Daily Sitka Sentinel

City to Follow Up On Landslide Advisory

By SHANNON HAUGLAND

Sentinel Staff Writer

A day after releasing preliminary findings about the moderate risk of a slide below Gavan Hill, city staff is planning the next possible steps for the community.

“We have a responsibility to ensure public safety to the highest ability we can,” City Administrator Mark Gorman said.

“It’s important we do everything in our powers to identify the risk,” agreed Public Works Director Michael Harmon. “Nothing is ever a guarantee, but we’re doing our due diligence to identify the risk and create a safe environment.”

The preliminary findings based on a “desktop analysis” from the Seattle geotechnical consulting firm Shannon & Wilson found that populated areas of town below Gavan Hill, including Keet Gooshi Heen Elementary School, may contain landslide hazard zones. City staff received the analysis on Friday, and released the news to the public on Monday afternoon.

The preliminary findings were not a particular surprise to some at city hall who had heard from a project manager on the Keet Gooshi Heen construction project in the 1980s that some ancient landslide material was on the site where the school was built, as well as the ballfield location. Harmon stressed that’s just anecdotal information, and he looks forward to more geotechnical data. Gorman said he has heard that old landslide debris was found on the sites of houses constructed in the Gavan subdivision.

Speaking of the preliminary findings released Friday, Harmon said:

“This concerned me greatly – the potential risk of the neighborhood and the school has compelled me to look into that risk. We realize it’s not well defined and we need to do more work ... Let’s make sure we know what we’re dealing with.”

To that end, city staff has asked Shannon & Wilson for a proposal for a more detailed study of Gavan as well as the area above Sitka High School, including possible mitigation steps. It would be similar to the firm’s report on south Kramer Avenue and the study under way on the area above the Gary Paxton Industrial Park, although the Kramer study didn’t include mitigation options.

There is currently no budget for this item, but city staff says that some of the $500,000 balance from the 2016 budget could be used – with Assembly approval – to complete a detailed study that includes Sitka High. 

Gorman said he hopes to have the proposal back from Shannon & Wilson some time in the next month and to be able to make a proposal to the Assembly. The study on south Benchlands delineated the hillside into low, medium and high risk zones, and provided models of possible future slides.

Gorman said what’s missing from the studies is probability.

“We have a risk scale that goes low to high but we don’t have a probability scale that goes with it,” he said. “Is there a way to measure probability?”

The preliminary finding that KGH is in a “moderate risk” area is prompting city staff to want a more detailed analysis. The desktop study was funded by leftover funds from a past Shannon & Wilson contract to study landslide risks on Kramer.

The Assembly and Planning Commission have taken positions in favor of learning more about landslide and other disaster risks, and passed motions supporting the state going after money from the Federal Emergency Management Administration for a complete study that covers the entire town. But at the same time, the city has been going ahead in light of last year’s landslides to fund studies and start to consider mitigation options.

“If the report came back and said that KGH is high risk of landslide, I think we would kick into high gear with an aggressive plan to deal with it,” Gorman said. “We’ve got to get more information. That information may potentially trigger more action.”

The desktop analysis was completed using data from geotechnical reports dating from the school construction project and the closure of the old landfill, as well as LIDAR data from the Alaska Division of Geological & Geophysical Surveys, said Bill Laprade, senior vice president at Shannon & Wilson. He noted that more data is being compiled by NASA.

As to whether the firm would be able to assess risk probability, Laprade declined to comment.

Gorman said the city discussed what information to release and when after receiving the oral preliminary report on Friday. He informed School Superintendent Mary Wegner and decided to notify the public immediately.

“We felt it was critically important to be as transparent as possible on this,” Gorman said. “We didn’t want to be accused of withholding this information from the citizens.”
Gorman said he’s looking at setting aside about $250,000 from the unspent 2016 funds not only on more detailed studies, but also landslide-related legal fees and possible mitigation recommendations for high risk zones. The cost of the industrial park landslide risk study alone is estimated at $60,000.

“These are expensive,” the administrator said. “This could go on for years.”

The city has brought in Scott Brylinsky as an assistant planner to work on a “critical areas ordinance.” Such ordinances are in effect in Seattle and Juneau and other communities, adding extra requirements for property owners and developers building in high-risk areas. Gorman said he’s also interested in exploring options for an early warning system for landslides.