Paper+ +March+2002+

Tailings Management Discussion Paper - March 2002 v3

DEPARTMENT OFNATURAL RESOURCES & ENVIRONMENT

DISCUSSION PAPERTAILINGS STORAGE

GUIDELINES FOR VICTORIA

Department of Natural Resources & Environment - Victoria

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FOREWORD

A number of serious incidents at mines in Europe and other parts of the world in recent years

have alerted communities and the mining industry to the risks associated with storage and

handling of mine tailings. Victoria’s record in the management of mine tailings is good.

Significant incidents involving the accidental release of mine tailings or other impacts

associated with their management have been rare. Nevertheless, this is not a reason for

complacency.

Improvements in storage design, equipment and techniques for tailings management have all

lead to a significant improvement in industry performance in this area over the last 2 decades.

Public policy and legislation for protection of the environment has also developed rapidly in

recent years, moving from a stance that was essentially regulatory to one where industry is

expected to take responsibility for defining goals and managing it’s own performance. The

mining and extractive industries are also now keenly interested in improving the perception of

their industries as responsible partners in sustainable development.

In recognition of these developments and the increasing role of mining in the economy of the

State, the Department proposes to develop new regulatory guidelines for the management of

tailings storage facilities in Victoria. This discussion paper is the first step in that process.

NRE is seeking stakeholder views on the issues raised by the discussion paper and on any

other matters readers consider relevant to the development of the new guidelines. Comments

are especially sought from individuals or organisations with a particular interest or expertise

in mine waste management, environmental protection or water management.

Comments or submissions on this discussion paper should be submitted to NRE by 1 July

2002 and directed to:

Environmental ManagerMinerals & Petroleum RegulationDepartment of Natural Resources & EnvironmentPO Box 500EAST MELBOURNE VIC 3002Or email: [email protected]

RICHARD ALDOUSExecutive DirectorEnergy and Minerals


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TABLE OF CONTENTS

SECTION PAGEFOREWORD ................................ ................................ ................................ ................................ .... I

EXECUTIVE SUMMARY ................................ ................................ ................................ .............. 1

1 INTRODUCTION ................................ ................................ ................................ ...................... 4

2 STRUCTURE OF REPORT ................................ ................................ ................................ ...... 6

PART 13 TAILINGS HANDLING AND STORAGE................................ ................................ ................ 8

3.1 Introduction................................ ................................ ................................ ............ 8

3.2 Characterisation of Tailings ................................ ................................ .................... 9

3.2.1 Classification According to Minerals Extracted ................................ .......... 9

3.2.2 Chemical characteristics ................................ ................................ ............. 9

3.2.3 Physical characteristic s................................ ................................ ............. 10

3.3 Surface Disposal ................................ ................................ ................................ ... 10

3.3.1 Hydraulic Discharge (Conventional TSF) ................................ ................. 10

3.3.2 Paste ................................ ................................ ................................ ........ 14

3.3.3 Central Thickened Discharge (CTD) ................................ ........................ 15

3.4 In-Pit Disposal ................................ ................................ ................................ ...... 15

3.5 Underground Disposal (Backfill) ................................ ................................ .......... 16

3.6 Co-Disposal ................................ ................................ ................................ .......... 16

3.7 Deep Sea Tailings Placement ................................ ................................ ................ 17

3.8 Selection of Disposal Option................................ ................................ ................. 17

4 POTENTIAL ENVIRONMENTAL IMPACTS OF TSF................................ ......................... 18

5 MANAGEMENT OPTIONS ................................ ................................ ................................ .... 21

5.1 Introduction................................ ................................ ................................ .......... 21

5.2 Risk Management................................ ................................ ................................ . 21

5.3 Waste Minimisation................................ ................................ .............................. 24

5.4 Cyanide Management ................................ ................................ ........................... 26

5.5 Site Selection................................ ................................ ................................ ........ 27

5.6 Community Participation ................................ ................................ ...................... 28

5.7 TSF Design ................................ ................................ ................................ .......... 28

5.7.1 Wall Type ................................ ................................ ................................ 28

5.7.2 Water Recovery................................ ................................ ........................ 30

5.7.3 Permeability of the enclosure................................ ................................ .... 31


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5.7.4 Design Approval ................................ ................................ ...................... 31

5.8 Construction ................................ ................................ ................................ ......... 32

5.9 Operation................................ ................................ ................................ .............. 33

5.9.1 Water Management and Tailings Deposition................................ ............. 34

5.9.2 Environmental Monitoring/Transfer Reporting ................................ ......... 35

5.9.3 Maintenance /Pipelines and Tailings Handling Equipment........................ 36

5.9.4 Emergency Preparedness/Incident Reporting ................................ ............ 37

5.10 Decommissioning................................ ................................ ................................ . 38

5.10.1 Planning for Closure................................ ................................ ................. 38

5.10.2 Cover Design & Revegetation ................................ ................................ .. 38

5.10.3 Maintenance/ Long Term Management................................ ..................... 39

PART 2

6 VICTORIAN GEOGRAPHY, CLIMATE AND MINING ACTIVITIES............................... 42

6.1 Physiography................................ ................................ ................................ ........ 42

6.2 Climate................................ ................................ ................................ ................. 42

6.3 Mining................................ ................................ ................................ .................. 43

6.4 Extractive Industries ................................ ................................ ............................. 43

7 VICTORIAN LEGISLATION AND POLICY ................................ ................................ ........ 44

7.1 Government Policy Framework ................................ ................................ ............ 44

7.2 Mining Legislation ................................ ................................ ............................... 44

7.3 Extractive Industry Legislation ................................ ................................ ............. 45

7.4 Environment Protection Act, Regulations, Policy & Guidelines ............................ 45

7.5 Other Environmental Legislation ................................ ................................ .......... 47

7.6 NRE Information Sheets ................................ ................................ ....................... 48

7.7 NRE Requirements for the Work Plan................................ ................................ ... 49

8 INTERNATIONAL MINING GUIDELINES, CODES AND STANDARDS .......................... 51

8.1 North America................................ ................................ ................................ ...... 51

8.1.1 Canada................................ ................................ ................................ ..... 51

8.1.2 USA................................ ................................ ................................ ......... 53

8.2 South America................................ ................................ ................................ ...... 54

8.2.1 Peru ................................ ................................ ................................ ......... 54

8.2.2 Mexico................................ ................................ ................................ ..... 57

8.3 Asia................................ ................................ ................................ ...................... 57


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8.3.1 China ................................ ................................ ................................ ....... 57

8.3.2 Malaysia ................................ ................................ ................................ .. 58

8.4 South Africa ................................ ................................ ................................ ......... 59

8.5 Europe................................ ................................ ................................ .................. 60

8.5.1 United Kingdom (UK)................................ ................................ .............. 60

8.5.2 Other EC Countries ................................ ................................ .................. 61

8.6 ICOLD Tailings Dam Guidelines................................ ................................ .......... 61

9 AUSTRALIAN MINING GUIDELINES, CODES AND STANDARDS ................................ . 64

9.1 Western Australia ................................ ................................ ................................ . 64

9.2 Queensland................................ ................................ ................................ ........... 65

9.3 New South Wales ................................ ................................ ................................ . 67

9.4 South Australia ................................ ................................ ................................ ..... 68

9.5 Tasmania................................ ................................ ................................ .............. 68

9.6 Northern Territory ................................ ................................ ................................ 69

9.7 Nuclear Waste Guidelines................................ ................................ ..................... 69

9.8 ANCOLD Tailings Guidelines................................ ................................ .............. 70

9.9 Environment Australia (Commonwealth) – Best Practice EnvironmentalManagement in Mining................................ ................................ .................... 71

10 BIBLIOGRAPHY................................ ................................ ................................ ..................... 74

10.1 Guidelines, Codes and Accepted Good Practice ................................ .................... 74

10.2 Papers and Books ................................ ................................ ................................ . 77

LIST OF FIGURES

Figure No. 1 - Various Methods of Raising TSF Perimeter Embankments

Figure No.2 - Symbolic Representation of Influence of Development Control andOperational Management on Long Term Risks

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EXECUTIVE SUMMARY

Introduction

Management of tailings is the biggest environmental issue currently facing the miningindustry. This is especially true of the gold mining sector where tailings often containcyanide. The industry has recognised this situation and industry bodies both in Australia andoverseas have initiated work to improve industry standards for tailings management.

The June 2000 Ministerial statement “Pillars for Balanced Growth” commits the VictorianGovernment to developing a minerals industry that meets contemporary communityexpectations for social and environmental outcomes. This discussion paper and proposeddevelopment of guidelines builds on the industry initiatives described above and is consideredto be an important step towards achieving the aims of Government policy.

The Department of Natural Resources and the Environment (NRE) proposes to developguidelines to cover all aspects of tailings storage within Victoria, including Departmentaladministration. The aims of the NRE project are to prepare:• A detailed literature review• A discussion paper• Procedural guidelines for the approval of the safe design, construction, use and closure of

tailings storage facilitiesThis document represents the conclusion of the first two of these steps.

Background

The study and development of tailings engineering was mainly initiated in the 1970’s. Thegrowth of environmental awareness around the world in the last three decades has resulted ina significant tightening in the regulatory framework for mining and the disposal of miningwastes. Research and practice has reflected these concerns and the 1980’s and 1990’s hasseen considerable advances on Tailings Storage Facility (TSF) issues such as theminimisation of environmental impacts, probabilistic analysis of stability, the effects ofseismic events and rehabilitation.

Tailings that are generated in Australia generally fall into one of seven broad sub-categories:• Base metal tailings that are generally fine grained, and may have a significant clay

content. These tailings commonly also have a high acid generating potential.• Gold tailings that have been subjected to a cyanidation process, and may be acid

generating.• Uranium tailings that are radioactive and contain a high percentage of chemical

precipitates (gypsum and metal hydroxides).• Coal tailings that usually have two components: a coarse reject and a washery fines,

which may be disposed of separately or may be combined. They are sometimes both acidgenerating.

• Nickel Tailings that have been subjected to high temperature and pressure leaching,followed by neutralisation, that influence the material properties.

• Alumina Red Mud tailings that have a high alkalinity.• All other types, including potash tailings, phosphate tailings, clay tailings (or “slimes”).

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The three most common adverse characteristics of deposited tailings in Victoria are likely tobe:• Remnant cyanide.• Sulphur-rich minerals (such as iron pyrite) leading to the potential for acid generation

through oxidation.• High salinity of pore water.

Tailings is usually transported to, and discharged into, a TSF as a slurry. Once delivered tothe TSF, the slurry may be deposited below water ( subaqueously) or above water(subaerially) on the natural ground surface or on a tailings beach. Other deposition techniquesinvolve the use of pastes, central thickened discharge underground disposal or in-pit disposal.Tailings can also be deposited in conjunction with waste rock or other materials , a techniquereferred to as co-disposal.

There are numerous approaches to the containment and storage of tailings around the world.For above ground storage, these can normally be divided into two categories:• Cross-valley storage , whereby a dam wall is constructed across a natural valley to contain

the tailings and associated water.• Off-valley storage, which can be located on land ranging from near-horizontal to a gentle

valley side slope.Irrespective of the selected category, there are several options available for the formation ofthe retaining embankment(s)

Potential causes of impacts on the environment from a TSF fall into the following broadcategories.• Structural failures• Operational failures• Equipment failures• Unforseen consequences

The following are considered to be the most serious potential impacts resulting from theoperation of a TSF.• Risk to human life• Pollution of surface waters• Inundation of vegetation with sediment• Pollution of ground waters• Increased ground water levels resulting in surface salinity• Fauna mortality• Generation of Dust

Management Options

The purpose of this section of the discussion paper is to raise a range of issues for comment. Itis hoped that this will stimulate discussion and assist readers to formulate their response.Respondents are encouraged to make comment on any issue they consider relevant to theregulation of tailings storages in Victoria. In particular a number of matters for comment arehighlighted in boxes throughout the section.

Matters addressed include:• Risk management,• Waste minimisation,• Cyanide management,

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• Site selection,• Community participation,• TSF design,• Construction,• Operation, and• Decommissioning

A range of approaches to the management of tailings storage has been adopted around theworld. Design guidelines vary appreciably in response to jurisdictional legislation, specificgeomorphology and climate constraints, and historical experience.

It is the Department’s aim to develop an objective based system that is reliant whereverpossible on self regulation by industry. It is recognised however, that all regulatory systemsneed to have the confidence of the community and it is expected that there will be a numberof key areas of concern where prescriptive measures are necessary to reassure the communitythat risks have been addressed. It is also clear that for any self regulatory measures to beacceptable, they must be subject to periodical audit by the Department or other independentexperts.

Structure of the Report

Part 1 of the report includes Sections 3 to 5 which discuss current practice in tailingsmanagement, the potential impacts and options for regulation of these activities. Section 5 inparticular raises a number of issues for discussion or comment.

Part 2 comprises Sections 6 to 9 of the report and includes description of the Victorianenvironment and legislative context and summaries of the Australian and international tailingsmanagement documentation that has been reviewed in preparing this report.

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1 INTRODUCTION

Management of tailings is the biggest environmental issue currently facing the mining

industry. This is especially true of the gold mining sector where tailings often contain

cyanide. The industry has recognised this situation and industry bodies both in Australia and

overseas have initiated work to improve industry standards for tailings management. The

Minerals Council of Australia introduced a policy on tailings management last year which

commits it and it’s members to development of solutions to the environmental, social and

health issues associated with tailings management. In addition industry is participating with

Governments in a joint working group to develop a Strategic Framework for Tailings

Management. Internationally, industry groups have been strongly supportive of initiatives

such as the United Nations Environment Program projects to develop a Cyanide Management

Code . The Global Mining Initiative, an industry based project to develop measures for

sustainability in the minerals sector may also have some consequences for tailings

management.

The June 2000 Ministerial statement “Pillars for Balanced Growth” commits the Victorian

Government to developing a minerals industry that meets contemporary community

expectations for social and environmental outcomes. The Ministerial Statement also refers to

the need to provide a framework to enable industry to develop and achieve appropriate

economic, social and environmental outcomes within an acceptable level of community risk.

This discussion paper and proposed development of guidelines builds on the industry

initiatives described above and is considered to be an important step towards achieving the

aims of Government policy.

The State of Victoria currently has no specific guidelines that cover the design, construction,

operation, decommissioning and rehabilitation of tailings storage facilities (TSF). The

Department of Natural Resources and the Environment (NRE) have therefore decided to

develop guidelines to cover all aspects of tailings storage within Victoria, including

Departmental administration. The aims of the NRE project are to prepare:

• A detailed literature review of tailings information from all Australian States and

Territories and overseas countries, with emphasis on existing guidelines and policies,

significant developments and existing technical papers.

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• A discussion paper setting out regulatory and technical issues that could be disseminated

to industry and the community for comment.

• Procedural guidelines for the approval of the safe design, construction, use and closure of

tailings storage facilities. The guideline is to include objectives and good practice

principles and take into account the comments received on the discussion paper.

This document represents the conclusion of the first two of these steps.

NRE policies regarding the disposal of mining and extractive industry wastes include

commitments to:

§ Ensuring the safety of TSF both during its operating life and after closure.

§ Requiring the minimisation of waste generation and encouraging the recycling of wastes.

§ Managing and reducing environmental pollution.

§ Requiring the rehabilitation and revegetation of mining and extractive industry TSF to

minimise long term risks to the environment.

The key policy objectives influencing the preparation of the guidelines are:

§ Promotion of environmental responsibility – failure to accept responsibility can lead to

risks and costs to the community which reduce or even exceed the benefits of the original

exploitation of the resource, and

§ Ensuring the safety of facilities – this implies that the facility should possess an inherent

degree of safety. This safety margin can be reduced by climatic events, geotechnical

instability, poor design, poor operational practice or management, adverse environmental

impacts or inadequate access controls. The evaluation of safety is site-specific although

minimum criteria should always be satisfied.

