Enbridge (TSX:ENB) Inc. chief geotechnical engineer, Drummond Cavers, told the hearing that risk can never be reduced to zero, but mitigating the possibility of a resulting spill is the whole focus of the design of the pipeline.
"That's why we get the seismic values, that's why we look at the geohazards and consider the geohazards along the pipeline relative to the different mechanisms of geohazards, so that we don't have a catastrophic failure. That's exactly what we're designing for, and mitigating," Cavers said under questioning from First Nation's lawyer Jesse McCormick.
"So I understand... that such shaking could result in damage to the pipeline, including the possibility of catastrophic failure. Is that correct?" McCormick asked again.
"No, because we are mitigating it so that that doesn't occur," Cavers repeated.
"So do I understand your evidence to be Mr. Cavers that there is a zero per cent chance of any earthquake of a magnitude lesser than 7.5 to have any impact on the pipeline that would result in a catastrophic failure?" McCormick asked in response.
"No, we've stated before I think quite clearly that we can never get the probability of a hazard down to zero," Cavers said.
"But we are endeavouring to get the probability of a hazard that causes a loss of containment consequence down below ... one per 100,000 years for an individual event along the pipeline," he testified. "We can never get to zero, just as the probability no matter how careful a driver you are, that when you're driving back to the hotel tonight that you will not get in an accident. But our probabilities are probably much, much lower than those probabilities."
Probabilities of hazard, geomorphology, seismic risk calculations, horizontal directional drilling, the final hearings are not comprised of thrilling stuff for the average Canadian.
The hours of testimony before the three members of the joint review panel are looking at the most minute details among more than 20,000 pages of reports, planning and assessment conducted over more than a decade.
The stakes are high.
On one side, Enbridge has spent more than $300 million already on the $6-billion twin pipelines that would carry diluted bitumen from the Alberta oilsands to a tanker port planned for Kitimat, B.C. The second pipeline would carry condensate from natural gas from Kitimat back to Bruderheim, Alta.
The company says the project will boost Canada's GDP by $270 billion over 30 years, and would generate total revenues in direct and indirect benefits to the federal and provincial governments of $81 billion over 30 years. Of that, B.C. would receive about $6 billion, while Ottawa would receive about $36 billion and Alberta $32 billion.
On the other side, dozens of First Nations, conservation groups and individuals fear irreparable harm will result from a catastrophic oil spill, either from the pipeline on land as it traverses the pristine wilderness of northern B.C., or at sea, from hundreds of tankers that will navigate Douglas Channel to deliver the oil to the shores of China.
The stakes are so high that even agreeing on how to measure spill potential can be a bone of contention.
"In the event of a full-bore rupture, the more oil in the pipeline and the longer the time between detection and shut down, the greater the spill volume. Is that correct?" asked McCormick on Friday.
"Well, release volume is determined on the basis of the topographic profile of the pipeline, and ultimately on the locations of the remotely operable valve, the isolation points," Ray Doering, manager of engineering for the Northern Gateway project, responded.
It depends on the flow rate of the pipeline, the time it takes to close 132 valves along the line, he added.
"Once you close a valve, there is what we call a static drain-down component, and that is the maximum amount that can come out of a pipeline based on the topographic profile. So here, generally, the topography is helpful in limiting the amount of oil that can come out because there are natural constraints."
The process so far has elicited rare agreement between the B.C. government, conservationists and First Nations — none have been satisfied with the inexact answers they have heard from the company experts.
Janet Holder, executive vice-president of western access for Enbridge, defended the process.
"I think we have been giving the answers that British Columbians want to hear," Holder said outside the hearings.
Enbridge has opened an office in Prince George, and will have a greater presence in communities along the proposed route "to help them understand what this project is about."
"We've got time and we have plans. We're not walking away," she said.