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Office of the Supervising Scientist

Estimates & Committees
Scott Ludlam 15 Feb 2012

Additional Estimates - Economics Committee - Tuesday 14 February 2011 - Office of the Supervising Scientist

CHAIR: Thank you, Mr Bailey. I now call the office of the supervising scientist. Welcome, Mr McAllister. Would you like to make an opening statement?

Mr McAllister : No, there is nothing from me.

Senator LUDLAM: Thanks for coming down. We do not have you for very long. Please pass on the committee's best wishes to Mr Hughes, who, I understand, is unable to be here for health reasons.

Last wet season saw some pretty severe impacts on operations at the Ranger mine. Can you give us a rundown of what kind of season they are having up there this year? Have they experienced similar problems?

Mr McAllister : To date rainfall at the site has been in the order of 1,100 millimetres, which is approximately 300 millimetres above average. Most of that fell in December, which was almost a record December; since then, January has been a little bit under average. So they are tracking approximately 300 millimetres above the average.

Senator LUDLAM: About 300 millimetres above for this time of year or for an average wet?

Mr McAllister : For this time of year.

Senator LUDLAM: For how much longer does it keep raining up there?

Mr McAllister : That is highly dependent on the monsoon season. Generally we see an end to the monsoon season sometime towards the end of March or in early April.

Senator LUDLAM: Last year again the company had serious troubles with freeboard on the tailing storage facility, and they were not too far from being concerned about either overtopping or needing to dump water into one of the pits. How much freeboard do they have this year?

Mr McAllister : As you are probably aware, ERA undertook a lift of the tailing stand over the dry season. That put four metres onto the existing height, so it is now certified to a height of 58 metres RL. Currently the level in the tailings dam is at 54.21, so they still have close to four metres of freeboard.

Senator LUDLAM: How much water have they currently got in pit 3?

Mr McAllister : In pit 3, approximately 1,100 megalitres.

Senator LUDLAM: Do you have a sense of the company's time line and strategy for dewatering the pit and getting that out of there?

Mr McAllister : That is highly dependent on the wet season, of course, but I know they are very keen to get to the base of the pit as soon as possible. That will again be highly dependent on how much rain falls and how much they can treat through the pond water treatment system.

Senator LUDLAM: Have there been impacts on mining operations?

Mr McAllister : They certainly cannot access the base of the pit at the moment. They are working on benches above that, so in that sense there have been impacts, but that is something that occurs every wet season.

Senator LUDLAM: But do you have a sense of how long the company intends to take to get the water out of pit 3?

Mr McAllister : Again it depends on how much rain we get. They would want to be in there as early as they could.

Senator LUDLAM: Can you give us an update on the status and time line for the brine concentrator?

Mr McAllister : My understanding is that the ERA's board has approved construction of the brine concentrator and it is still on target to be complete by 2013.

Senator LUDLAM: Do you know when in 2013?

Mr McAllister : The third quarter, I believe.

Senator LUDLAM: Thank you. I think since we last had Mr Hughes here, the proposal for a heat bleach plant has been withdrawn. So now the future of the mine really depends on going underground. My understanding is that ERA is expected to select a tenderer for construction of the box cut and decline in mid February of this year-which you could say we are in now. Can you update us on your understanding of where the company is up to?

Mr McAllister : That is probably as far as we know. I am aware that the company is intending to start construction sometime towards the end of the wet season, into the dry. I do not believe they have done much in the way of preparatory works to date.

Senator LUDLAM: Can you give us a sense of OSS's role re advice and oversight as they move into the construction phase?

Mr McAllister : Our advice will be, as it always is, through the mines consultative committee and to ERA. In relation to the box cut design, we are aware of its design and have commented on that previously. As the construction goes on we will have staff on site, as we always do, through our monthly inspections. That will be a major part of the monthly inspection, I suspect.

Senator LUDLAM: Okay. ERA is understood to have committed to ending mining operations in pit 3 by the end of 2012. Is it your understanding that that is still their proposed time line?

Mr McAllister : Again it is heavily dependent on their access to the pit this year, but I believe they want to get to the bottom of that pit so that they can prepare it for tailings the following year.