NB In Victoria, distinct Acts and Regulations govern the mining and extractive industries,

although the administrative requirements and process are reasonably similar. Whilst the

discussion paper and guidelines focus on mine tailings, NRE intend that the resultant

guidelines also be used by the extractive industry, where applicable.

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2 STRUCTURE OF REPORT

This report has the following structure:

Part 1 includes Sections 3 to 5 which discuss current practice in tailings management, the

potential impacts and options for regulation of these activities. Section 5 in particular raises a

number of issues for discussion or comment.

Part 2 comprises Sections 6 to 9 of the report and includes description of the Victorian

environment and legislative context and summaries of the Australian and international tailings

management documentation that has been reviewed in preparing this report.

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DISCUSSION PAPER:

TAILINGS STORAGE


Part 1

Tailings Management, Impacts andOptions

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3 TAILINGS HANDLING AND STORAGE

3.1 Introduction

Prior to the mid 1970’s there was little dedicated engineering applied to the design of tailings

dams. Where considered necessary, the general principles of geotechnical engineering,

agricultural engineering, hydraulics and earth fill dam engineering were applied. In general,

however, most structures were developed on the basis of experience and a general desire to

keep TSF development costs to a minimum. At that time there were few environmental

control requirements that influenced the design and development of a TSF.

An awareness of the need for tailings engineering was highlighted in 1968 when the Aberfan

(UK) coal tip failure focussed attention on the methods of disposal of coal wastes (including

tailings). In the 1970’s, the catastrophic TSF failures at Buffalo Creek (1972, Virginia, USA),

killing 125 people and Bafokeng (1974, Transvaal, South Africa), killing 12 underground

miners, further highlighted a need for appropriate engineering and control. The need for clear

TSF design guidelines in this regard was emphasised in the 1980’s after a number of

seismically-induced failures of large TSF in South America and the loss of 268 lives due to

failure of the TSF at Prealpi Mineraia mine in Stava, Italy. More recently, accidental tailings

releases at Marinduque Island in the Phillipines in 1996, near Seville in Spain in 1998 and at

Baia Mare in Romainia in January 2000 have caused serious harm to the environment.

The study and development of tailings engineering was mainly initiated in the 1970’s. At that

time, there were few reference works specific to tailings and practicing engineers developed

innovative methods through the 1970’s and 1980’s to facilitate the design of tailings storage

facilities. These methods and the general approach to the design and management of TSF are

still commonly employed today. The growth of environmental awareness around the world in

the last three decades has resulted in a significant tightening in the regulatory framework for

mining and the disposal of mining wastes. Research and practice has reflected these concerns

and the 1980’s and 1990’s has seen considerable advances on TSF issues such as the

minimisation of environmental impacts, probabilistic analysis of stability, the effects of

seismic events and rehabilitation. The mining industry is increasingly applying asset

management principles to TSF siting and operation and is addressing mechanisms to handle

the long-term liabilities associated with these facilities.

March 2002 9


Currently accepted good practice in TSF design, development, operation, management and

rehabilitation incorporates significantly more rigorous analysis, interpretation and control

than was accepted (or even possible) 20 years ago. Moreover, there have been several

innovative developments in tailings engineering since the mid 1990’s that should be

considered when developing a guideline document for the purpose of TSF regulation. These

developments are briefly discussed in the following sections.

3.2 Characterisation of Tailings

3.2.1 Classification According to Minerals Extracted

Tailings that are generated in Australia generally fall into one of seven broad sub-categories:

• Base metal tailings that are generally fine grained, and may have a significant clay

content. These tailings commonly also have a high acid generating potential.

• Gold tailings that have been subjected to a cyanidation process, and may be acid

generating.

• Uranium tailings that are radioactive and contain a high percentage of chemical

precipitates (gypsum and metal hydroxides).

• Coal tailings that usually have two components: a coarse reject and a washery fines,

which may be disposed of separately or may be combined. They are sometimes both acid

generating.

• Nickel Tailings that have been subjected to high temperature and pressure leaching,

followed by neutralisation, that influence the material properties.

• Alumina Red Mud tailings that have a high alkalinity.

• All other types, including potash tailings, phosphate tailings, clay tailings (or “slimes”).

3.2.2 Chemical characteristics

Tailings are chemically similar to the parent ore, but the presence of process reagents,

weathering after deposition and evaporation of water may significantly change their

March 2002 10


properties. All tailings have been subjected in some way to a physical and/or chemical

separation processes (eg flotation, cyanidation, acid leaching). Constituents of environmental

concern may therefore be present in a TSF, particularly in the pore fluid, including a variety

of metals, chemicals, salts and radioactive materials.

In arid regions the process water may also be saline or hypersaline, posing an additional threat

to the environment.

The three most common adverse characteristics of deposited tailings in Victoria are likely to

be:

• Remnant cyanide.

• Sulphur-rich minerals (such as iron pyrite) leading to the potential for acid generationthrough oxidation.

• High salinity of pore water.

3.2.3 Physical characteristics

Tailings produced from mining and quarrying activities is generally composed of natural rock

and soil particles that behave in a manner that conforms to the principles of soil mechanics.

As such, the shape of the particle size distribution curve, coupled with knowledge of the

particle specific gravity and mineralogical information, normally allows for reasonable

estimates to be made of beach geometry, settling behaviour, settled dry density, shear strength

and permeability. Nevertheless, all tailings behave somewhat differently from each other, and

there is invariably a need to carry our specific tests on each material to obtain sufficient

confidence in anticipated physical behaviour prior to completing a TSF design.

3.3 Surface Disposal

3.3.1 Hydraulic Discharge (Conventional TSF)

Tailings is usually transported to, and discharged into, a TSF as a slurry. The solids

concentration of the slurry (and hence rheological behaviour) will depend on a number of

factors including the distance to be pumped, the type of process, process plant throughput

rate, and several other factors. Nevertheless, despite some variability in performance, this

March 2002 11


method of hydraulic transport and placement of tailings remains the favoured approach,

primarily due to its ease of operation.

Once delivered to the TSF, the slurry may be deposited below water ( subaqueously) or above

water (subaerially) on the natural ground surface or on a tailings beach. Subaqueous

deposition is normally only used in applications where the water is used to inhibit acid

generation due to oxidation or dust generation. Subaqueous deposition may, however, be

practically unavoidable during the early stages of TSF development when the ground

topography results in low areas adjacent to the point of discharge. This situation is quickly

overcome through mounding of the tailings into a beach, and the formation of a supernatant

pond away from the outer wall of the TSF.

It is important to achieve subaerial deposition as soon as possible, as subaqueously deposited

tailings rarely achieves the dry density that can be anticipated from subaerially deposited

material. Moreover, the consolidation of subaqueously deposited tailings is normally very

slow and it is impracticable to use the tailings to raise the outer wall of the TSF. It is also

improbable that an upstream method of wall construction can be adopted (see below) due to

the need to design the outer wall as a water retaining structure.

Subaerial deposition of tailings slurry is the method of discharge that will usually be used in

Victoria.

There are numerous approaches to the containment and storage of tailings around the world.

For above ground storage, these can normally be divided into two categories:

• Cross-valley storage , whereby a dam wall is constructed across a natural valley to contain

the tailings and associated water. The principal advantage of this approach is that

relatively little earthworks is required in relation to the volume of the embankment

required to contain the material. The main disadvantages are that a river diversion is

required, initial capital costs, risks of flow failure and environmental impacts may be high

and substantial spillways may be required.

• Off-valley storage, which can be located on land ranging from near-horizontal to a gentle

valley side slope. This approach requires the construction of confining embankments,

either on the downhill side(s) or around the full perimeter to form an impoundment. The

advantages of this approach over a cross-valley storage are that runoff management is

simpler and groundwater impacts are likely to be lower.

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Within the above categories, there is a multitude of variations that are commonly adopted,

and in some instances a combination of cross-valley and side-valley configurations can be

adopted. In Australia, the off-valley storage option is preferred for environmental reasons.

Moreover, the cross-valley option is not often technically viable due to the flat nature of the

terrain that is typical of many mine sites.

Irrespective of the selected category, there are several options available for the formation of

the retaining embankment(s) as symbolically indicated on Figure 1.

Figure 1: Various Methods of Raising TSF Perimeter Embankments

(after Chamber of Mines of South Africa, 1996)

Embankment raises are formed from either imported fill or from desiccated tailings, sourced

from the adjacent beach.

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• Single stage embankment construction to full height. This option is usually adopted for

facilities of relatively low height (less than 5 m), where sufficient capital is available, or

where it is impracticable to effect future raises.

• Downstream raising of the embankment(s), whereby the embankment crest moves

progressively downstream, or outwards from the stored tailings. In some countries it is

mandatory to adopt this technique due to seismic loading conditions. It is by far the most

expensive means of raising the embankment due to the large volume of material required

to form the embankment.

• Upstream raising of the embankment(s), whereby the embankment crest moves

progressively upstream, or partially over previously deposited tailings. This method is

usually the least expensive option, but necessitates careful consideration of the stability

and potential for settlement, as well as the practicability of construction and the potential

for seepage. It is a system commonly (and safely) employed in arid/semi-arid

environments that have low seismic activity, such as prevails over large tracts of

Australia.

• Centreline raising of the embankment(s), whereby the embankment crest remains in the

same plan location as the embankment is raised. This system is a compromise between

upstream and downstream techniques, offering some of the advantages of each. It is

usually used in situations where the stability of the embankment would not be adequate

under an upstream raise condition.

All of the above methods can be used together, in a variety of combinations and some

relatively elaborate schemes have been developed to minimise costs whilst maintaining an

acceptable level of risk. Each situation needs to be considered on its own merits, taking into

consideration the factors that influence the stability of the embankment. This is frequently

also influenced by the type of water decant system that is utilised.

There are three broad categories of decant systems employed on tailings storage facilities:

• Spillways, as commonly used on water dams. These may necessitate ponding of water

close to the embankment, which may require centreline or downstream raises to be

adopted.

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• Pump systems, either from a floating pontoon arrangement, or from a fixed structure

located on natural ground or on a dedicated central embankment. These systems are high

maintenance items, but are commonly used in Australia to return water directly to the

plant, due to the practice of storing water on the surface of the TSF, rather than in a

separate water holding dam.

• Gravity decants, comprising an inlet tower formed from precast rings, timber slats, planks

or similar that may facilitate regulation of flow from the pond into an outlet pipe that

allows decanted water to flow to an external collection point. This system is common in

Australia, and is normally accompanied by a filter zone formed from waste rock around

the inlet. This assists in maintaining the decanted water at the required low turbidity

level.

3.3.2 Paste

Paste is a dense, low slump, viscous mixture of tailings and water. It does not segregate when

it stops flowing and exudes very little supernatant water when deposited. A low solids

concentration slurry is thickened to a paste using either a deep cone thickener, or a

combination of conventional thickener and a filter press.

Paste is known as dry stacking in the alumina red mud disposal industry.

Full tailings paste may be used to construct a surface TSF and potentially offers the following

significant advantages over slurry tailings disposal:

• Reduced Slurry Water: In a dry climate where water conservation is a priority, the

additional water recovered during the thickening of the tailings to a paste is beneficial. In

wet climates water management is simplified. Because the tailings does not release

water, seepage of water from the TSF is minimised.

• Modification of Tailings Properties: Cement may be added to the paste to improve its

shear strength, to immobilise toxic or radioactive tailings, to increase the static and

dynamic stability of the TSF and to inhibit wind erosion. Bentonite may be added to

create a seepage barrier or liner or to decrease the permeability of the tailings mass.

The cost savings and environmental advantages offered by paste will probably be the major

motivators for the implementation of paste disposal system. The most compelling reasons for

March 2002 15


its use will probably be to conserve water in extremely dry climates and to immobilise toxic

or radioactive substances. The paste process also enhances rehabilitation in most cases.

3.3.3 Central Thickened Discharge (CTD)

When thickened tailings is deposited sub-aerially from one or more discharge points that are

strategically located near to the centre of the TSF footprint, the tailings beach develops a

uniform gradient over most of its length and creates a stack with an essentially conical shape.

The relatively flat conical landform created by a CTD is often similar to the natural

topography. The tailings surface is erosion resistant and readily rehabilitated. Virtually all

the supernatant water is lost to evaporation and decant facilities are normally only required to

manage run-off. When the rate of rise of the deposit is low, evaporative drying assists the

tailings to desiccate and achieve a high density and shear strength.

The main disadvantage of the system is the large area covered by the TSF and hence the

greater amount of land that is influenced by the tailings system.

3.4 In-Pit Disposal

In some circumstances an environmentally attractive and low cost option is to deposit tailings

into mined out open cut workings. There are, however, several potential problems associated

with this approach which include:

• The pits are frequently deep and have a relatively small surface area. This results in sub-

aqueous deposition of the tailings leading to poor consolidation and low strength, which

makes rehabilitation of the surface difficult. Large long-term settlement needs to be

accounted for in the rehabilitation planning.

• A high phreatic surface is typically generated in the tailings, which may lead to

contamination of groundwater around and under the pit. Because the tailings is placed

below the water surface it is difficult to intercept and remediate seepage to groundwater.

• There may be a risk posed to the stability of current mining areas, coupled with a

possibility of ingress of liquefied tailings into adjacent underground workings. In the

extreme case there may be a collapse with a concomitant inrush of material having

catastrophic consequences, as occurred at Mufilira copper mine in Zambia (1970).

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3.5 Underground Disposal (Backfill)

Tailings have been placed in underground workings since the 1800’s. In recent years

significant advances have been made in backfilling of mining stopes with tailings. Typically,

tailings may be placed underground as:

• Backfill : Deslimed or classified, sand sized tailings, placed hydraulically as a slurry. The

backfill may be placed with or without the addition of a binder, most often cement.

• Paste : Total tailings thickened to a paste consistency, generally deposited with the

addition of a binder to provide early strength gains.

The use of backfill underground has numerous well documented benefits including improved

roof support, reduction of catastrophic stress relief (rock bursts), improvement of ventilation

in underground workings to address heat problems at depth, reduction of barrier pillar

requirements, minimisation of water ingress and reduction in the potential for underground

fires.

There is considerable scope for the use of cemented full tailings paste as backfill in mines,

particularly in high stress environments. Paste backfill also offers significant advantages to

bulk mining operations where it allows present long wall production rates to be achieved

more reliably from many smaller stopes.

3.6 Co-Disposal

Co-disposal involves the mixing of coarse and fine waste streams to reduce the costs of waste

disposal. In coal mines it is possible to pump the coarse and fine wastes together, while in

metalliferous mines the coarse waste has to be hauled. Co-disposal reduces the total air space

required for waste disposal, while at the same time improving the drainage properties and

hence increasing the rate of consolidation and strength gain of the fines. The following

approaches may be adopted:

• Coarse waste worked into previously placed fine waste.

• Fine waste worked into previously placed coarse waste.

• Coarse and fine waste blended and the mixture placed.

There are frequently significant problems associated with controlling the deposition strategy

to achieve optimum mixing of coarse and fine materials. Generally co-disposal is only

March 2002 17


economic where either the two products can be pumped together or dumped simultaneously

into a pit.

3.7 Deep Sea Tailings Placement

A tailings slurry can be deposited via a submerged pipeline below the surface of the sea, into

a sufficiently deep location. This is called Deep Sea Tailings Placement (DSTP) 1. Tailings is

deposited via an engineered outfall pipeline to a depth and location that is selected to

discharge below the biologically productive near-surface layer and where there is minimal

risk of tailings solids rising to the surface.

Currently the London Convention on the Disposal of Waste at Sea (1996) allows DSTP for

tailings, although it is expected that the latest revision will close this allowance. Article 1 of

the Convention Protocol indicates that the disposal of waste derived from exploitation and

off-shore processing of sea bed mineral resources is not covered by the Protocol. This

implies that tailings from processing sea bed minerals could be returned to the ocean. Annex

2 emphasises the need to progressively reduce disposal of waste to the sea by requiring

proponents to carry out waste prevention audits and consider a range of waste minimisation

strategies.

