Fully fixing Fort Smith’s riverbank may be too costly, impractical
A slope stabilization study for Fort Smith’s Slave River bank – originally scheduled for completion in March 2019 – has finally been made public.
What’s happening to the riverbank has been a significant concern since a landslide in 1968 killed one resident of Fort Smith and swept away trees and homes.
The latest study, dated October 2019, follows other reports dating back to 1978 that have examined the bank’s stability.
While town councillors hoped the 2019 report would set out a plan to stabilize the bank and a corresponding budget, the consultant instead recommended the Town of Fort Smith develop a slope monitoring system and only remediate areas of the bank as required.
The report doesn’t include a budget, but the consultant encouraged the town to consider alternatives to regrading, a process of reworking the bank’s slope that the report says would come with a “significant” cost.
Moreover, the consultant concludes, the town might find acquiring an environmental work permit for regrading “challenging or impossible” given the environmental impact of clearing trees near the shoreline.
If regrading does go ahead, the consultant said the ideal, most stable slope would be six degrees. That would mean removing 16 million cubic metres of soil plus vegetation along private, municipal, and territorial land bordering most of the town.
“To give some sense of the magnitude of materials to be removed, think filling an NFL football stadium,” read a briefing note prepared for town councillors ahead of a meeting on Tuesday.
Senior administrative officer Cynthia White said a six-degree regrading of the bank’s slope would have extraordinary consequences.
Going ahead with that slope, White said, would “lose a significant amount of town, private, and other government infrastructure, including roadways and the arena, the St Isidore cemetery, part of the water treatment plants, [and part of] Queen Elizabeth Territorial Park.”
Previous studies suggest the slope of the bank is typically stable between five and 10 degrees. Right now, most of the lower and middle sections of the slope aren’t far off, at around six to 11 degrees in steepness. However, upper portions of the slope are typically much steeper, ranging from 27 to 38 degrees.
“Resloping to 10 degrees has the least impact on infrastructure and requires the least amount of soil to be removed,” the briefing note for councillors continued. But the consultant says 10 degrees “is unlikely to have the desired effect of significantly avoiding or reducing slumping and sliding.”
Referencing the report, the briefing note concluded “it is unlikely that a wholescale resloping of the riverbank within municipal boundaries is logistically and environmentally feasible.” That’s why the consultant recommends monitoring the bank and fixing priority areas instead.
More drone data on the way
The latest report has been in the works for years. In 2017, Fort Smith received $166,000 from a federal climate change adaptation fund to develop a plan to fix the riverbank’s slope.
Wood Environment and Infrastructure Solutions was awarded a contract to complete the work for $150,000 in December 2018. The company reviewed previously completed studies from 2004 onward, LiDAR (light detection and ranging) data from 2009, and related historical data.
Wood also identified areas for further study before any decisions are made. As part of this, the company is arranging for a contractor to visit Fort Smith in mid-September to fly a drone and collect updated LiDAR data, which will allow the consultant to assess movement of the slope over the past decade.
Once Wood has that data, the company says it will be able to create a monitoring and management plan and recommend strategies and equipment.
“I think this data and monitoring program will help us to engage the federal and territorial government in better managing degradation of the slope and, hopefully, take the burden off the Town of Fort Smith as the sole body of interest on remediating the slope,” White told councillors this week.
White noted the town is “well within” the contract’s budget to continue investigating and monitoring the situation.
“Having proper data and having a proper monitoring system is going to be central over the long term,” she said. “We don’t know … what the impact of climate change will be on that slope, and whether or not resloping now will be of benefit in 20 years due to climate change.”
‘Just keep at it’
Not all town councillors welcomed the report with enthusiasm.
“There’s nothing more disappointing than spending a lot of time and finding out that their recommendation is to just keep at it,” said Councillor Chris Westwell.
“I feel there are issues that come out of ‘remediate as necessary’ … the capacity to do so on short notice or demand is an issue,” he worried.
Councillor Jessica Cox expressed concern about slumping along the sandy riverbank in recent years – in June 2018 a landslide appeared to strike the ski hill, and in late November 2018 the Department of Lands warned of “large cracks“ showing up along a trail that subsequently slumped in May 2019.
In light of those events, Cox was unsure monitoring and remediating as necessary would be the best approach.
Deputy mayor Kevin Smith wants Wood to update its report with data showing how the high water levels and precipitation of the past two years have affected the slope.
And Mike Couvrette, another councillor, pointed out a significant amount of the land most in need of remediation is Commissioner’s land.
“I don’t see that it’s in our best interest, as a community, to be putting a bunch of resources into remediating land that the Commissioner has, at least in the past, shown no intent of ever transferring to the community,” Couvrette said.
“You look at our last few requests for land transfers and, my God, you talk about stonewalling, dragging your feet. Every other trick in the book to delay the land transfer process has been used.
“So I think until they’re willing to be a vested interested party in this process, the recommendation to deal with it as-is is something we’re going to have to seriously look at.”
In 2018, senior administrator at the time Keith Morrison told Cabin Radio the GNWT “has to play a role” in fixing the riverbank, given much of the affected land is under territorial control.
In 2019, a Department of Lands spokesperson said the territorial government’s responsibility extended only to inspecting, documenting, and reporting on the state of the riverbank.
“We leverage social media to keep residents informed when there are changes observed and will continue to do so in the interest of public safety,” the spokesperson said.