AAOM Handbook

threats must be identified based on a detailed understanding and analysis of the relevant threat mechanisms and initiators.

There are six basic options (Service Strategies) for managing threats. These options can be arranged in a hierarchy of desirability where the highest option in the hierarchy that is both feasible and has lower cost (both direct implementation costs and the lost opportunity cost that arises from implementation of the strategy) is the preferred choice for the process. The options in this hierarchy are: • Modification of the process – implement design changes in order to reduce the threat consequence, probability or exposure. This type of strategy may be applicable where there are alternative designs, materials or methods. Implementation of this strategy requires a single change action, and will typically also either remove or reduce the need for further Service work. However, where any probability of the threat remains, one of the remaining Service Strategies will be required to deal with the residual threat. In an underground mining process this strategy could be the use of 'shot-crete' ground support in lieu of rock-bolts, hence reducing the risk of injury from falling material and removing the need to scale the walls and ceilings of workplaces. In a mineral processing plant this could be to change the design of a material feed chute to remove or reduce the occurrence of blockages and the need to clear them. In a safety context this might be the application of mechanical lifting aides to remove/reduce the risk of physical injury caused by lifting heavy items. • Monitor process condition and/or performance to identify the development of a threat, and hence determine the best timing and type of Service action to deal with the developing threat. This type of strategy may be appropriate where there is considerable variability in either the onset of threat development or in the rate at which a threat escalates, and there is a detectable indication of the developing threat condition that provides sufficient warning for an effective control action to be taken. Implementation of this strategy requires a primary action to regularly monitor the threat indication, and when the indication exceeds an acceptable level (defined by measureable condition or performance parameters), a secondary action to manage the threat. In an underground mining process this could be the monitoring of erosion in an ore pass in order to determine if reconditioning is required. In a mineral processing plant this could be to monitor pressure drop across a filter in order to determine when the filter is blocking and hence when to clean or change the filter media. In a safety context this might be the use of task observations to determine when re-training of personnel in safe work methods is required, or the use of a hazard assessment process prior to the commencement of a task. • Initiate Service actions based on a pre-defined interval or life - usage based. This type of strategy may be appropriate where the probability of a threat is initially very low, but shows a rapid increase after a relatively consistent time or service interval. Implementation of this strategy relies on measuring a proxy for the probability of threat development (typically