Heavy rain across western Washington in February saw multiple landslides in the Snoqualmie Valley, including one on the shoulder of SR 18 – about 1.5 miles west of the Tiger Summit Trailhead.
To repair damage from this slide, at 8PM Friday, March 6th, WSDOT will close westbound SR 18 from Tiger Mountain Summit to Issaquah-Hobart Road until noon Tuesday, March 10th.
During the multiple day closure, travelers will detour via westbound I-90, I-405 and SR 167 or I-5.
According to WSDOT, the February 6th slide washed away soil under a wide spot of the westbound shoulder between I-90 and Issaquah-Hobart Road. Part of the pavement collapsed, but damage has not reach the shoulder yet. Soil erosion under the shoulder left a guardrail hanging and pieces of asphalt turnout collapsed.
To prevent any further damage, WSDOT will close the westbound lane so crews have enough space to safely dig out saturated soil from under the damaged turnout. When they reach solid ground – which is expected about 10 feet down – crews will place rock to fill and support the area, then repave it.