Slide puts the spotlight on hillside challenges
The deadly mudslide last week in Washington State has brought into sharp relief the menacing power of nature.
But Mayor Sharon Gaetz said Chilliwack is no more at risk for landslides than any other B.C. communities with surrounding hillsides, such as North Vancouver or West Van.
If anything the recent slide incident in Washington State's Snohomish County has "strengthened our resolve" to do their very best with mitigation efforts, she said.
It's been a painful reminder of what can happen.
"It has been incredibly sad watching the aftermath of what happened near Arlington, Washington. Our hearts go out to the families at this time of terrible loss," Gaetz said.
It also puts the spotlight on some of the unique geotechnical challenges.
"From the City of Chilliwack's perspective, we need to do everything we can to mitigate the potential effects of something like that ever happening."
That was part of the thinking behind the evolution in recent years of the Hillside Development Standards Policy.
The city's original "guidelines" on hillside development from 2008 were updated and solidified into an official policy last year.
"We've learned an ounce of prevention is worth a pound of cure," said Gaetz. "Our policy now has teeth."
If they can mitigate risks by requiring the geo tech engineer to sign off of proposed development, for example, and confirm the extent of any logging above the area, it's a start.
"The policy clearly stipulates the responsibilities of the developer and engineers on this," she said. "It underlines the fact that we want to make sure those houses are safe."
There are many checks and balances in place now, but still no local government "can completely insulate you from Mother Nature," she said.
Whereas in the past the hillside assessment process was relatively quick, now it's a matter of paying very close attention to detail with a prescribed level of professional scrutiny.
"They have to engineer every specific lot that is being proposed. They sign off on the plans and take responsibility if anything goes wrong," Gaetz noted.
While there is always a chance of a landslide occurring on steep slopes, it is important to understand that the term landslide actually describes many types of downhill earth movements ranging from rock avalanches and debris flows in mountainous areas, to more slow moving earth slides, according to staff. Many factors can trigger landslides including: heavy rainfall or rapid snowmelt, erosion, poor construction practices, freezing and thawing, and shaking caused by an earthquake.
The value of geotechnical expertise, which is used to review sites and conditions to identify potential risks, is paramount in the process.
"We've been learning about development on hillsides and the risk that comes along with it. But when we're trying to protect farmland as Chilliwack has, there's not much other choice but to consider it."
Some of the older properties were not subject to the same scrutiny they have to employ with the development projects of today, said the mayor.
"We are now infilling on the valley floor, but if we go back 10 years or so, there has been significant development on the hillsides around Chilliwack."
Growth projections by city staff show there could be 1,200 additional homes in the Eastern Hillsides over the next 20 years.
About 85 per cent of new residential growth will be on the valley floor, in the Chilliwack Proper-Sardis-Vedder corridor through infill redevelopment and densification. It's an established trend they've seen over several years.
Only eight per cent of the residential growth will happen on the hillside areas with the remaining growth is distributed across the rural areas, according to OCP 2040 Growth Projections by Neighbourhood.