Lady Rosie waste rock landform design

Authors: Taylor, I; Critchell, K; Hill, S; Wheeler, P

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DOI https://doi.org/10.36487/ACG_repo/2215_02

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Taylor, I, Critchell, K, Hill, S & Wheeler, P 2022, 'Lady Rosie waste rock landform design', in AB Fourie, M Tibbett & G Boggs (eds), Mine Closure 2022: Proceedings of the 15th International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 81-92, https://doi.org/10.36487/ACG_repo/2215_02

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Abstract:
The Lady Rosie waste rock landform, located at the Westgold Resources Ltd. Cuddingwarra Project in the Yilgarn, Western Australia, was designed to dispose of approximately 1.1 Mt of waste rock. The mine waste material is erodible, with limited competent rock available to encapsulate it. In response, a waste rock landform (WRL) was designed with geomorphic features to reduce erosion, negate the need for rock capping and balance multiple operational and environmental objectives. The design was iteratively evaluated and refined using the SIBERIA landscape evolution model to develop a form capable of meeting the stability-related performance objectives. The model was parameterised from flume testing conducted on the mine materials, to best represent the surface stability when placed. The final design also integrated two sediment basins, as a secondary containment measure to arrest transported sediments and improve environmental performance. The retrofit design received regulatory approval in Q2, 2020, incorporating geomorphic features and removing the previous requirement for rock capping associated with the previously approved conventional form. Westgold completed construction in Q1, 2021. Less waste rock was generated from the Lady Rosie pit than predicted but the flexible design still met the intended objectives. Subsequently, landform evolution modelling was updated based on the as-constructed geometry, confirming that forecast erosion performance remained acceptable. By integrating geomorphic features into the design of the Lady Rosie WRL, Westgold was able to attain regulatory approval, reduce construction costs and achieve environmental objectives using available mining equipment. Early monitoring of the landform WRL indicates the design is performing in accord with the model’s predictions for stability.

Keywords: waste rock landform design, geomorphic, SIBERIA, landform evolution model

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