Once implemented, compliance with the Code will go a long way to ensuring the relevant law concerning the development, operation and rehabilitation of tailings storage facilities is complied with.

The development, operation and rehabilitation of tailings storage facilities for mining operations is primarily governed by the Mines Safety and Inspection Act 1994 (WA) (the MSIA) the Mining Act 1978 (WA) and associated regulations. The potential environmental issues presented by tailings storage facilities also attract licensing and approval requirements under other State and Federal laws concerning the environment, water, native title and Aboriginal heritage

There are currently guidelines in place for tailings storage facilities in Western Australia, Guidelines on the Safe Design and Operating Standards for Tailings Storage (1999), that were released by the WA Department of Mines and Petroleum (DMP) in 1999.

A new Code of Practice for Tailings Storage Facilities, currently in its second draft phase after initial feedback received in late 2012, is to be issued by the DMP under MSIA and the Mining Act. It is intended that the new Code will complement the existing Guidelines that the DMP says will be reviewed this year.

The DMP is currently calling for comment on the second draft of the Code, with submissions due by 5pm, Friday 24 May 2013. Following completion of this second round of public consultation, the draft Code will be submitted to the Mining Industry Advisory Committee for endorsement. The Code will then come into force when approved by Minister and gazetted.

Importance of adequate planning and operation of tailings storage facilities

For the purposes of the draft Code, a tailings storage facility is a reservoir that stores mine tailings, that is, waste material discharged from an ore processing plant or coal preparation plant. The Code will not apply to waste dumps, heap or vat leaching facilities, or underground mine fill.

Disposal of mine tailings typically represents the most significant environmental liability associated with mining operations. Without adequate long-term planning, final rehabilitation of a tailings storage facility can be very costly, at a time when there is generally limited or non-existent cash flow for a mining company. Tailoring the design of a tailings storage facilities to site conditions, and minimising environmental impacts, can lead to a reduction in total project costs, and minimise the risk of incidents and prosecutions.

The draft Code sets performance-based standards that promote monitoring and surveillance during construction, operation, and prior to closure so as to better predict a tailings storage facility's long-term performance and potential environmental impact after closure.

The draft Code

The draft Code sets out the different stages in the tailings storage facilities life-cycle of site selection, design, construction, operation, emergency planning, management and rehabilitation.

A primary aim of the draft Code is to provide a set of outcomes for tailings storage facilities to meet the approval requirements for:

  • a project management plan under the MSIA and regulations;
  • a mining proposal under the Mining Act; and
  • a review report under conditions applying to mining tenements imposed under the Mining Act.

The draft Code also describes what must be demonstrated to show that a tailings storage facility is safe, stable and non-polluting, and outlines the broader occupational health and safety requirements for operating in accordance with the MSIA.

The Code applies to and describes the role of a "competent person" in relation to tailings storage facilities, who defined as "someone who is appointed or designated by the employer or tenement holder to perform specified duties which the person is qualified to perform by knowledge, training and experience". The competent person's role in the hazard management process for tailings storage facilities includes selecting an appropriate site for their construction and conducting monitoring and surveillance.

General (rather than prescriptive) guidance is given in the draft Code as to the design of a tailings storage facility, as it must satisfy the safety requirements of the MSIA and regulations, the environmental requirements of the Mining Act and regulations and the Environmental Protection Act 1986 (WA), among other applicable State and Federal laws. Specific requirements also exist for the storage of radioactive waste (eg. from uranium mines), with the facility's design and management needing to meet safety standards imposed in accordance with specific codes of practice and international safeguards.

The guidance set out in the draft Code is targeted to assist companies in being adequately prepared for rehabilitation of a tailings storage facility when the project reaches its conclusion. Tailings storage facilities are a critical closure issue for mines, and the Code recognises this by requiring the production of a tailings storage facilities plan in line with an overall mine closure plan under the Mining Act.

For the purposes of the MSIA, a code of practice is admissible in court as evidence in a proceeding for an alleged related contravention of the MSIA (although compliance with a relevant code of practice is not a complete defence to an alleged contravention).

While in many respects the draft Code is just a signpost to the more prescriptive regulations that apply in developing, operating and rehabilitating a tailings storage facility, when implemented the Code will provide a guide to achieving the standards set by the legislation and, if followed, go a long way to ensuring the relevant law concerning tailings storage facilities is complied with.