Comparison of the Erosional Performance of Alterative Slope Geometries

McPhail, Gordon; Rye, Catherine

doi:10.36487/acg_repo/802_24

Cited by 3 publications

(3 citation statements)

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“…The lateritic nature of much of the topsoil material does with time result in the formation of a thin outer skin that if not broken provides protection against wind erosion but not against concentrated (channelised) water flow ( Figure 7). The erodability of soil covers appears to be influenced more by slope length than slope angle (McPhail & Rye 2008). Many upper slopes are seen to over time develop what appears to be a convex profile that suggests a form of slope creep has occurred on what might originally have been the steeper upper section of a designed concave slope profile.…”

Section: Environmental Impactsmentioning

confidence: 99%

A common-sense approach to mine closure design in the remote Western Australian interior

Wright¹

2016

Proceedings of the International Conference on Mine Closure

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In recent years Western Australia has seen a far greater focus on mine closure planning, with both the Government and the Mining Industry tackling implementation of rather conceptual mine closure strategies that are set early in the mine life. Both practitioners and Government stakeholders have the best of intentions when setting mine closure objectives, standards and completion criteria, but just how realistic are these when it comes to implementation? This paper looks at what might be considered both pragmatic (cost-effective and achievable) and responsible with regard to mine closure in the arid WA Goldfields region. It draws on twenty years of keen observation of the successes and failures of mining industry efforts in this region and recent scientific findings by several local consultants. The focus is on closure design of those mine landforms that remain post-closure-mine pits, waste rock dumps, stockpiles, leach pads and tailings storage facilities. It examines the actual set of field conditions under which mines operate, post-closure modelling time frames and research (and predicative modelling) limitations. The paper suggests where closure design efforts should be focused and how best we might interpret the current WA Government mine closure guidelines. It identifies several closure design aspects that remain misunderstood by many stakeholders, resulting in unrealistic expectations and closure criteria.

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Section: Environmental Impactsmentioning

confidence: 99%

A common-sense approach to mine closure design in the remote Western Australian interior

Wright¹

2016

Proceedings of the International Conference on Mine Closure

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“…Shoreline erosion modelling is just one aspect of broader pit lake catchment rehabilitation and erosion management, which often must consider alternative slope geometries (McPhail & Rye 2008). By not requiring the specific formative conditions that some models require (e.g.…”

Section: Conclusion and Recommendationsmentioning

confidence: 99%

Process-based erosion modelling for shoreline rehabilitation design of a coal mine pit lake

McCullough¹,

Rooijen²,

Maren³

2019

Proceedings of the International Conference on Mine Closure

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Mine pit lakes are a common feature of open cut mine closures that extend below the local groundwater levels. Due to the relatively steep lake bottom profiles compared to natural lakes, shoreline stability remains a significant limitation for the long-term sustainability of many pit lakes, potentially impacting upon highwall geotechnical stability, revegetation success, water quality and proposed end uses including wildlife habitat, aesthetics and recreation. However, although a potential issue for long-term pit lake closure planning and management, there is currently very little information available on pit lakeshore erosion, including potential erosion rates and extent.The ENGIE Hazelwood Coal Mine project is located in the Latrobe Valley, Victoria. The site has ceased operations and is currently in closure work phase. With approximately 16 km of pit lake perimeter, the effect of the final pit lake shoreline design on wave-induced shoreline erosion was identified as a key area requiring further study.This innovative study used the process-based hydro-morphodynamic models Delft3D to predict final pit lake shoreline erosion at the Eastern Batter (EB) domain region of the pit void. Shoreline erosion modelling was undertaken for three erosion treatments over a total of 10 scenarios. Effect of sediment type (clays, sands and clay/sand mixtures).2. Effect of shore slope angle (design angle of 17° from horizontal, to a lower 12° and steeper 22°). The effect of prevailing winds compared to episodic storm winds.Pit lake shoreline erosion modelling was found to be a useful design tool for to study pit lake shoreline developments. Further model findings were that relatively gentle (12°) slopes did not show substantially decreased erosion rates compared to design (17°) slopes. However, relatively steep (22°) slopes showed substantially greater erosion.Erosion rates were strongly influenced by sediment properties, which constituted the biggest uncertainty in the modelling. Lowest erosion rates were for cohesive grey clays, highest erosion rates for sands and erosion rates of mixed sediments were in-between. Eroded sands were also deposited nearby at slightly deeper water, thereby reducing shoreline slopes over longer timescales. However, eroded clays were dispersed throughout the lake, preventing an erosion/deposition equilibrium being reached. Short-term storm events simply mimicked erosion patterns of longer duration prevailing wind events. Consequently, slope and sediment characteristic choices to mitigate prevailing wind effects may be similar to those used for mitigating event-driven erosion.

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“…It has developed its own guidelines to, at least in part, fill this regulatory void and uses its own auditors to visit these mine sites. It is unfortunate that its latest guideline published in September (IFC, 2007) appears to support the development of landforms that increase the risk of waste landform erosion after closure through advocating the construction of berms, which McPhail and Rye (2008) demonstrate as a potentially high erosion slope option. In this case being IFC compliant will not necessarily be in the best interest of the environment.…”

Section: Financial Organisationsmentioning

confidence: 99%

Environmental compliance

Jones¹

2011

Mining Technology

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The Macquarie dictionary defines 'compliance' as '1. An act of conforming; acquiescing, or yielding. 2. base subservience.'. Does environmental compliance mean yielding to environmental forces, or does it mean being subservient to a human perception of the environment? How 'environmental compliance' may be defined by the various stakeholders in the mining industry, companies, governments and communities is considered in the light of their possible objectives in requiring 'environmental compliance'. Examples of potentially conflicting environmental requirements in waste management are considered, particularly operational requirements such as minimal dust generation versus completion environmental compliance requirements of establishing a selfsustaining ecosystem or geomorphologically stable landform. Mechanisms available to establish standards for determining if environmental compliance has been attained are described. These include guidelines (company and government), which can range from detailed (tailings construction) to broad and general (closure strategies); codes of practice, ministerial conditions and regulations are discussed. Some of the strengths and weaknesses these mechanisms are described, using examples from industry experience. The site specific nature of most mine waste management operations means that one approach cannot fit all situations and the fairness of having a solution acceptable in one operation, but not in another is discussed. Does strict compliance with a human perception of the environment and how it functions promote a 'lowest common denominator' approach? The potential technology restricting aspects of requiring 'compliance' is discussed and the alternative compliance requirements of 'outcome' compliance and 'process' compliance considered. The time frame for assessing environmental compliance is discussed. The potential use of simulation models as potential tools for assessing future environmental performance is considered. Moreover, it is concluded that 'environmental compliance' means conforming to the environment rather than simply acquiescing or yielding to man-made 'rules'.

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Comparison of the Erosional Performance of Alterative Slope Geometries

Cited by 3 publications

References 0 publications

A common-sense approach to mine closure design in the remote Western Australian interior

A common-sense approach to mine closure design in the remote Western Australian interior

Process-based erosion modelling for shoreline rehabilitation design of a coal mine pit lake

Environmental compliance

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