Duran, A & Torres, A 2025, 'Piezometer interpretation: coal mine highwalls', in JJ Potter & J Wesseloo (eds), SSIM 2025: Fourth International Slope Stability in Mining Conference, Australian Centre for Geomechanics, Perth, https://doi.org/10.36487/ACG_repo/2535_42 (https://papers.acg.uwa.edu.au/p/2535_42_Duran/) Abstract: The authors present the results and interpretation of the groundwater regimes from multi-tip vibrating wire piezometers (VWP) emplaced in coal mine highwalls. Four case studies are presented, with each case presenting a separate mining area. The data extents for each case vary: one case where there are 10 piezometers in the highwall over a strike length of 2.0 km to another case where 7 piezometers are available over a strike length of 2.8 km. The interpretations have considered: The depth to phreatic surface and variation in Hu (a Hu of 1.0 representing fully hydrostatic conditions and a Hu of 0.0 indicates unsaturated [dry] conditions) down the highwall (i.e. from crest to toe). Where faults crosscut the highwall, and between VWPs, the potential impact of compartmentalisation. The impact near end walls, corners in the highwall, potential aquitards in the highwall and depressurisation from progressive mining. This paper draws conclusions as to what groundwater regimes could be expected in coal mine highwalls. Keywords: coal mine highwall, vibrating wire piezometers, groundwater interpretation