Enbridge is doing extensive geotechnical work to avoid the risk of landslides along the proposed route of the Northern Gateway pipelines, says director of engineering Raymond Doering.
“We understand, totally, the features in the area that have resulted in slides that might have affected other pipelines or highways or railways,” Doering said. “What we’ve done is work to identify a route that avoids those hazards.”
Doering said the proposed route runs south of existing pipelines, such as the Pacific Natural Gas pipeline that crosses the Telkwa Pass.
Other new pipeline proposals, like the Pacific Trails Pipeline, are following that lead.
Over the last 30 years, landslides cut the more northern PNG pipeline three times.
But geotechnical knowledge has come a long way since then, Doering said.
For example, he said, surveyors now realize why it’s important to know that some 10,000 years ago, the Kitimat Valley was the bottom of the ocean. That land rebounded as Ice Age glaciers melted away, leaving pockets of glacial marine clay that is unstable.
“That’s a very well understood condition now,” Doering said. “But it wasn’t well understood when the original PNG pipeline was routed down to Kitimat over 40 years ago.”
Enbridge is doing ongoing fieldwork—digging bore holes, doing remote-sensing flyovers and aerial photography—to assess such risks, he said. Enbridge began its geotechnical surveys in 2005. Last year, the company submitted a long report detailing its geotechnical surveys for the Joint Review Panel that is assessing the project.
“We don’t just look on the corridor,” Doering explained. “We look as far to either side of the corridor as necessarily, and sometimes it’s many kilometres.”
Wherever possible, Doering said the proposed route avoids geohazards.
Where hazards are unavoidable, his team will engineer ways to mitigate risk.
For example, Enbridge plans to dig two tunnels, one 6.5 km and one 6.6 km long, to route its twin pipelines under the Coast Mountains.
“It’s a huge investment,” he said. “But it’s a huge investment in the safety of the workers and for the long-term operation in the pipeline.”
Doering was responding to concerns raised in a recent report by James Schwab, a retired geomorphologist, that was published by the Bulkley Valley Research Centre.
The Schwab report concluded that landslides will eventually cut any pipeline routed through west central B.C.
But in his study, Doering said that Schwab made specific reference to the Enbridge proposal or any of the geotechnical they have filed with the panel.
“We are already generating a response, section by section, which will be on the public record,” he said. “We’re prepared to describe the length we’ve gone to mitigate and avoid those hazards.”
Doering said he expects the Schwab report will be included among the 215 other intervenors who have submitted information requests to the Joint Review Panel.
“They are important questions—there’s no doubt,” he said. “People want to make sure you are doing the work. And we are being as thorough as we can be.”
A full record of the Enbridge proposal is available on the Joint Review Panel website at gatewaypanel.review-examen.gc.ca.