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Mega-everything: the world’s biggest open cut mine

By Sandra Kanck - posted Monday, 24 August 2009


The expansion of the Olympic Dam mine at Roxby Downs will see environment as the biggest loser. The draft Environmental Impact Statement (EIS), for which public comment closed early in August 2009, has serious deficiencies.

It has been stated, and indeed boasted, by both the proponents and the South Australian Government, that this expansion will result in the construction of an open-cut pit that will become the largest in the world. For those who know Adelaide, this is larger than the whole of the City of Adelaide, including North Adelaide.

There are no plans for filling it at the end of its life: the EIS states “The void created by the new open pit mine would remain as a permanent land feature”. The use of the word “feature” leaves one marvelling at the wonders of spin-doctoring.

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Up to 350 metres of overburden weighing 44 billion tonnes will be removed from the pit to expose the ore. Thereafter up to 390 megatonnes of rock will be removed each year for the next 40 years. Most of this material would be dumped in what will be known as a rock storage facility (RSF). The EIS says it will be visible from a 30km distance, and “would be the most prominent feature in the local and regional landscape”. The proponents propose to shape it so that it will look like a natural feature of the landscape.

The RSF will cover 6,720 hectares to a height of 150m, but BHP Billiton advises that this figure is for the purposes of the EIS only. So it is not surprising to see their proposition of disposing of the extraordinary amount of 8,090 tonnes of vehicle tyres each year into the RSF! That alone must ensure a size increase. But more on the RSF later.

As would be expected from the creation of the world’s largest open cut mine, ore-processing will see the construction of the world’s largest tailings dam - one that will be deliberately designed to leak three megalitres of radioactive waste each year!

The environmental impacts of the expansion will be enormous - from climate change impacts to destruction of biodiversity. In particular, it appears that BHP Billiton has underestimated the amount of native vegetation it will destroy.

Native vegetation destruction and habitat loss

The habitat loss and resultant displacement of fauna would in all likelihood make this the single most environmentally destructive action ever deliberately considered by a South Australian government.

The EIS claims that the total area of vegetation clearance would be between 169 and 173 sq km. This is an aggregated area of more than 13km by 13km and includes the land for the new operations, residential areas and airport, land for the desalination plant, and clearance for pipe and transmission lines.

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Yet based on the scale of the drawings in the EIS, the area of the new pit, the RSF, the tailings storage facility (TSF) and industrial area alone (without any roads connecting any of them) will cover 153 sq km. It is inconceivable then that no more than another 16-20 sq km of vegetation will be destroyed throughout the rest of the project.

Roads will be constructed in the new mining area between the various installations, storage areas will be set aside for vehicles, diesel fuel will be stockpiled etc. Along with the new mining area all of this construction will together account for 264 square km. This is much more than the area claimed for the total of the new developments in this project.

The EIS advises there will be stockpiles of assorted sands, limestone etc which clearly will enlarge the area of native vegetation destruction. Additionally, if the RSF increases in size - and remember the EIS leaves that option open - then still more vegetation would be destroyed. The figures provided by the proponent do not add up!

BHP Billiton has a Significant Environmental Benefit proposal (SEB) - a combination of a financial payout and like-for-like land to be set aside elsewhere -to cover the destruction of biodiversity.

Tens and maybe hundreds of thousands of trees and bushes will be destroyed. The SEB does not have regard to the age of the vegetation. A tree that is decades or even centuries old will not be easily replaced, regardless of whether it is a common species or not. Neither does the SEB appear to incorporate recognition of the fauna that is dependent on those trees and bushes. Whether or not they are common species, they are part of an ecosystem.

Energy use and associated climate change impact

The use of fossil fuels and associated climate change impact will be immense. While BHP Billiton claims the expansion will account for a not inconsiderable 9.8 per cent of South Australia’s CO2 emissions within just 11 years, the real figures may be closer to 14 per cent.

On-site diesel fuel usage will increase from the current 25 megalitres per annum to reach 454,000 kilolitres after 40 years (the mixed measurements are BHPB’s choice). Over the same time period, diesel for transporting material into and out of the site will increase from 16,000 to 36,500 kilolitres.

The EIS suggests potential conversion of haul trucks to run on LNG, resulting in the on-site construction of an LNG conversion facility. With peak oil impacts occurring early on in the expansion, the LNG conversion facility will no doubt need to be fast-tracked. LNG conversion of itself is a process which increase greenhouse gas emissions, yet it does not appear to be included in the climate change calculations.

