ROADS/BRIDGES: AK’s sole North Slope access road in danger of severe flooding

The imminent spring thaw in the region is seen as comparable to conditions that closed the road last year

March 24, 2016

The only road leading to Alaska’s North Slope oil fields is at risk of severe flooding during the coming spring thaw. Climate experts believe the conditions will be similar to those that intermittently closed portions of the remote highway for more than two months in 2015.

State transportation crews are digging trenches near a vulnerable northern stretch of the 414-mile Dalton Highway to protect it from overflow from the Sagavanirktok River, generally referred to as the Sag River. Crews also constructed a 5-ft-high berm over a 3-mile stretch on the east side of the highway earlier this year, according to Alaska Department of Transportation spokeswoman Meadow Bailey.

The highway saw unprecedented flooding last year, prompting the intermittent closures. In response to the flooding, Gov. Bill Walker twice issued disaster declarations. Known as Haul Road, the mostly gravel Dalton Highway begins near Fairbanks and leads to Deadhorse, the oil industry town serving Prudhoe Bay.

The level and configuration of the ice surrounding the highway is similar to last year's conditions, and so is the current snowpack, Bailey said. Officials also are monitoring spring temperatures, which last year were unusually high in the area, hastening the rate of melting. Temperatures in the area are expected to be above normal in April and May, according to the National Weather Service hydrologist Ed Plumb.

Last summer, crews raised several miles of roadway as much as 8 ft, launching a three-year Dalton Highway reconstruction project that is projected to cost $114 million.

Transportation officials also are working with University of Alaska Fairbanks researchers determine what's behind the phenomenon. Among them is UAF Civil engineering professor Horacio Toniolo, who said two main factors were involved in last year's flooding—a significant ice accumulation and a very fast rate of melting. Researchers are now trying to determine all the various water sources that could be involved in the flooding at a level not seen before at any other time in the highway's history.

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