Marwell tar pits cleanup expected to take years

Slowly but surely the Marwell tar pits in Whitehorse are getting cleaned up.

Slowly but surely the Marwell tar pits in Whitehorse are getting cleaned up.

The first phase of the project is well underway, but it’s a big job that’s going to take years to finish, said Rick Seaman, who is in charge of the cleanup for the Yukon government.

“The first phase will be basically looking at the site, doing all the gap analysis to determining what we know about it and then building a plan to find the rest out,” he said. “Once we have a full site assessment done, from that we’ll be able to come up with some of the cleanup options.”

And there are a lot of those.

“I’ve seen 14 different options presented,” said Seaman. “Everything from simply mixing it with cement and leaving it there to digging a big hole and hauling it away.”

And there are a lot of options between those two extremes.

The contaminated soil could be used to make asphalt, it could be burned for energy, or it could be bio-remediated using bacteria and microbes to break down the toxins.

Back in 1993, the federal government hired TriWaste Treatment Services to study the feasibility of cleaning up the soil through thermal desorption or boiling off the hydrocarbons.

TriWaste cleaned about one per cent of the approximately 27,000 cubic metres of soil.

A biological treatment process was also considered at the time.

The price tag for either option was estimated to be between $3 million and $4 million, but in the end, nothing was done.

“Basically what it came down to was nobody was found to be responsible for the site,” said Seaman.

It wasn’t until 2010 that an agreement was struck between the federal and territorial governments.

The 10-year remediation project is expected to cost $6.8 million.

The federal government agreed to provide 70 per cent of the funding with the territory kicking in the rest.

It’s been a long time coming.

The Marwell tar pits date back to the 1940s.

Originally, the site had an oil refinery, built by Standard Oil under contract with the U.S. military. In the late 1940s the refinery was bought by Imperial Oil, dismantled and moved to Alberta.

But it didn’t take everything.

“When they took apart the refinery, they scraped the bottoms of all the tanks, threw everything into the retaining berm,” said Seaman.

In 1958 a man walking through the area got trapped in the tar and died of exposure.

It was the only documented death at a contaminated site in Canada.

A coroner’s jury at the time strongly recommended the oil pool be removed as soon as possible. Instead, the site was covered up with clay.

It wasn’t until 1989 that Environment Canada started to seriously investigate the site.

“Of course, technology has changed a lot in 20 years, and the site characteristics have most likely changed a bit over time,” said Seaman. “We’re just trying to get a real good handle on it now. I think at the end of the day the most appropriate option will be a balance of cost versus effectiveness.”

Contact Josh Kerr at

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