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Explosives expert knew nothing of nearby houses, court told

Paula Armstrong was outside her Lobird subdivision trailer when she heard the explosion. She had bent down to pick up a piece of garbage from the road.

Paula Armstrong was outside her Lobird subdivision trailer when she heard the explosion.

She had bent down to pick up a piece of garbage from the road. When she looked up she saw a cloud of dust, dirt and rock rise up out of the woods.

At first she watched the spectacle with awe, as if it were a fireworks display.

Then she noticed the wave of rocks coming in her direction.

Armstrong jumped for cover and watched four sharp, small rocks land where she had been standing just moments before.

A larger stone slammed to the ground directly to her left.

Hunks of granite rained down all around her, some as large as 22 kilograms, slamming into trailers, sheds and fences.

One stone crashed through the ceiling of trailer 212, landing less than a metre away from where the Carpenter family was sitting as they watched TV.

Another rock slammed through a tin shed, finally coming to rest in a woodpile on the opposite side.

Remarkably, no one was seriously hurt.

The botched blast, which occurred on May 6, 2008, was conducted as part of the Hamilton Boulevard extension project.

This week, those responsible for the roadwork are in court to decide who was responsible for the hazardous incident.

This includes the Yukon Government’s Community Services branch, which was in charge of the project.

The other two defendants are the contractor, Sidhu Trucking Ltd., and Bill Cratty, the supervisor of the site at the time.

The court heard from a number of witnesses on Monday and Tuesday, including Armstrong who described what it was like to live through the incident.

Peter Hildebrand, the blaster who conducted the May 6 blast, also took the stand.

Hildebrand, who has already pled guilty and been fined $1,000, testified that he had no idea how close the subdivision was that day nor during the 18 previous blasts he conducted for the project.

In the blast proposals, which he was required to complete and give to a Yukon government representative prior to each blast, he often wrote “n/a” as the distance to the nearest structure.

When he did write in a distance, it was often based on no more than a guess, he told the court.

In the proposal for the May 6 blast, Hildebrand estimated the distance to be about 400 metres.

In actuality, it was a mere 150 metres to the closest home.

The Carpenter’s trailer was 166 metres from the blast site.

Hildebrand wasn’t shown an aerial map of the area and thus wasn’t aware how close the project was to the subdivision, until after the incident had occurred.

Hildebrand has 50 years of experience as a blaster and believed that he was doing everything possible to have a safe blast, he said.

However, he did not use blast mats.

Blast mats are made up of heavy-duty truck tires, flattened and wired together.

If used, these mats can greatly reduce the risk of large fly-rock during the blasting.

The mats were available on site, although there were not enough to cover the entire blast area.

The May 6 blast was the largest of the project, with over 400 holes drilled and packed with explosive.

The mats were not used because they’re cumbersome and can sometimes create more problems than they’re worth, said Hildebrand.

The heavy mats, which weigh nearly three tonnes, can crush or puncture the lead wires, causing some holes to fail to detonate and creating a very dangerous mess for workers to clean up.

Sand and clay can also be used to prevent fly-rock and had been used in previous blasts on the project.

However, they were not used on May 6.

On Tuesday, Hildebrand was asked whether he would have conducted the blast any differently if he were to do it again.

If he’d had proper knowledge as to how close the subdivision really was, he would never have conducted the blast, he said.

As much as 98 per cent of the blast went perfectly, according to Scott Parker, a blasting expert that was brought in to investigate the incident.

He suspects that only two of the over 400 holes had misfired.

The fly-rock could have been caused by a particular low-lying area, Parker told the court.

A couple of the holes in this area were only 1.2 metres deep, which makes them very difficult to manage.

The blaster should have realized that these holes had a high chance of malfunctioning, he said.

The fly-rock could also have been caused by natural cracks in the stone, which are impossible for a blaster to know about.

However Parker was careful to note there is really no way of knowing what happened that day.

“There are no guarantees in this game,” he told the court.

“We’re dealing with high explosives and it’s impossible to tell exactly what’s going to happen. Even the most skilled and careful blaster can’t create a perfect blast all of the time.”

It would have been reasonable for Hildebrand to know where the subdivision was, Parker told the court.

“But there should have been someone tapping him on the shoulder, telling him, ‘Hey, it’s just over there!’”

Someone should have provided him with that information, especially the government site inspector who was reviewing Hildebrand’s blast proposals, Parker added.

The court also heard from Leah Battersby, who lives in trailer 23 and reported a similar problem with blasting that happened four months before the May 6 explosion.

In early November 2007, Battersby returned to her home to find a fist-sized hole in her ceiling and smooth round rock on the floor.

At first she thought it might be a meteor.

Then she deduced that it must have had something to do with the road extension project nearby.

She contacted her father who then contacted the managers of the project.

Representatives from both government and Sidhu came to the house to inspect the home and later paid for repairs.

However, extra caution was not exercised after this occurred.

The court also heard that, although the incident occurred a 7 p.m. on May 6, the Workers’ Compensation Health and Safety Board was not notified immediately, as is required by regulations.

A call to the board wasn’t made until 10 the following morning.

The trial looks set to continue well into next week.

Contact Chris Oke at