Sunrise Propane had a lawyer plead not guilty on its behalf at a long-awaited trial that began Monday, more than three years after the company’s facility in northwest Toronto exploded, killing a worker and forcing thousands to flee their homes.

Sunrise employee Parminder Saini died in the explosion and firefighter Bob Leek suffered a fatal heart attack while battling the fire that followed. The blast sent up a fireball that could be seen across the city and forced the evacuation of 12,000 people from their Downsview neighbourhood homes.

The company faces several charges under provincial labour and environmental laws for its role in the Aug. 10, 2008, explosion that changed the lives of those who live near the fuel depot at 62 Murray Rd., in the Keele Street and Wilson Avenue area.

Company, directors plead not guilty to all charges

At the start of the trial, defence lawyer Leo Adler pleaded not guilty to all of the charges on behalf of the propane company and two of its directors.

CBC's Genevieve Tomney said that government lawyers laid out the case they intend to present in court, which will include testimony from a Sunrise employee who survived the blast.

Prior to Monday’s proceedings, Adler said he hoped the trial would show that the explosion was an accident and not the result of negligence.

"By the time this case is over, people will understand that what occurred was a tragic accident that was due to a defective part," he said.

Sonia Cool, whose father's house was destroyed in the explosion, said it's important that residents affected by the blast get their day in court.

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Vic Viani says he and his wife would have been killed if they were home when the propane explosion occurred.

"There's no monetary value for [what] these poor residents went through," she said. "And for that reason, we hope they get what they deserve."

Vic Viani is one such survivor who lived in a house directly across the street from the blast and flames.

He was fortunate to be out of the house when the explosion occurred.

If he had been home, he and his wife "would have been killed for sure," Viani told CBC News on Monday.

Illegal truck-to-truck transfers

An Ontario Fire Marshal’s report into the explosion found that an illegal "tank-to-tank" transfer was underway at the time of the explosion and that a propane leak resulted from a hose failure. The ignition source of the blast has not been identified.

The report noted that tank-to-tank and truck-to-truck transfers are both dangerous and illegal in Ontario. Sunrise had been warned about the practice prior to the explosion.

Cleaning up the site cost more than $2 million.

"The company's directors are facing a lot of questions," CBC's Philip Lee-Shanok reported Monday. "A lot of people are watching what happens today, not just because there's about $1 million in fines — there's also hundreds of millions of dollars in outstanding class-action lawsuits."

The trial is expected to last about six weeks.

With files from CBC's Genevieve Tomney