The Village of Cumberland wants additional geotechnical work done on the dam at Allen Lake because of some uncertainty around materials in one location.
The reservoir at Allen Lake is located roughly 3.5 kilometres south of Cumberland. The lake serves as one of the main reservoirs to provide drinking water for the community.
Rob Crisfield, manager of operations, updated council at the Sept. 9 meeting on geotechnical work that has happened so far and additional work needed.
The dam was constructed, along with some saddle dams as auxiliaries, in 1996 to expand the water storage capability of the lake. In 2017, there was a mandatory dam safety review, and staff requested a geotechnical assessment of the main dam. This work in 2018 included drilling and establishment of two piezometers, which measure liquid pressure in a system. Council had budgeted $21,915 for work in the 2018 budget.
“We started that work, and it’s kind of wound into this year,” Crisfield told council.
The process has raised questions about one location.
“We’ve discovered there’s a small zone of unsuitable material,” he said. “It’s nothing super-alarming, but we definitely need to pinpoint it.”
Crisfield later defined “unsuitable” material as material that would not typically be recommended for the construction of a dam. The plan now is to define the scope of where the material is.
The consultant will be required to do extra work to finish the project and produce a report, as required by law. As a result, staff is asking for an additional $8,000 from the water stabilization reserve to cover the costs.
“We’ve discovered something that we can’t just leave unattended,” Crisfield said. ‘This was not anticipated because it was a new dam.”
Coun. Jesse Ketler asked whether the work would mean unsuitable material would be replaced with suitable material.
Crisfield replied, “I don’t want to jump to conclusions. The initial discussions I’ve had with the qualified professionals is the next step’s really to define the scope of the area.”
The area may be small enough, he added, to require only monitoring over time.
“At this point, we’re just trying to move this forward,” he said.
Coun. Gwyn Sproule made a motion to approve the expense of the $8,000 for additional costs and that staff bring forward an amendment to the 2019-2023 financial plan bylaw. Council passed the motion.