07/18/2015 03:11 EDT | Updated 07/18/2016 05:59 EDT

Nexen Pipeline Spill in Northern Alberta Under Clean-Up Order From Regulator

EDMONTON - The clean-up of a pipeline spill south of Fort McMurray is underway, but the cause of the contamination has yet to be confirmed.

Vacuum trucks were on site Saturday and fencing went up to keep wildlife away near Nexen Energy's Long Lake oilsands facility, said Kim Blanchette, a spokesperson for the Alberta Energy Regulator.

However Blanchette could not say what caused the breach in the double-walled pipe that spilled five million litres of oil emulsion into the area around the line.

"It's still very early in the process," Blanchette said in an interview from the spill site, about 35 km southeast of Fort McMurray.

"The important piece now is really containing the area and making sure all of those preventative measures are in place while they're actually excavating that piece of pipeline so that the investigators and their forensic work can begin."

Emulsion is a mix of oil, water, and sand.

The affected area is about 16,000 square metres.

There are no homes in the immediate area. The closest community, the hamlet of Anzac, is 15 km north of the spill site.

Blanchette said the regulator has delivered to Nexen Energy an environmental protection order.

The order formally directs Nexen to clean up the spill, notify affected parties, monitor the impact and deliver a long-term plan to return the affected area to its natural state.

Officials with Nexen Energy, a unit of China's CNOOC Ltd., declined an interview request but updated the clean-up progress on its website.

Nexen said that over the weekend crews will continue the clean up while finishing the fencing and erecting other wildlife deterrents.

The company will also begin surveys and tests to determine the extent of the spill and the environmental impact.

The spill was spotted Wednesday by a contractor after the company's automated monitoring system failed to report the breach.

On Friday, Ron Bailey, Nexen's senior vice-president of Canadian operations, said the company was investigating the system failure and apologized for the impact of the spill.

Coincidentally, the rupture made headlines as Alberta Premier Rachel Notley talked with fellow premiers and territorial leaders in Newfoundland about energy issues and the proposed Energy East pipeline, which would transport Alberta bitumen to New Brunswick.

Notley said her government will make sure all questions surrounding the rupture are answered, but said pipelines continue to be the safest way to carry oil and gas across the country.

The Nexen rupture comes just a few months after Murphy Oil spilled about 2.7 million litres of condensate at its oilfield in northwestern Alberta in March.

Condensate is used to dilute heavy oil so it can flow through pipelines.

In 2011, about 4.5 million litres of oil leaked from a Plains Midstream pipeline into marshlands near the northern Alberta community of Little Buffalo.

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