Implications of transitioning to green infrastructure: a quantitative sustainability assessment of stormwater management
The implementation of green infrastructure as a means to reduce stormwater through infiltration, evapotranspiration, and reuse is occurring in municipalities to reduce wastewater treatment loads (in the case of combined sewer systems) and pollution of surface water. Although green infrastructure technologies are becoming increasingly common and are propounded as being universally more sustainable than grey infrastructure, the economic and environmental implications of transitioning to green infrastructure are unique to each municipality and project. Many sustainability assessments have been reported in the literature comparing green and grey infrastructure, but what is lacking is a fundamental understanding of how design and operational decisions influence the sustainability of a community and its drainage infrastructure. This work elucidates sustainability implications of design decisions, including costs and indirect impacts of green and grey infrastructure, in order to inform urban stormwater management decision-making in the city of Chicago. An environmental assessment using life cycle assessment methodology, construction and design data, as well as data from the literature concluded that concrete production used during green infrastructure retrofits contributed 89.3-99.6% of the life cycle environmental impacts. While the studied green infrastructure retrofit introduced 4.35x107 kg CO2 equivalents to global warming and had many other environmental impacts, a comparable street rejuvenation project relying on grey infrastructure contributed approximately 20 times the environmental impacts across all environmental impact categories. Further, an economic analysis quantifies the cost of implementation for this project to be between US1.4−3million whereas the cost of a traditional street renewal project for the same system boundary is estimated to be US 520,000. Also, the cost of treatment using green infrastructure was found to be four orders of magnitude greater than treatment at a wastewater treatment plant (WWTP). Finally, based on public records and by drawing from related studies in the literature, implementing green infrastructure had the indirect benefit of adding value to surrounding properties. By quantifying environmental, economic, and social impacts, a triple bottom line assessment was completed for Chicago’s stormwater management options to help navigate tradeoffs across and within dimensions of sustainability.
green infrastructure, life cycle assessment (LCA), sustainability
University of Illinois - Urbana-Champaign
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University of Illinois at Urbana-Champaign