Incorporating life cycle assessment with health risk assessment to select the ‘greenest’ cleanup level for Pb contaminated soil

Abstract

Green and sustainable remediation (GSR) has emerged as one of the most important pioneering directions in the environmental remediation field. The GSR concept calls for maximizing the ‘net environmental benefit (NEB)’ by taking into account not only the environmental benefit, but also the life cycle environmental cost of remediation operations. However, existing literature to date has not examined how cleanup levels may affect the NEB. In this paper, we proposed a framework that combines life cycle assessment with health risk assessment to derive cleanup levels for remediating contaminated land. This method goes beyond the traditional approach, which focuses on acceptable risk levels to site users. It takes into account the number of potential receptors, as well as life cycle secondary environmental impacts, in order to select the ‘greenest’ cleanup level which maximizes the NEB. A case study was conducted using this framework for a school site with Pb contamination. In comparison with the regulatory guidance value of 255 mg/kg applicable at the time of project implementation, the newly selected optimum cleanup level of 800 mg/kg could increase the NEB by 3%, while reducing economic costs by 36%. The study indicated that as the cleanup level became more stringent, the detrimental secondary impacts of remedial operations increased exponentially, whilst the beneficial primary impact tailed off with diminishing returns. It also showed that more stringent criteria would lead to the cleanup of more widespread areas contaminated by diffusive sources rather than point sources. Overall, the study confirmed our hypothesis that an optimum cleanup level exists when considering both environmental benefit and environmental cost, and the ‘greenest’ cleanup level could be quantitatively determined by calculating NEBs with the proposed framework.