City of Edmonds has taken steps to reduce landslide risk, consultant says

Updated at 9:30 p.m. May 7 with additional detail on Council visioning next steps.

While Edmonds has its share of landslide-prone areas, a geotechnical engineer who has been monitoring the stability of Edmonds slopes told the Edmonds City Council Tuesday night that the city has implemented measures to reduce the risk for landslides and/or damage resulting from any slides that may occur.

Steve Wright talks about soil conditions that can lead to landslides.

The presentation was conducted by Steve Wright, P.E., of Landau Associates, which has been providing technical support to the City on slope stability issues for many years, and was in response to citizen concerns about landslide risks following the tragedy in Oso.

While Edmonds has several areas prone to slides, Tuesday night’s presentation focused on the North Edmonds Earth Subsidence and Landslide Hazard Area, otherwise known as ESLHA (see map).

ESLHA map

Wright noted that in general, landslides in the Puget Sound region “are fairly common.”  They are typically along waterfront bluffs, preceded by periods extended rainfall, he said.

Due to slide concerns in the North Edmonds area, the City of Edmonds did impose a building moratorium in the late 1970s. The ban was lifted in 1984, after the addition of sewer and drainage systems significantly improved slope stability by lowering groundwater levels.

According to Wright, the City of Edmonds then passed an ordinance in 1988 that outlined development requirements for the North Edmonds slide hazard are, including the signing of many “hold-harmless” agreements by developers, engineers, geotechnical scientists, and homeowners who seek to locate homes there.

Wright also assured the council that while there were some similarities between between the slide areas in North Edmonds and Oso, there were also many differences. Among them:

– Oso has a major river that cuts into the toe of slope, removing support, which Edmonds doesn’t have.

– Unlike Oso, Edmonds has no extensive logging or land-clearing activities.

– Unlike Edmonds, the Oso area did not have a drainage system installed to handle groundwater.

– Slope heights are very different between the two communities: 650 feet for Oso vs 300-400 feet for Edmonds.

– Oso soils are loose deposits while Edmonds soils are much more dense. “With density comes strength,” Wright noted.

In other action, the council:

-Approved an amendment adding the City of Arlington to an interlocal agreement between several municipalities — including Edmonds — to fund the Alliance for Housing Affordability.

– Authorized the mayor to sign two professional services agreements: One with The Blueline Group for various city-funded capital projects that are scheduled to begin construction in 2014 and 2015, and the other with KPG, P.S. for design of walkway improvements on 15th Street Southwest from Edmonds Way to 8th Avenue South.

– Discussed the Council Vision Planning for 2014, started during the Council’s retreat earlier this year. This item drew some spirited discussion among councilmembers as Council President Diane Buckshnis proposed that she identify a future work session during which the council could further discuss their top six identified items –Highway 99, affordable housing, long-term transportation funding, historical preservation in the downtown area, economic development and a year-round farmers market.

However, Councilmember Joan Bloom said she would prefer to involve Jim Reid of the Falconer Group – who has been hired to conduct workshops on council/staff communications — and use the exercise as a way to help refine the council’s approach.

Buckshnis confirmed Wednesday that the council received an email from Reid stating that he while he does facilitate areas like vision planning, that is not part of his contract. “He did say he was sorry that all of his services might have been misinterpreted to fall under any area,” she added.
she had spoken to Reid about the idea and he wasn’t interested; Bloom countered that she also had spoken to Reid and he was open to the idea.

Next step is for Buckshnis to again approach Reid and report back.

 

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4 Comments

  1. The Landau consultant made no mention of global warming and climate change which is happening right now at a ferocious pace. To only talk about historical records does not give a complete report on the changes that are right now occurring……..and it is known science that over development has created many new problems in reguards to geographical unstable environments………This is not unique to Edmonds…….We need to stop the rubber stamping of random development for short term gains……need more objectivity from outside sources

  2. AGW & ACC &the latest “Anthropogenic Climate Disruption” is one of the biggest hoaxes perpetrated on the American public in recent memory.

    • Please elaborate on your statement, and it would be great if you would also clarify for us un-informed folks the meaning of the terms AGW & ACC…? – Thank You

  3. While not every possible situation can be predicted, I am aware of some of the Edmonds requirements to lessen the problems of homes built on slopes.or near small streams when we built our house. Here are some:
    1. Requirements to replace loose soil with quarry spalls
    2. Requirements to build away from streams and plant natives for stability and ability to absorb water.
    3. Required to Install a detention system which involves having a large pipe installed on the downside of the lot into which the roof water drains to slow its absorption in heavy rains.
    4. Required to have testing on our lot for soil and water concerns before we built
    We have lived in Edmonds over 10 years and our observation is that our system does its job. After a heavy rain we don’t even see a puddle.

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