- 3.2.1. End use objectives and final concept plan
- 3.2.2. Progressive rehabilitation
- 3.2.3. Landscaping and screening
- 3.2.4. Soil removal
- 3.2.5. Soil respreading
- 3.2.6. Soil stockpiling
- 3.2.7. Seedbed preparation
- 3.2.8. Revegetation
- 3.2.9. Alternative revegetation methods
- 3.2.10. Roads, tracks and other compacted areas
- 3.2.11. Runoff and erosion control
- 3.2.12. Removal of plant and equipment
- 3.2.13. Site safety and security
- 3.2.14. Maintenance and monitoring
Part 4. Other environmental aspects of work plans
- 4.1 Exploration
- 4.2 Mining
- 4.2.1. Statutory requirements
- 4.2.2. Environmental planning
- 4.2.3. Vegetation removal and buffers
- 4.2.4. Flora and fauna protection
- 4.2.5. Noise
- 4.2.6. Vibration
- 4.2.7. Dust and other emissions to air
- 4.2.8. Traffic movements
- 4.2.9. Runoff and erosion control
- 4.2.10. Water storage capacity and discharge
- 4.2.11. Process water requirements and dewatering
- 4.2.12. Waste disposal
- 4.2.13. Management of process chemicals, hydrocarbons and explosives
- 4.2.13.1. Cyanide
- 4.2.13.2. Mercury
- 4.2.14. Acid mine drainage (AMD)
- 4.2.15. Tailings retreatment
- 4.2.16. Pest plants and animals
- 4.2.17. Heritage
- 4.2.18 Risk management
Appendix 1. Work plan information
Appendix 2. Sources of further information
1. Preamble
The purpose of these guidelines is to provide assistance to mining licensees, under the Mineral Resources (Sustainable Development) Act 1990.
The guidelines are an advisory document. They provide guidance on matters that the department generally looks at in assessing plans. They do not set requirements for plans, beyond those statutory requirements, which are already in place. Nor are they intended to be a text on environmental management and rehabilitation techniques.
Publications such as the Mine Rehabilitation Handbook produced by the Australian Mining Industry Council and Best Practice in Environmental Management in Mining produced by the Federal Environment Protection Agency are available for this purpose.
In addition to the guidelines, we can provide direct assistance to licensees on the preparation of their work plan and the gaining of authorities from other government agencies. Licensees are advised to contact the department at an early stage in the preparation of their plan.
A wide range of environmental and rehabilitation matters are addressed in the guidelines. Not all of these will be applicable to every work plan. This is particularly so in the case of small mining operations (less than 5 hectares), and licensees should carefully consider which matters are relevant to their operations. In some cases, matters, which are not covered here, should also be addressed in the Plan.
Some mining proposals will be the subject of an environmental effects statement (EES). Most of the matters covered in the guidelines would also be covered in an EES. In cases where project design is at an advanced stage when the EES is prepared, it may be possible to combine the work plan and EES into one document.
More commonly they will be separate documents, with the EES being more conceptual in nature and the detailed design being incorporated in the work plan. Where an EES has previously been prepared, the work plan should make reference to its analyses and findings but need not report its studies in detail.
2. Requirement for work and rehabilitation plans
The Mineral Resources (Sustainable Development) Act 1990 (MRSDA) requires that a licensee proposing to do work under a mining licence or an exploration licence must submit a work plan.
In the case of a mining licence, the work plan must include a rehabilitation plan. This is a requirement whether the work proposed is mining or exploration.
3. Rehabilitation plans
3.1 Statutory requirements and consultation
Some general guidance as to the content of rehabilitation plans is provided by the MRSD Act, which requires that rehabilitation be progressive and that the plan takes account of:
- any special circumstances of the land, and
- the surrounding environment, and
- the need to stabilise the land, and
- the desirability or otherwise of returning agricultural land to a state that is as close as reasonably possible to its state before the mining licence was granted.
Regulation 43 of the Mineral Resources (Sustainable Development) (Mineral Industries) Regulations 2019 prescribes requirements for rehabilitation plans. Note that new rehabilitation plan requirements will commence from 1 July 2020.
The MRSD Act requires that the rehabilitation plan be prepared by the licensee after consultation with the owner of the land, if the land is private, or the land manager (part of the Department of Environment, Land, Water & Planning), if the land is Crown land.
