TORONTO (miningweekly.com) – Alberta’s medical chief on Tuesday said that the plume of mine wastewater floating down the Athabasca river following a containment pond failure, posed no immediate health threat to humans.

On the evening of October 31, a dyke failure on the defunct Obed Mountain mine site, in the Hinton region, caused the release of about 670-million litres of process water and suspended sediments into the Apetowan and Plante creeks, which merge into the Athabasca river downstream of Hinton.

“I am confident that at no time was there a risk to the public’s drinking water. As chief medical officer my primary concern is that proper procedures are followed and that the water the public is drinking is safe. While there was a temporary increase in some contaminants, those levels are returning to normal,” Alberta’s chief medical officer of health, Dr Jim Talbot, said.

Water quality results from ongoing sampling of the Athabasca river indicated no immediate risk to human health; however, it did find that health and environmental water quality guidelines were exceeded for some parameters within 40 km of the release.

Among the contaminants found were aluminium, manganese, lead, cadmium, mercury and known cancer-causing compounds.

Alberta Environment and Sustainable Resource Development (ESRD) said the Apetowan and Plante creeks received the direct volume from the mine site and sustained significant impacts particularly within the first 4 km nearest the mine.

The Plante creek is a fish-bearing stream and the Athabasca river is a source of water for many communities, businesses, agricultural, industrial and private users, as well as a significant fishery in the region.

On November 1, the Alberta government warned downstream communities not to draw water from the Athabasca river, and treatment plants were told to avoid using the river when the plume was passing through their areas.

PROTECTION ORDER

The ESRD on Tuesday also issued an environmental protection order to Coal Valley Resources and Sherritt International, compelling the companies to clean up the spill.

The order required Sherritt to immediately take steps to contain the mine wastewater solids remaining in the two Athabasca tributaries and prevent any further solids from entering the Athabasca river; to undertake measures to recover the mine wastewater solids in Plante creek where it meets the Athabasca river; and to develop and implement a comprehensive sampling and monitoring plan.

The ESRD said that as a precaution, community water treatment plants would continue to refrain from using the Athabasca river when the plume is near, and residents were reminded not to consume raw, untreated river water at any time, regardless of the sediment plume.

Determining the full extent of the release on the ecosystem of the Athabasca river would require long-term monitoring.

“We’ve implemented an intensive sampling programme and we are working closely with experts at Alberta Health, Alberta Health Services, and other agencies. Determining the full extent of impacts to the ecosystem will require long-term monitoring and ongoing partnership with cross-government experts,” ESRD limnologist and water quality specialist Dr Colin Cooke said.

The government of the Northwest Territories said it was expecting the plume to arrive at Lake Athabasca between November 29 and December 3. Should flow rates remain the same, the plume could enter the Northwest Territories between December 7 and 10. Monitoring the plume movement in the Athabasca river was currently being done by helicopter.

“Currently, there is no cause for concern about the spill in the Northwest Territories. We are continuing to track the spill and are making preparations for monitoring in the Northwest Territories should, or when, the plume moves into the Slave river,” Environment and Natural Resources Minister Michael Miltenberger said.

Sherritt Coal said it was working with regulators to ensure the restoration of the areas of the Apetowun and Plante creeks most directly affected by the sediment.

“We began our testing the morning after this happened and, to date, these samples have indicated that the sediment travelling downstream in the Athabasca river poses no risk to human health or safety. We are also continuing to monitor the effects this release has had on the Athabasca river,” Sherritt senior VP for coal Sean McCaughan said.