Evaluating Uncertainty in Environmental Impacts from Life Cycle Assessment of Contaminated Site Remediation Options

Environmental remediation of contaminated sites, which involves several energy and resource intensive activities resulting in undesirable emissions and waste streams is one of the significant contributors to the global climate change. Thus, a small intervention in the remedial designs which are environmentally sustainable could substantially contribute towards global efforts for sustainable development. Many researchers have and still use life cycle assessment (LCA) as a common tool to evaluate and quantify the environmental impacts of design alternatives. Although the impact assessment is performed to site-specific and problem specific conditions there is no accord if the results from these analyses are representative and reliable due to significant uncertainty within the input parameters used for the analyses. In this regard, an uncertainty analysis is imperative for any LCA to apprise of the variability in the input data and consequently its influence on the environmental impacts evaluated. In this study, a case study involving the remediation of contaminated sediments is discussed. A baseline LCA of different remedial design options was conducted using the site-specific data. Further, an uncertainty analysis was performed using Monte-Carlo simulations approach to estimate the range of expected values of the environmental impacts for the specified variability of the uncertainty in transportation distances involved in the remedial option implementation. The results show that, for the given site-specific conditions, monitored natural attenuation resulted in the least negative environmental impacts with or without considering the variability in transportation distances in the LCA. However, there was significant variability in environmental impacts of a remedial option based on the uncertainty in the input parameters. Hence, incorporating the sensitivity and uncertainty analysis in LCA is imperative for to more reliably inform the practitioners and design professionals of the range of values for the environmental impacts to be expected.