High


Malfunction: Building removal failure Building damage 3 A A A Care and maintenance will continuefor this structure until demolition.During demolition work areas willbe contained or isolated.


High


Strong wind results in building debrisblown towards highway and injures aperson

4 C A A This structure will bedecontamininated prior todemolition. Care and maintenancewill continue for this structure untildemolition. During demolition workareas will be contained or isolated.


High


Asbestos cladding is disturbed andasbestos released into the air

3 B B A Care and maintenance will continuefor this structure until demolition.During demolition work areas willbe contained or isolated.


High

Short TermBuildings

Stack

Roaster

C-Shaft Headframe

Mill

A-Shaft Headframe

FMECA - Giant Mine - Risk Assessment of Remediation ProgramRisk Scenario Event Sequences Chart: Infrastructure System

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FMECA - Giant Mine - Risk Assessment of Remediation ProgramRisk Scenario Event Sequences Chart: Infrastructure System

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Minor building damage 5 A A B During demolition work areas willbe contained or isolated.


High


Malfunction: Building removal failure Building damage 3 A A B Care and maintenance will continuefor this structure until demolition.During demolition work areas willbe contained or isolated.


High

INF-16 General Buildings Forest fire, large grass fire or otherlarge scale fire on site.

Accident: Lightning, human error Loss of C dry, WTP, freeze system andother structures

5 B B C Fire response plan for the site willbe maintained. The loss of theWTP and freeze system arecovered under failures on theWater Management and FreezeSystem Sheets.

Heat value of forest fire is low forarea, reasonable fire breaks betweenstructures currently existing exceptWTP. Arsene gas requires hightemperatures to ignite and thereforepresents little risk.

High

INF-17 UndergroundEquipment

Scoop Tram Underground Fire Accident: Accident leads to fire Loss of scoop tram or electrical systemsunderground

4 A A B Fire response plan for the site willbe maintained. In the event ofdamage, critical components will berepaired/replaced.

Any impact to the freeze program willbe short term.

High

INF-18 Tanks Fuel tank rupture and fire Malfunction and/or Accident: Collision or other accidentAccident leads to release and combustionof fuel

5 A B B Fire response plan for the site willbe maintained. Site controls suchas speed limits and barriers toprevent vehicle accidents will be inplace. Spills will be remediated.

Site controls and emergency planningare anticipated to minimise theoccurrence and consequence ofaccidents.

High

INF-19 Transportation Fuel spill on-site Malfunction: On-site accidentinvolving the transportation of fuel.

Contaminated soil and contaminatedwater, potentially affecting Baker Creek

4 A C C Site controls such as speed limitsand barriers to prevent vehicleaccidents will be in place. Spills willbe remediated. A spill responseemergency plan will be maintainedand spill response supplies will bestored on site.


High

INF-20 Mine WaterTreatment Plant

Reagent Storage On-site ferric sulphate spill Malfunction: On-site accident Contaminated soil and contaminatedwater, potentially affecting Baker Creek

4 A C C Site controls such as speed limitsand barriers to prevent vehicleaccidents will be in place. Spills willbe remediated. A spill responseemergency plan will be maintainedand spill response supplies will bestored on site.


High

INF-21 Buildings Freeze up of infrastructure, whichmay include Water Treatment Plant,and office complex and interruption infreeze operations

Accident: Site power failure Freeze up of infrastructure, which mayinclude Water Treatment Plant, and OfficeComplex; Interruption in freezeoperations. Details of consequences areaddressed under the Water ManagementSystem Sheet and Freeze System.

3 A A B Emergency response and recoveryplanning for key systems, includingthe installation of emergencygeneration capacity and protocolsfor Water Treatment Plant shutdown and restart. Details ofmeasures are addressed in theWater Management System andFreeze System .

Emergency response and recoveryplans and the addition of emergencygeneration capacity for key systemswill minimise the impacts of site powerfailure.

High

Long Term

Fuel Storage

B-14


Appendix CCascading Event Scenarios

Initiating Event Result FMECAReference

EarthquakeComponent Failure:Arsenic Crown Pillar

Failure

Pressure shock tobulkheads

ComponentFailure: Bulkhead

Failure

Arsenic solidsreleased to mine

pool

Increase in arsenicconcentration in minewater

ETP and MineWTP not designto high test water

Component Failure:ETP and Mine WTP

Failure

Increase in cost. Releaseto the environment.

