How short-term decisions have lasting geotechnical impacts on mine sites

It’s no secret things don’t always go to plan on mine sites. Between unexpected ground conditions, delayed approvals and pressure to meet targets, it’s reasonably common for last-minute decisions to be made about where to mine, with the outcomes not always matching the long-term geotechnical plan for a site.

The problem with this approach is that short-term decisions can have long-lasting implications on a mine site, resulting in increased costs, inefficient dig areas, and the creation of new geotechnical hazards, pit wall instability or sub-optimal layouts.

While a geotechnical engineer can usually find a way to mitigate hazards, the controls they can put in place to make the space safe become quite limited. Bespoke short-term designs are typically more aggressive and may not satisfy all the design criteria guidelines adopted for mid or long-term pit design.

For instance, an unplanned decision not to pre-split a wall can create a new rock fall risk. If this happens outside of the existing geotechnical design, the hazard controls that can be used to reduce that risk are limited to engineering or administrative controls. Usually this means geotechnical engineers must implement larger stand-off zones around hazards, which creates smaller, less efficient work areas.

The more frequently these short-term decisions occur, the more inefficient a mine becomes. After a while, the knock-on effects of inefficient dig areas, multiple controls and vulnerabilities, means miners are constantly forced to working around hazards. Unfortunately, when a pit reaches this point, it can become costly and time consuming to get things back on track.

In an ideal world, every mine site would be perfectly designed and adhere to the carefully created plan. But in reality, priorities change, new data is uncovered about the site, and quick alterations to plans need to be made. It’s important to note that short-term strategic planning is not the issue. It is the failure to consider all the aspects and the future implications of a decision that is the problem.

Working closely with a geotechnical engineer can help you calculate the impact of a short-term decision and uncover exactly what that move will mean for the site in the long term.

A good geotechnical engineer will take a double-pronged approach to their short-term strategic designs, both supporting the mine schedule while providing safe conditions and minimising geotechnical risks for people and equipment.

This means short-term plans implemented should not sacrifice the long-term pit schedule. For example, if a wall needs to be buttressed, the buttress must not cause access to other ore to become unprofitable. Or if ore recovery is going to cause a wall failure, consideration needs to be given to whether that failure will impact the long-term pit schedule.

Clear communication throughout this process is vital. A good geotechnical engineer will work with the key stakeholders that need to be consulted and balance out the different requirements. While some stakeholders may need to compromise on their requirements more than others, they should still be identified and considered to influence the design outcome positively and work towards the goal of ensuring production and shipments are not delayed.

If you would like to learn more about how a geotechnical engineer can support your site, please contact us.