Olympic Dam mine expansion- Environmental impacts of tailings & water by Dr Gavin Mudd – Pt 2

Olympic Dam mine expansion- Environmental impacts of tailings & water by Dr Gavin Mudd – Pt 2


So if you look at it, you can see that the
current site here.. you can see the tailings dams here, but I’ll come back to that. So
we see that that’s our site, That’s over here. Andamooka, Roxby, Adelaide to the South, Lake
Torrens over here and then Arabunna there around Lake Eyre, Lake Eyre South, Lake Eyre
North. So you can see where borefield A is, of course. What’s not marked anywhere on these
maps are all the springs and other important sites that exist on these things. You can
see the large area of borefield B, or wellfield B as they like to say. So in that sense, it’s infrastructure. But
one of the reasons why they’ve gone to the desal plant is, one of the things that, and
I sit on the Great Artesian Basin committee, is they simply can’t get enough water out
of the GAB. With the current expansion and then the expansion after that, the mega-mega
expansion as opposed to just the mega-expansion, they probably need 400 million litres a day,
which will be sucking every single drop out of every single square millimetre of South
Australia’s part of the Great Artesian Basin. Not quite sustainable really, let alone, you
know, economic or anything else like that. Basically picking up on everyone in that part
of the GAB and so on. So um, they’ve gone for the desal plant option,
which is part of how they can build it bigger and so on, and the distance is about the same.
So I think that’s why the logic is.. they’ll keep this. They haven’t committed to shutting
this down as part of the expansion. So these issues will just continue to be there for
a long time. Now this is a photo I use quite a lot. It’s
‘The Bubbler’ mound spring and anyone from BHP along would say ‘that’s outside the influence
of where the impacts are from borefield A.’ Well, no. It’s actually on the margins, and
there is a debate about whether there are impacts at this site or not. But being natural
systems, you can see variability in the way they behave etcetera. But these are very important
cultural sites as well as very important biological and ecological sites as well. So in that sense,
these are the sorts of risks that are being taken in these regions where there’s not much
other regular water coming out of these sort of arid landscapes. So these are critical
features. Certainly I think at the moment, based on
the last 30 odd years, we haven’t seen enough outcomes in making sure these types of sites
are protected, and well protected. Let’s move on to tailings. One of the things
when I was going for my phD is dealing with a tailings dam that leaks like a sieve that
you might use for spaghetti. The design was actually built on top of sand, you know it
had drill holes every five metres in order to work out how much clay there was cause
they dug the clay out of the way to build the tailings dam wall with, exposing all the
sand and wondering why it leaked like a sieve. The question is never about, with any tailings
dam, is never about ‘if’ it leaks. The question is always a matter of rate. One of the problems
of Olympic Dam is they’ve historically always underestimated the rate at which their tailings
dams leak. Then of course back in the day they had an executive who said ‘tailings dams
don’t leak.’ Within a few years they had to admit that they’d lost billions of litres
of water out of the tailings dams at Olympic Dam. So at the moment they’re already 7 square
kilometres, roughly. And that contains roughly, if we think about
the volume of, sorry, the mass of radioactive waste, it’s about 125 million tonnes, that’s
that capital Mt. It’s an important number to keep a hold of, but we’ll come back to
that. At the moment, the current expansion will add probably another 2.6 billion tonnes,
above ground, in an area where due to the depth of the ore body there is no natural
radiation signature at the earth’s surface. So we’re now adding radioactive waste, billions
of tonnes of it potentially, into an area that doesn’t have that sort of fun material
at the surface. Now BHP are proposing as part of the expansion to just cover them up, and
just basically say ‘that’s good enough’ and walk away. ‘We’re here years, we never made
a mistake.’ Now I can say ‘do you want me to start rattling
off all of the accidents, all of
the things? You said nothing would ever go wrong, but they did.’ We’ll see. Let’s come back to that. So really
when you look at it, I think we’ve been sold a dud. All we’ve got… we’ve looked at the
