Life cycle assessment (LCA) as a decision-suppport tool for the evaluation of environmental impacts of site remediation on the global, regional and local scale

Life cycle assessment (LCA) was used to compare the environment al impacts of three alternatives for remediating a TCE-contaminated site: (i) enhanced reductive dechlorination (ERD); (ii) in situ thermal desorption (ISTD) and (iii) excavation with off-site soil treatment. In addition, the remediation alternatives were compared to a no action scenario, where only monitoring and natural attenuation takes place. A numerical reactive fracture model was used to predict the timeframes for the ERD and the no action scenarios. Moreover, the model was used to estimate the mass discharge of TCE and degradation products leaching to the drinking water aquifer during these timeframes. These local toxic impacts, referred to as primary impacts, were included in the LCA together with impact on the local, regional and global scale caused by the remediation itself – the termed secondary impacts. The results of the LCA showed that of the three remediation methods compared, the ERD had the lowest total environmental impacts, even though it had significant primary impacts due to its long timeframe. The environmental impacts of ERD were comparable or only slightly higher than those of the no action scenario. ISTD had the highest global warming potential of the three remediation technologies, but excavation proved worse than ISTD in most of the remaining impact categories, e.g. eutrophication, ozone formation, ecotoxicity and human toxicity.