UGS-3followed by

UGS-1

Earthquake Component Failure:Crown Pillar Failure

Crown pillarfailure leads to pitslope or pit wall

instability

Collapse underBaker Creek

Component Failure:Baker Creek

FailureBaker Creek flows into mine

Increase inarsenic

concentration inminewater

ETP and Mine WTPnot design to high

test water

ComponentFailure: ETP and

Mine WTP FailureRelease to the environment WMS-12

Earthquake

Component Failure:Baker Creek Failure

(base of creekcollapses)

Baker Creek flowsinto mine

Increase inarsenic


Minewater flooddamages

undergroundinfrastructure

Component Failure: Minedewatering pumps fail

Mine floods tosurface

Release to theenvironment. Baker Creek

Canal re-alignmentrequired. Underground

pumping systemreplacement required.

BCS-4

FloodComponent Failure:Baker Creek Bank

OverflowFlow into mine Rise in minewater

Increase in arsenicconcentration in

minewater

Component Failure:Underground instability (wet

conditions)

Release ofarsenic to mine

pool

ETP under designedto handle

concentration levels

New Mine WTPnot operational

yet

ComponentFailure: ETPtreatment not

effective

Impact to environment.BSC-1

followed byUGS-5

Giant Mine - Risk Assessment of Remediation ProgramCascading Event Scenario - Short Term (Implementation) - Table 1

Failure Sequence ----------->

C-1

Initiating Event Result FMECAReference

ExtremeWeather (GlobalWarming above

anticipatedlevels)

ComponentFailure: PassiveFreeze System

Failure

Thaw of frozen block UndergroundInstability

ComponentFailure: Sill Pillar

Failure

Release of arseniccontaminated water

to mine pool

Minewaterrequires more

treatment.

Mine WTPthroughputdecreases

ComponentFailure: MineWTP requires

upgrades

Increase cost WMS-24

Earthquake

ComponentFailure: BakerCreek Failure(base of creek

collapses)

Baker Creek flowsinto mine

Increase inarsenic


Minewater flooddamages

undergroundinfrastructure

ComponentFailure: Mine

dewatering pumpsfail

Mine floods tosurface

Non-compliant discharge to theenvironment. Baker Creek Canal re-alignment required. Underground

pumping system replacementrequired.

BCS-10

Giant Mine - Risk Assessment of Remediation ProgramCascading Event Scenario - Long Term (Post-Construction) Table 2

Failure Sequence -------------->

C-2


Appendix DMultiple Cause Scenarios

Multiple CauseScenarioNumber

Initiating Events Result FMECAReference

Effluent Treatment Plant(ETP) Supply of Chemicals

Interrupted (2 months)

Flood up to undergroundpumping system

Component Failure:Underground Pump Failure

Replace pumpingsystem

Failure of Baker Creek baseduring freshet Mine floods to surface New Mine WTP not

operational yetLoss of arsenic into

mine pool

ComponentFailure: ETP

Treatment notEffective

Wetting Plan for FreezeSystem Not Effective.Saturated Unfrozen in

Chambers

Component Failure: Re-designof Underground Stability

Program

Sill Pillar Failure

Component Failure: Loss ofarsenic into other portions of

the mine (previously non-arsenic containing) would

require a re-design of a portionof the freeze system

Giant Mine - Risk Assessment of Remediation ProgramMultiple Cause Scenario - Short Term (Implementation) - Table 3

Failure Sequence -------------->

Increase in costRelease to environment.

Increase in cost

MCS-1

MCS-2

ComponentFailure:

UndergroundStability Failure

Major loss ofarsenic

slurry intomine

BCS-4

UGS-5

Component Failure: ETPwould require upgrades or

additional temporarytreatment would be requiredto treat the elevated arsenic

in minewater.

