There are 47 locations in Moose Jaw where the land is slumping to some degree, with four geohazards considered a high priority to monitor because of the severity of the erosion.
To ensure these sites are monitored properly, city council voted unanimously during its July 11 regular meeting to award the 2022-23 slope monitoring program contract to AECOM Canada Ltd. Moreover, it voted to give the contractor $260,000 for the program, with funding to come from the 2023 capital budget.
The capital budget for this initiative in 2022 and 2023 is $695,000, while the five-year budget to address slumping is over $2 million.
Background
In 2021, city hall retained Vertex Professional Services Inc. to provide a slope monitoring program report. The contractor provided a report in September, which identified and prioritized locations and proposed scope of work for continued monitoring, a council report explained.
The report’s recommendations have various risk control activities based on each location’s severity level and activity. The program’s monitoring schedule will occur over two years to reflect these recommendations.
No actual mitigation work will start until likely 2024 or 2025. City administration will bring a proposal to a future budget meeting when it is ready to address slumping areas.
The report shows there is one geohazard with a “very low” status, 23 locations with “low” status, 12 geohazards with a “medium” status, 11 locations with “high” status and zero geohazards with “very high” status.
High-concern areas
The four geohazards considered a high priority include an area south of Grandview Street West; an area within the 800 block of Skipton Road; the west-facing roadway embankment along Wellesley Street East; and an area west of Aldersgate Street and Seventh Avenue Southeast.
At Grandview, the area is located on a historical landslide slump and requires a detailed geotechnical investigation, the Vertex report said.
At Skipton Road, progressive toe erosion has caused a slope failure that has undermined the south property limits of two properties.
At Wellesley Street, there is a slope failure due to toe erosion encroaching on the west-facing roadway embankment along that street. Progressive erosion and slumping have caused a slope failure that is undermining the guardrails along the southbound lane, the report continued.
At Aldersgate and Seventh, a slope failure has occurred near the toe of the slope about 20 metres up. The slope failure has formed “a graben feature,” while a tension crack about 77 metres long has developed upslope from the head scarp.
The continued slope movement and erosion could undermine the integrity of an overhead power line upslope, while the nearest wooden utility pole is about 20 metres from the tension crack, the report said.
Council discussion
Coun. Doug Blanc was concerned that some slumping zones affected other agencies, such as SaskEnergy, the rail companies, or the Ministry of Highways. He wondered if those groups would help pay for mitigation work.
Once city administration understands the risks at each location, it will develop mitigation strategies, said Bevan Harlton, director of engineering services. Since it hasn’t developed strategies yet, he couldn’t answer whether those groups would be asked for support, but that is on the radar.
“I agree. We have to look at it now and see where the problems are,” said Blanc. “And when it comes time to put shovels in the ground, I believe they should be contacted.”
While AECOM is contracted to communicate to homeowners about this project, Coun. Crystal Froese was concerned that the agreement lacked an educational piece where the contractor would inform affected homeowners about mitigation efforts and preventing further erosion.
“… I see that if the company can’t take that on, maybe there is something we can do with the Water Security Agency or another agency that have information developed around that (mitigation efforts),” she said, adding this is especially important if area residents plan to sell their homes.
City manager Jim Puffalt replied that city hall would conduct an information campaign to the affected properties.
The next regular council meeting is Monday, July 25.
