Mine Closure in Western Australia

Anyone looking to prospect, explore or extract minerals in Western Australia must submit a mining proposal that describes how they will identify, evaluate and manage the environmental impacts of their proposal. This approvals process is overseen by the Department of Mines, Industry Regulation & Safety (DMIRS) and the Environmental Protection Authority (EPA).

All proposals need to include a Mine Closure Plan (MCP), detailing how the proponent plans to prevent or minimize adverse long-term environmental, physical, social and economic impacts, and ultimately, create a stable landform.

To be approved, a Mine Closure Plan must:

• Describe the post-mining land use, which has been determined in consultation with key stakeholders;
• Be achievable given the capacities of the land after mining; and
• Be ecologically sustainable

The best outcomes for the miner, the environment and the community are achieved when mine closure planning is integrated with a site’s operations from the earliest phases of a mine’s life. This approach minimizes material re-handling, decreases long-term water collection and treatment costs, creates opportunities to accelerate the operational schedule, and decreases capital costs by leveraging equipment already available onsite.

This also helps avoid closure plans being misaligned with operational plans, helps identify opportunities for progressive reclamation, and reduces post-closure liability. For these reasons, DMIRS requires an updated Mine Closure Plan to be submitted every three years until relinquishment.

Importance of Environmental Data

To inform the Mine Closure Plan, Iimit uncertainty and reduce the risk of long-term impact, environmental data should be collected and expanded throughout the life of the mine. This includes data from research, field trials and investigations.

Comprehensive characterization of materials (including soils and mine waste) is critical to effective closure planning and successful progressive rehabilitation. Characterization of materials allows for separation and selective placement of materials considered beneficial to rehabilitation and segregation of materials that may inhibit rehabilitation or cause detrimental effects.

The Mining Rehabilitation Fund and Progressive Rehabilitation

Each year, miners are required to determine their rehabilitation liability estimate and contribute 1% of this cost to an annual non-refundable levy known as the Mining Rehabilitation Fund, or MRF. The levy is based on the area of land disturbed, the level of disturbance, and the amount of rehabilitation that has already taken place.

The funds raised from this levy are paid into a pooled fund held by the WA State Government and used for rehabilitation in the event a mine operator is unable to meet its rehabilitation commitments, usually because of insolvency. Interest earned on the fund contributes to the rehabilitation of legacy mines, research into mine rehabilitation, and the administration of the MRF.

Changes to DMIRS’ process in 2021 have made it possible for WA mining operations to rehabilitate parts of a site during their operations. If closure criteria have been achieved for specific landforms such as mine rock stockpiles and open-cut pits, for example, they can now be removed from an operation’s liabilities, thereby reducing the annual MRF levy that must be paid in subsequent years.

How Okane Can Help

Okane’s geologists and engineers develop and manage comprehensive material sampling and laboratory testing plans to understand potential geochemical, geotechnical, and geomorphological risk, and develop site-specific mitigation and rehabilitation plans.

Because of its potential impact on the surrounding environment, mining operations should have a management plan for acid and metalliferous drainage (AMD) in place as early as possible in the mining lifecycle.

Okane’s team of geochemists, geologists and engineers can integrate geochemical, geological, and geophysical information, with site-specific climate and environmental factors and develop customized, site-wide AMD/ARD management plans for your operation.

Our Advanced Customizable Leach Columns, or ACLCs, were developed as a method for completing customized kinetic geochemical testing of waste rock and other mine site materials, and we have been gathering evidence that they better replicate site conditions in a laboratory setting when compared to standard tests.

Within the columns, matric suction potential, volumetric water content, airflow, and gas composition are controlled and monitored continuously, allowing interpretation of the kinetic geochemistry with respect to the physical setting and with fewer scale-up assumptions.

Here’s a paper and  a 1-minute video about our ACLCs.

Okane has scientists and engineers based in Perth, backed by a global team in Queensland, New Zealand, Canada and the USA.

If you need assistance with developing, updating and implementing an integrated Mine Closure Plan, undertaking progressive rehabilitation, or any aspect of mine closure for a mining operation in Western Australia, reach out to us at www.okaneconsultants.com/contact-us/.

Useful Links:

DMIRS Mine Closure Plan Online Portal

www.dmp.wa.gov.au/Environment/Mine-Closure-Plan-6034.aspx

DMIRS Website — What is the MRF?:

www.dmp.wa.gov.au/Environment/What-is-the-MRF-19522.aspx

Mining Rehabilitation Fund (MRF): vimeo.com/120759523

References

DMIRS, 2021. Mine Closure Completion Guideline. https://www.dmp.wa.gov.au/Documents/Environment/REC-EC-237D.pdf