ASIMS and MBGS recently completed an analysis on acoustic televiewer data for a major open cut coal mine in the Hunter Valley.  In-pit mapping by mine geologists had recognised the significance of the influence of thrust faults on changing joint set orientations within the mine areas causing instability in the endwall which had to be redesigned, resulting in the sterilisation of 1Mt of reserves.  Based on this observation a project was set up with the key aim to assess the impact of faults in the region on joint set orientation and to follow joint sets through the current open cut area and into the area of proposed mine expansion.  Approximately fifty drill holes were used to define joint sets across the active mining area and into the area of future pit development.  The project successfully identified joint set orientations as they change direction throughout the deposit allowing medium to long term planning to minimise risks associated with endwall stability.