Dumping of wastes into the sea in Australia is governed by the Environment Protection (Sea

Dumping) Act 1981. In 1998 the Australian and New Zealand Environment and

Conservation Council (ANZECC) issued the document “Interim Ocean Disposal Guidelines”

which provide a framework to assess the environmental impact of dredge spoil or excavated

material. Annex 1 contains a list of materials which may be considered for dumping and

whilst not specifically mentioning tailings, the list includes “inert, inorganic geological

material”. Despite some possible advantages, the potential for DSTP in Australia is

considered to be low (Jones (1996)).

3.8 Selection of Disposal Option

The selection of which disposal option is most appropriate for a particular site and waste

material should be made by evaluating the engineering characteristics of the site against the

waste material characteristics, legislation/policies and community requirements. Ideally this

process should result in the selection of an option which addresses the requirements of all

stakeholders, the operator, the government, and the community.

1 Sometimes referred to as Submarine Tailings Disposal (STD).

March 2002 18


4 POTENTIAL ENVIRONMENTAL IMPACTS OF TSF

Like many industrial facilities, mines and the associated tailings management activities

impose some level of risk on their surroundings. The design, location and standard of

operation of a TSF can have a significant effect on the risks associated with the facility. The

goal of Government and responsible operators alike is to reduce those risks to acceptable

levels and to manage residual risks appropriately.

Potential causes of impacts on the environment from a TSF fall into the following broad

categories.

• Structural failures – these are cases generally involving the collapse, subsidence or

slippage of a part of a containment structure such as a dam wall. Such failures can give

rise to the discharge of large quantities of tailings and treatment solutions and lead tovery

severe environmental damage as a result. In extreme cases such events can threaten

human life due to inundation or damage inflicted on structures.

• Operational failures – in these cases the root cause of the incident is the failure to

operate or control the operation of a facility adequately. For example, failure to monitor

the water level of a TSF could result in an overflow. Lack of adequate operational control

can ultimately result in a structural failure. For example, if water levels were allowed to

rise to the point of overflow, the dam wall could then be eroded and fail.

• Equipment failures – Wherever mechanical equipment such as pipelines, pumps, valves

etc used for tailings management activities there is potential for mechanical failure. Burst

pipelines, coupling breakage and pump failure are common causes of accidental

discharge. Failures of the kind are not usually as serious as those due to operational or

structural causes but can nevertheless cause significant harm to the environment.

• Unforseen consequences – Some instances of damage to the environment are the result

of simple oversight in the design, operational procedures or closure of a TSF. For

example, the long term consequences of slow seepage from the base of a TSF may not

have been adequately considered at design stage and may not become apparent for some

years.

March 2002 19


The following are considered to be the most serious potential impacts resulting from the

operation of a TSF.

• Risk to human life – Historically there have been a number of cases internationally

where failure of major tailings structures has resulted in loss of life either as a result of

inundation of downstream communities or where mine workings have been flooded. The

likelihood of public fatalities in Victoria is thought to be remote at present due to the

smaller size of tailings storage facilities and the low density of habitation near TSF’s.

However, the potential for such incidents should be considered in any future

developments.

• Pollution of surface waters – Effects on streams and watercourses can arise from a

number of factors in TSF operation. Accidental discharge can of course result in

contamination of receiving waters with process solutions such as cyanide or with high

loads of sediment. Acidification of sulphitic tailings and subsequent seepage can result in

trace metal contamination. Failures of ancillary equipment such as pipelines can also

result in the escape of tailings and reagents. Erosion of a closed TSF can cause high

offsite sediment loads. The resulting impacts can vary depending on the type of tailings

and reagents involved. For example, cyanide solutions discharged to a stream may have a

very serious initial impact but be rapidly degraded and have no long term effect. A

discharge containing high levels of toxic metals would however, be much more likely to

have permanent or very long term impacts.

• Inundation of vegetation with sediment – Where large volumes of tailings have escaped

as a result of a serious failure, the resulting sediment load can be so high that the

receiving watercourse is blanketed with tailings material. In cases where this has occurred

the result has been a high degree of impact on the existing aquatic and riparian flora and

fauna. The resulting clean up can be extremely expensive and challenging – if possible.

• Pollution of ground waters – Many TSF’s can be considered to be “controlled

attenuation” structures. This means that they are designed to restrict the seepage of

contained solutions rather than completely contain them. This approach has the advantage

that the contained material in a TSF will slowly dry and increase it’s mechanical strength.

This should not compromise ground water quality provided appropriate design parameters

have been used. However, there is a risk that where toxic reagents are used or where the

tailings material itself is inherently enriched in a toxic element there will be an

unintended impact as a result of seepage. Such an impact can also occur where a facility

March 2002 20


designed to be totally contained develops a leak or where the design or construction

quality assurance was not sufficiently rigorous. Leakage can occur as a result of faulting

or fractures in the substrate of a structure or where the load imposed by the TSF causes

subsidence or slippage.

• Increased ground water levels resulting in surface salinity – The increased pore

pressures associated with seepage from a TSF and resulting from the mass loading of a

large body of tailings can result in localised increases in ground water levels. In sever

cases this can lead to saline scalding or ground water discharge.

• Fauna mortality – Terrestrial fauna have been seriously effected by some TSF’s. Birds

in particular have been killed in large numbers in a couple of well known incidents

involving cyanide tailings in other States. The risk of such effects is greatly heightened

where cyanide levels are not managed carefully or where drought or arid conditions

restricts access to other water supplies. While these incidents are not common, the effects

can be very serious and must be considered when planning a TSF.

• Dust – Tailings must often be allowed to dry for long periods prior to covering and

rehabilitation. There is a resultant risk that, especially in drier climates, the surface

material will be subject to wind erosion. Dust from tailings impoundments can be a

serious nuisance for nearby residents and can have detrimental impacts on the quality of

rainwater collected for drinking purposes.

March 2002 21


5 MANAGEMENT OPTIONS

5.1 Introduction

Victoria has an opportunity to develop a system of regulation of tailings storage facilities that

will ensure the implementation of current standards of best practice in environmental

protection and reduction of risk to the community. It is the Department’s aim to develop an

objective based system that is reliant wherever possible on self regulation by industry. It is

recognised however, that all regulatory systems need to have the confidence of the

community and it is expected that there will be a number of key areas of concern where

prescriptive measures are necessary to reassure the community that risks have been addressed.

It is also clear that for any self regulatory measures to be acceptable, they must be subject to

periodical audit by the Department or other independent experts.

The purpose of this section of the discussion paper is to raise a range of issues for comment. It

is hoped that this will stimulate discussion and assist readers to formulate their response. The

absence of any particular issue from this section should not be taken to imply that it is not to

be considered. Respondents are encouraged to make comment on any issue they consider

relevant to the regulation of tailings storages in Victoria.

5.2 Risk Management

It is evident that a range of approaches to the management of tailings storage has been

adopted around the world. Design guidelines vary appreciably in response to jurisdictional

legislation, specific geomorphology and climate constraints, and historical experience. For

example, the upstream method of construction of TSF is banned in Chile, cyanide treatment is

banned in Montana, and in some US states it is mandatory for a liner to underlie all TSF.

Some countries, such as China, impose stringent requirements upon the design and operation

of TSF, whereas Western Australia allows for flexibility in the design and operation, whilst

recommending that “best practice” principles be adopted in general.

Figure 2 attempts to demonstrate the variety of approaches that can be considered when

developing a management control system.

March 2002 22


Figure 2:

Influence of Development Control and Operational Management on Long Term Risks(after Williams DA, 1999)

Referring to Figure 2, it can be seen that:

• Control on the development of a TSF (second column from left) can be influenced to

varying degrees, according to the country (or state within a country) that the TSF is to be

developed. This is symbolised by the arbitrary scale from 1 to 10, ranging from

“uncontrolled” development, through to Acts of parliament. Most countries/states can be

considered to exert a current level of control between “3” and “8”.

• The degree of development control will directly influence the TSF development costs

(left hand column), from a level that can be considered to be “reasonable”, through

“marginal” to “high”.

• The right hand column represents the risk that the TSF will not meet the long-term

expectations of the public during operation and after closure. Examples of such risks are

release of an unacceptable amount of dust, generation of acid leachate or downstream

vegetation mortality.

Target ranges for development costs, degree of prescriptive control and range of long term

risks are proposed on the figure. It is evident that for “reasonable” development costs, as

March 2002 23


controlled by the least prescriptive guidelines, a moderate to high risk that the TSF would not

meet the expected standards in the long term would result (horizontal dashed line).

The influence of a high development cost for the same TSF, either imposed through more

prescriptive regulation, or voluntarily spent by the TSF owner, can also be deduced from

Figure 2. The achievement of an acceptable level of long-term risk through high capital

expenditure is, however, presumed to be a less attractive solution to achieving close to the

same level of long-term risk after spending a “reasonable” sum on development.

The figure also illustrates how the long-term risks can be lowered through a process of risk-

based operational management. Assuming that the target development cost is met, it is

possible to comply with non-prescriptive guidelines (as currently prevail in Western

Australia) and still achieve an acceptable long term risk, provided that a process of continual

improvement is adopted throughout the operational phase.

The general concept of continual improvement of an operating system through risk

management is well established (eg AS/NZS 4360:1999 ). The process, as applied to tailings

storage involves the following:

• Determination of risks relating to the operation of a TSF.

• Assessment of the risks through probability evaluation.

• Development of risk response mechanisms to minimise operational risks.

• Implementation and updating of risk management plans.

It is therefore possible to effect a positive improvement in the overall long-term performance

of a TSF from that considered at design stage. This can be achieved through adopting

rigorous operational procedures that ensure compliance with the design assumptions. This

will lead to an upward rotation of the indicator line as shown on Figure 2.

An additional improvement in the long-term risks posed by a TSF can be expected if

performance monitoring procedures are correctly implemented. This is shown by a further

upward trend on the indicator line as shown on Figure 2. Examples of such performance

monitoring procedures are:

• Measurement of piezometric levels in embankments, comparison with expected levels

and implementation of remedial action if levels are higher than predicted.

March 2002 24


• Measurement of borehole groundwater elevations and groundwater quality, comparison

with expected levels and implementation of remedial action if levels are outside the

anticipated range.

• Measurement of underdrain flow rates, comparison of trends with those anticipated and

investigation in the event that flows are significantly lower (or higher) than expected.

• Development of vegetation performance criteria, comparison to expectations and

implementation of alternative plans in the event that objectives are not being met.

• Measurement of tailings consolidation behaviour, prediction of final settlements and

refinement of design to suit the predicted conditions, taking into account uncertainties

through a probabilistic assessment.

Control of operating procedures and performance monitoring, by a process of continuous

improvement, is a form of self regulation. The benefits to the mine operator are enhanced

management of risk and costs. These procedures are most appropriately managed by the mine

operator rather than by regulating bodies. A further benefit is that the operator is able to show

the various stakeholders that acceptable practices and processes for the TSF are in place.

Additional positive rotation of the indicator line as shown on Figure 2 can be achieved

through intervention by external parties, such as shareholders, pressure groups, government

departments, auditors and news media. Although the intervention of such bodies is invariably

seen as negative by mining organisations, the net result in the long-term risk of not meeting

public expectations is usually positive. It is incumbent upon a TSF owner to demonstrate that

long term risks associated with tailings storage are acceptable. If they are not, it is inevitable

that improvements will be required prior to closure of the facility.

Matters for Comment

• To what extent should the Department rely on operational risk management techniquesas opposed to regulatory prescription?

5.3 Waste Minimisation

It is now common for industry to implement the principles of waste minimisation in

management of production activities. This means that managers use the waste hierarchy as a

March 2002 25


guide to assist them in making decisions on waste management or disposal. Wastes should be

managed in accordance with the following order of preference.

1. Avoidance – where possible, processes or materials should be changed to eliminate the

generation of the waste.

2. Reuse – some wastes may be useful as feedstock for other processes.

3. Recycling – the raw materials contained in the waste may be reusable for further

production.

4. Recovery of energy – wastes may be useful as fuel for energy production or substitution.

5. Treatment – it may be possible to make wastes innocuous by further treatment or

processing.

6. Containment – secure storage of wastes in facilities that are isolated from the

environment is often preferable to discharge.

7. Disposal – discharge of waste to the environment under controlled conditions and in a

manner which does not harm the beneficial uses is the final alternative.

In the mining industry, tailings is the major process waste stream. Avoidance or elimination is

not practical in most cases although it may be possible to reduce the volume of tailings wastes

at some mines. In addition some technologies which offer promise for elimination of tailings

wastes, such as in-situ solution mining, introduce other environmental risks. Tailings material

is often reused as stope fill in underground mines and there is scope for further application of

this approach. Where structurally competent fill is required, cement or other stabilising

additives are sometimes added to the tailings material. This is often referred to as paste fill.

An added benefit of paste disposal is that entrained chemicals or trace metals in the ore are

less likely to be leached out and effect ground or surface water.

Some operators now use mechanical drying processes such as belt press filters to remove

most water from tailings prior to storage. This type of process has gained favour in some

extractive industry sites because of it’s potential to reduce waste storage space requirements.

Solar drying of slimes is also practiced at some sites where greater space is available. The

dried clay product resulting from these processes may in some cases be useful as an additive

to brick or ceramic clays.

While drying or stabilisation of tailings can result in lower risks to the environment they also

add cost to the operation and could make some proposed mines uneconomic. The Department

has not to date required the application of any such technology to a mining or extractive

project although some proponents have adopted technologies voluntarily.

March 2002 26


Recovery of energy is not usually feasible from mine tailings although this may be an option

for coal washery reject material. Tailings containing toxic chemicals such as cyanide can

often be treated to neutralise their toxicity. This however, has a significant impact on

processing costs and this must be weighed against the benefits. The majority of tailings

produced at mines in Australia is deposited in carefully designed and constructed storage

facilities where it is intended to be permanently contained.

Matters for Comment

§ Should the Department require proponents to demonstrate the application of the

principles of waste minimisation prior to acceptance of a tailings storage proposal?

§ Is it appropriate for the Department to require an examination of options for drying,

re-use or other innovative waste management approaches before accepting wet storage

proposals.

§ Alternatively, should the Department give general guidance to proponents and rely on

normal commercial and community pressures to ensure best practice in this area?

5.4 Cyanide Management

Sodium cyanide solutions are widely used in the mining industry for recovery of gold and

other non-ferrous metals. They are highly toxic to humans and wildlife and must be very

carefully managed to minimise the associated risks. On the other hand, these cyanide

compounds degrade rapidly in the environment and potential replacement technologies are in

some cases, more risky. From the industry perspective, cyanide is favoured because it is a

proven technology, well understood, easy to manage and available at reasonable cost.

In some operations in other jurisdictions operators have been required to detoxify cyanide

solutions prior to discharge to tailings storage facilities. This has been largely a response to

concerns about toxic effects on fauna (usually birds). In the U.S. state of Montana the use of

cyanide has been banned for similar reasons. It has been demonstrated, however, that such

impacts are usually associated with very high levels of cyanide in the tailings supernatant.

Scientific studies have shown that toxic effects on birds are most unlikely at levels below

50ppm cyanide. This level has been used as a limit for operations in some places while at

others more stringent levels have been imposed. In many cases where strict cyanide levels

have been imposed this has been seen as an appropriate response because of the sensitivity of

the location – eg the existence of a Ramsar wetland nearby or the risk of overflow to a

pristine watercourse.

