Grande Cache Coal Corporation (GCC) commenced production from the No. 7 Underground Mine in November 2004. The underground mine utilizes the room and pillar method to extract No. 4 Seam coal from gently inclined limbs (flat to 16 degrees) of major folds. This type of structure is prevalent over the property.
This mining method develops roadways into the coal to be extracted, leaving pillars of coal between roads. This is known as the "Development" phase. When the roadways reach the boundary, the pillar of coal between roads is systematically extracted as operations retreat out. This is known as the "Depillaring" phase.
The roadways are driven 2.1 metres high and 6 metres wide. These are developed in 12 metre cuts with the remotely controlled continuous miner moving from one roadway to another, while a roof and side bolting machine moves in to support the roof and side walls. Roof support consists of wire mesh installed with 1.8 metre mechanical bolts in a 1.4 metre square pattern. Plastic mesh is bolted to rib sides for side support.
Continuous mining machines cut and load the coal into shuttle cars and transport the coal from the face to a feeder breaker, which controls the rate and size of the material being fed onto the main belt conveyors. The conveyors carry the coal from the mine to the surface stockpile. The coal is loaded into trucks and hauled to the processing plant.