Syncrude readies for historic ‘retirement’ of dam

It’s a “retirement” nearly 10 years in the making after almost 40 years of service. And it marks a significant milestone for Syncrude and the oil sands industry.

Syncrude has submitted the closure completion report for Coke Cell 5 (CC5) to the Alberta Energy Regulator (AER). Once accepted, Syncrude will remove CC5 from its list of dams.

“These dams are regulated by the AER because they retain fluids and tailings,” says Glen Miller, an Associate Geotechnical Engineer, Regulatory & Lease Development. “We have about 20 fluid-retaining structures on the AER’s registry. Once they are no longer required, we design and implement our closure plan then apply to remove them.”

What will make CC5 different than other dams in the oil sands is it’s the first-ever tailings facility reconfigured into a permanent, reclaimed landform that will be de-registered.

“We’ve had other dams de-registered, but they were in-pit structures submerged under water or tailings,” Glen says. “We are not burying CC5. We’ve physically modified it so it can be regulated in the same way as an inactive overburden dump. It is already revegetated and will eventually be ready to achieve a reclamation certificate, just like Gateway Hill.”

Construction began in 1985 on CC5, a ring dyke built with overburden to hold petroleum coke hydraulically poured into it. Syncrude completed the infilling of coke in late 1999. Ten years later, the AER approved Syncrude’s detailed closure plan showing the modifications required to close CC5, which covers an area of 170 hectares on the north shore of Base Mine Lake.

“After getting approval of our detailed closure plan, it took four years to complete the work, which included the excavation of an outlet in CC5’s southwest corner and recontouring a plateau into a shallow valley that drains environmental runoff towards that outlet,” Glen says. “We submitted the closure completion report in December 2020 and held a thorough field tour of CC5 with the person reviewing the submission for the AER in June. Now we’re just waiting to hear back from the AER soon and are very excited. This will be a significant milestone for Syncrude and for the industry.”

While many people were involved in the shepherding of CC5 towards this historic milestone, Glen singled out a couple key contributors.

“Wayne Mimura, who oversaw each step of this submission, from initial development to final review, as Senior Geotechnical Advisor and Engineer of Record for CC5. And Jack Law, as the Regulatory Affairs Advisor responsible for CC5, served as the point person with the AER and guided the submission’s scope,” Glen says.

As with many of successes here at Syncrude, collaboration helped fuel the success.

– Glen Miller

And Glen, who serves as Syncrude’s closure designer, expects to see the closure of tailings facilities become the norm in the coming decade.

“Folks should look forward to seeing this become routine. We’ve got a few in progress at Aurora and Mildred Lake sites. The East In-Pit detailed closure plan was submitted to AER this past June and we are currently in the process of developing a similar submission for South West In-Pit and then Base Mine Lake is next. To see these closure and reclamation projects accelerate in the areas where we first starting mining in the 1970s, it’s really rewarding to be a part of the final chapters that conclude our use of this land.”

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