dmp_tailingsstoragefacilitiesinwa

7/30/2019 DMP_TailingsStorageFacilitiesInWA

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DRAFT for public comment

CODE OF PRACTICE


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DRAFT Tailings storage facilities in Western Australia Page 2 of 24

Foreword

Basis for code of practice

This code of practice is issued by Resources Safety under the Mines Safety and Inspection

Act 1994, with the endorsement of the Mining Industry Advisory Committee (MIAC) and

approval from the Minister for Mines and Petroleum.

A code of practice is a practical guide to achieving the standards of occupational safety and

health required under legislation. It applies to anyone who has a duty of care in the

circumstances described in the code. In most cases, following a code of practice would

achieve compliance with the duties in the legislation in relation to the subject matter of the

code. However, like regulations, codes of practice deal with particular issues and do not

cover all hazards or risks that may arise. Duty holders need to consider all risks associated

with work, not only those for which regulations and codes of practice exist.

Codes of practice are admissible in court proceedings. Courts may regard a code of practice

as evidence of what is known about a hazard, risk or control and may rely on the code in

determining what is reasonably practicable in the circumstances to which the code relates.

Compliance with the legislation may be achieved by following another method, such as a

technical or an industry standard, if it provides an equivalent or higher standard of work

health and safety than the code.

An inspector may refer to an approved code of practice when issuing an improvement or

prohibition notice.

Scope and application

This code is a practical guide to assist those involved in designing, constructing, operating

and decommissioning tailings storage facilities (TSFs) to meet their legislative obligations.

Tailing storage facilities are reservoirs that store mine tailings, which is fine-grained waste

material in suspension that is discharged from an ore processing plant or coal preparation

plant. A TSF includes associated starter dams, erosion protection bunds, levee banks,

diversion channels, and seepage collection trenches, pits, dams and ponds.

This code does not apply to waste dumps, heap or vat leaching facilities, or underground

mine fill.

Who should use this code?

You should use this code if you have functions and responsibilities for designing,

constructing, operating, managing or rehabilitating TSFs. The code may also be used by

supervisors, TSF personnel, and safety and health representatives who need to understand

the hazards associated with constructing and operating TSFs.


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How to use this code of practice

The code includes references to bot mandatory and non- mandatory actions.

The words must or requires indicate that legal requirements exist, which must be

complied with. The word should indicates a recommended course of action, while may

indicates an optional course of action.


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Contents

Foreword ............................................................................................................................. 2Part 1 Introduction ........................................................................................................... 51 Introduction .................................................................................................................... 5

1.1 Aims ....................................................................................................................... 51.2 Structure of code .................................................................................................... 51.3 Roles of competent persons ................................................................................... 61.4 Further information .................................................................................................. 6

2 Information, instruction, training and supervision............................................................ 72.1 Introduction ............................................................................................................. 72.2 Information .............................................................................................................. 72.3 Instruction ............................................................................................................... 72.4 Training ................................................................................................................... 82.5 Supervision ............................................................................................................. 8

Part 2 Classification of TSFs ........................................................................................ 103 Hazard-based approach ............................................................................................... 10

3.1 Introduction ........................................................................................................... 103.2 Hazard ratings ...................................................................................................... 123.3 Classification ......................................................................................................... 12

Part 3 Requirements ...................................................................................................... 164 Site selection ............................................................................................................... 165 Design ......................................................................................................................... 17

5.1 Design needs ........................................................................................................ 175.2 Design factors ....................................................................................................... 175.3 Design submission ................................................................................................ 19

6 Construction ................................................................................................................. 206.1 Construction plan .................................................................................................. 206.2 Construction report submission ............................................................................. 20

7 Operation ..................................................................................................................... 217.1 Operations, monitoring and maintenance manual ................................................. 217.2 Operational record ................................................................................................ 217.3 Operational audits and reviews ............................................................................. 21

