An expert on hazardous material spills has called the Lac-Mégantic train explosion "the worst environmental disaster in Canadian history."    

Rosa Galvez, chair of the civil water engineering department at Laval University, said digging at the site of the blast shows the soil there is completely saturated with oil.

“They ran hundreds of trenches and they saw free petroleum coming and filling up the trenches,” said Galvez.

A preliminary report on the extent of the contamination was released yesterday by the Montreal-based Golder company, stating that more than 100,000 cubic meters of soil will have to be excavated at the site of the derailment.

The report, made public Monday, is based on an investigation conducted by Golder between July 7 and Aug. 20.

Golder was initially hired by the Montreal, Maine & Atlantic Railway, owners of the train that crashed in Lac-Mégantic.

Golder now works for Pomerleau Inc., which is overseeing cleanup operations.

On July 6th, a train towing dozens of tanker cars derailed in the town, killing 47 people and releasing roughly 5.5 million litres of oil that either burned or leaked into the environment.

Galvez said pollutants have saturated several metres into the ground, with levels are so high, people will not be able to live there until it's decontaminated.

She said the amount of soil that has to be treated could even increase.

“In the report they recommend that they should extend monitoring to other areas to see if there are other volumes of soils to be treated,” said Galvez.

Galvez estimated the base cost of decontamination could be anywhere from $30 to 50 million.