Predicting the carbon footprint of urban stormwater infrastructure

Abstract

Due to increased regulations concerning urban stormwater runoff, stormwater control measures (SCMs) such as bioretention, ponds, and constructed stormwater wetlands, are becoming a more common feature of urban and periurban landscapes. The water quality and hydrologic benefits of SCMs are generally well-documented, and planning tools are available to optimize water quality benefits with economic costs of SCM construction and maintenance. Given rising interest in and potential for regulation of carbon emissions, a planning tool that allows for estimation of carbon emissions associated with SCM construction and maintenance is also a relevant pursuit. The objective of this work was to present a framework by which carbon emissions attributable to SCMs and conveyances could be predicted. This method was then applied to present a comparison of the carbon footprint of eight common SCMs and three stormwater conveyance types. The carbon embodied in construction materials represented a prominent part of the carbon footprint for green roofs, permeable pavement, sand filters, rainwater harvesting systems, and reinforced concrete pipes while material transport and construction dominated that of bioretention systems, ponds, wetlands, level spreader-grassed filter strips and concrete-lined swales. Despite accounting for sequestration by vegetation in these systems, only stormwater wetlands and grassed swales were predicted to store more carbon than what was released through construction and maintenance.