Renton Focused on Landslide Areas

Along Hwy 169 Following OSO Tragedy

In the wake of the Oso tragedy in Snohomish County, the City of Renton is focused on providing more careful and frequent inspections of hillsides and slopes throughout the city, including along Hwy 169. A key element of the effort will include actions private property owners and the city can do to protect citizens. Mayor Denis Law said property owners are responsible for their slopes or hillsides, if they’re on private land.

Maple Valley Slides on Hwy 169-1 Renton-Landslide

“I think the city and property owners have the responsibility to investigate situations where there are potential landslide hazards, particularly when such slides would pose a risk to safety and property,” said the City’s public works administrator Gregg Zimmerman.

The City’s public works staff has identified at least 10 spots in Renton that the City says need monitoring or upkeep, including but not limited to:

  • 1700 Lake Washington Blvd. N.
  • Renton Hill above Narco
  • a former industrial site at the bottom of Renton Hill
  • Hardie Avenue, near Fred Meyer
  • Rainier Avenue, next to the airport
  • Maplewood Glen, and
  • Along Maple Valley Highway (Hwy 169). The city intends to perform a geotechnical evaluation of the embankment along the Maple Valley Highway “to determine level of risk and potential remedial measures” to further stabilize the slopes along SR-169.

The City says these areas were included because there are potential landslide hazards, including steep slopes and places where there is a history of landslides. The proximity of businesses and residences to the areas was a factor in assessing the risk posed by the slide hazards.

Zimmerman advised the City Council that where residential developments were built on top of the hill, there has actually been an improvement – less frequent and less severe slides. “This is because the storm water runoff is now collected in a closed-pipe system and is not allowed to percolate through the hillside.”

Zimmerman indicated the City’s plan includes writing property owners, completing periodic inspections, conducting geotechnical studies to determine if remedial action is needed and adding structures to strengthen the slope.