Strategic Asset Management Modeling Project: A Change in Thinking about Life

摘要

Anchorage Water and Wastewater Utility's (the Utility) historic Strategic Asset Management Modeling efforts have been predicated upon maintaining current service levels and based on life estimates derived from industry and depreciation life. In order to better illustrate the relationship between operational and capital expenditures and level of service, the Utility reassessed the tolerance for failure for water pipes based on consequence of failure for each pipe. This tolerance for failure was then used to determine the estimated pipe life based on derived pipe failure curves. The major shift in modeling as compared to the Utility's previous modeling came from a very simple yet powerful change in the understanding of real world pipe situations: it is acceptable for pipes to break as long as the Utility has the maintenance capacity to repair the pipe in a reasonable timeframe and service levels are maintained. While this has always been understood, it hasn't appeared to have been built into many models. By assessing the consequence of failure for each pipe segment, the Utility was able to assess which pipe segments had greater impact on service levels in the event of a break, either through supply issues (e.g. transmission mains), service interruption (e.g. hospitals), or the duration/cost of repair (e.g. deep bury pipe). By evaluating service life based on consequence of failure, the Utility was able to model the impact the shifts in budgeting have on future levels of service. As a result of this change, the Utility was able to re-allocate and reduce capital replacement needs funding by significant amounts (20% per annum), with minimal expected service level impacts while also planning for increased Operation & Maintenance funding to reflect the increased tolerance for low-impact failures.