Village council at the time had decided not to follow recommendations of experts
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The report recommended the village get an expert to estimate debris flows on several creeks and run risk scenarios using that new information, and also have an expert estimate the frequency and magnitude of open-slope landslides affecting Lions Bay using computer modelling.
Ross Blackwell, Lions Bay’s chief administrative officer, said he has not had time to review the report that came to his predecessor and does not know what was done as a result of the report.
He said an examination of the report will take place later.
“Once we’ve taken care of all of these pressing priorities, there’s the ability to backcast and assess what worked well, and how do we plan for the future,” said Blackwell.
Jake Klas, who has lived in Lions Bay for 21 years, said the weekend slide was a “rude awakening” to the potential threat to the area.
Klas, who lives on the south end of Brunswick Beach Road, said the slide sounded like an earthquake, sending rocks and trees “flying” down to the highway in a matter of seconds.
He said he scrambled up Crystal Falls Road to get a closer look at what happened but was forced to stop at the bridge that crosses Magnesia Creek and connects with Glendale Avenue. Video he shot showed trees toppled all over the bridge.
“I’ve never considered this an immediate danger” when out hiking in the area, he said. “But now it’s something I’ll always be thinking about.”
The Enns had lived at 6 Glendale Ave. for about 30 years.
Family have said they carried out a number of renovations, including strategic tree removal to improve their views of the water far below, and built a veranda.
The slide began in an area around Battani Creek at around 10:30 a.m. on Saturday.
The 2018 consultant’s report had specifically recommended the Village of Lions Bay have an expert estimate the “frequency-magnitude” model for debris flows on Magnesia, Alberta and Harvey creeks.
But the suggested hazard target areas the report recommended also included alluvial fans, ravines and small creeks, which would include Battani Creek.
The report also noted the risk of debris flows on the upper slopes of Lions Bay.
It said that “above Highway 99 there are several lots below Crystal Falls that border natural stream banks with relief of 2-4 metres above the channel bed.”
The lots “could be vulnerable to debris floods … (caused by) rare large catchment overtopping events or from ravine side wall failures. Any debris that overtops the bank could then be directed down the surface onto the highway and down the Brunswick Beach access, to Brunswick Beach Road.”
Fred Bain, who was a Lions Bay councillor when it was decided not to implement development permit areas, said he did not know what has happened at council in the past two years.
At the time, council had instructed staff to bring back new amendments to the official community plan that would meet municipal legal obligations.
But Bain noted there is no beating the natural surroundings of community, which is on a steep hillside with streams and creeks.
“Without (higher-level) government support, I think there’s no way the tax base could afford to spend anything, or not anything, but not a lot on it,” said Bain.
In response to a Postmedia question, B.C. Ministry of Transportation officials said the province has not previously received any request for assistance or mitigation measures from the Village of Lions Bay for the area of this weekend’s debris flow.
Brent Ward, a Simon Fraser University earth sciences professor, said the high landslide and debris-flow risk is well known along the Sea to Sky Highway corridor.
Before significant hazard upgrades — including hundreds of millions in upgrades to the highway for the 2010 Winter Olympics — it was known as the highway of death, said Ward, the co-director of the centre for natural hazards research at SFU.
“The issue is that many of these communities along there, like Lions Bay and others, are built on what we call fan deltas. Those are formed because of the sediment coming out of those watersheds that include debris flows,” said Ward.
The most common hazard reduction method is to build debris flow basins that are meant to capture soil, rocks, and organic material and prevent downstream damage.
Ward noted there is one below the highway along Lions Bay.
There are things that property owners can do as well, including building a berm to deflect water and debris flows, but it is better to build away from creeks, he said.
The 2018 report had called on the Village of Lions Bay to adopt a landslide safety policy consistent with the District of North Vancouver.
Th district’s policy calls for reducing slope hazards and landslide risk to people and property by carefully managing development and construction practices on or near steep slopes, avoiding alteration of steep slopes that may cause instability of the land or adjacent areas.
It also calls for utilizing professional design of drainage structures and mitigation works with supervision during construction and post-construction certification, and encouraging continuing maintenance and monitoring of steep slopes.
With Postmedia files