Conditions leading to Sullivan mine site deaths were unprecedented, says BC chief inspector
The deaths of four people at the decommissioned Sullivan mine near Kimberley, British Columbia last May resulted from a series of unprecedented circumstances, BC's chief inspector of mines has concluded. An oxygen-depleted atmosphere inside a water sampling shed at the mine site claimed the lives of Doug Erickson, a Pryzm Environmental consultant working for Teck Cominco, Bob Newcombe, an employee of Teck Cominco, and BC Ambulance Service paramedics Kim Weitzel and Shawn Currier (EcoWeek May 22, 2006).
"The incident was caused by an oxygen-deficient atmosphere. However, previous to this incident, there was no indication of a problem at the sampling shed or anywhere on the mine site," said chief inspector Fred Hermann. "We have clearly established the cause of death of the four victims, but this accident is unprecedented in the history of mining and the process that led to the oxygen-depleted atmosphere has not, to our knowledge, occurred anywhere else in the world."
The chief inspector's final report found the direct cause of the accident to be an accumulation of oxygen-depleted air within the shed, in particular in the sub-level excavation in the structure. This air mixture was unexpectedly transported from within the dump, entering the shed through a drainage pipe installed to direct water from a covered collection ditch to a treatment facility.
The report notes that oxidation of the rock within the dump (a natural process) had altered its atmosphere. This process consumes the oxygen content of the atmosphere, leaving carbon dioxide as a byproduct. The resulting air mixture is heavier than air and would naturally accumulate lower in the dump, the report continues.
Reclamation activity recently completed at the site had included construction of a rock drain at the toe of the dump. This was designed to direct water flows from within the dump to a collection pipe running into the sampling shed and ultimately connecting to a downstream treatment facility. The piping systems had been in place for several years and the rock drain was "very substantial," says the report. In addition, the entire surface of the dump, including the rock drain, was covered in 2005 with a one-metre-thick layer of glacial till whose high clay content rendered the site cover relatively impermeable.
The report says the mechanism by which the air mixture was transported has yet to be conclusively determined. The shed had been in use for several years and had been accessed safely a recently as the week before the May 15-17 incident. It is noted that daytime temperatures for several days preceding the event had been extremely hot (over 30*C). These temperatures, coupled with the presumed cold temperatures within the dump, may have resulted in the air flowing from the dump out to the rock drain and then through the pipe.
Because there had been no prior indication of a hazard at the sampling shed, Erickson and Newcombe had no reason to be concerned about a potentially hazardous environment when they entered the shed, the chief inspector says.
Paramedic Kim Weitzel entered the shed with the understanding that she was responding to a drowning. On her way down the ladder she questioned the presence of gas, but even by that time it was too late for her to extricate herself. The report further cites lack of basic hazard recognition training and experience as a factor contributing to the loss of Weitzel's partner Shawn Currier, who entered the shed to render assistance immediately after she was overcome.
Immediately after the incident, the chief inspector of mines ordered interim measures relating to the identification of hazards downstream from dump sites, to ensure that a similar event could not happen at any other mine site in the province. These directives will remain in place, and the chief inspector's report makes additional recommendations relating to the Sullivan mine site itself, other BC mine sites, non-mine site emergency responders and the BC Ministry of Energy, Mines and Petroleum Resources.
With regard to the Sullivan mine site, the report recommends, among other things, that workers entering confined space environments downstream of waste dump sites are qualified in air sampling (or are accompanied by someone so qualified), and that proper samples are taken and a safe atmosphere determined before entering these environments. A monitoring program should be developed and implemented to determine the mechanism by which the atmosphere is mobilized from within the dump out to the sampling shed, it adds.
The chief inspector has also recommended that his directives issued following the Sullivan mine incident relating to identification of hazards downstream from dump sites be implemented by all mine sites in BC. Mine managers should also be required to provide information about possible site hazards, and the likelihood of encountering such hazards, to off-site emergency responders with entering into agreements with these responders.
Finally, the report recommends that the requirements of the chief inspector's directive issued after the Sullivan mine incident be incorporated as regulations within BC's Health, Safety and Reclamation Code (HSRC). The inspector calls for an addition to his directive requiring that any opening with the potential to act as a conduit for the transport of a hazardous atmosphere from within a mine waste dump be tested to ensure that the atmosphere at the mouth of the opening is safe.
As a follow-up to the completed report on the incident, research and modeling will be conducted to determine why the shed had an oxygen-depleted atmosphere. This will include simulating the temperature and atmospheric conditions present during the incident in the sampling shed in May 2006. Results will be released in the fall of 2007.
The chief inspector's report was immediately accepted by BC Minister of State for Mining Bill Bennett. "I accept the chief inspector of mines' report and its findings and support his recommendations to ensure the safety of workers and first responders at mine sites," he stated.
Teck Cominco said it has also reviewed the report and has already implemented many of the chief mines inspector's recommendations.
"The report has been provided to all of our operations and we are committed to working closely with the appropriate agencies to ensure the recommendations are implemented so that this type of accident will never happen again," said company president and CEO Don Lindsay.
The report may be viewed on the Ministry of Energy, Mines and Petroleum Resources Web site, www.gov.bc.ca/empr.