Poster Presentation
ALARP (As Low as Reasonably Practicable) is featured in several state-of-the-art guidelines, such as the Canadian Dam Association (CDA), the Mining Association of Canada (MAC), and the Australian National Committee on Large Dams (ANCOLD), as well as in GISTM/ICMM which all address risk evaluation and recommend the use of ALARP. In some literature ALARP is essentially represented as the trade-off equilibrium between mitigation costs and risk reduction benefits. However, its most modern definition is that a residual risk, i.e. the risk after mitigation, shall be as low as reasonably practicable and to be considered ALARP it must be possible to demonstrate that the cost involved in reducing it further would be grossly disproportionate to the benefit gained.
Being able to demonstrate ALARP status, that is locating the minimum ALARP point (LMALARP) is therefore paramount to owners, Engineer of Record (EoR), the public, insurers, lenders and regulators.
Rationally LMALARP yields better decisions, enhances value of projects and avoids mitigative Capital Expenditure (CAPEX) squandering. LMALARP should not be seen as a static process, as it has to encompass various time horizons along the life of a project/facility. Indeed, the short term ALARP may be very different from the long term one due to different uncertainties, changing system conditions and external evolution, such as for example land use around the considered facility which will require adaptation.
This paper showcases how to quantitatively incorporate lifespan in the ALARP assessment when looking at a specific mitigation program and/or to compare different mitigation options.
To do so, annualized quantitative risks have to be evaluated for each mitigative alternative, and the cost of the various mitigative actions estimated. For each time horizon the result is the trade-off equilibrium between mitigation costs and risk reduction benefits which represents the minimum theoretical ALARP point. Various considerations can then guide the decision-makers to select the point where the cost involved in reducing it further would be grossly disproportionate to the benefit gained.
This process has been applied to existing facilities, which showed how the optimum solution varies, not only when the weighting of the different consequences is shifted (environmental vs financial vs reputation, etc), but also when the lifespan of the structured is considered.
Authors
Ignacio Cueto, Senior Geotechnical Engineer | SRK Vancouver
Osvaldo Ledesma, Principal Geotechnical Engineer | SRK Vancouver
Franco Oboni, Corporate Risk Consultant | SRK Vancouver
Click here to view all presentations at this event.
