Environmental impacts of stormwater bioretention systems with various design and construction components

Abstract

Nature-based blue-green infrastructure for urban stormwater management, such as bioretention systems, is considered to provide multiple benefits compared with conventional stormwater runoff quantity and quality control. There are a range of bioretention systems and design and construction can vary widely. Studies comparing environmental impacts between different stormwater bioretention systems with various design elements and construction components have been lacking and hence, this study aims to address this gap. Various designs of stormwater bioretention systems with differing construction components and filter media mixtures have for the first time been compared using a life cycle assessment approach. Environmental impacts related to the production, transportation, and installation phases (i.e. before operation) of four types of bioretention systems, encompassing 11 configurations, have been assessed. The various construction components and filter media mixtures used incur differing degrees of environmental impacts. The filter media mixtures requiring longer transportation distances were associated with the highest environmental impacts. In this analysis, the bioretention systems built with more kerb stone, without geotextile and a filter media with sand, soil and gravel incurred the lowest environmental impacts. Whereas the bioretention systems constructed with the most concrete and with filter media that included pumice incurred the highest environmental impacts in all categories, up to 9–24 times greater than the systems with less concrete and no pumice. When means of transportation and distances were considered further in the sensitivity analysis, the concrete intensive structures incurred the highest environmental impacts. These findings can improve design choices and selection of construction components for stormwater bioretention systems where environmental impacts are considered important. • Comparing various blue green infrastructure bioretention designs with LCA approach. • Construction components used in bioretention systems incur environmental impacts. • Differing design elements and types of system incur different impacts. • The greatest environmental impacts are associated with the use of concrete and pumice. • The material transportation phase accounts for the largest environmental impacts.