The Rehabilitation of Abandoned Mining Lands
Abandoned mining lands refers to areas or sites of former mining activity for which no individual, company, or organisation can be held responsible. Such sites have also been called 'derelict' or 'orphan' mines. In recent years, the mining industry agreed to an increase in royalties, a portion of which was to be allocated to a Trust Fund, for the sole purpose of the repair of abandoned mining lands. A summary of recent works can be found in the MRT Annual Review. All current reports on works using funds from the Rehabilitation of Mining Lands Trust Fund can be accessed on the Rehabilitation Map.
Abandoned mine sites may contain hazards to human and animal life in the form of accessible adits, shafts and workings, and there may be associated pollution (such as acid drainage) from old workings and stockpiles. Visual degradation is an issue in some areas, even if the site is now not actively eroding. In some places, ongoing erosion can affect land stability, revegetation efforts and water quality.
These problems have arisen due to government requirements and operational standards being of a lower standard than are in use today. Modern mines are operated in accordance with 'best practices' techniques and government regulation of both exploration and mining is very strict. Bonds are held against both exploration and mining titles and these funds can be used for any rehabilitation, which is left outstanding by the operator.
Establishment of Trust Fund
A Trust Fund was established to fund rehabilitation of land affected by former mining or exploration activities and is defined in the Mineral Resources Development Act 1995 as:
(a) any money appropriated by Parliament for the purposes of this Part; and
(b) any money received from the sale of any building, machinery or property vested in the Crown under section 105(4); and
(c) any security deposit or part of a security forfeited by the Minister under section 198; and
(d) any other money received for the purpose of this Part; and
(e) any money the Treasurer directs to be paid into the Rehabilitation Trust Fund.
The Minister for Mines may: (Mineral Resources Development Act 1995, Section 180.)
(a) cause any abandoned mining land or land affected by former exploration activities to be rehabilitated; and
(b) enter into any contract relating to the environmental rehabilitation of any abandoned mining land or land affected by former exploration activities.
The fund was established after agreement with the Mining Industry to an increase in royalties, the proceeds of which would be used to repair abandoned mining lands.
Trust Fund Committee
A Committee has been established to provide advice to the Minister on the management of the Trust Fund. The committee is comprised of representatives from:
- Mineral Resources Tasmania (MRT),
- Department of Primary Industries, Parks, Water and Environment (DPIPWE),
- Environmental Protection Authority (EPA)
- Resource Management and Conservation (RMC)
- Parks and Wildlife Service (PWS)
- Forestry Tasmania,
- Concrete, Cement and Aggreagates Australia (CCAA)
- Tasmanian Minerals and Energy Council (TMEC).
Challenges for abandoned mine site rehabilitation
Abandoned minesites present a number of challenges which are not common with other land restoration programs, such as:
- The absence of any planning for rehabilitation during the original operation.
- The degraded state of the sites - early miners did not conserve topsoil and sites are often completely bare with denuded expanses of regolith, bedrock and tailings emplacements, which present hostile environments for vegetation.
- Remaining soils are often contaminated and may be acidic after long term exposure to site pollution.
- Inadequate documentation of the operations may which present hazards, including unmarked workings, unstable embankments, and unexpected chemical contamination.
- Acidic water coupled with the uncertain extent of workings, make sealing workings to prevent further water entry or escape, difficult and sometimes, impossible.
- Mining and processing methods which have often spread the impact of activities beyond the precincts of the original site.
- The sites often have heritage and scientific significance.
- Sites may have become the habitat for native fauna and relict populations of native flora, sometimes as a direct result of mine disturbance.
- Most sites are isolated from major settlements so that in many cases cost recovery through subsequent sale of remediated land is not generally feasible.
- The presence of exotic noxious plants is also common.
These features complicate rehabilitation projects necessitating extensive and detailed planning prior to undertaking works.
Aim of Rehabilitation
The aims of rehabilitation are to:
- Remove risks to health and safety.
- Stabilise the site and reduce or remove the impact of erosion and mass movement.
- Where feasible maintain or increase the biological diversity of species in the vicinity.
