Monday, February 1, 2021

Plans to reopen SR 112 in Clallam County moving forward

Update: Feb. 18, 2021
The soil beneath milepost 36.9 continues to shift. The roadway at this site has settled more than 13 feet. Environmental services crews will be on site next week to evaluate potential effects of construction on area species. Results from the environmental review will inform our next steps on this repair. We will continue to update this blog as we know more.
By Tina Werner

If you look up the definition of "wet," it reads: "Moistened, soaked or covered with water." It's the quintessential definition of a Pacific Northwest winter, and we aren't just talking about puddle jumping. This infamous winter weather has done a number on State Route 112 in Clallam County, resulting in more than a month-long closure due to slides.

Our recent challenges on SR 112 began on the first day of winter, Dec. 21, 2020. In one day, high temperatures, heavy rains, snow, and seasonal tides, resulted in our crews closing a section of the highway near the Pysht River. When crews inspected the roadway for potential reopening, they found roadway settlement in three separate locations.

Since the initial closure coupled with increasing rains, five total slide sites have been discovered. Our engineering geologists surveyed the locations using lidar imagery and collected pavement samples to make recommendations for reopening the highway.

As we wrap up January, here's where we are at:
  • Eight miles of SR 112 in Clallam County remain closed from mileposts 31-39
  • Five slide sites need repairs
  • A signed detour remains in place using SR 113 and US 101
  • Temporary repairs require an emergency contract
Five different areas of SR 112 saw mudslides that have kept the highway closed for more than a month.

We approach disaster repairs like these on a case-by-case basis. Some emergency repairs involve extensive debris removal and roadway cleanup, while others need significant highway engineering and hydraulic considerations before construction can even begin.
While SR 112 is closed, a signed detour is in place using SR 113 and US 101.

History of slide activity
SR 112, located on the Olympic Peninsula alongside the Salish Sea, sits on an active slide zone.  Our engineering geologists have documented significant slide activity every 10-20 years beginning in 1954 after the highway was reappropriated from Clallam County to WSDOT in the 1930s. The last major slide event was in 2009. The topographical and geological challenges along SR 112 require a calculated approach to address ongoing drainage, stability, and debris concerns.
Engineering geologists design unique solutions for each slide based on drainage concerns, debris and roadway settlement.

Getting SR 112 reopened
While all five slides created significant damage to the highway, the most serious and challenging repair is the fifth slide site at milepost 36.9. Portions of the roadway have dropped almost 13 feet and continue to move.
A look at one of the slides on SR 112 at milepost 36.9 where the roadway dropped almost 13 feet.

Our priority is getting the highway open as quickly and safely as possible but it's no easy task. It will take coordination, planning, and lots of elbow grease to get the job done. We're reviewing design solutions that will enable us to reopen SR 112. An example of the work ahead includes installing new culverts and repairing adjacent slopes along the highway. Some sections of SR 112 may reopen as temporary gravel surfaces. An emergency contract will be needed to repair the slide sites, with the intention of reopening the highway as soon as possible. This work will start as soon as the slides are stable enough for crews to safely begin work.

Once we know more, we will share updates on this blog, social media and via email.

We know many are anxious for SR 112 to reopen, and so are we. Recent storm damage to US 101 near Lake Crescent, our detour route, has created a challenge we are simultaneously addressing. We want you to know crews are working nonstop on both locations.

Hopefully, the storm clouds will ease in the coming weeks. Thank you for your continued patience.

1 comment:

Unknown said...

Thank you for the update, it was very informative, especially liked the explanation of variables to be considered.

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