At its January 8, 2018 meeting the Snoqualmie City Council took measures to address a landslide affecting one of its critical water sources, Canyon Springs, located at the base of a steep and unstable slope in unincorporated King County on the bank of the North Fork of the Snoqualmie River.
In mid November the 150 ft. by 90 ft. slide caused significant risk to a waterline that provides about 1500 acre-feet/year of drinking water to city water customers. The slide exposed and washed out an old wood stave pipeline that was originally installed in the 1950’s. Additionally, the 12-inch ductile iron pipeline that replaced that wood stave line in 1985 is now within six feet of the active scarp face of the slide. The city said that pipeline has been functioning normally since it was upgraded.
According to a city staff report if the unstable slope is not addressed soon, it may result in failure of the water line and extended disruption of service and supply operations.
During the meeting, the council passed a resolution declaring the emergency and then two contracts totaling $40,000 with Aspect Consulting and RH2 Engineering to evaluate slope stabilization and pipe alignment options, as any further raveling or movement could compromise support of the pipe or cause its failure. According to a council presentation, “failure is imminent within a couple of years.”
By declaring the emergency, the city council bypassed the legally required competitive bidding process for the project, which could have added weeks timeline. The staff report further stated, “Appropriate engineering designs must be promptly prepared, now, in order that repair work can be timely bid and construction commenced at the earliest possible date.”
The city addressed the threat to Canyon Springs in a recent press release saying “there is no need for alarm to the community,” adding that the slide poses no danger to private property, homes or residents in the area.
Per the release, “Snoqualmie has two water sources in addition to Canyon Springs: North Wellfield near Tokul Road and South Wellfield near downtown Snoqualmie. In event of a failure to the Canyon Springs line, those water sources will fulfill the Snoqualmie’s drinking water requirements, however, water conservation measures may be necessary.”
The City said it will update the public about repair progress.