This risk is very relevant, even when operations are not nearing closure. Reworking previously rehabilitated areas, difficulties seeking project extensions and poor relations with regulators and communities can result from a badly followed process of closure planning prior to closure.

Insufficient or inappropriate closure planning preparation can also lead to increased operational costs and a potential regulatory burden, including performance bonds.

There are seven key areas in which these planning shortfalls may lead to difficulties achieving successful mine closure.

Firstly, a lack of pertinent baseline and monitoring data obstructs good closure planning from the outset, resulting in a failure to understand key closure risks and drivers at a site. Collecting good baseline data to demonstrate original site conditions pays for itself quickly, enabling acceptable and achievable closure goals to be developed with stakeholders. Rehabilitation trials such as well-monitored progressive rehabilitation are a practical strategy to address this issue.

A second critical omission is insufficient understanding of mine wastes. Mine waste remains on the site, in perpetuity, while the ore is sent to the customer. Waste material characteristics and volumes are important if the three “r’s” – having to re-drill, re-characterise and re-handle waste – are to be avoided. Simply establishing and maintaining good waste management records is an easy solution that most of the big miners already practice well.

A third significant issue can often follow if poor waste management leads to contact between geochemically-enriched waste and initially clean site water. If water quality such as acid and metalliferous drainage (AMD) is allowed to develop, this then liberates more acidity in much the same way as a fire, once started, produces more flame.

AMD is arguably the single biggest curse on successful mine closure planning and is frequently the single biggest management issue post-closure. Mine waters present an often-insidious side of mine closure that may tarnish a social licence to mine for millennia if adequate provision is not made for sustainable long-term management.

Failure to engage stakeholders in an early structured and documented process is a fourth failing, often resulting from the fifth and general issue of planning procrastination. Failure to engage stakeholders often arises from thinking mine closure is an activity at end of life of mine, rather than as a process that begins with the initial mine plan and continues throughout mine life; a continuous journey to the final destination.

Diligent, regular planning assessment and stakeholder consultation from an early operational phase may fend off later criticisms, lead to closure outcomes better directed by years of underpinning work and so reduce end-of-mine costs. Good stakeholder engagement practice can often be simply described as engaging early, engaging often, and engaging honestly and transparently.

A sixth significant closure issue is the failure to account for the long-time scales that closure planning must accommodate, particularly so when costing closure. Operational design considerations have much shorter timespans than their closure equivalents; standards are therefore higher for closure landforms than for their more temporary operational counterparts. Considering the closure plan and final site layout at all times during operation can avoid expensive redesign and reconstruction costs during life of mine.

A seventh issue often causing plans to fail regulatory approval is not having a clear objective and approach to closure outcomes. This may result in a focus on technical studies that fail to provide better closure understanding and insufficient attention on developing a final land use in concert with key stakeholders, which is ultimately what mine closure is trying to achieve.

Driving closure planning by well-defined goals through tools such as corporate closure standards designed to meet both internal requirements and relevant closure guidelines is an ideal solution that many companies now use to direct efforts from exploration throughout life of mine.

Avoiding is better than undoing planning mistakes.

Industry case studies worldwide have repeatedly shown that remedying closure liabilities is more expensive, unpredictable and takes longer to achieve. Proactive operational management of risk with a view to avoiding these liabilities in the first instance is much more reliable and cost-effective.

While avoidance of these key closure problems is no guarantee of successful relinquishment, recognition of these issues and judicious planning to overcome them is more likely to present well-considered closure plans.

Ultimately, closure planning can best be described as a “land redevelopment” exercise. Although the focus of mine closure is typically on constructing final landforms through geotechnical and other civil engineering approaches, the end result of all efforts will be determined by how well they meet their pre-defined social and environmental values.

The focus should therefore be on understanding the changing social and environmental context, having a clear closure objective to work towards, and on identifying how operational constraints, decisions and trade-offs will impinge on post-closure liability.

Dr Clint McCullough is a principal environmental scientist at Golder Associates and a principal of the Mine Water and Environment Research Centre (MiWER). He can be contacted on (08) 9213 7600, or by emailing cmcullough@golder.com.au