8 Emergency preparedness and plan.............................................................................. 239 Closure ........................................................................................................................ 24

9.1 Planning for closure .............................................................................................. 249.2 Decommissioning review ...................................................................................... 24


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Part 1 Introduction

1 Introduction

1.1 Aims

The aims of this code of practice are to describe:

a set of outcomes for tailings storage facilities (TSFs) to meet the approval requirements

of the project management plan under the Mines Safety and Inspection Act 1994 and

Mines Safety and Inspections Regulations 1995, and the mining proposal under the

Mining Act 1978

the variables to be considered to demonstrate that a TSF is safe and stable the recommended hazard management process for TSFs

the broader occupational health and safety requirements for operating in accordance

with the Mines Safety and Inspection Act 1994and Mines Safety and Inspections

Regulations 1995.

The code promotes a proactive approach to monitoring during construction, operation, and

prior to closure so it is possible to predict a TSFs long-term performance and potential

environmental impact after closure.

1.2 Structure of codePart 1 introduces the code of practice and summarises the requirements for information,

instruction, training and supervision to ensure the occupational safety and health of TSF and

other affected personnel.

Part 2 describes how a TSFs hazard rating, embankment height and location determine its

classification. The level of TSF management needs to be commensurate with the potential

impact of TSF failure or loss of integrity.

Part 3 is structured to support a hazard management approach for TSFs that follows the life

cycle of a TSF, including:

site selection

design

construction

operation

emergency planning

closure.


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1.3 Roles of competent persons

To assure a safe and stable TSF at the end of the life cycle, competent persons should:

certify the design

certify construction meets design specifications and tolerances

ensure discharge materials are within design tolerances

ensure performance is within operational tolerances

provide training and assess competency of TSF workers

conduct audits and reviews.

1.4 Further information

Guidance on how to achieve the outcomes described in this code is available from:

The Australian National Committee on Large Dams Inc. (ANCOLD),www.ancold.org.au International Commission on Large Dams (ICOLD),www.icold-cibg.org

Specific guidance on handling tailings that potentially contain radionuclides is available from:

International Atomic Energy Agency (IAEA),www.iaea.org
http://www.ancold.org.au/http://www.ancold.org.au/http://www.ancold.org.au/http://www.icold-cibg.org/http://www.icold-cibg.org/http://www.icold-cibg.org/http://www.iaea.org/http://www.iaea.org/http://www.iaea.org/http://www.iaea.org/http://www.icold-cibg.org/http://www.ancold.org.au/


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2 Information, instruction, training and supervision

2.1 Introduction

The provision of information, instruction, training and supervision is an essential component

of safe systems of work. The following sections describe what this means in practical terms

for a TSF so personnel can undertake tasks safely and avoid harm to health.

2.2 Information

Personnel must have the information necessary to complete tasks safely. This may include:

manuals provided by original equipment manufacturers (OEMs)

the operations policies, procedures and plans

applicable legislation, Australian and industry standards, and other guidance material.

2.3 Instruction

Personnel must be instructed about specific tasks to be undertaken, including the hazards

and risks, the controls to be applied, and the job steps necessary to complete the tasks

safely.

Instructional tools such as job safety or hazard analyses (JSAs or JHAs), safe work

instructions or procedures (SWIs or SWPs) and standard operating procedures (SOPs) may

be used to document the process, but should be reviewed and amended if equipment or

conditions change.

Instructions must be approved by the supervisor or management.


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2.4 Training

People must be competent in the tasks they are assigned. This means they must have the

knowledge and skills necessary to perform the task safely. Competency is gained through

training and experience while being supervised or mentored.

The risk management training provided must be appropriate to the assigned roles and

responsibilities. It must provide information on:

the risk management process

task-specific safe work methods, including the safe use of tools and equipment and safe

systems of work.

The effectiveness of training can be increased by using case studies, or examples, from

mining workplaces to demonstrate risk management principles for specific hazards.

