Ranger leach tank investigation closed

The government of Australia's Northern Territory has decided not to prosecute Energy Resources of Australia (ERA) over the December 2013 failure of a leach tank at the Ranger uranium mine and has closed its investigation into the incident.

A statement issued by the Northern Territory Department of Mines and Energy (DME) today said that based on legal advice, it had decided "that it is not in the public interest to prosecute ERA under the Mining Management Act."

The department issued its decision following extensive investigations into the leach tank failure, which resulted in a spill of about 1400 cubic metres of acidic slurry. Operations at Ranger were suspended for six months while investigations into the incident took place.

Investigations by ERA subsequently found that damage to a rubber liner had allowed the acidic mixture to corrode the steel wall of the tank, leading to its failure. The plant's containment systems - including barriers and channelling - kept all the slurry mixture within the mine's processing area. The failed tank and its supporting infrastructure were dismantled and the clean-up of slurry material in the area around the tank was completed in March 2014.

As well as ERA's own investigation, the site was inspected by staff from the DME, the Australian Government's Supervising Scientist and the Northern Territory's NT Worksafe division. The study by the Supervising Scientist concluded that the incident had not had any detectable impact on the surrounding environment, including the Kakadu National Park.

The DME had been considering whether to bring charges against ERA under section 33 of the Northern Territories' Mining Management Act. In September 2015, the DME received legal advice from Australia's Solicitor General concluding that the release of the slurry, "while avoidable, did not involve positive and voluntary conduct by ERA."

The department acknowledged in its Reasons for Decision that ERA had co-operated fully with it and other agencies "at all stages after the incident." The company had implemented a range of additional governance and maintenance measures as recommended under a process safety improvement action plan set out under an independent report commissioned by the Australia and Northern Territory governments. Quarterly audits over the past year had demonstrated that ERA is implementing the plan and achieving its stated objectives, the DME said.

The DME also noted that its direction to ERA to suspend processing operations for six months saw the company incur a "very significant financial penalty." ERA's net loss due to the suspension was "significantly greater" than the maximum fine of AUD 144,000 ($101,820) that could be imposed for an offence under section 33 of the mining act, it said. ERA's need to purchase uranium oxide to fulfil sales commitments after the suspension of operations at Ranger affected its earnings for 2014 when it recorded net losses of AUD 188 million, compared to losses of AUD 136 million the previous year.

ERA welcomed the DME's confirmation that it would not be bringing charges. "ERA has shown commitment in implementing the Process Safety Improvement Action Plan which has been subject to quarterly audits by government appointed consultants and has continued to engage in an open and transparent process with our key stakeholders. Those audits have found that ERA is achieving its stated objectives in relation to the implementation of the Process Safety Action Plan," it said.

The DME has now formally closed its investigation into the incident.

Researched and written
by World Nuclear News