The regulator will require some verification, preferably written that the necessary consultation has taken place.
In the case of a rehabilitation plan for work on Crown land, the MRSD Act also requires that the regulator reach agreement with the land manager as to the amount of the rehabilitation bond. This may be difficult if the content of the rehabilitation plan has not already been agreed between the licensee and the land manager. To avoid delay to approvals, the licensee should make every effort to reach agreement as to the content of the plan.
3.2 General principles
+ Expand all - Collapse all3.2.1 End use objectives and final concept plan
Rehabilitation is an integral part of mining operations. It should be planned from the outset and, as far as practicable, undertaken during the operational life of the mine.
Rehabilitation planning should incorporate two elements. The first is a final concept plan. This need not be detailed but it should establish expected end use/s of the site and its general characteristics at the completion of rehabilitation. It provides the basis for rehabilitation activities throughout the life of the project.
There are a variety of possible end uses for mine sites. Options for open cut pits include water bodies, landfill, return to agriculture or native vegetation and industrial/commercial use. In the case of long lived operations, it should not necessarily be assumed that proposed end uses, such as landfill or industrial development which may require further planning and environmental approvals, will be acceptable at some future time.
Proposals should be practical and currently achievable. This approach will most often focus on the return of the site to a use similar to that before mining and involve basic landscaping and revegetation.
The end use objective for most agricultural land is the return of the land to a productivity level comparable with that prior to the mining operation. However, with the landowner's agreement, a change of land use need not be precluded. For example, former cropping or grazing land could be converted to wood production plantations or water storage.
The final concept plan should include a schematic plan showing salient features of the land following rehabilitation. These might include revegetated areas, pit faces, roads, drainage lines and water bodies.
3.2.2 Progressive rehabilitation
The second element of rehabilitation planning is the progressive plan. This should set out in some detail the proposed rehabilitation works, how they will be undertaken and their sequence and timing.
The plan should specify rehabilitation standards or "completion criteria" which will be achieved.
These can cover a wide variety of matters, including:
- native revegetation – plant growth, plant density, species diversity
- productivity of rehabilitated agricultural land
- final slopes of pits, waste dumps, dam walls, etc.
- chemistry and levels of suspended solids of runoff waters.
It is generally not sufficient only to cite compliance with licence conditions or regulatory agencies' requirements.
The progressive plan may cover the life of the licence/operation or a shorter period, say two to five years, with updates submitted later. Provision is made for staged rehabilitation plans, by variation of the work plan, in the MRSDA (section 41).
A site plan/s should be included. The site plan should indicate the location of proposed rehabilitation works and the progress of rehabilitation over time.
Topsoil and waste dumps, bunding, final pit faces, benches, areas of landscaping and revegetation, roads, drains and dams should be featured.
3.2.3 Landscaping and screening
Landscaping should leave a final landform visually compatible with the surrounding natural landscapes, ensure that the land is stable and will not erode, and provide an adequate substrate for revegetation.
Rehabilitation planning should consider critical views and incorporate landscaping, screening, buffers and a site layout which minimise views of exposed faces, unvegetated waste heaps, stockpiles and plant.
Thoughtful bunding, vegetation screening, progressive rehabilitation and selection of working directions can all reduce visual impact. Angular or straight landforms, flat surfaces and steep faces should be avoided where possible.
Erosion will result where slopes are too steep or too long. In soft, readily erodible material recommended slopes are 1V:3H or shallower. Long slopes should be broken by benches.
The rehabilitation plan should include analysis of the visual impact from critical views and specify final slopes.
3.2.4 Soil removal
Retention of soil is the key to revegetation. Topsoil, together with leaf and plant litter, should be removed and stockpiled separately from underlying material. Depending on the soil profile, up to 300 mm of topsoil may need to be stripped.
The rehabilitation plan should indicate the location and depth of soil stripping.
3.2.5 Soil respreading
Soil should be respread as soon as possible after stripping in order to maximise its fertility, seed viability and microbial activity.
The rehabilitation plan should indicate the approximate depth of respread soil and its location. Consideration may also need to be given to the respreading techniques used, with a view to minimising soil compaction that can inhibit later revegetation.
