A sign warns off travelers on the road leading to the south gate of the Cold Lake Air Weapons Range, a military facility that is now home to the operations of five oil sands companies. Brian Harder for Al Jazeera America

The range overlaps with the Cold Lake deposits of Alberta’s oil sands. In the past two decades, every major multinational company has set up shop in this province, reaping trillions in revenues from the tarry, semisolid form of oil beneath. To date, much of the crude, known as bitumen, has been removed through surface mining, the process of digging oil from the ground that creates the giant moonscapes that have dominated media coverage of the oil sands. But here, on the Cold Lake Air Weapons Range, another means of extraction is used: thermal-steam injection.

Grandbois once worked on the oil sites as a technician, monitoring the flow of steam and tar from the vast network of pipes. But five years ago he quit over what he saw. The land, which he recalled from his childhood as “beautiful, wild and free,” had been transformed. “It was terrible. Roads all over the place, oil and gas facilities all over the place,” he said. “It’s ruining the land. I don’t want to be part of the destruction of the planet.”

COLD LAKE, Alberta — Behind the gates of the Cold Lake Air Weapons Range, guarded by military personnel, Brian Grandbois sometimes goes hunting for moose. As a member of the First Nations community that used these grounds for generations, he has rare access to the 1.6-million-acre site. In the 1950s, this land was closed to visitors when the Canadian government converted it into a bombing range. But today, the military is not the only tenant here. In recent decades, the eastern part of the range has become home to the operations of five major oil companies.

Editor's note: This is the third in a four-part series on Canada's oil boom. The first story explored the low-paid temporary foreign worker economy, while the second examined a new regulatory process that the country's aboriginal people say is failing them.

“We’ve seen a lot of recent incidents,” said Mike Hudema, a climate-and-energy advocate at Greenpeace. “It’s an example of how little government and industry knows about these technologies. We just don’t know enough to operate them safely.”

Oil companies tout in-situ technologies as less destructive than surface mining. The methods forgo the need for open-pit mines, smoke-spewing purification facilities and toxic dumping sites. By contrast, steam-injection sites look like clearings in the woods with a lattice of pipes sprouting from the ground. But environmentalists and other critics say the technologies raise their own set of concerns. To build steaming facilities and oil well pads, patches of forest need to be cleared. The roads, pipes and power lines that connect the facilities cut across rivers and lakes, wildlife habitats and migration routes — swaths of land much larger than those affected by surface mining. Steam technologies also produce significant amounts of natural gas; one in-situ method known as steam-assisted gravity drainage releases three times as much carbon dioxide as mining. And, in recent years, a pattern of leaks at steam-injection sites has raised serious questions about the technologies’ safety, particularly in light of a geological formation under much of Alberta that aggravates the risks.

These methods, also known as in-situ technologies, are seen as the future of oil-sands development. Approximately 80 percent of Alberta’s oil sands are too deep to be mined, and much of what can be removed via mining has already been extracted. By injecting steam into the ground and effectively liquefying the oil so it can be pumped back out, companies that employ the in-situ technologies are able to reach far deeper than surface mining. In 2013, for the first time, the number of barrels extracted in Alberta by steam injection surpassed those removed by mining.

Sand left over from surface mining lies on the shore of a lake near a facility run by the energy company Syncrude. The lake was once much larger. Syncrude is in the process of restoring the lake to its original state. Brian Harder for Al Jazeera America

In 2006, an explosion at a thermal project in the Athabasca region, farther north, owned by the French company Total left a surface crater covering more than 2 acres. Three years later, about 500 barrels of oil leaked to the surface at the Primrose Lake facility, an operation on the Cold Lake range run by the energy company Canadian Natural Resources Ltd., or CNRL. Not long after, bitumen emulsion (mainly droplets of bitumen) was discovered in an aquifer that provides water to nearby communities. In May 2013, the Primrose Lake facility again experienced leaks as 7,409 barrels of bitumen spilled onto 51 acres of land. However, it wasn’t until July that news of the spill became public. That’s when a government scientist turned whistleblower leaked documents and photographs to the Toronto Star that showed dead beavers and birds and land covered in oil. The leaks have yet to be plugged, because, as CNRL scientists say, they don’t know how to stop them completely.

According to Harvard geochemist Benjamin Cowie, the leaks appear to be caused in part by a geological weakness, an eroding ancient salt formation that is destabilizing the rock that holds the reservoirs of oil in place. The formation extends under virtually all of the area in Alberta being exploited for oil. Oil companies have accepted Cowie’s findings; recently, a consortium of 13 energy businesses created a working group to further study the issue. Last year, citing the geological weaknesses, the Alberta Energy Regulator, or AER, which oversees energy development in the province, issued a freeze on new steam-injection-technology projects in northern Alberta, near the town of Fort McMurray. The regulatory body is also investigating the leaks at the Primrose Lake facility.

But after briefly halting production at the Primrose site, the agency allowed the oil company to resume low-pressure steaming there last September. Three months later, benzene, a carcinogenic substance found in gasoline, was discovered to be leaking from another CNRL facility near the weapons range into an underground aquifer. The regulatory agency has also allowed in-situ extraction to continue at other Cold Lake sites.

Chris Severson-Baker, managing director of the Pembina Institute, an environmental think tank, said the leak at Primrose “shows there’s a fundamental flaw in the whole design of the project.” The AER should require more evidence that steaming projects aren’t built on fragile rock and that safety precautions are in place, he said. “The regulator should be on the ball, asking more questions. If they don’t have that confidence, then they shouldn’t approve.”

Ryan Bartlett, an AER spokesperson, wrote in an email that in-situ methods “undergo a rigorous application review,” and “operators must address the specific risks associated with the geology of the area and the technology they are using to recover bitumen.” The risk of leaks can be reduced if “proper mitigation measures,” such as steaming at lower pressures, are put in place, and his organization was satisfied, he wrote, that CNRL had taken such steps at the Primrose Lake facility.

Hudema, of Greenpeace, said the technologies shouldn’t be used at all. He points not only to safety concerns, but also to greenhouse-gas emissions. A recent study in Nature magazine suggested that most of the world’s fossil fuel reserves, including the vast majority of Alberta’s oil sands, must remain untapped if the world is to meet the climate change target set in Copenhagen in 2009, which limits global warming to an additional two degrees Celsius.