ecologia KOOLAN ISLAND IRON ORE MINE AND PORT FACILITY Conceptual Closure Plan E N V I R O N M E N T

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1 Photos at least 1 up to 3 project/survey specific to completely fill the white box, DO NOT CHANGE SIZE OF WHITE BOX KOOLAN ISLAND IRON ORE MINE AND PORT FACILITY E N V I R O N M E N T

2 Document Status Rev Author Reviewer/s Date No. Final K. Bleby R. Mason V Ee Nov 05 Dudley Kingsnorth Approved for Issue Name Distributed To Date EPA Nov 05 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 Environment. Restrictions on Use This report has been prepared specifically for Aztec Resources Limited. Neither the report nor its contents may be referred to or quoted in any statement, study, report, application, prospectus, loan, or other agreement document, without the express approval of Aztec Resources Limited and/or Environment. Environment 76 Thomas Street WEST PERTH WA 6005 Phone Fax Page i

3 CONTENTS SUMMARY INTRODUCTION PREVIOUS OPERATIONS CURRENT OPERATIONS PLANNED OPERATIONS PROJECT CLOSURE PLAN SCOPE PROJECT CLOSURE OBJECTIVES LEGAL OBLIGATIONS LEGISLATION GUIDELINES AND CODES OF PRACTISE COMPLETION CRITERIA OBJECTIVE PROPOSED COMPLETION CRITERIA CONTAMINATED SITES OBJECTIVE CONTAMINATED SITES INVESTIGATION AND MANAGEMENT DECOMMISSIONING OBJECTIVE REMOVAL OF INFRASTRUCTURE DEVELOPMENT OF FINAL LANDFORMS OBJECTIVE SHAPING OF LANDFORMS REHABILITATION STRATEGIES OBJECTIVES REHABILITATION MONITORING OF REHABILITATION PROPOSED CLOSURE STRATEGIES MINE PITS CLOSURE OBJECTIVE CLOSURE STRATEGY COMPLETION CRITERIA SEAWALL CLOSURE OBJECTIVE CLOSURE STRATEGY COMPLETION CRITERIA WASTE ROCK MANAGEMENT CLOSURE OBJECTIVE CLOSURE STRATEGY COMPLETION CRITERIA BORROW PITS OBJECTIVES CLOSURE STRATEGY COMPLETION CRITERIA DEWATERING OBJECTIVES CLOSURE STRATEGY COMPLETION CRITERIA...33 Page ii

4 9.6 HAUL ROADS, ROM PAD, STOCKPILE AND ORE PROCESSING OBJECTIVE CLOSURE STRATEGY COMPLETION CRITERIA JETTY AND SHIP LOADER OBJECTIVE CLOSURE STRATEGY COMPLETION CRITERIA POWER STATION OBJECTIVE CLOSURE STRATEGY COMPLETION CRITERIA FUEL AND BULK STORAGE FACILITIES OBJECTIVE CLOSURE STRATEGY COMPLETION CRITERIA WORKSHOPS OBJECTIVE CLOSURE STRATEGY COMPLETION CRITERIA EXPLOSIVE STORAGE OBJECTIVE CLOSURE STRATEGY COMPLETION CRITERIA LANDFILL OBJECTIVE CLOSURE STRATEGY COMPLETION CRITERIA BIOREMEDIATION FACILITY OBJECTIVES CLOSURE STRATEGY COMPLETION CRITERIA ACCOMMODATION OBJECTIVES CLOSURE STRATEGY COMPLETION CRITERIA ADMINISTRATION OFFICES OBJECTIVE CLOSURE STRATEGY COMPLETION CRITERIA PUBLIC ACCESS AND SAFETY ASPECTS OBJECTIVES STRATEGY RECORDS MANAGEMENT AND REPORTING SCHEDULES OBJECTIVE STRATEGY MONITORING OBJECTIVES STRATEGY SUMMARY OF MANAGEMENT ACTIONS 47 REFERENCES 55 Page iii

5 FIGURES 1.1A PROPOSAL STUDY REGION B PROJECT LOCATION BHP MINING OPERATIONS AT ARBITRATION COVE PRIOR TO 1993 (TOP FOUR PHOTOS) AND A VIEW OF ARBITRATION COVE AT PRESENT (JULY 2004) PROPOSED OPERATIONS ON KOOLAN ISLAND LAYOUT ON KOOLAN ISLAND...29 TABLES 1.1 SUMMARY OF KEY CHARACTERISTICS ASSOCIATED WITH THE PROPOSAL SUMMARY OF MANAGEMENT ACTIONS...47 Page iv

