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KOOLAN ISLAND IRON ORE
MINE AND PORT FACILITY
Conceptual Closure Plan
ecologia
ENVIRONMENT
Koolan Island Iron Ore Mine and Port Facility
Conceptual Closure Plan
Document Status
Rev
Author
No.
Final
K. Bleby
R. Mason
Reviewer/s
Date
V Ee
Nov 05
Approved for Issue
Name
Distributed To
Dudley
EPA
Kingsnorth
Date
Nov 05
© ecologia Environment (2005). Reproduction of this report in whole or in part by electronic, or
mechanical means including photocopying, recording or by any information storage and retrieval system,
in any language, is strictly prohibited without the express approval of Aztec Resources Limited and/or
ecologia Environment.
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Conceptual Closure Plan
CONTENTS
SUMMARY
5
1.0
6
1.1
1.2
1.3
1.4
INTRODUCTION
PREVIOUS OPERATIONS ........................................................................................................................7
CURRENT OPERATIONS .........................................................................................................................8
PLANNED OPERATIONS .........................................................................................................................8
PROJECT CLOSURE PLAN SCOPE ..........................................................................................................9
2.0
PROJECT CLOSURE OBJECTIVES
14
3.0
LEGAL OBLIGATIONS
15
3.1
3.2
4.0
4.1
4.2
5.0
5.1
5.2
6.0
6.1
6.2
7.0
7.1
7.2
8.0
8.1
8.2
8.3
9.0
9.1
9.1.1
9.1.2
9.1.3
9.2
9.2.1
9.2.2
9.2.3
9.3
9.3.1
9.3.2
9.3.3
9.4
9.4.1
9.4.2
9.4.3
9.5
9.5.1
9.5.2
9.5.3
LEGISLATION .......................................................................................................................................15
GUIDELINES AND CODES OF PRACTISE ..............................................................................................16
COMPLETION CRITERIA
17
OBJECTIVE...........................................................................................................................................17
PROPOSED COMPLETION CRITERIA ...................................................................................................17
CONTAMINATED SITES
19
OBJECTIVE...........................................................................................................................................19
CONTAMINATED SITES INVESTIGATION AND MANAGEMENT............................................................19
DECOMMISSIONING
21
OBJECTIVE...........................................................................................................................................21
REMOVAL OF INFRASTRUCTURE ........................................................................................................21
DEVELOPMENT OF FINAL LANDFORMS
23
OBJECTIVE...........................................................................................................................................23
SHAPING OF LANDFORMS....................................................................................................................23
REHABILITATION STRATEGIES
25
OBJECTIVES .........................................................................................................................................25
REHABILITATION ................................................................................................................................25
MONITORING OF REHABILITATION ....................................................................................................26
PROPOSED CLOSURE STRATEGIES
27
MINE PITS ............................................................................................................................................27
CLOSURE OBJECTIVE .............................................................................................................................27
CLOSURE STRATEGY ...............................................................................................................................27
COMPLETION CRITERIA ..........................................................................................................................28
SEAWALL .............................................................................................................................................30
CLOSURE OBJECTIVE ............................................................................................................................30
CLOSURE STRATEGY .............................................................................................................................30
COMPLETION CRITERIA.........................................................................................................................30
WASTE ROCK MANAGEMENT .............................................................................................................30
CLOSURE OBJECTIVE .............................................................................................................................31
CLOSURE STRATEGY ...............................................................................................................................31
COMPLETION CRITERIA ..........................................................................................................................32
BORROW PITS ......................................................................................................................................32
OBJECTIVES ...........................................................................................................................................32
CLOSURE STRATEGY ...............................................................................................................................32
COMPLETION CRITERIA ..........................................................................................................................32
DEWATERING ......................................................................................................................................33
OBJECTIVES ...........................................................................................................................................33
CLOSURE STRATEGY ...............................................................................................................................33
COMPLETION CRITERIA ..........................................................................................................................33
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9.6
9.6.1
9.6.2
9.6.3
9.7
9.7.1
9.7.2
9.7.3
9.8
9.8.1
9.8.2
9.8.3
9.9
9.9.1
9.9.2
9.9.3
9.10
9.10.1
9.10.2
9.10.3
9.11
9.11.1
9.11.2
9.11.3
9.12
9.12.1
9.12.2
9.12.3
9.13
9.13.1
9.13.2
9.13.3
9.14
9.14.1
9.14.2
9.14.3
9.15
9.15.1
9.15.2
9.15.3
10.0
10.1
10.2
11.0
11.1
11.2
12.0
12.1
12.2
14.0
HAUL ROADS, ROM PAD, STOCKPILE AND ORE PROCESSING .........................................................34
OBJECTIVE ............................................................................................................................................34
CLOSURE STRATEGY ...............................................................................................................................34
COMPLETION CRITERIA ..........................................................................................................................34
JETTY AND SHIP LOADER ....................................................................................................................34
OBJECTIVE ............................................................................................................................................35
CLOSURE STRATEGY ...............................................................................................................................35
COMPLETION CRITERIA ..........................................................................................................................35
POWER STATION .................................................................................................................................35
OBJECTIVE ............................................................................................................................................35
CLOSURE STRATEGY ...............................................................................................................................35
COMPLETION CRITERIA ..........................................................................................................................36
FUEL AND BULK STORAGE FACILITIES ..............................................................................................36
OBJECTIVE ............................................................................................................................................36
CLOSURE STRATEGY ...............................................................................................................................36
COMPLETION CRITERIA ..........................................................................................................................36
WORKSHOPS ........................................................................................................................................37
OBJECTIVE ............................................................................................................................................37
CLOSURE STRATEGY ...............................................................................................................................37
COMPLETION CRITERIA ..........................................................................................................................37
EXPLOSIVE STORAGE ..........................................................................................................................38
OBJECTIVE ............................................................................................................................................38
CLOSURE STRATEGY ...............................................................................................................................38
COMPLETION CRITERIA ..........................................................................................................................38
LANDFILL.............................................................................................................................................38
OBJECTIVE ............................................................................................................................................39
CLOSURE STRATEGY ...............................................................................................................................39
COMPLETION CRITERIA ..........................................................................................................................39
BIOREMEDIATION FACILITY ...............................................................................................................40
OBJECTIVES ...........................................................................................................................................40
CLOSURE STRATEGY ...............................................................................................................................40
COMPLETION CRITERIA ..........................................................................................................................40
ACCOMMODATION ..............................................................................................................................41
OBJECTIVES ...........................................................................................................................................41
CLOSURE STRATEGY ...............................................................................................................................41
COMPLETION CRITERIA ..........................................................................................................................41
ADMINISTRATION OFFICES .................................................................................................................42
OBJECTIVE ............................................................................................................................................42
CLOSURE STRATEGY ...............................................................................................................................42
COMPLETION CRITERIA ..........................................................................................................................42
PUBLIC ACCESS AND SAFETY ASPECTS
43
OBJECTIVES .........................................................................................................................................43
STRATEGY............................................................................................................................................43
RECORDS MANAGEMENT AND REPORTING SCHEDULES
44
OBJECTIVE...........................................................................................................................................44
STRATEGY............................................................................................................................................44
MONITORING
45
OBJECTIVES .........................................................................................................................................45
STRATEGY............................................................................................................................................45
SUMMARY OF MANAGEMENT ACTIONS
REFERENCES
47
55
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FIGURES
1.1A
1.1B
1.2
1.3
9.1
PROPOSAL STUDY REGION .................................................................................................................11
PROJECT LOCATION............................................................................................................................11
BHP MINING OPERATIONS AT ARBITRATION COVE PRIOR TO 1993 (TOP FOUR PHOTOS) AND A
VIEW OF ARBITRATION COVE AT PRESENT (JULY 2004) ...................................................................12
PROPOSED OPERATIONS ON KOOLAN ISLAND ....................................................................................13
LAYOUT ON KOOLAN ISLAND .............................................................................................................29
TABLES
1.1
14.1
SUMMARY OF KEY CHARACTERISTICS ASSOCIATED WITH THE PROPOSAL.....................................10
SUMMARY OF MANAGEMENT ACTIONS..............................................................................................47
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SUMMARY
Site closure, either at the end of the mine life or running concurrently with mining activities is a
critical component of mine management and is important in regard to public perception of
mining activities. In accordance with the Mine Closure Policy (Minerals Council of Australia,
2000) the primary objective for mine closure is “to leave the site in a condition which is safe,
stable and limits further environmental impacts so that mining tenements can be relinquished for
alternative land use.”
Aztec Resources Ltd (Aztec) are proposing to re-establish an iron ore mine on Koolan Island.
BHP mined iron ore on Koolan Island between 1965 and 1993. On May 30 2003, the Minister
for State Development granted Aztec authorisation to explore for iron ore on Koolan Island.
Aztec sought and obtained environmental approval under a Notice of Intent (NOI) to commence
exploration activities on the island in February 2004. Feasibility studies to investigate the
viability of a mining and processing operation have commenced. These include environmental
baseline surveys of the island, the results of which will be used to develop environmental
management plans for the project. Aztec aims to complete feasibility studies and commence
construction in early 2006. It is envisaged that production will begin by the early 2007, at a rate
of 2-4 million tonnes per annum with a strip ratio of 6:1, and life in excess of nine years.
A conceptual closure plan is to be submitted as part of the documentation for environmental
approval. By developing a closure plan as part of the planning stages of the project Aztec can
demonstrate that the site can be closed in a manner acceptable to regulators and post-mining
land users.
Planning for mine closure seeks to address the social, environmental, financial and safety aspects
of mine closure. The aim is to prevent or minimise long-term environmental impacts and to
create a self-sustaining natural ecosystem or alternate land use based on an agreed set of
objectives (ANZMEC, 2000). In undertaking mine closure activities at Koolan Island, Aztec
will fulfil the following objectives:
•
Protect public safety;
•
Minimise environmental and socio-economic impacts;
•
Meet legislative requirements;
•
Enable all stakeholders to have their interests considered during the mine closure
process;
•
Re-establish self-sustaining ecosystems compatible with post-mining land use
requirements;
•
Establish stable landforms that are sympathetic with the regional landforms and
geotechnically stable;
•
Develop completion criteria to enable relinquishment to occur;
•
Undertake monitoring until agreed completion criteria are achieved;
•
Fulfil commitments in the Closure Plan; and
•
Release the operator from further liability.
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Conceptual Closure Plan
1.0
INTRODUCTION
Koolan Island is one of the many islands comprising the Buccaneer Archipelago off the
Kimberley Coast. It is located 130 km north east of Derby at the northern end of the Yampi
Peninsula. It is separated from the mainland by a 1 km wide channel. The waters surrounding
Koolan Island are a proposed marine conservation reserve under the CALM Act (CALM, 1994).
Koolan Island is one of three islands hosting the Yampi Sound iron ore deposits (Figure 1.1a &
1.1b).
Aztec Resources Ltd (Aztec) are proposing to re-establish an iron ore mine on Koolan Island.
