Not long after Wollongong Coal was forced to shut down their Wongawilli mine due to safety and financial problems, they held a “community information session” on the proposed extension of the Russell Vale coal mine.

On the 25th of May – the same day a climate change rally was held in Wollongong – Wollongong Coal opened the doors of the Thirroul Community Centre to the public. The location choice was a bit strange, given that it was not held in suburbs that would be directly affected. Any Illawarra local worth their salt can tell you that parking in Thirroul on a sunny Saturday is a challenge. Perhaps just an oversight.

Upon arrival, locals were greeted by the cheerful staff of Umwelt. This is the Environmental Consultant Agency to which Wollongong Coal has no doubt paid a pretty penny, to chaperone each visitor through the presentation.

Each visitor was given a glossy booklet, complete with serene pictures of miners walking through the bush.

We were informed that the booklet was “more detailed” than the posters on the walls.

On further inspection, it seemed that several sections were omitted from the booklet – in particular the noise and dust contour maps.

Sure, they had pictures of them on the walls, if you could distinguish the dark blue contour lines from the dark green background. But unless you have a photographic memory, you couldn’t possibly recall the details of the maps.

Not to worry – we took our own pictures, and have provided them for you here.

Also missing from the booklet included the proposed colliery site plan. Not to mention proposed stockpile sizes for Run-of-mine coal , product coal and waste material.

Perhaps not surprisingly, there were zero attempts to estimate the Green House Gases that would be emitted by the expansion project.

Importantly for us, Wollongong Coal completely glossed over the issue of subsidence. Subsidence is the vertical shifting of earth which can cause cracks to appear in the surface, water loss and contamination. Although subsidence is much more prominent with longwall mining, is still occurs with bord-and-pillar mining. A simplistic diagram drawn up by geotechnical consultancy firm Strata Control Technology (SCT) seeks to show that the “typical” subsidence for first workings bord-and-pillar extraction is virtually none.

According to Department of the Environment [1] :

“Historically, this method of mining [bord-and-pillar first workings] was undertaken where the depths of cover were very shallow, the mine was small, or where the surface subsidence had to be limited” pg. 4

Note the key word; limited.

Bord-and-pillar first workings are not employed to eliminate any risk of subsidence, but rather limit the risk. In areas of the water catchment where an individual can be fined up to $44,000 for simply bushwalking, is it really acceptable that subsidence is merely limited?

Furthermore, the report [1] continues:

“where the pillars have been designed to be stable, the vertical subsidence is typically less than 20mm. Natural or seasonal variations in the surface levels, due to the wetting and drying of soils, are approximately 20mm; hence, vertical subsidence of less than 20mm can be considered to be no more than the variations that occur from natural processes and should have negligible impact on surface infrastructure” pg. 4

Firstly, the argument that mining companies should be able to deliberately cause up to 20mm of subsidence because similar variations may occur from natural processes – is a bit like an arsonist who feels it is quite within his rights to start a bushfire because they can also be caused by lightning strikes.

One would assume that there is a fundamental difference between changes in the “wetting and drying of soils” (which are presumably located in the top layers of the earth) and subsidence caused by the sinking of underlying strata.

This begs the following question, wouldn’t the 20mm of subsidence caused by underground mining simply be added to the natural variation that would occur in the soil, and not necessarily negate it?

Perhaps these are moot points when we consider that the 20mm subsidence figures are “best-case-scenario” estimations.

According to one researcher [2]; ‘Pillar design criteria based on field experience have met with mixed success”

Not only do unexpected things go wrong but we also know from scientific literature [3, 4, 5] that significant levels of subsidence occur over time due to the eventual degradation of support pillars. The mining company is only responsible for the health of the area for a relatively short period of time and wouldn’t be held responsible for any damage that occurs in the distant future.

Given all of this information – do we really trust a company that has been in doubt as to whether it is even fit to hold a mining licence, to perform underground mining beneath our most precious resource?

Sydney is the largest city in the driest inhabited continent on earth. POWA believes our water is our lifeline, and needs to be protected at all costs.

References:

[1] Department of the Environment, June 2014, Background Review: Subsidence from coal mining activities, Commonwealth of Australia

[2] Galvin, J. 2016. Ground Engineering: Principles and Practices for Underground Coal Mining.

[3] Bell, F.G. & de Bruyn, I. A. (1999), Subsidence problems due to abandoned pillar workings in coal seams, Bulletin of Engineering Geology and the Environment, 57, pp. 225-237

[4] Taylor, J., Fowell, R. & Wade, L (2013), Effects of abandoned shallow bord-and-pillar coal workings on surface development, Mining Technology, 109(3), pp. 140-145

[5] van der Merwe, J.N. (2003), Predicting coal pillar life in South Africa, Journal of the South African Institute of Mining and Industry, pp. 293-302