Assessment of competency should be evidence based and verified before work commences.

Competency may be verified:

by recognition of prior learning (RPL)

by on-site recognition or validation of current competency (RCC or VOC)

via the operations training and development program.

All verification methods must include a documented assessment. There must also be a

system to ensure affected personnel are consulted, retrained and reassessed whenever

systems of work or plant and equipment change, or new systems of work or plant and

equipment are introduced.

2.5 Supervision

Supervisors are responsible for the quantity and quality of the output of others and contribute

to the development of technical solutions to non-routine problems. Supervision of TSFs

includes managing assigned work areas and crews, communicating regularly with others,

diagnosing and solving routine and non- routine problems, controlling work programs to

ensure objectives are met, and maintaining operating records.

Supervisors ensure a safe workplace by:

confirming that workers are trained and competent for the task undertaken

providing clear work instructions

inspecting and monitoring workplace conditions

continuously evaluating worker performance and correcting unsafe acts

reporting and rectifying hazards

assuring implementation of the companys safety systems

demanding compliance with safety rules and procedures.

Effective supervisors spend most of their time in the workplace engaged with the workforce

and conducting meaningful observations, consultation and interventions.


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Moving into a supervisory or team leader role involves the application of a range of new

skills. Much of the additional responsibility comes down to managing people, and to do this

successfully requires a comprehensive range of workplace communication skills. Information

about resources to assist in the transition of operators to supervisory or team leader roles is

available atwww.skillsdmc.com.au
http://www.skillsdmc.com.au/http://www.skillsdmc.com.au/http://www.skillsdmc.com.au/http://www.skillsdmc.com.au/


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Part 2 Classification of TSFs

3 Hazard-based approach

3.1 Introduction

The primary function of a TSF is the safe and economical storage of tailings in an erosion-

resistant, non-polluting structure that minimises environmental impacts.

TSFs need to be individually tailored to the site, ore mineralogy, the plant process, and

desired long-term landform and therefore will have a variety of designs and construction

techniques. The design approach, construction method and decommissioning concept

should be selected to suit the local conditions.

Above-ground TSFs

In an above-ground facility, tailings are generally stored behind a purpose built embankment.

The embankment can be constructed to its designed maximum height in several stages or in

one pass. In common with conventional water storage dams, the control of seepage waters

from TSFs is important to maintain stability. However, the purpose-built tailings storage

embankments differ significantly from water storage dams in a number of important aspects,

including those described below.

The design life of a TSF is normally considered to be perpetuity. A TSF could beconsidered to have two phases in its life a depositional phase with active human

involvement followed by an unending erosion free, environmentally benign stage with no

further human intervention.

Rehabilitation aspects require careful consideration, as TSFs cannot be breached at the

end of their service to allow the containment area or valley to return to its original

condition. Instead, material and liquids or leachate must remain safely stored.

The materials stored behind the embankment may be loose or poorly consolidated with

some contained water. Contaminants of varying toxicity may also be contained within the

impounded material. Under severe seismic shock, saturated tailings can liquefy to

produce a mobile fluid of high unit weight, leading to additional loading on the

embankment.

Some containing embankments are constructed by hydraulic deposition, rather than

mechanised placement.

Many TSFs are developed progressively as part of a mining operation; they can be

constructed in stages, over a period of years, with the embankment being raised to keep

pace with tailings production. Their staged development allows performance reviews

which enables a more flexible approach compared with conventional water storage

dams. However, this design flexibility may, to a certain degree, be offset by a generally

lower standard of construction control than is the case for water storage dams.

TSFs can be raised by upstream and centreline methods.

A well designed, constructed and operated TSF can achieve a significant drawdown of


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the phreatic surface in the tailings material near the embankment. As tailings deposition

continues, with embankment raising, the embankment can derive a significant amount of

structural support from the tailings material.