BHP mined iron ore on Koolan Island between 1965 and 1993. During this period
approximately 68 million tonnes of high-grade haematite ore was extracted from five pits,
crushed and shipped from a wharf facility. Decommissioning of the mine in 1993 included the
removal (some in situ burial) of infrastructure associated with BHP operations, rehabilitation of
cleared areas by moon scaping, and the construction of a channel to allow seawater flooding of
the Main pit.
On May 30 2003, the Minister for State Development granted Aztec the authorisation to explore
for iron ore on Koolan Island under exploration licence 04/1266. Aztec sought and obtained
environmental approval under a Notice of Intent (NOI) to commence exploration activities on
the island in February 2004. Subsequent to the initial NOI approval, two amendments have been
submitted and approved to increase the scope of the exploration activities.
Aztec aims to complete feasibility studies by mid 2005 and commence construction in early
2006. It is envisaged that production will commence by the early 2007, at a mining rate of 2-4
million tonnes of ore per annum with a strip ratio of 6:1, and life of more than nine years.
This Conceptual Closure Plan is to be submitted as part of the documentation for environmental
approval. As mining is a transient land use it is important that closure and rehabilitation
strategies are incorporated into all aspects of the mine development from initial mine planning
and through the life of the mine. By developing a closure plan as part of the planning stages of
the project Aztec can demonstrate that the site can be closed in a manner acceptable to regulators
and post-mining land users.
In this document the term closure is based in the ANZMEC/MCA (2000) definition and includes
decommissioning and rehabilitation and culminates in tenement relinquishment.
The aim of this closure plan is to provide a strategic planning framework for the closure of
Aztec’s Iron Ore Project by:
•
Identifying those aspects relating to decommissioning and closure which may impact on the
environment, health and safety and developing management strategies to be implemented as
part of the project’s design and construction to minimise this impact;
•
Identifying closure costs to establish a financial provision;
•
Providing a basis for consultation with regulators and identified stakeholders regarding the
post-mining land uses of the project area and the development of agreed completion criteria;
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Koolan Island Iron Ore Mine and Port Facility
Conceptual Closure Plan
•
Identifying those aspects relating to closure that will require determination and/or input by
appropriate regulatory agencies relating to completion criteria and the relinquishment of
Aztec’s mineral leases on Koolan Island; and
•
Providing details of the management strategies to be implemented by Aztec to the
appropriate regulatory agencies as part of project approvals.
Throughout the life of the project the closure plan will be reviewed to consider changes in site
conditions, operations, technology and community expectations.
1.1
Previous Operations
William Dampier, in 1688, was the first European to discover the Buccaneer Archipelago. Early
pearling fleets frequently stopped at the islands of the Yampi Sound to pick up ballast from the
beaches and coves. It was eventually discovered that the ballast was in fact ironstone and the
earliest attempts to develop these reserves was in 1907 when the first leases were granted.
Eventually, after changing hands several times, the leases became the property of BHP.
Through the 1940s, mining companies moved in on the rich deposit, and by 1963, BHP had
established substantial mining operations on both Cockatoo and Koolan Islands. From 1965 to
1993, BHP extracted approximately 68 million tonnes of high-grade iron ore from five pits on
Koolan Island - Main, Mullet, Eastern, Barramundi and Acacia.
During mine operations BHP maintained infrastructure consisting of:
•
Haul roads and access roads;
•
Airstrip;
•
Accommodation village;
•
Workshops and bulk storage facilities;
•
Mobile plant;
•
Power Station;
•
Primary crushing and screening plant;
•
Shiploading and wharf facilities;
•
Bulk fuel storage facilities;
•
Administration offices; and
•
A series of water bores.
A layout of the mine infrastructure is illustrated in Figure 1.2.
As part of mining operations BHP reclaimed the area east of Arbitration Cove (Lower Mangrove
Inlet) with waste rock. Waste rock dumps were also placed around each of the pits.
BHP operated three domestic tips and four industrial tips on the island. There are no known
records of the materials that were placed in the tips, management techniques, or the longevity of
each waste disposal area.
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BHP closed the mine in 1993, which consisted of decommissioning and disassembly of all fixed
and mobile plant including the wharf facilities, some burial of infrastructure, rehabilitation of
cleared areas by moon scaping, and the construction of a channel to allow seawater flooding of
the Main pit. Apart from known domestic and industrial tips sites, the exact locations of other
burial pits, and the materials buried as part of decommissioning is unknown.
The footprint of BHP activities was contained within the southern part of the island with the
northern shore line and the western and north-eastern ends of the island remained undisturbed
(Figure 1.2).
1.2
Current Operations
Aztec commenced exploration drilling in February 2004 targeting the five ore bodies already
mined by BHP. To date, approval has been granted by DoIR and DoE for the clearing of 37.2 ha
(76.5 % in previously disturbed areas) for access roads, drill pads, minor landfill and an
exploration accommodation camp.
1.3
Planned Operations
Aztec is planning to commence production by the early 2007, at a mining rate of 2-4 million
tonnes of ore per annum with a strip ratio of 6:1. At this rate it is planned to have a mine life of
more than nine years (Table 1.1).
Although previously mined by BHP, there is no existing infrastructure on Koolan Island to
support a mining operation. As such, the scope of the Koolan Island Iron Ore project includes:
•
Construction and establishment of complete mine infrastructure;
•
Mining of three main ore bodies;
•
Dewatering of the main pit;
•
Partial infill of Arbitration cove for expansion of the main pit;
•
Waste rock management;
•
Primary crushing and dry screening of ore;
•
Stockpiling and Shiploading;
•
Construction of shiploading facility;
•
Maintenance of mine operations;
•
Maintenance of an accommodation village;
•
Management of environmental impacts;
•
Rehabilitation and Decommissioning; and
•
Relinquishment of mining tenements.
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1.4
Project Closure Plan Scope
This plan only covers Aztec mining lease areas disturbed by Aztec’s exploration and mining
operations, as shown in Figure 1.3. The Closure Plan excludes:
•
All areas outside Aztec’s current mining leases;
•
Areas within Aztec’s mining leases that have not been disturbed by Aztec’s operations;
and
•
The airstrip, located to the north of the mine area, which is used by the public.
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Table 1.1
Summary of Key Characteristics associated with the Proposal
Component
Key Aspect
Description
Mining
Location of Mine
Koolan Island – 130 km NW of Derby in the
Buccaneer Archipelago
3 main deposits: Main Pit, North Pit and East Pit
Main Pit: 17.4 Mt resource
Mullet Pit: 6.3 Mt resource
Eastern Pit: 5.4 Mt resource
Main Pit: Current 80m Final 165m below sea level
Mullet Pit: Current 50m Final 80 below ground level
Eastern Pit: Current 60m Final 115 m below ground
level
Generally > 100 m below ground level
High grade hematite (61-68%)
Commence construction early 2006
Commence production in early 2007
2 – 4 million tonne per year
(Year 1 – 2 Mt, Year 2 - 2.5 Mt, Year 3 – 8 - 4 Mt
and Year 9 - 0.6 Mt)
9 Years +
Ore Deposits
Depth of mine pits
Depth of water table
Ore Type
Proposed Project Schedule
Ore Mining Rate
Project Life Span
Approximate Year of
Decommissioning
Stockpile of ROM material
Waste Dump Capacity and Area
Strip Ratio (waste : ore)
Amount of land disturbance
Dewatering of
Main Pit
Construction of Sea Wall
Dewatering
Ore Processing
Primary Crushing and Screening
Ship loading
Ship loading
Infrastructure
Project access
Power Source
Water Source
Workshops
Equipment
Fuel Consumption
Ore Handling
Port Facility
Accommodation
General
Work force
Solid Waste
Bulk Transport of material
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2015
Capacity: 100,000 Tonne; Area: 10 ha
3
Capacity: 124 Mm ; Area: 280 ha
Approximated at 6:1
540 ha (45% previously disturbed)
300 m wall across Arbitration Cove, 75 m wide at
the base, 15 m high
Initial Dewatering: Approximately 7 Mm3 of sea
water at 300 l/s
Maintenance: Ongoing rate of 50-150 l/s
Turbid water will be placed in sedimentation pond
prior to discharge into ocean
2 stage dry crushing and screening plant to produce
fines and lump product.
Product will be stockpiled near the ship loader for
direct loading
Inter-island: Aircraft
Intra-island: Haul and access roads
Power : Diesel fuelled 2 MW power station
Generators: 5 x 0.5 kVa generators
Fresh water will be extracted from three existing
bores, 75 kL/day potable water
Heavy and light equipment maintenance workshops
Conventional heavy and light mobile equipment
Approx 10.6 ML/year
Ore will be transferred from the stockpiles to the
ship loader via a conveyor system
A ship loader and jetty will be re-established to
enable ship loading
Single persons village
200 persons, with fluctuations during peak periods;
fly in, fly out
Maximum of 300 tonnes per year
Via Barge from Derby / Broome, or coastal shipping
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Koolan Island Iron Ore Mine and Port Facility
Conceptual Closure Plan
Figure 1.1a
Figure 1.1b
Proposal Study Region.
Project Location (inset box – see Figure 1.1a).
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BHP mining operations at Arbitration Cove prior to 1993.
BHP ship loading wharf facilities at Arbitration Cove prior to 1993.
Recent photograph of Arbitration Cove taken in July 2004.
Figure 1.2
BHP Mining Operations at Arbitration Cove prior to 1993 (top four
photos) and a view of Arbitration Cove at present (July 2004).
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Figure 1.3
Proposed operations on Koolan Island.
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Conceptual Closure Plan
2.0
PROJECT CLOSURE OBJECTIVES
Planning for mine closure seeks to address the social, environmental, financial and safety aspects
of mine closure. The aim is to prevent or minimise long-term environmental impacts and to
create a self-sustaining natural ecosystem or alternate land use based on an agreed set of
objectives (ANZMEC/MCA, 2000). In undertaking mine closure activities at Koolan Island,
Aztec will fulfil the following objectives:
•
Protect public safety;
•
Minimise environmental and socio-economic impacts;
•
Meet legislative requirements;
•
Enable all stakeholders to have their interests considered during the mine closure
process;
•
Re-establish self-sustaining ecosystems compatible with post-mining land use
requirements;
•
Establish stable landforms that are sympathetic with the regional landforms and
geotechnically stable;
•
Develop completion criteria to enable relinquishment to occur;
•
Undertake monitoring until agreed completion criteria are achieved;
•
Fulfil commitments in the Closure Plan; and
•
Release the operator from further liability.
Decommissioning and rehabilitation will be undertaken progressively, where practicable,
throughout the life of the mine and will involve:
•
Determining appropriate post-mining land uses for disturbed areas;
•
Determining if any infrastructure such as the wharf and jetty can be utilised by another
party;
•
Removing or burying any infrastructure not to be utilised by another party;
•
Removal and treatment of contamination;
•
Establishing final landforms and drainage paths; and
•
Rehabilitating areas that have been disturbed by Aztecs operations.