3.2.6 Soil stockpiling
In cases where stripped soil cannot be respread immediately, it should be stockpiled. Stockpiles should be established as close as practicable to areas to be rehabilitated. They should be low (generally less than 2m in height), gently battered and located away from drainage lines.
The plan should include their locations and dimensions.
3.2.7 Seedbed preparation
The seedbed is the medium for plant growth. Following the respreading of soil, treatment may be required to prepare the seedbed for planting.
The treatments which are appropriate to a particular case will depend on the physical and chemical properties of the soil, the species used in revegetation and other factors such as climate and slope.
Soil treatments that may be required include:
- deep contour ripping or ploughing
- application of chemical and organic fertilisers
- application of gypsum, lime and trace elements
- covering with mulch or brush
- planting of cover crop
- hydromulching
- bituminous spraying
- application of weedicide or weed removal
The rehabilitation plan should indicate the proposed seedbed treatments and the reasons for their selection. Advice from the landowner or land manager may be sufficient to determine the appropriate treatments.
Alternatively, studies of soil characteristics and other factors particular to the site may be required. For instance, chemical analyses of soils might be necessary to determine the appropriate type and application rate of fertiliser or the application rate for gypsum.
On some sites, particularly in old mining areas, there is little or no topsoil left on site for stripping and respreading. Preparation of seedbeds without soil has been quite successful in many cases.
It involves the same range of treatments listed above, although application rates of fertilisers will generally need to be higher. Importing of soil is not recommended, especially in areas of native vegetation, because of the risk of the imported soil introducing weeds or plant diseases.
3.2.8 Revegetation
Revegetation is usually the primary objective of rehabilitation and is often the measure of its success.
Revegetation with native species may involve direct seeding, planting tube stock, natural regeneration or any combination of these. A variety of seeding techniques can be used, including hand broadcasting, mechanical broadcasting or drilling.
Species selection is important. Species should be local to the area and suitable for the on-site conditions, such as soil type and drainage. In areas of native vegetation, species should reflect the original vegetation. A pre-mining vegetation survey may be required to determine the appropriate species mix.
The rehabilitation plan should indicate the proposed revegetation method (seeding, tube stock, and natural regeneration) and the general mix of species. The source of seed or tube stock should also be indicated. Vegetation cleared for the operation should, where possible, be the primary source of seed. This can be supplemented with seed collected locally.
Tube stock can be supplied by local nurseries or propagated on-site. Regional Department of Environment, Land, Water & Planning (DELWP) offices can usually provide local advice on species selection and sources of seed and tube stock.
The objective of revegetation for most agricultural land is the return of the land to productivity. Accordingly, seedbed preparation and crop types should be determined in close consultation with the landowner and included in the rehabilitation plan.
Catchment Advisory Services, DELWP can also provide advice on seedbed preparation and crops.
3.2.9 Alternative revegetation methods
Licensees may wish to use revegetation methods other than those described above. Such alternative methods are acceptable provided that the rehabilitation standards achieved are at least equal to those that would be expected using conventional methods.
Where alternative methods are proposed they should be supported by examples of their success elsewhere or a program to trial the methods should be included in the plan.
Where trials are proposed, their success will ultimately determine the acceptability of the method. Revegetation directly onto tailings is one instance where trials could be used to establish the viability of an alternative method.
3.2.10 Roads, tracks and other compacted areas
Rehabilitation of roads and tracks starts at the time of construction, when rehabilitation of embankments and fills should be undertaken.
Final rehabilitation of tracks and roads should only be undertaken following agreement with the landowner or land manager, as to whether the road or track will be retained after operations cease.
The rehabilitation plan should cover progressive rehabilitation, decommissioning and final rehabilitation of those tracks and roads not retained.
Advice on such rehabilitation is provided in the Guidelines for exploration and rehabilitation of exploration sites and, where appropriate, should be referred to in the rehabilitation plan.
Other highly compacted areas such as loading areas, carparks and stockpile pads may require special treatment, such as deep ripping or removal of compacted material, prior to respreading of topsoil. Such measures should be included in the rehabilitation plan.
3.2.11 Runoff and erosion control
In most instances, the measures required for long-term run-off and erosion control on rehabilitated sites are similar to those required in the operational phase of mining (see 4.2.9).