draft EIS, the supplementary EIS… it’s pretty much ‘Business as Usual.’ Nothing much is
going to change. The way BHP have said ‘oh we’ll manage it better’ that’s just because
they’ll slightly reduce the rate of seepage per unit area maybe, but largely business
as usual. Nothing much is really changing at Olympic Dam. Same with the way they’re
processing the ore., except maybe chucking the concentrate to China. So largely, it’s pretty much the same as. So if we look at it, we look at tailings dams,
as I say it’s not a matter of ‘if’ it’s always a matter of ‘how much’. What is the rate of
that leakage? I could say ‘leakage’, I could say ‘seepage’… you know, play word games
and so on if we have to, but what I’m more interested in and what I think is the key
issue is: what are the long term impacts? What are the long term risks? So where does
is go? If it leaks, it’s gotta go somewhere. We have this debate constantly with Ranger
and they say ‘oh, it’s the world’s most regulated mine.’ So fine… you can’t even tell me where
the seepage goes! Then you get to impacts and they’ll say ‘oh,
there are no impacts.’ You’re not even monitoring, how can you say there’s no impacts? So you
look at Olympic Dam, and a lot of that comes back to that same old point. They constantly
underestimate the rate, the pathways and the impacts. So when you look at the expansion, what that
really comes down to is, sure BHP might manage the tailings slight;y better than what we
see here. So the rate might be slightly lower per square kilometre to say they’ve historically
been at Olympic Dam. But when you’ve gone from 7 square kilometres of tailings to 44
square kilometres of tailings, and this is only the first mega-expansion, we’re still
expecting another mega-mega expansion, the total volume and the total impacts are going
to go up, long term. Right and that’s something I’m not convinced
has been addressed properly and the reason that I say that is not because I want to say
it, It’s because I’ve visited sites like Radium Hill. I’ve been through central Western Australia.
I’ve been to places like South Africa where you look at scales of tailings dams or sites
where we have done things like put a cover over the tailings and pretend that we can
walk away from that sort of thing and believe that it’s gonna work forever. Come back ten
years or twenty years later and you’ve got big erosion scales or other problems that
exist. These things don’t work perfectly. So we can’t get something for nothing. That’s
not the way nature works. In that sense, when we look at a lot of these
sort of things,.. right. So you know, one of the big issues which has
come out of the expansion, and again this is one of those sort of myths, is that people
say ‘oh it doesn’t matter if it leaks ’cause there’s limestone underneath.’ And everyone
knows that if you mix acid with limestone, all you get is salt water. Well, sure if you
have perfect mixing and everything else. You know and maybe pigs could fly as well, then
that might work. The problem is, that’s not the way limestone works. You know, now if
I could ask locals of South Australia to name one of their world heritage sites of South
Australia, does anyone know which one it’d be? Mark, you’re welcome to answer. Arkaroola?
No, it’s actually Naracoorte Caves. Naracoorte Caves. When you go to the Nullarbor Plain,
you get huge caves. Huge caves, because they’re limestone. Right? Those caves open up because
you get seepage going through and over time it dissolves lots of limestone, and you get
caves forming. Alright? That’s with rainwater, which is sorta, you know, a very small amount
of acidity. Start adding highly acidic tailing on top of all of that, and you can see why
they lost billions of litres of water in the early days of Olympic Dam. So in that sense, and I don’t say this because
I actually have no evidence or because I want to. Partly it’s obvious. It’s good common
sense science. But we already know this has happened at Olympic Dam. The smaller desalination
plant that already exists at Olympic Dam, to basically produce drinking water for the
township and so on, we can see that in the top left there, it’s got small ponds associated
with it. They were plastic lined and so on. In the early nineties, they lost the whole
thing, because they had this little thing called a ‘cave’ open up. And that was just
with desalinated water, fresh water basically. So start adding on really acidic water at
a scale of billions of tonnes, and then say ‘well, that’s not going to cause these types
of problems..?’

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