Underground safety

While big firms have systems, smaller generals could be struggling to work safe

The combination of booming economy and skilled labour deficit has hit just about every sector, including excavation and underground construction. The shortage of experienced people and spiraling demand for services has resulted in expertise being spread more thinly. Besides work quality and productivity, this can also affect safety. "You need people who are able to identify a hazard. Because of skills shortages, it becomes a struggle for companies to keep people trained and knowledgeable in hazard identification," says Mark Kondro, the safety and personnel manager at Standard General's Calgary office.

Large road building and paving contractors like Standard General, however, partly because of their size and specialization in work that includes a lot of excavation and trenching, have a range of safety programs in place such as daily hazard assessments to prevent mishaps. Kondro says he can't remember the last time a serious accident or fatality occurred on a Standard General work site.

In other sectors, however, it's a different story. In much commercial, industrial and residential construction, the safety focus, understandably, is often more on preventing falls, which are the commonest cause of serious injuries on construction sites. The result, says Kondro, is that it can sometimes be a challenge for smaller construction outfits that perform a wide range of tasks, most of which are above ground, to be up to speed in hazard assessment when it comes to excavation and underground work. "Without training, people in unsafe situations with a trench don't know what the hazards are," says Kondro.

A cave-in on a site in Edmonton on the last weekend of October this year may have dramatically highlighted this last point. Two workers, including a 16-year-old boy who was buried over his head, were rescued after more than three hours trapped in a collapsed trench. According to one account, published in the Edmonton Journal on Monday, October 31, the accident involved a hole, estimated at about two metres deep, that had been excavated under a concrete patio, apparently with no shoring.

A third worker on the crew had seen the cave-in happen and, after calling 911, had managed to dig an air hole down to where the teen was. The crew had been excavating along the wall of a five-story seniors residence prior to repairing a leak. Water had been seeping into the underground parking area of the two-year-old building.

The worker who performed the rescue commented on how fast the cave-in happened and was reported to have said, "We didn't have it shored up at all. I have never done this kind of work before." A roofer by trade, he had come to help out for a few hours.

Kondro points out that a cubic metre of dirt can weigh about two tons, or, if loose, "maybe 1.5, 1.6 tons." The more tightly packed the cave-in material is, he notes, the greater the chance of suffocation, because "if the person's chest can't expand, they can't breathe."

Companies like Standard General, which is currently doing road work on Calgary's Glenmore Trail, a high-volume corridor with 85,000 vehicles a day, have other practices in place, besides frequent hazard assessments, to lower the risk of mishaps.

As well as roadwork, the company installs a lot of primary infrastructure, including sewers and water lines. Kondro says that bigger, improved equipment has boosted productivity so that excavation, below-surface work and then back fill is done in a tighter sequence. This means that the excavation is exposed for a shorter period of time with less chance that the surrounding soil becomes unstable because of rain or other factors. "Back fill crews are right behind, (with fill) that meets specific requirements to make sure the area (filled) is solid," says Kondro.

Sewer and water lines are typically three metres deep, but can be as much as five or six metres deep. Foundation and other underground structures for some commercial and industrial buildings can be at an even greater depth. Simon Schmid, manager for health, safety and environmental protection for Alberta with Ledcor Construction Ltd., says that weather-related change to conditions is not the only consideration when assessing stability.

"Even if the ground is bone dry and stays undisturbed you have to consider what kind of material it consists of," he says.

Measures used to reduce risk include shoring and trench boxes, which are often essential tools for ensuring safety. Sloping is another "“ "30 to 45 degrees depending on soil conditions, although 45 degrees is the best rule of thumb," says Schmid.

A recently added component in concrete pipe design is making loading and unloading pipe a safer, easier process. "A lot of the concrete pipe we use now has lifting attachments built into the pipe and anchor points," says Kondro.

Adding to the challenge in recent years, however, is a big increase in underground utility components. "Twenty years ago there were fewer lines. Now there's lots of fibre optic cable. Property has become so tight that it's more difficult to find space to work," says Kondro.

Also, although contractors obtain information from Alberta-1 Call and work with utilities, they can't rely on the data always precisely pinpointing the location of an underground line. Because of this, site workers should apply the precautionary principle when excavating, says Schmid. Also, he says, "In trenching or excavation, you should always have a spotter on the ground, as there are blind spots for operators. Operators shouldn't work alone but it happens all the time."

Unlike bigger contractors with full-time safety staff, smaller firms that spend time on safety training face a potential upfront cost in the form of production loss. The result, it appears, is that they are more tempted to gamble with safety.

Gary Wagar, the executive director of the Alberta Construction Safety Association (ACSA), points to both sticks and carrots to encourage safe work practices. "Supervisors and management are required by law to inform workers of the safe, appropriate practices, otherwise they can be fined," he says. Fines have been getting a lot steeper, lately, and are often in the $100,000 to $300,000 range, he says. "That can be enough to put a smaller contractor out of business."

On the other hand, companies whose personnel take ACSA safety courses and obtain a Certificate of Recognition (COR) or Small Employers Certificate of Recognition (SECOR) "can get a cut in premium rates as much as 20 per cent," says Wagar.


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