BHP Billiton will source its electricity needs in the first instance from the current national electricity grid, which will result in the increased use of coal-fired electricity. The closest generators at Port Augusta produce power from relatively inefficient and polluting Leigh Creek coal, with associated greenhouse gas emissions (including the release of methane). At least one of the power-stations is half a century old and should have been decommissioned years ago.

Prodigious amounts of energy will be used in construction. For instance, to allow for the very large equipment that will be moved in, passing bays 30m wide and 250m long will be built between Port Augusta and Olympic Dam at roughly 17km intervals. This and other off-site construction will increase the use of fossil fuels and further blow out South Australia’s climate change targets, yet does not appear to be taken into account in the EIS.

Rock storage facility

The EIS envisages that, 40 years after digging has begun, the pit will be 1km deep. However, ore has been found at a depth of 2.5km, which begs the question of what happens after 40 years. If mining continues, obviously there will be still more rock to add to the RSF, yet this has not been taken into account in figures about its size.

When below-surface rock is removed its volume expands as a consequence of the removal of pressure and being broken-up. This can be given a mathematical value known as the expansion factor. The fine print of the EIS does not reveal any recognition of an expansion factor - it may not have been taken into account at all. Yet BHP Billiton previously informed the Natural Resources Committee of the SA Parliament that the expansion factor would be 1.7 - important information in calculating the size of the RSF.

The pit will be 4.1km x 3.5km x 1km deep, i.e. 14.35 cubic kilometres. If we very generously assume only 90 per cent of what will be taken out of the pit will go into the RSF, it will have a volume of almost 13 cubic kilometres. But with an expansion factor of 1.7 this becomes roughly 22 cubic kilometres.

So the RSF, if 1km high, would have a base of 22 sq km. In turn, if the RSF was to have a base three times that (66 sq km) the height could be reduced to 1/3 of a kilometre, i.e. 333 metres. This is still more than twice the 67 sq km by 150m size envisaged in the EIS.

This strongly suggests the proponents have not included an expansion factor in their calculations. With a 1.7 expansion factor, the RSF would have to be more than twice the ground size stated in the EIS to obtain a height of no more than 150m. But if the intention is to maintain the stated 6270 hectare base, then the height of the rock storage facility will be at least doubled. Which will it be?

Knowledge of the expansion factor will be particularly important in enabling the Native Vegetation Council to accurately determine the amount of vegetation to be cleared and the SEB and/or financial outlay that will be required of BHP Billiton.

Tailings storage facility

Fauna mortalities associated with exposure to the acid liquor of the existing tailings dam were 895 in 2005-06, 311 in 2006-07 and 282 in 2007-08. As well as birds, seven species of mammal and eight species of reptiles have been killed.

BHP Billiton recognises these figures underplay the impact because of the removal of carcasses by scavengers or the sinking of dead birds before detection. They state “If the habitat is modified or increases in area, the number and diversity of species increases accordingly”. So still more birds and animals will be attracted to the world’s largest tailings dam, and still more of them will die as a consequence.

Undertakings are given to put netting in place to deter birds and for further research into methodologies to reduce the number of fauna deaths. The EIS acknowledges that methodologies used to date have had varied success. Despite this, the EIS appears to be leading the public to accept an increase in deaths as being an inevitable cost we will have to bear.

Aboriginal people

BHP Billiton asserts they have reached amicable agreements with the traditional owners of the land. The evidence does not support this.

In 2005 the proponents reached an agreement with Kokatha, Barngala and Kuyani groups to discuss the implications of the project. Questions arise as to why it was only these three groups, and how they established the legitimacy of those who represented the Kokatha people. There is certainly dispute within the Kokatha about this.

And while the EIS acknowledges the Native Title claims of the Arabunna, Dieri, Adnyamathanha, Yandruwandha/Yawarrawarrka and the Nukunu peoples on land through which infrastructure corridors might run, no mention is made of negotiations with them.

The EIS contemplates that the post closure use of land “would be determined by consulting with the relevant stakeholders, including the local government authority, the Roxby Downs and Andamooka communities and the South Australian government”. It speaks volumes that the traditional owners of the land are not specifically mentioned in this list as stakeholders!

But just as happened at Maralinga the traditional owners will probably be left to pick up the pieces.

Conclusion

Although more than four years in the preparation this EIS begs many questions. With government and opposition parties already supporting the expansion, from a legislative perspective this project is virtually unstoppable. But the South Australian and Federal Governments need to thoroughly examine the document, and impose much tougher conditions before they give it the stamp of approval.

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About the Author

Sandra Kanck is the former parliamentary leader of the South Australian Democrats. She is national president of Sustainable Population Australia, SA president of Friends of the ABC, President of the Australian Democrats (SA Division Inc.) and an Executive Member of the SA Council for Civil Liberties.

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