Acceptable erosion rates for mine waste landform rehabilitation modelling in the Pilbara, Western Australia

Abstract

A major concern for rehabilitation and closure of waste landforms on mine sites is their long-term erosion stability. In Western Australia, regulators are requesting landforms remain 'stable' for hundreds of years or the 'long-term'. Therefore, assessing a landform's potential long-term erosion stability requires the use of erosion and/or landform evolution models and defensible erosion thresholds below which rehabilitation landform designs are considered acceptably erosion resistant or 'stable'. The Pilbara Rehabilitation Group, through four member companies-BHP, Fortescue Metals Group, Rio Tinto, and Roy Hill-initiated a project aimed at defining acceptable rates of erosion for rehabilitation landform design for the Pilbara region of Western Australia. As part of the project, a review of information relating to erosion rates on natural and man-made landforms was conducted. This review showed that a wide range of approaches have been used to define acceptable erosion rates, including linking them to rates of soil formation; maintenance of soil quality, which may include considerations of plant/crop productivity, effective soil depth, and soil organic matter and nutrient stores; rates of natural erosion in adjoining areas; potential for gully formation; and water quality impacts. Based on this review, a guideline was developed to define acceptable erosion rates for use in the design of stable mine waste landforms in the Pilbara region. The guideline uses a risk-based approach, with erosion thresholds being linked to the waste material's physical properties and the adverse environmental impacts that may result from landform failure.

Geomorphological Mapping and Erosion of Abandoned Tailings in the Hiendelaencina Mining District (Spain) from Aerial Imagery and LiDAR Data

“…On the other hand, there is a higher density of vegetation, including herbaceous species, in the central depressed area of the south pond, which is subject to temporary flooding and, therefore, better retains the mobilized tailings. Steep hillsides in abandoned mines register maximum erosion rates due to the higher surface runoff along rills and gullies [21,53]. Recent studies suggest geomorphic mining reclamation to mitigate the loss of mine waste [19].…”

Measuring the Land Use Based Risk of Soil Erosion in a Mining-Dominated landscape in Northern Iran

“…The acceptable erosion rates for mine waste landform rehabilitation should be determined. Howard and Loch (2019) suggested an approach to link the erosion thresholds to the waste material's physical properties and measure acceptable erosion rates for this landform. The adverse environmental impacts that may result from landform failure should also be assessed carefully.…”