Marwell Tar Pit remediation project

The governments of Canada and Yukon are funding the assessment and remediation of the Marwell Tar Pit in Whitehorse, Yukon's largest single-source hydro-carbon contaminated site. The field work for the $6.8 million project began in 2011.

Remediation will help protect the environment from contaminants at the site and safeguard the health and safety of people. The Department of Environment’s Site Assessment and Remediation Unit is responsible for co-ordinating the project, which is scheduled to be completed in 2020-21.

The Marwell tar pit site is fenced off and posted. It is less than 500m from Two Mile Hill, at the foot of the Takhini East bluffs.

Assessment and remediation is being done in three phases:

The project is now into the second phase. The remediation is using enhanced thermal conduction to treat contaminated soil. It is a process that heats the soil and vaporizes the contamination. Vapours are captured and destroyed through burning that meets air quality standards. It leaves just carbon dioxide and water vapour behind. This phase is expected to be finished in 2019-20.

Nature of the contamination

Government began monitoring the site in the 1970s. Initial investigations in the early 1990s found that hydrocarbons had contaminated an estimated 27,000 cubic meters of soils as well as the groundwater. Some of the ‘tar’ had migrated from the site as well.

The hydrocarbon contamination includes: benz[a]anthracene, heavy and light extractable petroleum hydrocarbons and naphthalene; other contamination includes heavy metals such as manganese. The concentrations of these contaminants are well above the industrial standards set out in Yukon’s Contaminated Site Regulation.

History of the tar pit site


The tar pit’s origins date back to the Second World War, when an oil refinery was built in what we now call the Marwell area to process crude brought by the Canol Pipeline from Norman Wells, NWT. The refinery operated for less than one year before closing in March 1945.

Marwell Tar Pit refinery in operation

The refinery, storage tanks, crew camp and rail lines occupied the entire Marwell area. A total of 866,670 barrels of product were produced in all.

After the war ended, the refinery was dismantled and shipped south. Many storage tanks were dismantled as well. The sludge from the bottom of these tanks – or ‘tar’ – was deposited in a tank berm on the far west of the area. (The tank on this site had also been dismantled, with only the dirt wall [berm] that surrounded the base remaining.)


For many years, Whitehorse businesses and individuals added used oil and other liquid wastes to the tar pit. In the early 1960s, the gooey pit was capped with gravel. The Government of Yukon declared the tar pit a ‘Designated Contaminated Site’ in 1998 under the Environment Act. Signs were posted to warn people away from the site


The governments of Canada and Yukon completed an agreement in June 2010 for funding the assessment and remediation of the tar pit site. Funding comes from the Federal Contaminated Sites Action Plan and the Northern Strategy.


The Yukon government is responsible for carrying out the project, ensuring all activities meet the regulatory and licensing requirements called for under the Yukon Environmental and Socio-economic Assessment Act and the territory’s Environment Act.

Additional resources


Contact Site Assessment and Remediation Unit
Phone: 867-667-8271
Toll-free (in Yukon, NWT & Nunavut):
1-800-661-0408 ext. 8271
Fax: 867-456-6124

Email: envprot@gov.yk.ca
Address: Box 2703 (V-8) Whitehorse, Yukon Canada Y1A 2C6