The presence of materials that could contaminate the downstream environment (e.g.

sulphide minerals generating acidic leachate, heavy metals) should be recognised andmanaged in an environmentally appropriate manner.

Tailings may also stored with waste rock in the same facility.Co-storage requires careful

consideration of a number of factors, including the available void volume in the waste rock

material; the relative proportions of waste rock, tailings solids and tailings fluids; and the

strength of the waste rock material and its resistance to compaction and consolidation with a

consequent reduction in void volume.

Below-ground (in-pit) TSFs

Direct storage in previously mined-out open pits or underground openings below the naturalground level is an alternative method for tailings storage used by some mine operators. In

practice, this approach is more difficult to manage than above-ground storage due to

difficulties with the removal of contained fluid, and the resultant low densities of deposited

materials. These challenges mean that approval to adopt below-ground storage will usually

require extensive geotechnical, hydrogeological and environmental studies to establish the

viability and long-term safety of below-ground storage of tailings.

Below-ground storage should only be considered when:

there is no possibility of a potentially viable mineral resource being sterilised by the

deposition rehabilitation measures are provided to ensure that there is no long-term environmental

impact or public safety hazard

there is no possibility that safety in any operating underground mines in the vicinity will

be jeopardised by the proposed TSF

future underground mining beneath the stored tailings is not contemplated or likely.

The main difficulty with in-pit storage is the rapid rate of rise of tailings level in the early

phases of deposition. This is when the pit is deepest and the exposed surface area is

smallest, with a consequent reduction in the effect of solar drying and desiccation on a given

volume of tailings compared with typical above-ground TSFs of the same overall capacity.

Water management in these circumstances can be very difficult, and methods should be

considered to increase water recovery, or extract water and thicken the tailings slurry before

deposition.


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3.2 Hazard ratings

The hazard rating assigned to an individual TSF will be high, significant or low. The rating is

not an assessment of the risk of failure, but rather the potential impact of any of the following

scenarios:

controlled or uncontrolled escape of tailings material or liquor

seepage of tailings liquor

overflow or leakage of tailings liquor

an abrupt failure of the tailings retention embankment.

Depending on the public facilities and mining infrastructure located close to the TSF, a

dambreak study should be completed to show the impact of a failure of the embankment.

The scope of the study should determine the extent, travel times and velocities of potential

flooding or tailings flow slides, and any safety, health and environmental effects on the

downstream area. The dambreak study should investigate the case of worst-case floodlevels being contained in the TSF at the maximum design tailings storage level.

Since the hazard rating is a function of the potential impact, a well designed and constructed

embankment, or a well-operated TSF, may still receive a high or significant hazard rating.

The hazard rating is derived for the whole life of the TSF (including future raises) by

considering the potential impact of the scenarios on:

the safety and health of people

the environment

any property infrastructure

mining developments (including those of the TSF operator).

Table 1 shows the hazard rating system that applies to TSFs in Western Australia.

Note: For TSFs with no embankments, only Part I of Table 1 should be used. However, there

may be exceptions. For example, for an in-pit TSF located adjacent to an operating open-pit

mine separated by a narrow land bridge or waste dump, Part II of Table 1 is applicable, with

the land bridge and waste dump treated as an embankment.

3.3 Classification

Hazard rating, embankment height and location are used to classify TSFs in Western

Australia. To maintain a consistent approach to hazard identification and management under

this code, above-ground TSFs are classified as a Category 1, 2 or 3 facility based on the

TSFs hazard rating and embankment height (Table 2). In-pit TSFs comprise the fourth

class.

A TSFs classification will determine the degree of investigation, design input, construction

supervision, and ongoing assessment and review necessary to assure it is safe and stable at

the end of its life cycle.


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Where the TSF is used to store wastes potentially containing radionuclides, the facilitys

management must also be consistent with the applicable safety standards of the

International Atomic Energy Agency (IAEA).

