Managing geotechnical risk on complex mine sites

People are creatures of habit. We park in the same spot at the shopping centre, holiday in the same places and like to do things the way we have always done them. This tendency towards habit can be a dangerous default in a dynamic mine environment, where a focus on monitoring and managing geotechnical risk is key.  

Mines, like people, are prone to developing behaviours and practices that become routine overtime. These processes can become entrenched based on prevailing conditions, which are usually uncomplicated at first. Most mines are not geotechnically complex at the outset but become more so as operations progress.  

The danger is that a mine site used to operating in favourable conditions can become complacent, losing focus on ensuring the geotechnical model reflects current ground conditions: structural geology, groundwater and rock mass strength. Deficiencies in any of these measures means the geotechnical model will not properly reflect in-situ conditions. So, the mine is operating to the expected, rather than the actual, environment. 

When more complex, unfavourable conditions are encountered, failures can occur. Good practices are lost, poor decisions are made and shortcuts are taken to increase efficiency and achieve the mine plan in the short-term. This can create a cascade of errors until a significant geotechnical event occurs, such as a slope failure or collapse, resulting in a major financial impact, or worse, a fatality. 

In the wake of any major event, there is suddenly a laser focus on the geotechnics department. But cure always comes at a greater cost than prevention. 

The geotechnical model for the mine may need to be re-developed and tested using more sophisticated (and expensive) systems to accurately reflect the rock mass behaviour and prevailing conditions. 

Enacting plans for pit remediation can be a years-long process. For example, because metals are mined using a cutback system to funnel down to a target zone, the design is effectively set once the cutback is started. Therefore, remediation after a geotechnical event can require the mine to be reset to manage the threat in the short term, then re-designed to eliminate the risk. 

This incurs enormous costs, not to mention the lost productivity of labour hours spent managing and mitigating geotechnical risk rather than focusing on extraction. 

Alongside these on-ground remediation measures, a significant investment is needed in the `human factor’. You can’t change the pit without changing the people. 

So, running parallel to geotechnical plans, there should be a review of the site practices and management, with the aim of developing a robust change-management process that will guard against future lapses.  

A central plank of this is ensuring everyone understands their actions play an important role in supporting the geotechnical performance on a site. This includes things such as surface water management, good drill and blast practices, accurate modelling and data capture, and investment in drilling and wall scaling. Geotechnical plans hinge on solid data and compliance. 

Management also needs to commit time and resources to explaining the situation. Operators need to know: what is changing and why; what remediation measures are necessary; what role they play in it; why it is important; and what the outcomes will be. 

Maintaining a focus on sharing outcomes as the plan progresses helps create a positive feedback loop, where people see the progress the mine is making because they have implemented change.  

Seeing the mine move forward and solve a problem – even if it spans years – helps reinforce behaviour change towards a safer, more productive mine.