Life-Cycle Costing For Distributed Stormwater Control Measures On The Gray-Green Continuum: A Planning-Level Tool

Managing stormwater is an important element of sustainable water management. Access to multiple types of stormwater control measures (SCMs) along the gray-green continuum presents decision makers with flexibility in managing stormwater. Greener SCMs offer potential benefits like longer-term water retention, runoff reductions, and pollution reduction. Lack of access to context-specific life-cycle costs, however, particularly for less conventional SCMs, poses challenges for planners. To address this challenge, this paper presents a new Excel-based life-cycle cost tool that enables planners to evaluate internally consistent US cost profiles for suites of SCMs using process-based quantity estimation covering materials, labor, equipment, energy, and environmental costs. The module includes 16 classes of distributed SCMs on the gray-green continuum, which can be assessed individually or in groups. The tool is preloaded with dynamic defaults but is designed to be highly customizable and includes built-in scenario analyses. Integration with the overall Integrated Decision Support Tool (i-DST) enables performance-based analysis. This paper describes the tool and presents example analyses. (C) 2020 American Society of Civil Engineers.