Mine site water management handbook published by the Minerals Council of Australia and Guidelines for minimising soil erosion and sedimentation from Construction Sites in Victoria published by the Soil Conservation Authority provide advice on a range of techniques that can be applied to control runoff and erosion on mine sites.
The rehabilitation plan should outline permanent control measures, such as drainage channels and dams, which are to be incorporated in the final land form.
3.2.12 Removal of plant and equipment
The rehabilitation plan should cover removal of plant, equipment and rubbish at the completion of works.
Particular attention should be given to removal of plant foundations and underground facilities such as pipes and storage tanks. Rubbish should be disposed of at an appropriate rubbish disposal site.
3.2.13 Site safety and security
Mining and exploration sites must be left in a condition that ensures the safety of the public. The rehabilitation plan should cover the security of the site and public safety, following cessation of operations.
This may require limiting public access by fencing and barring of vehicular access tracks. Where applicable, the safety and stability of the pit faces, access to underground workings and safety of water bodies should be addressed.
3.2.14 Maintenance and monitoring
Maintenance of rehabilitated sites is often the difference between the ultimate success or failure of rehabilitation. Both during and following rehabilitation works, routine maintenance of structures such as drains, dams, silt traps and fencing should be undertaken.
Maintenance of revegetation may also be required, in the form of replanting or reseeding in failed areas, weed control, watering, pest control and installation/repair of tree guards and fencing for protection from grazing.
Monitoring of rehabilitation will determine whether rehabilitation objectives and requirements are being achieved. In particular, performance against "completion criteria" should be monitored during and following rehabilitation.
The rehabilitation plan should propose schedules for maintenance and monitoring.
3.3 Exploration
Guidelines for rehabilitation of exploration sites are provided in the Guidelines for exploration and rehabilitation of exploration sites. Plans need not restate the provisions of these guidelines, but should refer to them where appropriate.
3.4 Shallow surface mining
The principles set out above cover most aspects applicable to shallow surface mining. The following matters should also be addressed in the rehabilitation plan:
- Progressive rehabilitation is possible in many cases. A staged program should be developed, covering the sequence and timing of clearing, mining, back filling and rehabilitation, and indicating the maximum areas open or unrehabilitated at any one time.
- Proposals should indicate the materials to be used for the refilling of pits, the extent to which pits will be refilled and the resulting changes to land form. Of particular importance, is battering of final faces and the integration of the rehabilitated area into the surrounding landscape.
- Some alluvial deposits will be mined on and around drainage lines. Plans should include any proposals for buffer zones around creeks, temporary or permanent diversion of creeks, and the final form, grades and erosion control structures of reconstructed drainage channels.
3.5 Opencut pits
Open cuts most often change the land form permanently. Except for landfill operations, back filling of deeper pits is generally not practical due to cost or lack of available fill material. It may however be a viable option for shallower pits.
Where voids are left, the following matters should be addressed in the rehabilitation plan:
- The final pit slope and geometry should ensure that the pit walls are structurally stable and allow for the placement and long term stability of the rock fill (overburden) and soil required for revegetation. Plans should include cross-sections showing rock faces, benches and thickness of rock fill and soil cover placed on rock surfaces.
- The shaping of the final pit walls may involve either battering or benching or a combination of these. The methods to be used to shape the walls, such as backfilling on benches and collapse of faces by blasting should be indicated.
- Where possible, final pit walls and pit floors should be progressively rehabilitated. The plan should indicate the sequence and timing of rehabilitation works and the expected maximum length of faces and area open or unrehabilitated at any one time.
- Ripping or light blasting of pit floors and benches may be required to break up solid rock, prior to placement of rock fill and soil and revegetation.
- Where open cuts intersect the water table, a permanent water body will be created unless the pit is back filled to a level above the water table. Information on the depth of the water table and groundwater quality will be required to ascertain whether a water body should be part of the final rehabilitation proposal. If a water body is proposed, the regional water authority and DELWP may also require studies of the impact of the open cut on aquifer systems, recharge areas, groundwater users and local rivers and streams.
- Pit safety and security should have high priority as the risk to public safety can be high. Measures should be included to limit public access to open cut sites. Design of final pit faces, especially upper faces, and water bodies should minimise risk to the public.
3.6 Underground mines
Matters that should be addressed in the rehabilitation plan include:
- Removal of surface facilities and site rehabilitation.
