Investor confidence is largely driven by a mining company's ability to deliver on the guaranteed return on investment. Thus, robust due diligence processes, functioning as part of a mining company's corporate governance, become essential tools to identify hazards that can impact production, assess the associated risks and introduce controls to manage the risks. The geotechnical practitioner is tasked to manage one of the biggest risks on the mine; that of a rock mass instability. Since an instability, or collapse, need not be large to have a significant impact on production, the challenge is to develop an optimised life-of-mine design with a risk management plan that suits the risk requirements of the mining company and investors, whilst meeting acceptable, minimum safety standards. The concept of a Geotechnical Review Board has been adopted in the industry as a vehicle to provide assurance that the geotechnical risks on a mine have been identified and are being properly managed. The review relies on external parties providing appraisals of the design and processes, and experienced oversight of the active operations. In general, these reviews tend to have a unique style; often a combination of the current, visible, critical issues on the mine and issues deemed as important by either the reviewer or a third party. Coupled with the challenge of fluidity in modern planning environments, the geotechnical practitioner is often still faced with uncertainty in the level of geotechnical risk associated with any given mine plan. This paper introduces a geotechnical risk assessment tool that has been developed for use as a leading indicator within AngloGold Ashanti's international operations. The authors aim to provide the reader with insight into how the tool can be utilised to understand a mine's ability to proactively identify and manage geotechnical hazards, by exploring the following components: Introduction to a questionnaire, which is the main input, and serves as a means for the practitioner to assess the geotechnical engineering activities being conducted on the mine compared to best-practice in the industry. Using a qualitative geotechnical risk matrix to report the status of the primary hazard control classes and the overall geotechnical risk on the mine compared to others in the company. Establishing a reliability index for the geotechnical engineering system (GES) on a mine, which can be used to illustrate how the mine's GES compares to that of a project (ranging from conceptual to feasibility level), design and construction phase, operational phase, and industry best-practice.

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Slope stability acceptance criteria is often applied from standard tables representing industry practice or corporate risk tolerance. While in many cases such standard off-the-shelf solutions are fit for purpose, in the case of slopes with a high value increase per incremental slope angle increase, or where high-cost infrastructure or other sensitive locations are nearby, it pays to have a custom Probability of Failure acceptance criteria determined through risk analysis. The value lies in being able to quantify the consequences of hazards that are slope angle driven, and in determining the mining schedule consequences of these hazards through Probability of Failure. This paper demonstrates the concept of the risk-based geotechnical assessment through a practical example of a small saprolite pit in West Africa, how such an analysis was carried out, and how the cost-appropriate risk controls were put in place. The example is based on a gold mine, and considers the timing and size of potential failure as well as the mining schedule and cash flow schedule. The type and size of appropriate risk controls are also estimated in the calculation. Finally, the paper demonstrates through the model how the value of geotechnical engineering controls can be calculated using the concept of real options.

Many publications are available that provide statements of best practice in terms of open pit slope risk management. However, to date none provide a risk model that demonstrates the risk reduction achieved for applying each of the risk management elements. This leaves the slope stability practitioner unable to analytically answer questions such as:  How frequently should slopes be inspected?  How frequently should prisms be read?  Should a radar be acquired? If so, which one?  How many monitoring systems to use? And many more. This paper applies the Venter and Hamman (2018a) temporal safety risk model to an open pit in West Africa. The paper demonstrates the use of the model to a small saprolite open pit and concludes with recommendations for slope instability registers to facilitate future back-analysis in terms of this model.