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3.0
LEGAL OBLIGATIONS
To ensure the closure of Aztec’s Iron Ore Project meets all legal requirements a review was
undertaken to identify legislation and guidelines applicable to mine closure. As part of the
review of the Closure Plan during the project life, legislation and other requirements will be
reviewed to identify any new requirements.
3.1
Legislation
West Australian legislation as such does not specifically deal with or refer to mine closure.
However, Section 84 of the Mining Act 1978 does allow the Minister for Mines to impose mine
closure conditions at his/her discretion on mines administered under this Act.
The following legislation was deemed relevant to mine closure and have been taken into account
when developing this Conceptual Closure Plan.
•
Aboriginal Heritage Act, 1972
•
Conservation and Land Management Act, 1984
•
Contaminated Sites Act, 2003
•
Environment Protection and Biodiversity Act, 1999
•
Environmental Protection Act, 1986 part IV & V
•
Heritage of Western Australia Act, 1990
•
Mines Regulation Act, 1946
•
Mines Safety and Inspection Act, 1994
•
Mines Safety and Inspection Regulations, 1995
•
Mining Act, 1978
•
Rights in Water and Irrigation Act, 1914
•
Soil and Land Conservation Act, 1945
•
Waterways Conservation Act, 1976
•
Western Australia Marine Act, 1981
•
Wildlife Conservation Act, 1950
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3.2
Guidelines and Codes of Practise
The Guidelines and Codes of Practice outlined below were used in the preparation of this
document:
•
ANZMEC/MCA (2000), Strategic Framework for Mine Closure. Australian and New
Zealand Minerals and Energy Council and Minerals Council of Australia. Canberra,
ACT.
•
Australian Mining Industry Council (1989), Mine Rehabilitation Handbook.
•
Chamber of Minerals and Energy of Western Australia Inc (November 1999) Mine
Closure Guidelines for Minerals Operation in Western Australia.
•
Department of Environment (1996), Code of Practice for Country Landfills.
•
Department of Minerals and Energy (1997) Safety Bund Walls around abandoned Open
Pit Mines. Department of Mines & Energy, WA.
•
Department of Minerals and Energy (1998) Geotechnical Considerations in Open Pit
Mines Draft. Department of Mines & Energy, WA.
•
Department of Minerals and Energy (1996), Guidelines for Mining in Arid
Environments. Department of Mines & Energy, WA.
•
Minerals Council of Australia (February 2000) Code for Environmental Management.
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4.0
COMPLETION CRITERIA
Completion criteria are an agreed set of environmental indicators, which upon being met, will
demonstrate successful rehabilitation of a site and hence are inextricably linked to the
monitoring programme (ANZMEC/MCA, 2000). Rehabilitation can be considered successful
when the site can be managed for its designated land use without any greater management inputs
than other land in the area being used for a similar purpose (EPA, 1995).
4.1
•
4.2
Objective
To establish a set of indicators which will demonstrate the successful completion of the
closure process and facilitate the release of the mining operator from further
environmental obligations.
Proposed Completion Criteria
The project proposed completion criteria have been developed taking into consideration the
following factors:
•
Public health and safety;
•
Regulatory requirements;
•
Aztec’s Environmental Policy;
•
Geotechnical stability of final landforms;
•
Sustainability of revegetated areas;
•
Expectations of stakeholders; and
•
Post-closure land use objectives.
The proposed completion criteria, detailed more fully in Section 9 (Proposed Closure
Strategies), are summarised below:
•
Post-closure land use objectives have been established and agreed by the appropriate
regulatory agencies;
•
Mining-related infrastructure not required by a post-closure land user has been removed
or buried;
•
Contaminated areas have been remediated to levels that are acceptable to the DoE and
other stakeholders;
•
Post mining landforms are geotechnically stable and respond to erosion agents in a
similar manner to naturally occurring landforms composed of similar rock types;
•
Final landforms are compatible with the adjacent landscape;
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•
Runoff from surface waters within and running off the site have similar quality to runoff
from undisturbed sites;
•
Self-perpetuating and resilient locally native vegetative cover has been established on
disturbed areas;
•
The local marine environment displays similar floral, faunal and benthic habitat
diversity, health and water quality as other nearby marine ecosystems;
•
Identified aboriginal heritage sites have not been disturbed;
•
No new outbreaks of weeds or pest have occurred due to Aztec’s operations;
•
No adverse significant impacts to flora or fauna have occurred due to Aztec’s operations;
•
Relevant legislative requirements and ministerial commitments have been met;
•
Agreed monitoring programs are implemented;
•
As part of relinquishment all required records and reports have been submitted to the
appropriate regulatory agencies; and
•
There are no unsafe areas where the general public could gain inadvertent access.
Completion criteria should ultimately stem from consultation between the proponent and
stakeholders. This communication should be ongoing and open, providing for a mutually
agreeable set of criteria against which the success of the closure and rehabilitation program can
be measured. Aztec will consult with all stakeholders and interested parties throughout the life
of the project to develop agreed completion criteria.
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5.0
CONTAMINATED SITES
5.1
Objective
•
Develop a process with the DoE for the management of any areas identified as
contaminated by BHP’s previous activities; and
•
Undertake a contaminated site assessment as per the DoE guidelines prior to Aztec
commencing mining operations on Koolan Island, and again as part of the
decommissioning and closure process.
5.2
Contaminated Sites Investigation and Management
Under the Contaminated Sites Act 2003 a site is considered to be contaminated if it has a
substance present at above background concentrations that presents, or has the potential to
present, a risk of harm to human health, the environment or any environmental value.
Aztec was required by the DoE to identify potential environmental contamination issues
resulting from historic mining of Koolan Island, which through the proposed mining activities
could impact upon future mining and the environment. In response, Aztec commissioned URS
Australia Pty Ltd (URS) to conduct a Phase 1 and Phase 2 environmental site assessment in
November and December 2004 (URS, 2005). The Phase 2 investigations were a baseline study
to enable Aztec to understand the potential environmental liabilities associated with future
mining on Koolan Island.
The main potential contamination issues from former mining activities at Koolan Island are:
•
Domestic and industrial landfill disposals;
•
Workshop activities;
•
Fuel and waste oil distribution and storage;
•
Buried machinery; and
•
Former township support systems and infrastructure.
The investigations indicated that the primary potential sources of contamination present on
Koolan Island are petroleum hydrocarbons and asbestos. The proposed mining activities may be
undertaken in areas where potential contamination has been identified, such as petroleum
hydrocarbons in the Main Pit. Extensions to the Mullet Pit are not expected to result in an
environmental or human health based issue. Where Aztec disturbs areas of identified
contamination they will remediate these areas as per the DoE guidelines.
The potential exists for contamination to occur during the life of the project due to the handling
and storage of hydrocarbons and chemicals. This potential will be minimised by ensuring
hazardous materials, such as hydrocarbons and chemicals, are stored in contained areas and
spills are cleaned up immediately.
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A Contaminated Sites Assessment process will be undertaken as per the DoE Contaminated
Sites Guidelines, before decommissioning of infrastructure occurs and will incorporate the
following:
•
Investigation: determine the nature and extent of any soil and/or groundwater
contamination;
•
Assessment: evaluate the risks of any identified contamination to human health or the
environment;
•
Action Plan: develop and document an operations plan and implementation schedule
which addresses all necessary activities including disposal of contaminated material,
monitoring and criteria for completion;
•
Consultation: discuss all aspects of the program and obtain agreement from DoE (as the
responsible regulatory agency), together with other agencies as appropriate;
•
Implementation: undertake all aspects of the program in compliance with the
documented plan and any relevant standards such as AS 4482.1 – 1997 related to the
sampling and investigation of contaminated soils;
•
Validation: undertake monitoring and/or testing, using appropriate, recognised methods,
to demonstrate reduction of contamination to an acceptable levels using an independent
consultant; and
•
Closure: Obtain regulatory signoff that the remediation process has been effective and
the site is no longer contaminated.
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6.0
DECOMMISSIONING
6.1
Objective
•
Remove or dispose of infrastructure, not to be utilised by another party, associated with
Aztec’s iron ore project; and
•
Dispose all waste material appropriately.
6.2
Removal of Infrastructure
During the decommissioning phase of the project all infrastructure that cannot be used by
another party will be removed, including concrete footings, and the disturbed areas rehabilitated.
This could include the removal of:
•
Crushing and screening plant, and processing buildings;
•
Fuel and Bulk Storage Facilities and associated pipe work;
•
Workshops;
•
Ship loader (including conveyors, conveyor structures and on-shore and offshore
footings) and jetty (including deck, substructures, piles and dolphins);
•
Dewatering equipment;
•
Power Station;
•
Explosives magazine;
•
Offices and accommodation village; and
•
Support infrastructure such as water pipelines, redundant structures at the airstrip and
recreational facilities.
The dismantling of infrastructure will generate scrap and waste materials that will be disposed in
the following manner:
•
Steel will be stored until the mine is decommissioned and shipped off the island for
recycling;
•
Inert material that is not reusable (such as concrete, building rubble) will be buried in the
landfill site;
•
Hazardous materials, such as asbestos, will be disposed of in accordance with
appropriate governing regulations; and
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•
Left over fuel, oils and chemicals will be removed from site and returned to the supplier.
Waste oils, fuels and chemicals will be removed from site and disposed of at an
appropriate waste facility, recycled or reused where possible.
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7.0
DEVELOPMENT OF FINAL LANDFORMS
7.1
Objective
•
Post mining landforms are geotechnically stable and respond to erosion agents in a
similar manner to naturally occurring landforms composed of similar rock types;
•
Landforms are compatible with the adjacent landscape; and
•
Runoff from surface waters within and running off the site have similar quality to runoff
from undisturbed sites.
7.2
Shaping of Landforms
A major cause of serious erosion on newly created landforms is the lack of adequate drainage
control. It is essential to design and construct drainage control measures that will handle the
expected rainfall events (DME, 2001).
The DME recommends that sloped landforms be covered with topsoil and then deep ripped to a
minimum of 1 m on contour. It is essential that rip lines are surveyed to ensure that they are
horizontal for the entire length. Ripping on contour minimises the amount of water flow along
the line encouraging infiltration of water and minimise erosion.
To ensure final landforms are geotechnically stable, not prone to ersoion and able to be
successfully rehabiliated the DoIR recommends slopes of no greater than 20 ° with benches
every 7–10 m of vertical height. A slope of 20 ° is the maximum that machinery can safely
work on. However, soil characteristics, rainfall, drainage and topography are all contributing
factors that have to be taken into account in determining the optimal slope angle and slope
length.
Reshaping of landforms aims to produce slopes with angles, lengths and shapes compatible with
the surrounding landscape, suitable for the proposed land use and not prone to an unacceptable
rate of erosion. On finalisation of the project, the following landforms will require earth works
reshaping:
•
Waste Dumps;
•
Borrow Pits;
•
Haul roads; and
•
Seawall.
Due to the mining schedule, Aztec will only backfill pits where it is economic to do so.