ComponentFailure: BakerCreek Base

Collapse

Flood intomine

D-1

MultipleCause

ScenarioNumber

Initiating Events Result FMECAReference

New Mine Water Treatment Plant(Mine WTP) is down for annualgeneral maintenance (1 week)

Flood up tounderground

pumping system

Component Failure:Underground Pump

Failure

Replace pumpingsystem

Extreme weather causes a floodevent over the designed capacity ofBaker Creek and a power outage

Flood up to frozenarsenic chambers

Arsenic residue lost intominewater

Nominal increaseconcentration of

arsenic inminewater

Snow and ice of tailings cover meltscreating higher then normal run-off

Greater than anticipatedconsolidation occurs on tailings

cover

Loss of Long Term Power

Passive Freeze System Failure

Mine WTP (on back-up power) increases

treatment rateIncrease in cost FS-8

SS-11

MCS-3

ComponentFailure: BakerCreek Bank

Overflow

Flood into mine

MCS-4

ComponentFailure: Tailings

Cover(Geotextile) Fails

Run-off does notmigrate off-site No impact

MCS-5Component

Failure: PassiveFreeze System

Degraded rock quality Crown and sill pillarfailure

Increase arsenic loadingto minewater

Giant Mine - Risk Assessment of Remediation ProgramMultiple Cause Scenario - Long Term (Post-Construction) - Table 4

Failure Sequence ------------>

Increase in costNo impact to Mine

WTPBCS-6, WMS-23

D-2


Appendix EList of Participants for Workshops

E-1

Workshop 1:

i. March 22 to 24, 2011 in Vancouverii. Participants:

INAC INAC -Ben Nordahn Department of Justice – Carla Conkin

PWGSC PWGSC – Henry Westermann, P.Eng. PWGSC - Corrine Stokowski PWGSC - Norm Quail PWGSC - David Abernathy PWGSC - Desmond O’Connor PWGSC - Doug Townson, NWTAA, B.Arch. PWGSC - Lisa Dyer, P.Eng. PWGSC - Mark Cronk, P.Eng.

DXB Projects DXB Projects - Dave Bynski, P.Eng, PMP

AECOM AECOM - Robert Boon, P.Eng. AECOM - David Knapik, P.Eng. AECOM - Rudy Schmidtke, M.Sc, P.Eng. AECOM - Jennifer Singbeil, P.Eng.

Golder Golder - John Hull, P.Eng. Golder - Cameron Clayton, M.Eng, P.Geo. Golder - Darren Kennard, P.Eng.(BC) Golder - David Caughill, P.Eng. Golder - Katharine Harrison Golder - Randa Salameh Golder - Richard Beddoes, P.Eng. Golder - Nathan Schmidt, Ph.D., P.Eng.

Workshop 2:

i. April 4 to 6, 2011 in Vancouverii. Participants:

INAC INAC –Michael Nahir, M.Eng., P.Eng. INAC - Martin Gavin, P.Eng. INAC - Adrian Paradis Department of Justice – Carla Conkin Government of the Northwest Territories (GNWT) – Ken Hall Brodie Consultants Ltd. – John Brodie, P.Eng. SRK Consulting (SRK) – Daryl Hockley, P.Eng.; Peter Mikes, P.Eng. SENES – Bruce Halbert

E-2

PWGSC PWGSC - Henry Westermann, P.Eng. PWGSC - Corrine Stokowski PWGSC - Norm Quail PWGSC - David Abernathy PWGSC - Desmond O’Connor PWGSC - Lisa Dyer, P.Eng. PWGSC - Mark Cronk, P.Eng. PWGSC - Chris Doupe PWGSC - Sharon Nelson

DXB Projects DXB Project - Dave Bynski, P.Eng., PMP

AECOM AECOM - David Knapik, P.Eng. AECOM - Rudy Schmidtke, M.Sc, P.Eng. AECOM - Gordon Woollett, P.Eng. AECOM - Barry Williamson, P.Eng.

Golder Golder –.John Hull, P.Eng. Golder - Ross Hammet, P.Eng. Golder - Richard Beddoes, P.Eng. Golder - David Caughill, P.Eng. Golder - Katharine Harrison Golder - Brian Griffin, B.A.Sc Golder - Nathan Schmidt, Ph.D., P.Eng.

Workshop 3:

i. May 30 and 31, 2011 in Edmontonii. Participants:

INAC INAC –Michael Nahir, M.Eng., P.Eng. Brodie Consultants Ltd. – John Brodie, P.Eng.

PWGSC Norm Quail Mark Cronk, P.Eng.

DXB Projects DXB Projects - Dave Bynski, P.Eng., PMP

Golder Golder - John Hull, P.Eng. Golder - Darren Kennard, P.Eng. (BC)

E-3

AECOM AECOM - Rudy Schmidtke, M.Sc, P.Eng. AECOM - David Knapik, P.Eng. AECOM - Jennifer Singbeil, P.Eng. AECOM - Jillian Roth, EIT AECOM - Larissa Wall

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