Ann: Trading Halt, page-84

The State started off in the 1940's with a burried coal deposit that had not been exposed to air for 1000's of years (Upper Series and Main Series overburden shown below) when mining finished a 7km arc of deep coal has been crudely burried and in part virtually left exposed and hence can burn. The ISG operation for that reason is not going to extract gas from the coal say cloaser than 100m from the base of the final pit slope.



Don't know the actuall numbers but in the order of 1000 million tones of carbonaceous shale and mudstone was mined and dump out of then later in the pit to get at the coal used for the Port Augusta Power Stations. Now that could be quiet a compost heap. DYOR.