Water behind 'damalanche' slowly drains; more of highway cleared

Anchorage Daily NewsJanuary 29, 2014 

"Damalanche."

The monster snow slide and lake covering the Richardson Highway at Keystone Canyon outside Valdez now has a name.

The city coined a word to describe the extraordinary combination of avalanche and flooding that's closed the only road in and out of town.

The Richardson Highway will remain closed in the near future by a monster pile of snow that plugged the Lowe River and turned it into a lake. The water was slowly receding, but it still submerged about 1,500 feet of highway as of Wednesday.

While road access to Valdez remains blocked, a northern section of the highway reopened Wednesday afternoon.

The Alaska Department of Transportation and Public Facilities opened the highway from Mile 42 to Mile 18. Crews cleared a large avalanche at Mile 19 and checked the surrounding Chugach Mountain slopes to make sure the risk of them sliding again was low, officials said.

The avalanche at Mile 19 had trapped residents of the Heidenview subdivision, about nine households including a couple of families, according to Kate Dugan, a spokeswoman for Alyeska Pipeline Service Co. who lives in the subdivision that's usually only about a 25-minute drive into Valdez.

Dugan said everybody managed fine. An Alyeska helicopter dropped off food -- milk, eggs, cheese, fruit and vegetables -- on Monday.

"It's really quiet," she said Wednesday morning. "This year because it's been so warm we can hear waterfalls. For me, that's a very powerful mental marker for spring, or early summer."

BIRTH OF A DAMALANCHE

One avalanche down. One damalanche to go.

The catchy label came from Valdez city officials and took off among locals, deputy city clerk Holly Wolgamott said.

More than 11 inches of rain falling on deep mountain snows over a two-week period triggered two big avalanches that blocked the road at Mile 39 near Thompson Pass and at Mile 16 in Keystone Canyon on Friday.

Then state Department of Transportation crews dropped avalanche-triggering explosives on the slopes at Mile 16, an area known tellingly as Snowslide Gulch. That sent an even bigger avalanche thundering down on top of the first one.

The resulting monster mountain of snow -- first estimated at 100 feet tall and 1,000 to 1,500 feet long -- dammed the Lowe River. It created a roughly 500 million-gallon lake that stretched back a half mile and basically filled the canyon.

From the air on Wednesday, the lake still looked big enough to float a ferry. It was dotted with sheets of ice and tree branches wrenched from the mountainside.

The Richardson Highway was a thin string of asphalt suddenly consumed by an ocean of snow, striped soot gray or the color of coffee grounds.

The debris field at Mile 16, which officials have estimated to be as much as 100 feet high, looked like it could have swallowed Valdez's Safeway store, high school and a handful of houses to boot. It made an empty bulldozer parked where the road emerged from the crushing blanket of avalanche look like a child's toy.

Vertical Solutions Helicopters pilot Douglas Furney watched the biggest avalanche tumble down on Saturday.

The force of the snow was so great that for a moment it reversed the river.

"I saw something I bet nobody else has ever seen," he said. "The Lowe River flowed backwards."

State transportation officials say water is draining from the lake behind the giant snow pile -- the damalanche -- but the instability of the snow and the huge amount of water behind it makes conditions too dangerous for crews to start clearing debris.

TIMELINE EMERGES

Officials say it's possible that road clearing at Mile 16 could end as early as Sunday or perhaps a few days after, unless the weather or other factors intrude. Then they need to check for any damage, though engineers said they didn't expect anything serious.

Jason Sakalaskas, a Valdez-based engineer with the state Department of Transportation, said Wednesday an estimate he gave the Valdez City Council Monday night still stands: three to four days for the water to drop enough to start work, then another three or four days to clear the avalanche debris in hopes of reopening the road, barring any serious damage to the now-submerged pavement.

If you do the math, that equals as early as Sunday or as late as Tuesday.

But Sakalaskas said he doesn't want to get that specific.

"We're trying not to state any dates because it could start to rain," he said. "It is reducing ... we went from an estimate of 10 to 15 feet of water (depth) on the north side to 5 to 10. We do see a positive decrease."

The flooded area behind the snow dam measured 1,500 feet long as of Wednesday morning, a significant reduction from the 2,500-foot reading estimated on Monday, officials say. Water is gushing through an abandoned highway tunnel, Sakalaskas said. It's also flowing through the river channel under all that snow -- normally a frozen trickle this month, the Lowe is cranking at about a third of its summer volume, when boaters come to play in its whitewater.

State officials had originally said water was draining from an old railroad tunnel.

EVACUATION ADVISORY LIFTED

As engineers keep watch on water levels at Mile 16, two subdivisions below the dammed area are still under a flash flood watch, but the dropping water levels led a state hydrology expert to consider any threat to the Alpine Woods and Nordic subdivisions "to have decreased significantly," according to a Valdez city update.

Police sirens would warn residents should there be any kind of sudden water release detected; the city canceled its weekly Wednesday siren test "due to current circumstances," the update said.

The city is also closing an emergency shelter established in town for any subdivision residents who wanted to leave.

"No one used it but people did leave their homes and stay with friends and family," deputy city clerk Holly Wolgamott said.

The Alaska Marine Highway System and Ravn Alaska -- the new name for Era Alaska -- have increased ferry and air service to Valdez.

A statement from the state Transportation Department reminded drivers to watch for flaggers and heavy equipment on the highway and to "exercise extreme caution if traveling through mountain passes in this region as there is an increased possibility for more avalanches to occur."

Zaz Hollander reported from Wasilla and Michelle Theriault Boots reported from Valdez. Email: zhollander@adn.com and mtheriault@adn.com.

 

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