SCARP, A TOOL FOR COLLECTION SYSTEM ASSET MANAGEMENT

Seattle Public Utilities (SPU) has embarked on an aggressive effort to more efficiently manage the maintenance and rehabilitation of Seattle's combined and sanitary sewer collection system. The Sewer Collection system Asset Rehabilitation Prioritization (SCARP) model has been developed to assist in this asset management effort. SCARP prioritizes defect repairs given budget constraints, selects between various rehabilitation measures as compared to point repairsof defects, helps establish repair and rehabilitation budget requirements given various measures of the condition of the collection system, and establishes effective inspection and maintenanceintervals for the sewer pipes. Alternative maintenance intervals and defect repair or elimination strategies are compared based on maximizing the net benefit to SPU, while adhering to operational, budget, and quality of service constraints. The model has been applied in two test cases containing subsections ofthe SPU collection system pipes. The results from both test cases indicated that SCARP could serve an important role in prioritizing defect repairs and rehabilitation projects.