March 2002 27


Many regulators and some industry groups have advocated operation specific risk assessment

as an appropriate way to determine the need for detoxification or limiting of cyanide levels in

a particular discharge. This would mean that proponents would be required to evaluate the

likely risks associated with disposal of cyanide tailings at a particular location. Risks could

then be eliminated or reduced to appropriate levels by designing controls (such as netting over

dams to exclude birds) or by controlling cyanide levels. The approach could be codified in the

guidelines or assessments could be carried out on a case by case basis

Matters for Comment

§ Should the Department require detoxification of cyanide in tailings. If so should this be

a blanket ban or a requirement for particular circumstances?

§ Alternatively should we require a detailed risk assessment for management of cyanide

tailings prior to completion of design so that the management approach can take into

account the risks ?

5.5 Site Selection

Selection of the site for a tailings dam often requires analysis of a number of competing

factors. The chosen site may have a significant effect on overall cost because of differing wall

or lining requirements. Site selection may also be influenced by the flora or fauna impacts

associated with loss of a particular area of land. Valley sites offer simplified construction and

reduced cost as wall lengths are usually shorter. They also offer the advantage that any escape

or seepage of tailings or supernatant can be expected to occur along the drainage line and

backup structures or systems can be emplaced there for greater security. The disadvantage of

this type of structure is that it is located in what was once a water course. Natural runoff must

therefore, be diverted around the structure. This can result in risks to the tailings storage

facility such as erosion by adjacent flows or overflow as a result of failure of the diversion

system.

Hillside or ring dyke storage designs can reduce the risks associated with water course

diversion but do not have some of the inherent advantages of the valley design. Site rainfall

and hydrology should be considered also in assessing the merits of competing locations. For

example diversion of a watercourse may represent negligible risk if rainfalls are low but be a

difficult engineering problem in a high rainfall area.

Matters for Comment

§ Should the Department prescribe the circumstances in which valley dams can be

constructed?

March 2002 28


§ Should the guidelines set out criteria for selection of the TSF site?

§ Should certain types of location be excluded for certain types of tailings?

5.6 Community Participation

Participation by the communities effected by a proposed facility and other stakeholders is

widely believed to be a valuable element of the design process. In the case of a TSF, the siting

and fundamental design criteria of the facility might give rise to concern among neighbours or

local groups for a variety of reasons. The risks of pollution, inundation or impacts on flora or

fauna may all be valid reasons for concern. It is likely that any project of significant scale will

include consultation activities in any case, through Statutory Planning or Environmental

Assessment processes. Respondents to this discussion paper are therefore asked to consider

whether the usual processes are adequate to address concerns with the establishment of

TSF’s.

Matters for Comment

• Should the Department prescribe or recommend additional processes of community

consultation in respect to TSF design and siting

• Alternatively, is the usual wider consultation process adequate provided sufficient

information and opportunity for input is available.

5.7 TSF Design

A number of factors are considered in the design of a tailings storage facility. The following

sections outline those thought to be most important. However, respondents should feel free to

comment on any aspect of design they consider significant.

5.7.1 Wall Type

Construction of conventional dam style TSF’s usually involves an initial wall with subsequent

lifts added as the need arises. Three main types of wall construction are in common use (refer

to section 8.3.1).

Upstream lift construction is a widely used technique which is very cost effective. It has been

the most common technique used in recent years in Victoria. The method is less inherently

March 2002 29


safe than other methods and has been disallowed in some jurisdictions where seismic activity

is a serious concern. However, facilities constructed in Victoria using this method have

performed well and there have been no recorded problems associated with the technique in

this State.

Downstream construction is the most inherently safe but also the most expensive method of

construction. It is required in some jurisdictions where seismic loadings are a significant risk.

This technique has not been used to any significant extent in Victoria. Associated

disadvantages are that the TSF footprint expands during operation and the large quantities of

construction material needed give rise to larger incidental impacts.

Centre line construction is a compromise between the downstream and upstream methods. It

offers greater stability than upstream construction but is not as costly as downstream

construction.

Matters for Comment

§ In what circumstances (if at all) should the Department prescribe the type of lift

permitted on a TSF?

§ Should the use of upstream lifts be limited to some circumstances? If so what would be

the determining factors for disallowing such a design?

§ Should proponents be required to define the type of lifts proposed at the time of initial

approval?

Most TSF’s constructed in recent years in Victoria have been designed to a standard adequate

for the storage of water. It is sometimes argued that this is unnecessary as deposited tailings

usually increase the stability of the structure and are often relatively impervious once settled.

The extent to which this is true depends on the chemical and physical characteristics of the

tailings that are produced. In metallic mines where the tailings are often fine grained, the

resulting tailings mass can become quite low in porosity. In arid areas in other states this

characteristic has been exploited to the extent that dried tailings material is used at some sites

to construct TSF walls. This is usually done by the “ contruction by operation” method where

the wall is continually lifted using cycloned tailings sand as tailings deposition is in progress.

Matters for Comment

• Is construction of TSF’s to water containment standard necessary or could otherstandards be acceptable in some circumstances

March 2002 30


5.7.2 Water Recovery

Tailings storage structures must accommodate rainfall on the storage catchment as well as the

volume of tailings deposited. TSF’s in Victoria have been designed to date with no allowance

for discharge of water. It is assumed that designs have been correctly developed to

accommodate the largest likely rainfall events and discharge will never be required. In some

other jurisdictions all tailings storages are required to include discharge spillways. This is

based on the concern that design information may be imperfect or an unprecedented rainfall

event might compromise the capacity of the facility. In this situation it is argued that it is

better to have a controlled discharge via an engineered spillway than a situation where the

dam overtops in an uncontrolled way. The latter situation is unlikely but could have very

serious consequences if it did occur including possible structural failure of the storage facility.

Many TSF’s are used as water storage dams as well as for tailings storage. Water and

contained process chemicals are recovered from the dam and re-used in the treatment plant.

Most dams in Victoria to date have been managed in this way. Water can be removed using a

variety of designs including floating or submerged pumps, constructed decant towers or

syphons. Minimisation of the amount of water held by the TSF is often important where sub-

aerial deposition is used to ensure consolidation of the tailings mass. In some cases a separate

water recovery dam (or decant dam) is included so that water can be continually drained from

the TSF. This may further aid the drying and consolidation of the deposited tailings in many

cases. In addition some dams have been constructed with pre-installed drainage piping under

the tailings. This feature has been successful in some cases in improving the consolidation of

tailings but is expensive and can fail quickly if the consolidated tailings material is low in

permeability.

Important Note – TSF’s designed to contain potentially acid forming tailings materials are

often designed to have a permanent water cover (ie sub-aqueous deposition). In such cases the

above discussion clearly does not apply. Management of such storage facilities introduces a

range of additional issues. To ensure permanent cover, water recovery, losses and rainfall

catchment must be carefully balanced. This is most critical after rehabilitation when the

facility must be safe with a minimum of management intervention. The issues involved are

discussed further in the decommissioning section of this chapter.

Matters for Comment

§ Should the Department prescribe water recovery methods for TSF’s?

March 2002 31


§ Should we require the inclusion of decant facility where sub-aerial deposition is

proposed?

§ Should under-drainage be required in some cases and if so, in what circumstances?

§ Should the Department require inclusion of a designed emergency spillway in TSF’s

even though designs are based on a no discharge premise.

5.7.3 Permeability of the enclosure

TSF’s constructed in Victoria have for some years been required to include a liner with

permeability no greater than 10-6cm/sec for a thickness no less than 30cm. This is usually

achieved by compaction of in-situ clays but in some cases artificial liners have been used.

Some seepage of contained water into the substrate is desirable as it improves the drying and

consolidation of the tailings material. However, this must be balanced against the need to

protect groundwater resources and nearby surface watercourses from contamination. Most

TSF’s constructed to date in Victoria have been on relatively low permeability substrates and

remote from usable groundwater but this may not always be the case.

More stringent permeability standards apply for similar controlled attenuation liners in sites

such as municipal landfills. It has been argued in some cases that the same requirements

should apply to TSF’s. The counter argument holds that tailings deposition generally reduces

the permeability of a TSF as it is filled, that the contaminants contained in tailings are often

quickly attenuated during transport through soils and clays and that the location of most

tailings dams pose no threat to useable groundwater.

Matters for Comment

§ Should the permeability requirement for TSF’s be retained, amended or,

§ Should a case by case risk assessment approach be adopted to ensure the permeability

standard applied suits the circumstances.

5.7.4 Design Approval

At present operators are required to describe proposals for TSF construction in their Work

Plan which is approved under the Mineral Resources Development Act 1991 or the Extractive

Industry Development Act 1995. The Department considers that a more rigorous process is

required to ensure that TSF designs are adequate for the proposed use, up to contemporary

March 2002 32


standards and have considered all the likely hazards associated with the materials, site,

storage process, and closure of the facility.

Most jurisdictions require engineering designs for large TSF’s. However, the degree to which

Government checks and approves designs varies considerably. In WA for example the

regulator accepts proponent assurance that design has been conducted to an adequate standard

provided the individual making the submission has an appropriate professional affiliation.

Some years ago in Victoria a system existed where designs were reviewed by an

interdepartmental committee including the Environment Protection Authority (“EPA”), the

former Rural Water Commission (“RWC”) and other authorities. This system was abandoned

when the responsibilities of the RWC were devolved to a number of other corporate entities.

Such a system could be re-established but since that time the level of dam design expertise

within Government is thought to have diminished. It is therefore appropriate to consider

whether other approaches can be adopted to ensure the right level of expertise is applied to

developing and checking designs. This could be done by defining qualifications for TSF

design engineers, requiring accreditation of designers or by requiring a third party review.

Matters for Comment

§ Is Department approval of designs necessary, or

§ could we rely on the application of good design based on principles set out in

guidelines?

§ Should the Department:

§ Accept proponent self certification of designs, or

§ Require design by a professional engineer meeting certain requirements, or

§ Accredit engineers considered qualified to design TSF’s.

§ Should a third party review of designs be required prior to Department acceptance or

implementation

§ Should other agencies such as EPA, water authorities or Catchment Management

Authorities be involved in assessment of designs and if so in what way?

5.8 Construction

It is essential that construction of a TSF is undertaken in accordance with the design and to a

high standard of workmanship. Critical factors are that walls are correctly keyed in, materials

are chosen correctly and emplaced to the correct compaction levels, that ground conditions

have been properly monitored and that appropriate remedial works have been undertaken

where zones of higher permeability or lower structural strength are encountered in the

March 2002 33


substrate. Some designs rely on more technically complex features such as grout curtains or

geo-membrane liners. In these cases it is important that work is supervised by professionals

with specific expertise and that the materials used are compatible with the rest of the design.

A range of regulatory systems can be applied to ensure good quality assurance during

construction. The options are broadly similar to those outlined in the above section on design.

Many jurisdictions require a written report on completion of construction. Some rely on

written verification by a mine manager or other company officer that the facility was built to

design. In other cases expert or third party reports are required.

Good supervision by suitably qualified professionals during construction can reduce the need

for tests or assessment at completion. In fact it can be argued that some involvement in the

construction is essential in order for an assessor to be able to verify compliance with the

design.

Matters for Comment

§ Should the Department require a detailed “as constructed” report?

§ Should the Department:

§ Accept proponent self verification of construction to design, or

§ Require assessment by a professional engineer meeting certain requirements, or

§ Accredit engineers considered qualified to report on construction of TSF’s?

§ Is it necessary to prescribe requirements for the supervision of construction work on

TSF’s?

5.9 Operation

The operational phase is for most TSF’s, the longest part of the facility life cycle. It involves

the systematic deposition of tailings in the facility along with water and process chemicals.

Although these processes are simple, minor variations in the way they are carried out can

have significant impacts on the outcomes. In some possible designs for example, it is assumed

that structures like dam walls will be quickly reinforced with deposited tailings. Clearly this

may not be the case if discharge spigots are not correctly located early in the use of the

facility and the risk of structural failure may be raised as result. More commonly, the

deposition arrangements do not adequately consider the needs of rehabilitation. Well planned

operational practices can reduce long term costs and minimise risks to the environment. A

number of significant operational factors are discussed in the following sections.

March 2002 34


5.9.1 Water Management and Tailings Deposition

Good water management is critical to the safety of the facility and the quality of the final

outcome. Water levels in TSF’s must be kept to safe levels within the design capacity of the

structures and appropriate freeboard must be maintained at all times.

At facilities where a dry tailings mass is the final goal and sub-aerial deposition is used, it is

important that tailings are discharged to a beach of tailings material. This maximises the

evaporation of water and assists in degradation of cyanide compounds where they have been

used in the treatment process.

Tailings are often deposited in a TSF by discharge at points around the perimeter. This assists

in sealing the base of the impoundment and can improve the stability of constructed elements

such as dam walls by rapidly adding a beach of coarse fraction material. The disadvantage of

this approach is that the fine fraction tends to be deposited in the centre of the storage. This

can create a concave land form and if not managed carefully can result in an aggregation of

slimes material in the centre of the storage which is very difficult to manage during

rehabilitation. An alternative method involves discharge at the centre of the dam at some or

all stages of filling. A logical progression of this approach is the so called central thickened

discharge (or “CTD”) method where tailings material is de-watered to a certain extent prior to

discharge. CTD has the added benefit that it allows construction of a convex landform which

is more amenable to rehabilitation.

In some cases tailings have been deposited as a mixture with waste rock. This is usually

referred to as co-disposal. The advantages of this approach include rapid stabilisation of the

tailings mass which allows earlier access for rehabilitation and greater safety in applications

where fluidisation of the tailings under mechanical or seismic stimulus could pose a risk. The

method has been proposed for use in cases where tailings storage was proposed in an active

mine pit and where tailings were particularly hard to dry prior to rehabilitation. Disadvantages

include a need for greater storage volumes and more complex (and costly) tailings handling

arrangements. Although the technique is not suitable in all cases, it’s wider use could reduce

the need for storage of tailings in large dams and significantly reduce environmental risks in

some cases.

Matters for Comment

§ Should the Department guidelines prescribe acceptable methods of tailings discharge

or deposition?

March 2002 35


§ Should CTD or similar approaches be encouraged?

§ Should co-disposal be more widely considered?

§ Are wet storage facilities acceptable in all cases?

§ If not acceptable in some cases, what factors should be considered?

5.9.2 Environmental Monitoring/Transfer Reporting

A carefully designed program of environmental monitoring is considered an essential element

of good management for modern tailings storage facilities. Most operators have well

developed programs measuring significant environmental parameters. The most commonly

monitored environmental aspect is groundwater and it is usual for a number of bores to be

installed at selected locations around a TSF to enable monitoring of both the level and quality

of groundwater. A good understanding of the local groundwater environment and chemistry is

necessary in order that bores are located in appropriate places and drilled to the correct depth.

In some cases multiple bores are required to intercept different acquifers and it is also

common to install shallow bores near dam walls to permit detection of any seepage that might

occur. Where surface watercourses occur near a TSF it is also good practice to monitor

upstream and downstream from the facility. Although in most cases no discharge is permitted,

monitoring allows the operator to verify compliance and ensure that no contamination has

occurred by any other pathway.

A range of other parameters can be monitored. In situations where aerial sprays are used to

enhance evaporation, it has been considered necessary to monitor spray drift and to visually

monitor effects on the vigour of adjacent trees. At some sites it may be necessary to monitor

the stability of dam walls and other earth structures. An area of particular interest to some

observers is the monitoring of volumes and chemical characteristics of tailings and process

water transferred to or from TSF’s. Tailings transfer parameters have not been reported to

Government in the past although in many cases operators have probably gathered the data for

their own use. These parameters are considered important as they can provide an

understanding of the characteristics of the waste stored in the TSF which may be important

for future land management decisions. The information could also provide insight into the

degree to which an operator has successfully applied waste minimisation principles to their

operation.

Monitoring of effects on fauna may also be regarded as an important requirement. (Birds in

particular are susceptible to death as a result of poisoning by drinking tailings supernatant.

