Quantifying the environmental sustainability of stormwater management systems

Green infrastructure is often assumed to be environmentally beneficial compared to traditional subsurface systems. We tested this assumption by 1) developing a life cycle assessment based method to systematically and holistically quantify the environmental damage and benefit of stormwater management systems, 2) applying it to a case study where we compared two subsurface, and two green infrastructure based systems for the same urban catchment. We showed that both processes associated with the implementation, operation and decommissioning of infrastructure, and discharges of polluted stormwater cause significant environmental damage. The results of the case study highlighted a trade-off between reduced ecosystem damage through advanced treatment, and less damage to resource availability through low-tech, green solutions. The method provided the basis for a simplified tool which allows including environmental sustainability assessment into the planning of stormwater management systems.