In the wake of an earthquake felt locally this month and the Great British Columbia ShakeOut emergency preparedness exercise last week, a Squamish resident is questioning what will happen in the event of an earthquake once Woodfibre LNG is up and running.
The magnitude 2.3 earthquake that rocked some Squamish residents awake at 2 a.m. Oct. 11 was along the same fault lines as two previous earthquakes since February 2015.
“The fault lines down through the Woodfibre site and across to Britannia indicate the energy transfer from the epicentre and explains why the quakes were felt in Squamish and Britannia,” said Star Morris, a citizen scientist in Squamish.
Morris said she is particularly concerned about the Henriette Lake Dam upstream on Woodfibre Creek. Based on a 2010 report, Henriette Lake Dam was deemed deficient to resist an earthquake “and could possibly be breached and initiate a debris flow,” according to Morris.
“The 10-inch gas pipeline is buried five feet under Woodfibre Creek and would be likely crushed should Henriette Dam fail,” Morris said, adding this failure may not affect the 24-inch natural gas pipeline to the liquefied natural gas facility, but the gas to the Sunshine Coast and Vancouver Island would be cut off with such a failure.
“With that dam sitting right now there is nothing major downstream, but when it is up and running will be the other issue.”
As part of the Environmental Assessment process, Woodfibre LNG laid out a number of its plans and precautions that will be undertaken in preparation for an earthquake including that the project will be designed for a one-in-2,475-year earthquake.
Further, related infrastructure, including bridges, will be designed for 200-year “instantaneous peak flows” on Mill and Woodfibre creeks.
With regard to the 1947-built Henriette Lake Dam in particular, Woodfibre spokesperson Jennifer Siddon told The Squamish Chief because the rules for dam safety in B.C. changed in February, engineering consultant Ausenco conducted a review of the dam and the company is still awaiting the 2016 Dam Safety Review.
“The preliminary finding of the review is that there are no serious issues of concern with the dam that would require immediate attention,” read an emailed statement from Woodfibre.
“Another preliminary finding is that the dam may not meet the new earthquake design criteria for being able to withstand a one-in-1,000-year earthquake.
While we await the final results of the review, we continue to remain in contact with the regulator and perform regular maintenance and inspections on the dam.”
In terms of public safety, Siddon said there is no immediate risk to the public because of the dam’s remote location. Were the worst to happen and a landslide occur above the dam, the debris flow would not reach the Woodfibre LNG site because of its location, she said.
Morris said she understands Woodfibre has plans in place, but she doesn’t have a high level of confidence that government regulators will ensure Woodfibre will follow through “before something happens.”
“From a number of issues with the provincial government throughout the province, I don’t have a lot of confidence,” she said.