A heating oil tank attached to a portable at Vanier Catholic Secondary School leaked its entire contents on Sunday night.

Firefighters were called to the scene at approximately 6:45 p.m., but were too late to do anything about the spill. The oil had already soaked into the earth, leaving a large five-metre puddle in the earth outside the high school.

The students who normally attend class in the portable have been relocated during the clean-up process, said Vanier vice principal Ryan Sikkes. A variety of different classes are taught in the portable.

The area was fenced off by Monday morning and a sign in the doorway instructed students their classes would be held elsewhere.

Bryan Levia, a manager at Environment Yukon, said the spill was caused by a cracked supply line in the tank.

Karla Ter Voert, communications analyst for Highways and Public Works, said they suspect the crack was caused by vandalism. It appeared to have either been kicked or stepped on.

Levia did not know the extent of the spill, but the tank has a capacity of 1,363 litres (300 gallons). Crews will have to check fuel records to ascertain how full the tank was at the time of the leak.

Levia said that as long as students are kept away from the spill, it poses no immediate danger. He could not estimate how long it will before the students can return to their regular classes in the portable.

Levia said the spill was further complicated by the fact the spill leaked underneath the portable. He said the portable may have to be moved during the cleanup process. Crews will have to delineate the contamination, mapping its horizontal and vertical movement.

The contaminated earth will then be removed and sent to a land treatment centre. They will then have to test the area and demonstrate that it is free of contaminants.

The affected area will later be backfilled with clean soil.

Crews were working on cleaning up the spill on Monday morning, and Levia said he could not estimate how long the cleanup will take or how much it will cost.

"Every situation is different and has unique circumstances,” he said.

EBA Engineering Consultants Ltd. has been hired to spearhead the cleanup process.

Ter Voert said the government's primary objective is the remediation of the spill, and once that is finished they will focus on avoiding these spills in the future.

"Our question is: How do we stop something like this from happening in the future? We're looking at ways to reduce the possibility of an accident like this happening in the future,” she said.

They have installed temporary heating devices in the unaffected portables.

The Yukon government will ultimately pay for the clean up costs associated with the spill, said Levia.