Tuesday 21 August 2012

Hansard of the Legislative Council


[3.46 p.m.]

Mr FINCH (Question) - Madam President, I ask the Leader:

(1) When will the government repay the former Beaconsfield Gold Mine operator, BCD, its environmental bond of more than $2 million?

(2) How will the remediation measures at the mine be assessed for the repayment?

(3) What contingency plans are in place to protect the people of Beaconsfield for any groundwater contamination from cyanide and arsenic, due to the placement of toxic tailings in the mine?

(4) Does the government have faith in the statement by BCD that the Beaconsfield mine is a depleted resource, given some estimates that suggest that the Beaconsfield mine still contains the largest and the highest-grade gold resource in Tasmania?

Mr FARRELL - I thank the member for Rosevears for his questions. The answer to part 1: the security deposits for mining lease ML1767P/M BCD Operations Pty Ltd Beaconsfield will not be returned to the company until all rehabilitation obligations have been met by the lessee. This is expected to take a number of years.

Part 2: An assessment as to whether the rehabilitation obligations have been met will be made against the agreed rehabilitation criteria as set out in the approved Decommissioning and Rehabilitation Plan, the DRP, for the site. This process will be undertaken jointly by the Environment Protection Authority and Mineral Resources Tasmania.

Part 3: Leaving tailings in surface dams does not result in greater environmental benefits for protection than deep underground disposal. The sequestration of tailings deep within the mine has been determined to be the lowest risk option for long-term storage of the material. The Beaconsfield mine has a cyanide destruction unit. The Environmental Protection Agency will require destruction of cyanide to very low levels prior to discharge to the mine and the mine air will be monitored for hydrogen cyanide levels. No tailings will be deposited above the 375 metre level, the depth of the historic mine workings. Arsenic that was present in the ore taken from the mine will be in the form of stable ferric arsenate in the tailings as per accepted best practice for managing arsenic in the gold industry. In the time between sequestration of the tailings and the mine void flooding to the near surface groundwater aquifer, any residual cyanide will have to be detoxified by bacteria lost to atmosphere as hydrogen cyanide and/or complex with iron that is present in the groundwater.

When the mine is flooded there will be more than 355 metres of fresh water overlying the denser seawater pumped in with the tailings, ensuring density separation of the waters. Any residual metal sulphides and base metal hydroxides in the tailings will remain insoluble, given the alkalinity provided by the seawater, carbonate minerals in the tailings and mine water. Subaqueous disposal of sulphides is accepted practice in the mining industry.

Mr Finch - Have you got any technical details?

Mr FARRELL - Not quite, no. I am just so pleased I did grade 10 chemistry.

The government is satisfied that on review of the economics, geology and engineering complexities, the decision for BCD to close is substantiated. Closure planning is a complex scientific and engineering planning exercise with lots of big words, which has been undertaken transparently with the relevant state government bodies.