Excavating and trench work can be like diving into murky water: no one knows exactly what lies below the surface and will never know without getting wet. But unlike swimmers, equipment operators and workers with a job to do cannot opt out of taking the plunge.
Call-before-you-dig services should be employed to locate gas, utility and electrical lines in a work-related digging area. But potential finds dredged up by what lies beneath the earth’s surface can go beyond that.
Last year, workers in Edmonton discovered dinosaur bones while digging a sewer tunnel, just about the same time that workers at Ground Zero were recovering the ruins of an 18th-century ship.
However, what gets unearthed is not always benign. In August, workers in Vancouver dug out two artillery shell casings, one rusted out, but the other still live with the potential to explode. Weeks later, a Manitoba man was tilling the land on his rural property when he came across a live hand grenade, again rusty but ready to go off.
“If you come across something unexpected, there are not many precautions you can take, unless you know the history of the area,” says Jim LaFontaine, health, safety and environmental manager for Toronto-based Dufferin Construction Company.
The onus is on the site owner to inform contractors of any hazards of which they are aware, LaFontaine says. Full disclosure about how the land has been used not only serves worker safety, he suggests, but business interests as well, since unexpected discoveries could result in project delays.
Peter Eastwood, a labour and employment lawyer at Borden Ladner Gervais in Vancouver, would likely concur. “If there is something that isn’t to be assumed, like an underground utility,” Eastwood says, owners “have a legal obligation to share that information with all those who are working on their property as a workplace.”
He notes “the main legal issues in any case where you’re doing any excavation work is whether or not the owner of the property and the employers working on the property were aware of any hazards. Did they exercise due diligence in considering whether there were any hazards and taking adequate safeguards for the protection of workers?”
Dufferin Construction has strict policies that require all work sites to obtain locates for underground services and utilities before digging, LaFontaine says.
There will be a record of where and how deep utility lines are buried. However, that may not be the case for other potentially hazardous objects that can be unearthed.
If something is “five, 10 feet [three metres] below grade, there’s no technology I’m aware of that can sweep the ground and pick up anything,” LaFontaine says.
He recommends completing background checks, which may include a Phase I Environmental Site Assessment. As part of that, engineers carry out checks for what could be dangerous, based on the history of the site, previous operations and materials that may have been present.
Appropriate checks could show, for example, that a site was previously a petrochemical area where underground tanks may still be present, LaFontaine says. If that is the case, “you could take some precautions, such as probing.”
Failing to check may mean not knowing if it “was a former munitions site or if it was used as a bombing range,” he cautions. “We’re not Superman. We don’t have X-ray vision.”
That may have come in handy at Spring Valley, a 1,600-home community in Washington, D.C., complete with a university and several embassies. The site had previously been used for testing chemical agents, equipment and munitions during the First World War, notes a project summary from the U.S. Army Corps of Engineers, released this summer.
A probe in the late 1990s found burial pits with almost 300 ordnance-related items, 14 of those containing a chemical warfare agent. The Army Corps of Engineers is progressing with plans to resume clean-up activities in 2012.
John Agioritis is a lawyer for MacPherson Leslie & Tyerman LLP in Saskatoon who specializes in occupational health and safety issues. “Certainly, the idea of ‘buyer beware’ would apply,” Agioritis says of those contemplating purchasing property. It is up to the buyer “to do the diligence to ensure that what you’re buying is what you want,” he adds.
Under Saskatchewan’s Occupational Health and Safety Act, it is an employer’s duty to ensure the work environment is safe, Agioritis says. The description of the duty is broad, but if an employer knows the site where employees are working could be hazardous, precautions must be taken.
In Ontario, the OH&S Act states that employers must ensure that all gas, electrical and other services are located and marked before beginning an excavation.
British Columbia’s rules “require that, before excavating or drilling with any power tools or equipment, the location of all utility power services in the area are accurately determined and any danger to workers from those utilities must be controlled,” says Don Schouten, construction manager for industry and labour services at WorkSafeBC in Richmond, British Columbia.
Although digging up an unexpected danger is relatively rare, that does not mean employers are absolved of the responsibility to ensure protections are in place.
“Coming across an unexploded shell is certainly unusual,” Schouten points out. “But employers should make their employees aware that there’s always the potential for there to be something in the ground when they’re digging,” he adds.
“If, for whatever reason, an employer was aware that they were excavating an area where there used to be live artillery shells or underground mines, it would be safe to assume that proper due diligence would involve taking at least a few steps to make sure that you’re not going to be endangering any workers by the work you’re doing,” Eastwood advises.
Employers are also required to properly train their workers, Schouten emphasizes, “not just tell them, ‘Go dig that trench there.’ They have to understand that before they stick any shovel in the ground, certain steps need to be taken to try to locate anything that is possible.”
LaFontaine says that Dufferin Construction has done work on land previously used for fire training. Soil testing needed to be done, conditions monitored and workers equipped with personal protective equipment, he says.
“It’s in a general ventilated area, but once you open it up, it can be quite hazardous as far as toxic fumes or volatile organics and hydrocarbons in the ground,” says LaFontaine.
“Other than underground utilities and the usual things you’re concerned with, it’s really going to be primarily based on whether or not the owner or employer could have reasonably anticipated that you have any other types of hazards under the ground,” Eastwood explains.
“If someone was injured as a result of some excavation or some dig,” he advises, “you always have an obligation to do an investigation and look into the causes and contributing factors of the incident.”
Once every four years or so, a crew at Dufferin Construction will unearth something unexpected that brings work to a full stop and requires calling in the authorities or experts to handle the situation, LaFontaine says. Most commonly the find is bones, usually from a dead animal, he notes, but not always.
Once, a work crew in Toronto excavated a cylinder of chlorine gas and a hazardous materials team had to be called in to deal with disposal, LaFontaine says.
“It was probably around the World War II time. How it got there we don’t know.” Dufferin Construction had to use a vacuum truck to blast away and suck up the soil, LaFontaine adds.
“It was slow; it’s like dental work at that point,” he reports. “But it’s the only way we could go and maintain the workers’ and public’s safety.”
Greg Burchell is editorial assistant of OHS Canada