Senator LUDLAM: Okay. ERA has completed a life cycle assessment of its uranium product to help inform the company's environmental product declaration. Were you involved, or was your office involved in that process through that assessment?

Mr McAllister : No, we were not.

Senator LUDLAM: I have spoken at length to Mr Hughes about real time monitoring and real time publication of water quality monitoring upstream and downstream of the mine, and it has been a bit of a work in progress. Can you give us an update of when I might be able to go to a website and see, in real time or as close to real time as the instruments allow, the degree of contamination or discharges coming downstream from the mine?

Mr McAllister : In terms of SSD's real-time data, we have a process in place that requires cleaning of that data, which has the data up approximately a week after sampling. One of the issues with continuous data is that the instruments themselves do have anomalous results over time, and you need to check and QA/QC those results and that takes time. In terms of real live data to the web, that is something that we are looking into, but with QA/QC results required to ensure the data is correct. That is something that I could always see will provide a bit of a delay.

Senator LUDLAM: So at the moment it is a week's delay?

Mr McAllister : Yes.

Senator LUDLAM: For the continuous sampling, not for grab sampling?

Mr McAllister : Yes.

Senator LUDLAM: Lastly, we have had extensive discussions about seepage from under the tailings dam. At various times, the company has made undertakings to do water quality sampling as much as is possible from the water that is falling out from beneath the dam. Can you provide us with an update of how much we know, whether there are more accurate estimations of the amount of water that is falling out and whether we have an accurate sense of what is in the water?

Mr McAllister : Following the Weaver report, which was a report that was instigated by ERA and the Gundjeihmi Aboriginal Corporation, the recommendations included the installation of approximately 78 new bores around the tailings dam. To my knowledge, all of those bores have now been installed and we are starting to see the results coming through from those, as at Q4 last year.

Senator LUDLAM: That will tell us a bit about lateral seepage. What about the water that is going straight down? The company and Mr Hughes told us that there is lateral seepage, but that is not where most of it is going; most of it is just heading straight down.

Mr McAllister : To my knowledge, there are no bores planned at this stage for directly underneath the tailings dam.

Senator LUDLAM: So how much do we know about how much water there is and what is in it that is falling out below?

Mr McAllister : From previous studies, I think it was indicated that there is seepage present under the tailings dam and that it is essentially sitting there. The lateral seepage is most important in this instance because that is the seepage that has the potential to express away from the dam, but the seepage underneath is essentially just sitting there, to our knowledge.

Senator LUDLAM: But it is building up year on year. Do we know where it is going? When you say it is just sitting there, water does not just sit there.

Mr McAllister : The hydrology studies that have been undertaken by ERA and in the case of the Weaver report, indicate that the geology under the dam would, I guess, limit the seepage to essentially sit there. It is lateral seepage that is the concern.

CHAIR: Senator Ludlam, we will have to move on, I am afraid.

Senator FISHER: Mr McAllister, I have been listening to your answers to Senator Ludlam. Based on your data from the groundwater thus far, are you able to say whether the measured levels of uranium have any impact at all on the groundwater and, consequently, on the national park?

Mr McAllister : We have really only had one run of sampling out of the new bores. The early data that I have seen indicates that the extent of the seepage laterally away from the dam is as we expected. It is only within 100 metres or so. That indicates that there has been no impact to Kakadu National Park itself.

Senator FISHER: Since your office last appeared before Senate estimates rather than before this committee is self, has there been any material breach of the pretty extensive regulations to which ERA is subject?

Mr McAllister : None.

Senator FISHER: Thank you. In terms of the range of water management initiatives that you have been undertaking, even if there were extensive rainfall in the remainder of the wet season the rainfall would be adequately contained, wouldn't it?

Mr McAllister : Certainly the freeboard within the tailings dam is significant enough to contain at least the worst wet season on record, below the maximum operating level. In addition to that, we have two metres above that for freeboard, so there is plenty of space.

Senator FISHER: You regularly review your management plan so the public can be reassured that you will be looking at it again in advance of the next wet season?

Mr McAllister : We regularly review ERA's management plans. Yes, that is part of the regulatory process.

Senator FISHER: Thank you.

CHAIR: Thank you, Mr McAllister. We now move to program 5.2. I ask the officers to come to the table.

 

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