On Tuesday morning (August 25), in an address to Eurobodalla Council, Matt Darwon president of the Majors Creek Catchment Guardians (MCCG) raised concerns about the validity of technical data contained within the publicly advertised Environmental Assessment for Mod 3 at the Dargues Gold Mine Project (10_0054).
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Mr Darwon referred to information (tabled at the Eurobodalla meeting yesterday) in a report by Dr Emmett O’Loughlin, an engineering hydrologist, formerly Chief Research Scientist at CSIRO Division of Water.
Dr O’Loughlin also addressed Eurobodalla Council and presented the findings in his report to the meeting saying: “The mining company has claimed there is a negligible risk of this dam discharging any waters containing cyanide or heavy metals, even during the heaviest storms or the wettest years on record.”
Dr O’Loughlin said “This claim cannot be supported. The design of the tailings dam is seriously flawed because it used grossly incorrect numbers for the weather at Majors Creek. In fact, the dam is highly likely to overflow, and contaminate the source of Eurobodalla's water with toxic materials.”
Dr O’Loughlin went on to say, “The design of a dam, like this one, must always be based on site-specific weather information: that is, rainfall and evaporation. We rely on the Bureau of Meteorology to provide that data. We use their weather records to calculate if a dam will fill, how much water it will provide, will it overflow, and so on. If the input information is wrong, the answers will be wrong.”
“The Company claimed that it ‘used’ Bureau of Meteorology data from the Braidwood weather station. They did no such thing. Their rainfall figures are incorrect, and their evaporation figures overstate the official figures by 60 percent. Moreover, they ignored the fact that rainfall at Majors Creek is 30 percent more than at Braidwood. These are not trivial errors. They have a major impact on whether or not the tailings dam will overflow, and how often. The nature of the errors is such that the frequency of overflows has been dangerously underestimated.”
Dr O’loughlin mentioned that it took the “critical eye of the official weather observer from Braidwood, Mr Roger Hosking, to see that the numbers used by the mining company for rainfall and evaporation were “not real.”
Dr O’Loughlin had been called in by the Coastwatchers Association and the MCCG to look over a complex study done by Roger Hosking on rainfall versus evaporation at Majors Creek prior to the Modification EA being released.
Mr Hosking and Mr Darwon had been discussing the already approved tailing storage facility (TSF) at the Dargues site prior to the release of the proposed Modification EA. Mr Hosking says that “Curiosity got the better of me. Matt mentioned he had heard stories from the older people at the Creek who spoke of wells overflowing because of the extreme rainfalls in the area. I set about establishing a time line and accurate model based on 68 years of data in order to establish a likely freeboard needed to contain water in a dam located in the area.”
Mr Hosking’s study triggered Dr O’Loughlin’s investigation when the EA went on public exhibition almost 6 weeks ago. “I have no doubt that a competent analysis using correct weather data would show that the tailings dam would spill contaminated liquids and sediments into Eurobodalla's water supplies.” Dr O’Loughlin says.
Mr Darwon says that he’s worried "something doesn’t add up….If the figures used underestimate rainfall and overestimate evaporation at the Creek then surely the TSF design is flawed and the validity of the EA is now in question. I have not spoken to the engineers for the applicant of course, (Knight Piesold) but it will be really interesting to see what they have to say on the matter and to hear where they got their data from."
Submissions to the Department of Planning on the Dargues Gold Mine Modifications close Wednesday 26th August.
Related Story : http://www.braidwoodtimes.com.au/story/3304939/councils-vote-to-oppose-cyanide-processing/?cs=741