Highway to Alaska's North Slope fortified against flooding ahead of winter

DEADHORSE -- If another extreme spring flooding event strikes the northernmost stretch of the Dalton Highway, Alaska transportation crews will be ready, officials say.

"A number of factors (determine) whether there will be another flooding event next year," said Michael Lund, a construction manager at the Alaska Department of Transportation and Public Facilities who is overseeing upgrades to the highway. "Some of those factors are frankly unknown. But if it happens again, we will be much better prepared for it."

The Sagavanirktok River originates in the Brooks Range and runs north, paralleling the Dalton Highway, until it drains into the Beaufort Sea near Prudhoe Bay. Last winter, the river froze to the bottom. With the onset of spring, unusually high levels of water drained from the Brooks Range, overflowing the frozen waterway and flooding a wide stretch of tundra -- including the highway.

For almost a month, the road was impassable and oil operators at Prudhoe Bay were forced to improvise ways to move supplies such as drilling lubricants. Instead of tractor-trailers, the operators settled for less-efficient air transportation and convoys of rolligons, whose wide, low-pressure tires allow movement across the flat tundra without causing damage.

Since the Dalton was reopened in June, Lund's construction crews have elevated the highway where it was most affected by flooding, built new culverts to allow water to flow underneath it and stockpiled gravel at nearby sites. The project was suspended last week for the onset of winter. Transportation officials expect to complete it next year.

Using more than a million tons of gravel, workers raised the stretch of highway from Miles 397 to 405 by about 2 feet to a height of 7 to 10 feet above the surrounding tundra, according to the DOT.

As a precaution, the department spent an additional $1.1 million to excavate, process and stock 200,000 tons of gravel, Lund said. "One of the challenges this spring was the availability of material," he said.


But if that stockpile is not needed for an emergency, it will be used for summer repairs, he added.

Lund hopes regular DOT maintenance crews -- however handicapped they are by state budget cuts -- will be able to respond to most weather-related disruptions of the road that serves the Prudhoe Bay oil fields year round.

But in the event of more severe scenarios, additional heavy equipment has been set aside.

Many of the excavators, bulldozers, and trucking and hauling units used in the construction this summer are to be stationed nearby through the winter and can be mobilized for emergencies such as a flood, Lund said. Moving snow and gravel with the vehicles, crews would build channels to divert the water and barricades to protect the road.

And in coming years, transportation officials plan to continue elevating an 18-mile section of the Highway south of current construction efforts.

These upgrades to the Dalton Highway represent a prudent attempt to curb the impact of climate change on infrastructure, said Billy Connor, the director of the Alaska University Transportation Center.

"Evaluating whether (the flooding) will be repeated is high speculative," said the retired research engineer.

"(But) weather patterns are changing and we are trying to understand the risks."