The Ulan Seam generally dips uniformly towards the north-east at between one and two degrees, and the seam thickness averages 5 to 7 metres (see Stratagraphic Profile) throughout the Ulan Mine Complex. It consists of ten separate plies, which are consolidated into four working sections within the open cut. The working sections are separated by thin claystone horizons.
Current planning is for the open cut extension to mine the full seam, and the underground operations will mine the lower section of the Ulan seam. The lower section has low ash content and an average thickness of 2.75 metres; varying from 2.4 metres in the north-west, and up to 3 metres in the south.
Within the areas to be worked throughout the mine life, the depth of cover will generally increase where extraction progresses toward the north east, due to a combination of topography and a dipping seam.