Skagway Assembly adopts engineers’ short-term fix for rockslides

Skagway rockslide damage
A rockslide on Sept. 24, 2022 wiped out the White Pass and Yukon Route Railway’s attenuator net on Skagway’s Railroad Dock. (Photo courtesy Andrew Cremata)

In an effort to reduce the hazard from rockslides that barraged Skagway’s busiest cruise ship dock during the 2022 cruise season, the municipality has contracted with a design firm to develop mitigation strategies that could allow at least partial use of the dock next season.

This year’s slides caused partial shutdowns of the dock, resulting in a loss of more than 100,000 visitors to the community. The vast majority of the town’s economy relies on cruise ship traffic.

Seattle-based Geotechnical Engineering firm Shannon and Wilson have developed two different mitigation proposals for Skagway’s large rockslide chute officials are calling the South Slide area. It’s located above the north end of the Railroad Dock and clearly visible from the waterfront. 

The two plans consist of a large-scale long-term effort costing nearly $40 million, and a smaller short-term effort that would cost a little over $3 milliion. The municipality is seeking grant funding for the long-term project but is moving ahead with the short-term project in the meantime.

Municipal officials hope that the short-term project can be done prior to next year’s cruise season. That project will include the installation of two attenuator nets. One of those, at the bottom of the slide area, was destroyed during a slide late last month, it was the large netting designed to guide falling rocks into the water below the dock. It will need to be replaced.

Another attenuator net will be installed in the mid-slope area. During Thursday’s assembly meeting, Borough Manager Brad Ryan explained why that’s necessary.

“I’d say a third of the way down or maybe just over a third of the way down, there’s a bump on the hillside, and that kicks rocks off and launches them outward,” Ryan said.

When those rocks get launched outward, they can gain speed and miss the attenuator net at the bottom of the slope causing damage to the dock below. The plan also calls for a draped mesh at the top of the slope much like what is used along stretches of the South Klondike Highway between Skagway and Carcross in Canada’s Yukon Territory. The concept is that if you can slow the speed at which the rocks fall, the impact won’t be as damaging.

Heavy scaling will also be done to the top of the slide area. That will theoretically bring down any loose rock or vegetation that’s in danger of falling now. The scaling will be done with hand tools such as pry bars and airbags. 

But Ryan doesn’t expect that the Railroad Dock will be used at full capacity upon completion of the mitigation effort.

“I think we have to be prepared that we’re going to try to limit as many people on that dock as possible,” he said.

That means most likely cruise passengers will continue to be tendered from the ships that are able to berth on the Railroad Dock south of the slide area next season.

Ryan said funding for the project will likely come from a variety of sources. Alaska Gov. Mike Dunleavy declared a disaster emergency in Skagway last month, and the state made at least $1 million available for Skagway in the wake of the declaration. There could be more funds available but those aren’t guaranteed.

Another potential source of funding could come from CPV funds which are collected by the State of Alaska as a per-passenger fee and then distributed back to communities that host cruise ships. 

“Can we cover it? I believe we can,” Ryan said. “The revenue bond has to go through and the expenses that would go to the development of the (Ore) dock would have to all go through that revenue bond, which we intend to do anyway. And then we’d have to cover it with our other municipal funds.”

A $65 million revenue bond was approved by voters on Tuesday. Those funds are supposed to be used for port development and are expected to be available early next year. The use of that money to reconfigure the Ore Dock to allow large-class cruise ships next year would allow other money, like those CPV funds, to be available to help pay for the rockslide mitigation plan instead of the emergency Ore Dock redesign project.

Shannon and Wilson expect the hand scaling to take two weeks, with building the attenuator taking eight weeks and system tests taking one week. Ryan named Oregon-based contractor Rock Supremacy as the firm that will execute the plan. The White Pass and Yukon Route Railroad will continue to share geotechnical data and remove debris from the bottom of the slide area as needed.

[Sign up for Alaska Public Media’s daily newsletter to get our top stories delivered to your inbox.]

Previous articleKodiak officials start work after survey finds problems with Alaska’s oldest building
Next articleWestern Alaska receives millions to repair roads and storm-damaged communities