SR 410 Dry Creek Vicinity - Emergency Slide Repair - Complete October 2023

Project overview

Contractor crews working for WSDOT installed a 10-foot, corrugated metal pipe under State Route 410 to allow Dry Creek to pass beneath the roadway along its new channel. This is the second part of emergency repairs following a debris flow in fall 2022, which permanently changed the course of Dry Creek and overwhelmed a 24-inch culvert.

Work to increase stream capacity at Dry Creek began in February 2023, when three overflow culverts were installed to augment the existing 24-inch culvert approximately two miles north of the road to Crystal Mountain Ski Resort (milepost 55). This temporary fix reduced the risk of flooding damage to the roadway until the larger culvert be installed in fall 2023.

Timeline

January 2023 - Fall 2023

Project status

Completed

Funding

$1.9 million

What to expect

Major construction is complete and no traffic control is expected at this time.

Completed 10-foot culvert beneath State Route 410 near Crystal Mountain Ski Resort.

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A 10-foot, corrugated metal pipe was installed beneath State Route 410 to allow Dry Creek to pass beneath the roadway along its new channel following a debris flow in November 2022.

History and background

In early November 2022, the area around Dry Creek experienced several inches of rain over several days resulting in a Nov. 5 debris flow that covered State Route 410. The roadway was blocked for several hours with mud, rocks, trees, and boulders several feet deep and the road's west embankment was damaged.

Crews were able to clear the roadway, however, Dry Creek has shifted to a new channel that flows into an undersized 24-inch culvert, rather than the larger four-foot concrete culvert it previously flowed through. The previous channel is permanently blocked by debris located outside WSDOT’s right of way on U.S. National Forest land. As winter progresses into spring, snowmelt and rain will increase runoff, which then increases the risk of roadway damage or washout.

WSDOT determined that a two-stage emergency project was needed, first to minimize the flood risk from Dry Creek, and the second to install a longer-term solution that will result in a full roadway closure.

To maintain access to recreational and emergency access to Crystal Mountain Ski Resort and other businesses and residences, we installed temporary culverts beneath SR 410, which will allow us to maintain access during construction. Then in fall 2023, we installed a 10-foot culvert under SR 410.

Milestone

November 2022

Debris flow blocks SR 410 and changes path of Dry Creek to a smaller culvert.

February 2023

Temporary culverts installed to divert runoff from overwhelming the undersized culvert Dry Creek is currently using.

September 2023

Construction begins to replace smaller culvert with a larger, more permanent 10-foot culvert.

October 2023

Construction completed.

Location of Dry Creek's old and new paths following a November 2022 debris flow along State Route 410 near Mount Rainer National Park.

Water and debris flow across State Route 410 after heavy early November rains.

Heavy rains in early November caused a debris flow along Dry Creek, which plugged the creek's channel and sent water, mud and rocks over the highway.

Water pours over State Route 410 embankment, damaging the embankment. Undersized culvert is shown.

When an early November debris flow caused Dry Creek to change channels, it overwhelmed a 24-inch culvert under State Route 410. The debris and water plugged the undersized culvert, causing debris and water to spill across the highway and scour the westside embankment.

Three metal, round overflow culvert are burried beneath the SR 410 roadway. In the foreground, ice is shown above the existing 24-inch culvert.

Crews installed three overflow culverts beneath SR 410 in February 2023. The culverts will help the existing 24-inch culvert handle spring runoff until a larger, more permanent culvert can be installed this fall.

SR 410 Dry Creek Vicinity - Emergency Slide Repair - Complete October 2023

Project overview

What to expect

History and background

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