“Keep it Cool”: Implementing GSI, in the Transportation Corridor, to Reduce Urban Heat Islands

Abstract Submission: High heat in urban areas strains energy infrastructure and negatively impacts human health with long term and even fatal consequences. When high heat occurs in socially vulnerable areas, it can result in increased energy costs for low-income residents and exacerbate existing health inequities. Unfortunately, determinants of high heat—concentrated impervious surfaces and a lack of trees and vegetation—also contribute to poor stormwater management, particularly in low-lying areas and in the transportation corridor. Therefore, the implementation of green stormwater infrastructure (GSI), specifically practices that include vegetation and trees, in the right-of-way can provide mutual benefits for urban heat island (UHI) mitigation, water quality, and climate resilience.
In 2022, the Raleigh City Council awarded Raleigh Stormwater an allocation from the city’s ARPA funds to identify locations in neighborhoods disproportionately impacted by the COVID-19 pandemic where GSI may mitigate UHI effects. Tetra Tech was contracted to select, design, and oversee construction of the GSI practices.
Potential parcels and right-of-way segments were scored based on indicators of urban heat, suitability for GSI, and other factors related to the project’s potential benefits. The top sites were screened and further refined into a list of six recommended locations. Of those, three moved into design, and two advanced to final design. Notable observations were the identification of affordable housing communities as well-suited locations for GSI, the challenges created by ongoing redevelopment in a growing city, and the limitations of working within grant-mandated timelines. Design enhancements, including suspended pavement, were incorporated to maximize potential storage in ultra urban areas.

Learning Objectives/Expected Outcome (Optional) : Following this presentation, attendees will be equipped to describe how GSI mitigates UHI, identify factors that may be used to select sites that benefit both water quality and UHI, and resolve potential obstacles in GSI implementation.