From the Proceedings of the Sixth Australian Workshop on Acid and Metalliferous Drainage, held in mid-April 2008 is a valuable paper by M. Phillips, D. Hockley, and B. Dawson. Their paper is entitled: Sullivan Mine Fatalities Incident: Preliminary Technical Investigations and Findings.

We all recall the Sullivan Mine accident of May 2006 in which four people died in a small shed at the toe of the waste rock dump. They all died of a lack of oxygen in the shed that was built to protect a water sampling pit.

There have been enquiries, judicial sessions, and recriminations since. This paper is a welcome change: it reports on the technical factors that caused the conditions that killed the four. And the paper sets out guidelines for other mines---in the hope that these guidelines will preclude a repeat of this accident elsewhere.

I take the liberty of quoting below the guidelines that conclude this paper. Also in the hope that in so doing we may contribute to a safer mining environment everywhere.

“While data continues to be gathered and assessed, the Technical Panel [on the Sullivan Mine accident] believes that all individuals responsible for safety on mine sites should be aware of the hazards associated with waste dump air, and that the risks should be stated as broadly as possible. Based on the findings to date, the presence of any of the following should be considered to significantly raise the risk:

  • Sulfide minerals in waste rock, which can deplete oxygen from the air.
  • Any combination of sulfide minerals and carbonate minerals, which can lead to production of carbon dioxide.
  • Air temperatures that are higher than temperatures within waste dumps, which can lead to temperature driven outflows of dump air.
  • Sharp drops in barometric pressure, which can lead to pressure driven outflows of dump air.
  • And factors that serve to concentrate or confine dump air outflows, including soil covers, toe drains, and water sampling pipes, but also include coarse rock channels formed naturally during dumping, finer rock layers formed by traffic or regarding, and localized excavations into the dump toe.
  • Any factors that serve to limit the mixing of out-flow air gasses with the surrounding air, including monitoring stations but also any other walls of berms, heavy vegetation, and local ground depressions, as well as barometric inversion or similar weather conditions that cause pockets of air to accumulate in depressions.

Although the above risk factor are stated in terms of waste rock dumps, some of them may be present in tailings dams, tailings piles, ore stockpiles, and other site components. At this time the Technical Panel is not limiting possible affected areas to those confined by a structure. It is possible that open areas, such as a low-lying on a calm day or a sheltered ravine at a dump toe, could harbor impacted gas that poses a risk. The Technical Panel recommends that mine sites conduct risk assessments of site components where these factors may be present and use the findings to develop safe work procedures.”