Developing a Practical Tool for Integrating Green Infrastructure into Cost-Effective Stormwater Management Plans
Type of DegreeMaster's Thesis
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Urban stormwater management today aims to manage both the quantity and quality of stormwater runoff. Best management practices (BMPs) such as detention basins have long been used to address runoff quantity objectives, and green infrastructure practices (GIPs) have emerged recently has an effective means for addressing water quality issues. There is a wide variety of GIPs available to stormwater designers, each with unique cost considerations and design guidelines. Optimal combinations of BMPs and GIPs can maximize stormwater benefits and cost effectiveness, but the available tools for BMP optimization are designed to be used by experienced stormwater practitioners. A simplified tool designed for inexperienced practitioners is needed to promote widespread use of green infrastructure. A spreadsheet-based decision-support tool was developed to equip designers with a means to develop cost-effective stormwater management plans that integrate GIPs with other stormwater BMPs. The tool was designed to be flexible and easy-to-use while still providing actionable stormwater designs and cost estimates. The tool allows the user to select intrinsic and structural GIPs to achieve a target runoff reduction for water quality objectives. The hydrologic impact of using green infrastructure is modeled and measured with rainfall-runoff simulations. An optimization model for a detention basin BMP was developed to be used in conjunction with the spreadsheet tool. The tool was applied to a representative case study site for which the actual design and cost estimates of on-site BMPs were known. The tool provided realistic results for the case study analysis and revealed that successive applications of the tool could easily provide the user with a site design that maximized cost-effectiveness. A major benefit of the tool was that application of the tool required little time or effort on the part of the user and use of the tool required no specialized computing or stormwater modeling expertise. A sensitivity analysis of the tool illustrated the critical trade-off relationship between GIP costs and detention basin BMP costs and identified the potential for improving local stormwater policies.