Category 1 TSFCategory 1 TSFs have the highest potential for extensive loss of life and other health

impacts, loss of stock and environmental damage in the event of failure.

Note: Cross-valley TSFs or those that block or significantly impede flow in natural drainage

lines should be treated as Category 1 TSFs, regardless of the embankment height.

Category 2 TSF

In the event of failure, Category 2 TSFs have a lower potential impact than Category 1 TSFs.

Category 3 TSFCategory 3 TSFs have the lowest potential impact in the event of failure.

In-pit TSF

In-pit TSFs typically have the lowest potential for surface degradation because it is unlikely

that the TSF would fail, but there is the potential for inadvertent access and environmental

damage through groundwater contamination.

Note: Some in-pit TSFs are converted to above-ground TSFs by constructing a perimeter

embankment away from the edge of the pit. In this case, the above-ground TSF classification

should be applied. For central thickened discharge facilities and dry stacked tailings, themaximum stack height may be used instead of the maximum embankment height.

Table 1 Hazard rating system applicable to TSFs in Western Australia

Type of effect

Hazard rating

High Significant Low

Part I: Controlled or uncontrolled release or seepage

Adverse healtheffects

Location is such thatchemical

contamination ofwater likely to beused for humanconsumption andconsumption of thecontaminated waterare expected

Location is lesscritical but

contamination ofwater likely to beused for humanconsumption andconsumption of thecontaminated waterare possible althoughnot expected

No contamination ofwater likely to be

used for humanconsumption

is expected


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Type of effect

Hazard rating


Location is such that

radioactivecontamination ofresidential orhabitable areas isexpected

Location is less

critical buyradioactivecontamination ofresidential orhabitable of areas ispossible

No radioactive

contamination ofresidential orhabitable area isexpected

Loss of stock Location is such thatcontamination ofwater likely to beused for stockconsumption andconsumption of the

contaminated waterare expected

Location is lesscritical butcontamination ofwater likely to beused for stockconsumption and

consumption of thecontaminated waterare possible althoughnot expected

No contamination ofwater likelyto be used for stockconsumption isexpected

Environment damage Location is such thatdamage to anenvironmentallysignificant feature isexpected

Environment featureis less significant ordamage is possiblebut not expected

No significantdamage toenvironmentalfeatures is expected

Part II: Embarkment failure (assessment is based on dambreak study)

Loss of human life Loss of life isexpected because ofcommunity or othersignificantdevelopment

No loss of lifeexpected but thepossibility isrecognised

No urbandevelopment and nomore than a smallnumber of habitablestructuresdownstream

No loss of life isexpected

Adverse healtheffects

Chemicalcontaminationresulting in healthhazards or loss ofresidential orhabitable areas isexpected

Short term (< 3months) chemicalcontamination ofresidential orhabitable areas ispossible

No contamination isexpected


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Type of effect

Hazard rating


Radioactive

contaminationresulting in healthhazards or loss ofresidential orhabitable areas isexpected

Short term (< 3

months) chemicalcontamination ofresidential orhabitable areas ispossible

No radioactive

contamination isexpected

Excessive economicloss is expected,such as seriousdamage tocommunities,industrial,commercial oragriculture

facilities, mineinfrastructure, thestorage itself or otherstoragesdownstream

Appreciableeconomic loss ispossible, such asdamage tosecondary roads,minor railways,relatively importantpublic

utilities, mineinfrastructure, thestorage itself or otherstoragesdownstream

No significanteconomic loss isexpected, withlimited damage toagricultural land,minor roads andmine infrastructure

Storage essential forservices and repairsis not practicable

Repairs to storageare practicable

Repairs to storageare practicable andindirect losses arenot significant

Table 2 Matrix of hazard ratings and height used to classify above-ground TSFs in Western

Australia

Maximumembarkment height

Hazard rating


> 15 m Category 1 Category 1 Category 1

5 - 15 m Category 1 Category 2 Category 2

< 5 m Category 1 Category 2 Category 3


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Part 3 Requirements

4 Site selectionThe site for a TSF should be selected with regard for the impact of the facility on the

surrounding infrastructure and environment, particularly in the event of seepage, dust

generation, chemical or particulate exposure, erosion, overtopping or an abrupt embankment

failure, either during operations or after closure.