- On completion of mining, surface access to the works by shafts, ad its or declines should be permanently closed off to the public and the site made secure. Details of proposals for capping or back filling should be included.
- Groundwater will be encountered in many underground workings. The plan should indicate if any long-term discharges of groundwater to surface are likely to result from mining, the quality of that water and measures that will be taken to stop discharge or treat the discharged water. Where mining is below the oxidised zone and the ore body contains sulphides, particular attention should paid to long term control of acidic and metal contaminated waters. Discharge of water offsite generally requires approval from the Environment Protection Authority (EPA) as outlined in section 4.2.10.
3.7 Tailings retreatment
The rehabilitation principles for mines generally apply to tailings retreatment. The following matters may also require attention in the rehabilitation plan:
- Gold mining tailings often carry high levels of arsenic and mercury. Rehabilitation should ensure that the retreated tailings are confined in properly constructed and rehabilitated tailings dams, so as to prevent contamination.
- Tailings removal should ensure that all contaminated material is removed or stabilised prior to revegetation.
- Tailings removal sites will often have little, if any soil available for rehabilitation.
Original soils underlying the tailings may be contaminated and should be analysed prior to use in rehabilitation. Where soil is not available or not suitable, the rehabilitation plan should specify the techniques, which will be used to achieve revegetation.
3.8 Tailings dams
The rehabilitation of tailings dams is often a most difficult element of rehabilitation due to their physical instability and chemistry.
At the outset, planning should ensure that sufficient material (rock, clay, sand, and soil) is available for covering of the tailings in final rehabilitation.
Initially the dam must be dried out so that machinery can access the dam surface. Access and rehabilitation can be delayed for years if appropriate measures to aid drying are not in place. The rehabilitation plan should detail measures proposed to hasten drying, such as surface drainage, under-drainage, decant structures and thickening or filtering of wastes.
The plan should address battering of external dam walls to allow effective revegetation and prevent erosion (slopes of 1V: 3H or shallower are recommended), installation of cut-off drains to reduce water flowing onto the dam surface, and long-term collection and treatment of seepage from the dam.
Dam rehabilitation techniques will largely depend on the chemistry of the tailings. For tailings with extremes in pH or high levels of heavy metals, other toxicants or salinity special rehabilitation measures will be required. The plan should detail proposals which may include capping with a low permeability (clay) layer, placement of a coarse layer for drainage and as a capillary barrier, covering with soil and other fill material and crowning of the surface for drainage.
Where tailings are acidic (low pH), lime to neutralise the tailings may be applied. Permanent water cover is an alternative rehabilitation approach for sulphidic tailings with potential for acid generation.
Tailings which are not chemically contaminated or saline, such as those from some gravity separation plants, can generally be revegetated by placing directly onto the tailings, soil and other fill material of sufficient depth to allow root development.
Species selection can be very important and should be addressed in the plan. Shallow rooting species and, for saline tailings, salt tolerant species should be considered. Trialing of different species is also recommended. In some instances, revegetation directly onto tailings has also been successful.
Tailings Containment – Best Practice Environmental Management in Mining published by the Federal Environmental Protection Agency provides further information on tailings management.
3.9 Waste dumps and leach heaps
Well located, landscaped and vegetated dumps can form very effective visual screens for operations. Conversely, bare and eroding dumps can be an eyesore. To minimise visual impact during operations, dump construction and rehabilitation should, where practicable, start on the outer dump perimeter with later dumps inside the rehabilitated perimeter dumps.
For erosion control, final slopes of 1V: 3H or shallower are recommended, with benches to break long slopes.
Where toxic or acid-generating wastes are involved, dumps may require capping with a low permeability (clay) layer and drainage and treatment of contaminated waters.
The rehabilitation plan should indicate dump locations, dimensions, slopes, erosion control measures, capping, drainage and revegetation.
Rehabilitation of leach heaps can be dealt with in much the same manner as other waste dumps. The plan should outline measures that ensure that remnant cyanide in seepage from heaps will be at acceptable levels and will not create a health risk or cause environmental harm in the long-term.
4. Other environmental aspects of work plans
4.1 Exploration
Regulation 41 of the Mineral Resources (Sustainable Development) (Mineral Industries) Regulations 2019 sets out the requirements for an exploration work plan for a licence.
