A key tool for the asset management of stormwater pipes and facilities is the concept of Criticality which is closely linked to the Consequences of Failure.
High criticality assets have high consequences of failure and the management of such assets should be largely focused on avoiding failures through a range of pro-active monitoring, condition assessment, useful remaining life prediction and renewal processes. Contingency planning and risk reduction through measures such as duplication and may also be appropriate.
Conversely, low criticality assets have low consequences of failure and can largely be managed on a ‘fix when fail’ basis requiring relatively minimal management input.
Stormwater assets also need to be assessed in relation to their ‘Likelihood of Failure’ which largely reflects their life expectancy, and the extent of deterioration that has occurred. Assets that exhibit both high consequence, and high likelihood, of failure carry the highest risk of calamitous failure and should be the primary focus of stormwater asset managers.
Understanding which assets have an elevated criticality allows the organisation to focus resources on their care, condition monitoring and eventual renewal so that overall risk is managed to an acceptable level. Typically, there is a relatively small number of these high criticality assets and the process should be manageable.
This paper explores the concept of criticality for stormwater assets and its alignment with the typical corporate Risk Management Framework. It also outlines a robust approach for identifying which assets are critical and it illustrates the wide range of asset management approaches that should vary according to the criticality of the asset.
Also included is identification of a key difference between the stormwater service and water supply and wastewater services wherein assets in perfect condition can still be involved in calamitous failures if overwhelmed, i.e. differentiating between capacity failures and asset failures.