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Reshaping of landforms will be undertaken to:
•
Prepare landforms and disturbed areas to acceptable standards prior to the
implementation of revegetation procedures;
•
Ensure post mining landforms are geotechnically stable and respond to erosion agents in
a similar manner to naturally occurring landforms composed of similar rock types;
•
Minimise long-term visual impact by creating landforms which are compatible with the
adjacent landscape;
•
Reinstate, where practicable, natural drainage patterns;
•
Ensure runoff from surface waters within and running off the site have similar quality to
runoff from undisturbed sites; and
•
Batter free-standing slopes to an angle of 20 º or less, or to slopes consistent with the
surrounding landforms.
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8.0
REHABILITATION STRATEGIES
8.1
Objectives
•
Where feasible areas disturbed by Aztec’s operation will be rehabilitated;
•
Species native to Koolan Island will only be used in the rehabilitation; and
•
Rehabilitation will be undertaken as soon as practicable to facilitate fauna habitat
restoration.
8.2
Rehabilitation
Climate is an important consideration in relation to revegetation procedures. Plant growth in the
Kimberley is closely tied to seasonal fluctuations; the majority of growth occurs in the wet
season as warm temperatures combined with moist soil conditions encourage proliferation of
plants. In certain instances plants will naturally recolonise areas of exposed soils, however,
these areas do not necessarily resemble natural ecosystems, comprising principally grasses and
herbs. In order to successfully bind the soil and facilitate development of permanent vegetation,
planting of shrubs and trees is required in addition to natural revegetation. The most suitable
time for seeding or planting is during the ‘build-up’ to the wet season, or following the first
substantial rains, as this allows for a period of several months during which plants can become
established prior to the dry season with its concomitant loss of soil moisture. This is particularly
the case for perennial species.
The use of topsoil as a growing medium is important for successful rehabilitation. During the
life of the mine any area to be disturbed will have the topsoil stripped and stockpiled, and
vegetation debris, logs and leaf litter will be retained for reuse during rehabilitation.
Rehabilitation will consist of:
•
Where available, topsoil will be utilised to provide a foundation into which native
vegetation will be planted and/or seeded. Topsoil will be applied at a minimum of 100
mm to:
• Accommodate root systems;
• Provide water holding capacity to attenuate moisture from rainfall and to sustain
vegetation through dry periods;
• Allow for long term erosive losses; and
• Prevent desiccation.
•
Vegetation debris, logs and leaf litter from the clearing of areas will be spread over
rehabilitated areas to provide fauna habitat;
•
Ripping on contour is required to relieve compaction and improve water infiltration.
Deep ripping to a depth of 1 m will be undertaken where the soil or waste material is of
low permeability. In areas where the soil or waste material is of high permeability
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cultivation on contour will be undertaken. On steep slopes this may require terracing or
benching. All ripping, terracing or benching will be surveyed to ensure that they are on
contour;
•
Direct seeding and/or planting will be undertaken to encourage vegetation growth to
stablilise surfaces and aid the integration of landforms into the surrounding landscape.
Seeding and/or planting will be undertaken prior to the wet season as soon as possible
after earthworks using seed and plants native to Koolan Island;
•
Where necessary, fertilizer will be applied to offset the loss of nutrients and soil
microbiota associated with loss of topsoil; and
•
Rehabilitation and closure procedures will include measures to address specific habitat
types of listed fauna.
8.3
Monitoring of Rehabilitation
•
Rehabilitation monitoring will be carried out until revegetation meets the designated
completion criteria and is signed off by the DoIR. In response to monitoring results,
infill planting and weed control will be implemented as necessary;
•
A visual inspection of rehabilitated areas will be carried out following rain to ensure that
any potential erosion issues are identified early and can be repaired before they become
severe;
•
Photographic monitoring will be undertaken. This will consist of establishing fixed
photographic points (adequately marked with a long lasting item such as metal star
picket) and taking photographs from each of these points, usually in four directions
(north, south, east and west);
•
Quantitative assessment of the progress of revegetation will be undertaken. Replicate
monitoring quadrats (20 m x 20 m) will be established and total plant species richness
and plant cover index will be recorded; and
•
Reporting procedures will be established to ensure that results of all trials and actions are
properly recorded, referenced, and available for other personnel and for long-term
reference.
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9.0
PROPOSED CLOSURE STRATEGIES
Before decommissioning occurs, a risk assessment will be undertaken to identify risk to
environment, health and safety. A document decommissioning strategy will be developed to
ensure that risks are managed to an acceptable level.
9.1
Mine Pits
Aztec intends to reopen and expand on the previously mined ore bodies to access remnant ore
reserves. All five previous mined pits will be reopened and amalgamated into three active pits.
They are the Main Pit (Main Pit), Mullet Pit (Mullet and Acacia Pits) and Eastern Pit (Eastern
and Barramundi Pits) (Figure 9.1).
The Main Pit will be expanded to the south by approximately 17 ha and extended on the east and
west ends by 22 ha. The Mullet Pit will amalgamate both Mullet and Acacia Pits, and will have
an estimated surface area of 55 ha.
The Eastern Pit will amalgamate Eastern and Barramundi Pits, with extensions of the pits
towards Ellis Fjord. The final formation will have a surface area of approximately 63 ha.
Where practicable and economically feasible the mining regime will be designed to include
backfilling of mined-out pits. The decision to flood the Main Pit on closure will be made at a
future date after consultation with relevant agencies including CALM and DoE approximately 2
years before closure. Prior to implementation of this plan the matter will be reviewed with all
relevant stakeholders in order to identify the most appropriate action.
9.1.1
Closure Objective
•
Ensure pit void and walls are structurally stable; and
•
Ensure public safety by restricting access to remaining pits.
9.1.2
Closure Strategy
Stability of Pit Walls
Geotechnical investigations will be undertaken to determine the optimum final landform of the
mine pit walls to ensure stability of the landform.
Safety Bunds
In order to minimise inadvertent public access to abandoned open pits:
•
An abandonment bund wall will be constructed around the perimeter of open pit voids
greater than 5 m in depth;
•
The bund wall will be constructed outside the area designated as being susceptible to
wall collapse; and
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•
The location and design of the abandonment bund will be in accordance with procedures
detailed in “Safety Bund Walls around Abandoned Open Pit Mines” (DME, 1997).
Rehabilitation
There is evidence of natural revegetation on some areas of the pit walls, including growth of
trees and shrubs, which indicates that plant regrowth is possible. On completion of mining, final
rehabilitation of the pit walls around the active mining area will be undertaken.
•
Where required, additional earthworks will be undertaken on those areas of the pit walls
that are safely accessible to improve long term structural stability and facilitate
revegetation; and
•
Hand seeding will be undertaken where access is available to improve long term
stability, particularly in the erosion prone haematite-poor grey band material.
9.1.3
Completion Criteria
•
Pit voids and walls are assessed by a suitably qualified engineer and determined to be
structurally stable; and
•
Safety bunds comply with the procedures detailed in “Safety Bund Walls around
Abandoned Open Pit Mines” (DME, 1997).
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Figure 9.1
Layout of Koolan Island.
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9.2
Seawall
To facilitate the expansion and reactivation of the Main Pit, and to maintain dry working
conditions a seawall extending approximately 300 m across the mouth of Arbitration Cove will
need to be constructed. It will be keyed through existing waste dumps on the abutments and into
sound bedrock, where it intersects the margin of the cove.
The seawall will reach an approximate height of 15 m to minimise overtopping and damage to
the sea wall during storm events. The width of the sea wall at foundation level will be
approximately 75 m, with an upstream slope of 1(v):2.5(h) and downstream slope of 1(v):2(h).
At its crest the width of the sea wall will be 10 m.
9.2.1
•
9.2.2
•
9.2.3
•
9.3
Closure Objective
At the time of writing this Closure Plan it is intended that the seawall will be breached to
reinstate the natural tidal movement of the area. The topic will be reviewed prior to
implementation of the plan.
Closure Strategy
The breaching of the seawall will be designed to minimise the impact to coastal habitats
and allow for re-establishment of marine biota on disturbed areas.
Completion Criteria
Marine biota have re-established in the area of the seawall to a similar density and
diversity as that existing prior to construction of the seawall.
Waste Rock Management
Overburden materials comprising low grade ore and un-mineralised rock will be generated as
part of the mining process. Due to the geology of the area, ore and waste rock materials consist
predominantly of sandstone and conglomerates, and do not pose physiochemical impacts to the
environment, hence there are no acid rock drainage issues.
Waste rock will be disposed in waste dumps located adjacent to the existing pits or within
extensions of previously disturbed areas (Figure 9.1).
Four main areas have been delineated for waste rock placement:
•
Main Dump (west): The existing waste dumps to the northwest of the Main Pit run into a
series of gullies that drain to the north of the island. It has a capacity of 41.3 Mm3;
•
Mullet Dump: The area between the Main Pit and North Pit has been previously
disturbed to accommodate waste dumps and low grade stockpiles. The road from the
Main Pit to the North Satellite Pit runs along a ridge between two gullies that are
enclosed by either existing pits or waste dumps. It has a capacity of 2.9 Mm3 of waste
rock;
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•
Eastern Dump: The largest of the dumps is East Dump B to the north of the East Pit. It
has a capacity of 40.9 Mm3 and is the extension of two dumps created during previous
mining activities and the backfilling of two gullies to 150 m ASL; and
•
Main Dump (east): The dump to the south of the East Pit includes access roads to the
crushing and stockpiling areas. These new access roads are required as the East Pit and
pushback for the Main Pit are likely to remove existing access. This dump has a capacity
of 15.7 Mm3, fills a number of small gullies to 160 m ASL and partially buries an
existing waste dump.
All waste dumps will be designed to a flat crest and will be no higher than the general terrain.
The area on top of the dump will be designed to accommodate additional waste material to
create long term landform slopes. Sedimentation ponds will be established downstream of waste
dumps to collect run off from the slopes during waste dump construction, and allow sediment
fall out / evaporation.
Low grade material will be stored separately to waste rock to enable possible reclaiming for
processing at a later stage of the mine life. These materials will be preferentially stored nearest
to the ROM crusher for ease of access.
The area of disturbance caused by the conceptual waste dumps is 281 ha of which a large
proportion was previously disturbed and rehabilitated (31.6 %). Specific waste dump locations
for each pit will be determined as part of feasibility studies.
Waste dumps are often the most visible landforms remaining following open pit mining. Control
of erosion on waste dump slopes is also an important consideration.
During the engineering phase of the proposal, investigations will be conducted into the volume
of saline waste rock material that will be produced, the appropriate placement of the waste rock
and the type of contamination and methods required to prevent contamination of groundwater
9.3.1
Closure Objective
•
To ensure that the profile of the waste rock dump final structure is safe, stable, blends
into the surrounding landscape and not prone to erosion;
•
The waste rock and slope gradients will be capable of withstanding the intense rainfall
events of the wet season; and
•
To ensure sufficient cover of vegetation will be established to minimise erosion
resulting from the impact of severe rains on dry soils.
