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Investigation finds burst water pipe led to Skagway dock sinking

Pat Forgey
Alaska Marine Highway System service to Skagway was suspended after the community's floating dock sank overnight on April 23, 2014. Officials determined that a burst water line led to the dock's sinking. Alaska DOT

JUNEAU -- In hindsight, maybe it wasn't such a good idea to drill holes in the Skagway public dock's watertight compartments. Still, it did work for 36 years.

Last spring though, the dock, where Alaska state ferries and other vessels moor, mysteriously sank.

One morning, the dock -- which was supposed to be floating -- was sitting on the ocean floor. No one new why.

Borough manager Scott Hahn had been on the job about a week when Skagway lost one of its links to the rest of Alaska.

"I was just basically getting my feet wet at the time," he said.

Fortunately, Skagway is one of the few Southeast communities with a road connection to the outside world. If someone urgently needed to travel by ferry they could drive through Canada's Yukon and embark in neighboring Haines. While that journey is 17 miles by ferry, it's 350 miles by road. And tourist season was looming.

The dock itself is jointly owned by the city and the state and used by both. The Department of Transportation dispatched engineers, followed by salvage crews to Skagway.

With cruise ships on the way, the search for a cause behind the sinking wasn't the top priority.

The dock is of an unusual style, made up of 24 separate hollow, floating concrete chambers.

Fast work by the salvage company, Western Marine, got the dock back in service by the time the tourist season started and the small cruise ships were able to begin using it.

Cruise ships using the dock bring in relatively few passengers, but are an important part of the economy and sometimes stay overnight. This allows visitors to see a different Skagway than those on the huge ships, city officials said. Larger ships use a separate dock.

Now, the department says marine engineers have identified the problem.

"The cause of the Skagway Ferry Terminal dock submersion was a burst water pipe valve that was located under the deck of the dock in one of the concrete floating chambers," said Jeremy Woodrow, spokesperson for the department and ferry system.

Someone, apparently in the dock's early days, decided to run a water line to serve vessels on the dock. Instead of running the line alongside the floating chambers, it was decided to drill holes in them and run it through the chambers instead.

That appears to have worked for 36 years, until this year, Woodrow said. That's when someone failed to drain water out of the 3-inch line for the winter. Water left in the line froze, causing the pipe and a valve to burst, he said.

On April 23, the line was turned on for the first time; the next morning, the dock was found underwater.

Woodrow said water slowly flowed into the compartment unseen, filling that compartment. That then pulled the neighboring compartments down until water flowed into the top, and so on until all were under water.

Skagway Harbormaster Matt O'Boyle said he hadn't yet heard about the conclusions about the cause of the dock sinking, and declined comment.

City officials said earlier they suspected it might be a water line issue. The night the dock sank, city water usage doubled, but nobody reported a leak.

The dock is now back in service, but water is now provided by a garden hose on the dock, O'Boyle said. State ferries take on water at other ports.

Repairs cost about $400,000, with an additional $300,000 in repairs to come, Woodrow said.

That includes new electrical service and a new water line. That line will run outside the floating dock's compartments.

Contact Pat Forgey at pat@alaskadispatch.com.