RISK -BASED MODEL/DECISION SUPPORT TOOL FOR WASTEWATER ASSET REFURBISHMENT AND REPLACEMENT (R&R) PLANNING

Utility best management practice, as embodied in asset management terms, is delivering to customers defined levels of service at an acceptable risk at the least life-cycle cost of asset ownership. The challenge for utility mangers is defining ‘what is the lowest cost of asset ownership’ when considering the balance of operational, maintenance, refurbishment, and replacement costs all within an acceptable risk framework. This paper addresses development of a decision support tool to assist utility managers in optimizing decisions related to asset refurbishment and replacement (R&R). Key R&R decisions for utility managers include, “When do I intervene? What is the intervention? Should I intervene? How much should I include in my budget near term and long term? and How do I present the information to sustain R&R funding against the competing interests for my utility's limited capital dollars” This decision support tool identifies the optimized timing for a specific R&R intervention by balancing the cost from increasing risk of failure as an asset ages against the benefit of delaying R&R capital expenditures. The output of the tool is an optimized and justified timing strategy for asset rehabilitation, expressed in benefit/cost ratio terms, and a long-term forecast of future R&R investments as necessary to support sustaining a utilities infrastructure. This tool has been used by several utilities to support their R&R programs for wastewater collection pipe networks, pumping stations, flow control structures, and wastewater treatment plants.