Advancing Benefits and Co-Benefits Quantification and Monetization for Green Stormwater Infrastructure: An Interactive Guidebook for Comparison Case Studies

As the world faces increasing community challenges associated with climate change and water quality standards, the role and importance of green stormwater infrastructure (GSI) is expanding. Quantifying and monetizing the benefits attributable to GSI is imperative for the evaluation of future stormwater investments. A triple bottom line (TBL) cost-benefit analysis quantifies and monetizes the costs and benefits of employing alternatives with a focus on financial, social, and environmental outcomes. This approach ensures that holistic costs and benefits of each alternative are presented to the decision makers, and ultimately allows for better and more complete decisions to be made with limited resources.

This project benefits utilities and municipalities of all sizes by (1) developing a user-friendly guidebook with case studies at a variety of scales and geographies to advance the quantification and monetization of benefits and co-benefits of GSI at the community level; and (2) advancing the practice of benefits and co-benefits quantification by identifying and prioritizing the research needs among GSI benefit and co-benefit categories. Six case studies of varying scales, geographies, and storm sewer typologies were selected and run through CLASIC and the GSI TBL Tool to compare the outputs of each tool. This report summarizes model inputs and outputs, and recommendations for future research. Published in 2023.