An Innovative Approach to Designing an Environmental Risk Consequence Scale

Environmental risks are assessed for incident management, work planning purposes, environmental impact assessment, and project management.  While often required by regulations or other standards, environmental risk scales tend to involve subjective appraisal of different categories of effect.  The result is that identified levels of risk for a single event can vary depending on a user’s expertise, available background information, an opinion of effect magnitude, or other subjective aspects.  As a consequence, results are often debated among reviewers and the trust afforded an identified risk can be less than desirable.  To help resolve this dilemma, we reviewed risk assignment methodologies to benchmark criteria, and developed criteria ratings which followed risk management rules.  Using a set process for selecting criteria ratings, a number of subject matter experts from various environmental fields provided examples of environmental impact events and used the process to assign risk severities.  The resulting database was analysed to generate a decision tree which captured common pathways to deciding on a severity.   By using the tree, and following a severity pathway, users achieve a high degree of consistency in severity selections, with the background to a decision clearly identified.