9.3.2
Closure Strategy
Waste dumps will require extensive earthworks and subsequent seeding and revegetation to
ensure they are stable and blend into the surrounding landscape.
•
Waste dumps will be designed to ensure that the profile of the final structure is safe,
stable and not prone to erosion;
•
Dumps will be designed so after rehabilitation they blend into the surrounding
landscape;
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•
Adequate drainage control will be implemented to ensure that erosion does not occur;
•
Outslopes will be designed at less than 20o as required for geotechnical stability, or will
be consistent with surrounding landforms;
•
A major cause of erosion on newly created landforms is the lack of adequate drainage
control. Drainage control measures will be designed and constructed to handle
expected rainfall of the area;
•
Dump surface will be covered with clean fill and if available soil to a minimum depth
of 100 mm;
•
Both the tops and the side of the waste dump will be contour ripped to encourage
infiltration of rainfall; and
•
9.3.3
Waste dumps will be seeded or planted with local species.
Completion Criteria
•
Waste dump slopes are below 20 o;
•
Waste dumps are assessed by a suitably qualified engineer and determined to be
structurally stable;
•
Rehabilitated waste dumps respond to erosion agents in a similar manner to naturally
occurring landforms composed of similar rock types; and
•
Vegetation cover is self-sustaining.
9.4
Borrow Pits
9.4.1
Objectives
•
To ensure the profile of borrow pits final structure is safe, stable, blends into the
surrounding landscape and not prone to erosion; and
•
A sufficient cover of vegetation is established to minimise erosion resulting from the
impact of severe rains on dry soils.
9.4.2
Closure Strategy
Borrow pits will be progressively rehabilitated as soon as possible following pit closure. The
sides of the pits will be battered to a maximum slope of 20 o. If required, diversion drains and
upslope windrows, will be utilised to divert surface water flow from entering the pit causing
ponding and erosion. Pits will be rehabilitated as per the strategy detailed in Section 8.
9.4.3
•
Completion Criteria
Borrow pit slopes are below 20 o;
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•
Borrow pits are assessed by a suitably qualified engineer and determined to be
structurally stable;
•
Once rehabilitated borrow pits respond to erosion agents in a similar manner to naturally
occurring landforms composed of similar rock types; and
•
Vegetation cover is self-sustaining.
9.5
Dewatering
The Main Pit will require dewatering in two stages; initial bulk displacement of sea water, and
ongoing dewatering to maintain dry work conditions in the pit floor. Ongoing dewatering will
largely result from dewatering bores combined with some pumping from in pit sumps.
Infrastructure required for initial dewatering of sea-water will consist of:
•
Offshore dewatering discharge poly pipe(s) installed below the annual low water mark,
anchored and floated to facilitate discharge of water;
•
Poly pipe rising mains installed up the side of the pit wall;
•
Floating pontoons with suspended electric submersible pumps;
•
Centrally located and secondarily contained diesel powered generators to provide power
to the pumps;
•
Booster stations will be available to provide extra power as pressure head increases with
decrease in pit water level; and
•
A settling dam established adjacent to the Main Pit. When the water level of the Main Pit
is such that turbidity is being generated from pit floor disturbance, the water will be
directed to the settling dam prior to discharge into the ocean.
It is not anticipated that dewatering of the other pits will be required.
9.5.1
Objectives
•
All infrastructure associated with dewatering is removed; and
•
Impact on the marine environment from dewatering operations is minimised.
9.5.2
Closure Strategy
All infrastructure associated with dewatering will be removed and disposed of as per Section 4.
9.5.3
Completion Criteria
•
All infrastructure removed and disposed of appropriately; and
•
Monitoring of marine environment within Arbitration Cove shows no significant impacts
when compared to baseline study data.
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9.6
Haul Roads, ROM Pad, Stockpile and Ore Processing
Ore and waste rock will be transported by haul trucks to designated areas via haul roads.
Ore will be deposited onto ROM pads and fed into a crusher hopper by front end loaders. A flat
area, previously a waste dump at the base of the proposed access road is a potential area for the
ROM pad and stockpile. Initial designs suggest sufficient room exists for 500,000 tonne ROM
stockpiles.
A two stage dry crushing and screening plant and stacker will be installed east of the Main Pit to
produce 2-3 Mtpa of a predominantly fines product. Pre and post processing ore stockpiles will
be established on existing flat ground.
It is anticipated that shipping requirements will dictate the size of product stockpiles with a
nominal 250 kt stockpile for the fines product and 100 kt stockpile for a potential lump product
being available at the commencement of ship-loading. Product will be stockpiled in 8 – 10 m
high stockpiles. At this height, the area available in the stockpile yard has an approximate
holding capacity of 100,000 m3 of product.
The total area available to be disturbed to accommodate the pre and post crusher stockpiles
along with the ore handling plant and associated workshops, offices and infrastructure is 25 ha.
9.6.1
Objective
•
All infrastructure associated with haulage and ROM ore storage is removed; and
•
Disturbed areas are reshaped to blend into the landscape, and rehabilitated.
9.6.2
Closure Strategy
All infrastructure associated with ore processing will be removed as per Section 6.
Haul roads, ROM pad and stockpile and other disturbed area will be reshaped to ensure they
blend into the surrounding landscape and to control rainfall run-off. Areas will then be
rehabilitated as per Section 8.
9.6.3
Completion Criteria
•
All infrastructure removed and disposed of appropriately;
•
Once rehabilitated disturbed areas associated with ore processing respond to erosion
agents in a similar manner to naturally occurring landforms composed of similar rock
types; and
•
Vegetation cover is self-sustaining.
9.7
Jetty and Ship Loader
Steel fabricated jetty supported by steel piles driven into or anchored on the sea floor. A
travelling ship loader will run on rails along the jetty.
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9.7.1
Objective
•
If not required by another party, all infrastructure associated with ship loading will be
removed;
•
Disturbed areas are reshaped to blend into the landscape and rehabilitated; and
•
Disturbed marine areas recolonised by marine flora and fauna.
9.7.2
Closure Strategy
All infrastructure associated with the jetty and ship loader, including any structures in the ocean
will be removed as per Section 6, if not required by another party.
Disturbed areas will be reshaped to ensure they blend into the surrounding landscape and to
control rainfall run-off. Areas will then be rehabilitated as per Section 8.
Marine areas will be left to naturally recolonise.
9.7.3
Completion Criteria
•
All infrastructure removed and disposed of appropriately;
•
Rehabilitated areas associated with ship loader respond to erosion agents in a similar
manner to naturally occurring landforms composed of similar rock types;
•
Vegetation cover is self-sustaining; and
•
Marine biota have re-established in the area of the ship loader to a similar density and
diversity as that existed prior to construction.
9.8
Power Station
A 2 MW diesel fuelled power station will be established near the crushing plant to supply
electricity to the ore processing plant and shiploading facility. The power station will consist of
four to six, 0.5 kVA gensets.
9.8.1
Objective
•
All infrastructure associated with the power station is removed;
•
The area is investigated to determine if any contamination is present and if so
remediation strategies are developed and agreed with the DoE; and
•
Disturbed areas are reshaped to blend into the landscape and rehabilitated.
9.8.2
Closure Strategy
All infrastructure associated with the power station will be removed as per Section 6. Once the
infrastructure is removed a contaminated site assessment will be undertaken. If soil or water
contamination is identified a remediation plan will be developed and agreed with the DoE.
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Disturbed areas will be reshaped to ensure they blend into the surrounding landscape and to
control rainfall run-off. Areas will then be rehabilitated as per Section 8.
9.8.3
Completion Criteria
•
All infrastructure removed and disposed of appropriately;
•
Area not classed as a ‘contaminated site’ as per the Contaminated Sites Act 2003; and
•
Vegetation cover is self-sustaining.
9.9
Fuel and Bulk Storage Facilities
Distillate will be required for heavy and light vehicle use and for power generation. Fuel storage
facilities will be located at the Mobile Plant Workshop and Ore Processing Plant. A bulk
storage facility adjacent to the workshop area will be established for the contained storage of
hydrocarbons and chemical materials. To prevent contamination of ground and water from the
storage of fuel, hydrocarbons and chemical the Fuel and Bulk Storage Facilities will be fully
contained and designed and maintained according to statutory standards.
9.9.1
Objective
•
All infrastructure associated with fuel and bulk storage facilities is removed;
•
Storage areas are investigated to determine if any contamination is present and if so
remediation strategies are developed and agreed with the DoE; and
•
Disturbed areas are reshaped to blend into the landscape and rehabilitated.
9.9.2
Closure Strategy
All infrastructure associated with fuel and bulk storage facilities will be removed as per Section
6. Once the infrastructure is removed a contaminated site assessment will be undertaken. If soil
or water contamination is identified a remediation plan will be developed and agreed with the
DoE.
Disturbed areas will be reshaped to ensure they blend into the surrounding landscape and to
control rainfall run-off. Areas will then be rehabilitated as per Section 8.
9.9.3
Completion Criteria
•
All infrastructure removed and disposed of appropriately;
•
Storage areas not classed as a ‘contaminated site’ as per the Contaminated Sites Act
2003; and
•
Vegetation cover is self-sustaining.
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9.10
Workshops
Workshop facilities will be established for the repair and maintenance of mine equipment.
These facilities will include:
•
Haul truck and mining equipment maintenance bays;
•
Light vehicle workshop;
•
Lubrication area;
•
Welding and boiler making area;
•
Wash-down bays;
•
Tyre store; and
•
Offices.
To prevent the contamination of ground and water from the use and storage of oils and
chemicals workshop catchment areas will be contained and kept separate from storm water
interaction. Waste water from the workshop area will be treated by an oily waste water
separator unit prior to reuse for dust suppression, or licensed and monitored discharged into the
environment.
9.10.1 Objective
•
All infrastructure associated with the workshops is removed;
•
Workshop areas and the wash-down bay are investigated to determine if any
contamination is present and if so remediation strategies are developed and agreed with
the DoE; and
•
Disturbed areas are reshaped to blend into the landscape and manage drainage and
rehabilitated.
9.10.2 Closure Strategy
All infrastructure associated with workshops will be removed as per Section 6. Once the
infrastructure is removed a contaminated site assessment will be undertaken. If soil or water
contamination is identified a remediation plan will be developed and agreed with the DoE.
Disturbed areas will be reshaped to ensure they blend into the surrounding landscape and to
control rainfall run-off. Areas will then be rehabilitated as per Section 8.
9.10.3 Completion Criteria
•
All infrastructure removed and disposed of appropriately;
•
Workshop areas and the wash-down bay are not classed as a ‘contaminated site’ as per
the DoE the Contaminated Sites Act 2003; and
•
Vegetation cover is self-sustaining.
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9.11
Explosive Storage
Explosive magazines will be required for the storage of both wet and dry condition explosives,
component ingredients, and the initiation systems. Magazines will be licensed and contained to
ensure there is no contamination of ground or water due to the storage of explosives.