March 2002 36


The most well publicised example of this problem occurred at Parkes in New South Wales in

1995 where a large flock of birds died in this way. There have been no known similar events

in Victoria although individual bird and animal deaths have been reported.) More systematic

reporting of fauna effects might improve our understanding of whether there is a serious risk

of such effects.

Matters for Comment

§ What environmental parameters do you consider require monitoring at a TSF?

§ Should the Department specify some parameters for monitoring at all TSF’s or

§ Rely on a site by site risk assessment to define the critical aspects?

§ Should the Department require monitoring and reporting of tailings transfers?

5.9.3 Maintenance /Pipelines and Tailings Handling Equipment

Tailings management at most mine sites incorporates activities such as conveyance of tailings

by pipeline, pumping of tailings and decant water, discharge spigotting and in some cases

separation or drying processes. All of these activities introduce a risk of accidental discharge

as a result of failure of mechanical systems or materials. Many small environmental incidents

that have occurred in the past in this and other jurisdictions have been the result of broken

pipelines, faulty control devices or other similar failures. Appropriate maintenance and

replacement schedules for mechanical equipment are necessary for safe operation. It is also

true that in many cases passive installations such as dam walls or drains also require regular

maintenance – for example where high rainfall results in regular erosion of constructed

features.

Most tailings pipelines at Victorian mines are required to have control systems designed to

shutdown the supply pump if a no-flow condition is detected at the discharge end of the

pipeline. This ensures that the tailings supply is stopped if a catastrophic failure occurs in the

pipeline. These systems do not, however, eliminate the risk of a discharge event where a

pipeline develops a serious leak but does not fail completely. Most existing pipelines are also

constructed in trenches or between parallel bunds so that spillage is directed to dedicated

catch dams. Unfortunately some escapes have still occurred where liquid under pressure has

escaped as a jet at an elevated trajectory. Some operations in other jurisdictions have adopted

novel mechanisms to minimise the chance of such events such as completely encasing the

pipeline in a secondary sleeve or constructing covers over pipe joints.

March 2002 37


Matters for Comment

§ Should the Department require documented maintenance schedules as part of the

operating documentation for a TSF? or

§ Should we specify inspection and maintenance criteria for critical elements of the

facility?

§ Is it necessary to adopt measures for increased safety on tailings pipelines such as

secondary sleeves or would increased attention to maintenance issues be a better

solution?

5.9.4 Emergency Preparedness/Incident Reporting

Most TSF’s constructed in Australia in recent years have been well designed, soundly

constructed and competently operated. As a result serious accidents and incidents associated

with TSF’s have been rare in this country. However, the consequences of a major failure at a

large TSF could be very serious. Accidents in other parts of the world have demonstrated that

such events can lead to very major contamination of waterways, major impacts on flora and

fauna and sometimes the loss of human lives. It is important therefore to be prepared for the

worst case. A well developed emergency response plan (“ERM”) should include procedures

describing and prioritising actions such as notification of emergency services, advice to

neighbours, protection of personnel and immediate and longer term remedial actions.

Implementation of such a plan could make a significant difference to the outcome of an

accident at a TSF.

In addition to development of an ERM, the safety of tailings storage operations can be

enhanced by processes for the sharing of experience and knowledge regarding accidents and

incidents. Incident notification systems already function in Victoria and other jurisdictions for

the dissemination of information on workplace accidents. These systems include mandatory

notification of incidents and accidents by licensees to the Department. The Department then

circulates incident reports to licensees and other jurisdictions for information. Similar systems

could be introduced for tailings management systems and might improve industry awareness

of common risks.

Matters for Comment

• Should the Department require a dedicated Emergency Response Plan as part of the

documentation for approval of a TSF or is it adequate for this aspect to be addressed as

part of the overall mine plan?

March 2002 38


• If an ERM is required should this requirement be applied to all TSF’s or only those

where size or location indicate a high risk?

• Should tailings management incidents and accidents be reported in a similar way to

safety incidents?

5.10 Decommissioning

It is important to recognise that most TSF’s must store tailings material securely for an

indefinite period. The enclosure and the rehabilitation works applied to it must therefore be as

inherently stable and resistant to degradation as possible. This must usually be achieved with

minimal maintenance or upkeep.

The closure of a TSF can involve a number of processes. In some cases significant

engineering works may be involved such as the construction of a spillway and alteration of

surface drainage controls to establish a permanent water cover or the construction of a layered

dry cover. In many cases stored tailings must first be dried over a long period to establish

conditions suitable for earthworks with heavy equipment. However, where tailings do not

contain toxic materials, revegetation can sometimes be achieved with very little remediation

of tailings materials and only minor earthworks.

5.10.1 Planning for Closure

Early planning for closure of a TSF can reduce risks for both the community and operator and

minimise costs at the end of project life. An area of significant concern to the Department in

the past has been the fact that most TSF’s require large quantities of cover material for

closure. In many cases the source of this material was not considered at an early stage and

there was a serious shortfall of fill when the works were required. As a result, since the early

1990’s the Department has required that proponents demonstrate the source of cover material

in their initial plans. Many other practical problems can be avoided by careful planning at

design stage. As discussed in the “Operation” section the type of deposition used and the

design for water recovery can also have significant influences on the costs and risks

associated with closure.

5.10.2 Cover Design & Revegetation

The appropriate cover design is usually determined by the nature of the tailings in a TSF.

Designs vary from quite complex multilayer earth and rock covers to those where only a

March 2002 39


surface growing medium is necessary. In cases where the material is sulphitic it may for

example, be essential to exclude oxygen from the substrate and the cover must therefore

include an anoxic layer or impermeable barrier. In such cases, water covers or designs

incorporating an artificially high water table are often used. In cases where the tailings are

less reactive, impermeable layers may not be required but it may be necessary to install a

layer of broken rock to stop capillary rise or to use a high volume of material in order to have

sufficient depth of soil for root establishment. Because of the diversity in materials and

objectives it is considered impractical to prescribe designs for TSF covers. The Department

considers the best approach to this element of design is a case by case analysis of the

objectives and risks. However, it could be argued that a minimum set of criteria for cover

depth and design elements should be applied.

The type of cover chosen is influenced also by the desired re-vegetation outcomes. In some

cases large depths of soil and rock cover have been used to ensure adequate cover for tree

growth while in others where the area was expected to return to pasture, the cover depth

requirement has been much less stringent. It is of concern that some cover designs where the

revegetation has involved planting of trees may be compromised in future by breaching of the

cover when trees fall or are removed. The potential for erosion of enclosures in future is also

of concern and this risk is increased where the area is used for commercial forestry or

farming.

Matters for Comment

• Should the Department prescribe minimum design criteria for TSF covers or is it

preferable to assess designs on their merits.

• Should the types of vegetation or future activities permitted on closed TSF’s be more

limited.

5.10.3 Maintenance/ Long Term Management

Tailings storages are long term or permanent facilities and must be designed with this in

mind. However, even the best designed facilities will in time require maintenance or care.

Many such facilities are constructed on Crown land and will therefore be the responsibility of

the community in the long term. In cases where they are built on private land, any future

problems might in any case become a community concern if they are serious enough to be

beyond the resources of a landowner. At present there are no arrangements in place to ensure

the long term maintenance or monitoring needs of TSF’s are addressed. Although recent

amendments to the Mineral Resources Development Act 1990 make compensation payable to

the Crown for losses associated with the use of land, they do not provide for future costs. It

March 2002 40


may be appropriate for the Department to negotiate closure agreements with proponents that

incorporate financial arrangements for such contingencies. Alternatively further analysis

might indicate that the present benefits outweigh future likely costs .

Matters for Comment

Should the department introduce policies for the recovery of future costs associated with

care and maintenance of TSF’s.

March 2002 41


DISCUSSION PAPER:

TAILINGS STORAGE


Part 2

Background and Literature Review

March 2002 42


6 VICTORIAN GEOGRAPHY, CLIMATE AND MINING ACTIVITIES

6.1 Physiography

Victoria has an area of approximately 227,600 km2, representing just less than 3% of the total

surface area of Australia. The boundaries of the State cut across two distinctly different

physiographic regions:

• the flatter Murray Lowlands (containing the Mallee Dunefield and the Riverine and

Wimmera Plains) of the north and west of the State, and

• the more mountainous Eastern Uplands (containing the Alps; the East Victorian, West

Victorian and South Victorian Uplands; and the West Victorian and Gippsland Plains) of

the south and east of the State.

The Uplands are mainly associated with the slopes of the Great Dividing Range running from

the northeast to the southeast of the State, with consequent stream flows off the slopes and

towards the coast in the south and towards the Murray River in the north. The exception is

the South Victorian Uplands associated with the Otway and the Strzelecki Ranges. Streams

flow towards the coast or meet with stream flows from the Eastern Uplands and flow to the

Gippsland Lakes or to the sea near Barwon Heads.

6.2 Climate

Victoria’s climate is often termed Mediterranean, with warm dry summers and cool wet

winters. The climate is influenced by the coast (with all areas within the State being within

380 km of the coast) and by Australia’s arid centre, which produces dry northwesterly air

streams and high temperatures in summer.

Highest rainfalls are generally associated with higher elevations and exposure to the moist air

streams moving from west to east across the southern portion of the State. Consequently,

rainfall is lowest in the northwest of the State and highest in the Alps, the Otway and the

Strzelecki Ranges. Frosts are rare in coastal regions but can be frequent and severe in inland

areas. Snow is mostly encountered only in the Alps in winter and early spring.

Thunderstorms typically occur during summer when moist air from the tropics or the sea

intrudes over Victoria.

March 2002 43


6.3 Mining

Historically, Victoria owes much of its wealth and development to the gold discoveries of the

nineteenth century. Gold continues to be mined from numerous sites across Victoria.

Victoria’s mineral wealth is, however, not confined to gold. Aluminium, Antimony, Barium,

Chromium, Cobalt, Copper, Diamond, Diatomite, Feldspars, Fluorite, Gypsum, Iron,

Kaolinite, Lead, Limestone, Manganese, Molybdenum, Phosphate, Pyrite, Silver, Talc,

Thorium, Tin and Uranium are all found in Victoria. Only Tin and Antimony have been of

more than minor importance to date. Enhanced exploration and extraction methods and

technology offer the possibility that known deposits may become economically viable.

Current (1999/2000) annual investment in mineral exploration is of the order of $35 million

(from $12 million in 1992/93), while annual mineral (non coal) production in Victoria is

valued at approximately $100 million.

Extensive brown coal deposits are mined in the Latrobe Valley and oil and gas fields are

exploited in the Gippsland and Otway Basins. TSF are not relevant to oil and gas production.

Coal extraction is governed by the Mineral Resources Development Act 1990 (“the Act”) and

produces a tailings-like waste stream in the form of ash from coal burning for power

generation. The generating stations and the associated waste storage facilities are not,

however, controlled by the Act. Ash disposal is subject to licence under the Environment

Protection Act 1970.

6.4 Extractive Industries

Quarrying of construction materials – sand, gravel, stone for building and for crushed

aggregates, limestone for cement and lime and clays for brick and tile making – is a major

industry across Victoria. In the year 1999/2000 sales of quarry products werer valued at

approximately $330 million.

March 2002 44


7 VICTORIAN LEGISLATION AND POLICY

7.1 Government Policy Framework

Energy and Minerals Victoria (EMV) is a business unit of NRE. EMV’s role includes

undertaking the promotion, facilitation and regulation of the extractive, minerals and

petroleum industries in Victoria (including offshore waters on behalf of the Commonwealth).

Victoria's strategic priorities provide a framework for the operation of NRE, especially EMV

and specifically include:

• Generating wealth through sustainable development of industry and natural resources.

• Protecting natural resources and the environment for the long-term benefit of allVictorians.

• Improving the quality of life of all Victorians, and

• Improving land and resource information.

All aspects of mining and extractive industry operations must conform to relevant State

legislation, regulations and policy.

7.2 Mining Legislation

The Mineral Resources Development Act, 1990 establishes a two stage process for the

approval of mining work:

• the granting of a licence; and

• the approval of a Work Plan and the granting of a Work Authority.

Prior to issuing an Authority, the Chief Administrator must be satisfied that the applicant has

an approved Work Plan.

Schedule 14 of the Mineral Resources (Titles) Regulations, 1991 prescribes the requirements

of a Work Plan, depending for example on the size of the operation, site location, design plans

and sections, proposed stormwater and water management, tailings management, proposed

rehabilitation plan and environmental monitoring program.

March 2002 45


7.3 Extractive Industry Legislation

The Extractive Industries Development Act, 1995 controls the assessment and approvals

process for extractive industries; ensures that extractive industry operations are carried out

with safe operating standards and in a manner that ensures the rehabilitation of quarried land

to a safe and stable landform; provides a procedure for notification of proposed extractive

industries to licence holders under the Mineral Resources Development Act, 1990; and

provides for payment of royalties for stone extracted from Crown Land. The Act establishes

the following staged process:

• Preparation of a Work Plan / proposals .

• Planning Permit application to Municipal Councils.

• Council determination after referral to Referral Authorities (including EMV).

• Approval of the Work Plan.

• Granting of Work Authority and any conditions.

7.4 Environment Protection Act, Regulations, Policy & Guidelines

The principal legislative vehicle for environmental protection control in Victoria is the

Environment Protection Act, 1970, which aims to prevent or reduce pollution in three ways:

• Encouraging waste avoidance, reduction and re-use.

• Controlling the emissions of waste into the atmosphere and on land and water.

• Imposing sanctions against those who have polluted.

A workable definition of “pollution” is fundamental to the operation of the Act. The essential

element of the concept of pollution is that it is something which causes a detrimental change

in the condition of the environment. Whether an emission or discharge of “waste” amounts to

pollution depends upon the consequential change to the environment or whether the

“beneficial use(s)” of that segment of the environment has been adversely effected.

March 2002 46


“Beneficial Use” is described as a use of the environment or any element or segment of the

environment which is conducive to public benefit, welfare, safety, health or aesthetic

enjoyment and which requires protection from the effects of waste discharges, emissions or

deposits, or the emission of noise.

The Act regulates the discharge or emission of waste to water, land or air by a system of

Works Approvals and Licences. The Act also specifically controls the emission of noise, the

disposal of rubbish and the transportation of waste.

Acceptable environmental quality standards and conditions for discharging waste and

identification of uses of the environment are specified in the relevant State Environment

Protection Policies (SEPPs). These set out Government policies to control and reduce

environmental pollution and have been formulated for discharges to atmosphere, water, and

land and noise emissions.

SEPP (Waters of Victoria) determines the beneficial uses of the water environment to be

protected, water quality indicators and objectives for specific segments of the water

environment.

SEPP (Groundwaters of Victoria) aims to maintain and, where necessary, improve

groundwater quality sufficient to protect existing and potential beneficial uses.

Section 16(1A) of the Environment Protection Act 1970 requires that the management of

industrial waste must be in accordance with the provisions contained within declared Industrial

Waste Management Policies (IWMPs). The key IWMP is the IWMP (Waste Minimisation)

which establishes a framework which promotes the adoption of industry practices, processes

and technologies which will minimise the generation of industrial waste.

Premises requiring Works Approval and Licensing under the Environment Protection Act

1970 are described as scheduled premises and are listed in the Environment Protection

(Scheduled Premises and Exemptions) Regulations 1996. Under these regulations, premises

with solely land discharges or deposits, used for the discharge or deposit of mining wastes, in

accordance with the Extractive Industries Development Act 1995 or the Mineral Resources

Development Act 1990 are exempt from Works Approval and Licensing requirements.

Other relevant regulations/policy pertaining to the management of waste includes:

March 2002 47


• EPA Industrial Waste Strategy - Zeroing in on Waste (1998).

• EPA Information Bulletin "Guidelines for Preparation of Waste Management Plans”

(Publication No. 383, August 1993).

• Environment Protection (Prescribed Waste) Regulations (1998).

• EPA Technical Guideline "Bunding Guidelines" (Publication No. TG 201, December

1993).