- Remove or ameliorate sources of site contamination.
- Remove features limiting the beneficial use of the site and its surroundings.
- Improve the visual amenity of the site and its surroundings.
In many instances, work on the site may also require complementary off-site works to protect rehabilitation. It may also be necessary to limit the types of activities permitted on sites either for the short or long term to safeguard the integrity of rehabilitation.
Selection of Sites
Sites which are to be considered for rehabilitation must fit the following selection criteria:
1. The site is to be on Crown Land. Sites on private property will not be considered;
2. The site is to have been worked by private enterprise and not by Government or by Government instrumentality. Gravel pits previously worked by the Hydro Electric Commission, Forestry Tasmania, the Department of Main Roads etc. will not be considered;
3. The site must be abandoned, with the responsibility for rehabilitation resting with the Crown. Current liabilities of existing tenement holders will not be considered. However, work may be done on tenements where the tenement holder has been absolved of responsibility for pre-existing degradation.
Other factors to be considered include:
4. Threats to the safety or health of the public, stock or native flora/fauna;
5. Pollution impacts on adjoining properties or catchments;
6. Erosion or land degradation on/off site;
7. Loss of visual amenity;
8. Public concerns/complaints.
Sites which meet the first three points and most of the points 4-8 can be considered for rehabilitation. However, there are many abandoned mine sites and limited funds. Priorities are set for the sites which are suitable.
Priorities for Rehabilitation
To set priorities for rehabilitation, a means for determining the degree of risk presented by a given site (environmental and safety) is required. Where practicable, this should be quantitative or semi-quantitative while still allowing for other factors to be used in final consideration of a site's eligibility for remediation. Such a method may entail an assessment of the likelihood of risks and the consequences utilising a risk assessment matrix to determine priority sites.
For the purposes of ranking abandoned mines, appropriate category definitions can be assigned. These can be applied to a number of selection criteria, including:
- Area affected
- Water pollution
- Erosion and sediment movement
- Cumulative Impacts - assessed on a catchment management basis.
- Risks to human health
- Public Safety
Determining Rehabilitation Priorities
The Committee has previously agreed that the sites selected for rehabilitation should be prioritised in accordance with:
1. The nature of public risk posed by hazards on the site, assessed by risk analysis.
- Risk, depth of shafts;
- Extent of stoping and excavations;
- Ease of access;
- Population exposed.
2. Scope of impacts - off-site
The extent of the impact and the consequences of impacts on surrounding lands, such as:
- natural areas/National Park;
- orested land; productive forest;
- agricultural land;
- derelict farmland;
- acid drainage;
- siltation; and
- potential for weed infestation to spread.
3. Extent of and potential for further degradation on site
Factors such as the following will be considered:
- area of degradation;
- erosion, stable or actively degrading;
- loss of soil and vegetation;
- weed infestation.
The duration of any potential impact (short or long term) will also be considered, and whether the remediation can be completed in one or two campaigns or will be on-going, requiring extensive maintenance.
4. Visual amenity and social impact
The visual impact of the site is also a factor to be considered. This need not necessarily be related to the size of the site; small sites may be more visually intrusive in sensitive areas than larger sites elsewhere. The social impacts of a site will also be considered
The committee has agreed to a list of sites which are to be rehabilitated. A three year rolling plan has been prepared which lists sites to be repaired as funds permit. This list will be reviewed from time to time and will be amended as new information comes to hand.
Process for Rehabilitation
The process to be followed for the implementation of rehabilitation projects is outlined in this section. Following the approval of a particular project by the Committee a number of steps are required before on ground work can commence. These are as follows:
The Land Use Planning and Approvals Act, 1993 (Lupaa) as it Applies to Rehabilitation on Crown Land
As all rehabilitation projects include on ground work they will fall under the LUPAA and therefore require a Permit from the Local Government.
By following the requirements of this Act a transparent process is followed which includes notification in the local press and public consultation.