9.11.1 Objective
•
All infrastructure associated with explosives storage is removed;
•
Explosive storage areas are investigated to determine if any contamination is present and
if so remediation strategies are developed and agreed with the DoE; and
•
Disturbed areas are reshaped to blend into the landscape and manage drainage and
rehabilitated.
9.11.2 Closure Strategy
All infrastructure associated with explosive storage will be removed as per Section 6. Once the
infrastructure is removed a contaminated site assessment will be undertaken. If soil or water
contamination is identified a remediation plan will be developed and agreed with the DoE.
Disturbed areas will be reshaped to ensure they blend into the surrounding landscape and to
control rainfall run-off. Areas will then be rehabilitated as per Section 8.
9.11.3 Completion Criteria
•
All infrastructure removed and disposed of appropriately;
•
Explosive storage areas are not classed as a ‘contaminated site’ as per the Contaminated
Sites Act 2003; and
•
Vegetation cover is self-sustaining.
9.12
Landfill
A minor rural landfill will be established to manage the disposal of putrescible and inert wastes.
The landfill will be located in an area that poses minimal impact on surface and ground water,
and to reduce the potential for pollution. The location will be determined during feasibility
studies.
While in operation the following will be undertaken to ensure the landfill site impacts are
managed:
•
Only inert, general and putrescible waste will be disposed of in the landfill.
hazardous material will be disposed of according to government guidelines;
•
The landfill will be sited and designed to prevent surface water from draining into the
landfill. Diversion drainage structures will be used to divert stormwater flows away
from the landfill area;
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•
Surface water and groundwater monitoring will be undertaken if deemed to be necessary
to determine any impacts to water quality. If changes in water quality are identified the
DoE will be notified and an action plan developed;
•
Adequate separation distance will be maintained between the base of the landfill and the
water table. The DoE Code of Practice for Country Landfills (DoE, 1996) recommends a
minimum separation distance from the base of the landfill to the highest seasonal
groundwater level is 2 m for clay soils and 3 m for sandy soils; and
•
To facilitate consolidation of the landfill to minimise subsidence, waste material will be
compacted in layers not exceeding 500 mm thickness. Each time waste is disposed into
the landfill it will be covered by a depth of soil no less than 230 mm and compacted. Not
only will this facilitate consolidation of the waste material but ensure other impacts such
as fire, pests and odour are minimised.
9.12.1 Objective
•
All infrastructure associated with the landfill is removed;
•
The site is compacted and stable;
•
Landfill site is investigated to determine if any contamination of soil and groundwater
present and if so remediation strategies are developed and agreed with the DoE;
•
Landfill site is capped by a cover of low permeable material to a depth of 300 mm; and
•
Landfill area is reshaped to blend into the landscape and manage drainage and
rehabilitated.
9.12.2 Closure Strategy
The main issues associated with the closure of the landfill site area are;
•
Ground or surface water contamination due to the release of leachate from the site; and
•
Stability of the landfill area as subsidence occurs.
All infrastructure associated with landfill site will be removed as per Section 6. Once the
infrastructure is removed a contaminated site assessment will be undertaken. If soil or water
contamination is identified a remediation plan will be developed and agreed with the DoE. DoE
Karratha has advised that there is not a requirement to undertake testing for landfill gases.
Disturbed areas will be reshaped to ensure they blend into the surrounding landscape and to
control rainfall run-off. Areas will then be rehabilitated as per Section 8.
9.12.3 Completion Criteria
•
All infrastructure removed and disposed of appropriately;
•
Landfill area is not classed as a ‘contaminated site’ as per the DoE the Contaminated
Sites Act 2003;
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•
Landfill area is assessed by a suitably qualified engineer and determined to be
structurally stable;
•
Landfill site is capped by a cover of low permeable material to a depth of 300 mm; and
•
Vegetation cover is self-sustaining.
9.13
Bioremediation Facility
If required a small licensed bioremediation facility will be established for the management of
contaminated soil and biodegradable absorbent materials (peat and paper). The facility will be
constructed and managed as per the DoE guideline Bioremediation of Hydrocarbon
Contaminated Soils in Western Australia (2004). The facility will be located in an area that
poses minimal impact on surface and ground water, and to reduce the potential for pollution.
It will be constructed with a base layer of impermeable clay materials, and maintained in
accordance with license conditions.
9.13.1 Objectives
•
All infrastructure associated with the Bioremediation Facility is removed;
•
Bioremediation Facility is investigated to determine if any contamination of soil, and if
required groundwater, is present and if so remediation strategies are developed and
agreed with the DoE; and
•
Disturbed areas are reshaped to blend into the landscape and rehabilitated.
9.13.2 Closure Strategy
Closure of the bioremediation landfarm will not be undertaken until all areas where
contamination may occur have been investigated and remediated to agreed levels with the DoE.
On completion of bioremediation, the remediated soil will be removed and utilised in
rehabilitation of disturbed areas. Sampling of the natural ground surface beneath the
bioremediation facility will be undertaken to determine if any contamination is present.
Groundwater monitoring may be required if impacted material has leached into underlying soils
and the potential exists for groundwater contamination.
Once the bioremediation landfarm area has been investigated and any contamination remediated,
infrastructure associated with the bioremediation landfarm will be removed as per Section 6 and
the area reshaped to ensure they blend into the surrounding landscape and to control rainfall runoff. Areas will then be rehabilitated as per Section 8.
9.13.3 Completion Criteria
•
All infrastructure removed and disposed of appropriately;
•
Bioremediation Facility area is not classed as a ‘contaminated site’ as per the
Contaminated Sites Act 2003; and
•
Vegetation cover is self-sustaining.
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9.14
Accommodation
The accommodation village will be a nominally 200 person facility located at the site of the
previous town in the north east of the island, and will include the following facilities:
•
Single person en-suite rooms;
•
Laundry modules;
•
Kitchen and dry mess;
•
Administration office;
•
First aid facility;
•
Wet mess; and
•
TV room.
Sewerage and grey water management facilities will be as approved by the Shire of Derby and
West Kimberly, and will comprise of a series of leach drains.
9.14.1 Objectives
•
If not required by another party, all infrastructure associated with the accommodation
facility will be removed;
•
Areas were sewerage and grey water were managed will be investigated to determine if
any contamination of soil and if required groundwater, is present and if so remediation
strategies are developed and agreed with the DoE; and
•
Disturbed areas are reshaped to blend into the landscape and manage drainage and
rehabilitated.
9.14.2 Closure Strategy
All infrastructure associated with accommodation facility will be removed as per Section 6, if
not required by another party. Once the infrastructure is removed a contaminated site
assessment in the areas where sewerage and grey water were managed will be undertaken. If
soil or water contamination is identified a remediation plan will be developed and agreed with
the DoE.
Disturbed areas will be reshaped to ensure they blend into the surrounding landscape and to
control rainfall run-off. Areas will then be rehabilitated as per Section 8.
9.14.3 Completion Criteria
•
All infrastructure removed and disposed of appropriately;
•
Accommodation area is not classed as a ‘contaminated site’ as per the Contaminated
Sites Act 2003; and
•
Vegetation cover is self-sustaining.
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9.15
Administration Offices
Administration offices will be established at each of the main work areas. Offices will comprise
of office work space, ablutions, tea rooms and other general office facilities. Sewerage and grey
water management facilities will be as approved by the Shire of Derby and West Kimberly, and
will comprise of a series of leach drains.
9.15.1 Objective
•
If not required by another party, all infrastructure associated with the administration
offices will be removed; and
•
Disturbed areas are reshaped to blend into the landscape and manage drainage and
rehabilitated.
9.15.2 Closure Strategy
All infrastructure associated with administration offices will be removed as per Section 6, if not
required by another party. There will be no storage or use of chemicals within the office areas
and hence the site will not need to be investigated for contamination.
Disturbed areas will be reshaped to ensure they blend into the surrounding landscape and to
control rainfall run-off. Areas will then be rehabilitated as per Section 8.
9.15.3 Completion Criteria
•
All infrastructure removed and disposed of appropriately; and
•
Vegetation cover is self-sustaining.
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10.0 PUBLIC ACCESS AND SAFETY ASPECTS
10.1
Objectives
•
To ensure that disturbed areas are left stable and free of infrastructure and waste; and
•
To restrict access to areas that cannot be made safe through rehabilitative techniques.
10.2
Strategy
Public access and safety is an important issue at any mine site, particularly where there are
potential safety issues in the form of open pits and steep cliff faces. Though there are no public
facilities on Koolan Island. The public can assess the island by boat. Aztec considers it
essential that public access to the old mining areas is restricted and the sites rendered as safe as
possible.
The following measures will be implemented:
•
Signs clearly stating the risk to public safety and prohibiting unauthorised public access
will be erected around the site, particularly in areas near open pits;
•
On cessation of mining all roads leading to open pits will be closed; and
•
Safety bunds will be constructed to minimise the potential risk to the public safety of
inadvertent access to abandoned open pits as per the DoIR procedures detailed in “Safety
Bund Walls around Abandoned Open Pit Mines” (DoIR, 1997).
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11.0 RECORDS MANAGEMENT AND REPORTING SCHEDULES
11.1
•
11.2
Objective
To provide clear, detailed and comprehensive information on all aspects of the mines
operating and closure history.
Strategy
The retention of mine records is important because they provide:
•
A history of past developments;
•
Information for incorporation into state and national natural resource data bases; and
•
The potential to improve future land use planning and/or site redevelopment
(ANZMEC/MCA, 2000).
The following measures are proposed or ongoing:
•
Records of the history of the site following closure will be preserved to facilitate future
land use planning;
•
Reporting procedures will be established to ensure that results of all trials and actions
including remediation works and monitoring of revegetation are properly recorded,
referenced, and available for other personnel and for long-term reference;
•
Prior to relinquishment or surrender of tenure, records of the site development will be
submitted to the Responsible Authority; and
•
The types of records required by the Responsible Authority will include the following:
•
Geological records, including drilling data;
•
Plans and surveys of surface facilities;
•
Mining and production records;
•
Locations, quantities and qualities of waste dumps;,
•
Location, quantities and types of waste disposed in the landfill;
•
Engineering reports regarding the stability of final landforms;
•
Site specific surveys or studies; and
•
Mine Closure Plan.
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12.0 MONITORING
12.1
•
•
12.2
Objectives
To provide feedback on:
•
Final landform stability;
•
Marine environment recolonisation and water quality;
•
Surface and groundwater quality;
•
Public safety issues;
•
Rehabilitation and revegetation programs; and
To identify potential and actual impacts in order that remedial work can be implemented.
Strategy
The implementation of a monitoring programme is crucial in recording the success or otherwise
of the completion criteria, as well as validating agreed criteria for relinquishment (Chamber of
Minerals and Energy, 1999). Monitoring will address the following areas:
•
Biological (flora and fauna);
•
Marine environment;
•
Surface and groundwater;
•
Public safety; and
•
Landform stability.
