Closure and post closure

To better understand the details of the bonds and the Trust, it is necessary to also understand the meaning of the terms relating to closure and post closure.

1. Operational period
Mining operations continue where possible, disturbed areas are progressively rehabilitated.

2. Closure period
OceanaGold rehabilitates remaining disturbed land while continuing to monitor and maintain the site.

3. Post closure period
The Trust takes title to land upon which the tailings storage facilities and water treatment plant stand and the parklands adjacent to the lake. The Trust monitors and maintains the land in perpetuity and obtains insurance cover where necessary.

Closure commences once mining stops, and closure continues for a number of years. Closure is complete when ‘the elements of the entire project have been demonstrated by the Company, to the satisfaction of the appropriate regulatory authorities, to have reached a safe, stable, self-sustaining, rehabilitated state.’

A safe, stable, self-sustaining rehabilitated state is defined to have been reached when:

  • the pit slopes are shown to be stable
  • any water discharging from the site, and any groundwater under the site, will be of a quality that will not affect aquatic life, or other users of the water resource
  • the structures are shown to be stable
  • all revegetation is complete, and monitoring demonstrates that the site is sustainable.

Because it will take five years for the lake to fill, and another five years of monitoring of the lake water quality will be required, it is assumed that the closure period will be ten years in duration. In practice, much of the site will have been rehabilitated and will meet the closure objectives well within that ten year period.

Once closure of the site is complete, the post closure period commences. At this point in time, a charitable trust known as the Martha Trust will manage the tailings storage facilities and water treatment plant and take title to the land upon which they stand. The Trust will also take title to the proposed parklands adjacent to the lake, and maintain it for general use by the public. The Trust will also be responsible for the monitoring and maintenance of the lake. A sum of money will be handed over by the Company, and the interest generated from that money will allow the Trust to manage, monitor and maintain the land, and provide the necessary insurance cover.

The Trust will be responsible for maintaining the land and facilities in the long term, and will carry out all necessary monitoring and maintenance.