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Once Pit and Blocks have been defined Passes and Lifts can be established. In 3d-DigPlus structures called Excavation Templates are used to set up and define excavations. Excavation Templates control the extents of an associated excavation. Excavations can be bound to a surface (bench, coal seam etc.) and constrained by design surfaces (pit shells). One Excavation Template is required for every Strip to be modelled in a particular Pit.

The first stage in setting up an excavation sequence is to create a Staged Excavation. Staged Excavations allow users to define the Passes to be excavated and to refine the Passes with Lifts. Once the Staged Excavation setup is complete the system creates a Raw Sequence. A Raw Sequence consists of the full set of incremental steps required to excavate a complete Strip of a Pit. Each Step in the Raw Sequence represents the excavation for a Block of a Lift for a Pass (e.g. Block 0-Upper Seam Pass-Lift 1).

Once a Raw Sequence exists, groups of raw Sequence Steps (typically contiguous groups) can be assembled into Subsequences. Subsequences are then assembled into Supersequences which are the schedule for the Simulation. Supersequences can span Pits and Strips.

Influence of Geology on Modelling Methodology.

There are two aspects of geology which can influence the setting up of Staged Excavations:

1.Seam dip and topology.

2.Continuity of seams.

Deposits with a maximum seam dip of less than 10 degrees are generally referred to as flat to moderate dip. Such deposits typically have pits oriented along strike with subsequent strips advancing down dip. In such cases waste stripping and coal recovery usually involves the removal of waste and exposure of the coal seam over the entire strip, or a substantial section of the strip, followed by coal removal.

Deposits were the maximum seam dip is in excess of 10°, or with otherwise complex topology, are referred to as steep dip. Such deposits usually require pit design and orientation  which focuses on the need to make feasible the exposure and mining of coal in a manner that allows truck and shovel access. Frequently this involves excavating the waste to a particular bench level and removing whatever coal formation is exposed with this bench, before proceeding to the next bench down.

Coal seams may also be subject to significant discontinuity. A particular seam may exist over the extent of a Pit but be viable in only a subsection of the Pit.

In this topic, and the topics immediately following, the setting up of Excavation and Lifts is described in general terms but with specific reference to deposits with low to moderate dip and contiguous geology. Several topics follow which extend this methodology to specific issues of steep dipping deposits and non-contiguous coal seams.