After Oso, fears of local landslides arise
April 8, 2014
By Peter Clark
After the devastating Oso mudslide March 22, long-held fears arose in Issaquah.
“It’s scary,” resident Philip Cherian said about the large hill steeply rising over Southeast Black Nugget Road, blocked from the roadway, Home Depot and Fred Meyer by a wall. “We live in the area and drive by there, and you can see water seeping through.”
Rapid earth movement at that site, and at others around town, has long been a concern for the city. Public Works Engineering Director Sheldon Lynne said the city has remained vigilant over the Southeast Black Nugget Road site, performing studies on the private property.
“The wall is structurally stable,” Lynne wrote in an email. “The city retained a geotechnical engineer and structural engineer to evaluate the retaining wall below the hillside for its integrity. The report identified that the wall was constructed in 2001 and is structurally stable.”
He said the wall received permitting through King County and once the land entered Issaquah, the city added steel cross-bracings to the wall for added safety. The city continues to observe the structural soundness of the wall more than once a year or whenever it rains heavily, and financially plan for maintenance and inspection, Lynne said.
However, because the land is private, the city has limited options.
“The land above shows signs of earth movement,” Lynne said. “Since the land is on private property, however, the city has no control over it. The city has contacted the property owner and informed them of their responsibilities.”
Cherian said however secure the wall, it does not look like it.
“Perception is reality in a lot of cases,” he said. “It doesn’t look solid. It doesn’t look stable.”
Because of this perception, it has even affected how his family shops.
“My wife has decided not to shop at Fred Meyer,” he said. “It makes her nervous and after the mudslide at Oso, she said, ‘That’s it, I’m not shopping at Fred Meyer.’”
Another site of concern for the city has been Mountainside Drive Southwest on Squak Mountain, less than a mile downhill from the Forest Rim neighborhood. The city relocated a water main away from a movement area as a precaution in 2011 and continues to monitor it.
“The city retained a geotechnical engineering firm to evaluate the hillside and landslide area in 2011,” Lynne said. “The Public Works Operations has checked the area monthly, and Public Works Engineering has periodically observed it since 2011, as recently as last week, without any noticeable movement.”
City Communications Manager Autumn Monahan said Issaquah has built landslide protection into the future of the city’s development.
“Issaquah’s permitting process for new development helps minimize landslide risk,” she said. “We’ve actually limited some development in the past due to potential hazards. We are also on the lookout for warning signs of extensive earth movement.”