Developing a Practical Tool for Integrating Green Infrastructure into Cost-Effective Stormwater Management Plans

Green infrastructure (GI) practices are an effective means for improving the sustainability of stormwater management. Optimized combinations of GI practices with other management practices, such as detention basins, can maximize performance and cost effectiveness, and simple methods for identifying these combinations will promote more widespread use of GI. We created a spreadsheet-based decision-support tool to help designers to develop cost-effective stormwater management plans that integrate GI practices with detention basins. The hydrologic impact on detention storage of using GI practices is modeled with rainfall-runoff simulations. An optimization model for a detention basin was developed to be used in conjunction with the spreadsheet tool. We applied the tool to a representative case study site for which the actual design and cost estimates of stormwater infrastructure were known. The tool provided realistic results and the case study revealed that successive applications of the tool could easily provide the user with a site design that improved cost-effectiveness. A sensitivity analysis illustrated the critical trade-off relationship between GI costs and detention basin costs. (C) 2021 American Society of Civil Engineers.