• EPA Information Bulletin “Classification of Wastes” (Publication No 448, May 1995).

7.5 Other Environmental Legislation

The Environment Effects Act (1978) provides for the Minister for Planning to decide whether

an Environment Effects Statement (EES) is required for any proposed development. Where

an EES is required approval procedures are coordinated as closely as possible. A proponent

undertaking an EES is not required to obtain further planning approvals for the activities

assessed in the EES.

The Planning and Environment Act (1987) provides a framework for planning the use,

development and protection of land in Victoria. The Act has a number of aims related to

environmental protection, social equity and facilitation of appropriate development.

The Act provides the overarching process for the consideration and approval or disapproval of

mining and extractive industry applications by Responsible Authorities (RA). In most

instances the RA is the relevant Municipal Council, utilising the approved Planning Scheme,

including the State Planning Policy Framework which addresses mining and extractive

industries. The RA is required to refer all applications to the Referral Authorities. In the case

of mining and extractive industries, EMV is a Referral Authority.

There is provision for appeal to the Victorian & Civil Administrative Tribunal.

The Flora and Fauna Guarantee Act (1988) establishes a legal and administrative structure to

enable and promote the conservation of Victoria’s native flora and fauna and to provide for

choice of procedures which can be used for the conservation, management or control of flora

March 2002 48


and fauna and the management of potentially threatening processes. The objectives of the Act

include:

• Taxa survive, flourish and retain their potential for evolutionary development in the wild.

• The conservation of communities of flora and fauna.

• The management of potentially threatening processes.

• That any use of flora and fauna by humans is sustainable.

• Genetic diversity of flora and fauna is maintained.

Threatened species and communities are listed in schedules to the Act.

The Catchment and Land Protection Act 1994 aims to:

• Establish a framework for integrated management and protection of catchments.

• Encourage community participation in the management of land and water resources.

• Set up a system of controls on noxious weeds and pest animals.

Of the ten Catchment and Land Protection Boards established in the Act, nine Boards have

evolved into Catchment Management Authorities as a result of amendments to the Act in

1997.

7.6 NRE Information Sheets

NRE Mining Licences Information Sheet (July 1998) provides a guide to the Department’s

approach to the approvals process and assessment factors and criteria.

NRE Guidelines for Environmental Management in Exploration and Mining – Rehabilitation

Plans (& Other Environmental Aspects of Work Plans) Information Sheet (July 1998)

provides a guide as to the Department’s approach to rehabilitation, and briefly to the

rehabilitation of TSF, including cover, water management, access, erosion control,

revegetation and best practice.

The Information Sheet ‘NRE Guidelines to the Extractive Industries Development Act (May

1998)’ provides a summary of the legislative and regulatory changes that resulted from the

assent of the above Acts and Regulations. The guideline provides a simplified approvals

flowchart.

The Information Sheet ‘NRE Guidelines about Work Plan Information for Extractive

Industries over an area of 5 ha or more, or greater than 2 metres in depth (May 1998)’

March 2002 49


describes the information required to be contained in a Work Plan for a Work Authority

covering an extractive industry as per the Act. It includes location, site plan, geology,

description of proposed quarry, environmental management program, rehabilitation,

consultation etc.

‘NRE Guidelines for Extractive Industries’ provides advice about issues associated with the

extraction of stone under the Extractive Industries Development Act, 1995 and the Extractive

Industries Development Regulations, 1996. This includes: What is an extractive industry?

When is approval required? What are the various stages of the approval process? What do

certain terms mean?

7.7 NRE Requirements for the Work Plan

To satisfy the Chief Administrator the following information is commonly presented in the

Work Plan:

• A location plan showing topographic features at the site, the general location of the TSF

and access roads to the site.

• A plan of the TSF site showing details of the working area, the topography and site

drainage.

• If the final height of the TSF embankment exceeds 5 m and its the final capacity is greater

than 50 Ml, then an engineering design of the embankment must be submitted showing a

section through the long axis of the embankment, cross sections, details of catch drains to

intersect seepage and details of blanket drains.

• If the final height is less than 5 m and the capacity is less than 50 Ml then the applicant

must stipulate the design parameters used (may be from approved small dam design

manuals).

• The geology of the area to be covered by the TSF and assessment of its ability to support

the loads of the TSF.

• Depth to groundwater.

• Seepage analyses for the TSF.

March 2002 50


• Identification of sources of construction materials for the embankment and liners and data

on their engineering properties (including dispersion tests).

• Catchment information and analysis and determination of “worst case” storm events

(typically highest recorded storm event or 1:100 year recurrence storm determined for 1,

3, 7 or 15 day periods).

• Location and design of diversion drains.

• The scheme and management of tailings deposition into the TSF.

• Location, design and operation of decant facilities.

• The location and design of delivery and return pipelines including pipe break contingency

plans to avoid contamination of watercourses.

• Details of the chemistry of the tailings (including reagents).

• Erosion control measures to be adopted on the TSF.

• Stability computations for the embankment, both for static and for the “expected” (OBE)

seismic event.

• The design must satisfy the “worst case” combination of factors (eg. full TSF, wave

action, design storm).

• Details of monitoring boreholes including the location and depth of boreholes and the

proposed monitoring program.

March 2002 51


8 INTERNATIONAL MINING GUIDELINES, CODES AND STANDARDS

8.1 North America

8.1.1 Canada

“A Guide to the Management of Tailings Facilities” (Mining Association of Canada, 1998),

presents a full life cycle TSF management framework, from planning and design, through

construction and operation, to eventual decommissioning and closure. The framework is

expanded into a series of checklists, each of which addresses various stages of the life cycle.

Appended to the document are lists of technical considerations that cover the environmental

setting, design, and operating aspects that are typically encountered throughout the TSF life

cycle.

A TSF management framework is presented. It consists of five linked and continuous

elements:

• Policy and Commitment.

• Planning.

• Implementing the Plan.

• Checking and Corrective Action.

• Management Review for Continual Improvement.

Four stages are identified in the life cycle of a TSF:

• Site Selection and Design.

• Construction.

• Operation and Decommissioning.

• Closure.

The management framework is applied to each of the life cycle stages in turn, with reference

also to the technical considerations.

March 2002 52


The approach recognises that responsibility for TSF management may rest with different

groups within a company and that the emphasis changes during the different stages of the life

cycle. The checklist approach assists in identifying the stages and roles and provides a

management framework. The system requires that actions be planned within the context of

agreed policies and commitments, implemented in accordance with the plans, checked and

corrected and subjected to management review. Each checklist has six columns, each of

which addresses a key element in implementing the management framework. These elements

are:

• Management Action.

• Responsibility.

• Performance Measures.

• Schedules.

• Technical Considerations.

• References.

These elements can be customised to address a mining company’s tailings management and

operating needs.

It is intended that mine management use the checklists to:

• Develop operating procedures and manuals.

• Identify gaps within existing procedures.

• Communicate with stakeholders.

• Assist in obtaining permits.

• Assist in achieving compliance and due diligence.

The approach is designed for self-management and allows a mine management to

demonstrate due diligence, complement government regulations and protect the environment

and the public.

March 2002 53


8.1.2 USA

Regulation of mining in the USA is the responsibility of individual states. Jurisdictional

processes vary from state to state with a focus on outcomes rather than operating procedures.

For example, the Bureau of Mining Regulation and Reclamation (in cooperation with other

state, federal and local agencies) regulates mining activities in Nevada under regulations

adopted in 1989.

The Regulation Branch has responsibility for protecting waters of the State under the Water

Pollution Control Regulations and has permitting, inspection and closure sections. The

branch issues a Water Pollution Control (WPC) Permit to an operator prior to the construction

of any mining, milling or other beneficiation process activity that uses water from any source

or quality that is biologically, chemically or physically altered because of this use. The

permit is valid for a period of 5 years provided that the operator remains in compliance with

the regulations. A Permit Renewal is required to continue mining operations beyond 5 years.

Prior to submitting a WPC permit application the applicant must meet with division

representatives to discuss the location, operating plans and general characteristics of the

facility. In addition to ownership and facility information the application must include

meteorological information, a complete description of the proposed activity and the

production rate. It must be accompanied by supporting documents on the design,

construction, operation and closure of operations.

The Reclamation Branch issues permits to exploration and mining operations to reclaim

(rehabilitate) the disturbance created to a safe and stable condition that ensures a productive

post-mining land use. An operator must obtain a Reclamation Permit prior to construction of

any exploration, mining or milling activity that proposes to create disturbance over 5 acres or

removes in excess of 36,500 tons of material from the earth.

A surety is to be filed prior to engaging in the activities authorised by the permit. The surety

may be a trust bond, irrevocable letter of credit, corporate guarantee or a combination of these

mechanisms. The surety is reviewed every 3 years to determine if the amount is still adequate

to execute the approved plan for rehabilitation.

In 1994 the US Environment Protection Agency (USEPA) published a Technical Report titled

“Design and Evaluation of Tailings Dams”. The document is intended for government land

managers and the general public and presents the general features of tailings dams and

impoundments “particularly with regard to their ability to mitigate and minimise adverse

March 2002 54


effects to the environment”. Sections of the document have been sourced from the book

“Planning, Design and Analysis of Tailings Dams” by Steven Vick (1990).

The report provides an overview of the methods of tailings disposal and the types of storage

facilities. General information is presented on the design of tailings dams, including a

discussion on design variables, such site-specific factors, site location, hydrology, geology,

ground water, foundations and seismicity. Water control and management, is also presented,

including discussions on hydrology, management of storm flows, infiltration and seepage

control and tailings water treatment.

A case history of the design of a new tailings dam in Montana is presented to illustrate the

work that is required to design a facility and to obtain a permit for mining to commence.

In 1999 EPA Region 10, which includes Alaska, Idaho, Oregon and Washington, issued draft

guidelines for mining operations relative to permitting processes and environmental review

requirements associated with the Clean Water Act (CWA) and National Environmental Policy

Act (NEPA). The document is titled “EPA and Hard Rock Mining: A Source Book for

Industry in the Northwest and Alaska”. It has three objectives as follows:

• Explain the requirements of the CWA and NEPA as they may pertain to new mines.

• Describe the types of information that EPA Region 10 needs to process permit

applications and perform environmental reviews, and

• Promote predictability and consistency within Region 10 to ensure mine development,

operation and closure occur in an environmentally sound manner.

The report includes appendices that describe methods for characterising ore, waste rock and

tailings, mine site hydrology, effluent quality, receiving waters, erosion and sedimentation,

aquatic resources and wetlands and managing wastewater and solid waste.

8.2 South America

8.2.1 Peru

The Political Constitution of Peru establishes the need to protect the environment by

promoting the sustainable use of natural resources. The General Bureau of Environmental

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Affairs has issued protocols and environmental guidelines for implementation of the

environmental policy. These guidelines contain technical standards to be applied in the

design and construction stages of a mining project. Three of these documents refer

specifically to tailings.

The Guide for Mine and Mill Tailings Management (Vick, 1994) aims to present “the broad

and complex issues associated with tailings management… emphasising not only operation

but post-closure conditions”. The document focuses primarily on new mines in Peru and

addresses:

• Tailings management objectives at each life cycle stage of a TSF (Construction,

Operation, Closure and Post-Closure).

• Tailings characteristics including a discussion on the origin of tailings and other solid

wastes, the engineering properties of tailings, chemical characteristics and acid rock

drainage (ARD) from tailings.

• The geography and climate of Peru, highlighting the extreme climatic and seismic

conditions that must be accommodated in the design.

• Alternative methods of tailings disposal including surface TSF, underground backfilling

and submarine tailings disposal. It concludes that surface TSF are most appropriate for

the conditions in Peru.

• Stability is discussed in relation to the types of TSF and the effects and causes of failures.

It is concluded that upstream-type construction is not appropriate for the conditions in

Peru. Analyses are required to assess static stability (in relation to material types,

compaction, filters and drains and foundation materials), seismic stability (liquefaction

and seismic deformations) and hydrological stability of inlet and spillway structures.

• Mitigation of ARD and the control of seepage from surface TSF.

• Rehabilitation and closure of surface TSF - environmental practices in tailings

management must be implemented progressively, with incremental improvements

introduced systematically over time.

March 2002 56


The Heap Leach Projects Guide (Golder, 1994) has as its objective to provide guidance on

the development, construction and operation of heap leach projects in Peru. The guide

addresses:

• Typical heap and dump layouts, including consideration of ore preparation, heap and pad

configurations, solution application and collection, pregnant solution containment and

metal recovery and barren solution containment.

• Surface water hydrology in relation to the climate of Peru (including methods of

computing the peak flow rate) and the calculation of the project water balance.

• Heap leach siting including site and waste characterisation and geologic hazards.

• Containment design including design of the clay and geomembrane liners, and

• Operation and monitoring of performance, and closure.

The Mine Closure Guide (Golder, 1994) provides an outline of closure objectives, approaches

and technical issues for the planning of closure of new mines or new mine facilities (including

TSF). The guide contains tables and text that address the following issues relating to TSF:

• Perpetual disruptive forces and control technologies.

• Chemical stability of soluble minerals, acid drainage and chemical reagents, and control

technologies.

• Design methodologies, including treatment and encapsulation.

• Guidelines for the design of covers.

• Closure alternatives including water management and landfill stability.

• Closure plans for waste materials that address potential environmental issues, typical

closure technologies and typical design elements.

• Post-Closure performance monitoring.

March 2002 57


Other guidelines of relevance to tailings include: Procedures for Preparing the

Environmental Impact Study and Environmental Guidelines for the Handling of Mine Acid

Drainage.

8.2.2 Mexico

The Mexican Official Standard (1997) stipulates the compulsory requirements for site

selection, construction, operation and monitoring of a TSF. These requirements include:

• An environmental impact study.

• Compliance with laws governing the preservation of historical or cultural heritage.

• Assurance that there will be no percolation of toxic leachates to the nearest aquifer or

surface water body within 300 years.

• Approved plans for surface and groundwater monitoring.

• Detailed characterisation of the underlying geological structure and the mechanical

properties of rock formations and soil deposits.

• Land surveys of the site to delineate elevations and features such as roadways and

pipelines.

• Compliance with civil work design standards for dams issued by the Federal Electricity

Commission.

• Monitoring instrumentation for a TSF over 50 m in height.

8.3 Asia

8.3.1 China

In the Peoples Republic of China (PRC) tailings storage facilities must be designed and

constructed in accordance with National Codes (Design Standards). Provincial authorities

are responsible for issuing a license to construct and operate the TSF.

March 2002 58


Code ZBJ 1-90 (1991) Design Standard – Tailings Facility for a Mine, addresses the design

of a TSF for a mine and classifies a TSF into one of five classes according to storage capacity

and dam height. The Code specifies the minimum factor of safety for various operating

conditions. Tables are presented stipulating the minimum freeboard and storage (beach)

length for different classes and types of construction (upstream and centreline), minimum

crest widths and downstream slope angles .

Code GB 50201-94 (1994) Standard for Flood Control, and Code SJD 218-84 (1984)

Standard for Earth and Rockfill Dams stipulates the design return period storm to be used for

the TSF classes and presents design standards for earth and rockfill dams, including

freeboard. Other codes also address aspects of the design of TSF.

Quality criteria for water discharged from the TSF are presented in Code GB 3838-88 (1988)

Quality Standard – Surface Water. The Environmental Protection Department will issue an

Operating Permit. This permit stipulates the location, type and frequency of testing that is

required to verify compliance with the permit.

A Construction and Operating permit has to be obtained before TSF construction can start.

The operator or proponent must submit a Design Report to the Provincial authorities who

convene a Provincial Planning Committee to review and approve the proposals. On

acceptance of the design by the committee a Construction Permit is awarded and work may

commence on site. Periodic inspections are made by relevant authorities during construction

and operation of the facility, during which compliance to various regulations is assessed.

