In late 2021, the potential to extend a very large open pit was investigated. The mine has a high-resolution structural and hydrogeological model, permitting construction of a large-strain, discontinuum, closely coupled hydromechanical finite element model with a much better than inter-ramp scale representative elementary volume. In models of this type, the hydrogeological parameters and constitutive model are also non-linear, so that conductivity and the Biot coefficient are expressed as functions of the modelled plastic strain tensor.