The following information is included in the Planning Application:
1. Description of the proposed development
- Stakeholder Consultation
- Proposed Works
- Current and proposed land use
- Staging of the proposed works
- Hours/days of operation
- Heavy traffic movements
- Potentially hazardous operations and/or movements
- Disposal of wastes
- Control of emissions
2. Supporting information
- Scientific and cultural information
In some instances rehabilitation on a minor scale maybe exempt from these requirements. An example of this work would be spraying an incipient weed infestation. If this is the case then the work will either be approved by using the Project Proposal Form discussed below or if it is conducted on tracks or related to other exploration activities the usual MRT exploration work approvals process will be used.
All projects will be circulated to Forestry Tasmania, Parks and Wildlife Service, Environment and Planning and Property Services at an early stage to determine their requirements and develop rehabilitation objectives.
Selection of sites and plans will be discussed with community and stakeholder groups early in the process to develop interest and support, assist in site selection, develop rehabilitation objectives and to avoid future conflicts.
Approval for work to commence on Crown Land
Crown Land Managed by the Parks and Wildlife Service (PWS)
Any works on land managed by the PWS has set procedures that must be followed before approval is given for work to commence. A Project Proposal Form (PPF) is required from any agency, organisation or person proposing to carry out works on public land (including PWS and DELM).
The PPF is an integral part of any rehabilitation project and must be factored in to the budgeting and planning process.
Information required for the PPF includes details of the type and scale of work proposed and prescriptions for the particular site. Natural resource information is also required.
The PPF is assessed by PWS staff from the different sections, i.e. Earth Science, Cultural Heritage, Threatened Species etc. It takes approximately five weeks.
Information assessed includes known natural and cultural values which may occur in the vicinity and how they may be influenced by on ground works. Consideration is also given to the prescriptions or treatments being proposed and whether they are consistent with conservation and land management requirements.
PWS staff are not available, unless adequately resourced, to do detailed environmental assessments outside the agency, it being the proponents responsibility to provide information necessary for an adequate assessment.
In some instances further on ground assessments may be required, if for example there is a high likelihood the works could impact on important conservation values or they may have adverse environmental impacts due to site conditions or the nature of the disturbance being treated.
Crown Land Managed by Forestry Tasmania (FT)
The great majority of identified abandoned mine sites occur on Crown land managed by PWS. In a situation where a site occurred on land administered by FT and major works was required a Level 1 permit would be applied for under LUPPA. FT would be consulted and involved in prior planning and approvals would need to be obtained through the relevant District Forester. In addition natural and cultural heritage considerations would be reported on to satisfy the Crowns responsibilities under the Threatened Species Protection Act, 1995 and Historic Cultural Heritage Act, 1995.
The Management Decision Classification System (MDCS) of FT will be a useful mechanism for identifying special values in areas prioritised for rehabilitation.
Appointment of Consultants
As MRT does not have the resources to project manage large rehabilitation works consultants will need to be appointed to manage these tasks.
To ensure fairness and transparency the best practice model advocated by the NSW Independent Commission Against Corruption (ICAC) will be used to select consultants.
By following the principles of probity set out by ICAC and the Association of Consulting Engineers Australia in the booklet 'Qualification Based Selection' the appointment of consultants will be seen to be ethical and maintain the integrity of the selection process.
Awarding of Tenders and/or Contracts
In most instances the appointed project managers will be responsible for the preparation and dissemination of works tenders.
MRT will approve the preferred tenderer after perusal of the applications and discussion with the project manager and the award of the tender will be ratified by the Trust Committee.
The project manager will use an Australian Standards approved tendering process such as the AS 4301 system.
After sites have been selected and prioritised, a project brief will be drawn up for work by Mineral Resources Tasmania and circulated to committee members. The agreed project brief will be the basis for invitation of tenders. This will include rehabilitation objectives, safety requirements, environmental management.
As work progresses, regular inspections will be made by Mineral Resources Tasmania staff in conjunction with the consultant and other members of the Trust Committee or representatives of the land manager as required.
The Trust Committee will meet quarterly. Progress reports on each individual project will be made quarterly and an annual report of Trust Fund activities will be produced.