Post-closure monitoring programs will be developed in consultation with appropriate regulatory
agencies. Suggested monitoring programs are:
•
Annual assessment of rehabilitated areas to monitor the re-establishment of vegetation on
all areas disturbed by mining activities i.e. waste dumps, stockpiles, infrastructure area,
haul and access roads etc.;
•
Annual assessment of surface and groundwater quality to ensure water quality in
disturbed areas is similar to that in undisturbed areas;
•
Once off assessment of the stability of final landforms by a suitable qualified engineer.
Monitoring will then be undertaken as per the stability assessment recommendations;
•
Annual assessment of rehabilitated coastal habitats to monitor the re-establishment of
marine biota and water quality in areas disturbed by the seawall and ship loader;
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•
Assessment of identified aboriginal heritage site on closure of the site to ensure they
have not been disturbed;
•
Assessment of weeds and pests on closure of the site to identify if any new outbreaks
have occurred due to Aztec’s operations;
•
Assessment of flora and fauna on closure of the site to identify if any impacts have
occurred due to Aztec’s operations; and
•
Monitoring of all safety bunds, fencing and signage on an annual basis to ensure all
public safety aspects are adequately addressed.
Monitoring will identify the need for remedial work at an early stage. Monitoring plans will be
developed in consultation with the appropriate regulatory agency and will include agreed actions
should monitoring identify issues that could lead to agreed completion criteria not being met.
Monitoring will be undertaken by Aztec until the agreed completion criteria have been met.
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14.0 SUMMARY OF MANAGEMENT ACTIONS
Table 14.1
Summary of Management Actions
Aspect
Consultation
Legal Obligations
Completion Criteria
Contaminated Sites
Management Actions
Relevant
Section(s)
Enable all stakeholders to have their interests
considered during the mine closure process
The aim of the closure plan is to provide a strategic framework for the closure of Aztec’s Iron Ore Project by providing
a basis for consultation with regulators and identified stakeholders regarding the post-mining land uses of the project
area and the development of agreed completion criteria.
1.0
Ensure that the closure of Aztec’s Iron Ore Project
meets all legal.
As part of the review of the Mine Closure Plan during the project life legislation and other requirements will be
reviewed to identify any new requirements.
Establish a set of indicators which will demonstrate the
successful completion of the closure process and
facilitate the release of the mining operator from further
environmental obligations
Aztec will consult with all stakeholders and interested parties throughout the life of the project to develop agreed
completion criteria.
A process is developed with the DoE for the
management of any areas identified as contaminated by
BHP’s previous activities.
To ensure that the site is not classed as contaminated due to Aztec’s operation, investigations will be undertaken as part
of the closure to determine whether contamination exists. A Contaminated Sites Assessment process will be undertaken
as per the DoE Contaminated Sites Guidelines which incorporates the following:
No areas disturbed by Aztec to be classed as a
contaminated site as per the Contaminated Sites Act
2003.
•
Investigation: determine the nature and extent of any soil and/or groundwater contamination;
•
Assessment: evaluate the risks of any identified contamination to human health or the environment;
•
Action Plan: develop and document an operations plan and implementation schedule which addresses all
necessary activities including disposal of contaminated material, monitoring and criteria for completion;
•
Consultation: discuss all aspects of the program and obtain agreement from DEP (as the responsible regulatory
agency), together with other agencies as appropriate;
•
Implementation: undertake all aspects of the program in compliance with the documented plan and any relevant
standards such as AS 4482.1 – 1997 related to the sampling and investigation of contaminated soils;
•
Validation: undertake monitoring and/or testing, using appropriate, recognised methods, to demonstrate reduction
of contamination to an acceptable levels using an independent consultant; and
•
Closure: Obtain regulatory signoff that the remediation process has been effective and the site is no longer
contaminated.
Objective(s)
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3.0
4.0
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Aspect
Decommissioning
Development of Final
Landforms
Objective(s)
Remove or dispose of infrastructure associated with
Aztec’s Iron Ore Project; and
During the decommissioning phase of the project all infrastructure that cannot be used by another land user will be
removed, including concrete footings, and the disturbed areas rehabilitated.
Dispose of waste material appropriately.
The dismantling of infrastructure will generate scrap and waste materials that will be disposed in the following manner:
•
Steel will be stored until the mine is decommissioned and shipped off the island for recycling;
•
Inert material that is not reusable (such as concrete, building rubble) will be buried in the landfill site;
•
Hazardous materials, such as asbestos, will be removed from the island and disposed of in accordance with
appropriate governing regulations; and
•
Left over fuel, oils and chemicals will be removed from site and returned to the supplier. Waste oils, fuels and
chemical will be removed from site and disposed of at a appropriate waste facility or reused where possible.
Post mining landforms are geotechnically stable and
respond to erosion agents in a similar manner to
naturally occurring landforms composed of similar rock
types.
Reshaping of landforms will be undertaken to:
•
Prepare landforms and disturbed areas to acceptable standards prior to the implementation of revegetation
procedures;
Landforms are compatible with the adjacent landscape.
•
Ensure post mining landforms are geotechnically stable and respond to erosion agents in a similar manner to
naturally occurring landforms composed of similar rock types;
•
Minimise long-term visual impact by creating landforms which are compatible with the adjacent landscape;
•
Reinstate, where practicable, natural drainage patterns;
•
Ensure runoff from surface waters within and running off the site have similar quality to runoff from undisturbed
sites; and
•
Batter free-standing slopes to an angle of 20 º or less, or to slopes consistent with surrounding landforms.
Runoff from surface waters within and running off the
site have similar quality to runoff from undisturbed
sites.
Rehabilitation
Management Actions
All area disturbed by Aztec’s operation will be
rehabilitated.
Relevant
Section(s)
6.0
7.0
Rehabilitation will consist of:
•
Where available, topsoil will be utilised to provide a foundation into which native vegetation will be planted
and/or seeded. Topsoil will be applied at a minimum of 100mm;
•
Vegetation debris, logs and leaf litter from the clearing of areas will be spread over rehabilitated areas to provide
fauna habitat;
•
Ripping on contour is required to relieve compaction and improve water infiltration. Deep ripping to a depth of
Species native to Koolan Island will only be used in the
rehabilitation.
8.0
Rehabilitation will be undertaken as soon as practicable
to facilitate fauna habitat restoration.
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Aspect
Objective(s)
Management Actions
Relevant
Section(s)
1m will be undertaken where the soil or waste material is of low permeability. In areas where the soil or waste
material is of high permeability cultivation on contour will be undertaken. On steep slopes this may require
terracing or benching. All ripping, terracing or benching will be surveyed to ensure that they are on contour;
Mine Pits
Ensure the pit void and walls are structurally stable.
Ensure public safety by restricting access to the
remaining pit
•
Direct seeding and/or planting will be undertaken to encourage vegetation growth to stabilise surfaces and aid the
integration of landforms into the surrounding landscape. Seeding and/or planting will be undertaken prior to the
wet season as soon as possible after earthworks using seed and plants native to Koolan Island;
•
Where necessary, fertilizer will be applied to offset the loss of nutrients and soil microbiota associated with loss of
topsoil; and
•
Rehabilitation and closure procedures will include measures to address specific habitat types of listed fauna.
Geotechnical investigations will be undertaken to determine the optimum final landform of the mine pit walls to ensure
stability of the landform.
•
An abandonment bund wall will be constructed around the perimeter of open pit voids greater than 5m in depth;
•
The bund wall will be constructed outside the area designated as being susceptible to wall collapse; and
•
The location and design of the abandonment bund will be in accordance with procedures detailed in Safety Bund
Walls around Abandoned Open Pit Mines.
9.1
Where required, additional earthworks will be undertaken on those areas of the pit walls that are safely accessible to
improve long term structural stability and facilitate revegetation.
Hand seeding will be undertaken where access is available to improve long term stability, particularly in the erosion
prone haematite-poor grey band material.
Seawall
Waste Dumps
To breach the seawall to below the low water level to
reinstate the natural tidal movement of the area.
The breaching of the seawall will be designed to minimise the impact to coastal habitats and allow for re-establishment
of marine biota on disturbed areas. This strategy will be reviewed with stakeholders and the Responsible Authority
prior to closure.
To ensure that the profile of the waste rock dump final
structure is safe, stable, blends into the surrounding
landscape and not prone to erosion.
The waste dumps will require extensive earthworks and subsequent seeding and revegetation to ensure they are stable
and blend into the surrounding landscaped.
•
The waste rock and slope gradients will be capable of
withstanding the intense rainfall events of the wet
season.
A sufficient cover of vegetation will be established to
minimise erosion resulting from the impact of severe
Waste Dumps will be designed to ensure that the profile of the final structure is safe, stable and not prone to
erosion;
•
Dumps will be designed so that after rehabilitation they blend into the surrounding landscape;
•
Adequate drainage control will be implemented to ensure that erosion does not occur;
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9.2
9.3
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Conceptual Closure Plan
Aspect
Objective(s)
rains on dry soils.
Borrow Pits
The profile of borrow pits final structure is safe, stable,
blends into the surrounding landscape and not prone to
erosion.
Management Actions
•
Outslopes will be designed at less than 20o or lower if required for geotechnical reasons;
•
The dump surface will be a concave slope which are more stable and are less prone to erosion;
•
The tops of the waste dumps will be designed to contain run-off so as not to cause erosion on the sides of the
dumps;
•
Dump surface will be covered with 4 m of clean fill and if available, topsoil to a depth of 100m;
•
Both the tops and the side of the waste dump will be contour ripped to encourage infiltration of rainfall; and
•
Waste dumps will be seeded or planted with local species.
Borrow pits will be progressively rehabilitated as soon as possible following pit closure. The sides of the pits will be
battered to a maximum slope of 20 °. If required, diversion drains and upslope windrows, will be utilized to divert
surface water flow from entering the pit causing ponding and erosion. Pits will be rehabilitation as per the strategy
detailed in Section 8.
Relevant
Section(s)
9.4
A sufficient cover of vegetation will be established to
minimise erosion resulting from the impact of severe
rains on dry soils.
Dewatering
All infrastructure associated with dewatering is
removed.
All infrastructure associated with dewatering will be removed and disposed of appropriately.
9.5
Impact on the marine environment from dewatering
operations is minimised.
Haulage & Ore handling
If not required by another part, all infrastructure
associated with haulage and ore handling is removed.
Disturbed areas are reshaped to blend into the
landscape, manage drainage and rehabilitated.
Ship Loader
If not required by another party, all infrastructure
associated with ship loading is removed.
Disturbed areas are reshaped to blend into the landscape
and manage drainage and rehabilitated.
All infrastructure associated with haul roads and ore handing will be removed.
Haul roads, ROM pad, stockpile and other disturbed areas will be reshaped to ensure they blend into the surrounding
landscape and to control rainfall run-off. Areas will then be rehabilitated.
9.6
All infrastructure associated with the ship loader, including any structures in the ocean will be removed.