6 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 On May , 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 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 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. Page 5

7 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 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 , 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 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 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 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; Page 6

8 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. Page 7

9 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. Page 8

10 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. Page 9

11 Table 1.1 Koolan Island Iron Ore Mine and Port Facility Summary of Key Characteristics associated with the Proposal Component Key Aspect Description Mining Dewatering of Main Pit Ore Processing Ship loading Infrastructure General 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 Ore Deposits 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 Depth of mine pits Eastern Pit: Current 60m Final 115 m below ground level Depth of water table Generally > 100 m below ground level Ore Type High grade hematite (61-68%) Commence construction early 2006 Proposed Project Schedule Commence production in early million tonne per year Ore Mining Rate (Year 1 2 Mt, Year Mt, Year Mt and Year Mt) Project Life Span 9 Years + Approximate Year of 2015 Decommissioning Stockpile of ROM material Capacity: 100,000 Tonne; Area: 10 ha Waste Dump Capacity and Area Capacity: 124 Mm 3 ; Area: 280 ha Strip Ratio (waste : ore) Approximated at 6:1 Amount of land disturbance 540 ha (45% previously disturbed) Construction of Sea Wall 300 m wall across Arbitration Cove, 75 m wide at the base, 15 m high Initial Dewatering: Approximately 7 Mm 3 of sea water at 300 l/s Dewatering Maintenance: Ongoing rate of l/s Turbid water will be placed in sedimentation pond prior to discharge into ocean Primary Crushing and Screening 2 stage dry crushing and screening plant to produce fines and lump product. Ship loading Product will be stockpiled near the ship loader for direct loading Project access Inter-island: Aircraft Intra-island: Haul and access roads Power : Diesel fuelled 2 MW power station Power Source Generators: 5 x 0.5 kva generators Water Source Fresh water will be extracted from three existing bores, 75 kl/day potable water Workshops Heavy and light equipment maintenance workshops Equipment Conventional heavy and light mobile equipment Fuel Consumption Approx 10.6 ML/year Ore will be transferred from the stockpiles to the Ore Handling ship loader via a conveyor system A ship loader and jetty will be re-established to Port Facility enable ship loading Accommodation Single persons village Work force 200 persons, with fluctuations during peak periods; fly in, fly out Solid Waste Maximum of 300 tonnes per year Bulk Transport of material Via Barge from Derby / Broome, or coastal shipping Page 10

12 Figure 1.1a Proposal Study Region. Figure 1.1b Project Location (inset box see Figure 1.1a). Page 11

13 BHP mining operations at Arbitration Cove prior to BHP ship loading wharf facilities at Arbitration Cove prior to Recent photograph of Arbitration Cove taken in July 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). Page 12

14 Figure 1.3 Proposed operations on Koolan Island. Page 13

15 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. Page 14

16 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. 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 Page 15

17 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. Page 16

18 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 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. 4.2 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; Page 17

19 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. Page 18

20 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. Page 19

21 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 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. Page 20

22 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 Page 21

23 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. Page 22

24 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. Page 23

25 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. Page 24

26 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 Page 25

27 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. Page 26

28 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 Closure Objective Ensure pit void and walls are structurally stable; and Ensure public safety by restricting access to remaining pits 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 Page 27

29 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 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). Page 28

30 Figure 9.1 Layout of Koolan Island. Page 29

31 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 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. 9.3 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 Mm 3 ; 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 Mm 3 of waste rock; Page 30

32 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 Mm 3 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 Mm 3, 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 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 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; Page 31

33 Adequate drainage control will be implemented to ensure that erosion does not occur; Outslopes will be designed at less than 20 o 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 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 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 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 Completion Criteria Borrow pit slopes are below 20 o ; Page 32

34 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 Objectives All infrastructure associated with dewatering is removed; and Impact on the marine environment from dewatering operations is minimised Closure Strategy All infrastructure associated with dewatering will be removed and disposed of as per Section 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. Page 33

35 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 m 3 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 Objective All infrastructure associated with haulage and ROM ore storage is removed; and Disturbed areas are reshaped to blend into the landscape, and rehabilitated 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 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. Page 34