Johnson, JD, Fergusson, D & Guy, G 2007, 'Risk Based Slope Design for Opencast Coal Mines at Rotowaro, Huntly, New Zealand', in Y Potvin (ed.), Slope Stability 2007: Proceedings of the 2007 International Symposium on Rock Slope Stability in Open Pit Mining and Civil Engineering, Australian Centre for Geomechanics, Perth, pp. 157-170, https://doi.org/10.36487/ACG_repo/708_9
(https://papers.acg.uwa.edu.au/p/708_9_Johnson/)
Abstract: This paper presents an overview of the history of open pit slope design within the Rotowaro Coalfield, 
Huntly New Zealand and discusses how these approaches have been successfully adopted in recent years to 
manage slope instability risk. Discussion is presented on the application of conventional 2-dimensional slope 
analysis at Rotowaro and the background to the development of quantitative risk-based slope design 
methods. The application of a ‘risk volume’ as design criteria is outlined. The limitations of these 
approaches for larger slopes are noted and discussed. Comparisons of 2-D and 3-D analytical approaches 
using limit equilibrium methods are presented. A discussion on the validity of assessed weak rock mass 
strengths at high normal stress is also provided, together with how these effects are being investigated using 
numerical models. A comparison of slope stability findings from limit equilibrium and finite difference 
modelling are discussed along with the implications for slope design and risk management.