Risk Assessment and Management Using Layers of Protection Analysis and Bowties
Paul M. Bedell, M.E.Sc., P.Eng. - Principal Senior Geotechnical Engineer at Golder Associates
Paul is a geotechnical engineer with over 22 years of experience in mine waste management. He is a Principal of Golder Associates Ltd., where he has spent his entire career, and is based in Vancouver.
He has worked on projects across North America, including the high Arctic, Mexico, South America, Africa, and Mongolia. He is an engineering manager for various mine waste management projects, provides support to operations, acts as the engineer of record on several sites, and is professionally registered in BC, ON, SK, and NT/NU.
Paul earned his BESc and MESc degrees from The University of Western Ontario.
The presentation will describe the use of a “layers of protection analysis” (LOPA) for a risk assessment for the design and operation of tailings dams. Presented using a bowtie diagram, the LOPA is considered to improve upon the more typical risk assessment approach of using unmitigated and mitigated risk heat maps.
High consequence / low likelihood risks are difficult to effectively communicate and manage by simple risk assessment tools like a heat map; tailings dam failures fall into this category.
The focus, therefore, needs to be on the controls—the barriers—and not the risk ranking. The identification of independent controls that are effective in preventing the consequence are useful in design, review, and operations. The auditability of the barriers and their reliability are significant strengths to this approach and aid in decisions regarding the adequacy (type and number) of barriers.
The bowtie analysis and presentation style allow for ease of clear and complete communication and may be readily linked to management systems and documentation whilst also being of critical importance in design, review, operations, and audits. An example case study will presented and discussed.