City proceeds with plans for landslide stabilization around Canyon Springs water source

After a recent landslide put one of Snoqualmie’s water sources in danger, the Snoqualmie City Council took action to protect the spring from future risk. At their Feb. 16 meeting, the council approved a consulting agreement with Aspect Consulting, to repair and reinforce the slope above Canyon Springs.

The spring box water collection facility located along the North Fork of the Snoqualmie River, Canyon Springs, is one of the city’s primary water sources. Canyon Springs provides more than 1,5000 acre-feet of water per year. When crews went to the site for maintenance in December, they found evidence that a landslide had occurred on the slope, which put the pipeline that carried the water at risk. If the ground were to move further, the pipe could fail completely.

Jeff Hamlin, city engineer, updated the council Feb. 16, before they voted to approve the agreement. He said the city already had Aspect Consulting, a geotechnical engineering group, under contract for another project and said they have already looked at the site since the city’s discovery. Aspect has done a preliminary assessment of the slide and developed a recommendation to use anchored mesh supports for stabilizing the slope.

Aspect will inspect and analyze the site as well as plan and design the proposed anchored mesh slope stabilization. Once the design is complete the company will support the city in putting out a request for bids to find a contractor to build and implement the stabilization. They will also oversee the construction process full time. The total project budget for Aspect is $92,504.

Hamlin said the recommended stabilization method could provide stability for up to 50 years and is less environmentally disruptive than other methods. If approved, he said, the next phase would be design, plus further analysis to get plans and specs in place for the project. He also added that the current system has been in place for 34 years.

“Once we initiate the design phase there are several things that are going to be happening,” he said. “One of the them is to go up and take samples, we need to get some lab work done, classify the soil a little bit better where we are going to be applying this netting technique.”

Councilmember Sean Sundwall asked Hamlin about the construction cost and timeline. The cost of actual construction is not included in Aspect’s agreement and will be determined later, Hamlin said. He is hoping that the entire project will be completed by October with an estimated eight weeks of total construction time.

“If we can get to it by August, we can get through it by October,” he said.

Once further design and evaluation is done, the city could also choose to make other improvements to the water collection location including security in the form of fences or gates, and roadway improvements to help get equipment into the area.

Following the council’s unanimous approval of the agreement, Aspect Consulting began work on the project.