Combined Use of Life Cycle Assessment and Groundwater Transport Modeling to Support Contaminated Site Management

ABSTRACT

The subject of this study is a spent pot lining (SPL) landfill. The aim of this study was to identify the site remediation option, among four alternatives, that minimizes overall environmental impacts based on: 1) a comparative life cycle assessment (LCA); and 2) modeling of contaminant transport in groundwater. The four options were: leaving the landfill in place (Option 1); excavation of the landfill, with on-site disposal of the excavated materials in a secure cell (Option 2); excavation of the landfill, with treatment of the SPL fraction (Option 3); and excavation of the landfill, with incineration of the SPL fraction in a cement kiln (Option 4). The LCA was performed following the guidelines provided by the International Standard Organization (ISO). Furthermore, to improve the relevance of LCA to site remediation sector, impacts caused by residual in-situ contamination were assessed by applying a simulation of contaminant transport in groundwater, using site-specific data. The LCA identified Option 1 as having the least environmental impacts. However, the transport modeling concluded that contaminant concentrations 50 years from the present could be approximately 30 to 40 times the regulatory criteria if this option is retained. In addition, this study demonstrated that LCA can be used as a screening tool to help identify significant environmental issues; the LCA identified acute and chronic water ecotoxicity categories as being the dominant impact categories of the environmental profile and consequently, it is recommended that a complete environmental risk assessment (ERA) be performed for Option 1.

Keywords:

• site remediation
• LCA
• modeling of contaminant transport in groundwater
• site-specific assessment.

ACKNOWLEDGMENTS

The authors acknowledge Michel Mailloux, Laurent Saumure, Doug MacDonald, and Dan Walker for their contributions and valuable advice in the preparation and review of this article, and the partners of the NSERC Industrial Chair in Site Remediation and Management for the financial support: Alcan, Bell Canada, Cambior, Canadian Pacific Railway, Centre Expertise Analyse Environnementale du Québec (CEAEQ), City of Montreal, Gaz de France/Électricité de France, Hydro-Québec, Ministère de la Métropole (Gouvernement du Québec), Natural Science and Engineering Research Council (NSERC), Petro Canada, Total and Solvay.

Notes

*Calibrated values