Closure and Rehabilitation Plans are required for the facility and regular inspections are made

during construction and implementation.

The approach adopted in China is one of strict adherence to the national Codes and frequent

inspection and reporting by National, Provincial and District regulatory agencies.

8.3.2 Malaysia

Malaysia’s current mining legislation is limited because it deals almost exclusively with the

small-scale alluvial tin mines that have dominated the county’s mining sector. To attract

foreign investment, Malaysia has proposed new legislation for large-scale hard rock mining.

The proposed legislation includes specific requirements for tailings management such as:

• A design that complies with good engineering practice.

March 2002 59


• Construction under the supervision of a professional engineer.

• Stability against static and dynamic loading.

• A detailed Operating Plan.

• Freeboard of not less than one metre.

• Phase-specific requirements similar to those outlined by the South African Code of

Practice.

8.4 South Africa

Mining in South Africa is regulated by the Water Act, 1998, the Minerals Act, 1991 and the

Mine Health and Safety Act, 1996. The Department of Minerals and Energy (DME) is

responsible for implementing the provisions of the Acts.

A policy of “self management” is applied which requires mines to prepare an Environmental

Management Program Report (EMPR) at the planning stage. Thereafter, the requirements of

the Code of Practice for Mine Residue (SABS 0286-1998) apply to a TSF during its life cycle

stages of design, construction, operation and closure.

The Code of Practice addresses the life cycle of a TSF in terms of safety, construction,

operation and environmental impact. It contains objectives, principles and minimum

requirements for good practice and has the aim of ensuring that no unavoidable risks ,

problems and/or legacies are left to future generations. A process of continual management

and continuous improvement throughout the life cycle is envisaged.

The Code of Practice requires that each TSF be assigned a Safety and Environmental

Classification. In terms of safety each TSF is classified as having a high, medium or low

safety hazard2. The TSF is environmentally classified according to the spatial extent, duration

and intensity of its potential impacts and is considered as either “significant” or “not

significant”. These classifications determine the minimum requirements for investigation,

design, construction, operation and decommissioning of the TSF.

2 Hazard is defined as “the potential to cause harm as a consequence of failure”.

March 2002 60


The code aims to provide control of mining activities from “cradle to grave” and identifies

five phases in the life cycle of a TSF.

• Phase 1: Conceptualisation, Planning and Site Selection requires mine management to

consider alternatives, ensure a sustainable end land use, avoid unnecessary waste and

minimise impacts. Alternatives are to be compared using analytical techniques. TSF of

medium and high hazard classification, or one with a significant environmental impact

component, require a Planning Report.

• Phase 2: Investigation and Tailings Characterisation. Activities include investigation

of the site, characterisation of tailings, assessment of the pre-development environment

and background environmental data and review of alternative impact management

measures. Geotechnical and hydrogeological reports are to be prepared for medium or

high-hazard TSF and baseline environmental data must be included in the mine EMPR.

• Phase 3: Design. The primary design objective is to ensure the reliability and

sustainability of the structural design and the environmental mitigation measures. A

Design Report, an Operating Manual, a Risk Management Report, and approved working

drawings are mandatory. “Best Practice” standards are a minimum requirement. Specific

environmental objectives must be set out and included in the EMPR.

• Phase 4: Construction and Operation. Objectives and personnel/management

requirements are listed for four sub-phases – construction, commissioning, operation and

monitoring and maintenance.

Phase 5: Decommissioning and Aftercare. A Decommissioning and Aftercare Plan for the

TSF must be documented in the EMPR. Aftercare management must include effective design

and mitigation measures for extreme circumstances. Monitoring systems are to be maintained

until the closure objectives are reached.

8.5 Europe

8.5.1 United Kingdom (UK)

Whilst not specifically referencing tailings, TSF construction and operation in the UK are

covered by a number of Acts administered by various government agencies and departments.

Legislation under the Environment Protection Act, 1990 requires an operator of a process

March 2002 61


plant to obtain prior authorisation before a plant can operate. The Water Act, 1989 governs

the discharge of water from a mine site into rivers and the Environmental Protection Act,

1990 requires that a Disposal Licence be obtained for some wastes.

A TSF is classifiable in terms of the Mines and Quarries (Tips) Act, 1971, Part 1 of which

details a comprehensive system of reports and inspections. These regulations require that the

TSF be designed and regularly inspected by a “competent person” and describe the nature and

frequency of reports required. Under Part 2 of the Act the local authority is responsible for

ensuring that disused tips, not associated with active mines or quarries, do not constitute a

danger to members of the public. In addition to these requirements the Reservoirs Act, 1975

requires that an embankment which contains or is designed to retain, more than 25,000 m 3 of

water above the natural level of the adjoining land be registered and regularly inspected.

8.5.2 Other EC Countries

The European Community, including the UK, is bound by EC Directives covering, for

example environmental assessment and water quality. The Directives are implemented by

national legislation that varies from country to country. In Germany each State is responsible

for implementing the regulations. In France mineral extraction and tailings disposal is

covered by the mining code (Code Minier) and local plans (Plan d’Occupation des Sols).

In Portugal, Decree-Law 99/90 controls mining and restoration and operators must enter a

contract with the State and obtain a licence for ancillary operations. Spanish law requires

mines above a given size to lodge a financial guarantee to cover site restoration. In Italy

regulations provide directions for the design, operation and closure of TSF greater than 10 m

in height or for a TSF which in the opinion of the responsible officer, presents a safety risk.

8.6 ICOLD Tailings Dam Guidelines

In 1984 the International Commission on Large Dams (ICOLD) resolved to prepare a set of

guidelines covering all safety, environmental and operational aspects of TSF. The guidelines

are intended to be used by mine operators, those involved in the design, operation and

rehabilitation of TSF and by government agencies responsible for establishing regulations for

the safe design and operation of TSF.

March 2002 62


• Bulletin 74 Tailings Dam Safety – Guidelines discusses the design, operation and

rehabilitation of a TSF and presents recommendations regarding measures that must be

adopted to ensure that the TSF is safe, both during operation and after rehabilitation.

• Bulletin 97 Tailings Dams. Design of Drainage – Review and Recommendations

presents recommendations regarding the provision of drainage in the various types of

TSF, drainage of foundation materials below a TSF, and remedial measures that may be

implemented during operation. Recommendations are also presented regarding the

design of filters and drains.

• Bulletin 98 Tailings Dams and Seismicity – Review and Recommendations covers

seismic aspects of the design of a new TSF and safety evaluations of an existing TSF.

The bulletin addresses those aspects of design pertaining to seismic stability.

• Bulletin 101 Tailings Dams. Transport, Placement and Decantation – Review and

Recommendations recognises that the majority of TSF failures have been due to an

excessive rise of water level causing the phreatic surface to reach the downstream slope

or even pass over the crest of the embankment. The bulletin describes methods for

assessing the TSF water balance and presents recommendations regarding the design of

various types of discharge systems.

• Bulletin 103 Tailings Dams and the Environment – Review and Recommendations

addresses TSF design and operation and their impact on the environment. It considers

environmental impact assessments that must be prepared at the planning stage and

discusses issues controlling environmental stability during the operating, rehabilitation

and post-closure phases of the TSF life cycle. Recommendations are presented for the

monitoring of operations and for the environmental rehabilitation of a TSF.

• Bulletin 104 Monitoring of Tailings Dams – Review and Recommendations discusses

approaches to the instrumentation of a TSF. Recommendations are presented regarding

the measurement of seepage, water pressures, displacement and seismic loadings on a

TSF.

• Bulletin 106, A Guide to Tailings Dams and Impoundments – Design, Construction, Use

and Rehabilitation presents principles for the design of safe TSF, control and operation

procedures, comments on remedial works that may be necessary and a chapter on the

March 2002 63


design of rehabilitation measures for a TSF. A chapter discusses governmental

regulations controlling a TSF in some countries.

The ICOLD bulletins present general advice on TSF design, operation and rehabilitation and

provide a starting point for the development of management systems.

March 2002 64


9 AUSTRALIAN MINING GUIDELINES, CODES AND STANDARDS

9.1 Western Australia

For all mining projects in Western Australia a Notice of Intent (NOI) document addressing

the environmental issues associated with the mining project has to be submitted in accordance

with the “Guidelines to Help you get Environmental Approval for Mining Projects in Western

Australia” (DME3, 1998). The NOI should contain a Design Report that documents the

design of the TSF. The design should be carried out in accordance with the “ Guidelines on

the Safe Design and Operating Standards for Tailings Storage” (DME, 1999). The TSF

design is assessed by the DME and, for “ environmentally significant” projects, also by the

DEP3. The design is required to take cognisance of development, operational and

rehabilitation/closure conditions. The DME Guidelines set out minimum requirements in this

regard.

All TSF in Western Australia are categorised as a Category 1, 2 or 3 facility. The TSF

categorisation is based on its “hazard rating”, coupled with the maximum embankment

height. All TSF over 15 m in height are considered to be Category 1 facilities, ie those

requiring the most stringent attention.

Under the provisions of Part V of the Environmental Protection Act, 1986, a Works Approval

may be required from the Pollution Prevention Division of the DEP before any construction

begins. For a Category 1 or 2 TSF construction is to be certified by a suitably qualified

person to have been carried out in accordance with the NOI design. A Construction Report

should be submitted to the DME.

An Operating Licence may also be required from the DEP before the TSF can commence

operation (as it may be considered to be part of the processing plant). Operating licences

usually stipulate specific conditions to be adhered to during the various stages of the TSF

development and closure. An annual environmental audit is normally required. Operation is

to be carried out in accordance with the DME Guidelines on the Safe Design and Operating

Standards for Tailings Storage and a site-specific Operating Manual is required for every

TSF. The manual should be prepared in accordance with the Guidelines on the Development

3 Department of Environmental Protection, Western Australia

March 2002 65


of an Operating Manual for Tailings Storage (DME, 1999). It is a requirement to periodically

review and update operating manuals.

Written approval is also required from Water and Rivers Commission under by-laws of the

Country Areas Water Supply Act, 1947 on projects that pose a threat to water resource quality.

This requires compliance with the principles set down in the draft “Water Quality Protection

Guidelines – Tailings Facilities” (Water and Rivers Commission, 1999).

As most TSF are greater than 1 Ha in extent and invariably result in a change in land use, a

“Notification of Intention to Clear Land” is required under the Soil and Land Conservation

Act, 1945. This is to be submitted as part of the Notice of Intent (NOI).

The DME require periodic technical audits to be carried out during the operational phase on

all TSF. The Guidelines on the Safe Design and Operating Standards for Tailings Storage

and the Guidelines on the Development of an Operating Manual for Tailings Storage contain

requirements in this regard. An Audit Report is to be submitted annually for Category 1

facilities, every two years for Category 2 facilities and every three years for Category 3

facilities. In addition, an Emergency Plan and a Decommissioning Plan are required for the

TSF.

9.2 Queensland

The Queensland Environmental Resources Act, 1989 requires environmental impacts to be

addressed and managed during all mining and rehabilitation activities. The Department of

Minerals and Energy (DME) has developed an Environmental Management Policy for Mining

in Queensland which seeks to develop eventual self-regulation with respect to environmental

management. The regulations require that proponents and mine management prepare an

Environmental Management Overview Strategy (EMOS) which is a comprehensive and

strategic environmental management plan for the life of a mining project. Regular Plans of

Operations are prepared with the objective of achieving the environmental commitments,

including protecting the environment and rehabilitating environmental disturbances to agreed

standards.

The DME in association with other government departments, the Queensland Mining Council

and tertiary education institutions prepared the “Technical Guidelines for the Environmental

March 2002 66


Management of Exploration and Mining in Queensland” (DME4, 1995). The objectives of

the Technical Guidelines are:

• To provide advice about mine planning, water management and rehabilitation and assist

the mining industry to manage mining and rehabilitation activities so as to satisfy the

environmental objectives of the Act and the Environmental Management Policy.

• To assist proponents and operators to prepare the EMOS, Plans of Operations and

Environmental Audit documents.

A TSF which contains hazardous substances or which exceeds stipulated storage capacity

criteria, is defined as a Referable Dam under the Water Resources Act, 1989 and must be

licensed. Most TSF are Referable Dams. The Act requires that Referable Dams be designed

and their construction supervised by suitably qualified and experienced persons. The method

of operation may be stated in the licence and operation of such a dam must be carried out by

the owner in terms of the licence conditions.

Discharges of water from mine sites into water bodies and waterways is controlled by the

Environment Protection Act, 1994. A licence must be obtained if water is to be deliberately

discharged, which defines the flows of all wastes to waters (as defined in the Act). The

licence will satisfy the receiving water standards described in the Environmental Protection

(Water) Policy 1995. The TSF is expected to be constructed and managed such that water

discharged to waterways will be a rare event or of such a quality as not to significantly impact

receiving waters. A license is not required if these criteria are satisfied.

The Technical Guideline document is divided into three sections dealing with Mine Planning,

Water Management and Rehabilitation. It contains thirty one guidelines: fourteen in the Mine

Planning section, five in the Water Management section and twelve in the Rehabilitation

section. A further four guidelines are still to be issued. One guideline, Tailings Management,

addresses tailings management and discusses the planning, design and operation of tailings

management systems and a TSF.

In mid 1999 the Queensland Government approved the transfer of the environmental

regulation of the mining industry in Queensland from the DME to the State’s Environmental

Protection Agency. It is understood that Environmental Regulation mechanisms for mining in

Queensland are currently under review.

4 Department of Mines and Energy, Queensland.

March 2002 67


9.3 New South Wales

In New South Wales two principal Acts control the development and operation of mines – the

Mining Act, 1992 and the Environmental Planning and Assessment Act, 1979. In addition

there is a wide range of other legislation administered by up to 30 specialist government

departments and agencies.

The Mining Act, 1992 provides the Department of Mineral Resources (DMR) with powers in

respect of the control of exploration and mining methods, the disposal of mining wastes and

the rehabilitation of land disturbed by mining and associated activities. Two instruments of

approval are required before mining can commence: the Mining Lease; and the Development

Consent. Section 65(3) of the Act provides that the DMR can attach conditions to the Mining

Lease relating in part to mining methods to be used and rehabilitation of land disturbed by

mining. The Development Consent relates to interactions between the mine and surrounding

land uses and communities. A security deposit must be lodged with the DMR to cover

possible non-rehabilitation of mining land. The amount of the deposit is based on the cost to

the DMR to complete full rehabilitation of all disturbance on site. The level of the security is

subject to periodic review.

At design stage Rehabilitation Plans must be provided to the DMR addressing pre-mining and

post-mining land forms and drainage patterns, and proposals for final land use, revegetation

and soil erosion control. During operation the company must submit to the DMR an annual

Environmental Management Plan (EMP) which addresses environmental issues related to

impacts of mining and issues such as water management, dust control and pollution control

measures.

In terms of the Environmental Planning and Assessment Act, 1979 mining projects are treated

as designated developments. The Act details the content of environmental impact statements

(EIS) which are required at the start of the approvals process. A Works Approval application

must be submitted to the EPA. This document must include engineering specifications

showing the design of the mine and of the waste disposal systems. The EPA issue permits

and licences for mining and require periodic technical audits to be carried out during the

operation phase on all facilities. Licences are also required before a mine may discharge to

waterways and the atmosphere under the Clean Air Act, 1961 and the Clean Waters Act,

1970.

March 2002 68


The NSW Coal Association issued a guideline Mine Rehabilitation – A Handbook for the

Coal Mining Industry (1995). This document provides information on the development of a

successful rehabilitation programme. Advice is provided on rehabilitation planning, soils and

topsoiling, erosion control, drainage and sediment control and revegetation and maintenance

of revegetated areas.