Disturbed areas will be reshaped to ensure they blend into the surrounding landscape and to control rainfall run-off.
Areas will then be rehabilitated.
9.7
Marine areas will be left to naturally recolonise.
Disturbed marine areas recolonised by marine flora and
fauna.
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Aspect
Power Station
Objective(s)
All infrastructure associated with the power station is
removed.
The area is investigated to determine if any
contamination is present and if so remediation strategies
are developed and agreed with the DoE.
Management Actions
Relevant
Section(s)
All infrastructure associated with power station will be removed.
Once the infrastructure is remove an investigation for contamination will be undertaken. If soil or water contamination
is identified a remediation plan will be developed and agreed with the DoE.
9.8
Disturbed areas will be reshaped to ensure they blend into the surrounding landscape and to control rainfall run-off.
Areas will then be rehabilitated.
Disturbed areas are reshaped to blend into the landscape
and manage drainage and rehabilitated.
Fuel & Bulk Storage
Facilities
All infrastructure associated with fuel and bulk storage
facilities is removed.
Storage areas are investigated to determine if any
contamination is present and if so remediation strategies
are developed and agreed with the DoE.
All infrastructure associated with fuel and bulk storage facilities will be removed.
Once the infrastructure is remove an investigation for contamination will be undertaken. If soil or water contamination
is identified a remediation plan will be developed and agreed with the DoE.
9.9
Disturbed areas will be reshaped to ensure they blend into the surrounding landscape and to control rainfall run-off.
Areas will then be rehabilitated.
Disturbed areas are reshaped to blend into the landscape
and manage drainage and rehabilitated.
Workshops
All infrastructure associated with the workshops is
removed.
Workshop areas and the wash-down bay are
investigated to determine if any contamination is
present and if so remediation strategies are developed
and agreed with the DoE.
All infrastructure associated with workshops will be removed.
Once the infrastructure is remove an investigation for contamination will be undertaken. If soil or water contamination
is identified a remediation plan will be developed and agreed with the DoE.
Disturbed areas will be reshaped to ensure they blend into the surrounding landscape and to control rainfall run-off.
Areas will then be rehabilitated.
9.10
Disturbed areas are reshaped to blend into the landscape
and manage drainage and rehabilitated.
Explosive Storage
All infrastructure associated with the explosive storage
is removed.
Explosive storage areas are investigated to determine if
any contamination is present and if so remediation
strategies are developed and agreed with the DoE.
All infrastructure associated with explosive storage will be removed.
Once the infrastructure is remove an investigation for contamination will be undertaken. If soil or water contamination
is identified a remediation plan will be developed and agreed with the DoE.
9.11
Disturbed areas will be reshaped to ensure they blend into the surrounding landscape and to control rainfall run-off.
Areas will then be rehabilitated.
Disturbed areas are reshaped to blend into the landscape
and manage drainage and rehabilitated.
Landfill
All infrastructure associated with the landfill is
All infrastructure associated with landfill site will be removed.
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Conceptual Closure Plan
Aspect
Objective(s)
removed.
The site is compacted and stable.
Landfill site is investigated to determine if any
contamination is present and if so remediation strategies
are developed and agreed with the DoE.
Management Actions
Relevant
Section(s)
Once the infrastructure is remove an investigation for contamination will be undertaken. If soil or water contamination
is identified a remediation plan will be developed and agreed with the DoE. DoE Karratha has advised that there is not
a requirement to undertake testing for landfill gases.
Disturbed areas will be reshaped to ensure they blend into the surrounding landscape and to control rainfall run-off.
Areas will then be rehabilitated.
Landfill site is capped by a cover of low permeable
material to a depth of 300mm.
Landfill area is reshaped to blend into the landscape and
manage drainage and rehabilitated.
Bioremediation Facility
Accommodation
All infrastructure associated with the Bioremediation
Facility is removed.
Closure of the bioremediation landfarm will not be undertaken until all areas were contamination may occur have been
investigated and remediated to agreed levels with the DoE.
Bioremediation Facility is investigated to determine if
any contamination is present and if so remediation
strategies are developed and agreed with the DoE.
On completion of bioremediation, the remediated soil will be removed and utilised in rehabilitation of disturbed area.
Sampling of the natural ground surface beneath the bioremediation facility will be undertaken to determine if any
contamination is present. Groundwater monitoring may be required if impacted material has leached into underlying
soils and the potential exists for groundwater contamination.
Disturbed areas are reshaped to blend into the landscape
and manage drainage and rehabilitated.
Once the bioremediation landfarm area has been investigated and any contamination remediated, infrastructure
associated with bioremediation landfarm will be removed and the area reshaped to ensure they blend into the
surrounding landscape and to control rainfall run-off. Areas will then be rehabilitated.
If not required by another party, all infrastructure
associated with the accommodation facility will be
removed.
All infrastructure associated with accommodation facility will be removed, if not required by another party.
Areas were sewerage and grey water were managed will
be investigated to determine if any contamination is
present and if so remediation strategies are developed
and agreed with the DoE.
9.13
Once the infrastructure is remove an investigation for contamination in the areas where sewerage and grey water were
managed will be undertaken. If soil or water contamination is identified a remediation plan will be developed and
agreed with the DoE.
Disturbed areas will be reshaped to ensure they blend into the surrounding landscape and to control rainfall run-off.
Areas will then be rehabilitated.
9.14
Disturbed areas are reshaped to blend into the landscape
and manage drainage and rehabilitated.
Administration Offices
If not required by another party, all infrastructure
associated with the administration offices will be
removed.
Disturbed areas are reshaped to blend into the landscape
and manage drainage and rehabilitated.
All infrastructure associated with administration offices will be removed, if not required by another party.
There will be no storage or use of chemicals within the office areas and hence the site will not need to be investigated
for contamination.
9.15
Disturbed areas will be reshaped to ensure they blend into the surrounding landscape and to control rainfall run-off.
Areas will then be rehabilitated.
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Koolan Island Iron Ore Mine and Port Facility
Conceptual Closure Plan
Aspect
Public Access and Safety
Aspects
Objective(s)
Management Actions
To ensure that disturbed areas are left stable and free of
infrastructure and waste.
Signs clearly stating the risk to public safety and prohibiting unauthorised public access will be erected around the site,
particularly in areas near open pits.
To restrict access to areas that cannot be made safe
through rehabilitative techniques.
On cessation of mining all roads leading to the pits will be closed.
Relevant
Section(s)
10.0
Additional safety bunds will be constructed to minimise the potential risk to the public safety of inadvertent access to
abandoned open pits
Records Management
and Reporting Schedules
To provide clear, detailed and comprehensive
information on all aspects of the mines operating and
closure history.
Records of the history of the site following closure will be preserved to facilitate future land use planning.
Reporting procedures will be established to ensure that results of all trials and actions including remediation works and
monitoring are properly recorded, referenced, and available for long-term reference.
Prior to relinquishment or surrender of tenure, records of the site development will be submitted to the Responsible
Authority.
The types of records required by the Responsible Authority will include the following:
Monitoring
To provide feedback on
•
•
final landform stability;
marine environment recolonisation and water
quality;
•
Geological records, including drilling data;
•
Plans and surveys of surface facilities;
•
Mining and production records;
•
Locations, quantities and qualities of stored waste dumps;
•
Location, quantities and types of waste disposed in the landfill;
•
Site specific surveys or studies; and
•
Mine Closure Plan.
11.0
The implementation of a monitoring programme is crucial in recording the success or otherwise of the completion
criteria, as well as validating agreed criteria for relinquishment (Chamber of Minerals and Energy, 1999). Monitoring
will address the following areas:
12.0
•
Biological (flora and fauna);
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Koolan Island Iron Ore Mine and Port Facility
Conceptual Closure Plan
Aspect
Objective(s)
Management Actions
•
surface and groundwater quality;
•
Marine environment;
•
public safety issues; and
•
Surface and groundwater;
•
rehabilitation and revegetation programs.
•
Public safety; and
•
Landform stability.
To identify potential and actual impacts in order that
remedial work can be implemented.
Relevant
Section(s)
In summary the monitoring proposed is as follows:
•
Annual assessment of rehabilitated areas to monitor the re-establishment of vegetation on all areas disturbed by
mining activities i.e. waste dumps, stockpiles, pit walls, infrastructure area, haul and access roads etc.;
•
Annual assessment of surface and groundwater quality to ensure water quality in disturbed areas is similar to that
in undisturbed areas;
•
Once off assessment of the stability of final landforms by a suitable qualified engineer. Monitoring will then be
undertaken as per the stability assessment recommendations;
•
Annual assessment of rehabilitated coastal habitats to monitor the re-establishment of marine biota and water
quality in areas disturbed by the seawall and ship loader;
•
Assessment of identified aboriginal heritage site on closure of the site to ensure they have not been disturbed;
•
Assessment of weeds and pests on closure of the site to identify if any new outbreaks have occurred due to
Aztec’s operations;
•
Assessment of flora and fauna on closure of the site to identify if any impacts have occurred due to Aztec’s
operations; and
•
Monitoring of all safety bunds, fencing and signage on an annual basis to ensure that all public safety aspects are
adequately addressed.
Monitoring will identify the need for remedial work at an early stage. Monitoring plans will be developed in
consultation with the appropriate regulatory agency and will include agreed actions should monitoring identify issues
that could lead to agreed completion criteria not being met.
Monitoring will be undertaken by Aztec until the agreed completion criteria have been met.
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Conceptual Closure Plan
REFERENCES
ANZMEC/MCA (2000). Strategic Framework for Mine Closure. Australian and New Zealand
Minerals and Energy Council and Minerals Council of Australia. Canberra, ACT.
Australian Mining Industry Council (1989). Mine Rehabilitation Handbook.
Chamber of Minerals and Energy of Western Australia Inc (1999). Mine Closure Guidelines for
Minerals Operation in Western Australia.
Department of Environment (1996). Code of Practice for Country Landfills.
Department of Environment (2004). Bioremediation of Hydrocarbon-Contaminated Soils in
Western Australia. Contaminated Sites Management Series.
Department of Minerals and Energy (1996). Guidelines for Mining in Arid Environments.
Department of Mines & Energy, WA.
Department of Minerals and Energy (1997). Safety Bund Walls around abandoned Open Pit
Mines.
Department of Minerals and Energy (1998). Geotechnical Considerations in Open Pit Mines
Draft.
Department of Minerals and Energy (2001). Environmental Notes on Mining - Waste Rock
Dumps Issue Number 1 January 2001
Department of Industry and Resources (1997). Safety Bund Walls around Abandoned Open Pit
Mines Guideline. December 1997.
Environment Protection Agency (1995). Best Practice Environmental Management in Mining –
Rehabilitation and Revegetation.
Minerals Council of Australia (February 2000). Code for Environmental Management.
URS Australia Pty Ltd. (2005). Phase 1 and Phase 2 Baseline Environmental Site Assessment –
Koolan Island Iron Ore Project. Unpublished report prepared for Aztec Resources Limited.
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