Bartlett, PJ 2010, 'Considerations in planning and implementing massive underground mines at depth', in Y Potvin (ed.), Caving 2010: Proceedings of the Second International Symposium on Block and Sublevel Caving, Australian Centre for Geomechanics, Perth, pp. 359-370, https://doi.org/10.36487/ACG_rep/1002_25_Bartlett (https://papers.acg.uwa.edu.au/p/1002_25_Bartlett/) Abstract: Planning and implementing massive underground mines such as block caves at increasing depths is a process that can extend over many years and carries a considerable level of risk. This paper examines the time that it has taken some major underground mines to plan and implement new mines at depth and the implications of this extended process. Geotechnical concerns are a major source of uncertainty as mines move to greater depths. Gathering, interpreting and using the geotechnical data to plan and implement deep mines adds considerably to the time and uncertainty of the planning process.