LONG-RANGE WASTEWATER COLLECTION SYSTEM PLANNING IN AN ASSET MANAGEMENT FRAMEWORK

In 2004, Seattle Public Utilities (SPU) and its consultant, Brown & Caldwell (BC) began work on the SPU 2006 Wastewater Systems Plan to guide the management of SPU's wastewater collection and conveyance system for the next 20 years. The plan was developed within SPU's asset management framework. Asset management tools and principles were applied to (1) establish service levels, such as a the frequency of sewer backups, considering both costs and benefits; (2) identify the most cost-effective strategy for reducing sewer backups; and (3) determine the optimum level ofsewer rehabilitation funding. Whereas previous operations and maintenance (O&M) and capital practices were defined by past experience or available funding, the programs proposed by the 2006 Wastewater Systems Plan were selected because they achieve cost-effective service levels at the lowest life-cycle cost while managing risks to both the utility and its customers. The process demonstrated that application of asset management principles in long-range wastewater planning can enable utilities to make defensible decisions which ultimately lower the costs of services for the utility and its rate-payers.