Factors that affect site selection include:

hydrology (e.g. potential for flooding, catchment area characteristics)

topography (e.g. influence of watershed, streams and creek systems)

surrounding area (e.g. proximity to public infrastructure, centres of population,operational mine sites, camps and areas of environmental significance)

foundation material (e.g. water tightness, strength, liquefaction potential)

construction materials (e.g. suitability, availability, proximity)

climate (e.g. rainfall patterns, evaporation rates, prevailing winds)

proposed construction methods (e.g. upstream, centreline and downstream raising).


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5 Design

5.1 Design needs

The objective of the design process is to achieve a design where the risk of failure or

damage to the TSF is remote. The TSF design needs to demonstrate facility integrity and

safety during:

normal operation

abnormal operation (e.g. decant pump failure, pipe breakouts)

extreme events (e.g. seismic loading, extreme weather)

post-closure.

The design must satisfy the safety requirements of section 9 of the Mines Safety and

Inspection Act 1994, the environmental requirements of the Mining Act 1978andEnvironmental Protection Act 1986, and other State and national legislation as applicable.

5.2 Design factors

The following criteria influence the design of a TSF and their assessment should be

documented during the design and construction phases:

hazard classification

site conditions

geology (e.g. bedrock, structure)

geomorphology

foundation conditions (e.g. physical, geochemical and geotechnical properties)

hydrogeology

terrain

climate

seismicity

surface hydrology (e.g. drainage patterns, flood volumes)

minimum freeboard

decant pond design

characteristics of tailings and construction materials (e.g. physical, geochemical and

geotechnical properties)

seepage control measures

availability of suitable construction material

construction method (e.g. upstream, centreline and downstream raising)

embankment stability, erosion resistance, and resistance to dynamic or static liquefaction

instrumentation and monitoring

operating method

requirements for access

characteristics and availability of capping materials

closure requirements.


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Note: When considering the option of an upstream raising to a TSF, there are increased

risks associated with potential liquefaction of constituent materials. Suitable screening

criteria should be applied to determine whether further quantitative evaluation of the

liquefaction potential is required.

5.3 Design submission

A competent person should:

certify that the design achieves the occupational safety and health, and environmental

outcomes required under applicable legislation

specify the:

ongoing design verification and validation methods

construction, operational and maintenance principles

closure plan.


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6 Construction

6.1 Construction plan

The mine operator should develop and implement a construction plan with quality assurance

procedures to ensure that the TSF construction meets design specifications and tolerances.

6.2 Construction report submission

A competent person should certify that the TSF meets design specifications and tolerances

and prepare a report that:

documents the conditions encountered during construction and verifies them against

those assumed in the design

includes a non-compliance report with documented remedial measures if the conditionsencountered did not meet the original design or specifications

includes a variance report if the construction was required to deviate from the original

design

demonstrates that the testing and measurement regime was appropriate and sufficient to

validate the design parameters

includes survey drawings of the TSF showing the true positions of features such as

borrow pits, embankments, drains, monitoring instrumentation, decant towers, and buried

pipework and cables (see Resources Safetys Mines survey code of practice, published

in 2011).


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7 Operation

7.1 Operations, monitoring and maintenance manual

A competent person should develop and maintain an operating manual for TSF operators

that provides:

documented procedures for the safe and efficient storage of tailings in line with the

assumptions and principles adopted by the designer

documented processes that comply with legislation and public expectations, and can be

used as a reference during auditing of the facility.

