WA: Nile Valley Landslide Project

2010 Top 10 Nominee
Innovative Management – Small Project
Nile Valley Landslide Project
West of Yakima, WA

“We are honored by the recognition that the response to the landslide was truly remarkable. This award is shared by the many local agencies that collaborated with WSDOT to restore highway access quickly and safely to the community. The SR 410 Landslide response required innovation, leadership, cooperation, determination, communication, and a dedicated team. We were able to build a detour route around the landslide and construct a new river channel before winter arrived and closed the only other highway access to the community.”

Don Whitehouse
Washington State Transportation South Central Region Administrator

On Oct. 11, 2009, a massive landslide destroyed a half-mile of State Route 410, west of Yakima, Washington, blocking and uplifting the adjacent Naches River, and flooding the parallel Nile Loop county road. Fortunately, no one was injured by the movement of millions of cubic yards of rock and soil, but life will be forever changed for the estimated 600 residences and businesses west of the slide, as well as travelers on SR 410.

SR 410 connects central Washington to the busy world of western Washington, via the 5,430- foot Chinook Pass, 38 miles west of the slide. Due to heavy winter snows and high avalanche danger, WSDOT closes Chinook Pass every winter, typically by late November. The pass remains closed until Memorial Day, effectively leaving the only access from SR 410 to employment, schools, and retail to the east.

Immediately after the landslide, the diverted Naches River flooded residences and the Nile Loop Road, cutting off the only remaining easterly access. WSDOT used innovative management in collaboration with Yakima County, which has jurisdiction over the river, to acquire needed properties, re-channel the river away from the landslide toe, monitor for additional landslide movement, and design and construct a 4,000-foot detour road that would withstand projected winter flooding. The state needed to ensure winter access for the residences and businesses that would soon to be shut off from the west. Six days after the landslide, Governor Christine Gregoire visited the site, and committed to opening the detour route by Thanksgiving, a 45-day rush timeline.

WSDOT and their emergency contractor worked 14 hours a day, seven days a week to construct a new river channel and detour, while their environmental experts coordinated with resource agencies to ensure we mitigated and/or minimized long term impacts. On November 24, the day before the promised target, WSDOT opened the detour to traffic.

WA: Nile Valley Landslide Project

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