The so-called “legacy mine sites” can potentially pose risks to the natural environment. Most of these sites ceased operations before 2005 and pre-dated the Northern Territory government’s policy of requiring operators to lodge a full 100% rehabilitation security bond.
As a result, many mines that operated prior to 2005 have either inadequate or non-existent securities.
Currently the estimated level of historical mining liabilities for the Northern Territory is $1 billion. The NT’s Department of Mines and Energy (DME) said it was in the collective interest of the mining sector to see legacy issues addressed, as their continuing presence was potentially having adverse impacts on the environment and could reinforce community opposition to mining, especially when new developments are being proposed.
The Northern Territory government is seeking to address these liabilities through recent changes to the Mining Management Act (MMA). In 2013 the MMA was revised to deliver a range of improvements to enhance operation of the Act and strengthen environmental regulation. A key component of this was the introduction of an annual levy on mining securities to fund addressing the Territory’s legacy mining liabilities. This is a non-refundable annual levy of 1% on the total calculated rehabilitation cost applied to each mining operation authorised under the MMA. To offset the impact to industry, a discount of 10% in the total security amount payable by operators has been applied.
The DME still holds a minimum 100% security for each site as the 10% discount provided to operators is taken from a calculated security that includes a 15% contingency component.
Under the new arrangements, the levy will be applied to all authorised operators based on the level of security held for each operator’s site as at July 1 each year.
The amount of the levy would not change during the year, even if the security increased in that 12 months, the DME has said.
“Operators are able to pay the annual levy fee in quarterly payments or make other arrangements.
“For operators lodging securities in cash, the 10% reduction in the level of required security provides an immediate net benefit. For those operators lodging securities in the form of bank guarantees, a 10% reduction in the level of required security will result in the paying of a lower annual fee charged by the bank for the guarantee. It will also free up 10% in capital that was originally tied up against the former security.
“It is important to note that the costs used in calculating the security amount are set by the DME and are based on third party costs. That is the costs that would be incurred by the DME should it have to step in and do the work itself. This results in unit rates that are often higher than those that the mining operator would incur if they had done the work themselves.
“The primary objective of the levy is to generate necessary funds to begin addressing historical mining impacts. It is also used to ensure current and future exploration, mining and extractive activities are appropriately regulated to minimise environmental damage. A statutory Mining Remediation Fund has been created with at least 33% of levy funds being held to undertake works to reduce the level of impact legacy sites have on the environment,” the DME said.
A dedicated Legacy Mining Unit (LMU) has been established in the DME, funded by the levy, to undertake these works. Other positions have also been allocated to areas that work on minimising legacy impacts, including water monitoring and analysis.
The LMU is made up of four dedicated team members from diverse backgrounds, including geotechnical engineering, contaminated land assessment, mine closure, spatial science, environmental management and project management. Initial priorities for the LMU include developing an inventory of legacy mine sites for the Northern Territory and undertaking investigations and/or remedial works at priority sites.
While the inventory is being developed, the LMU has started work programs at high-risk sites:
• Monitoring equipment was installed at four sites across the Northern Territory in 2014. The monitoring stations provide the LMU with real-time data on environmental conditions such as pit water level, electroconductivity, creek flow and weather.
• Backfilling and covering of mine shafts from legacy mines commenced in 2015. Mine shafts present a safety risk and have been given a high priority for remediation. The first works were completed at Fossicking Area 4 at Tennant Creek in June, 2015. Further works are planned for sites in surrounding areas.
• Weed control and survey on selected mining tenements around Tennant Creek began in late 2015.
• A tailings dust survey at the Peko Mine Site to determine if there is the any potential for human health impacts from windblown tailings from the site.
• A groundwater investigation at the Redbank mine site to determine the mechanisms for seepage of contaminated water into sensitive waterways.
