Sustainable Management of Urban Runoff Using Novel Engineered Soil Media in Bioretention Systems: A Lifecyle Assessment

This study explores the use of water treatment residuals (WTR) and construction waste (CW) in bioretention systems (BRS) for managing stormwater in urban areas. Using life cycle assessment and cost analysis, we compared the performance of an engineered media mix of WTR and CW in BRS (called BRS2) with that of a conventional soil mix (called BRS1) in Singapore's context, with due consideration of local climatic conditions and precipitation patterns. Our findings indicate that the environmental impacts of BRS are primarily due to the acquisition (30-90%) and transportation (3-66%) of materials, followed by the operation and maintenance (1-40%) of BRS. Integrating WTR and CW in BRS2 media offers superior environmental benefits (reducing environmental impacts by up to 10%) and proves to be more cost-effective (increasing net monetized profit by about 3%) than the conventional BRS1 media. Our study demonstrates that implementing BRS on a large-scale network can effectively manage water resources, mitigate air pollution and climate change, promote the circular economy, and enhance environmental sustainability. While these results are based on conditions in Singapore, we believe that the general approach toward stormwater management based on nature-based systems is scalable and adaptable to other urban environments with similar climatic conditions.