Evaluating Land-Use Impacts: Selection of Surface Area Metrics for Life-Cycle Assessment of Mining

Land use is an increasingly important component of sustainability evaluations, and numerous performance metrics have evolved to meet this need. The selection of appropriate land‐use metrics for decision makers, however, remains an ongoing challenge. Additionally, life‐cycle practitioners often struggle to provide meaningful impact assessment because of challenges associated with traditional land‐use impact metrics. This article is intended to assist decision makers and life‐cycle practitioners who wish to more effectively measure and evaluate one aspect of land use: surface area occupation. Existing performance metrics are discussed, and the specific circumstances under which each is appropriate are identified. Building on leading‐edge research and analysis in the field of life‐cycle impact assessment, a modified methodology for evaluating surface area occupation is proposed. This approach is demonstrated for a series of mining practices including three individual gold mines, a bauxite mine, and a copper mine. The specific data requirements and resulting equivalency factors for each mine are discussed. Results indicate that equivalency factors for gold (average of 700 acre‐yr/ton) are expected to be several orders of magnitude higher than for either bauxite (0.004 acre‐yr/ ton) or copper (0.03 acre‐yr/ton). These dramatic differences in results demonstrate that equivalency factors are appropriate and necessary for including land‐use impact potential as part of a life‐cycle assessment that includes several different minerals or material requirements.