9.4 South Australia

The Department of Mines and Energy of South Australia (MESA) is responsible for

regulating tailings disposal in South Australia. The department proposes an objective-based,

regulatory regime in which MESA monitors the performance of the mining industry against

established objectives. Proponents and operators are responsible for determining and

implementing procedures and auditable management systems to achieve the established

objectives. Regulatory objectives currently are expressed in terms of outputs and efficiency

but will gradually be amended to objectives expressed in terms of outcomes and

effectiveness. Criteria for measuring the achievement of objectives are being developed and

MESA is evaluating a method of measuring industry achievement of environmental

objectives known as Goal Attainment Scaling. Environmental management systems must be

auditable against some recognised standard or benchmark, although MESA does not request

or require accreditation to a specific management system.

We understand that MESA is currently considering the adoption of a regulatory system

similar to that currently in use in Western Australia.

9.5 Tasmania

Tailings storage in Tasmania is regulated in terms of the Water Act, 1957, the Environmental

Management and Pollution Control Act, 1994 and the Land Use Planning and Approval Act,

1993. The Department of Primary Industries, Water and the Environment implements the

Acts. Proponents and operators must obtain a Permit from the Department for a new TSF or

to raise an existing TSF. The permit application shall include an Environmental Management

Plan and an Operating Plan. Mineral Resources Tasmania and the Rivers and Water Supply

Commission assess engineering aspects of the design. If the design is satisfactory an

Approval for Construction Notice is issued, usually with conditions requiring a Completion

Report to be submitted by the designer on completion of construction and surveillance audits

to be undertaken at least every five years.

March 2002 69


A dam will be registered on the Dam Safety Register if it contains in excess of 2,500 m 3 of

water. All TSF are therefore registered.

9.6 Northern Territory

The Northern Territory Department of Mines and Energy is responsible for regulating TSF

construction, operation and closure. Part 15 of the Mine Management Act, states that

construction or modification of a dam to store tailings or water shall not commence without

the approval of the Chief Government Mining Engineer (CGME). The manager of the mine

shall supply the CGME with a Design Report and details of the proposed method of

construction. Approval to commence construction is provided by the Department, usually by

a Letter of Approval. Conditions are usually appended to the approval requiring a Certificate

of Completion to be submitted by the designer of the TSF on completion of construction and

stipulating requirements for monitoring of groundwater quality and the rate of seepage during

operation of the TSF. Part 5 of the Act requires that the mine manager submit to the CGME

for approval plans and reports on rehabilitation, water management and monitoring programs

at the mine.

9.7 Nuclear Waste Guidelines

In 1987 The Department of the Arts, Sport, the Environment, Tourism and Territories

(DASETT) issued a guideline for the decommissioning and rehabilitation of uranium mine,

mill and waste disposal sites. The guideline includes the Code of Practice on the

Management of Radioactive Wastes from the Mining and Milling of Radioactive Ores

(DASETT, 1982). The Code sets out three basic requirements for the rehabilitation of sites

where radioactive ores has been mined as follows:

• The sites shall be rehabilitated in accordance with an approved waste management

program and to the satisfaction of the appropriate authority.

• The waste management system shall utilise the Best Practicable Technology and shall

ensure that the release of radioactive material shall be minimised.

• Rehabilitation shall be such that the need for subsequent inspection, monitoring and

maintenance is minimised and preferably rendered unnecessary.

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The Code contains chapters on the objective of decommissioning and rehabilitation,

performance criteria, strategies for decommissioning, a strategy for rehabilitation and

requirements for preparing a Decommissioning and Rehabilitation Plan.

The plan should include the following information for the uranium TSF:

• Properties, quantities and location of materials to be used for rehabilitation.

• Details of the cover structure (layers).

• Expected settlement of the tailings.

• Profile of the surface of the cover and allowance for settlement.

• Methods of discharging rainwater run-off.

• Expected location of the phreatic surface in the TSF, prior to rehabilitation and in the long

term.

• Assessment of the rates of radon exhalation and gamma ray emission over the surface of

the rehabilitated TSF.

• The expected life of the cover structure and the basis of the prediction.

9.8 ANCOLD Tailings Guidelines

The Australian National Committee on Large Dams (ANCOLD) issued Guidelines on

Tailings Dam Design, Construction and Operation in 1999. The document contains

guidelines on the approach to TSF planning, design, management, construction, operation and

closure. The document presents objectives of a planned approach to tailings storage and notes

that continuous management is a fundamental principle in the planning of TSF.

The process proposed by ANCOLD is consistent with world’s best practice and anticipates

the following outcomes:

• Identification of hazards and risks, leading to an appropriate classification of the TSF.

March 2002 71


• The selection, construction and commissioning of a suitable storage system.

• Identification and scheduling of capital cost and construction requirements.

• Provision of Operating and Management Manuals for both day to day and long term

management.

• Ensuring compliance with environmental requirements and long term rehabilitation.

• The efficient filling of disposal areas.

• Performance monitoring of the disposal systems.

• Incorporation of flexibility and the ability to accommodate change.

• Identification and attention to the effects of changes, whether planned, accidental or

unforeseen.

• Ensuring long term goals of total storage needs, closure and decommissioning are met.

The document outlines the approach, concepts, principles and requirements to achieve the

above outcomes. Alternative strategies that may be considered for a particular situation are

described. Some minimum design criteria pertaining to freeboard and slope stability are

recommended.

9.9 Environment Australia (Commonwealth) – Best Practice Environmental

Management in Mining

Environment Australia’s (EA) Environment Protection Group (EPG), formerly the Environment

Protection Agency (EPA), has prepared a series of Best Practice Environmental Management in

Mining modules (guides). These documents are designed to provide developers and contractors

with guidelines on how to implement sound practices that minimise environmental impacts and

reduce the impacts of mining by following the principles of ecologically sustainable

development. Modules of particular relevance to TSF include:

• Tailings Management (EPA, 1995) which presents advice on Best Practice Environmental

Management for the various life cycle stages of a TSF: planning, design, operation and

March 2002 72


closure. Discussions are presented on selecting the site, preparing the design, operating and

monitoring the TSF and closure.

• Managing Sulphidic Mine Wastes and Acid Drainage (EPG, 1997). This module asserts

that acid rock drainage5 (ARD), because of its potential for long term environmental

degradation, is one of the biggest environmental issues facing the mining industry. The

module presents information on factors influencing ARD, implications of ARD for mine

operators, the prediction and identification of acid drainage and the management of

sulphide oxidation. Various treatment strategies are discussed.

• Cyanide Management (EPG, 1998) considers issues relating to the control of cyanide. The

module presents an overview of cyanide chemistry and methods of minimising

environmental impacts.

• Landform Design for Rehabilitation (EPG, 1998) discusses approaches to be considered in

the closure and rehabilitation of TSF. Design criteria and approaches are discussed in

relation to in-pit disposal of spoil and waste rock and surface spoil and waste rock dumps.

• Environmental Risk Management (EPG, 1999) (ERM) presents advice on ERM methods for

the mining industry. Information is presented on hazard identification, risk analysis, and

risk reduction/minimisation. ERM is increasingly applied as a condition in Operating

Licences and its use in mining is expected to grow in importance.

It is noted that mining can never have zero environmental impact since there is always some

uncertainty regarding the type and extent of possible adverse consequences and their

probability of occurrence. Risk analysis studies will identify hazards and provide a basis for

judging the effectiveness of existing operational procedures and systems to address the

hazards. An example of a hazard identification diagram for a tailings storage is presented

and lists possible initiating events and consequences. The analysis also provides

opportunities for identifying ways to reduce risk. It is argued that risk reduction be adopted

as an objective of ERM and options providing the lowest levels of risk be pursued wherever

feasible – the ALARP [As Low As Reasonably Practical] concept. Sensitivity analyses

allow the implications of changes to assumptions and limitations to knowledge to be

considered. Examples of possible risk reduction measures for tailings storages are given in

the hazard identification diagram referred to above.

5 Sometimes referred to as Acid Mine Drainage (AMD)

March 2002 73


Risk analysis may be qualitative or quantitative and sound analysis includes both

components. Various forms of analysis are discussed. Matrices are frequently used to rank

hazards for the degree of likelihood and consequence and an example is presented in

AS/NZS 4360:1999 Risk Analysis. Fault tree and event tree methods are useful methods

for evaluating the likelihood and consequences of hazards. The method is particularly

suited to use in sensitivity analyses. A simplified fault tree for the release of contaminated

water from a tailings storage and an event tree for the impact of runoff water on a tailings

storage is presented.

The modules highlight issues to be considered and present a series of case histories showing

the implementation of best practice in diverse environments across Australia.

March 2002 74


10 BIBLIOGRAPHY

10.1 Guidelines, Codes and Accepted Good Practice

ANCOLD (1998) Draft Guidelines on Tailings Dam Design, Construction and Operation,

August.

ANCOLD (1996) Interim Guidelines for Design of Dams for Earthquake, November.

ANZECC (1998) “Interim Ocean Disposal Guidelines”.

AS/NZS 4360:1999 Risk Management.

Chamber of Mines South Africa (1996) Guidelines for Environment Protection Volume 1

“The Engineering Design, Operation and Closure of Metalliferous, Diamond and Coal

Residue Deposits”.

Department of Minerals and Energy (Western Australia) (1999) Guidelines on the Safe

Design and Operating Standards for Tailings Storage, May.

Department of Minerals and Energy (Western Australia) (1998) Guidelines to Help get

Environmental Approval for Mining Projects in Western Australia, March.

Department of Minerals and Energy (Western Australia) (1998) Guidelines on the

Development of an Operating Manual for Tailings Storage. ISBN 0 7309 7805 2.

Department of Minerals and Energy (Western Australia) (1996) Guidelines for Mining in Arid

Environments, June.

Department of Minerals and Energy (Queensland) (1995) Technical Guidelines for the

Environmental Management of Exploration and Mining in Queensland. Queensland

Government. ISBN 0 7242 5260 6.

Environment Australia (1999) Best Practice Environmental Management in Mining

“Environmental Risk Management” ISBN 0 642 54630 4.

March 2002 75


Environment Australia (1998) Best Practice Environmental Management in Mining “Cyanide

Management” ISBN 0 642 54563 4.


“Landform Design for Rehabilitation” ISBN 0 642 54546 4.


“Managing Sulphidic Mine Waste and Acid Drainage” ISBN 0 642 19449 1.


“Rehabilitation and Revegetation” ISBN 0 642 19420 3.

Environment Australia (1995) Best Practice Environmental Management in Mining “Tailings

Management” ISBN 0 642 19423 8.

Golder Associates Ltd (1994) Mine Closure Guide. Ministry of Energy and Mines – Peru.

Golder Associates Ltd (1994) Heap Leach Projects Guide. Ministry of Energy and Mines –

Peru.

Hannan J. C. (1995) Mine Rehabilitation. A Handbook for the Coal Mining Industry. 2nd Ed.

The New South Wales Coal Association, Sydney.

ICOLD (1996) A Guide to Tailings Dams and Impoundments. Bulletin 106. Paris.

ISSN 0534-8293

ICOLD (1996) Tailings Dams and Environment – Review and Recommendations.

Bulletin 103.Paris. ISSN 0534-8293

ICOLD (1996) Monitoring of Tailings Dams –Review and Recommendations. Bulletin 104.

Paris. ISSN 0534-8293

ICOLD (1995) Tailings Dams and Seismicity – Review and Recommendations.

Bulletin 98.Paris. ISSN 0534-8293

ICOLD (1995) Tailings Dams. Transport Placement and Decantation – Review and

Recommendations. Bulletin 101.Paris. ISSN 0534-8293

March 2002 76


ICOLD (1994) Tailings Dams Design of Drainage – Review and Recommendations.

Bulletin 97. Paris. ISSN 0534-8293

ICOLD (1989) Tailings Dam Safety - Guidelines. Bulletin 74.Paris. ISSN 0534 8293

Mine Metallurgical Managers’ Association of South Africa (1995 ) The Management of Gold

Residue Deposits - A Code of Practice. 30 March.

Saskatchewan Environment and Public Safety Mines Pollution Control Branch Mine Rock

Guidelines. Design and Control of Drainage Water Quality Report 93301 prepared by

Steffen Robertson and Kirsten.

The Mining Association of Canada (1998) A Guide to the Management of Tailings Facilities.

Ottawa.

The South African Bureau of Standards (1999) Code of Practice for Mine Residue Deposits.

SABS 0286:1998. ISBN 0-626-11700-3

US EPA (1994) Technical Report. Design and Evaluation of Tailings Dams. EPA 530.R.94

US EPA Region 10 (1999) EPA and Hard Rock Mining: A Source Book for Industry in the

Northwest and Alaska, EPA 910-R-99-016

Vick S. (1994) Guide for Mine and Mill Tailings Management Ministry of Energy and Mines,

Government of Peru.

March 2002 77


10.2 Papers and Books

Duncan, J. S., (Eds) (1982) Atlas of Victoria, Government of Victoria.

Robinski, EI (1975) Thickened Discharge – a New Approach to Tailings Disposal. Bulletin of

Canadian Institute of Mining and Metallurgy.

Blight, GE (1994) The Master Profile for Hydraulic Fill Tailings Beaches. Proc ICE

Geotechnical Engineering Vol 107, pp27-40.

Jones, S (1996) Potential for Submarine Tailing Disposal in the Asia Pacific Region.

Minerals Council of Australia Environmental Workshop, Newcastle, October.

International Council on Metals and the Environment (1998) Case Studies on Tailings

Management. United Nations Environment Programme (UNEP), Paris. ISBN

1-895720-29-X

Landriault D, Welch D and Morrison D (1996) Mine Tailings Disposal as a Paste Backfill for

Underground Mine Backfill and Surface Waste Deposition. Society for Mining,

Metallurgy and Exploration, Inc. Short Course. Ontario.

Down C. G. and Stocks J. (1975) The Environmental Problems of Tailings Disposal at Metal

Mines. Department of the Environment Research Report 17. HMSO.

Lo R. and Klohn E. J. (1990) Seismic Stability of Tailings Dams. International Symposium on

Safety and Rehabilitation of Tailings Dams. ICOLD. Sydney.

Malavazos M. (1998) Goal Attainment Scaling: A Tool for Measuring Objectives.

Environmental Assessment of Abandoned Petroleum Wellsites in the Cooper Basin,

South Australia. Mines and Energy Resources, South Australia.

Kurzeme M. (1986) Surface Disposal of Tailings in Australia. Workshop on Mine Tailings

Disposal, University of Queensland, Brisbane.

Nicholson R, Gillham R., Cherry J. and Reardon E. (1989) Reduction of Acid Generation in

Mine Tailings Through the Use of Moisture-Retaining Cover Layers as Oxygen

Barriers Canadian Geotechnical Journal. 26, 1-8.

March 2002 78


Peyton L. and Schroeder P. R. (1990) Evaluation of Landfill-Liner Designs Journal of

Environmental Engineering. Vol. 116, No. 3, May/June.

Fergusson K. A., Hutchinson I. P. and Schiffman R. L. (1985) Water Balance Approach to

Prediction of Seepage from Mine Tailings Impoundments in Seepage and Leakage from

Dams and Impoundments. Ed. Richard Volpe and William Kelly. ASCE Symposium,

Denver.

Hossein M., Hassani F. and Leduc R. (1993) A Brief Survey of Current Surface Waste

Disposal Practices in the Metal Mining Industry. Int. Journal of Surface Mining and

Reclamation. 7(1993):23-28.

Smith A. and Mudder T. (1992) Chemistry and Treatment of Cyanide Wastes. Mining Journal

Books Ltd. London.

South African Institute of Mining and Metallurgy and Association of Mine Managers of

South Africa (1988) Backfill in South African Mines. Special Publication Series SP2.

ISBN 0 620 117885 5

Vick S (1990) Planning, Design and Analysis of Tailings Dams. BiTech Publishers,

Vancouver

Williams DA (1999) Risk Analysis to Facilitate Decision-Making in Tailings Design Proc

ICM Conf on Tailings Storage Management, Perth, 11-12 October

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