Broad Category: Features

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.”

“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.

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.

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.”

And much of the monitoring and research by scientists have charted the progress within the lake, right down to the tiny microbial communities that inhabit the 800 hectares of water (Micro-organism ‘hunter’ sees signs of progress in Base Mine Lake’s microbial communities).

Given the amount of research into water-capped tailings management technology since the early 1980s, it was unsurprising to see Syncrude turn to technology to solve the issue of oil sheens on the lake’s surface.

“Residual bitumen from extraction makes up a small portion of fluid fine tailings (FFT). When we placed the FFT into the pit that now forms Base Mine Lake, some of the bitumen was liberated, resulting in mats that formed in two corners of the lake,” says Brandon Kremp, a mining engineer in Tailings & Lease Development. “The initial filling of the pit and the bitumen mats have resulted in a hydrocarbon sheen on the surface and bitumen coating along the shoreline.”

“We pumped that material into a nearby holding pond in 2018 and 2019,” says Brandon, who joined Syncrude in 2019 after starting as a co-op student three years earlier. “Syncrude had used that technology to transfer materials being holding ponds for several years but it didn’t work as well on the bitumen mats due to the viscosity of the material.”
A team began researching alternatives and came up with another solution, an underwater mechanical excavator that could scoop material from the tailings bed.
“We began using this method when we started dredging in the middle of August and will use it until the end of the season, which typically comes near the end of October when the lake starts to freeze over,” says Sebastian Lastra Valenzuela, Team Leader, Mildred Lake Tailings Planning.

Every operator has this type of lake in their closure plan and we are proud to be the ones pioneering it.”

As with proving any ground-breaking technology, the team has faced some challenges. “But we’ve learned from them and are gratified to see the result of a lot of hard work. We are at the very early stages but the technology is showing real promise,” says Sebastian, who joined Syncrude in 2014.

And the success to date has many authors as collaboration with other business units, including Research & Development, Tailings & Lease Development – Expense Projects and Operations – helped Sebastian’s team unlock the solutions.

“There’s a lot of people who deserve to share the credit for driving this project forward, including Keith Baker, Sandra Armstrong and Robert Trettenero,” says Sebastian. “Our work has also been strongly supported by Trevor Finlayson, Barry Bara, Dallas Heisler and Carla Wytrykush.”

Beneath that water and surrounding landscape, close to 40 years of research has gone into the lake, a demonstration project of Syncrude’s water-capped tailings technology to turn a former mine pit and tailings pond into a lake capable of supporting aquatic plants and animals.

“Syncrude and its researchers have earned more than 240 patents but we have just one to show for all the research put into the water-capped tailings technology. That’s primarily because we are sharing our intellectual property on our reclamation technologies publicly,” says Mal Carroll, Syncrude’s Manager – Research & Development. “Six universities have conducted research on Base Mine Lake’s progress as part of a very extensive research and monitoring program and they share their findings through peer-reviewed papers. We also share what we’ve found with our industry partners through organizations such as Canada’s Oil Sands Innovation Alliance as well as post that research online.”

Those findings convinced Syncrude to move ahead with Base Mine Lake, a former tailings pond in the original Base Mine, located just south of the Mildred Lake upgrading complex west of Highway 63. Syncrude stopped pouring in fluid tailings at the end of 2012 and began adding fresh water from the Beaver Creek Reservoir, and mine process water in 2013. The lake now covers 800 hectares with about 45 metres of fluid tailings. The tailings were capped by five metres of water, and with dewatering the water cap is now up to 12 metres deep. Syncrude, the University of Toronto (Water is in her blood), McMaster University, University of Alberta, University of Calgary, University of British Columbia and the University of Saskatchewan have conducted research and monitoring on Base Mine Lake to chart the progress in several different areas, including, dewatering of the underlying fluid tailings layer and water chemistry.

The fluid tailings are dewatering. Researchers are tracking changes in the water, right down to the microbial level (Micro-organism ‘hunter’ sees signs of progress in Base Mine Lake’s microbial communities),” says Mal. “We’ve made a lot of progress but recognize there’s still work to be done. And going forward, we will continue to have science guide us, just as we have over the previous four decades. And we will continue to share our findings with the public, particularly the Indigenous community members who have visited Base Mine Lake and want to learn more about it. Patents are nice but transparency is very important with this project. We want people to know we are getting this done the right way.”

“Water is prized given the prominence of farming where I grew up,” says Dallas, Syncrude’s Pit Lake Co-ordinator. “But we also recognize the value of water in the Wood Buffalo region. While agriculture isn’t a major industry here, the lakes, rivers and wetlands are very important. People want them to be protected. That’s no different than back home.”

Syncrude is bringing those values to managing Base Mine Lake, the demonstration project for its water-capped tailings The lake, which covers 800 hectares just south of Syncrude’s Mildred Lake upgrading complex, was a former mine pit prior to being a tailings pond.

“Syncrude completed tailings infilling at the end of 2012 and began importing fresh water from the Beaver Creek Reservoir starting in 2013 so there is now approximately 40 metres of fluid tailings covered with about 10 metres of water,” says Dallas. “Researchers from Syncrude (Medical equipment helps solve Base Mine Lake monitoring mysteries) as well as several universities, including the University of Toronto (Water is in her blood) and the University of Calgary (Micro organism hunter sees signs of progress in Base Mine Lakes microbial communities) have monitored the progress of Base Mine Lake since then. What they’ve found is the fluid tailings are dewatering, which reduces their volume. We’re also seeing promising changes in the water quality, which is in line with the 40 years of previous research we’ve done on water capping.”

“The inflow comes from the Beaver Creek Reservoir from the south. Right now, the outflow water is returned to Syncrude’s recycle water system,” Dallas says. “While the goal is to eventually have the lake flow out to the Athabasca River, we need to store that water on site at the present time until the federal governments establish regulatory criteria for treated mine water into the environment.”

Syncrude is working on demonstrating two technologies – water-capped tailings technology and coke-treatment (Warren’s innovation will help reclaim tailings ponds faster. – Syncrude) to eventually allow the release of mine water into the environment. Those releases are anticipated to be managed consistently with other releases approved from other industries in Alberta and Canada. Until then, all water – including Base Mine Lake’s outflow – must remain stored on site. “We are operating close to our capacity for mine water and tailings so we are looking at all options as we do not want to build a new tailings facility,” Dallas says. “As a result, we have decided not to bring in fresh water from Beaver Creek Reservoir to Base Mine Lake for this year. It is the responsible thing to do in order to manage our water inventory on site.”

The extensive monitoring program will continue to track changes within the lake through the year to determine how the change in water inflow influences Base Mine Lake’s performance.

“We’ve tied this into all the work being done on the monitoring and research. We’ll continue collecting samples and getting researchers out on the lake and reporting those findings.”