The operational manual should be current and contain:

deposition and operational methods

instrumentation, monitoring and inspection requirements, and schedules

maintenance requirements and schedules

ongoing verification requirements and schedules

audit criteria and schedules

an operational stage risk register

health and safety, quality, environmental and training plans

trigger action response plans

emergency response plans.

rehabilitation plans and schedules

legislated criteria.

7.2 Operational record

A TSF is monitored to provide a measure of actual performance against expected

performance as described in the mining proposal for the project. As well as conventional

environmental monitoring for dust, gases and water, it is recommended that the following

aspects are recorded:

tailings densities

tailings properties

inflow volumes storage volumes

deposition time remaining.

The TSFs performance during significant seasonal events should also be recorded.

7.3 Operational audits and reviews

A competent person should prepare a TSF review program that includes auditing and

ongoing verification activities in accordance with the design specifications and regulatory

requirements.


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The audits and reviews should be conducted by a competent person. The type and level of

information provided in audit and review reports should be commensurate with the TSFs

hazard rating and classification. Matters expected to be addressed in reports include:

current survey plan of the facility showing spot elevations along walls and across tailingsbeaches where possible

reconciliation of stored volume and calculated densities with expected values from the

mining proposal; an assessment of available capacity remaining in terms of volume and

time

assessment of deposited tailings properties

water balance studies with an approximate reconciliation of slurry volumes, solids

content, decant recovery, site rainfall and evaporation

validation of TSF design, using input parameters derived from site measurements and

testing; implications for future of the facility if present trends are continued

recommendations for any necessary operational or design modifications monitoring results and analysis; proposals for additional monitoring of identified problem

areas; implications of monitoring results (e.g. changed management practices or new

works) and proposals for any necessary seepage recovery systems problems, failures

and successes, and any alterations to the facility or operations that are proposed

overview of any wall lifts completed since the last audit or review, how they were built,

and any lifts proposed for the coming year.

A record of audit and review outcomes should be maintained by the mine operator, including

any actions recommended in the audit or review, and details of how they were addressed or

implemented.


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8 Emergency preparedness and plan

A TSF emergency action plan should be developed and maintained in line with the mines

emergency response plan, and be kept as part of the TSFs operating procedures. It should

contain:

assignment of responsibilities

information relating to any warning or emergency alarm systems

description of the emergency procedures

It should address potential emergency scenarios such as burst pipelines and those identified

in the dambreak study.

The TSF emergency action plan should:

be written in plain English

be compiled and laid out to facilitate quick access to important information

include appropriate use of illustrations such as maps

be available to all affected personnel on site.

The plan should be regularly tested to ensure its effectiveness. Both desk-top tests and

emergency response drills involving onsite personnel should be carried out. Evacuation drills

can be used to evaluate how people respond.

Debriefings conducted as soon as practicable after an emergency or drill will help identify

modifications needed to improve the TSF emergency action plan.


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9 Closure

9.1 Planning for closure

As TSFs are a critical closure issue, the TSF closure plan must be developed in line with the

overall mine closure plan required under the Mining Act 1978. This plan will begin as a

conceptual plan at the design stage, becoming more detailed during the operation of the

mine as it accommodates relevant operational change, new regulations and new technology.

The initial TSF design should include ongoing survey, monitoring and instrumentation so that

some post-closure assumptions can be verified prior to closure, or data obtained to increase

the reliability of post-closure performance predictions.

The mine closure plan should also consider premature or temporary closure of the TSF due

to unplanned suspension of mining operations.

9.2 Decommissioning review

Before the cessation of a TSF, a competent person should assess the facility and prepare a

report that includes:

a review of the status of the structure and its contained tailings

updated site plans

an examination of the implications of the physical and chemical characteristics of the

materials and remediation measures if required

a review of the results of all monitoring validation of the TSF design for long-term stability

the proposed rehabilitation stabilisation works

long-term flood management strategies.

There will be time after TSF decommissioning, and before closure, when continued

monitoring is required to assure a safe and stable landform as per the design intent.

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